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Sample records for helium-cooled divertor finger

  1. Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

    SciTech Connect

    YOUCHISON,DENNIS L.; NORTH,MART T.

    2000-11-22

    Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m{sup 2} and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm{sup 2} area. An impressive 10 kW of power was absorbed on an area of 24 cm{sup 2}. Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m{sup 2} using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented.

  2. The evolution of US helium-cooled blankets

    NASA Astrophysics Data System (ADS)

    Wong, C. P. C.; Cheng, E. T.; Schultz, K. R.

    1991-08-01

    This paper reviews and compares four helium-cooled fusion reactor blanket designs. These designs represent generic configurations of using helium to cool fusion reactor blankets that were studied over the past 20 years in the United States of America. These configurations are the pressurized module design, the pressurized tube design, the solid particulate and gas mixture design, and the nested shell design. Among these four designs, the nested shell design, which was invented for the ARIES study, is the simplest in configuration and has the least number of critical issues. Both metallic and ceramic-composite structural materials can be used for this design. It is believed that the nested shell design can be the most suitable blanket confirmation for helium-cooled fusion power and experimental reactors.

  3. Helium cooling systems for large superconducting physics detector magnets

    NASA Astrophysics Data System (ADS)

    Green, M. A.

    The large superconducting detector magnets used for high energy physics experiments are virtually all indirectly cooled. In general, these detector magnets are not cryogenically stabilized. Therefore, there are a number of choices for cooling large indirectly cooled detector magnets. These choices include; 1) forced two-phase helium cooling driven by the helium refrigerator J-T circuit, 2) forced two-phase helium cooling driven by a helium pump, and 3) a peculation gravity feed cooling system which uses liquid helium from a large storage dewar. The choices for the cooling of a large detector magnet are illustrated by applying these concepts to a 4.2 meter diameter 0.5 tesla thin superconducting solenoid for an experiment at the Relativistic Heavy Ion Collider (RHIC).

  4. Evaluation of US demo helium-cooled blanket options

    SciTech Connect

    Wong, C.P.C.; McQuillan, B.W.; Schleicher, R.W.

    1995-10-01

    A He-V-Li blanket design was developed as a candidate for the U.S. fusion demonstration power plant. This paper presents an 18 MPa helium-cooled, lithium breeder, V-alloy design that can be coupled to the Brayton cycle with a gross efficiency of 46%. The critical issue of designing to high gas pressure and the compatibility between helium impurities and V-alloy are addressed.

  5. High capacity 30 K remote helium cooling loop

    NASA Astrophysics Data System (ADS)

    Trollier, T.; Tanchon, J.; Icart, Y.; Ravex, A.

    2014-01-01

    Absolut System has built several 50 K remote helium cooling loops used as high capacity and very low vibration cooling source into large wavelength IR detectors electro-optical characterization test benches. MgB2 based superconducting electro-technical equipment's under development require also distributed high cooling power in the 20-30 K temperature range. Absolut System has designed, manufactured and tested a high capacity 30 K remote helium cooling loop. The equipment consists of a CRYOMECH AL325 type cooler, a CP830 type compressor package used as room temperature circulator and an intermediate LN2 bath cooling used between two recuperator heat exchangers (300 K-77 K and 77 K-20 K). A cooling capacity of 30 W @ 20 K or 80 W @ 30 K has been demonstrated on the application heat exchanger, with a 4-meter remote distance ensured by a specifically designed gas circulation flexible line. The design and the performance will be reported in this paper.

  6. Design of a helium-cooled molten salt fusion breeder

    SciTech Connect

    Moir, R.W.; Lee, J.D.; Fulton, F.J.; Huegel, F.; Neef, W.S. Jr.; Sherwood, A.E.; Berwald, D.H.; Whitley, R.H.; Wong, C.P.C.; DeVan, J.H.

    1985-02-01

    A new conceptual blanket design for a fusion reactor produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF + BeF/sub 2/ + TghF/sub 4/) is circulated through the blanket and on to the online processing system where /sup 233/U and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. We estimate the breeder, having 3000 MW of fusion power, produces 6400 kg of /sup 233/U per year, which is enough to provide make up for 20 GWe of LWR per year (or 14 LWR plants of 4440 MWt) or twice that many HTGRs or CANDUs. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem mirror is estimated to cost $4.9B or 2.35 times an LWR of the same power. The estimated present value cost of the /sup 2/anumber/sup 3/U produced is $40/g if utility financed or $16/g if government financed.

  7. Design of a helium-cooled molten salt fusion breeder

    NASA Astrophysics Data System (ADS)

    Moir, R. W.; Lee, J. D.; Fulton, F. J.; Huegel, F.; Neef, W. S., Jr.; Sherwood, A. E.; Berwald, D. H.; Whitley, R. H.; Wong, C. P. C.; Devan, J. H.

    1985-02-01

    A new conceptual blanket design for a fusion reactor is discussed which produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF + BeF2 + TghF4) is circulated through the blanket and on to the online processing system where (233)U and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS mirror is estimated to cost $4.9B or 2.35 time an LWR of the same power. The estimated present value cost of the (233)U produced is $40/g if utility financed or $16/g if government financed.

  8. Helium-Cooled Refractory Alloys First Wall and Blanket Evaluation

    SciTech Connect

    Wong, C.P.C.; Nygren, R.E.; Baxi, C.B.; Fogarty, P.; Ghoniem, N.; Khater, H.; McCarthy, K.; Merrill, B.; Nelson, B.; Reis, E.E.; Sharafat, S.; Schleicher, R.; Sze, D.K.; Ulrickson, M.; Willms, S.; Youssef, M.; Zinkel, S.

    1999-08-01

    Under the APEX program the He-cooled system design task is to evaluate and recommend high power density refractory alloy first wall and blanket designs and to recommend and initiate tests to address critical issues. We completed the preliminary design of a helium-cooled, W-5Re alloy, lithium breeder design and the results are reported in this paper. Many areas of the design were assessed, including material selection, helium impurity control, and mechanical, nuclear and thermal hydraulics design, and waste disposal, tritium and safety design. System study results show that at a closed cycle gas turbine (CCGT) gross thermal efficiency of 57.5%, a superconducting coil tokamak reactor, with an aspect ratio of 4, and an output power of 2 GWe, can be projected to have a cost of electricity at 54.6 mill/kWh. Critical issues were identified and we plan to continue the design on some of the critical issues during the next phase of the APEX design study.

  9. Development of a feed monitor system for a helium-cooled Michelson intererometer for the Spacelab

    NASA Technical Reports Server (NTRS)

    Essenwanger, P.

    1980-01-01

    A Michelson interferometer feed monitor system developed for Spacelab is described. The device is helium cooled and is to be used to measure far infrared radiation sources in space. Performance data and development sequence are presented.

  10. Helium-cooled molten-salt fusion breeder

    SciTech Connect

    Moir, R.W.; Lee, J.D.; Fulton, F.J.; Huegel, F.; Neef, W.S. Jr.; Sherwood, A.E.; Berwald, D.H.; Whitley, R.H.; Wong, C.P.C.; Devan, J.H.

    1984-12-01

    We present a new conceptual design for a fusion reactor blanket that is intended to produce fissile material for fission power plants. Fast fission is suppressed by using beryllium instead of uranium to multiply neutrons. Thermal fission is suppressed by minimizing the fissile inventory. The molten-salt breeding medium (LiF + BeF/sub 2/ + ThF/sub 4/) is circulated through the blanket and to the on-line processing system where /sup 233/U and tritium are continuously removed. Helium cools the blanket and the austenitic steel tubes that contain the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion by molten salt. We estimate that a breeder having 3000 MW of fusion power will produce 6500 kg of /sup 233/U per year. This amount is enough to provide makeup for 20 GWe of light-water reactors per year or twice that many high-temperature gas-cooled reactors or Canadian heavy-water reactors. Safety is enhanced because the afterheat is low and blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem mirror is estimated to cost $4.9B or 2.35 times a light-water reactor of the same power. The estimated cost of the /sup 233/U produced is $40/g for fusion plants costing 2.35 times that of a light-water reactor if utility owned or $16/g if government owned.

  11. Helium-Cooled Black Shroud for Subscale Cryogenic Testing

    NASA Technical Reports Server (NTRS)

    Tuttle, James; Jackson, Michael; DiPirro, Michael; Francis, John

    2011-01-01

    This shroud provides a deep-space simulating environment for testing scaled-down models of passively cooling systems for spaceflight optics and instruments. It is used inside a liquid-nitrogen- cooled vacuum chamber, and it is cooled by liquid helium to 5 K. It has an inside geometry of approximately 1.6 m diameter by 0.45 m tall. The inside surfaces of its top and sidewalls have a thermal absorptivity greater than 0.96. The bottom wall has a large central opening that is easily customized to allow a specific test item to extend through it. This enables testing of scale models of realistic passive cooling configurations that feature a very large temperature drop between the deepspace-facing cooled side and the Sun/Earth-facing warm side. This shroud has an innovative thermal closeout of the bottom wall, so that a test sample can have a hot (room temperature) side outside of the shroud, and a cold side inside the shroud. The combination of this closeout and the very black walls keeps radiated heat from the sample s warm end from entering the shroud, reflecting off the walls and heating the sample s cold end. The shroud includes 12 vertical rectangular sheet-copper side panels that are oriented in a circular pattern. Using tabs bent off from their edges, these side panels are bolted to each other and to a steel support ring on which they rest. The removable shroud top is a large copper sheet that rests on, and is bolted to, the support ring when the shroud is closed. The support ring stands on four fiberglass tube legs, which isolate it thermally from the vacuum chamber bottom. The insides of the cooper top and side panels are completely covered with 25- mm-thick aluminum honeycomb panels. This honeycomb is painted black before it is epoxied to the copper surfaces. A spiral-shaped copper tube, clamped at many different locations to the outside of the top copper plate, serves as part of the liquid helium cooling loop. Another copper tube, plumbed in a series to the

  12. Divertor detachment

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, Sergei

    2015-11-01

    The heat exhaust is one of the main conceptual issues of magnetic fusion reactor. In a standard operational regime the large heat flux onto divertor target reaches unacceptable level in any foreseeable reactor design. However, about two decades ago so-called ``detached divertor'' regimes were found. They are characterized by reduced power and plasma flux on divertor targets and look as a promising solution for heat exhaust in future reactors. In particular, it is envisioned that ITER will operate in a partly detached divertor regime. However, even though divertor detachment was studied extensively for two decades, still there are some issues requiring a new look. Among them is the compatibility of detached divertor regime with a good core confinement. For example, ELMy H-mode exhibits a very good core confinement, but large ELMs can ``burn through'' detached divertor and release large amounts of energy on the targets. In addition, detached divertor regimes can be subject to thermal instabilities resulting in the MARFE formation, which, potentially, can cause disruption of the discharge. Finally, often inner and outer divertors detach at different plasma conditions, which can lead to core confinement degradation. Here we discuss basic physics of divertor detachment including different mechanisms of power and momentum loss (ionization, impurity and hydrogen radiation loss, ion-neutral collisions, recombination, and their synergistic effects) and evaluate the roles of different plasma processes in the reduction of the plasma flux; detachment stability; and an impact of ELMs on detachment. We also evaluate an impact of different magnetic and divertor geometries on detachment onset, stability, in- out- asymmetry, and tolerance to the ELMs. Supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences under Award Number DE-DE-FG02-04ER54739 at UCSD.

  13. Deep Burn Develpment of Transuranic Fuel for High-Temperature Helium-Cooled Reactors - July 2010

    SciTech Connect

    Snead, Lance Lewis; Besmann, Theodore M; Collins, Emory D; Bell, Gary L

    2010-08-01

    The DB Program Quarterly Progress Report for April - June 2010, ORNL/TM/2010/140, was distributed to program participants on August 4. This report discusses the following: (1) TRU (transuranic elements) HTR (high temperature helium-cooled reactor) Fuel Modeling - (a) Thermochemical Modeling, (b) 5.3 Radiation Damage and Properties; (2) TRU HTR Fuel Qualification - (a) TRU Kernel Development, (b) Coating Development, (c) ZrC Properties and Handbook; and (3) HTR Fuel Recycle - (a) Recycle Processes, (b) Graphite Recycle, (c) Pyrochemical Reprocessing - METROX (metal recovery from oxide fuel) Process Development.

  14. Flow instabilities in non-uniformly heated helium jet arrays used for divertor PFCs

    SciTech Connect

    Youchison, Dennis L.

    2015-07-30

    In this study, due to a lack of prototypical experimental data, little is known about the off-normal behavior of recently proposed divertor jet cooling concepts. This article describes a computational fluid dynamics (CFD) study on two jet array designs to investigate their susceptibility to parallel flow instabilities induced by non-uniform heating and large increases in the helium outlet temperature. The study compared a single 25-jet helium-cooled modular divertor (HEMJ) thimble and a micro-jet array with 116 jets. Both have pure tungsten armor and a total mass flow rate of 10 g/s at a 600 °C inlet temperature. We investigated flow perturbations caused by a 30 MW/m2 off-normal heat flux applied over a 25 mm2 area in addition to the nominal 5 MW/m2 applied over a 75 mm2 portion of the face. The micro-jet array exhibited lower temperatures and a more uniform surface temperature distribution than the HEMJ thimble. We also investigated the response of a manifolded nine-finger HEMJ assembly using the nominal heat flux and a 274 mm2 heated area. For the 30 MW/m2 case, the micro-jet array absorbed 750 W in the helium with a maximum armor surface temperature of 1280 °C and a fluid/solid interface temperature of 801 °C. The HEMJ absorbed 750 W with a maximum armor surface temperature of 1411 °C and a fluid/solid interface temperature of 844 °C. For comparison, both the single HEMJ finger and the micro-jet array used 5-mm-thick tungsten armor. The ratio of maximum to average temperature and variations in the local heat transfer coefficient were lower for the micro-jet array compared to the HEMJ device. Although high heat flux testing is required to validate the results obtained in these simulations, the results provide important guidance in jet design and manifolding to increase heat removal while providing more even temperature distribution and minimizing non-uniformity in the gas flow and thermal stresses at the

  15. Flow instabilities in non-uniformly heated helium jet arrays used for divertor PFCs

    DOE PAGES

    Youchison, Dennis L.

    2015-07-30

    In this study, due to a lack of prototypical experimental data, little is known about the off-normal behavior of recently proposed divertor jet cooling concepts. This article describes a computational fluid dynamics (CFD) study on two jet array designs to investigate their susceptibility to parallel flow instabilities induced by non-uniform heating and large increases in the helium outlet temperature. The study compared a single 25-jet helium-cooled modular divertor (HEMJ) thimble and a micro-jet array with 116 jets. Both have pure tungsten armor and a total mass flow rate of 10 g/s at a 600 °C inlet temperature. We investigated flowmore » perturbations caused by a 30 MW/m2 off-normal heat flux applied over a 25 mm2 area in addition to the nominal 5 MW/m2 applied over a 75 mm2 portion of the face. The micro-jet array exhibited lower temperatures and a more uniform surface temperature distribution than the HEMJ thimble. We also investigated the response of a manifolded nine-finger HEMJ assembly using the nominal heat flux and a 274 mm2 heated area. For the 30 MW/m2 case, the micro-jet array absorbed 750 W in the helium with a maximum armor surface temperature of 1280 °C and a fluid/solid interface temperature of 801 °C. The HEMJ absorbed 750 W with a maximum armor surface temperature of 1411 °C and a fluid/solid interface temperature of 844 °C. For comparison, both the single HEMJ finger and the micro-jet array used 5-mm-thick tungsten armor. The ratio of maximum to average temperature and variations in the local heat transfer coefficient were lower for the micro-jet array compared to the HEMJ device. Although high heat flux testing is required to validate the results obtained in these simulations, the results provide important guidance in jet design and manifolding to increase heat removal while providing more even temperature distribution and minimizing non-uniformity in the gas flow and thermal stresses at the armor joint.« less

  16. The Helium Cooling System and Cold Mass Support System for theMICE Coupling Solenoid

    SciTech Connect

    Wang, L.; Wu, H.; Li, L.K.; Green, M.A.; Liu, C.S.; Li, L.Y.; Jia, L.X.; Virostek, S.P.

    2007-08-27

    The MICE cooling channel consists of alternating threeabsorber focus coil module (AFC) and two RF coupling coil module (RFCC)where the process of muon cooling and reacceleration occurs. The RFCCmodule comprises a superconducting coupling solenoid mounted around fourconventional conducting 201.25 MHz closed RF cavities and producing up to2.2T magnetic field on the centerline. The coupling coil magnetic fieldis to produce a low muon beam beta function in order to keep the beamwithin the RF cavities. The magnet is to be built using commercialniobium titanium MRI conductors and cooled by pulse tube coolers thatproduce 1.5 W of cooling capacity at 4.2 K each. A self-centering supportsystem is applied for the coupling magnet cold mass support, which isdesigned to carry a longitudinal force up to 500 kN. This report willdescribe the updated design for the MICE coupling magnet. The cold masssupport system and helium cooling system are discussed indetail.

  17. A Liquid-Helium-Cooled Absolute Reference Cold Load forLong-Wavelength Radiometric Calibration

    SciTech Connect

    Bensadoun, M.; Witebsky, C.; Smoot, George F.; De Amici,Giovanni; Kogut, A.; Levin, S.

    1990-05-01

    We describe a large (78-cm) diameter liquid-helium-cooled black-body absolute reference cold load for the calibration of microwave radiometers. The load provides an absolute calibration near the liquid helium (LHe) boiling point, accurate to better than 30 mK for wavelengths from 2.5 to 25 cm (12-1.2 GHz). The emission (from non-LHe temperature parts of the cold load) and reflection are small and well determined. Total corrections to the LHe boiling point temperature are {le} 50 mK over the operating range. This cold load has been used at several wavelengths at the South Pole and at the White Mountain Research Station. In operation, the average LHe loss rate was {le} 4.4 l/hr. Design considerations, radiometric and thermal performance and operational aspects are discussed. A comparison with other LHe-cooled reference loads including the predecessor of this cold load is given.

  18. THE VALUE OF HELIUM-COOLED REACTOR TECHNOLOGIES OF NUCLEAR WASTE

    SciTech Connect

    C. RODRIGUEZ; A. BAXTER

    2001-03-01

    Helium-cooled reactor technologies offer significant advantages in accomplishing the waste transmutation process. They are ideally suited for use with thermal, epithermal, or fast neutron energy spectra. They can provide a relatively hard thermal neutron spectrum for transmutation of fissionable materials such as Pu-239 using ceramic-coated transmutation fuel particles, a graphite moderator, and a non-fertile burnable poison. These features (1) allow deep levels of transmutation with minimal or no intermediate reprocessing, (2) enhance passive decay heat removal via heat conduction and radiation, (3) allow operation at relatively high temperatures for a highly efficient generation of electricity, and (4) discharge the transmuted waste in a form that is highly resistant to corrosion for long times. They also offer the possibility for the use of epithermal neutrons that can interact with transmutable materials more effectively because of the large atomic cross sections in this energy domain. A fast spectrum may be useful for deep burnup of certain minor actinides. For this application, helium is essentially transparent to neutrons, does not degrade neutron energies, and offers the hardest possible neutron energy environment. In this paper, we report results from recent work on materials transmutation balances, safety, value to a geological repository, and economic considerations.

  19. A robust helium-cooled shield/blanket design for ITER

    NASA Astrophysics Data System (ADS)

    Wong, C. P. C.; Bourque, R. F.; Baxi, C. B.; Colleraine, A. P.; Grunloh, H. J.; Letchenberg, T.; Leuer, J. A.; Reis, E. E.; Redler, K.; Will, R.

    1993-11-01

    General Atomics Fusion and Reactor Groups have completed a helium-cooled, conceptual shield/blanket design for ITER. The configuration selected is a pressurized tubes design embedded in radially oriented plates. This plate can be made from ferritic steel or from V-alloy. Helium leakage to the plasma chamber is eliminated by conservative, redundant design and proper quality control and inspection programs. High helium pressure at 18 MPa is used to reduce pressure drop and enhance heat transfer. This high gas pressure is believed practical when confined in small diameter tubes. Ample industrial experience exists for safe high gas pressure operations. Inboard shield design is highlighted in this study since the allowable void fraction is more limited. Lithium is used as the thermal contacting medium and for tritium breeding; its safety concerns are minimized by a modular, low inventory design that requires no circulation of the liquid metal for the purpose of heat removal. This design is robust, conservative, reliable, and meets all design goals and requirements. It can also be built with present-day technology.

  20. Forced Two-Phase Helium Cooling Scheme for the Mu2e Transport Solenoid

    SciTech Connect

    Tatkowski, G.; Cheban, S.; Dhanaraj, N.; Evbota, D.; Lopes, M.; Nicol, T.; Sanders, R.; Schmitt, R.; Voirin, E.

    2015-01-01

    The Mu2e Transport Solenoid (TS) is an S-shaped magnet formed by two separate but similar magnets, TS-u and TS-d. Each magnet is quarter-toroid shaped with a centerline radius of approximately 3 m utilizing a helium cooling loop consisting of 25 to 27 horizontal-axis rings connected in series. This cooling loop configuration has been deemed adequate for cooling via forced single phase liquid helium; however it presents major challenges to forced two-phase flow such as “garden hose” pressure drop, concerns of flow separation from tube walls, difficulty of calculation, etc. Even with these disadvantages, forced two-phase flow has certain inherent advantages which make it a more attractive option than forced single phase flow. It is for this reason that the use of forced two-phase flow was studied for the TS magnets. This paper will describe the analysis using helium-specific pressure drop correlations, conservative engineering approach, helium properties calculated and updated at over fifty points, and how the results compared with those in literature. Based on the findings, the use of forced-two phase helium is determined to be feasible for steady-state cooling of the TS solenoids

  1. Forced two-phase helium cooling scheme for the Mu2e transport solenoid

    NASA Astrophysics Data System (ADS)

    Tatkowski, G.; Cheban, S.; Dhanaraj, N.; Evbota, D.; Lopes, M.; Nicol, T.; Sanders, R.; Schmitt, R.; Voirin, E.

    2015-12-01

    The Mu2e Transport Solenoid (TS) is an S-shaped magnet formed by two separate but similar magnets, TS-u and TS-d. Each magnet is quarter-toroid shaped with a centerline radius of approximately 3 m utilizing a helium cooling loop consisting of 25 to 27 horizontal-axis rings connected in series. This cooling loop configuration has been deemed adequate for cooling via forced single phase liquid helium; however it presents major challenges to forced two-phase flow such as “garden hose” pressure drop, concerns of flow separation from tube walls, difficulty of calculation, etc. Even with these disadvantages, forced two-phase flow has certain inherent advantages which make it a more attractive option than forced single phase flow. It is for this reason that the use of forced two-phase flow was studied for the TS magnets. This paper will describe the analysis using helium-specific pressure drop correlations, conservative engineering approach, helium properties calculated and updated at over fifty points, and how the results compared with those in literature. Based on the findings, the use of forced-two phase helium is determined to be feasible for steady-state cooling of the TS solenoids.

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

    SciTech Connect

    Middleton, Bobby; Pasch, James Jay; Kruizenga, Alan Michael; Walker, Matthew

    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

  3. Divertor parameters and divertor operation in ASDEX

    NASA Astrophysics Data System (ADS)

    Fussmann, G.; Ditte, U.; Eckstein, W.; Grave, T.; Keilhacker, M.; McCormick, K.; Murmann, H.; Röhr, H.; Elshaer, M.; Steuer, K.-H.; Szymanski, Z.; Wagner, F.; Becker, G.; Bernhardi, K.; Eberhagen, A.; Gehre, O.; Gernhardt, J.; Gierke, G. V.; Glock, E.; Gruber, O.; Haas, G.; Hesse, M.; Janeschitz, G.; Karger, F.; Kissel, S.; Klüber, O.; Kornherr, M.; Lisitano, G.; Mayer, H. M.; Meisel, D.; Müller, E. R.; Poschenrieder, W.; Ryter, F.; Rapp, H.; Schneider, F.; Siller, G.; Smeulders, P.; Söldner, F.; Speth, E.; Stäbler, A.; Vollmer, O.

    1984-12-01

    Recent measurements of plasma boundary and divertor scrape-off parameters for ohmically and neutral injection heated plasmas are presented. For these data the power flow onto the divertor plates and the sputtering rates at the plates are calculated and compared with separate measurements. The impurity behaviour in front of the plates is also discussed.

  4. Deep Burn: Development of Transuranic Fuel for High-Temperature Helium-Cooled Reactors- Monthly Highlights October 2010

    SciTech Connect

    Snead, Lance Lewis; Besmann, Theodore M; Collins, Emory D; Bell, Gary L

    2010-11-01

    The DB Program monthly highlights report for September 2010, ORNL/TM-2010/252, was distributed to program participants by email on October 26. This report discusses: (1) Core and Fuel Analysis; (2) Spent Fuel Management; (3) Fuel Cycle Integration of the HTR (high temperature helium-cooled reactor); (4) TRU (transuranic elements) HTR Fuel Qualification; (5) HTR Spent Fuel Recycle - (a) TRU Kernel Development (ORNL), (b) Coating Development (ORNL), (c) Characterization Development and Support, (d) ZrC Properties and Handbook; and (6) HTR Fuel Recycle.

  5. Preliminary Design of a Helium-Cooled Ceramic Breeder Blanket for CFETR Based on the BIT Concept

    NASA Astrophysics Data System (ADS)

    Ma, Xuebin; Liu, Songlin; Li, Jia; Pu, Yong; Chen, Xiangcun

    2014-04-01

    CFETR is the “ITER-like” China fusion engineering test reactor. The design of the breeding blanket is one of the key issues in achieving the required tritium breeding radio for the self-sufficiency of tritium as a fuel. As one option, a BIT (breeder insider tube) type helium cooled ceramic breeder blanket (HCCB) was designed. This paper presents the design of the BIT—HCCB blanket configuration inside a reactor and its structure, along with neutronics, thermo-hydraulics and thermal stress analyses. Such preliminary performance analyses indicate that the design satisfies the requirements and the material allowable limits.

  6. Deep Burn: Development of Transuranic Fuel for High-Temperature Helium-Cooled Reactors- Monthly Highlights September 2010

    SciTech Connect

    Snead, Lance Lewis; Besmann, Theodore M; Collins, Emory D; Bell, Gary L

    2010-10-01

    The DB Program monthly highlights report for August 2010, ORNL/TM-2010/184, was distributed to program participants by email on September 17. This report discusses: (1) Core and Fuel Analysis - (a) Core Design Optimization in the HTR (high temperature helium-cooled reactor) Prismatic Design (Logos), (b) Core Design Optimization in the HTR Pebble Bed Design (INL), (c) Microfuel analysis for the DB HTR (INL, GA, Logos); (2) Spent Fuel Management - (a) TRISO (tri-structural isotropic) repository behavior (UNLV), (b) Repository performance of TRISO fuel (UCB); (3) Fuel Cycle Integration of the HTR (high temperature helium-cooled reactor) - Synergy with other reactor fuel cycles (GA, Logos); (4) TRU (transuranic elements) HTR Fuel Qualification - (a) Thermochemical Modeling, (b) Actinide and Fission Product Transport, (c) Radiation Damage and Properties; (5) HTR Spent Fuel Recycle - (a) TRU Kernel Development (ORNL), (b) Coating Development (ORNL), (c) Characterization Development and Support, (d) ZrC Properties and Handbook; and (6) HTR Fuel Recycle - (a) Graphite Recycle (ORNL), (b) Aqueous Reprocessing, (c) Pyrochemical Reprocessing METROX (metal recovery from oxide fuel) Process Development (ANL).

  7. Divertor efficiency in ASDEX

    NASA Astrophysics Data System (ADS)

    Engelhardt, W.; Becker, G.; Behringer, K.; Campbell, D.; Eberhagen, A.; Fussmann, G.; Gehre, O.; Gierke, G. V.; Glock, E.; Haas, G.; Huang, M.; Karger, F.; Keilhacker, M.; KlÜber, O.; Kornherr, M.; Lisitano, G.; Mayer, H.-M.; Meisel, D.; Müller, E. R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Rapp, H.; Schneider, F.; Siller, G.; Steuer, K.-H.; Venus, G.; Vernickel, H.; Wagner, F.

    1982-12-01

    The divertor efficiency in ASDEX is discussed for ohmically heated plasmas. The parameters of the boundary layer both in the torus midplane and the divertor chamber have been measured. The results are reasonably well understood in terms of parallel and perpendicular transport. A high pressure of neutral hydrogen builds up in the divertor chamber and Franck-Condon particles recycle back through the divertor throat. Due to dissociation processes the boundary plasma is effectively cooled before it reaches the neutralizer plates. The shielding property of the boundary layer against impurity influx is comparable to that of a limiter plasma. The transport of iron is numerically simulated for an iron influx produced by sputtering of charge exchange neutrals at the wall. The results are consistent with the measured iron concentration. First results from a comparison of the poloidal divertor with toroidally closed limiters (stainless steel, carbon) are given. Diverted discharges are considerably cleaner and easier to create.

  8. NSTX Tangential Divertor Camera

    SciTech Connect

    A.L. Roquemore; Ted Biewer; D. Johnson; S.J. Zweben; Nobuhiro Nishino; V.A. Soukhanovskii

    2004-07-16

    Strong magnetic field shear around the divertor x-point is numerically predicted to lead to strong spatial asymmetries in turbulence driven particle fluxes. To visualize the turbulence and associated impurity line emission near the lower x-point region, a new tangential observation port has been recently installed on NSTX. A reentrant sapphire window with a moveable in-vessel mirror images the divertor region from the center stack out to R 80 cm and views the x-point for most plasma configurations. A coherent fiber optic bundle transmits the image through a remotely selected filter to a fast camera, for example a 40500 frames/sec Photron CCD camera. A gas puffer located in the lower inboard divertor will localize the turbulence in the region near the x-point. Edge fluid and turbulent codes UEDGE and BOUT will be used to interpret impurity and deuterium emission fluctuation measurements in the divertor.

  9. Spectroscopy of divertor plasmas

    SciTech Connect

    Isler, R.C.

    1995-12-31

    The requirements for divertor spectroscopy are treated with respect to instrumentation and observations on present machines. Emphasis is placed on quantitative measurements.of impurity concentrations from the interpretation of spectral line intensities. The possible influence of non-Maxwellian electron distributions on spectral line excitation in the divertor is discussed. Finally the use of spectroscopy for determining plasma temperature, density, and flows is examined.

  10. The snowflake divertor

    DOE PAGES

    Ryutov, D. D.; Soukhanovskii, V. A.

    2015-11-17

    The snowflake magnetic configuration is characterized by the presence of two closely spaced poloidal field nulls that create a characteristic hexagonal (reminiscent of a snowflake) separatrix structure. The magnetic field properties and the plasma behaviour in the snowflake are determined by the simultaneous action of both nulls, this generating a lot of interesting physics, as well as providing a chance for improving divertor performance. One of the most interesting effects of the snowflake geometry is the heat flux sharing between multiple divertor channels. The authors summarise experimental results obtained with the snowflake configuration on several tokamaks. Wherever possible, relation tomore » the existing theoretical models is described. Divertor concepts utilizing the properties of a snowflake configuration are briefly discussed.« less

  11. The snowflake divertor

    SciTech Connect

    Ryutov, D. D.; Soukhanovskii, V. A.

    2015-11-17

    The snowflake magnetic configuration is characterized by the presence of two closely spaced poloidal field nulls that create a characteristic hexagonal (reminiscent of a snowflake) separatrix structure. The magnetic field properties and the plasma behaviour in the snowflake are determined by the simultaneous action of both nulls, this generating a lot of interesting physics, as well as providing a chance for improving divertor performance. One of the most interesting effects of the snowflake geometry is the heat flux sharing between multiple divertor channels. The authors summarise experimental results obtained with the snowflake configuration on several tokamaks. Wherever possible, relation to the existing theoretical models is described. Divertor concepts utilizing the properties of a snowflake configuration are briefly discussed.

  12. Divertor bias experiments

    NASA Astrophysics Data System (ADS)

    Staebler, G. M.

    1994-06-01

    Electrical biasing of the divertor target plates has recently been implemented on several tokamaks. The results of these experiments to date will be reviewed in this paper. The bias electrode configuration is unique in each experiment. The effects of biasing on the scrape-off layer (SOL) plasma also differ. By comparing results between machines, and using theoretical models, an understanding of the basic physics of biasing begins to emerge. Divertor biasing has been demonstrated to have a strong influence on the particle and energy transport within the SOL. The ability to externally control the SOL plasma with biasing has promising applications to future tokamak reactors.

  13. Finger pain

    MedlinePlus

    Pain - finger ... Nearly everyone has had finger pain at some time. You may have: Tenderness Burning Stiffness Numbness Tingling Coldness Swelling Change in skin color Redness Many conditions, such ...

  14. Tokamak divertor maps

    NASA Astrophysics Data System (ADS)

    Punjabi, Alkesh; Verma, Arun; Boozer, Allen

    1994-08-01

    A mapping method is developed to investigate the problem of determination and control of heat-deposition patterns on the plates of a tokamak divertor. The deposition pattern is largely determined by the magnetic field lines, which are mathematically equivalent to the trajectories of a single-degree-of-freedom time-dependent Hamiltonian system. Maps are natural tools to study the generic features of such systems. The general theory of maps is presented, and methods for incorporating various features of the magnetic field and particle motion in divertor tokamaks are given. Features of the magnetic field include the profile of the rotational transform, single- versus double-null divertor, reverse map, the effects of naturally occurring low M and N, and externally imposed high-M, high-N perturbations. Particle motion includes radial diffusion, pitch angle and energy scattering, and the electric sheath at the plate. The method is illustrated by calculating the stochastic broadening in a single- null divertor tokamak. Maps provide an efficient, economic and elegant method to study the problem of motion of plasma particles in the stochastic scrape-off layer.

  15. Initial assessment of environmental effects on SiC/SiC composites in helium-cooled nuclear systems

    SciTech Connect

    Contescu, Cristian I

    2013-09-01

    This report summarized the information available in the literature on the chemical reactivity of SiC/SiC composites and of their components in contact with the helium coolant used in HTGR, VHTR and GFR designs. In normal operation conditions, ultra-high purity helium will have chemically controlled impurities (water, oxygen, carbon dioxide, carbon monoxide, methane, hydrogen) that will create a slightly oxidizing gas environment. Little is known from direct experiments on the reactivity of third generation (nuclear grade) SiC/SiC composites in contact with low concentrations of water or oxygen in inert gas, at high temperature. However, there is ample information about the oxidation in dry and moist air of SiC/SiC composites at high temperatures. This information is reviewed first in the next chapters. The emphasis is places on the improvement in material oxidation, thermal, and mechanical properties during three stages of development of SiC fibers and at least two stages of development of the fiber/matrix interphase. The chemical stability of SiC/SiC composites in contact with oxygen or steam at temperatures that may develop in off-normal reactor conditions supports the conclusion that most advanced composites (also known as nuclear grade SiC/SiC composites) have the chemical resistance that would allow them maintain mechanical properties at temperatures up to 1200 1300 oC in the extreme conditions of an air or water ingress accident scenario. Further research is needed to assess the long-term stability of advanced SiC/SiC composites in inert gas (helium) in presence of very low concentrations (traces) of water and oxygen at the temperatures of normal operation of helium-cooled reactors. Another aspect that needs to be investigated is the effect of fast neutron irradiation on the oxidation stability of advanced SiC/SiC composites in normal operation conditions.

  16. Divertor plasma detachment

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. I.; Kukushkin, A. S.; Pshenov, A. A.

    2016-05-01

    Regime with the plasma detached from the divertor targets (detached divertor regime) is a natural continuation of the high recycling conditions to higher density and stronger impurity radiation loss. Both the theoretical considerations and experimental data show clearly that the increase of the impurity radiation loss and volumetric plasma recombination causes the rollover of the plasma flux to the target when the density increases, which is the manifestation of detachment. Plasma-neutral friction (neutral viscosity effects), although important for the sustainment of high density/pressure plasma upstream and providing the conditions for efficient recombination and power loss, is not directly involved in the reduction of the plasma flux to the targets. The stability of detachment is also discussed.

  17. The snowflake divertor

    SciTech Connect

    Ryutov, D. D.; Soukhanovskii, V. A.

    2015-11-15

    The snowflake magnetic configuration is characterized by the presence of two closely spaced poloidal field nulls that create a characteristic hexagonal (reminiscent of a snowflake) separatrix structure. The magnetic field properties and the plasma behaviour in the snowflake are determined by the simultaneous action of both nulls, this generating a lot of interesting physics, as well as providing a chance for improving divertor performance. Among potential beneficial effects of this geometry are: increased volume of a low poloidal field around the null, increased connection length, and the heat flux sharing between multiple divertor channels. The authors summarise experimental results obtained with the snowflake configuration on several tokamaks. Wherever possible, relation to the existing theoretical models is described.

  18. Characterisation and reduction of the EEG artefact caused by the helium cooling pump in the MR environment: validation in epilepsy patient data.

    PubMed

    Rothlübbers, Sven; Relvas, Vânia; Leal, Alberto; Murta, Teresa; Lemieux, Louis; Figueiredo, Patrícia

    2015-03-01

    The EEG acquired simultaneously with fMRI is distorted by a number of artefacts related to the presence of strong magnetic fields, which must be reduced in order to allow for a useful interpretation and quantification of the EEG data. For the two most prominent artefacts, associated with magnetic field gradient switching and the heart beat, reduction methods have been developed and applied successfully. However, a number of artefacts related to the MR-environment can be found to distort the EEG data acquired even without ongoing fMRI acquisition. In this paper, we investigate the most prominent of those artefacts, caused by the Helium cooling pump, and propose a method for its reduction and respective validation in data collected from epilepsy patients. Since the Helium cooling pump artefact was found to be repetitive, an average template subtraction method was developed for its reduction with appropriate adjustments for minimizing the degradation of the physiological part of the signal. The new methodology was validated in a group of 15 EEG-fMRI datasets collected from six consecutive epilepsy patients, where it successfully reduced the amplitude of the artefact spectral peaks by 95 ± 2 % while the background spectral amplitude within those peaks was reduced by only -5 ± 4 %. Although the Helium cooling pump should ideally be switched off during simultaneous EEG-fMRI acquisitions, we have shown here that in cases where this is not possible the associated artefact can be effectively reduced in post processing.

  19. Far-Infrared Photometry with an 0.4-Meter Liquid Helium Cooled Balloon-Borne Telescope. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jacobson, M. R.

    1977-01-01

    A 0.4-meter aperture, liquid helium cooled multichannel far-infrared balloon-borne telescope was constructed to survey the galactic plane. Nine new sources, above a 3-sigma confidence level of 1300 Jy, were identified. Although two-thirds of the scanned area was more than 10 degrees from the galactic plane, no sources were detected in that region; all nine fell within 10 degrees and eight of those within 4 degrees of the galactic equator. Correlations with visible, compact H lines associated with radio continuum and with sources displaying spectra steeply rising between 11 and 20 microns were noted, while stellar objects were not detected.

  20. Mallet finger - aftercare

    MedlinePlus

    Baseball finger - aftercare; Drop finger - aftercare; Avulsion fracture - mallet finger - aftercare ... away from the rest of the bone (avulsion fracture) Mallet finger most often occurs when something hits ...

  1. Transport and divertor properties of the dynamic ergodic divertor

    NASA Astrophysics Data System (ADS)

    Lehnen, M.; Abdullaev, S.; Biel, W.; de Bock, M. F. M.; Brezinsek, S.; Busch, C.; Classen, I.; Finken, K. H.; von Hellermann, M.; Jachmich, S.; Jakubowski, M.; Jaspers, R.; Koslowski, H. R.; Krämer-Flecken, A.; Kikuchi, Y.; Liang, Y.; Nicolai, A.; Pospieszczyk, A.; Van Rompuy, T.; Samm, U.; Schmitz, O.; Sergienko, G.; Unterberg, B.; Wolf, R.; Zimmermann, O.; TEXTOR Team

    2005-12-01

    The concept of the dynamic ergodic divertor (DED) is based on plasma edge ergodization by a resonant perturbation. Such a divertor concept is closely related to helical or island divertors in stellerators. The base mode of the DED perturbation field can be m/n = 12/4, 6/2 or 3/1. The 3/1 base mode with its deep penetration of the perturbation field provides the excitation of tearing modes. This topic was presented elsewhere. In this contribution we concentrate on the divertor properties of the DED. We report on the characterization of the topology, transport properties in ergodic fields, impurity transport and density limit behaviour. The 12/4 base where the perturbation is restricted to the plasma edge is suitable for divertor operation. With increasing perturbation field island chains are built up at the resonance layers. Overlapping islands lead to ergodization. The plasma is guided in the laminar region via open field lines of short connection length to the divertor target. The magnetic topology is not only controlled by the coil current but especially by the edge safety factor. For appropriate edge safety factor we observe a strong temperature drop in the plasma edge, indicating an expansion of the laminar region, which is necessary to decouple the divertor plasma from the core plasma. The modifications of the magnetic topology can be directly seen, for example, from carbon emission lines. The magnetic structure is calculated by the ATLAS code and shows good agreement with the experimental findings.

  2. A cryocondensation pump for the DIII-D Advanced Divertor Program

    SciTech Connect

    Smith, J.P.; Baxi, C.; Reis, E.; Sevier, L.

    1992-03-01

    A cryocondensation pump was designed for the baffle chamber of General Atomics DIII-D tokamak and will be installed in the fall of 1992. The purpose of the pump is to study plasma density control by pumping the divertor. The pump is toroidally continuous, approximately 10 m long and located in the lower outer corner of the vacuum chamber of the machine. It consists of a 1 m{sup 2} liquid helium-cooled surface surrounded by a liquid nitrogen-cooled shield to limit the heat load on the helium-cooled surface. The liquid nitrogen-cooled surface is surrounded by a radiation/particle shield to prevent energetic particles from impacting and releasing condensed water molecules. A thermal enhancement coating was applied to the nitrogen shell to lower the maximum temperature of the shell. The coating is non-continuous to keep the toroidal electrical resistance high. The whole pump is supported off the water-cooled vacuum vessel wall. Supports for the pump were designed to accommodate the thermal differences between the 4 K helium surface, the 77 K nitrogen shells, and the 300 K vacuum vessel supporting the pump and to provide a low heat leak structural support. Disruption loading on the pump was analyzed and a finite element structural analysis of the pump was completed. A testing program was completed to evaluate coating techniques to enhance heat transfer and emissivity of the various surfaces. Fabrication tests were performed to determine the best method of attaching the liquid nitrogen flow tubes to their shield surfaces and to determine the best alternative to fabricating the different shells of the pump. A prototype sector of the pump was built to verify fabrication and assembly techniques.

  3. Trigger finger

    MedlinePlus

    ... Redness in your cut or hand Swelling or warmth in your cut or hand Yellow or green drainage from the cut Hand pain or discomfort Fever If your trigger finger returns, call your surgeon. You may need another surgery.

  4. Status of poloidal divertor experiments

    SciTech Connect

    Mahdavi, M.A.

    1986-01-01

    The poloidal divertor was originally proposed as a means of impurity control and helium ash removal. Some variations of the concept were also proposed to achieve radiative cooling of the boundary plasma. The discovery of a regime of improved confinement in beam-heated diverted plasmas has further increased the potential value of this concept for tokamak reactors. This paper reviews the poloidal divertor experiments in ASDEX, Doublet III, and PDX and reviews the status of divertor theory and some aspects of the next-generation experiments.

  5. Finger Stiffness.

    PubMed

    Oosterhoff, Thijs C H; Nota, Sjoerd P F T; Ring, David

    2015-06-01

    Background Finger stiffness varies substantially in patients with hand and upper extremity illness and can be notably more than expected for a given pathophysiology. In prior studies, pain intensity and magnitude of disability consistently correlate with coping strategies such as catastrophic thinking and kinesiophobia, which can be characterized as overprotectiveness. In this retrospective study we address the primary research question whether patients with finger stiffness are more often overprotective when the primary pathology is outside the hand (e.g. distal radius fracture) than when it is located within the hand. Methods In an orthopaedic hand surgery department 160 patients diagnosed with more finger stiffness than expected for a given pathophysiology or time point of recovery between December 2006 and September 2012 were analyzed to compare the proportion of patients characterized as overprotective for differences by site of pathology: (1) inside the hand, (2) outside the hand, and (3) psychiatric etiology (e.g. clenched fist). Results Among 160 subjects with more finger stiffness than expected, 132 (82 %) were characterized as overprotective including 88 of 108 (81 %) with pathology in the hand, 39 of 44 (89 %) with pathology outside the hand, and 5 of 8 (63 %) with psychiatric etiology. These differences were not significant. Conclusions Overprotectiveness is common in patients with more finger stiffness than expected regardless the site and type of primary pathology. It seems worthwhile to recognize and treat maladaptive coping strategies early during recovery to limit impairment, symptoms, and disability. PMID:26078497

  6. Electric field divertor plasma pump

    DOEpatents

    Schaffer, Michael J.

    1994-01-01

    An electric field plasma pump includes a toroidal ring bias electrode (56) positioned near the divertor strike point of a poloidal divertor of a tokamak (20), or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix (40) of the poloidal divertor contacts the ring electrode (56), which then also acts as a divertor plate. A plenum (54) or other duct near the electrode (56) includes an entrance aperture open to receive electrically-driven plasma. The electrode (56) is insulated laterally with insulators (63,64), one of which (64) is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode (56) and a vacuum vessel wall (22), with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E.times.B/B.sup.2 drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable.

  7. Electric field divertor plasma pump

    DOEpatents

    Schaffer, M.J.

    1994-10-04

    An electric field plasma pump includes a toroidal ring bias electrode positioned near the divertor strike point of a poloidal divertor of a tokamak, or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix of the poloidal divertor contacts the ring electrode, which then also acts as a divertor plate. A plenum or other duct near the electrode includes an entrance aperture open to receive electrically-driven plasma. The electrode is insulated laterally with insulators, one of which is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode and a vacuum vessel wall, with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E [times] B/B[sup 2] drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable. 11 figs.

  8. Actively convected liquid metal divertor

    NASA Astrophysics Data System (ADS)

    Shimada, Michiya; Hirooka, Yoshi

    2014-12-01

    The use of actively convected liquid metals with j × B force is proposed to facilitate heat handling by the divertor, a challenging issue associated with magnetic fusion experiments such as ITER. This issue will be aggravated even more for DEMO and power reactors because the divertor heat load will be significantly higher and yet the use of copper would not be allowed as the heat sink material. Instead, reduced activation ferritic/martensitic steel alloys with heat conductivities substantially lower than that of copper, will be used as the structural materials. The present proposal is to fill the lower part of the vacuum vessel with liquid metals with relatively low melting points and low chemical activities including Ga and Sn. The divertor modules, equipped with electrodes and cooling tubes, are immersed in the liquid metal. The electrode, placed in the middle of the liquid metal, can be biased positively or negatively with respect to the module. The j × B force due to the current between the electrode and the module provides a rotating motion for the liquid metal around the electrodes. The rise in liquid temperature at the separatrix hit point can be maintained at acceptable levels from the operation point of view. As the rotation speed increases, the current in the liquid metal is expected to decrease due to the v × B electromotive force. This rotating motion in the poloidal plane will reduce the divertor heat load significantly. Another important benefit of the convected liquid metal divertor is the fast recovery from unmitigated disruptions. Also, the liquid metal divertor concept eliminates the erosion problem.

  9. Advanced divertor configurations with large flux expansion

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Bell, R. E.; Diallo, A.; Gerhardt, S.; Kaye, S.; Kolemen, E.; LeBlanc, B. P.; McLean, A.; Menard, J. E.; Paul, S. F.; Podesta, M.; Raman, R.; Ryutov, D. D.; Scotti, F.; Kaita, R.; Maingi, R.; Mueller, D. M.; Roquemore, A. L.; Reimerdes, H.; Canal, G. P.; Labit, B.; Vijvers, W.; Coda, S.; Duval, B. P.; Morgan, T.; Zielinski, J.; De Temmerman, G.; Tal, B.

    2013-07-01

    Experimental studies of the novel snowflake divertor concept (D. Ryutov, Phys. Plasmas 14 (2007) 064502) performed in the NSTX and TCV tokamaks are reviewed in this paper. The snowflake divertor enables power sharing between divertor strike points, as well as the divertor plasma-wetted area, effective connection length and divertor volumetric power loss to increase beyond those in the standard divertor, potentially reducing heat flux and plasma temperature at the target. It also enables higher magnetic shear inside the separatrix, potentially affecting pedestal MHD stability. Experimental results from NSTX and TCV confirm the predicted properties of the snowflake divertor. In the NSTX, a large spherical tokamak with a compact divertor and lithium-coated graphite plasma-facing components (PFCs), the snowflake divertor operation led to reduced core and pedestal impurity concentration, as well as re-appearance of Type I ELMs that were suppressed in standard divertor H-mode discharges. In the divertor, an otherwise inaccessible partial detachment of the outer strike point with an up to 50% increase in divertor radiation and a peak divertor heat flux reduction from 3-7 MW/m2 to 0.5-1 MW/m2 was achieved. Impulsive heat fluxes due to Type-I ELMs were significantly dissipated in the high magnetic flux expansion region. In the TCV, a medium-size tokamak with graphite PFCs, several advantageous snowflake divertor features (cf. the standard divertor) have been demonstrated: an unchanged L-H power threshold, enhanced stability of the peeling-ballooning modes in the pedestal region (and generally an extended second stability region), as well as an H-mode pedestal regime with reduced (×2-3) Type I ELM frequency and slightly increased (20-30%) normalized ELM energy, resulting in a favorable average energy loss comparison to the standard divertor. In the divertor, ELM power partitioning between snowflake divertor strike points was demonstrated. The NSTX and TCV experiments are

  10. Current convective instability in detached divertor plasma

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. I.; Smolyakov, A. I.

    2016-09-01

    The asymmetry of inner and outer divertors, which cause the inner divertor to detach first, while the outer one is still attached, results in the large temperature difference between the vicinities of inner and outer targets and the onset of large electric potential drop through detached plasma of the inner divertor. A large potential drop along with the inhomogeneity of the resistivity of detached plasma across the divertor leg drives the current convective instability in the inner divertor and subsequent fluctuations of radiation loss similar to that observed in experiments. The estimates of the frequency of plasma parameter fluctuations due to the current convective instability are in a reasonable agreement with experimental data. Once the outer divertor also detaches, the temperature difference between the vicinities of inner and outer targets disappears, and the driving force for the current convective instability, and resulting oscillations of radiation loss, vanishes. This feature is indeed observed in experiments.

  11. Advanced fuels modeling: Evaluating the steady-state performance of carbide fuel in helium-cooled reactors using FRAPCON 3.4

    NASA Astrophysics Data System (ADS)

    Hallman, Luther, Jr.

    Uranium carbide (UC) has long been considered a potential alternative to uranium dioxide (UO2) fuel, especially in the context of Gen IV gas-cooled reactors. It has shown promise because of its high uranium density, good irradiation stability, and especially high thermal conductivity. Despite its many benefits, UC is known to swell at a rate twice that of UO2. However, the swelling phenomenon is not well understood, and we are limited to a weak empirical understanding of the swelling mechanism. One suggested cladding for UC is silicon carbide (SiC), a ceramic that demonstrates a number of desirable properties. Among them are an increased corrosion resistance, high mechanical strength, and irradiation stability. However, with increased temperatures, SiC exhibits an extremely brittle nature. The brittle behavior of SiC is not fully understood and thus it is unknown how SiC would respond to the added stress of a swelling UC fuel. To better understand the interaction between these advanced materials, each has been implemented into FRAPCON, the preferred fuel performance code of the Nuclear Regulatory Commission (NRC); additionally, the material properties for a helium coolant have been incorporated. The implementation of UC within FRAPCON required the development of material models that described not only the thermophysical properties of UC, such as thermal conductivity and thermal expansion, but also models for the swelling, densification, and fission gas release associated with the fuel's irradiation behavior. This research is intended to supplement ongoing analysis of the performance and behavior of uranium carbide and silicon carbide in a helium-cooled reactor.

  12. Three-dimensional neutronics optimization of helium-cooled blanket for multi-functional experimental fusion-fission hybrid reactor (FDS-MFX)

    SciTech Connect

    Jiang, J.; Yuan, B.; Jin, M.; Wang, M.; Long, P.; Hu, L.

    2012-07-01

    Three-dimensional neutronics optimization calculations were performed to analyse the parameters of Tritium Breeding Ratio (TBR) and maximum average Power Density (PDmax) in a helium-cooled multi-functional experimental fusion-fission hybrid reactor named FDS (Fusion-Driven hybrid System)-MFX (Multi-Functional experimental) blanket. Three-stage tests will be carried out successively, in which the tritium breeding blanket, uranium-fueled blanket and spent-fuel-fueled blanket will be utilized respectively. In this contribution, the most significant and main goal of the FDS-MFX blanket is to achieve the PDmax of about 100 MW/m3 with self-sustaining tritium (TBR {>=} 1.05) based on the second-stage test with uranium-fueled blanket to check and validate the demonstrator reactor blanket relevant technologies based on the viable fusion and fission technologies. Four different enriched uranium materials were taken into account to evaluate PDmax in subcritical blanket: (i) natural uranium, (ii) 3.2% enriched uranium, (iii) 19.75% enriched uranium, and (iv) 64.4% enriched uranium carbide. These calculations and analyses were performed using a home-developed code VisualBUS and Hybrid Evaluated Nuclear Data Library (HENDL). The results showed that the performance of the blanket loaded with 64.4% enriched uranium was the most attractive and it could be promising to effectively obtain tritium self-sufficiency (TBR-1.05) and a high maximum average power density ({approx}100 MW/m{sup 3}) when the blanket was loaded with the mass of {sup 235}U about 1 ton. (authors)

  13. The lithium vapor box divertor

    NASA Astrophysics Data System (ADS)

    Goldston, R. J.; Myers, R.; Schwartz, J.

    2016-02-01

    It has long been recognized that volumetric dissipation of the plasma heat flux from a fusion power system is preferable to its localized impingement on a material surface. Volumetric dissipation mitigates both the anticipated very high heat flux and intense particle-induced damage due to sputtering. Recent projections to a tokamak demonstration power plant suggest an immense upstream parallel heat flux, of order 20 GW m-2, implying that fully detached operation may be a requirement for the success of fusion power. Building on pioneering work on the use of lithium by Nagayama et al and by Ono et al as well as earlier work on the gas box divertor by Watkins and Rebut, we present here a concept for a lithium vapor box divertor, in which lithium vapor extracts momentum and energy from a fusion-power-plant divertor plasma, using fully volumetric processes. At the high powers and pressures that are projected this requires a high density of lithium vapor, which must be isolated from the main plasma in order to avoid lithium build-up on the chamber walls or in the plasma. Isolation is achieved through a powerful multi-box differential pumping scheme available only for condensable vapors. The preliminary box-wise calculations are encouraging, but much more work is required to demonstrate the practical viability of this scheme, taking into account at least 2D plasma and vapor flows within and between the vapor boxes and out of the vapor boxes to the main plasma.

  14. Divertor scenario development for NSTX Upgrade

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; McLean, A. G.; Meier, E. T.; Rognlien, T. D.; Ryutov, D. D.; Bell, R. E.; Diallo, A.; Gerhardt, S. P.; Kaita, R.; Kolemen, E.; Leblanc, B. P.; Menard, J. E.; Podesta, M.; Scotti, F.

    2012-10-01

    In the NSTX-U tokamak, initial plans for divertor plasma-facing components (PFCs) include lithium and boron coated graphite, with a staged transition to molybdenum. Steady-state peak divertor heat fluxes are projected to reach 20-30 MW/m^2 in 2 MA, 12 MW NBI-heated discharges of up to 5 s duration, thus challenging PFC thermal limits. Based on the recent NSTX divertor experiments and modeling with edge transport code UEDGE, a favorable basis for divertor power handling in NSTX-U is developed. The snowflake divertor geometry and feedback-controlled divertor impurity seeding applied to the lower and upper divertors are presently envisioned. In the NSTX snowflake experiments with lithium-coated graphite PFCs, the peak divertor heat fluxes from Type I ELMs and between ELMs were significantly reduced due to geometry effects, increased volumetric losses and null-point convective redistribution between strike points. H-mode core confinement was maintained at H98(y,2)<=1 albeit the radiative detachment. Additional CD4 seeding demonstrated potential for a further increase of divertor radiation.

  15. Effect of Divertor Shaping on Divertor Plasma Behavior on DIII-D

    NASA Astrophysics Data System (ADS)

    Petrie, T. W.; Leonard, A. W.; Luce, T. C.; Mahdavi, M. A.; Holcomb, C. T.; Fenstermacher, M. E.; Hill, D. N.; Lasnier, C. J.; Watkins, J. G.; Moyer, R. A.; Stangeby, P. C.

    2012-10-01

    Recent experiments examined the dependence of divertor density (nTAR), temperature (TTAR), and heat flux at the outer divertor separatrix target on changes in the divertor separatrix geometry. The responses of nTAR and TTAR to changes in the parallel connection length in the scrape-off layer (SOL) (L||) are consistent with the predictions of the Two Point Model (TPM). However, nTAR and TTAR display a more complex response to changes in the radial location of the outer divertor strike point (RTAR) than expected based on the TPM. SOLPS transport analysis indicates that small differences in divertor geometry can change neutral trapping sufficient to explain differences between experiment and TPM predictions. The response of the core and divertor plasmas to changes in L|| and RTAR, under both radiating and non-radiating divertor conditions, will be shown.

  16. Moving Divertor Plates in a Tokamak

    SciTech Connect

    S.J. Zweben, H. Zhang

    2009-02-12

    Moving divertor plates could help solve some of the problems of the tokamak divertor through mechanical ingenuity rather than plasma physics. These plates would be passively heated on each pass through the tokamak and cooled and reprocessed outside the tokamak. There are many design options using varying plate shapes, orientations, motions, coatings, and compositions.

  17. Optimization of a bundle divertor for FED

    SciTech Connect

    Hively, L.M.; Rothe, K.E.; Minkoff, M.

    1982-01-01

    Optimal double-T bundle divertor configurations have been obtained for the Fusion Engineering Device (FED). On-axis ripple is minimized, while satisfying a series of engineering constraints. The ensuing non-linear optimization problem is solved via a sequence of quadratic programming subproblems, using the VMCON algorithm. The resulting divertor designs are substantially improved over previous configurations.

  18. Evaluating Stellarator Divertor Designs with EMC3

    NASA Astrophysics Data System (ADS)

    Bader, Aaron; Anderson, D. T.; Feng, Y.; Hegna, C. C.; Talmadge, J. N.

    2013-10-01

    In this paper various improvements of stellarator divertor design are explored. Next step stellarator devices require innovative divertor solutions to handle heat flux loads and impurity control. One avenue is to enhance magnetic flux expansion near strike points, somewhat akin to the X-Divertor concept in Tokamaks. The effect of judiciously placed external coils on flux deposition is calculated for configurations based on the HSX stellarator. In addition, we attempt to optimize divertor plate location to facilitate the external coil placement. Alternate areas of focus involve altering edge island size to elucidate the driving physics in the edge. The 3-D nature of stellarators complicates design and necessitates analysis of new divertor structures with appropriate simulation tools. We evaluate the various configurations with the coupled codes EMC3-EIRENE, allowing us to benchmark configurations based on target heat flux, impurity behavior, radiated power, and transitions to high recycling and detached regimes. Work supported by DOE-SC0006103.

  19. Rapidly Moving Divertor Plates In A Tokamak

    SciTech Connect

    S. Zweben

    2011-05-16

    It may be possible to replace conventional actively cooled tokamak divertor plates with a set of rapidly moving, passively cooled divertor plates on rails. These plates would absorb the plasma heat flux with their thermal inertia for ~10-30 sec, and would then be removed from the vessel for processing. When outside the tokamak, these plates could be cooled, cleaned, recoated, inspected, and then returned to the vessel in an automated loop. This scheme could provide nearoptimal divertor surfaces at all times, and avoid the need to stop machine operation for repair of damaged or eroded plates. We describe various possible divertor plate designs and access geometries, and discuss an initial design for a movable and removable divertor module for NSTX-U.

  20. Current concepts: mallet finger.

    PubMed

    Alla, Sreenivasa R; Deal, Nicole D; Dempsey, Ian J

    2014-06-01

    Loss of the extensor mechanism at the distal interphalangeal (DIP) joint leads to mallet finger also known as baseball finger or drop finger. This can be secondary to tendon substance disruption or to a bony avulsion. Soft tissue mallet finger is the result of a rupture of the extensor tendon in Zone 1, and a bony mallet finger is the result of an avulsion of the extensor tendon from the distal phalanx with a small fragment of bone attached to the avulsed tendon. Mallet finger leads to an imbalance in the distribution of the extensor force between the proximal interphalangeal (PIP) and DIP joints. If left untreated, mallet finger leads to a swan neck deformity from PIP joint hyper extension and DIP joint flexion. Most mallet finger injuries can be managed non-surgically, but occasionally surgery is recommended for either an acute or a chronic mallet finger or for salvage of failed prior treatment. PMID:24839413

  1. Current concepts: mallet finger.

    PubMed

    Alla, Sreenivasa R; Deal, Nicole D; Dempsey, Ian J

    2014-06-01

    Loss of the extensor mechanism at the distal interphalangeal (DIP) joint leads to mallet finger also known as baseball finger or drop finger. This can be secondary to tendon substance disruption or to a bony avulsion. Soft tissue mallet finger is the result of a rupture of the extensor tendon in Zone 1, and a bony mallet finger is the result of an avulsion of the extensor tendon from the distal phalanx with a small fragment of bone attached to the avulsed tendon. Mallet finger leads to an imbalance in the distribution of the extensor force between the proximal interphalangeal (PIP) and DIP joints. If left untreated, mallet finger leads to a swan neck deformity from PIP joint hyper extension and DIP joint flexion. Most mallet finger injuries can be managed non-surgically, but occasionally surgery is recommended for either an acute or a chronic mallet finger or for salvage of failed prior treatment.

  2. Scrape-off layer and divertor theory meeting: Proceedings

    NASA Astrophysics Data System (ADS)

    1994-03-01

    This report contains viewgraphs on the following topics: fluid modeling of neutrals in the SOL and divertor; instabilities of gas-fueled divertors -- theory and adaptive simulations; stability of ionization fronts of gaseous divertor plasmas; monte carlo calculation of heat transport; reduced charge model for edge impurity flows; thermally collapsed solutions for gaseous/radiative divertors; adaptive grid methods in transport simulation; advanced numerical solution algorithms applied to the multispecies edge plasma equations; two-dimensional edge plasma simulation using the multigrid method; neutral behavior and the effects of neutral-neutral and neutral-ion elastic scattering in the ITER gaseous divertor; particle throughput in the TPX divertor; marfes in tokamaks; a comparative study of the limiter and divertor edge plasmas in TEXT-U; issues of toroidal tokamak-type divertor simulators; ASDEX upgrade; the ITER divertor; the D3-D divertor program and TPX divertor; DEGAS 2 -- a transmission/escape probabilities model for neutral particle transport: comparison with DEGAS 2; a collisional radiative model of hydrogen for high recycling divertors; comparison of fluid and non- fluid neutral models in B2.5; D3-D radiative divertor simulations; 3-D fluid simulations of turbulence from conducting wall mode; turbulence and drifts in SOL plasmas; recent results for 1 1/2-D ITER gas target divertor modeling; evaluation of pumping and fueling in coupled core, SOL, and divertor chamber calculations; and ITER gas target divertors -- comparison of volume recombination and large radial transport scenarios using DEGAS.

  3. Hand and Finger Exercises

    MedlinePlus

    Hand and Finger Exercises  Place your palm flat on a table. Raise and lower your fingers one ... times for ____ seconds.  Pick up objects with your hand. Start out with larger objects. Repeat ____ times for ____ ...

  4. FINAL REPORT FOR THE DIII-D RADIATIVE DIVERTOR PROJECT

    SciTech Connect

    O'NEIL, RC; STAMBAUGH, RD

    2002-06-01

    OAK A271 FINAL REPORT FOR THE DIII-D RADIATIVE DIVERTOR PROJECT. The Radiative Divertor Project originated in 1993 when the DIII-D Five Year Plan for the period 1994--1998 was prepared. The Project Information Sheet described the objective of the project as ''to demonstrate dispersal of divertor power by a factor of then with sufficient diagnostics and modeling to extend the results to ITER and TPX''. Key divertor components identified were: (1) Carbon-carbon and graphite armor tiles; (2) The divertor structure providing a gas baffle and cooling; and (3) The divertor cryopumps to pump fuel and impurities.

  5. X-point target divertor concept and the Alcator DX high power divertor test facility

    NASA Astrophysics Data System (ADS)

    Labombard, B.; Marmar, E.; Irby, J.; Vieria, R.; Wolfe, S.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hutchinson, I.; Hubbard, A.; Hughes, J.; Lin, Y.; Lipschultz, B.; Parker, R.; Porkolab, M.; Reinke, M.; Rice, J.; Shiraiwa, S.; Terry, J.; Theiler, C.; Wallace, G.; White, A.; Whyte, D.; Wukitch, S.

    2013-10-01

    Three critical challenges must be met before a steady-state, power-producing fusion reactor can be realized: (1) safely handle extreme plasma exhaust power, (2) completely suppress material erosion at divertor targets and (3) do this while maintaining a burning plasma core. Advanced divertors such as `Super X' and `X-point target' have the potential to solve all three challenges by producing a stable, fully detached, low temperature plasma in the divertor while maintaining a hot boundary layer around a clean plasma core. The X-point target divertor may be particularly effective. It places a second X-point in the pathway of the peak parallel heat flux with the intention of forming an X-point MARFE in the divertor volume, well away from the primary X-point that defines the last closed flux surface and at larger major radius, providing detachment front stability. Divertor heat dissipation is via volumetric processes (radiation, ion-neutral collisions), virtually eliminating erosion by ion bombardment and reducing peak heat flux and neutron fluence on remote divertor target components. Alcator DX is conceived as a national facility to test these ideas. It employs the high magnetic field technology of Alcator combined with high-power ICRH to investigate advanced divertors at reactor-level parallel heat flux densities.

  6. Twisted Crab fingers revisited

    NASA Astrophysics Data System (ADS)

    Carlqvist, Per

    2015-05-01

    Narrowband images of the Crab Nebula captured by the Hubble Space Telescope have earlier shown that the nebula does not only present a network of broad, bright filaments crossing the nebula but also numerous so-called fingers mostly pointing inwards. Using archival Hubble images we have in some detail studied the morphology of a great number of such fingers. This scrutiny has revealed that practically all the fingers are made up of filaments. Most of the larger fingers show overall shapes that are similar to either of the two letters V and Y. In many of these fingers it is also possible to see internal details. Interestingly, a number of the larger, Y-shaped fingers turn out to have a stem that consists of intertwined filaments. By contrast with this, the smaller fingers usually appear only as diffuse and sometimes incomplete pegs. In none of the smaller fingers is it possible to find any plain, internal structure. The observational results obtained are compared with the properties of a previously proposed model of the fingers. The model suggests that the fingers have evolved out of magnetized filaments. The evolution should lead to fingers with overall shapes that are similar to either a V or a Y, very much in agreement with the observations. In addition to this, the model prescribes that the stems of the Y-shaped fingers should be made up of intertwined filaments. From all these points of agreement we conclude that the properties of the fingers observed lend strong support to the model.

  7. Snowflake divertor configuration studies for NSTX-Upgrade

    SciTech Connect

    Soukhanovskii, V A

    2011-11-12

    Snowflake divertor experiments in NSTX provide basis for PMI development toward NSTX-Upgrade. Snowflake configuration formation was followed by radiative detachment. Significant reduction of steady-state divertor heat flux observed in snowflake divertor. Impulsive heat loads due to Type I ELMs are partially mitigated in snowflake divertor. Magnetic control of snowflake divertor configuration is being developed. Plasma material interface development is critical for NSTX-U success. Four divertor coils should enable flexibility in boundary shaping and control in NSTX-U. Snowflake divertor experiments in NSTX provide good basis for PMI development in NSTX-Upgrade. FY 2009-2010 snowflake divertor experiments in NSTX: (1) Helped understand control of magnetic properties; (2) Core H-mode confinement unchanged; (3) Core and edge carbon concentration reduced; and (4) Divertor heat flux significantly reduced - (a) Steady-state reduction due to geometry and radiative detachment, (b) Encouraging results for transient heat flux handling, (c) Combined with impurity-seeded radiative divertor. Outlook for snowflake divertor in NSTX-Upgrade: (1) 2D fluid modeling of snowflake divertor properties scaling - (a) Edge and divertor transport, radiation, detachment threshold, (b) Compatibility with cryo-pump and lithium conditioning; (2) Magnetic control development; and (3) PFC development - PFC alignment and PFC material choice.

  8. Finger snapping during seizures.

    PubMed

    Overdijk, M J; Zijlmans, M; Gosselaar, P H; Olivier, A; Leijten, F S S; Dubeau, F

    2014-01-01

    We describe two patients who showed snapping of the right hand fingers during invasive intracranial EEG evaluation for epilepsy surgery. We correlated the EEG changes with the finger-snapping movements in both patients to determine the underlying pathophysiology of this phenomenon. At the time of finger snapping, EEG spread from the supplementary motor area towards the temporal region was seen, suggesting involvement of these sites. PMID:25667884

  9. First results from the dynamic ergodic divertor at TEXTOR

    NASA Astrophysics Data System (ADS)

    Lehnen, M.; Abdullaev, S. S.; Biel, W.; Brezinsek, S.; Finken, K. H.; Harting, D.; von Hellermann, M.; Jakubowski, M.; Jaspers, R.; Kobayashi, M.; Koslowski, H. R.; Krämer-Flecken, A.; Matsunaga, G.; Pospieszczyk, A.; Reiter, D.; van Rompuy, T.; Samm, U.; Schmitz, O.; Sergienko, G.; Unterberg, B.; Wolf, R.; Zimmermann, O.; Textor Team

    2005-03-01

    Experimental results from the dynamic ergodic divertor (DED) at TEXTOR are given, describing the complex structure of the edge plasma and the properties of the divertor as well as its influence on the plasma rotation.

  10. Fingers that change color

    MedlinePlus

    ... conditions can cause fingers or toes to change color: Buerger disease Chilblains. Painful inflammation of small blood vessels. Cryoglobulinemia Frostbite Necrotizing vasculitis Peripheral artery disease ...

  11. Impurity-induced divertor plasma oscillations

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-01

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  12. Impurity-induced divertor plasma oscillations

    DOE PAGES

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-07

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ionmore » transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. As a result, the implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.« less

  13. Role of edge turbulence in detached divertor plasmas

    NASA Astrophysics Data System (ADS)

    Gang, F. Y.; Sigmar, D. J.; Krasheninnikov, S. I.

    1996-04-01

    The role of edge turbulence in detached divertor plasmas is investigated. It is shown that the edge turbulence, through poloidal transport of parallel momentum, can produce a significant plasma pressure drop along the magnetic field lines toward the divertor plate, a feature that characterizes the detached divertor plasma regime.

  14. Designing divertor targets for uniform power load

    NASA Astrophysics Data System (ADS)

    Dekeyser, W.; Reiter, D.; Baelmans, M.

    2015-08-01

    Divertor design for next step fusion reactors heavily relies on 2D edge plasma modeling with codes as e.g. B2-EIRENE. While these codes are typically used in a design-by-analysis approach, in previous work we have shown that divertor design can alternatively be posed as a mathematical optimization problem, and solved very efficiently using adjoint methods adapted from computational aerodynamics. This approach has been applied successfully to divertor target shape design for more uniform power load. In this paper, the concept is further extended to include all contributions to the target power load, with particular focus on radiation. In a simplified test problem, we show the potential benefits of fully including the radiation load in the design cycle as compared to only assessing this load in a post-processing step.

  15. Liquid metal cooled divertor for ARIES

    SciTech Connect

    Muraviev, E.

    1995-01-01

    A liquid metal, Ga-cooled divertor design was completed for the double null ARIES-II divertor design. The design analysis indicated a surface heat flux removal capability of up to 15 MW/m{sup 2}, and its relative easy maintenance. Design issues of configuration, thermal hydraulics, thermal stresses, liquid metal loop and safety effects were evaluated. For coolant flow control, it was found that it is necessary to use some part of the blanket cooling ducts for the draining of liquid metal from the top divertor. In order to minimize the inventory of Ga, it was recommended that the liquid metal loop equipment should be located as close to the torus as possible. More detailed analysis of transient conditions especially under accident conditions was identified as an issue that will need to be addressed.

  16. Design Integration of Liquid Surface Divertors

    SciTech Connect

    Nygren, R E; Cowgill, D F; Ulrickson, M A; Nelson, B E; Fogarty, P J; Rognlien, T D; Rensink, M E; Hassanein, A; Smolentsev, S S; Kotschenreuther, M

    2003-11-13

    The US Enabling Technology Program in fusion is investigating the use of free flowing liquid surfaces facing the plasma. We have been studying the issues in integrating a liquid surface divertor into a configuration based upon an advanced tokamak, specifically the ARIES-RS configuration. The simplest form of such a divertor is to extend the flow of the liquid first wall into the divertor and thereby avoid introducing additional fluid streams. In this case, one can modify the flow above the divertor to enhance thermal mixing. For divertors with flowing liquid metals (or other electrically conductive fluids) MHD (magneto-hydrodynamics) effects are a major concern and can produce forces that redirect flow and suppress turbulence. An evaluation of Flibe (a molten salt) as a working fluid was done to assess a case in which the MHD forces could be largely neglected. Initial studies indicate that, for a tokamak with high power density, an integrated Flibe first wall and divertor does not seem workable. We have continued work with molten salts and replaced Flibe with Flinabe, a mixture of lithium and sodium fluorides, that has some potential because of its lower melting temperature. Sn and Sn-Li have also been considered, and the initial evaluations on heat removal with minimal plasma contamination show promise, although the complicated 3-D MHD flows cannot yet be fully modeled. Particle pumping in these design concepts is accomplished by conventional means (ports and pumps). However, trapping of hydrogen in these flowing liquids seems plausible and novel concepts for entrapping helium are also being studied.

  17. Rolling friction robot fingers

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1992-01-01

    A low friction, object guidance, and gripping finger device for a robotic end effector on a robotic arm is disclosed, having a pair of robotic fingers each having a finger shaft slideably located on a gripper housing attached to the end effector. Each of the robotic fingers has a roller housing attached to the finger shaft. The roller housing has a ball bearing mounted centering roller located at the center, and a pair of ball bearing mounted clamping rollers located on either side of the centering roller. The object has a recess to engage the centering roller and a number of seating ramps for engaging the clamping rollers. The centering roller acts to position and hold the object symmetrically about the centering roller with respect to the X axis and the clamping rollers act to position and hold the object with respect to the Y and Z axis.

  18. Cool, high-density regime for poloidal divertors

    SciTech Connect

    Petravic, M.; Post, D.; Heifetz, D.; Schmidt, J.

    1981-08-01

    Calculations have been performed which demonstrate the possibility of operating poloidal divertors at high densities and low temperatures. This operating regime is caused primarily by ionization of recycling neutral gas near the divertor neutralizer plate which amplifies the input particle flux thereby raising the plasma density and lowering the plasma temperature. Low temperature, high density operation of poloidal divertors would ease the design requirements for future large tokamaks such as INTOR or FED by reducing the erosion rate in the divertor and reducing the neutral density and the associated charge exchange erosion near the main plasma. This regime may have already been observed on several divertor and limiter experiments.

  19. Multiple Fingers - One Gestalt.

    PubMed

    Lezkan, Alexandra; Manuel, Steven G; Colgate, J Edward; Klatzky, Roberta L; Peshkin, Michael A; Drewing, Knut

    2016-01-01

    The Gestalt theory of perception offered principles by which distributed visual sensations are combined into a structured experience ("Gestalt"). We demonstrate conditions whereby haptic sensations at two fingertips are integrated in the perception of a single object. When virtual bumps were presented simultaneously to the right hand's thumb and index finger during lateral arm movements, participants reported perceiving a single bump. A discrimination task measured the bump's perceived location and perceptual reliability (assessed by differential thresholds) for four finger configurations, which varied in their adherence to the Gestalt principles of proximity (small versus large finger separation) and synchrony (virtual spring to link movements of the two fingers versus no spring). According to models of integration, reliability should increase with the degree to which multi-finger cues integrate into a unified percept. Differential thresholds were smaller in the virtual-spring condition (synchrony) than when fingers were unlinked. Additionally, in the condition with reduced synchrony, greater proximity led to lower differential thresholds. Thus, with greater adherence to Gestalt principles, thresholds approached values predicted for optimal integration. We conclude that the Gestalt principles of synchrony and proximity apply to haptic perception of surface properties and that these principles can interact to promote multi-finger integration.

  20. Finger and toenail onycholysis.

    PubMed

    Zaias, N; Escovar, S X; Zaiac, M N

    2015-05-01

    Onycholysis - the separation of the nail plate from the nail bed occurs in fingers and toenails. It is diagnosed by the whitish appearance of the separated nail plate from the nail bed. In fingers, the majority is caused by trauma, manicuring, occupational or self-induced behavior. The most common disease producing fingernail onycholysis is psoriasis and pustular psoriasis. Phototoxic dermatitis, due to drugs can also produce finger onycholysis. Once the separation occurs, the environmental flora sets up temporary colonization in the available space. Finger onycholysis is most common in women. Candida albicans is often recovered from the onycholytic space. Many reports, want to associate the yeast as cause and effect, but the data are lacking and the treatment of the candida does not improve finger onycholysis. A reasonable explanation for the frequent isolation of Candida and Pseudomonas in fingernail onycholysis in women, is the close proximity the fingers have to the vaginal and gastrointestinal tract. Fifty per cent of humans harbour C. albicans in the GI tract and it is frequently carried to the vagina during hygienic practices. Finger onycholysis is best treated by drying the nail 'lytic' area with a hair blower, since all colonizing biota are moisture loving and perish in a dry environment. Toenail onycholysis has a very different etiology. It is mechanical, the result of pressure on the toes from the closed shoes, while walking, because of the ubiquitous uneven flat feet producing an asymmetric gait with more pressure on the foot with the flatter sole. PMID:25512134

  1. Divertor target for magnetic containment device

    DOEpatents

    Luzzi, Jr., Theodore E.

    1982-01-01

    In a plasma containment device of a type having superconducting field coils for magnetically shaping the plasma into approximately the form of a torus, an improved divertor target for removing impurities from a "scrape off" region of the plasma comprises an array of water cooled swirl tubes onto which the scrape off flux is impinged. Impurities reflected from the divertor target are removed from the target region by a conventional vacuum getter system. The swirl tubes are oriented and spaced apart within the divertor region relative to the incident angle of the scrape off flux to cause only one side of each tube to be exposed to the flux to increase the burnout rating of the target. The divertor target plane is oriented relative to the plane of the path of the scrape off flux such that the maximum heat flux onto a swirl tube is less than the tube design flux. The containment device is used to contain the plasma of a tokamak fusion reactor and is applicable to other long pulse plasma containment systems.

  2. Divertor design for the Tokamak Physics Experiment

    SciTech Connect

    Hill, D.N.; Braams, B.; Brooks, J.N.

    1994-05-01

    In this paper we discuss the present divertor design for the planned TPX tokamak, which will explore the physics and technology of steady-state (1000s pulses) heat and particle removal in high confinement (2--4{times} L-mode), high beta ({beta}{sub N} {ge} 3) divertor plasmas sustained by non-inductive current drive. The TPX device will operate in the double-null divertor configuration, with actively cooled graphite targets forming a deep (0.5 m) slot at the outer strike point. The peak heat flux on, the highly tilted (74{degrees} from normal) re-entrant (to recycle ions back toward the separatrix) will be in the range of 4--6 MW/m{sup 2} with 18 MW of neutral beams and RF heating power. The combination of active pumping and gas puffing (deuterium plus impurities), along with higher heating power (45 MW maximum) will allow testing of radiative divertor concepts at ITER-like power densities.

  3. Theoretical design of an energy recovering divertor

    NASA Astrophysics Data System (ADS)

    Baver, D. A.

    2010-11-01

    An energy recovering divertor (ERD) is a device for converting thermal to electrical energy in the divertor channel of a tokamak. Because ERD's are a type of heat engine operating at plasma temperatures, they have the thermodynamic potential for extremely high efficiencies. An ERD offers several important benefits to a tokamak fusion reactor. First, any energy recovered by the ERD is subtracted from divertor heat load, thus circumventing materials limitations. Second, energy recovered by the ERD is available for auxiliary heating, thus allowing the reactor to break even at a lower Lawson parameter. Third, an ERD can be used to power auxiliary current drive, thus reducing dependence on bootstrap current. We will present a design for an ERD based on amplification of Alfven waves in a manner analogous to a free-electron laser. While its projected efficiency falls short of the thermodynamic potential for this class of device, it nonetheless demonstrates the theoretical viability of direct power conversion in a tokamak divertor. We will also present potential approaches towards higher efficiency devices of this type. Work supported by the U.S. DOE under grant DE-FG02-97ER54392.

  4. The tungsten divertor experiment at ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Neu, R.; Asmussen, K.; Krieger, K.; Thoma, A.; Bosch, H.-S.; Deschka, S.; Dux, R.; Engelhardt, W.; García-Rosales, C.; Gruber, O.; Herrmann, A.; Kallenbach, A.; Kaufmann, M.; Mertens, V.; Ryter, F.; Rohde, V.; Roth, J.; Sokoll, M.; Stäbler, A.; Suttrop, W.; Weinlich, M.; Zohm, H.; Alexander, M.; Becker, G.; Behler, K.; Behringer, K.; Behrisch, R.; Bergmann, A.; Bessenrodt-Weberpals, M.; Brambilla, M.; Brinkschulte, H.; Büchl, K.; Carlson, A.; Chodura, R.; Coster, D.; Cupido, L.; de Blank, H. J.; de Peña Hempel, S.; Drube, R.; Fahrbach, H.-U.; Feist, J.-H.; Feneberg, W.; Fiedler, S.; Franzen, P.; Fuchs, J. C.; Fußmann, G.; Gafert, J.; Gehre, O.; Gernhardt, J.; Haas, G.; Herppich, G.; Herrmann, W.; Hirsch, S.; Hoek, M.; Hoenen, F.; Hofmeister, F.; Hohenöcker, H.; Jacobi, D.; Junker, W.; Kardaun, O.; Kass, T.; Kollotzek, H.; Köppendörfer, W.; Kurzan, B.; Lackner, K.; Lang, P. T.; Lang, R. S.; Laux, M.; Lengyel, L. L.; Leuterer, F.; Manso, M. E.; Maraschek, M.; Mast, K.-F.; McCarthy, P.; Meisel, D.; Merkel, R.; Müller, H. W.; Münich, M.; Murmann, H.; Napiontek, B.; Neu, G.; Neuhauser, J.; Niethammer, M.; Noterdaeme, J.-M.; Pasch, E.; Pautasso, G.; Peeters, A. G.; Pereverzev, G.; Pitcher, C. S.; Poschenrieder, W.; Raupp, G.; Reinmüller, K.; Riedl, R.; Röhr, H.; Salzmann, H.; Sandmann, W.; Schilling, H.-B.; Schlögl, D.; Schneider, H.; Schneider, R.; Schneider, W.; Schramm, G.; Schweinzer, J.; Scott, B. D.; Seidel, U.; Serra, F.; Speth, E.; Silva, A.; Steuer, K.-H.; Stober, J.; Streibl, B.; Treutterer, W.; Troppmann, M.; Tsois, N.; Ulrich, M.; Varela, P.; Verbeek, H.; Verplancke, Ph; Vollmer, O.; Wedler, H.; Wenzel, U.; Wesner, F.; Wolf, R.; Wunderlich, R.; Zasche, D.; Zehetbauer, T.; Zehrfeld, H.-P.

    1996-12-01

    Tungsten-coated tiles, manufactured by plasma spray on graphite, were mounted in the divertor of the ASDEX Upgrade tokamak and cover almost 90% of the surface facing the plasma in the strike zone. Over 600 plasma discharges have been performed to date, around 300 of which were auxiliary heated with heating powers up to 10 MW. The production of tungsten in the divertor was monitored by a W I line at 400.8 nm. In the plasma centre an array of spectral lines at 5 nm emitted by ionization states around W XXX was measured. From the intensity of these lines the W content was derived. Under normal discharge conditions W-concentrations around 0741-3335/38/12A/013/img12 or even lower were found. The influence on the main plasma parameters was found to be negligible. The maximum concentrations observed decrease with increasing heating power. In several low power discharges accumulation of tungsten occurred and the temperature profile was flattened. The concentrations of the intrinsic impurities carbon and oxygen were comparable to the discharges with the graphite divertor. Furthermore, the density and the 0741-3335/38/12A/013/img13 limits remained unchanged and no negative influence on the energy confinement or on the H-mode threshold was found. Discharges with neon radiative cooling showed the same behaviour as in the graphite divertor case.

  5. Tendon Driven Finger Actuation System

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); Permenter, Frank Noble (Inventor); Mehling, Joshua S. (Inventor)

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  6. Flute mode fluctuations in the divertor mirror cell

    SciTech Connect

    Katanuma, I.; Yagi, K.; Nakashima, Y.; Ichimura, M.; Imai, T.

    2010-03-15

    The computer code by reduced magnetohydrodynamic equations were made which can simulate the flute interchange modes (similar to the Rayleigh-Taylor instability) and the instability associated with the presence of nonuniform plasma flows (similar to the Kelvin-Helmholtz instability). This code is applied to a model divertor and the GAMMA10 [M. Inutake et al., Phys. Rev. Lett. 55, 939 (1985)] with divertor in order to investigate the flute modes in these divertor cells. The linear growth rate of the flute instability determined by the nonlocal linear analysis agrees with that in the linear phase of the simulations. There is a stable nonlinear steady state in both divertor cells, but the nonlinear steady state is different between the model divertor and the GAMMA10 with divertor.

  7. Modeling detachment physics in the NSTX snowflake divertor

    NASA Astrophysics Data System (ADS)

    Meier, E. T.; Soukhanovskii, V. A.; Bell, R. E.; Diallo, A.; Kaita, R.; LeBlanc, B. P.; McLean, A. G.; Podestà, M.; Rognlien, T. D.; Scotti, F.

    2015-08-01

    The snowflake divertor is a proposed technique for coping with the tokamak power exhaust problem in next-step experiments and eventually reactors, where extreme power fluxes to material surfaces represent a leading technological and physics challenge. In lithium-conditioned National Spherical Torus Experiment (NSTX) discharges, application of the snowflake divertor typically induced partial outer divertor detachment and severalfold heat flux reduction. UEDGE is used to analyze and compare conventional and snowflake divertor configurations in NSTX. Matching experimental upstream profiles and divertor measurements in the snowflake requires target recycling of 0.97 vs. 0.91 in the conventional case, implying partial saturation of the lithium-based pumping mechanism. Density scans are performed to analyze the mechanisms that facilitate detachment in the snowflake, revealing that increased divertor volume provides most of the parallel heat flux reduction. Also, neutral gas power loss is magnified by the increased wetted area in the snowflake, and plays a key role in generating volumetric recombination.

  8. NSTX Plasma Response to Lithium Coated Divertor

    SciTech Connect

    H.W. Kugel, M.G. Bell, J.P. Allain, R.E. Bell, S. Ding, S.P. Gerhardt, M.A. Jaworski, R. Kaita, J. Kallman, S.M. Kaye, B.P. LeBlanc, R. Maingi, R. Majeski, R. Maqueda, D.K. Mansfield, D. Mueller, R. Nygren, S.F. Paul, R. Raman, A.L. Roquemore, S.A. Sabbagh, H. Schneider, C.H. Skinner, V.A. Soukhanovskii, C.N. Taylor, J.R. Timberlak, W.R. Wampler, L.E. Zakharov, S.J. Zweben, and the NSTX Research Team

    2011-01-21

    NSTX experiments have explored lithium evaporated on a graphite divertor and other plasma facing components in both L- and H- mode confinement regimes heated by high-power neutral beams. Improvements in plasma performance have followed these lithium depositions, including a reduction and eventual elimination of the HeGDC time between discharges, reduced edge neutral density, reduced plasma density, particularly in the edge and the SOL, increased pedestal electron and ion temperature, improved energy confinement and the suppression of ELMs in the H-mode. However, with improvements in confinement and suppression of ELMs, there was a significant secular increase in the effective ion charge Zeff and the radiated power in H-mode plasmas as a result of increases in the carbon and medium-Z metallic impurities. Lithium itself remained at a very low level in the plasma core, <0.1%. Initial results are reported from operation with a Liquid Lithium Divertor (LLD) recently installed.

  9. Electron beam facility for divertor target experiments

    SciTech Connect

    Anisimov, A.; Gagen-Torn, V.; Giniyatulin, R.N.

    1994-12-31

    To test different concepts of divertor targets and bumpers an electron beam facility was assembled in Efremov Institute. It consists of a vacuum chamber (3m{sup 3}), vacuum pump, electron beam gun, manipulator to place and remove the samples, water loop and liquid metal loop. The following diagnostics of mock-ups is stipulated: (1) temperature distribution on the mock-up working surface (scanning pyrometer and infra-red imager); (2) temperature distribution over mocked-up thickness in 3 typical cross-sections (thermo-couples); (3) cracking dynamics during thermal cycling (acoustic-emission method), (4) defects in the mock-up before and after tests (ultra-sonic diagnostics, electron and optical microscopes). Carbon-based and beryllium mock-ups are made for experimental feasibility study of water and liquid-metal-cooled divertor/bumper concepts.

  10. Performance of the INTOR poloidal divertor

    SciTech Connect

    Post, D.E.; Petravic, M.; Schmidt, J.A.; Heifetz, D.

    1981-10-01

    The next generation of large tokamak experiments is expected to have large particle and heat outfluxes (approx. 10/sup 23/ particles/sec and 80 MW). These outfluxes must be controlled to provide adequate pumping of the helium ash and to minimize the sputtering erosion of the vacuum vessel walls, limiters, and neutralizer plates. A poloidal divertor design to solve these problems for INTOR has been done using a two-dimensional code which models the plasma as a fluid and solves equations for the flow of particles, momentum and energy, and calculates the neutral gas transport with Monte-Carlo techniques. These calculations show that there is a regime of operation where the density in the divertor is high and the temperature is low, thus easing the heat load and erosion problems. The neutral pressure at the plate is high, resulting in high gas throughputs, with modest pumping speeds.

  11. Divertor and scoop limiter experiments on PDX

    SciTech Connect

    McGuire, K.; Beiersdorfer, P.; Bell, M.; Bol, K.; Boyd, D.; Buchenauer, D.; Budny, R.; Cavallo, A.; Couture, P.; Crowley, T.

    1985-01-01

    Routine operation in the enhanced energy confinement (or H-mode) regime during neutral beam injection was achieved by modifying the PDX divertor hardware to inhibit the influx of neutral gas from the divertor region to the main plasma chamber. A particle scoop limiter has been studied as a mechanical means of controlling particles at the plasma edge, and neutral beam heated discharges with this limiter show similar confinement times (normalized to tau/sub E//I/sub p/) to average H-mode plasmas. Two new instabilities are observed near the plasma edge in PDX during H-mode operation. The first, a quasicoherent fluctuation, occurred in bursts at well-defined frequencies (..delta omega../..omega.. less than or equal to 0.1) in the range 50 to 180 kHz, and had no obvious effects on confinement. The second instability, the edge relaxation phenomena (ERP), did cause deterioration in the global confinement time. The ERP's are characterized by sharp spikes in the divertor plasma density, H/sub ..cap alpha../ emission, and on the x-ray signals they appear as sawtoothlike relaxations at the plasma edge with an inversion radius near the separatrix. Attempts to obtain high ..beta../sub T/ in the H-mode discharges were hampered by a deterioration in the H-mode confinement and major disruptions which limited the achievable ..beta../sub T/. A study of the stability of both the limiter L-mode and divertor H-mode discharges close to the theoretical ..beta.. boundary, showed that the major disruptions observed there are sometimes caused by a fast growing m/n = 1/1 mode with no observable external precursor oscillations.

  12. Neutral recirculation—the key to control of divertor operation

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. S.; Pacher, H. D.

    2016-12-01

    Interaction of the plasma with neutral gas in the divertor affects virtually all aspects of divertor functionality (power loading of the targets, pumping and fuelling, sustaining the operational conditions of the core plasma). In the course of ITER design development, this interaction has been the subject of intense modelling analysis, supported by experiments on various tokamaks. Neutral gas puffing is found to be the most effective means of divertor control. The results of those studies are summarized and assessed in the paper.

  13. Three-dimensional modeling of plasma edge transport and divertor fluxes during application of resonant magnetic perturbations on ITER

    NASA Astrophysics Data System (ADS)

    Schmitz, O.; Becoulet, M.; Cahyna, P.; Evans, T. E.; Feng, Y.; Frerichs, H.; Loarte, A.; Pitts, R. A.; Reiser, D.; Fenstermacher, M. E.; Harting, D.; Kirschner, A.; Kukushkin, A.; Lunt, T.; Saibene, G.; Reiter, D.; Samm, U.; Wiesen, S.

    2016-06-01

    Results from three-dimensional modeling of plasma edge transport and plasma-wall interactions during application of resonant magnetic perturbation (RMP) fields for control of edge-localized modes in the ITER standard 15 MA Q  =  10 H-mode are presented. The full 3D plasma fluid and kinetic neutral transport code EMC3-EIRENE is used for the modeling. Four characteristic perturbed magnetic topologies are considered and discussed with reference to the axisymmetric case without RMP fields. Two perturbation field amplitudes at full and half of the ITER ELM control coil current capability using the vacuum approximation are compared to a case including a strongly screening plasma response. In addition, a vacuum field case at high q 95  =  4.2 featuring increased magnetic shear has been modeled. Formation of a three-dimensional plasma boundary is seen for all four perturbed magnetic topologies. The resonant field amplitudes and the effective radial magnetic field at the separatrix define the shape and extension of the 3D plasma boundary. Opening of the magnetic field lines from inside the separatrix establishes scrape-off layer-like channels of direct parallel particle and heat flux towards the divertor yielding a reduction of the main plasma thermal and particle confinement. This impact on confinement is most accentuated at full RMP current and is strongly reduced when screened RMP fields are considered, as well as for the reduced coil current cases. The divertor fluxes are redirected into a three-dimensional pattern of helical magnetic footprints on the divertor target tiles. At maximum perturbation strength, these fingers stretch out as far as 60 cm across the divertor targets, yielding heat flux spreading and the reduction of peak heat fluxes by 30%. However, at the same time substantial and highly localized heat fluxes reach divertor areas well outside of the axisymmetric heat flux decay profile. Reduced RMP amplitudes due to screening or reduced RMP

  14. Constrained ripple optimization of Tokamak bundle divertors

    SciTech Connect

    Hively, L.M.; Rome, J.A.; Lynch, V.E.; Lyon, J.F.; Fowler, R.H.; Peng, Y-K.M.; Dory, R.A.

    1983-02-01

    Magnetic field ripple from a tokamak bundle divertor is localized to a small toroidal sector and must be treated differently from the usual (distributed) toroidal field (TF) coil ripple. Generally, in a tokamak with an unoptimized divertor design, all of the banana-trapped fast ions are quickly lost due to banana drift diffusion or to trapping between the 1/R variation in absolute value vector B ..xi.. B and local field maxima due to the divertor. A computer code has been written to optimize automatically on-axis ripple subject to these constraints, while varying up to nine design parameters. Optimum configurations have low on-axis ripple (<0.2%) so that, now, most banana-trapped fast ions are confined. Only those ions with banana tips near the outside region (absolute value theta < or equal to 45/sup 0/) are lost. However, because finite-sized TF coils have not been used in this study, the flux bundle is not expanded.

  15. ADX - Advanced Divertor and RF Tokamak Experiment

    NASA Astrophysics Data System (ADS)

    Greenwald, Martin; Labombard, Brian; Bonoli, Paul; Irby, Jim; Terry, Jim; Wallace, Greg; Vieira, Rui; Whyte, Dennis; Wolfe, Steve; Wukitch, Steve; Marmar, Earl

    2015-11-01

    The Advanced Divertor and RF Tokamak Experiment (ADX) is a design concept for a compact high-field tokamak that would address boundary plasma and plasma-material interaction physics challenges whose solution is critical for the viability of magnetic fusion energy. This device would have two crucial missions. First, it would serve as a Divertor Test Tokamak, developing divertor geometries, materials and operational scenarios that could meet the stringent requirements imposed in a fusion power plant. By operating at high field, ADX would address this problem at a level of power loading and other plasma conditions that are essentially identical to those expected in a future reactor. Secondly, ADX would investigate the physics and engineering of high-field-side launch of RF waves for current drive and heating. Efficient current drive is an essential element for achieving steady-state in a practical, power producing fusion device and high-field launch offers the prospect of higher efficiency, better control of the current profile and survivability of the launching structures. ADX would carry out this research in integrated scenarios that simultaneously demonstrate the required boundary regimes consistent with efficient current drive and core performance.

  16. Divertor Heat Flux Mitigation in the National Spherical Torus Experiment

    SciTech Connect

    Soukhanovskii, V A; Maingi, R; Gates, D A; Menard, J E; Paul, S F; Raman, R; Roquemore, A L; Bell, M G; Bell, R E; Boedo, J A; Bush, C E; Kaita, R; Kugel, H W; LeBlanc, B P; Mueller, D

    2008-08-04

    Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly-shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6 MW m{sup -2} to 0.5-2 MW m{sup -2} in small-ELM 0.8-1.0 MA, 4-6 MW neutral beam injection-heated H-mode discharges. A self-consistent picture of outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

  17. Two-chamber model for divertors with plasma recycling

    SciTech Connect

    Langer, W.D.; Singer, C.E.

    1985-06-01

    To model particle and heat-loss terms at the edge of a tokamak with a divertor or pumped limiter, a simple two-chamber formuluation of the scrapeoff has been constructed by integrating the fluid equations, including sources, along open field lines. The model is then solved for a wide range of density and temperature conditions in the scrapeoff, using geometrical parameters typical of the poloidal divertor in the poloidal divertor experiment (PDX). The solutions characterize four divertor operating conditions for beam-heated plasmas: plugged, unplugged, blowthrough, and blowback.

  18. Osseointegrated finger prostheses.

    PubMed

    Doppen, P; Solomons, M; Kritzinger, S

    2009-02-01

    Amputation of a digit can lead to functional and psychological problems and patients can benefit from digital prostheses. Unfortunately, standard prostheses are often unstable, particularly when fitted over short amputation stumps. Prosthesis fixation by osseointegration is widely used in oral and extraoral applications and may help avoid the problem of instability. This paper reports the results of four patients with five finger amputations who were treated with osseointegrated implants to attach finger prostheses. One implant failed to osseointegrate and the procedure was abandoned. Three patients were successfully treated to completion of three finger prostheses and are extremely satisfied with their outcomes, both cosmetically and functionally, with osseoperception reported by all three patients. PMID:19091736

  19. Multi-fingered robotic hand

    NASA Technical Reports Server (NTRS)

    Ruoff, Carl F. (Inventor); Salisbury, Kenneth, Jr. (Inventor)

    1990-01-01

    A robotic hand is presented having a plurality of fingers, each having a plurality of joints pivotally connected one to the other. Actuators are connected at one end to an actuating and control mechanism mounted remotely from the hand and at the other end to the joints of the fingers for manipulating the fingers and passing externally of the robot manipulating arm in between the hand and the actuating and control mechanism. The fingers include pulleys to route the actuators within the fingers. Cable tension sensing structure mounted on a portion of the hand are disclosed, as is covering of the tip of each finger with a resilient and pliable friction enhancing surface.

  20. Viscous fingers on fractals

    NASA Astrophysics Data System (ADS)

    Meir, Yigal; Aharony, Amnon

    1989-05-01

    We investigate the problem of flow in porous media near the percolation threshold by studying the generelized model of Viscous Fingering (VF) on fractal structures. We obtain analytic expressions for the fractal dimensions of the resulting structures, which are in excellent agreement with existing experimental results, and exact relations for the exponent Dt, which describes the scaling of the time it takes the fluid to cross the sample, with the sample size, in terms of geometrical exponents for various experimental situations. Lastly, we discuss the relation between the continuous viscous fingers model and stochastic processes such as dielectric breakdown model (DBM) and diffusion limited aggregation (DLA).

  1. Three-Fingered Robot Hand

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F.; Salisbury, J. K.

    1984-01-01

    Mechanical joints and tendons resemble human hand. Robot hand has three "human-like" fingers. "Thumb" at top. Rounded tips of fingers covered with resilient material provides high friction for griping. Hand potential as prosthesis for humans.

  2. A time dependent 2D divertor code with TVD scheme for complex divertor configurations

    NASA Astrophysics Data System (ADS)

    Shimizu, K.; Takizuka, T.; Hirayama, T.

    1999-11-01

    In order to study the transport of heat and particles in the SOL and divertor plasmas, a two-dimensional divertor code, SOLDOR has been developed. The model used in this code is identical to the B2-code. Fluid equations are discretized in space under a non orthogonal mesh to treat accurately the W shape divertor configuration of JT-60U. The total variation diminishing scheme (TVD), which is a most familiar one in computational fluid dynamics, is applied for convective terms. The equations obtained by a finite volume method (FVM) are discretized in time with a full implicit scheme and are solved time-dependently using the Newton-Raphson method. The discretized equations are solved efficiently using approximate factorization method (AF). Test calculations in the slab geometry successfully reproduced the B2 results (B.J. Braams, NET report 1987) . We are going to apply this code to JT-60U divertor plasma and investigate the flow reversal and impurity transport.

  3. RELAP5 MODEL OF THE DIVERTOR PRIMARY HEAT TRANSFER SYSTEM

    SciTech Connect

    Popov, Emilian L; Yoder Jr, Graydon L; Kim, Seokho H

    2010-08-01

    This report describes the RELAP5 model that has been developed for the divertor primary heat transfer system (PHTS). The model is intended to be used to examine the transient performance of the divertor PHTS and evaluate control schemes necessary to maintain parameters within acceptable limits during transients. Some preliminary results are presented to show the maturity of the model and examine general divertor PHTS transient behavior. The model can be used as a starting point for developing transient modeling capability, including control system modeling, safety evaluations, etc., and is not intended to represent the final divertor PHTS design. Preliminary calculations using the models indicate that during normal pulsed operation, present pressurizer controls may not be sufficient to keep system pressures within their desired range. Additional divertor PHTS and control system design efforts may be required to ensure system pressure fluctuation during normal operation remains within specified limits.

  4. OEDGE Modeling of Divertor Fueling at DIII-D

    NASA Astrophysics Data System (ADS)

    Bray, B. D.; Leonard, A. W.; Elder, J. D.; Stangeby, P. C.

    2015-11-01

    Onion-skin-modeling (OSM) is used to assess the affect of divertor closure on pedestal fueling sources. The OSM includes information from a wide range of diagnostic measurements at DIII-D to constrain the model background plasma for better simulation of neutrals and impurity ions and spectroscopy to compare to the results of the simulation. DIII-D has open lower divertor and closed upper divertor configurations which can be run with similar discharges. Progress toward modeling the pedestal fueling in low density plasmas for these cases will be presented as well as initial comparisons of recent lower single null discharges with the outer leg on the divertor shelf (fully open) and divertor floor (partially open). Work supported by the US DOE under DE-FC02-04ER54698 and DE-AC52-07NA27344.

  5. High heat flux experiments of saddle type divertor module

    NASA Astrophysics Data System (ADS)

    Suzuki, Satoshi; Akiba, Masato; Araki, Masanori; Satoh, Kazuyoshi; Yokoyama, Kenji; Dairaku, Masayuki

    1994-09-01

    JAERI has been extensively developing plasma facing components for next tokomak devices. The authors have developed a saddle type divertor module which consists of saddle-shaped armor tiles brazed on metal heat sink. This paper presents the experimental and analytical results of thermal cycling experiments of the saddle type divertor module. The divertor module has unidirectional CFC armor tiles brazed on OFHC copper heat sink. A twisted tape was inserted in the cooling tube to enhance the heat transfer. In the experiments, thermal response of the divertor module was monitored by an infrared camera and thermocouples. The maximum incident heat flux was 24.5 MW/m 2 for a duration of 30 s. No degradation of thermal response was observed during the experiment. As a result, the saddle type divertor module successfully endured at an incident heat flux of over 20 MW/m 2 under steady state conditions for 1000 cycles.

  6. Comparison of ELM heat loads in snowflake and standard divertors

    SciTech Connect

    Rognlien, T D; Cohen, R H; Ryutov, D D; Umansky, M V

    2012-05-08

    An analysis is given of the impact of the tokamak divertor magnetic structure on the temporal and spatial divertor heat flux from edge localized modes (ELMs). Two configurations are studied: the standard divertor where the poloidal magnetic field (B{sub p}) varies linearly with distance (r) from the magnetic null and the snowflake where B{sub p} varies quadratrically with r. Both one and two-dimensional models are used to analyze the effect of the longer magnetic field length between the midplane and the divertor plate for the snowflake that causes a temporal dilation of the ELM divertor heat flux. A second effect discussed is the appearance of a broad region near the null point where the poloidal plasma beta can substantially exceed unity, especially for the snowflake configuration during the ELM; such a condition is likely to drive additional radial ELM transport.

  7. The energy balance of divertor discharges in the PDX tokamak

    NASA Astrophysics Data System (ADS)

    Bell, M. G.; Fonck, R. J.; Grek, B.; Jaehnig, K. P.; Kaita, R.; Kaye, S. M.; McBride, T.; Mueller, D.; Owens, D. K.; Schmidt, G. L.

    1984-05-01

    The energy balance of divertor discharges in the PDX tokamak has been studied as a function of the divertor geometry, heating method, and discharge parameters. In the original open divertor geometry, energy flow to the neutralizers accounted for 50-60% of the input energy, while radiation from the main plasma accounted for 20-40%, depending on the density and the heating source. For single-null discharges in the modified closed divertor geometry, the main plasma radiation remains at a similar level, but the neutralizer deposition decreases to < 20% and radiation from the divertor scrape-off must be included to achieve energy accountability. The energy deposition width on the neutralizers is found to vary with plasma conditions in the closed geometry.

  8. Alternative divertor target concepts for next step fusion devices

    NASA Astrophysics Data System (ADS)

    Mazul, I. V.

    2016-12-01

    The operational conditions of a divertor target in the next steps of fusion devices are more severe in comparison with ITER. The current divertor designs and technologies have a limited application concerning these conditions, and so new design concepts/technologies are required. The main reasons which practically prevent the use of the traditional motionless solid divertor target are analyzed. We describe several alternative divertor target concepts in this paper. The comparative analysis of these concepts (including the advantages and the drawbacks) is made and the prospects for their practical implementation are prioritized. The concept of the swept divertor target with a liquid metal interlayer between the moving armour and motionless heat-sink is presented in more detail. The critical issues of this design are listed and outlined, and the possible experiments are presented.

  9. Divertor for use in fusion reactors

    DOEpatents

    Christensen, Uffe R.

    1979-01-01

    A poloidal divertor for a toroidal plasma column ring having a set of poloidal coils co-axial with the plasma ring for providing a space for a thick shielding blanket close to the plasma along the entire length of the plasma ring cross section and all the way around the axis of rotation of the plasma ring. The poloidal coils of this invention also provide a stagnation point on the inside of the toroidal plasma column ring, gently curving field lines for vertical stability, an initial plasma current, and the shaping of the field lines of a separatrix up and around the shielding blanket.

  10. Magnetic configuration flexibility of snowflake divertor for HL-2M [Analysis of snowflake divertor configurations for HL-2M

    SciTech Connect

    Zheng, G. Y.; Xu, X. Q.; Ryutov, D. D.; Pan, Y. D.; Xia, T. Y.

    2014-07-09

    HL-2M (Li, 2013 [1]) is a tokamak device that is under construction. Based on the magnetic coils design of HL-2M, four kinds of divertor configurations are calculated by CORSICA code (Pearlstein et al., 2001 [2]) with the same main plasma parameters, which are standard divertor, exact snowflake divertor, snowflake-plus divertor and snowflake-minus divertor configurations. The potential properties of these divertors are analyzed and presented in this paper: low poloidal field area around X-point, connection length from outside mid-plane to the primary X-point, target plate design and magnetic field shear. The results show that the snowflake configurations not only can reduce the heat load at divertor target plates, but also may improve the magneto-hydrodynamic stability by stronger magnetic shear at the edge. Furthermore, a new divertor configuration, named “tripod divertor”, is designed by adjusting the positions of the two X-points according to plasma parameters and magnetic coils current of HL-2M.

  11. Simulation study of power load with impurity seeding in advanced divertor "short super-X divertor" for a tokamak reactor

    NASA Astrophysics Data System (ADS)

    Asakura, N.; Hoshino, K.; Shimizu, K.; Shinya, K.; Utoh, H.; Tokunaga, S.; Tobita, K.; Ohno, N.

    2015-08-01

    A short super-X divertor (SXD) is proposed as an option for the Demo divertor, where the field line length from the divertor null to the outer target was largely increased compared to a similar-size conventional divertor. Physics and engineering design studies for a 3 GW-level fusion power Demo reactor (SlimCS) (Tobita et al., 2009) have recently progressed. Minimal number of the divertor coils were installed inside the toroidal field coil, i.e. interlink-winding. Arrangement of the poloidal field coils and their currents were determined, taking into account of the engineering design such as vacuum vessel and the neutron shield structures, and the divertor maintenance scenario. Divertor plasma simulation showed that significant radiation region is produced between the super-X null and the target. Radiation loss in the divertor was increased, producing fully detached plasmas efficiently. Advantages of the short SXD were demonstrated, but the total peak heat load was a marginal level (10 MW m-2) for the engineering design.

  12. Magnetic configuration flexibility of snowflake divertor for HL-2M [Analysis of snowflake divertor configurations for HL-2M

    DOE PAGES

    Zheng, G. Y.; Xu, X. Q.; Ryutov, D. D.; Pan, Y. D.; Xia, T. Y.

    2014-07-09

    HL-2M (Li, 2013 [1]) is a tokamak device that is under construction. Based on the magnetic coils design of HL-2M, four kinds of divertor configurations are calculated by CORSICA code (Pearlstein et al., 2001 [2]) with the same main plasma parameters, which are standard divertor, exact snowflake divertor, snowflake-plus divertor and snowflake-minus divertor configurations. The potential properties of these divertors are analyzed and presented in this paper: low poloidal field area around X-point, connection length from outside mid-plane to the primary X-point, target plate design and magnetic field shear. The results show that the snowflake configurations not only can reducemore » the heat load at divertor target plates, but also may improve the magneto-hydrodynamic stability by stronger magnetic shear at the edge. Furthermore, a new divertor configuration, named “tripod divertor”, is designed by adjusting the positions of the two X-points according to plasma parameters and magnetic coils current of HL-2M.« less

  13. Safe Finger Tourniquet--Ideas.

    PubMed

    Wei, Lin-Gwei; Chen, Chieh-Feng; Hwang, Chun-Yuan; Chang, Chiung-Wen; Chiu, Wen-Kuan; Li, Chun-Chang; Wang, Hsian-Jenn

    2016-03-01

    Tourniquets are often needed for optimized phalangeal surgeries. However, few surgeons forget to remove them and caused ischemic injuries. We have a modified method to create a safe finger tourniquet for short duration finger surgeries, which can avoid such tragedy. It is done by donning a glove, cutting the tip of the glove over the finger of interest, and rolling the glove finger to the base. From 2010 to 2013, approximately 54 patients underwent digital surgical procedures with our safe finger tourniquet. Because the glove cannot be forgotten to be removed, the tourniquet must be released and removed. This is a simple and efficient way to apply a safe finger tourniquet by using hand rubber glove for a short-term bloodless finger surgery and can achieve an excellent surgical result.

  14. Modeling of extinguishing ELMs in detached divertor plasmas

    NASA Astrophysics Data System (ADS)

    Pigarov, A.; Krasheninnikov, S.; Hollmann, E.; Rognlien, T.

    2015-11-01

    Detached plasmas, the primary operational regime for divertors in next-step fusion devices, should be compatible with both good H-mode confinement and relatively small ELMs providing tolerable heat power loads on divertor targets. Here, dynamics of boundary plasma, impurities and material walls over a sequence of many type-I ELM events under detached divertor plasma conditions is studied with UEGDE-MB-W, the newest version of 2D edge plasma transport code, which incorporates Macro-Blob (MB) approach to simulate non-diffusive filamentary transport and various ``Wall'' (W) models for time-dependent hydrogen wall inventory and recycling. We present the results of multi-parametric analysis on the impact of the size and frequency of ELMs on the divertor plasma parameters where we vary the MB characteristics under different pedestals and divertor configurations. We discuss the conditions, under which small but frequent type-I ELMs (typical for high-power H-mode discharges on current tokamaks with hard deuterium gas puff) are not ``burning through'' the formed detached divertor plasma. In this case, the inner and outer divertors are filled by sub-eV, recombining, highly-impure plasma. Variations of impurity plasma content, radiation pattern, and deuterium wall inventory over the ELM cycle are analyzed. UEDGE-MB-W modeling results are compared to available experimental data.

  15. A super-cusp divertor configuration for tokamaks

    DOE PAGES

    Ryutov, D. D.

    2015-08-26

    Our study demonstrates a remarkable flexibility of advanced divertor configurations created with the remote poloidal field coils. The emphasis here is on the configurations with three poloidal field nulls in the divertor area. We are seeking the structures where all three nulls lie on the same separatrix, thereby creating two zones of a very strong flux expansion, as envisaged in the concept of Takase’s cusp divertor. It turns out that the set of remote coils can produce a cusp divertor, with additional advantages of: (i) a large stand-off distance between the divertor and the coils and (ii) a thorough controlmore » that these coils exert over the fine features of the configuration. In reference to these additional favourable properties acquired by the cusp divertor, the resulting configuration could be called ‘a super-cusp’. General geometrical features of the three-null configurations produced by remote coils are described. Furthermore, issues on the way to practical applications include the need for a more sophisticated control system and possible constraints related to excessively high currents in the divertor coils.« less

  16. A super-cusp divertor configuration for tokamaks

    SciTech Connect

    Ryutov, D. D.

    2015-08-26

    Our study demonstrates a remarkable flexibility of advanced divertor configurations created with the remote poloidal field coils. The emphasis here is on the configurations with three poloidal field nulls in the divertor area. We are seeking the structures where all three nulls lie on the same separatrix, thereby creating two zones of a very strong flux expansion, as envisaged in the concept of Takase’s cusp divertor. It turns out that the set of remote coils can produce a cusp divertor, with additional advantages of: (i) a large stand-off distance between the divertor and the coils and (ii) a thorough control that these coils exert over the fine features of the configuration. In reference to these additional favourable properties acquired by the cusp divertor, the resulting configuration could be called ‘a super-cusp’. General geometrical features of the three-null configurations produced by remote coils are described. Furthermore, issues on the way to practical applications include the need for a more sophisticated control system and possible constraints related to excessively high currents in the divertor coils.

  17. Single active finger IPMC microgripper

    NASA Astrophysics Data System (ADS)

    Ford, Stefan; Macias, Gary; Lumia, Ron

    2015-02-01

    This paper presents a new design for a single active finger ionic polymer metal composite (IPMC) microgripper. This design has one stationary finger and one actuating finger. The gripper is tested in comparison with a two fingered gripper (2FG) on its ability to perform pick and place operations. The grippers each use IPMC strips in three widths: 1.25 mm, 2.5 mm and 5.0 mm. The single fingered gripper shows success rates of 86.2%, 89.2%, and 75% respectively versus 78.5%, 93.9% and 75% for a 2FG. The single fingered gripper performance is nearly equivalent to that of a 2FG. Even though a single finger produces half the force, its ability to carry objects is as good as or better than a 2FG. In addition, the stationary finger is considerably stiffer than an active IPMC finger, which helps in positional accuracy. Using half the IPMC, the single fingered gripper is the economical choice.

  18. Current and Potential Distribution in a Divertor with Torioidally-Asymmetric Biasing of the Divertor Plate

    SciTech Connect

    Cohen, R H; Ryutov, D D; Counsell, G F; Helander, P

    2006-06-06

    Toroidally-asymmetric biasing of the divertor plate may increase convective cross-field transport in SOL and thereby reduce the divertor heat load. Experiments performed with the MAST spherical tokamak generally agree with a simple theory of non-axisymmetric biasing. However, some of the experimental results have not yet received a theoretical explanation. In particular, existing theory seems to overestimate the asymmetry between the positive and the negative biasing. Also lacking a theoretical explanation is experimentally observed increase of the average floating potential in the main SOL in the presence of biasing. In this paper we attempt to solve these problems by accounting for the closing of the currents (driven by the biasing) in a strong-shear region near the X-point. We come up with the picture which, at least qualitatively, agrees with these experimental results.

  19. Disruption characteristics in PDX with limiter and divertor discharges

    SciTech Connect

    Couture, P.; McGuire, K.

    1986-09-01

    A comparison has been made between the characteristics of disruptions with limiter and divertor configurations in PDX. A large data base on disruptions has been collected over four years of machine operation, and a total of 15,000 discharges are contained in the data file. It was found that divertor discharges have less disruptions during ramp up and flattop of the plasma current. However, for divertor discharges a large number of fast, low current disruptions take place during the current ramp down. These disruptions are probably caused by the deformation of the plasma shape.

  20. Simulations of NSTX with a Liquid Lithium Divertor Module

    SciTech Connect

    Stotler, D. P.; Maingi, R.; Zakharov, L. E.; Kugel, H. W.; Pigarov, A. Yu.; Rognlien, T. D.; Soukhanovskii, V. A.

    2010-02-18

    A strategy to develop self-consistent simulations of the behavior of lithium in the Liquid Lithium Divertor (LLD) module to be installed in NSTX is described. In this initial stage of the plan, the UEDGE edge plasma transport code is used to simulate an existing NSTX shot, with UEDGE's transport coefficients set using midplane and divertor diagnostic data. The LLD is incorporated into the simulations as a reduction in the recycling coefficient over the outer divertor. Heat transfer calculations performed using the resulting heat flux profiles provide preliminary estimates on operating limits for the LLD as well as input data for subsequent steps in the LLD modeling effort.

  1. Simulations of NSTX with a Liquid Lithium Divertor Module

    SciTech Connect

    D. P. Stotler, R. Maingi, H.W. Kugel, A. Yu. Pigarov, T.D. Rognlien, V.A. Soukhanovskii

    2008-07-08

    The UEDGE edge plasma transport code is used to model the effect of the reduced recycling provided by the Liquid Lithium Divertor (LLD) module that will be installed in NSTX. UEDGE's transport coefficients are calibrated against an existing NSTX shot using midplane and divertor diagnostic data. The LLD is then incorporated into the simulations as a reduction in the recycling coefficient over the outer divertor. Heat transfer calculations performed using the resulting heat flux profiles indicate that lithium evaporation will be negligible for pulse lengths < 2 s at low (~ 2 MW) input power. At high input power (~ 7 MW), the pulse length may have to be restricted.

  2. Two-chamber model for divertors with plasma recycling

    SciTech Connect

    Langer, W.D.; Singer, C.E.

    1984-11-01

    To model particle and heat loss terms at the edge of a tokamak with a divertor or pumped limiter, a simple two-chamber formulation of the scrapeoff has been constructed by integrating the fluid equations, including sources, along open field lines. The model is then solved for a wide range of density and temperature conditions in the scrapeoff, using geometrical parameters typical of the PDX poloidal divertor. The solutions characterize four divertor operating conditions for beam-heated plasmas: plugged, unplugged, blowthrough, and blowback.

  3. Modeling impurities and tilted plates in the ITER divertor

    SciTech Connect

    Rensink, M.E.; Rognlien, T.D.

    1996-07-29

    The UEDGE 2-D edge transport code is used to model the effect of impurities and tilted divertor plates for the ITER SOL/divertor region. The impurities are modeled as individual charge states using either the FMOMBAL 21-moment description or parallel force balance. Both helium and neon impurities are used together with a majority hydrogenic species. A fluid description of the neutrals is used that includes parallel inertia and neutral-neutral collisions. Effects of geometry are analyzed by using the nonorthogonal mesh capability of UEDGE to obtain solutions with the divertor plate tilted at various angles.

  4. Sheath over a finely structured divertor plate

    SciTech Connect

    Cohen, R. H., LLNL

    1998-05-15

    The surface of a divertor plate typically has fine structure. Depending on the material - and the duration of exposure to the plasma, the characteristic size of the surface imperfections may vary over a broad range. In this paper, we consider the case where these structures have scale h that is much smaller than the ion gyroradius {rho}{sub i} but greater than the electron gyroradius {rho}{sub e}. The magnetic field intersects the divertor plate at a shallow angle {alpha}<divertor region of a medium-size tokamak (plasma density n{approximately}4x10{sup 13} cm{sup -3}, plasma temperature T{approximately}50 eV, the magnetic field strength B{approximately} 2T), one has: {rho}{sub i} {approximately}500 {micro}m (hydrogen), {rho}{sub e}{approximately}10 {micro}m. We, therefore, are going to analyze the scales of imperfections in the range 10 {micro}m

  5. Finger Forces in Clarinet Playing

    PubMed Central

    Hofmann, Alex; Goebl, Werner

    2016-01-01

    Clarinettists close and open multiple tone holes to alter the pitch of the tones. Their fingering technique must be fast, precise, and coordinated with the tongue articulation. In this empirical study, finger force profiles and tongue techniques of clarinet students (N = 17) and professional clarinettists (N = 6) were investigated under controlled performance conditions. First, in an expressive-performance task, eight selected excerpts from the first Weber Concerto were performed. These excerpts were chosen to fit in a 2 × 2 × 2 design (register: low–high; tempo: slow–fast, dynamics: soft–loud). There was an additional condition controlled by the experimenter, which determined the expression levels (low–high) of the performers. Second, a technical-exercise task, an isochronous 23-tone melody was designed that required different effectors to produce the sequence (finger-only, tongue-only, combined tongue-finger actions). The melody was performed in three tempo conditions (slow, medium, fast) in a synchronization-continuation paradigm. Participants played on a sensor-equipped Viennese clarinet, which tracked finger forces and reed oscillations simultaneously. From the data, average finger force (Fmean) and peak force (Fmax) were calculated. The overall finger forces were low (Fmean = 1.17 N, Fmax = 3.05 N) compared to those on other musical instruments (e.g., guitar). Participants applied the largest finger forces during the high expression level performance conditions (Fmean = 1.21 N). For the technical exercise task, timing and articulation information were extracted from the reed signal. Here, the timing precision of the fingers deteriorated the timing precision of the tongue for combined tongue-finger actions, especially for faster tempi. Although individual finger force profiles were overlapping, the group of professional players applied less finger force overall (Fmean = 0.54 N). Such sensor instruments provide useful insights into player

  6. Robotic Finger Assembly

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Bridgwater, Lyndon (Inventor); Diftler, Myron A. (Inventor); Linn, Douglas Martin (Inventor); Platt, Robert J., Jr. (Inventor); Hargrave, Brian (Inventor); Askew, Scott R. (Inventor); Valvo, Michael C. (Inventor)

    2014-01-01

    A robotic hand includes a finger with first, second, and third phalanges. A first joint rotatably connects the first phalange to a base structure. A second joint rotatably connects the first phalange to the second phalange. A third joint rotatably connects the third phalange to the second phalange. The second joint and the third joint are kinematically linked such that the position of the third phalange with respect to the second phalange is determined by the position of the second phalange with respect to the first phalange.

  7. Robotic Finger Assembly

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Bridgwater, Lyndon (Inventor); Diftler, Myron A. (Inventor); Linn, Douglas M. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Askew, Scott R. (Inventor); Valvo, Michael C. (Inventor)

    2013-01-01

    A robotic hand includes a finger with first, second, and third phalanges. A first joint rotatably connects the first phalange to a base structure. A second joint rotatably connects the first phalange to the second phalange. A third joint rotatably connects the third phalange to the second phalange. The second joint and the third joint are kinematically linked such that the position of the third phalange with respect to the second phalange is determined by the position of the second phalange with respect to the first phalange.

  8. Divertor IR thermography on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Terry, J. L.; LaBombard, B.; Brunner, D.; Payne, J.; Wurden, G. A.

    2010-10-01

    Alcator C-Mod is a particularly challenging environment for thermography. It presents issues that will similarly face ITER, including low-emissivity metal targets, low-Z surface films, and closed divertor geometry. In order to make measurements of the incident divertor heat flux using IR thermography, the C-Mod divertor has been modified and instrumented. A 6° toroidal sector has been given a 2° toroidal ramp in order to eliminate magnetic field-line shadowing by imperfectly aligned divertor tiles. This sector is viewed from above by a toroidally displaced IR camera and is instrumented with thermocouples and calorimeters. The camera provides time histories of surface temperatures that are used to compute incident heat-flux profiles. The camera sensitivity is calibrated in situ using the embedded thermocouples, thus correcting for changes and nonuniformities in surface emissivity due to surface coatings.

  9. Divertor transport study in the large helical device

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Feng, Y.; Masuzaki, S.; Shoji, M.; Miyazawa, J.; Morisaki, T.; Ohyabu, N.; Ashikawa, N.; Komori, A.; Motojima, O.; Igitkhanov, Y.; Sardei, F.; Reiter, D.; LHD Experimental Group

    2007-06-01

    The edge transport properties in LHD have been investigated in order to clarify divertor/SOL functions of heliotron type device. The momentum loss, mainly through friction of counter-flows induced by ergodic field lines, breaks the pressure conservation along flux tubes. This prevents high recycling regime even at high density operation, n bar ∼ 7 ×1019m-3 . The momentum loss is found to be larger than in W7-AS. This is because of the higher ratio of perpendicular and parallel transport scale length, ∼10-4, in the ergodic layer, which enhances the friction between counter-flows more than in the island divertor. In the heliotron configuration, a large temperature drop from LCFS to divertor by an order of magnitude is easily realized due to the long connection length in the ergodic layer. This is certainly a favourable feature for future reactors in terms of reduction of damage on the divertor plate.

  10. Status of National Spherical Torus Experiment Liquid Lithium Divertor

    NASA Astrophysics Data System (ADS)

    Kugel, H. W.; Viola, M.; Ellis, R.; Bell, M.; Gerhardt, S.; Kaita, R.; Kallman, J.; Majeski, R.; Mansfield, D.; Roquemore, A. L.; Schneider, H.; Timberlake, J.; Zakharov, L.; Nygren, R. E.; Allain, J. P.; Maingi, R.; Soukhanovskii, V.

    2009-11-01

    Recent NSTX high power divertor experiments have shown significant and recurring benefits of solid lithium coatings on plasma facing components to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. The next step in this work is the 2009 installation of a Liquid Lithium Divertor (LLD). The 20 cm wide LLD located on the lower outer divertor, consists of four, 80 degree sections; each section is separated by a row of graphite diagnostic tiles. The temperature controlled LLD structure consists of a 0.01cm layer of vacuum flame-sprayed, 50 percent porous molybdenum, on top of 0.02 cm, 316-SS brazed to a 1.9 cm Cu base. The physics design of the LLD encompasses the desired plasma requirements, the experimental capabilities and conditions, power handling, radial location, pumping capability, operating temperature, lithium filling, MHD forces, and diagnostics for control and characterization.

  11. Transport studies in the snowflake divertor in TCV

    NASA Astrophysics Data System (ADS)

    Reimerdes, H.; Canal, G. P.; Coda, S.; Duval, B. P.; Labit, B.; Piras, F.; Vijvers, W.; de Temmerman, G.; Zielinski, J.; Tal, B.; Medvedev, S. Y.; Rognlien, T. D.; Ryutov, D. D.; Umansky, M. V.

    2011-10-01

    The transport of heat and particles in a tokamak plasma with a snowflake divertor has been studied in recent TCV experiments. Estimates of the power flux onto the divertor plates are obtained from measurements with multiple infrared cameras and Langmuir probes. The studies include L- and ELMy H-mode plasmas and confirm some of the advantageous properties of the snowflake configuration, such as the distribution of the exhaust power on more strike points than the two that characterize conventional divertor configurations. Modifications of the divertor configuration from single null towards a perfect snowflake (second-order null) show that already near-snowflake configurations lead to an appreciable power flux across the region of weak poloidal magnetic field. This work is partly funded by the Fonds National Suisse de la Recherche Scientifique. LLNL work was performed under DOE contract DE-AC52-07NA27344.

  12. Diagnostics for the DIII-D radiative divertor

    SciTech Connect

    Nilson, D.G.; Brooks, N.H.; Smith, J.P.; Snider, R.T.

    1995-10-01

    This paper reviews the design of new diagnostics and the modifications to existing diagnostics needed to carry out radiative divertor experiments in DIII-D following installation in late 1996 of a set of baffle structures that will restrict the backflow to the core plasma of neutral deuterium atoms and impurity gases. The divertor slots formed by the new baffle structures will inhibit the easy view of the divertor legs and target plates that the open divertor geometry in DIII-D currently affords. We review a basic set of diagnostics that are needed to demonstrate the reduction of divertor heat loading and radiative dissipation of energy within the divertor. This will include IR cameras, bolometry, foil bolometers, and Langmuir probes. Within the limits of available funding, we will implement a supplemental set of instruments which provide a more detailed understanding of the underlying physical processes. Many existing diagnostics require only re-aiming to provide proper coverage of the initial 23 cm long divertor plasma configuration (X- point to floor distance). Other diagnostics need extensive reconfiguration using in-vessel fiber-optic bundles or high power laser mirrors. The new divertor baffle panels provide a protective shelf for diagnostic hardware mounted underneath them, but the water cooling channels in the panels limit the permissible size of through holes and, thereby, restrict the available views of under-the- baffle diagnostics. The successful resolution of the design and implementation of these diagnostic modifications is dependent on a strong coordination between GA and its many diagnostic collaborators.

  13. Development of a radiative divertor for DIII-D

    SciTech Connect

    Allen, S.L.; Brooks, N.H.; Campbell, R.B.

    1994-07-01

    We have used experiments and modeling to develop a new radiative divertor configuration for DIII-D. Gas puffing experiments with the existing open divertor have shown the creation of a localized ({approximately}10 cm diameter) radiation zone which results in substantial reduction (3--10) in the divertor heat flux while {delta}{sub E} remains {approximately}2 times ITER-89P scaling. However, ne increases with D{sub 2} puffing, and Z{sub eff} increases with neon puffing. Divertor structures are required to minimize the effects on the core plasma. The UEDGE fluid code, benchmarked with DIII-D data, and the DEGAS neutrals transport code are used to estimate the effectiveness of divertor configurations; slots reduce the core ionization more than baffles. The overall divertor shape is set by confinement studies which indicate that high triangularity ({delta} {approximately}0.8) is important for high {tau}{sub E} VH-modes. Results from engineering feasibility studies, including diagnostic access, will be presented.

  14. Turbulent Simulations of Divertor Detachment Based On BOUT + + Framework

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Xu, Xueqiao; Xia, Tianyang; Ye, Minyou

    2015-11-01

    China Fusion Engineering Testing Reactor is under conceptual design, acting as a bridge between ITER and DEMO. The detached divertor operation offers great promise for a reduction of heat flux onto divertor target plates for acceptable erosion. Therefore, a density scan is performed via an increase of D2 gas puffing rates in the range of 0 . 0 ~ 5 . 0 ×1023s-1 by using the B2-Eirene/SOLPS 5.0 code package to study the heat flux control and impurity screening property. As the density increases, it shows a gradually change of the divertor operation status, from low-recycling regime to high-recycling regime and finally to detachment. Significant radiation loss inside the confined plasma in the divertor region during detachment leads to strong parallel density and temperature gradients. Based on the SOLPS simulations, BOUT + + simulations will be presented to investigate the stability and turbulent transport under divertor plasma detachment, particularly the strong parallel gradient driven instabilities and enhanced plasma turbulence to spread heat flux over larger surface areas. The correlation between outer mid-plane and divertor turbulence and the related transport will be analyzed. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-675075.

  15. Finger Mathematics for EMR Children.

    ERIC Educational Resources Information Center

    Ogletree, Earl J.; Chavez, Maria

    An approach to teaching mildly retarded children math skills using finger calculation is discussed. Drills progress from using one to two hands and doing multiplication and division. The appropriateness of finger calculation with children in the sensory motor and preoperational stages of development is noted, and the approach's ability to enhance…

  16. Gert Finger Becomes Emeritus Physicist

    NASA Astrophysics Data System (ADS)

    de Zeeuw, T.; Lucuix, C.; Péron, M.

    2016-03-01

    Gert Finger has retired after almost 33 years service and he has been made the first Emeritus Physicist at ESO. An appreciation of some of his many achievements in the development of infrared instrumentation and detector controllers is given. A retirement party for Gert Finger was held in February 2016.

  17. Optimal three finger grasps

    NASA Technical Reports Server (NTRS)

    Demmel, J.; Lafferriere, G.

    1989-01-01

    Consideration is given to the problem of optimal force distribution among three point fingers holding a planar object. A scheme that reduces the nonlinear optimization problem to an easily solved generalized eigenvalue problem is proposed. This scheme generalizes and simplifies results of Ji and Roth (1988). The generalizations include all possible geometric arrangements and extensions to three dimensions and to the case of variable coefficients of friction. For the two-dimensional case with constant coefficients of friction, it is proved that, except for some special cases, the optimal grasping forces (in the sense of minimizing the dependence on friction) are those for which the angles with the corresponding normals are all equal (in absolute value).

  18. Comment on "Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake" [Phys. Plasmas 20, 102507 (2013)

    NASA Astrophysics Data System (ADS)

    Ryutov, D. D.; Cohen, R. H.; Rognlien, T. D.; Soukhanovskii, V. A.; Umansky, M. V.

    2014-05-01

    In the recently published paper "Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake" [Phys. Plasmas 20, 102507 (2013)], the authors raise interesting and important issues concerning divertor physics and design. However, the paper contains significant errors: (a) The conceptual framework used in it for the evaluation of divertor "quality" is reduced to the assessment of the magnetic field structure in the outer Scrape-Off Layer. This framework is incorrect because processes affecting the pedestal, the private flux region and all of the divertor legs (four, in the case of a snowflake) are an inseparable part of divertor operation. (b) The concept of the divertor index focuses on only one feature of the magnetic field structure and can be quite misleading when applied to divertor design. (c) The suggestion to rename the divertor configurations experimentally realized on NSTX (National Spherical Torus Experiment) and DIII-D (Doublet III-D) from snowflakes to X-divertors is not justified: it is not based on comparison of these configurations with the prototypical X-divertor, and it ignores the fact that the NSTX and DIII-D poloidal magnetic field geometries fit very well into the snowflake "two-null" prescription.

  19. Design, R&D and commissioning of EAST tungsten divertor

    NASA Astrophysics Data System (ADS)

    Yao, D. M.; Luo, G. N.; Zhou, Z. B.; Cao, L.; Li, Q.; Wang, W. J.; Li, L.; Qin, S. G.; Shi, Y. L.; Liu, G. H.; Li, J. G.

    2016-02-01

    After commissioning in 2005, the EAST superconducting tokamak had been operated with its water cooled divertors for eight campaigns up to 2012, employing graphite as plasma facing material. With increase in heating power over 20 MW in recent years, the heat flux going to the divertors rises rapidly over 10 MW m-2 for steady state operation. To accommodate the rapid increasing heat load in EAST, the bolting graphite tile divertor must be upgraded. An ITER-like tungsten (W) divertor has been designed and developed; and firstly used for the upper divertor of EAST. The EAST upper W divertor is modular structure with 80 modules in total. Eighty sets of W/Cu plasma-facing components (PFC) with each set consisting of an outer vertical target (OVT), an inner vertical target (IVT) and a DOME, are attached to 80 stainless steel cassette bodies (CB) by pins. The monoblock W/Cu-PFCs have been developed for the strike points of both OVT and IVT, and the flat type W/Cu-PFCs for the DOME and the baffle parts of both OVT and IVT, employing so-called hot isostatic pressing (HIP) technology for tungsten to CuCrZr heat sink bonding, and electron beam welding for CuCrZr to CuCrZr and CuCrZr to other material bonding. Both monoblock and flat type PFC mockups passed high heat flux (HHF) testing by means of electron beam facilities. The 80 divertor modules were installed in EAST in 2014 and results of the first commissioning are presented in this paper.

  20. The edge plasma and divertor in TIBER

    SciTech Connect

    Barr, W.L.

    1987-10-16

    An open divertor configuration has been adopted for TIBER. Most recent designs, including DIII-D, NET and CIT use open configurations and rely on a dense edge plasma to shield the plasma from the gas produced at the neutralizer plate. Experiments on ASDEX, PDX, D-III, and recently on DIII-D have shown that a dense edge plasma can be produced by re-ionizing most of the gas produced at the plate. This high recycling mode allows a large flux of particles to carry the heat to the plate, so that the mean energy per particle can be low. Erosion of the plate can be greatly reduced if the average impact energy of the ions at the plate can be reduced to near or below the threshold for sputtering of the plate material. The present configuration allows part of the flux of edge plasma ions to be neutralized at the entrance to the pumping duct so that helium is pumped as well as hydrogen. 7 refs., 3 figs.

  1. Carbon flows in attached divertor plasmas

    SciTech Connect

    Isler, R.C.; Brooks, N.H.; West, W.P.; Porter, G.D. |; The DIII-D Divertor Team

    1999-05-01

    Parallel flow velocities of carbon ions in the DIII-D divertor [J. Luxon {ital et al.}, {ital Plasma Physics Controlled Nuclear Fusion Research}, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159; S. L. Allen {ital et al.}, {ital Controlled Fusion and Plasma Physics}, 1987 (Proc. 24th European Conf. Berchtesgaden, 1997), Vol. 21 A, Part III, p. 1129] have been studied under various operating conditions: L-mode (low-confinement mode), H-mode (high-confinement mode) with low-frequency ELMs (edge-localized modes), and H-mode with high-frequency ELMs. Both normal and reversed flows (toward the target plate and away from the target plate, respectively) are observed under all conditions, with the reversed speeds being as much as a factor of four greater than normal speeds. Magnitudes are approximately the same for L-mode and H-mode operation with high-frequency ELMs. In H-mode conditions with low-frequency ELMs, normal velocities are frequently observed to decline while reversed velocities increase in comparison to the other two conditions. {copyright} {ital 1999 American Institute of Physics.}

  2. Finger Forces in Clarinet Playing.

    PubMed

    Hofmann, Alex; Goebl, Werner

    2016-01-01

    Clarinettists close and open multiple tone holes to alter the pitch of the tones. Their fingering technique must be fast, precise, and coordinated with the tongue articulation. In this empirical study, finger force profiles and tongue techniques of clarinet students (N = 17) and professional clarinettists (N = 6) were investigated under controlled performance conditions. First, in an expressive-performance task, eight selected excerpts from the first Weber Concerto were performed. These excerpts were chosen to fit in a 2 × 2 × 2 design (register: low-high; tempo: slow-fast, dynamics: soft-loud). There was an additional condition controlled by the experimenter, which determined the expression levels (low-high) of the performers. Second, a technical-exercise task, an isochronous 23-tone melody was designed that required different effectors to produce the sequence (finger-only, tongue-only, combined tongue-finger actions). The melody was performed in three tempo conditions (slow, medium, fast) in a synchronization-continuation paradigm. Participants played on a sensor-equipped Viennese clarinet, which tracked finger forces and reed oscillations simultaneously. From the data, average finger force (F mean ) and peak force (F max ) were calculated. The overall finger forces were low (F mean = 1.17 N, F max = 3.05 N) compared to those on other musical instruments (e.g., guitar). Participants applied the largest finger forces during the high expression level performance conditions (F mean = 1.21 N). For the technical exercise task, timing and articulation information were extracted from the reed signal. Here, the timing precision of the fingers deteriorated the timing precision of the tongue for combined tongue-finger actions, especially for faster tempi. Although individual finger force profiles were overlapping, the group of professional players applied less finger force overall (F mean = 0.54 N). Such sensor instruments provide useful insights into player

  3. Finger Forces in Clarinet Playing.

    PubMed

    Hofmann, Alex; Goebl, Werner

    2016-01-01

    Clarinettists close and open multiple tone holes to alter the pitch of the tones. Their fingering technique must be fast, precise, and coordinated with the tongue articulation. In this empirical study, finger force profiles and tongue techniques of clarinet students (N = 17) and professional clarinettists (N = 6) were investigated under controlled performance conditions. First, in an expressive-performance task, eight selected excerpts from the first Weber Concerto were performed. These excerpts were chosen to fit in a 2 × 2 × 2 design (register: low-high; tempo: slow-fast, dynamics: soft-loud). There was an additional condition controlled by the experimenter, which determined the expression levels (low-high) of the performers. Second, a technical-exercise task, an isochronous 23-tone melody was designed that required different effectors to produce the sequence (finger-only, tongue-only, combined tongue-finger actions). The melody was performed in three tempo conditions (slow, medium, fast) in a synchronization-continuation paradigm. Participants played on a sensor-equipped Viennese clarinet, which tracked finger forces and reed oscillations simultaneously. From the data, average finger force (F mean ) and peak force (F max ) were calculated. The overall finger forces were low (F mean = 1.17 N, F max = 3.05 N) compared to those on other musical instruments (e.g., guitar). Participants applied the largest finger forces during the high expression level performance conditions (F mean = 1.21 N). For the technical exercise task, timing and articulation information were extracted from the reed signal. Here, the timing precision of the fingers deteriorated the timing precision of the tongue for combined tongue-finger actions, especially for faster tempi. Although individual finger force profiles were overlapping, the group of professional players applied less finger force overall (F mean = 0.54 N). Such sensor instruments provide useful insights into player

  4. [Multiple finger geodes in children].

    PubMed

    Hoeffel, J C; Oprisescu, B; Bresson, A; Ploier, R; Vidailhet, M

    1993-06-01

    Three pediatric patients with multiple geodes in the fingers are reported. This condition occurs mainly between one and three years and at seven years of age and is more common in winter. Affected fingers are swollen. Roentgenograms disclose several small lucent defects which are usually located in the middle phalanx. Several fingers are usually involved. The erythrocyte sedimentation rate is increased in virtually every case. Resolution occurs spontaneously within a few weeks or months. There is no tendency towards recurrence. Although the condition is inflammatory, exposure to cold is probably a precipitating factor.

  5. Finger-Circumference-Measuring Device

    NASA Technical Reports Server (NTRS)

    Le, Suy

    1995-01-01

    Easy-to-use device quickly measures circumference of finger (including thumb) on human hand. Includes polytetrafluoroethylene band 1/8 in. wide, bent into loop and attached to tab that slides on scale graduated in millimeters. Sliding tab preloaded with constant-force tension spring, which pulls tab toward closure of loop. Designed to facilitate measurements at various points along fingers to obtain data for studies of volumetric changes of fingers in microgravity. Also used in normal Earth gravity studies of growth and in assessment of diseases like arthritis.

  6. Upgraded divertor Thomson scattering system on DIII-D

    NASA Astrophysics Data System (ADS)

    Glass, F.; Carlstrom, T. N.; Du, D.; McLean, A. G.; Taussig, D. A.; Boivin, R. L.

    2016-11-01

    A design to extend the unique divertor Thomson scattering system on DIII-D to allow measurements of electron temperature and density in high triangularity plasmas is presented. Access to this region is selectable on a shot-by-shot basis by redirecting the laser beam of the existing divertor Thomson system inboard — beneath the lower floor using a moveable, high-damage threshold, in-vacuum mirror — and then redirecting again vertically. The currently measured divertor region remains available with this mirror retracted. Scattered light is collected from viewchords near the divertor floor using in-vacuum, high temperature optical elements and relayed through the port window, before being coupled into optical fiber bundles. At higher elevations from the floor, measurements are made by dynamically re-focusing the existing divertor system collection optics. Nd:YAG laser timing, analysis of the scattered light spectrum via polychromators, data acquisition, and calibration are all handled by existing systems or methods of the current multi-pulse Thomson scattering system. Existing filtered polychromators with 7 spectral channels are employed to provide maximum measurement breadth (Te in the range of 0.5 eV-2 keV, ne in the range of 5 × 1018-1 × 1021 m3) for both low Te in detachment and high Te measurement up beyond the separatrix.

  7. Divertor and midplane materials evaluation system in DIII-D

    NASA Astrophysics Data System (ADS)

    Wong, C. P. C.; Rudakov, D. L.; Allain, J. P.; Bastasz, R. J.; Brooks, N. H.; Brooks, J. N.; Doerner, R. P.; Evans, T. E.; Hassanein, A.; Jacob, W.; Krieger, K.; Litnovsky, A.; McLean, A. G.; Philipps, V.; Pigarov, A. Yu.; Wampler, W. R.; Watkins, J. G.; West, W. P.; Whaley, J.; Wienhold, P.

    2007-06-01

    The Divertor Materials Evaluation System (DiMES) at General Atomics has successfully advanced the understanding of plasma surface interaction phenomena involving ITER-relevant materials and has been utilized for advanced diagnostic designs in the lower divertor of DIII-D. This paper describes a series of recent successful experiments. These include the study of carbon deposition in gaps and metallic mirrors as a function of temperature, study of dust migration from the divertor, study of methane injection in order to benchmark chemical sputtering diagnostics, and the measurement of charge exchange neutrals with a hydrogen sensor. In concert with the modification of the lower divertor of DIII-D, the DiMES sample vertical location was modified to match the raised divertor floor. The new Mid-plane Material Exposure Sample (MiMES) design will also be presented. MiMES will allow the study and measurement of erosion and redeposition of material at the outboard mid-plane of DIII-D, including effects from convective transport. We will continue to expose relevant materials and advanced diagnostics to different plasma configurations under various operational regimes, including material erosion and redeposition experiments, and gaps and mirror exposures at elevated temperature.

  8. Neural correlates of finger gnosis.

    PubMed

    Rusconi, Elena; Tamè, Luigi; Furlan, Michele; Haggard, Patrick; Demarchi, Gianpaolo; Adriani, Michela; Ferrari, Paolo; Braun, Christoph; Schwarzbach, Jens

    2014-07-01

    Neuropsychological studies have described patients with a selective impairment of finger identification in association with posterior parietal lesions. However, evidence of the role of these areas in finger gnosis from studies of the healthy human brain is still scarce. Here we used functional magnetic resonance imaging to identify the brain network engaged in a novel finger gnosis task, the intermanual in-between task (IIBT), in healthy participants. Several brain regions exhibited a stronger blood oxygenation level-dependent (BOLD) response in IIBT than in a control task that did not explicitly rely on finger gnosis but used identical stimuli and motor responses as the IIBT. The IIBT involved stronger signal in the left inferior parietal lobule (IPL), bilateral precuneus (PCN), bilateral premotor cortex, and left inferior frontal gyrus. In all regions, stimulation of nonhomologous fingers of the two hands elicited higher BOLD signal than stimulation of homologous fingers. Only in the left anteromedial IPL (a-mIPL) and left PCN did signal strength decrease parametrically from nonhomology, through partial homology, to total homology with stimulation delivered synchronously to the two hands. With asynchronous stimulation, the signal was stronger in the left a-mIPL than in any other region, possibly indicating retention of task-relevant information. We suggest that the left PCN may contribute a supporting visuospatial representation via its functional connection to the right PCN. The a-mIPL may instead provide the core substrate of an explicit bilateral body structure representation for the fingers that when disrupted can produce the typical symptoms of finger agnosia. PMID:24990921

  9. Modeling of Alcator C-Mod Divertor Baffling Experiments

    SciTech Connect

    D. P. Stotler; C. S. Pitcher; C. J. Boswell; T. K. Chung; B. LaBombard; B. Lipschultz; J. L. Terry; R. J. Kanzleiter

    2000-11-29

    A specific Alcator C-Mod discharge from the series of divertor baffling experiments is simulated with the DEGAS 2 Monte Carlo neutral transport code. A simple two-point plasma model is used to describe the plasma variation between Langmuir probe locations. A range of conductances for the bypass between the divertor plenum and the main chamber are considered. The experimentally observed insensitivity of the neutral current flowing through the bypass and of the D alpha emissions to the magnitude of the conductance is reproduced. The current of atoms in this regime is being limited by atomic physics processes and not the bypass conductance. The simulated trends in the divertor pressure, bypass current, and D alpha emission agree only qualitatively with the experimental measurements, however. Possible explanations for the quantitative differences are discussed.

  10. A novel approach to magnetic divertor configuration design

    NASA Astrophysics Data System (ADS)

    Blommaert, M.; Baelmans, M.; Dekeyser, W.; Gauger, N. R.; Reiter, D.

    2015-08-01

    Divertor exhaust system design and analysis tools are crucial to evolve from experimental fusion reactors towards commercial power plants. In addition to material research and dedicated vessel geometry design, improved magnetic configurations can contribute to sustaining the diverted heat loads. Yet, computational design of the magnetic divertor is a challenging process involving a magnetic equilibrium solver, a plasma edge grid generator and a computationally demanding plasma edge simulation. In this paper, an integrated approach to efficient sensitivity calculations is discussed and applied to a set of slightly reduced divertor models. Sensitivities of target heat load performance to the shaping coil currents are directly evaluated. Using adjoint methods, the cost for a sensitivity evaluation is reduced to about two times the simulation cost of one specific configuration. Further, the use of these sensitivities in an optimal design framework is illustrated by a case with realistic Joint European Torus (JET) configurational parameters.

  11. Plasma transport in a simulated magnetic-divertor configuration

    SciTech Connect

    Strawitch, C. M.

    1981-03-01

    The transport properties of plasma on magnetic field lines that intersect a conducting plate are studied experimentally in the Wisconsin internal ring D.C. machine. The magnetic geometry is intended to simulate certain aspects of plasma phenomena that may take place in a tokamak divertor. It is found by a variety of measurements that the cross field transport is non-ambipolar; this may have important implications in heat loading considerations in tokamak divertors. The undesirable effects of nonambipolar flow make it preferable to be able to eliminate it. However, we find that though the non-ambipolarity may be reduced, it is difficult to eliminate entirely. The plasma flow velocity parallel to the magnetic field is found to be near the ion acoustic velocity in all cases. The experimental density and electron temperature profiles are compared to the solutions to a one dimensional transport model that is commonly used in divertor theory.

  12. Turbulence studies in Tokamak boundary plasmas with realistic divertor geometry

    SciTech Connect

    Xu, X.Q.

    1998-10-14

    Results are presented from the 3D nonlocal electromagnetic turbulence code BOUT [1] and the linearized shooting code BAL[2] to study turbulence in tokamak boundary plasmas and its relationship to the L-H transition, in a realistic divertor plasma geometry. The key results include: (1) the identification of the dominant, resistive X-point mode in divertor geometry and (2) turbulence suppression in the L-H transition by shear in the ExB drift speed, ion diamagnetism and finite polarization. Based on the simulation results, a parameterization of the transport is given that includes the dependence on the relevant physical parameters.

  13. An analytic model for flow reversal in divertor plasmas

    SciTech Connect

    Cooke, P.I.H.; Prinja, A.K.

    1987-04-01

    An analytic model is developed and used to study the phenomenon of flow reversal which is observed in two-dimensional simulations of divertor plasmas. The effect is shown to be caused by the radial spread of neutral particles emitted from the divertor target which can lead to a strong peaking of the ionization source at certain radial locations. The results indicate that flow reversal over a portion of the width of the scrape-off layer is inevitable in high recycling conditions. Implications for impurity transport and particle removal in reactors are discussed.

  14. Non-ambipolar transport in a magnetic divertor

    SciTech Connect

    Strawitch, C M; Emmert, G A

    1980-02-01

    Plasma transport is studied in a simulated magnetic divertor in the Wisconsin single ring DC machine. The transport perpendicular and parallel to the magnetic field is shown to be non-ambipolar by a variety of measurements, but can be forced to be ambipolar by an appropriately designed divertor target plate. The density profile in the scrape-off zone agrees with the predictions of a one-dimensional diffusion equation that assumes classical cross-field transport and plasma flow parallel to the field at the local ion acoustic velocity.

  15. Multi-finger interaction during involuntary and voluntary single finger force changes

    PubMed Central

    Martin, J.R.; Zatsiorsky, V.M.; Latash, M.L.

    2011-01-01

    Two types of finger interaction are characterized by positive co-variation (enslaving) or negative co-variation (error compensation) of finger forces. Enslaving reflects mechanical and neural connections among fingers, while error compensation results from synergic control of fingers to stabilize their net output. Involuntary and voluntary force changes by a finger were used to explore these patterns. We hypothesized that synergic mechanisms will dominate during involuntary force changes, while enslaving will dominate during voluntary finger force changes. Subjects pressed with all four fingers to match a target force that was 10% of their maximum voluntary contraction (MVC). One of the fingers was unexpectedly raised 5.0 mm at a speed of 30.0 mm/s. During finger raising the subject was instructed “not to intervene voluntarily”. After the finger was passively lifted and a new steady-state achieved, subjects pressed down with the lifted finger, producing a pulse of force voluntarily. The data were analyzed in terms of finger forces and finger modes (hypothetical commands to fingers reflecting their intended involvement). The target finger showed an increase in force during both phases. In the involuntary phase, the target finger force changes ranged between 10.71 ± 1.89% MVC (I-finger) and 16.60 ± 2.26% MVC (L-finger). Generally, non-target fingers displayed a force decrease with a maximum amplitude of −1.49 ± 0.43% MVC (L-finger). Thus, during the involuntary phase, error compensation was observed – non-lifted fingers showed a decrease in force (as well as in mode magnitude). During the voluntary phase, enslaving was observed – non-target fingers showed an increase in force and only minor changes in mode magnitude. The average change in force of non-target fingers ranged from 21.83 ± 4.47% MVC for R-finger (M-finger task) to 0.71 ± 1.10 % MVC for L-finger (I-finger task). The average change in mode of non-target fingers was between −7.34 ± 19

  16. Thermal Analysis of the Divertor Primary Heat Transfer System Piping During the Gas Baking Process

    SciTech Connect

    Yoder Jr, Graydon L; Harvey, Karen; Ferrada, Juan J

    2011-02-01

    A preliminary analysis has been performed examining the temperature distribution in the Divertor Primary Heat Transfer System (PHTS) piping and the divertor itself during the gas baking process. During gas baking, it is required that the divertor reach a temperature of 350 C. Thermal losses in the piping and from the divertor itself require that the gas supply temperature be maintained above that temperature in order to ensure that all of the divertor components reach the required temperature. The analysis described in this report was conducted in order to estimate the required supply temperature from the gas heater.

  17. Neutral gas compression in the Alcator C-Mod divertor, experimental observations

    SciTech Connect

    Niemczewski, A.; LaBombard, B.; Lipschultz, B.; McCracken, G.

    1994-11-01

    One of the high heat flux solutions envisioned for ITER is the gas target divertor. This scheme requires high neutral pressure to be sustained in the divertor chamber with a minimal effect on the pressure in the main tokamak chamber (i.e. high gas compression). The neutral gas compression has been studied in the Alcator C-Mod closed divertor under various central and edge plasma conditions. The neutral pressure measured by a fast, in-situ, ionization gauge, installed behind the divertor target plate was compared with the midplane pressure, measured by a shielded Bayard-Alpert gauge. Divertor pressures up to 30 mTorr with compression factors p{sub div}/p{sub mid} {le} 70 have been observed. It has been found that the neutral pressure in the divertor does not depend strongly on the fueling location but rather on the core plasma density and the resulting divertor plasma regime. Divertor detachment leads to a considerable drop in the compression ratio, suggesting a partial {open_quotes}unplugging{close_quotes} of the divertor volume. An examination of the local particle flux balance in the divertor indicates that the single most important factor determining divertor pressure and compression is the private-flux plasma channel opacity to neutrals.

  18. Taming the plasma-material interface with the snowflake divertor.

    SciTech Connect

    Soukhanovskii, V A

    2015-04-24

    Experiments in several tokamaks have provided increasing support for the snowflake configuration as a viable tokamak heat exhaust concept. This white paper summarizes the snowflake properties predicted theoretically and studied experimentally, and identifies outstanding issues to be resolved in existing and future facilities before the snowflake divertor can qualify for the reactor interface.

  19. Line Shapes and Opacity Studies in Divertor Plasmas

    SciTech Connect

    Rosato, J.

    2008-10-22

    Large or dense divertor plasmas of magnetic fusion devices can be optically thick to the resonance lines of the hydrogen isotopes. In this work we examine the sensitivity of the line radiation transport to the detailed structure of the spectral profiles.

  20. Mechanical Design of the NSTX Liquid Lithium Divertor

    SciTech Connect

    R. Ellis, R. Kaita, H. Kugel, G. Paluzzi, M. Viola and R. Nygren

    2009-02-19

    The Liquid Lithium Divertor (LLD) on NSTX will be the first test of a fully-toroidal liquid lithium divertor in a high-power magnetic confinement device. It will replace part of the lower outboard divertor between a specified inside and outside radius, and ultimately provide a lithium surface exposed to the plasma with enough depth to absorb a significant particle flux. There are numerous technical challenges involved in the design. The lithium layer must be as thin as possible, and maintained at a temperature between 200 and 400 degrees Celsius to minimize lithium evaporation. This requirement leads to the use of a thick copper substrate, with a thin stainless steel layer bonded to the plasma-facing surface. A porous molybdenum layer is then plasma-sprayed onto the stainless steel, to provide a coating that facilitates full wetting of the surface by the liquid lithium. Other challenges include the design of a robust, vacuumcompatible heating and cooling system for the LLD. Replacement graphite tiles that provided the proper interface between the existing outer divertor and the LLD also had to be designed, as well as accommodation for special LLD diagnostics. This paper describes the mechanical design of the LLD, and presents analyses showing the performance limits of the LLD.

  1. Theoretical design of a compact energy recovering divertor

    NASA Astrophysics Data System (ADS)

    Baver, D. A.

    2015-11-01

    An energy recovering divertor (ERD) is a type of plasma direct converter (PDC) designed to fit in the divertor channel of a tokamak. Such a device reduces the heat load to the divertor plate by converting a portion of it into electrical energy. This recovered energy can then be used for auxiliary heating and current drive, fundamentally altering the relationship between scientific and engineering breakeven and reducing dependence on bootstrap current. Previous work on the ERD concept focused on amplification of Alfven waves in a manner similar to a free-electron laser. While conceptually straightforward, this concept was also bulky, thus limiting its applicability to existing tokamak experiments. A design is presented for an ERD based on sheath-localized waves. This makes possible a device sufficiently compact to fit in the divertor channel of many existing tokamak experiments, and moreover requires no new shaping coils to achieve the desired magnetic geometry or topology. In addition, incidental advantages of this concept will be discussed.

  2. Mesofluidic controlled robotic or prosthetic finger

    SciTech Connect

    Lind, Randall F; Jansen, John F; Love, Lonnie J

    2013-11-19

    A mesofluidic powered robotic and/or prosthetic finger joint includes a first finger section having at least one mesofluidic actuator in fluid communication with a first actuator, a second mesofluidic actuator in fluid communication with a second actuator and a second prosthetic finger section pivotally connected to the first finger section by a joint pivot, wherein the first actuator pivotally cooperates with the second finger to provide a first mechanical advantage relative to the joint point and wherein the second actuator pivotally cooperates with the second finger section to provide a second mechanical advantage relative to the joint point.

  3. Repair of webbed fingers or toes

    MedlinePlus

    ... surgery is more complicated when it involves fused bones, nerves, blood vessels, and tendons. ... of the fingers or toes Injuries to the blood vessels, tendons, or bones in the fingers Call your doctor if you ...

  4. Diagnostic options for radiative divertor feedback control on NSTX-Ua)

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Gerhardt, S. P.; Kaita, R.; McLean, A. G.; Raman, R.

    2012-10-01

    A radiative divertor technique is used in present tokamak experiments and planned for ITER to mitigate high heat loads on divertor plasma-facing components (PFCs) to prevent excessive material erosion and thermal damage. In NSTX, a large spherical tokamak with lithium-coated graphite PFCs and high divertor heat flux (qpeak ⩽ 15 MW/m2), radiative divertor experiments have demonstrated a significant reduction of divertor peak heat flux simultaneously with good core H-mode confinement using pre-programmed D2 or CD4 gas injections. In this work diagnostic options for a new real-time feedback control system for active radiative divertor detachment control in NSTX-U, where steady-state peak divertor heat fluxes are projected to reach 20-30 MW/m2, are discussed. Based on the NSTX divertor detachment measurements and analysis, the control diagnostic signals available for NSTX-U include divertor radiated power, neutral pressure, spectroscopic deuterium recombination signatures, infrared thermography of PFC surfaces, and thermoelectric scrape-off layer current. In addition, spectroscopic "security" monitoring of possible confinement or pedestal degradation is recommended. These signals would be implemented in a digital plasma control system to manage the divertor detachment process via an actuator (impurity gas seeding rate).

  5. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.34 Finger Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural...

  6. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.34 Finger Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural...

  7. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.34 Finger Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural...

  8. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... THE TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.34 Finger Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural...

  9. 27 CFR 9.34 - Finger Lakes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.34 Finger Lakes. (a) Name. The name of the viticultural area described in this section is “Finger Lakes.” (b) Approved maps. The appropriate maps for determining the boundaries of the Finger Lakes viticultural...

  10. Divertor heat and particle control experiments on the DIII-D tokamak

    SciTech Connect

    Mahdavi, M.A; Baker, D.R.; Allen, S.L.

    1994-05-01

    In this paper we present a summary of recent DIII-D divertor physics activity and plans for future divertor upgrades. During the past year, DIII-D experimental effort was focused on areas of active heat and particle control and divertor target erosion studies. Using the DIII-D Advanced Divertor system we have succeeded for the first time to control the plasma density and demonstrate helium exhaust in H-mode plasmas. Divertor heat flux control by means of D{sub 2} gas puffing and impurity injection were studied separately and in, both cases up to a factor of five reduction of the divertor peak heat flux was observed. Using the DiMES sample transfer system we have obtained erosion data on various material samples in well diagnosed plasmas and compared the results with predictions of numerical models.

  11. The influence of the radial particle transport on the divertor plasma detachment

    NASA Astrophysics Data System (ADS)

    Hoshino, K.; Shimizu, K.; Takizuka, T.; Asakura, N.; Nakano, T.

    2015-08-01

    Divertor plasma detachment is the most promising candidate to reduce the divertor heat load in fusion reactors. Present understanding of detachment physics is not sufficient to adequately reproduce experimental observations. Understanding and control of detachment physics is indispensable to design the divertor in future machines. To improve the quality of divertor modeling and reveal limitations of the detachment physics built into state-of-the-art codes, an integrated divertor code SONIC has been applied to modeling of the JT-60U detached divertor plasma. In this study, the radial diffusion coefficient in the private region or the far SOL region is increased to investigate the influence of radial plasma transport on detachment characteristics. Saturation of the reduction in ion flux after roll-over is improved by the radial transport enhancement, while the radial profile at the mid-plane agreed with the experimental data.

  12. Tungsten spectroscopy relevant to the diagnostics development of ITER divertor plasmas

    SciTech Connect

    Clementson, J; Beiersdorfer, P; Magee, E W; McLean, H S; Wood, R D

    2009-12-01

    The ITER tokamak will have tungsten divertor tiles and, consequently, the divertor plasmas are expected to contain tungsten ions. The spectral emission from these ions can serve to diagnose the divertor for plasma parameters such as tungsten concentrations, densities, ion and electron temperatures, and flow velocities. The ITER divertor plasmas will likely have densities around 10{sup 14-15} cm{sup -3} and temperatures below 150 eV. These conditions are similar to the plasmas at the Sustained Spheromak Physics Experiment (SSPX) in Livermore. To simulate ITER divertor plasmas, a tungsten impurity was introduced into the SSPX spheromak by prefilling it with tungsten hexacarbonyl prior to the usual hydrogen gas injection and initiation of the plasma discharge. The possibility of using the emission from low charge state tungsten ions to diagnose tokamak divertor plasmas has been investigated using a high-resolution extreme ultraviolet spectrometer.

  13. An automated approach to magnetic divertor configuration design

    NASA Astrophysics Data System (ADS)

    Blommaert, M.; Dekeyser, W.; Baelmans, M.; Gauger, N. R.; Reiter, D.

    2015-01-01

    Automated methods based on optimization can greatly assist computational engineering design in many areas. In this paper an optimization approach to the magnetic design of a nuclear fusion reactor divertor is proposed and applied to a tokamak edge magnetic configuration in a first feasibility study. The approach is based on reduced models for magnetic field and plasma edge, which are integrated with a grid generator into one sensitivity code. The design objective chosen here for demonstrative purposes is to spread the divertor target heat load as much as possible over the entire target area. Constraints on the separatrix position are introduced to eliminate physically irrelevant magnetic field configurations during the optimization cycle. A gradient projection method is used to ensure stable cost function evaluations during optimization. The concept is applied to a configuration with typical Joint European Torus (JET) parameters and it automatically provides plausible configurations with reduced heat load.

  14. Detached divertor operation in DIII-D helium plasmas

    SciTech Connect

    Hill, D. N., LLNL

    1998-05-01

    This paper presents results from operating helium plasmas in DIII-D in which helium gas puffing is used to reduce the peak divertor heat flux by factors of four or more. The threshold density for achieving these conditions is nearly the same as for deuterium plasmas, which is surprising given the fact that lack of chemical sputtering reduces the carbon concentration in the plasma by more than a factor of five. Spectroscopic analysis shows that helium becomes the primary radiation in these plasmas, which is possible because, unlike carbon, it is the primary species present. These plasmas differ from the usual partially detached divertor (PDD) plasmas in that there is no concomitant reduction in target plate ion flux with target plate heat flux in the scrape off later outside the separatrix.

  15. Preliminary activation calculations for the Poloidal Divertor Experiment

    SciTech Connect

    Judd, J.L.; Scott, A.J.; Nigg, D.W.; Bohn, T.S.

    1981-01-01

    The Poloidal Divertor Experiment (PDX) tokamak is being operated by the Princeton Plasma Physics Laboratory (PPPL) to study plasma cross section shaping, high power neutral beam heating, and divertor control of plasma impurities in tokamaks. Experiments to date have been performed at relatively low power, but with 6 MW of neutral beam power eventually available, high D-D plasma reaction rates are expected that will yield up to 10/sup 15/ 2.45-MeV neutrons per pulse. This neutron emission level is high enough to cause significant neutron-induced machine activation that will limit the occupancy time of personnel entering the room to repair or change parts. The dose rate depends on the location in the room and, of course, the pulsing history prior to entry. This paper describes one-dimensional activation calculations that have been done for PDX to provide preliminary dose rate information for various times after shutdown following one week of high power operation.

  16. Diagnosing transient plasma status: from solar atmosphere to tokamak divertor

    NASA Astrophysics Data System (ADS)

    Giunta, A. S.; Henderson, S.; O'Mullane, M.; Harrison, J.; Doyle, J. G.; Summers, H. P.

    2016-09-01

    This work strongly exploits the interdisciplinary links between astrophysical (such as the solar upper atmosphere) and laboratory plasmas (such as tokamak devices) by sharing the development of a common modelling for time-dependent ionisation. This is applied to the interpretation of solar flare data observed by the UVSP (Ultraviolet Spectrometer and Polarimeter), on-board the Solar Maximum Mission and the IRIS (Interface Region Imaging Spectrograph), and also to data from B2-SOLPS (Scrape Off Layer Plasma Simulations) for MAST (Mega Ampère Spherical Tokamak) Super-X divertor upgrade. The derived atomic data, calculated in the framework of the ADAS (Atomic Data and Analysis Structure) project, allow equivalent prediction in non-stationary transport regimes and transients of both the solar atmosphere and tokamak divertors, except that the tokamak evolution is about one thousand times faster.

  17. Acrylic Finger Prosthesis: A Case Report

    PubMed Central

    Bandela, Vinod; M, Bharathi; S V, Giridhar Reddy

    2014-01-01

    Hands basic function is to grasp, hold and manipulate items. Hand gesture is perhaps the most blatant example of non-verbal communication. Finger and partial finger amputations are most frequently encountered forms of partial hand loss. Common causes are traumatic injuries, congenital absence or malformations present great clinical challenges. In addition to immediate loss of grasp strength, finger absence may cause marked psychological trauma. Individuals who desire finger replacement usually have high expectation for the appearance of prosthesis. This clinical report portrays simple method to retain acrylic finger prosthesis. PMID:25302271

  18. The investigation of opacity in the JET tokomak divertor region

    NASA Astrophysics Data System (ADS)

    Lachin, Tracey

    The purpose of this thesis is to investigate Lyman line absorption by deuterium atoms in the divertor region of the JET tokamak for four high density, low temperature, detached plasma pulses. A collisional radiative model of deuterium level populations has been used to estimate the extent of Lybeta radiative absorption in the divertor along the same line of sight as a VUV spectrometer. This uses a first order escape probability method to evaluate the line escape probabilities and gives a self consistent model of the level populations and radiation field. These results are compared with experimental measurements of the branching ratio of Lybeta to Dalpha from the VUV spectrometer and various visible diagnostics. Both the theoretical and experimental results agree that opacity reduces the level of Lybeta emission from the divertor plasma. The effects of opacity on the ionisation and power balance of the plasma are examined for various conditions. The results of this investigation are compared with other theoretical work in the field. It is shown that the levels of opacity are not great enough to significantly alter the ionisation and power balance of the plasma for the conditions presently being created within the JET tokamak. The population code requires information about the background plasma. This can be provided by either a fluid code or an 'onion-skin' plasma simulation. Both models are used in this investigation and their levels of accuracy are compared. Finally, a brief investigation into the level of opacity in a future tokamak, ITER, is carried out using predicted plasma profiles. It is shown that opacity levels in the divertor region of the ITER tokamak could match those of JET and by creating highly detached plasmas could easily exceed these levels.

  19. Tokamak power exhaust with the snowflake divertor: Present results and outstanding issues

    DOE PAGES

    Soukhanovskii, V. A.; Xu, X.

    2015-09-15

    Here, a snowflake divertor magnetic configuration (Ryutov in Phys Plasmas 14(6):064502, 2007) with the second-order poloidal field null offers a number of possible advantages for tokamak plasma heat and particle exhaust in comparison with the standard poloidal divertor with the first-order null. Results from snowflake divertor experiments are briefly reviewed and future directions for research in this area are outlined.

  20. Impact of Finger Type in Fingerprint Authentication

    NASA Astrophysics Data System (ADS)

    Gafurov, Davrondzhon; Bours, Patrick; Yang, Bian; Busch, Christoph

    Nowadays fingerprint verification system is the most widespread and accepted biometric technology that explores various features of the human fingers for this purpose. In general, every normal person has 10 fingers with different size. Although it is claimed that recognition performance with little fingers can be less accurate compared to other finger types, to our best knowledge, this has not been investigated yet. This paper presents our study on the topic of influence of the finger type into fingerprint recognition performance. For analysis we employ two fingerprint verification software packages (one public and one commercial). We conduct test on GUC100 multi sensor fingerprint database which contains fingerprint images of all 10 fingers from 100 subjects. Our analysis indeed confirms that performance with small fingers is less accurate than performance with the others fingers of the hand. It also appears that best performance is being obtained with thumb or index fingers. For example, performance deterioration from the best finger (i.e. index or thumb) to the worst fingers (i.e. small ones) can be in the range of 184%-1352%.

  1. Does finger sense predict addition performance?

    PubMed

    Newman, Sharlene D

    2016-05-01

    The impact of fingers on numerical and mathematical cognition has received a great deal of attention recently. However, the precise role that fingers play in numerical cognition is unknown. The current study explores the relationship between finger sense, arithmetic and general cognitive ability. Seventy-six children between the ages of 5 and 12 participated in the study. The results of stepwise multiple regression analyses demonstrated that while general cognitive ability including language processing was a predictor of addition performance, finger sense was not. The impact of age on the relationship between finger sense, and addition was further examined. The participants were separated into two groups based on age. The results showed that finger gnosia score impacted addition performance in the older group but not the younger group. These results appear to support the hypothesis that fingers provide a scaffold for calculation and that if that scaffold is not properly built, it has continued differential consequences to mathematical cognition. PMID:26993292

  2. Analytical calculations for impurity seeded partially detached divertor conditions

    NASA Astrophysics Data System (ADS)

    Kallenbach, A.; Bernert, M.; Dux, R.; Reimold, F.; Wischmeier, M.; ASDEX Upgrade Team

    2016-04-01

    A simple analytical formula for the impurity seeded partially detached divertor operational point has been developed using 1D modelling. The inclusion of charge exchange momentum loss terms improves the 1D modelling for ASDEX Upgrade conditions and its extrapolation to larger devices. The investigations are concentrated around a partially detached divertor working point of low heat flux and an electron temperature around 2.5 eV at the target which are required to maintain low sputtering rates at a tungsten target plate. An experimental formula for the onset of detachment by nitrogen seeding in ASDEX Upgrade is well reproduced, and predictions are given for N, Ne and Ar seeding for variable device size. Moderate deviations from a linear {{P}\\text{sep}}/R size dependence of the detachment threshold are seen in the modelling caused by upstream radiation at longer field line lengths. The presented formula allows the prediction of the neutral gas or seed impurity pressure which is required to achieve partial detachment for a given {{P}\\text{sep}} in devices with a closed divertor similar to the geometry in ASDEX Upgrade.

  3. Particle recirculation in the ergodic divertor of Tore Supra

    NASA Astrophysics Data System (ADS)

    Gunn, J. P.; Azéroual, A.; Bécoulet, M.; Bucalossi, J.; Bush, C.; Corre, Y.; Costanzo, L.; Devynck, P.; Ghendrih, Ph; Gianella, R.; Grisolia, C.; Guirlet, R.; Grosman, A.; Laugier, F.; Loarer, T.; Martin, G.; Meslin, B.; Monier-Garbet, P.; Moulin, D.; Pascal, J.-Y.; Pégourié, B.; Reichle, R.; Saint-Laurent, F.; Schunke, B.; Vallet, J.-C.

    1999-12-01

    The present paper addresses the issue of particle recirculation in discharges where low-energy flux to ergodic divertor target plates is achieved in highly-radiating detached ohmic plasmas. Plasma temperature and particle flux are measured by flush-mounted probes in the divertor plates and by an upstream fast scanning Mach probe. The scalings with core density of the ion flux and electron temperature are well described by the simple two-point model used in axisymmetric poloidal divertors. The detachment signature is a pressure drop that occurs when the edge temperature falls below 10 eV. The parallel ion flux gradient is always positive, indicating that recombination is unlikely to play an important role in detachment. Visible spectroscopy of a neutralizer plate shows that attainment of cold detached plasmas near the density limit coincides with an abrupt increase of fuelling efficiency for both deuterium and impurities. A feedback algorithm based on real-time Langmuir probe measurements has been developed to monitor detachment and avoid disruptions.

  4. Power distribution in the snowflake divertor in TCV

    NASA Astrophysics Data System (ADS)

    Reimerdes, H.; Canal, G. P.; Duval, B. P.; Labit, B.; Lunt, T.; Vijvers, W. A. J.; Coda, S.; De Temmerman, G.; Morgan, T. W.; Nespoli, F.; Tal, B.; the TCV Team

    2013-12-01

    TCV experiments demonstrate the basic power exhaust properties of the snowflake (SF) plus and SF minus divertor configurations by measuring the heat fluxes at each of their four divertor legs. The measurements indicate an enhanced transport into the private flux region and a reduction of peak heat fluxes compared to a similar single null configuration. There are indications that this enhanced transport cannot be explained by the modified field line geometry alone and likely requires an additional or enhanced cross-field transport channel. The measurements, however, do not show a broadening of the scrape-off layer (SOL) and, hence, no increased cross-field transport in the common flux region. The observations are consistent with the spatial limitation of several characteristic SF properties, such as a low poloidal magnetic field in the divertor region and a long connection length to the inner part of the SOL closest to the separatrix. Although this limitation is typical in a medium sized tokamak like TCV, it does not apply to significantly larger devices where the SF properties are enhanced across the entire expected extent of the SOL.

  5. Fast reciprocating Langmuir probe for the DIII-D divertor

    NASA Astrophysics Data System (ADS)

    Watkins, J. G.; Hunter, J.; Tafoya, B.; Ulrickson, M.; Watson, R. D.; Moyer, R. A.; Cuthbertson, J. W.; Gunner, G.; Lehmer, R.; Luong, P.; Hill, D. N.; Mascaro, M.; Robinson, J. I.; Snider, R.; Stambaugh, R.

    1997-01-01

    A new reciprocating Langmuir probe was used to measure density and temperature profiles, ion flow, and potential fluctuation levels from the lower divertor floor up to the X point on the DIII-D Tokamak. This probe is designed to make fast (2 kHz swept, 20 kHz Mach, 500 kHz Vfloat) measurements with 2 mm spatial resolution in the region where the largest gradients on the plasma open flux tubes are found and therefore provide the best benchmarks for scrap-off layer and divertor numerical models. Profiles are constructed using the 300 ms time history of the probe measurements during the 25 cm reciprocating stroke. Both single and double null plasmas can be measured and compared with a 20 Hz divertor Thomson scattering system. The probe head is constructed of four different kinds of graphite to optimize the electrical and thermal characteristics. Electrically insulated pyrolytic graphite rings act as a heat shield to absorb the plasma heat flux on the probe shaft and are mounted on a carbon/carbon composite core for mechanical strength. The Langmuir probe sampling tips are made of a linear carbon fiber composite. The mechanical, electrical, data acquisition, and power supply systems will be described. Initial measurements will also be presented.

  6. Impurity Transport in a Simulated Gas Target Divertor

    NASA Astrophysics Data System (ADS)

    Blush, L. M.; Luckhardt, S.; Seraydarian, R.; Whyte, D.; Conn, R. W.; Schmitz, L.

    1997-11-01

    Previous simulated gas target divertor experiments in the PISCES-A linear plasma device (n <= 3 × 10^19 m-3, kTe <= 20 eV) indicated enhanced impurity retention near the target in comparison to a high recycling divertor regime. A 1 1\\over2-D fluid modeling code suggested that impurities are impeded from transporting away from the target by friction with the neutral and ionized hydrogen. In recent experiments with a PISCES-A ``slot-type'' divertor configuration, we have implemented a spectroscopic detection system to measure the axial density profiles of several impurity charge states. Moreover, we envision adding two extended cylindrical baffles spanning a pumped vacuum section to achieve strong differential pumping. This arrangement will isolate the plasma source from the gas target region and allow us to seed the background hydrogen plasma with higher impurities concentrations and investigate a regime dominated by impurity radiation. In preliminary design experiments, PISCES-A was successfully operated with an electrically isolated, copper baffle (d=5 cm, l=33.5 cm) mounted to reduce the vacuum conductance between the source and target regions. This work supported by US-DoE contract DE-FG03-95ER-54301.

  7. Island Divertor Plate Modeling for the Compact Toroidal Hybrid Experiment

    NASA Astrophysics Data System (ADS)

    Hartwell, G. J.; Massidda, S. D.; Ennis, D. A.; Knowlton, S. F.; Maurer, D. A.; Bader, A.

    2015-11-01

    Edge magnetic island divertors can be used as a method of plasma particle and heat exhaust in long pulse stellarator experiments. Detailed power loading on these structures and its relationship to the long connection length scrape off layer physics is a new Compact Toroidal Hybrid (CTH) research thrust. CTH is a five field period, l = 2 torsatron with R0 = 0 . 75 m, ap ~ 0 . 2 m, and | B | <= 0 . 7 T. For these studies CTH is configured as a pure stellarator using a 28 GHz, 200 kW gyrotron operating at 2nd harmonic for ECRH. We report the results of EMC3-EIRENE modeling of divertor plates near magnetic island structures. The edge rotational transform is varied by adjusting the ratio of currents in the helical and toroidal field coils. A poloidal field coil adjusts the shear of the rotational transform profile, and width of the magnetic island, while the phase of the island is rotated with a set of five error coils producing an n = 1 perturbation. For the studies conducted, a magnetic configuration with a large n = 1 , m = 3 magnetic island at the edge is generated. Results from multiple potential divertor plate locations will be presented and discussed. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  8. Active control of divertor asymmetry on EAST by localized D2 and Ar puffing

    NASA Astrophysics Data System (ADS)

    Wang, Dongsheng; Guo, Houyang; Wang, Huiqian; Luo, Guangnan; Wu, Zhenwei; Wu, Jinhua; Gao, Wei; Wang, Liang; Li, Qiang; East Team

    2011-03-01

    The divertor asymmetry in particle and power fluxes has been investigated on the EAST superconducting tokamak [S. Wu and EAST Team, Fusion Eng. Des. 82, 463 (2007)] for both single null (SN) and double null (DN) divertor configurations. D2 and Ar puffing at various divertor locations has also been explored as an active means to reduce peak target heat load and control divertor asymmetry. For SN, peak heat load on the outer divertor target is 2-3 times that on the inner divertor target under typical ohmic plasma conditions. DN operation leads to a stronger in-out asymmetry favoring the outer divertor. D2 and Ar puffing promotes partial detachment near the strike points, greatly reducing peak target heat load (over 50%), while the far-SOL divertor plasma remains attached. What is remarkable is that the particle flux is even increased away from the strike points when the B×∇B drift is directed toward the divertor target, thus facilitating particle removal.

  9. The effect of the magnetic topology on particle recycling in the ergodic divertor of TEXTOR

    NASA Astrophysics Data System (ADS)

    Lehnen, M.; Abdullaev, S. S.; Brezinsek, S.; Finken, K. H.; Harting, D.; von Hellermann, M.; Jakubowski, M. W.; Jaspers, R.; Kirschner, A.; Pospieszczyk, A.; Reiter, D.; Samm, U.; Schmitz, O.; Sergienko, G.; Unterberg, B.; Wolf, R.; Textor Team

    2007-06-01

    The influence of the divertor geometry of the dynamic ergodic divertor (DED) in TEXTOR on particle recycling is discussed. The geometry can be varied by the choice of the base mode, the edge safety factor and the divertor coil current. The divertor volume is split into the upstream and the downstream area. Strong plasma flows in the downstream area, essential for high screening efficiency, are predicted. The source strength of deuterium and carbon in the downstream area is estimated by using the two-dimensional distribution of Dα and CIII emission in front of the target. The results are compared to EMC3 and ERO-code calculations.

  10. Divertor plasma conditions and neutral dynamics in horizontal and vertical divertor configurations in JET-ILW low confinement mode plasmas

    NASA Astrophysics Data System (ADS)

    Groth, M.; Brezinsek, S.; Belo, P.; Brix, M.; Calabro, G.; Chankin, A.; Clever, M.; Coenen, J. W.; Corrigan, G.; Drewelow, P.; Guillemaut, C.; Harting, D.; Huber, A.; Jachmich, S.; Järvinen, A.; Kruezi, U.; Lawson, K. D.; Lehnen, M.; Maggi, C. F.; Marchetto, C.; Marsen, S.; Maviglia, F.; Meigs, A. G.; Moulton, D.; Silva, C.; Stamp, M. F.; Wiesen, S.

    2015-08-01

    Measurements of the plasma conditions at the low field side target plate in JET ITER-like wall ohmic and low confinement mode plasmas show minor differences in divertor plasma configurations with horizontally and vertically inclined targets. Both the reduction of the electron temperature in the vicinity of the strike points and the rollover of the ion current to the plates follow the same functional dependence on the density at the low field side midplane. Configurations with vertically inclined target plates, however, produce twice as high sub-divertor pressures for the same upstream density. Simulations with the EDGE2D-EIRENE code package predict significantly lower plasma temperatures at the low field side target in vertical than in horizontal target configurations. Including cross-field drifts and imposing a pumping by-pass leak at the low-field side plate can still not recover the experimental observations.

  11. Investigations on the heat flux and impurity for the HL-2M divertor

    NASA Astrophysics Data System (ADS)

    Zheng, G. Y.; Cai, L. Z.; Duan, X. R.; Xu, X. Q.; Ryutov, D. D.; Cai, L. J.; Liu, X.; Li, J. X.; Pan, Y. D.

    2016-12-01

    The controllability of the heat load and impurity in the divertor is very important, which could be one of the critical problems to be solved in order to ensure the success for a steady state tokamak. HL-2M has the advantage of the poloidal field (PF) coils placed inside the demountable toroidal field (TF) coils and close to the main plasma. As a result, it is possible to make highly accurate configuration control of the advanced divertor for HL-2M. The divertor target geometry of HL-2M has been designed to be compatible with different divertor configurations to study the divertor physics and support the high performance plasma operations. In this paper, the heat loads and impurities with different divertor configurations, including the standard X-point divertor, the snowflake-minus divertor and two tripod divertor configurations for HL-2M, are investigated by numerical simulations with the SOLPS5.0 code under the current design of the HL-2M divertor geometry. The plasmas with different conditions, such as the low discharge parameters with {{I}\\text{p}}   =  0.5 MA at the first stage of HL-2M and the high parameters with {{I}\\text{p}}   =  2.0 MA during the normal operations, are simulated. The heat load profiles and the impurity distributions are obtained, and the control of the peak heat load and the effect of impurity on the core plasma are discussed. The compatibility of different divertor configurations for HL-2M is also evaluated. It is seen that the excellent compatibility of different divertor configurations with the current divertor geometry has been verified. The results show that the snowflake-minus divertor and the tripod divertor with {{d}x}=30 \\text{cm} present good performance in terms of the heat load profiles and the impurity distributions under different conditions, which may not have a big effect on the core plasma. In addition, it is possible to optimize the distance between the two X-points, {{d}x} , to achieve a better

  12. Current status of ultrasonography of the finger

    PubMed Central

    2016-01-01

    The recent development of advanced high-resolution transducers has enabled the fast, easy, and dynamic ultrasonographic evaluation of small, superficial structures such as the finger. In order to best exploit these advances, it is important to understand the normal anatomy and the basic pathologies of the finger, as exemplified by the following conditions involving the dorsal, volar, and lateral sections of the finger: sagittal band injuries, mallet finger, and Boutonnière deformity (dorsal aspect); flexor tendon tears, trigger finger, and volar plate injuries (volar aspect); gamekeeper’s thumb (Stener lesions) and other collateral ligament tears (lateral aspect); and other lesions. This review provides a basis for understanding the ultrasonography of the finger and will therefore be useful for radiologists. PMID:26753604

  13. Piezoelectric Actuators On A Cold Finger

    NASA Technical Reports Server (NTRS)

    Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

    1995-01-01

    Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

  14. Study on Axially Distributed Divertor Magnetic Field Configuration in a Mirror Cell

    SciTech Connect

    Islam, M.K.; Nakashima, Y.; Higashizono, Y.; Katanuma, I.; Cho, T

    2005-01-15

    A mirror magnetic field configuration (MFC) is studied in which a divertor is distributed axially using multipole coils. Both configurations of divertor and minimum-B are obtained in a mirror cell. Magnetohydrodynamic (MHD) instability of a mirror cell can be eliminated in this way. Concept of the design and properties of the MFC are discussed.

  15. Investigation of scrape-off layer and divertor heat transport in ASDEX Upgrade L-mode

    NASA Astrophysics Data System (ADS)

    Sieglin, B.; Eich, T.; Faitsch, M.; Herrmann, A.; Scarabosio, A.; the ASDEX Upgrade Team

    2016-05-01

    Power exhaust is one of the major challenges for the development of a fusion power plant. Predictions based upon a multimachine database give a scrape-off layer power fall-off length {λq}≤slant 1 mm for large fusion devices such as ITER. The power deposition profile on the target is broadened in the divertor by heat transport perpendicular to the magnetic field lines. This profile broadening is described by the power spreading S. Hence both {λq} and S need to be understood in order to estimate the expected divertor heat load for future fusion devices. For the investigation of S and {λq} L-Mode discharges with stable divertor conditions in hydrogen and deuterium were conducted in ASDEX Upgrade. A strong dependence of S on the divertor electron temperature and density is found which is the result of the competition between parallel electron heat conductivity and perpendicular diffusion in the divertor region. For high divertor temperatures it is found that the ion gyro radius at the divertor target needs to be considered. The dependence of the in/out asymmetry of the divertor power load on the electron density is investigated. The influence of the main ion species on the asymmetric behaviour is shown for hydrogen, deuterium and helium. A possible explanation for the observed asymmetry behaviour based on vertical drifts is proposed.

  16. Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamaka)

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; McLean, A. G.; Allen, S. L.

    2014-11-01

    New near infrared (NIR) spectroscopic measurements performed in the DIII-D tokamak divertor plasma suggest new viable diagnostic applications: divertor recycling and low-Z impurity flux measurements, a spectral survey for divertor Thomson scattering (DTS) diagnostic, and Te monitoring for divertor detachment control. A commercial 0.3 m spectrometer coupled to an imaging lens via optical fiber and a InGaAs 1024 pixel array detector enabled deuterium and impurity emission measurements in the range 800-2300 nm. The first full NIR survey identified D, He, B, Li, C, N, O, Ne lines and provided plasma Te, ne estimates from deuterium Paschen and Brackett series intensity and Stark line broadening analysis. The range 1.000-1.060 mm was surveyed in high-density and neon seeded divertor plasmas for spectral background emission studies for λ = 1.064 μm laser-based DTS development. The ratio of adjacent deuterium Paschen-α and Brackett Br9 lines in recombining divertor plasmas is studied for divertor Te monitoring aimed at divertor detachment real-time feedback control.

  17. Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamak

    SciTech Connect

    Soukhanovskii, V. A. McLean, A. G.; Allen, S. L.

    2014-11-15

    New near infrared (NIR) spectroscopic measurements performed in the DIII-D tokamak divertor plasma suggest new viable diagnostic applications: divertor recycling and low-Z impurity flux measurements, a spectral survey for divertor Thomson scattering (DTS) diagnostic, and T{sub e} monitoring for divertor detachment control. A commercial 0.3 m spectrometer coupled to an imaging lens via optical fiber and a InGaAs 1024 pixel array detector enabled deuterium and impurity emission measurements in the range 800–2300 nm. The first full NIR survey identified D, He, B, Li, C, N, O, Ne lines and provided plasma T{sub e}, n{sub e} estimates from deuterium Paschen and Brackett series intensity and Stark line broadening analysis. The range 1.000–1.060 mm was surveyed in high-density and neon seeded divertor plasmas for spectral background emission studies for λ = 1.064 μm laser-based DTS development. The ratio of adjacent deuterium Paschen-α and Brackett Br9 lines in recombining divertor plasmas is studied for divertor T{sub e} monitoring aimed at divertor detachment real-time feedback control.

  18. Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamak.

    PubMed

    Soukhanovskii, V A; McLean, A G; Allen, S L

    2014-11-01

    New near infrared (NIR) spectroscopic measurements performed in the DIII-D tokamak divertor plasma suggest new viable diagnostic applications: divertor recycling and low-Z impurity flux measurements, a spectral survey for divertor Thomson scattering (DTS) diagnostic, and Te monitoring for divertor detachment control. A commercial 0.3 m spectrometer coupled to an imaging lens via optical fiber and a InGaAs 1024 pixel array detector enabled deuterium and impurity emission measurements in the range 800-2300 nm. The first full NIR survey identified D, He, B, Li, C, N, O, Ne lines and provided plasma Te, ne estimates from deuterium Paschen and Brackett series intensity and Stark line broadening analysis. The range 1.000-1.060 mm was surveyed in high-density and neon seeded divertor plasmas for spectral background emission studies for λ = 1.064 μm laser-based DTS development. The ratio of adjacent deuterium Paschen-α and Brackett Br9 lines in recombining divertor plasmas is studied for divertor Te monitoring aimed at divertor detachment real-time feedback control. PMID:25430325

  19. Near-infrared spectroscopy for divertor plasma diagnosis and control in DIII-D tokamak.

    PubMed

    Soukhanovskii, V A; McLean, A G; Allen, S L

    2014-11-01

    New near infrared (NIR) spectroscopic measurements performed in the DIII-D tokamak divertor plasma suggest new viable diagnostic applications: divertor recycling and low-Z impurity flux measurements, a spectral survey for divertor Thomson scattering (DTS) diagnostic, and Te monitoring for divertor detachment control. A commercial 0.3 m spectrometer coupled to an imaging lens via optical fiber and a InGaAs 1024 pixel array detector enabled deuterium and impurity emission measurements in the range 800-2300 nm. The first full NIR survey identified D, He, B, Li, C, N, O, Ne lines and provided plasma Te, ne estimates from deuterium Paschen and Brackett series intensity and Stark line broadening analysis. The range 1.000-1.060 mm was surveyed in high-density and neon seeded divertor plasmas for spectral background emission studies for λ = 1.064 μm laser-based DTS development. The ratio of adjacent deuterium Paschen-α and Brackett Br9 lines in recombining divertor plasmas is studied for divertor Te monitoring aimed at divertor detachment real-time feedback control.

  20. Magnetic turbulence and resistive MHD instabilities in a 0. 6 < q < 3 poloidal divertor tokamak

    SciTech Connect

    Agim, Y.Z.; Callen, J.D.; Chang, Z.; Dexter, R.N.; Goetz, J.A.; Graessle, D.E.; Haines, E.; Kortbawi, D.; LaPointe, M.A.; Moyer, R.A.

    1988-09-01

    Detailed statistical properties of internal magnetic turbulence, and internal disruptions in magnetically- and materially-limited discharges, are studied in the Tokapole II poloidal divertor tokamak over the safety factor range 0.6 < q{sub a} < 3. A nonlinear MHD code treats tearing modes in the divertor geometry. 9 refs., 2 figs.

  1. Trigger Finger: Adult and Pediatric Treatment Strategies.

    PubMed

    Giugale, Juan M; Fowler, John R

    2015-10-01

    Trigger fingers are common tendinopathies representing a stenosing flexor tenosynovitis of the fingers. Adult trigger finger can be treated nonsurgically using activity modification, splinting, and/or corticosteroid injections. Surgical treatment options include percutaneous A1 pulley release and open A1 pulley release. Excision of a slip of the flexor digitorum superficialis is reserved for patients with persistent triggering despite A1 release or patients with persistent flexion contracture. Pediatric trigger thumb is treated with open A1 pulley release. Pediatric trigger finger is treated with release of the A1 pulley with excision of a slip or all of the flexor digitorum superficialis if triggering persists. PMID:26410644

  2. Reconstruction of Detached Divertor Plasma Conditions in DIII-D Using Spectroscopic and Probe Data

    SciTech Connect

    Stangeby, P; Fenstermacher, M

    2004-12-03

    For some divertor aspects, such as detached plasmas or the private flux zone, it is not clear that the controlling physics has been fully identified. This is a particular concern when the details of the plasma are likely to be important in modeling the problem--for example, modeling co-deposition in detached inner divertors. An empirical method of ''reconstructing'' the plasma based on direct experimental measurements may be useful in such situations. It is shown that a detached plasma in the outer divertor leg of DIII-D can be reconstructed reasonably well using spectroscopic and probe data as input to a simple onion-skin model and the Monte Carlo hydrogenic code, EIRENE. The calculated 2D distributions of n{sub e} and T{sub e} in the detached divertor were compared with direct measurements from the divertor Thomson scattering system, a diagnostic capability unique to DIII-D.

  3. Facilities for technology testing of ITER divertor concepts, models, and prototypes in a plasma environment

    SciTech Connect

    Cohen, S.A.

    1991-12-01

    The exhaust of power and fusion-reaction products from ITER plasma are critical physics and technology issues from performance, safety, and reliability perspectives. Because of inadequate pulse length, fluence, flux, scrape-off layer plasma temperature and density, and other parameters, the present generation of tokamaks, linear plasma devices, or energetic beam facilities are unable to perform adequate technology testing of divertor components, though they are essential contributors to many physics issues such as edge-plasma transport and disruption effects and control. This Technical Requirements Documents presents a description of the capabilities and parameters divertor test facilities should have to perform accelerated life testing on predominantly technological divertor issues such as basic divertor concepts, heat load limits, thermal fatigue, tritium inventory and erosion/redeposition. The cost effectiveness of such divertor technology testing is also discussed.

  4. The dynamical mechanical properties of tungsten under compression at working temperature range of divertors

    NASA Astrophysics Data System (ADS)

    Zhu, C. C.; Song, Y. T.; Peng, X. B.; Wei, Y. P.; Mao, X.; Li, W. X.; Qian, X. Y.

    2016-02-01

    In the divertor structure of ITER and EAST with mono-block module, tungsten plays not only a role of armor material but also a role of structural material, because electromagnetic (EM) impact will be exerted on tungsten components in VDEs or CQ. The EM loads can reach to 100 MN, which would cause high strain rates. In addition, directly exposed to high-temperature plasma, the temperature regime of divertor components is complex. Aiming at studying dynamical response of tungsten divertors under EM loads, an experiment on tungsten employed in EAST divertors was performed using a Kolsky bar system. The testing strain rates and temperatures is derived from actual working conditions, which makes the constitutive equation concluded by using John-Cook model and testing data very accurate and practical. The work would give a guidance to estimate the dynamical response, fatigue life and damage evolution of tungsten divertor components under EM impact loads.

  5. Performance characteristics of the DIII-D advanced divertor cryopump

    SciTech Connect

    Menon, M.M.; Maingi, R.; Wade, M.R.; Baxi, C.B.; Campbell, G.L.; Holtrop, K.L.; Hyatt, A.W.; Laughon, G.J.; Makariou, C.C.; Mahdavi, M.A.; Reis, E.E.; Schaffer, M.J.; Schaubel, K.M.; Scoville, J.T.; Smith, J.P.; Stambaugh, R.D.

    1993-10-01

    A cryocondensation pump, cooled by forced flow of two-phase helium, has been installed for particle exhaust from the divertor region of the DIII-D tokamak. The Inconel pumping surface is of coaxial geometry, 25.4 mm in outer diameter and 11.65 m in length. Because of the tokamak environment, the pump is designed to perform under relatively high pulsed heat loads (300 Wm{sup {minus}2}). Results of measurements made on the pumping characteristics for D{sub 2}, H{sub 2}, and Ar are discussed.

  6. Ballooning Modes in the Systems Stabilized by Divertors

    SciTech Connect

    Arsenin, V.V.; Skovoroda, A.A.; Zvonkov, A.V.

    2005-01-15

    MHD stability of a plasma in systems with closed magnetic field lines and open systems containing the nonparaxial stabilizing cells with large field lines curvature, in particular, divertors is analyzed. It is shown that population of particles trapped in such cells has a stabilizing effect not only on flute modes, but also on ballooning modes that determine the {beta} limit. At kinetic description that accounts for different effect of trapped and passing particles on perturbations, {beta} limit permitted by stability may be much greater then it follows from MHD model.

  7. Crossed-field divertor for a plasma device

    DOEpatents

    Kerst, Donald W.; Strait, Edward J.

    1981-01-01

    A divertor for removal of unwanted materials from the interior of a magnetic plasma confinement device includes the division of the wall of the device into segments insulated from each other in order to apply an electric field having a component perpendicular to the confining magnetic field. The resulting crossed-field drift causes electrically charged particles to be removed from the outer part of the confinement chamber to a pumping chamber. This method moves the particles quickly past the saddle point in the poloidal magnetic field where they would otherwise tend to stall, and provides external control over the rate of removal by controlling the magnitude of the electric field.

  8. JET divertor diagnostic upgrade for neutral gas analysis.

    PubMed

    Kruezi, Uron; Sergienko, G; Morgan, P D; Matthews, G F; Brezinsek, S; Vartanian, S

    2012-10-01

    With installation of the ITER-like wall in JET a major diagnostic upgrade to measure the neutral gas pressure and composition in the sub-divertor region has been completed, to characterise retention and outgassing of the new metallic first wall. The upgrade includes two new magnetically shielded systems consisting of sensitive capacitance manometers and residual gas analysers, both capable of providing data during plasma operation. These enable absolute pressure and gas composition measurements (pressure range: 10(-5)-10(-1) mbar, mass range: 1-200 amu, respectively) and have been used to characterise the neutral gas behaviour under various plasma conditions.

  9. Creating Number Semantics through Finger Movement Perception

    ERIC Educational Resources Information Center

    Badets, Arnaud; Pesenti, Mauro

    2010-01-01

    Communication, language and conceptual knowledge related to concrete objects may rely on the sensory-motor systems from which they emerge. How abstract concepts can emerge from these systems is however still unknown. Here we report a functional interaction between a specific meaningful finger movement, such as a finger grip closing, and a concept…

  10. Simultaneous double interphalangeal dislocation in one finger.

    PubMed

    Takami, H; Takahashi, S; Ando, M

    2000-01-01

    Isolated dislocation of the proximal or distal interphalangeal joint of a finger is common, but simultaneous dislocation of both joints is rare. Three cases of simultaneous dislocations of both interphalangeal joints in the same finger are reported. Closed reduction was easily achieved in all cases.

  11. Power deposition in the JET divertor during ELMs

    NASA Astrophysics Data System (ADS)

    Clement, S.; Chankin, A.; Ciric, D.; Coad, J. P.; Falter, J.; Gauthier, E.; Lingertat, J.; Puppin, S.

    The power deposited in the JET divertor during ELMs has been evaluated using an infrared camera specifically designed for fast measurements. The first results [E. Gauthier, A. Charkin, S. Clement et al., Proc. 24th Euro. conf. on contr. Fusion and Plasma Phys., Berchtesgaden, 1997 (European Physical Society, 1998), vol. 21A, p. 61.] indicated that during type I ELMs, surface temperatures in excess of 2000°C were measured, leading to peak power fluxes in the order of 4 GW/m 2. The time integrated power flux exceeded the measured plasma energy loss per ELM by a factor of four. The reasons for this discrepancy are studied in this paper. Redeposited carbon layers of up to 40 μm have been found on the divertor surface in the places where the highest temperatures are measured. The impact of such layers on the power flux evaluation has been studied with numerical calculations, and a controlled simulation of ELM heating has been performed in the JET neutral beam test facility. It is found that neglecting the existence of layers on the surface in a 2D calculation can lead to overestimating the power by a factor of 3, whereas the error in the calculation of the energy is much smaller. An energy based calculation reduces the peak power during type I ELMs to values around 1.2 GW/m 2.

  12. Ion Temperature Measurements in the DIII--D Divertor

    NASA Astrophysics Data System (ADS)

    Brooks, N. H.; Isler, R. C.; McKee, G. R.; Tugarinov, S.

    1996-11-01

    Doppler profile measurements of the D_α, He II, C II and C III line emission in the DIII--D divertor have been performed with two high resolution spectrometers: an instrument of Russian design with high optical throughput and 7 ms readout, and a conventional Czerny Turner spectrometer with slower response time, but greater dynamic range in its detector system. In continuous ELMing H--mode plasmas the Doppler profiles are usually single-gaussian, but during operation at low density or during large, discrete ELM events the profiles of the hydrogen-like species are often multi-gaussian. Comparison of ion temperatures inferred from the single-gaussian profiles and electron temperatures measured by Thomson scattering and by spectroscopic line ratio methods yields good agreement for the higher charge states, where equilibration of ion and electron temperatures is expected. When strong D2 puffing triggers the MARFE-like conditions of Partially Detached Divertor plasmas, the D_α line profile, usually a complex asymmetric profile with multiple components, evolves into a single-gaussian profile fitted by a very low temperature (<2 eV) similar to that measured for the electrons by Thomson scattering.

  13. Ballooning modes localized near the null point of a divertor

    SciTech Connect

    Farmer, W. A.

    2014-04-15

    The stability of ballooning modes localized to the null point in both the standard and snowflake divertors is considered. Ideal magnetohydrodynamics is used. A series expansion of the flux function is performed in the vicinity of the null point with the lowest, non-vanishing term retained for each divertor configuration. The energy principle is used with a trial function to determine a sufficient instability threshold. It is shown that this threshold depends on the orientation of the flux surfaces with respect to the major radius with a critical angle appearing due to the convergence of the field lines away from the null point. When the angle the major radius forms with respect to the flux surfaces exceeds this critical angle, the system is stabilized. Further, the scaling of the instability threshold with the aspect ratio and the ratio of the scrape-off-layer width to the major radius is shown. It is concluded that ballooning modes are not a likely candidate for driving convection in the vicinity of the null for parameters relevant to existing machines. However, the results place a lower bound on the width of the heat flux in the private flux region. To explain convective mixing in the vicinity of the null point, new consideration should be given to an axisymmetric mixing mode [W. A. Farmer and D. D. Ryutov, Phys. Plasmas 20, 092117 (2013)] as a possible candidate to explain current experimental results.

  14. First EMC3-Eirene simulations of the TCV snowflake divertor

    NASA Astrophysics Data System (ADS)

    Lunt, T.; Canal, G. P.; Feng, Y.; Reimerdes, H.; Duval, B. P.; Labit, B.; Vijvers, W. A. J.; Coster, D.; Lackner, K.; Wischmeier, M.

    2014-03-01

    One of the approaches to solve the heat load problem in a divertor tokamak is the so called ‘snowflake’ (SF) configuration, a magnetic equilibrium with two nearby x-points and two additional divertor legs. Here we report on the first EMC3-Eirene simulations of plasma- and neutral particle transport in the scrape-off layer of a series of TCV SF equilibria with different values of σ, the distance between the x-points normalized to the minor radius of the plasma. The constant cross-field transport coefficients were chosen such that the power- and particle deposition profiles at the primary inner strike point (SP) match the Langmuir probe measurements for the σ = 0.1 case. At the secondary SP on the floor, however, a significantly larger power flux than that predicted by the simulation was measured by the probes, indicating an enhanced transport across the primary separatrix. As the ideal SF configuration (σ = 0) is approached, the density as well as the radiation maximum are predicted to move from the target plates upward to the x-point by the simulation.

  15. Towards a Lithium Radiative / Vapor-Box Divertor

    NASA Astrophysics Data System (ADS)

    Goldston, Robert; Constantin, Marius; Jaworski, Michael; Myers, Rachel; Ono, Masayuki; Schwartz, Jacob; Scotti, Filippo; Qu, Zhaonan

    2014-10-01

    Recent research has indicated that the peak perpendicular heat flux on reactor divertor targets will be hundreds of MW/m2 in the absence of dissipation and/or spatial spreading. Thus we are attracted to both enhanced radiative cooling and continuous vapor shielding. Lithium particle lifetimes <=100 micro-sec enhance radiation efficiency at T < 10 eV, while lithium charge-exchange with neutral hydrogen may enhance radiative efficiency for T > 10 eV and n0/ni > 0.1. We are examining if the latter mechanism plays a role in the narrowing of the heat-flux footprint in lithiated NSTX discharges. In parallel we are investigating the possibility of immersing a reactor divertor leg in a channel of lithium vapor. If we approximate the vapor channel as in local equilibrium with lithium-wetted walls ranging from 300 oC at the entrance point to 950 oC 10m downstream in the parallel direction, we find that the vapor can both balance reactor levels of upstream plasma pressure and stop energetic ions and electrons with energies up to at least 25 keV, as might be produced in ELMs. Each 10 l/sec of lithium evaporated deep in the channel and recondensed in cooler regions spreads 100 MW over a much wider area than the original strike point. This work supported by US DOE Contract DE-AC02-09CH11466.

  16. Axisymmetric curvature-driven instability in a model divertor geometry

    SciTech Connect

    Farmer, W. A.; Ryutov, D. D.

    2013-09-15

    A model problem is presented which qualitatively describes a pressure-driven instability which can occur near the null-point in the divertor region of a tokamak where the poloidal field becomes small. The model problem is described by a horizontal slot with a vertical magnetic field which plays the role of the poloidal field. Line-tying boundary conditions are applied at the planes defining the slot. A toroidal field lying parallel to the planes is assumed to be very strong, thereby constraining the possible structure of the perturbations. Axisymmetric perturbations which leave the toroidal field unperturbed are analyzed. Ideal magnetohydrodynamics is used, and the instability threshold is determined by the energy principle. Because of the boundary conditions, the Euler equation is, in general, non-separable except at marginal stability. This problem may be useful in understanding the source of heat transport into the private flux region in a snowflake divertor which possesses a large region of small poloidal field, and for code benchmarking as it yields simple analytic results in an interesting geometry.

  17. Asthenospheric Mantle Flow by Viscous Fingering Instabilities

    NASA Astrophysics Data System (ADS)

    Weeraratne, D. S.; Parmentier, E.

    2010-12-01

    We investigate mantle flow in the oceanic asthenospheric by lateral flow of viscous fingering instabilities. In this model, the asthenosphere acts as a channel for mantle flow from an off axis source to the spreading center, perhaps on a global scale. This phenomenon may be observed by linear chains of intraplate volcanism on young seafloor near ridge axes where we suggest asthenospheric fingering material may induce melting beneath thin lithosphere. We perform laboratory fluid experiments of viscous fingering in miscible high viscosity fluids which flow radially through a Hele-Shaw cell. Fluids with low Reynolds number provide scaling to the Earth's mantle where viscous forces dominate and chemical diffusion is slow. We find that viscous fingers are well developed in this geodynamic regime with the fingering wavelength (λ f) controlled by viscous dissipation in the displaced fluid. Fingering patterns approach a constant wavelength after an initial growth phase and depend on plate spacing (B) as {λ f} = 12B. We also observe the formation of a film layer surrounding low viscosity fingers as they propagate. When density differences exist between the two fluids, the film layer above the finger is higher density, inherently unstable, and begins to downwell as a Rayleigh-Taylor instabilities observed in shadowgraphs as white striations within each finger that are linear and regularly spaced. We find the wavelength of striations ({λ st}) scales with finger growth as {λ st}= 4 {λ f}. The application of a moving surface plate is observed to align all fingers in a linear direction parallel to plate motion both downstream and upstream. These experiments suggest that mantle flow in the Earth's asthenosphere may be exhibit instabilities governed by viscous fingering if sufficient viscosity variations are present between the depleted asthenosphere and the introduction of low viscosity, volatile rich, off-axis plume material. This viscous fingering model predicts a

  18. An exploration of advanced X-divertor scenarios on ITER

    NASA Astrophysics Data System (ADS)

    Covele, B.; Valanju, P.; Kotschenreuther, M.; Mahajan, S.

    2014-07-01

    It is found that the X-divertor (XD) configuration (Kotschenreuther et al 2004 Proc. 20th Int. Conf. on Fusion Energy (Vilamoura, Portugal, 2004) (Vienna: IAEA) CD-ROM file [IC/P6-43] www-naweb.iaea.org/napc/physics/fec/fec2004/datasets/index.html, Kotschenreuther et al 2006 Proc. 21st Int. Conf. on Fusion Energy 2006 (Chengdu, China, 2006) (Vienna: IAEA), CD-ROM file [IC/P7-12] www-naweb.iaea.org/napc/physics/FEC/FEC2006/html/index.htm, Kotschenreuther et al 2007 Phys. Plasmas 14 072502) can be made with the conventional poloidal field (PF) coil set on ITER (Tomabechi et al and Team 1991 Nucl. Fusion 31 1135), where all PF coils are outside the TF coils. Starting from the standard divertor, a sequence of desirable XD configurations are possible where the PF currents are below the present maximum design limits on ITER, and where the baseline divertor cassette is used. This opens the possibility that the XD could be tested and used to assist in high-power operation on ITER, but some further issues need examination. Note that the increased major radius of the super-X-divertor (Kotschenreuther et al 2007 Bull. Am. Phys. Soc. 53 11, Valanju et al 2009 Phys. Plasmas 16 5, Kotschenreuther et al 2010 Nucl. Fusion 50 035003, Valanju et al 2010 Fusion Eng. Des. 85 46) is not a feature of the XD geometry. In addition, we present an XD configuration for K-DEMO (Kim et al 2013 Fusion Eng. Des. 88 123) to demonstrate that it is also possible to attain the XD configuration in advanced tokamak reactors with all PF coils outside the TF coils. The results given here for the XD are far more encouraging than recent calculations by Lackner and Zohm (2012 Fusion Sci. Technol. 63 43) for the Snowflake (Ryutov 2007 Phys. Plasmas 14 064502, Ryutov et al 2008 Phys. Plasmas 15 092501), where the required high PF currents represent a major technological challenge. The magnetic field structure in the outboard divertor SOL (Kotschenreuther 2013 Phys. Plasmas 20 102507) in the recently created

  19. Fingering in Stochastic Growth Models

    PubMed Central

    Aristotelous, Andreas C.; Durrett, Richard

    2015-01-01

    Motivated by the widespread use of hybrid-discrete cellular automata in modeling cancer, two simple growth models are studied on the two dimensional lattice that incorporate a nutrient, assumed to be oxygen. In the first model the oxygen concentration u(x, t) is computed based on the geometry of the growing blob, while in the second one u(x, t) satisfies a reaction-diffusion equation. A threshold θ value exists such that cells give birth at rate β(u(x, t) − θ)+ and die at rate δ(θ − u(x, t)+. In the first model, a phase transition was found between growth as a solid blob and “fingering” at a threshold θc = 0.5, while in the second case fingering always occurs, i.e., θc = 0. PMID:26430353

  20. Differing Dynamics of Intrapersonal and Interpersonal Coordination: Two-finger and Four-Finger Tapping Experiments

    PubMed Central

    Kodama, Kentaro; Furuyama, Nobuhiro; Inamura, Tetsunari

    2015-01-01

    Finger-tapping experiments were conducted to examine whether the dynamics of intrapersonal and interpersonal coordination systems can be described equally by the Haken—Kelso—Bunz model, which describes inter-limb coordination dynamics. This article reports the results of finger-tapping experiments conducted in both systems. Two within-subject factors were investigated: the phase mode and the number of fingers. In the intrapersonal experiment (Experiment 1), the participants were asked to tap, paced by a gradually hastening auditory metronome, looking at their fingers moving, using the index finger in the two finger condition, or the index and middle finger in the four-finger condition. In the interpersonal experiment (Experiment 2), pairs of participants performed the task while each participant used the outside hand, tapping with the index finger in the two finger condition, or the index and middle finger in the four-finger condition. Some results did not agree with the HKB model predictions. First, from Experiment 1, no significant difference was observed in the movement stability between the in-phase and anti-phase modes in the two finger condition. Second, from Experiment 2, no significant difference was found in the movement stability between the in-phase and anti-phase mode in the four-finger condition. From these findings, different coordination dynamics were inferred between intrapersonal and interpersonal coordination systems against prediction from the previous studies. Results were discussed according to differences between intrapersonal and interpersonal coordination systems in the availability of perceptual information and the complexity in the interaction between limbs derived from a nested structure. PMID:26070119

  1. Simulation of tokamak SOL and divertor region including heat flux mitigation by gas puffing

    SciTech Connect

    Park, Jin Woo; Na, Y. S.; Hong, S. H.; Ahn, J.W.; Kim, D. K.; Han, Hyunsun; Shim, Seong Bo; Lee, Hae June

    2012-01-01

    Two-dimensional (2D), scrape-off layer (SOL)-divertor transport simulations are performed using the integrated plasma-neutral-impurity code KTRAN developed at Seoul National University. Firstly, the code is applied to reproduce a National Spherical Torus eXperiment (NSTX) discharge by using the prescribed transport coefficients and the boundary conditions obtained from the experiment. The plasma density, the heat flux on the divertor plate, and the D (alpha) emission rate profiles from the numerical simulation are found to follow experimental trends qualitatively. Secondly, predictive simulations are carried out for the baseline operation mode in Korea Superconducting Tokamak Advanced Research (KSTAR) to predict the heat flux on the divertor target plates. The stationary peak heat flux in the KSTAR baseline operation mode is expected to be 6.5 MW/m(2) in the case of an orthogonal divertor. To study the mitigation of the heat flux, we investigated the puffing effects of deuterium and argon gases. The puffing position is assumed to be in front of the strike point at the outer lower divertor plate. In the simulations, mitigation of the peak heat flux at the divertor target plates is found to occur when the gas puffing rate exceeds certain values, similar to 1.0 x 10(20) /s and similar to 5.0 x 10(18) /s for deuterium and argon, respectively. Multi-charged impurity transport is also investigated for both NSTX and KSTAR SOL and divertor regions.

  2. Heat loads to divertor nearby components from secondary radiation evolved during plasma instabilities

    SciTech Connect

    Sizyuk, V. Hassanein, A.

    2015-01-15

    A fundamental issue in tokamak operation related to power exhaust during plasma instabilities is the understanding of heat and particle transport from the core plasma into the scrape-off layer and to plasma-facing materials. During abnormal and disruptive operation in tokamaks, radiation transport processes play a critical role in divertor/edge-generated plasma dynamics and are very important in determining overall lifetimes of the divertor and nearby components. This is equivalent to or greater than the effect of the direct impact of escaped core plasma on the divertor plate. We have developed and implemented comprehensive enhanced physical and numerical models in the upgraded HEIGHTS package for simulating detailed photon and particle transport in the evolved edge plasma during various instabilities. The paper describes details of a newly developed 3D Monte Carlo radiation transport model, including optimization methods of generated plasma opacities in the full range of expected photon spectra. Response of the ITER divertor's nearby surfaces due to radiation from the divertor-developed plasma was simulated by using actual full 3D reactor design and magnetic configurations. We analyzed in detail the radiation emission spectra and compared the emission of both carbon and tungsten as divertor plate materials. The integrated 3D simulation predicted unexpectedly high damage risk to the open stainless steel legs of the dome structure in the current ITER design from the intense radiation during a disruption on the tungsten divertor plate.

  3. Simulation of tokamak SOL and divertor region including heat flux mitigation by gas puffing

    NASA Astrophysics Data System (ADS)

    Park, Jin-Woo; Na, Yong-Su; Hong, Sang Hee; Ahn, Joon-Wook; Kim, Deok-Kyu; Han, Hyunsun; Shim, Seong Bo; Lee, Hae June

    2012-08-01

    Two-dimensional (2D), scrape-off layer (SOL)-divertor transport simulations are performed using the integrated plasma-neutral-impurity code KTRAN developed at Seoul National University. Firstly, the code is applied to reproduce a National Spherical Torus eXperiment (NSTX) discharge by using the prescribed transport coefficients and the boundary conditions obtained from the experiment. The plasma density, the heat flux on the divertor plate, and the D α emission rate profiles from the numerical simulation are found to follow experimental trends qualitatively. Secondly, predictive simulations are carried out for the baseline operation mode in Korea Superconducting Tokamak Advanced Research (KSTAR) to predict the heat flux on the divertor target plates. The stationary peak heat flux in the KSTAR baseline operation mode is expected to be 6.5 MW/m2 in the case of an orthogonal divertor. To study the mitigation of the heat flux, we investigated the puffing effects of deuterium and argon gases. The puffing position is assumed to be in front of the strike point at the outer lower divertor plate. In the simulations, mitigation of the peak heat flux at the divertor target plates is found to occur when the gas puffing rate exceeds certain values, ˜1.0 × 1020 /s and ˜5.0 × 1018 /s for deuterium and argon, respectively. Multi-charged impurity transport is also investigated for both NSTX and KSTAR SOL and divertor regions.

  4. Probe measurements of the PDX divertor plasma in ohmic and neutral beam heated discharges

    NASA Astrophysics Data System (ADS)

    Owens, D. K.; Kaye, S. M.; Fonck, R. J.; Schmidt, G. L.

    1984-05-01

    A graphite-shielded probe was recently installed in the divertor region of PDX to continuously monitor local electron temperature, electron density (from the ion saturation current), and plasma floating potential throughout divertor discharges. In ohmically heated deuterium plasmas, the electron temperature near the separatrix was 6 to 12 eV; these values confirm the low Te inferred from the density dependence of Balmer line emission from the divertor plasmas. During neutral beam heating, PDX divertor discharges were characterized by a sharp transition at which time the main chamber plasma density increased rapidly, the divertor H α emission dropped, and the global energy confinement increased abruptly. At later times, edge relaxation oscillations, characterized by spikes in the H α emission, occurred and were accompanied by a clamp in the density rise and lower confinement time. Limited scans of the temperature and density measured by the divertor probe indicated that these parameters changed with discharge conditions primarily near the separatrix. With the onset of neutral beam injection the temperature and density rose by a factor of 1.5 and 2-4 respectively. Transient drops in Te to values as low as 2 eV and concomitant rises in ne were sometimes observed near the time of the transition into the high confinement mode. Later in the discharge, the values returned to their pre-H-mode level. TV camera observations of the divertor probe revealed a "shadow" along the field lines indicating a well-defined flow in the vicinity of the separatrix.

  5. L-H power threshold studies with tungsten/carbon divertor on the EAST tokamak

    NASA Astrophysics Data System (ADS)

    Chen, L.; Xu, G. S.; Gao, W.; Zhang, L.; Nielsen, A. H.; Luo, Z. P.; Si, H.; Wang, Y. M.; Qu, H.; Sun, Z.; Duan, Y. M.; Liu, H. Q.; Wang, S. X.; Li, M. H.; Zhang, X. J.; Wu, B.; Chen, R.; Wang, L.; Wang, H. Q.; Ding, S. Y.; Yan, N.; Liu, S. C.; Shao, L. M.; Zhang, W.; Hu, G. H.; Li, J.; Li, Y. L.; Wu, X. Q.; Zhao, N.; Jia, M. N.

    2016-05-01

    The power threshold for low (L) to high (H) confinement mode transition achieved by radio-frequency heating and molybdenum first wall with lithium coating has been experimentally investigated on the EAST tokamak for two sets of divertor geometries and materials: tungsten/carbon divertor and full carbon divertor. For both sets of divertors, the power threshold was found to decrease with gradual accumulation of the lithium wall coating, suggesting the important role played by the low Z impurities and/or the edge neutral density on the L-H power threshold. When operating in the upper single null configuration, with the ion grad-B drift direction away from the primary X-point, a lower normalized power threshold is observed in EAST with the tungsten/carbon divertor, compared to the carbon divertor after intensive lithium wall coating. A newly installed cryopump increasing the pumping efficiency also plays an important part in the observed lower threshold. In addition, the H-mode in the Quasi-Snowflake divertor configuration has been obtained on EAST, exhibiting higher L-H power threshold compared to the lower single null configuration with similar IP/BT pairs.

  6. Finger wear detection for production line battery tester

    SciTech Connect

    Depiante, Eduardo V.

    1997-01-01

    A method for detecting wear in a battery tester probe. The method includes providing a battery tester unit having at least one tester finger, generating a tester signal using the tester fingers and battery tester unit with the signal characteristic of the electrochemical condition of the battery and the tester finger, applying wavelet transformation to the tester signal including computing a mother wavelet to produce finger wear indicator signals, analyzing the signals to create a finger wear index, comparing the wear index for the tester finger with the index for a new tester finger and generating a tester finger signal change signal to indicate achieving a threshold wear change.

  7. Finger wear detection for production line battery tester

    DOEpatents

    Depiante, E.V.

    1997-11-18

    A method is described for detecting wear in a battery tester probe. The method includes providing a battery tester unit having at least one tester finger, generating a tester signal using the tester fingers and battery tester unit with the signal characteristic of the electrochemical condition of the battery and the tester finger, applying wavelet transformation to the tester signal including computing a mother wavelet to produce finger wear indicator signals, analyzing the signals to create a finger wear index, comparing the wear index for the tester finger with the index for a new tester finger and generating a tester finger signal change signal to indicate achieving a threshold wear change. 9 figs.

  8. Enhanced visible and near-infrared capabilities of the JET mirror-linked divertor spectroscopy system

    SciTech Connect

    Lomanowski, B. A. Sharples, R. M.; Meigs, A. G.; Conway, N. J.; Zastrow, K.-D.; Heesterman, P.; Kinna, D. [EURATOM Collaboration: JET-EFDA Team

    2014-11-15

    The mirror-linked divertor spectroscopy diagnostic on JET has been upgraded with a new visible and near-infrared grating and filtered spectroscopy system. New capabilities include extended near-infrared coverage up to 1875 nm, capturing the hydrogen Paschen series, as well as a 2 kHz frame rate filtered imaging camera system for fast measurements of impurity (Be II) and deuterium Dα, Dβ, Dγ line emission in the outer divertor. The expanded system provides unique capabilities for studying spatially resolved divertor plasma dynamics at near-ELM resolved timescales as well as a test bed for feasibility assessment of near-infrared spectroscopy.

  9. Trigger finger, tendinosis, and intratendinous gene expression.

    PubMed

    Lundin, A-C; Aspenberg, P; Eliasson, P

    2014-04-01

    The pathogenesis of trigger finger has generally been ascribed to primary changes in the first annular ligament. In contrast, we recently found histological changes in the tendons, similar to the findings in Achilles tendinosis or tendinopathy. We therefore hypothesized that trigger finger tendons would show differences in gene expression in comparison to normal tendons in a pattern similar to what is published for Achilles tendinosis. We performed quantitative real-time polymerase chain reaction on biopsies from finger flexor tendons, 13 trigger fingers and 13 apparently healthy control tendons, to assess the expression of 10 genes which have been described to be differently expressed in tendinosis (collagen type 1a1, collagen 3a1, MMP-2, MMP-3, ADAMTS-5, TIMP-3, aggrecan, biglycan, decorin, and versican). In trigger finger tendons, collagen types 1a1 and 3a1, aggrecan and biglycan were all up-regulated, and MMP-3and TIMP-3 were down-regulated. These changes were statistically significant and have been previously described for Achilles tendinosis. The remaining four genes were not significantly altered. The changes in gene expression support the hypothesis that trigger finger is a form of tendinosis. Because trigger finger is a common condition, often treated surgically, it could provide opportunities for clinical research on tendinosis. PMID:22882155

  10. Fatigue and Motor Redundancy: Adaptive Increase in Finger Force Variance in Multi-Finger Tasks

    PubMed Central

    Singh, Tarkeshwar; SKM, Varadhan; Zatsiorsky, Vladimir M.

    2010-01-01

    We studied the effects of fatigue of the index finger on indices of force variability in discrete and rhythmic accurate force production tasks performed by the index finger and by all four fingers pressing in parallel. An increase in the variance of the force produced by the fatigued index finger was expected. We hypothesized that the other fingers would also show increased variance of their forces, which would be accompanied by co-variation among the finger forces resulting in relatively preserved accuracy of performance. The subjects performed isometric tasks including maximal voluntary contraction (MVC) and accurate force production before and after a 1-min MVC fatiguing exercise by the index finger. During fatigue, there was a significant increase in the root mean square index of force variability during accurate force production by the index finger. In the four-finger tasks, the variance of the individual finger force increased for all four fingers, while the total force variance showed only a modest change. We quantified two components of variance in the space of hypothetical commands to fingers, finger modes. There was a large increase in the variance component that did not affect total force and a much smaller increase in the component that did. The results suggest an adaptive increase in force variance by nonfatigued elements as a strategy to attenuate effects of fatigue on accuracy of multi-element performance. These effects were unlikely to originate at the level of synchronization of motor units across muscle compartments but rather involved higher control levels. PMID:20357060

  11. Is Carbon a Realistic Choice for ITER's Divertor?

    SciTech Connect

    C.H. Skinner; G. Federici

    2005-05-13

    Tritium retention by co-deposition with carbon on the divertor target plate is predicted to limit ITER's DT burning plasma operations (e.g. to about 100 pulses for the worst conditions) before the in-vessel tritium inventory limit, currently set at 350 g, is reached. At this point, ITER will only be able to continue its burning plasma program if technology is available that is capable of rapidly removing large quantities of tritium from the vessel with over 90% efficiency. The removal rate required is four orders of magnitude faster than that demonstrated in current tokamaks. Eighteen years after the observation of co-deposition on JET and TFTR, such technology is nowhere in sight. The inexorable conclusion is that either a major initiative in tritium removal should be funded or that research priorities for ITER should focus on metal alternatives.

  12. Prediction of Pressure Drop in the ITER Divertor Cooling Channels

    SciTech Connect

    Yin, S.T.; Chen, J.L.

    2005-04-15

    This study investigated the pressure drop in the divertor cooling channels of the International Thermonuclear Experimental Reactor (ITER). The water in the cooling channels will encounter the following flow and boiling regimes: 1) single-phase convection, 2) highly-subcooled boiling, 3) onset of nucleate boiling (ONB), and 4) fully-developed subcooled boiling. The upper operating boundary is limited by the departure from nucleate boiling (DNB) or burnout conditions. Twisted-tape insert will be used to enhance local heat transfer. Analytical models, validated with relevant databases, were proposed for the above-identified flow regimes. A user-friendly computer code was developed to calculate the overall pressure drop and the exit pressure of a specific local segment throughout the entire flow circuit. Although the operating parameters were based on the CDA phase input the results are found in general agreement when compared with the ITER EDA results.

  13. Performance of JT-60SA divertor Thomson scattering diagnostics

    SciTech Connect

    Kajita, Shin; Hatae, Takaki; Tojo, Hiroshi; Hamano, Takashi; Shimizu, Katsuhiro; Kawashima, Hisato; Enokuchi, Akito

    2015-08-15

    For the satellite tokamak JT-60 Super Advanced (JT-60SA), a divertor Thomson scattering measurement system is planning to be installed. In this study, we improved the design of the collection optics based on the previous one, in which it was found that the solid angle of the collection optics became very small, mainly because of poor accessibility to the measurement region. By improvement, the solid angle was increased by up to approximately five times. To accurately assess the measurement performance, background noise was assessed using the plasma parameters in two typical discharges in JT-60SA calculated from the SONIC code. Moreover, the influence of the reflection of bremsstrahlung radiation by the wall is simulated by using a ray tracing simulation. The errors in the temperature and the density are assessed based on the simulation results for three typical field of views.

  14. Flute instability and the associated radial transport in the tandem mirror with a divertor mirror cell

    SciTech Connect

    Katanuma, I.; Yagi, K.; Haraguchi, Y.; Ichioka, N.; Masaki, S.; Ichimura, M.; Imai, T.

    2010-11-15

    The flute instability and the associated radial transport are investigated in the tandem mirror with a divertor mirror cell (the GAMMA10 A-divertor) with help of computer simulation, where GAMMA10 is introduced [Inutake et al., Phys. Rev. Lett. 55, 939 (1985)]. The basic equations used in the simulation were derived on the assumption of an axisymmetric magnetic field. So the high plasma pressure in a nonaxisymmetric minimum-B anchor mirror cell, which is important for the flute mode stability, is taken into account by redefining the specific volume of a magnetic field line. It is found that the flute modes are stabilized by the minimum-B magnetic field even with a divertor mirror although its stabilizing effects are weaker than that without the divertor mirror. The flute instability enhances the radial transport by intermittently repeating the growing up and down of the Fourier amplitude of the flute instability in time.

  15. Divertor electron temperature and impurity diffusion measurements with a spectrally resolved imaging radiometer

    SciTech Connect

    Clayton, D. J.; Kumar, D.; Stutman, D.; Finkenthal, M.; Tritz, K.; Jaworski, M. A.

    2012-10-15

    A divertor imaging radiometer (DIR) diagnostic is being studied to measure spatially and spectrally resolved radiated power P{sub rad}({lambda}) in the tokamak divertor. A dual transmission grating design, with extreme ultraviolet ({approx}20-200 A) and vacuum ultraviolet ({approx}200-2000 A) gratings placed side-by-side, can produce coarse spectral resolution over a broad wavelength range covering emission from impurities over a wide temperature range. The DIR can thus be used to evaluate the separate P{sub rad} contributions from different ion species and charge states. Additionally, synthetic spectra from divertor simulations can be fit to P{sub rad}({lambda}) measurements, providing a powerful code validation tool that can also be used to estimate electron divertor temperature and impurity transport.

  16. Development of microwave interferometer system for divertor simulation experiments in GAMMA 10/PDX

    NASA Astrophysics Data System (ADS)

    Kohagura, J.; Wang, X.; Kanno, S.; Yoshikawa, M.; Kuwahara, D.; Nagayama, Y.; Shima, Y.; Chikatsu, M.; Nojiri, K.; Sakamoto, M.; Imai, T.; Nakashima, Y.; Mase, A.

    2015-12-01

    Microwave interferometer has newly been installed on GAMMA 10/PDX for divertor simulation study. A divertor simulation experimental module (D-module) is used to investigate the physics of divertor in the end-cell of GAMMA 10/PDX where an open magnetic field configuration is formed. D-module has a rectangular chamber with an inlet aperture. Two tungsten target plates are mounted in V-shape inside the chamber. In order to develop understandings of divertor simulation experiments the microwave interferometer using heterodyne scheme and a 1D horn-antenna mixer array (HMA) is applied to obtain electron density and density distribution inside the V-shaped target plates. Line-averaged electron density distributions inside D-module are first observed in H2 gas injection experiments.

  17. Design of a diagnostic residual gas analyzer for the ITER divertor

    SciTech Connect

    Klepper, C Christopher; Biewer, T. M.; Graves, Van B; Andrew, P.; Marcus, Chris; Shimada, M.; Hughes, S.; Boussier, B.; Johnson, D. W.; Gardner, W. L.; Hillis, D. L.; Vayakis, G.; Vayakis, G.; Walsh, M.

    2015-01-01

    One of the ITER diagnostics having reached an advanced design stage is a diagnostic RGA for the divertor, i.e. residual gas analysis system for the ITER divertor, which is intended to sample the divertor pumping duct region during the plasma pulse and to have a response time compatible with plasma particle and impurity lifetimes in the divertor region. Main emphasis is placed on helium (He) concentration in the ducts, as well as the relative concentration between the hydrogen isotopes (H2, D2, T2). Measurement of the concentration of radiative gases, such as neon (Ne) and nitrogen (N2), is also intended. Numerical modeling of the gas flow from the sampled region to the cluster of analysis sensors, through a long (~8m long, ~110mm diameter) sampling pipe terminating in a pressure reducing orifice, confirm that the desired response time (~1s for He or D2) is achieved with the present design.

  18. Super Bubble and For Fingers Only.

    ERIC Educational Resources Information Center

    Barrow, Lloyd H.; And Others

    1997-01-01

    Presents two activities, the "Super Bubble" that challenges students and parents to blow the biggest bubbles and "For Fingers Only" that asks them to duplicate a pattern of blocks using only the sense of touch. (JRH)

  19. Finger necrosis after accidental radial artery puncture

    PubMed Central

    Kang, Jun Sik; Lee, Tae Rim; Cha, Won Chul; Shin, Tae Gun; Sim, Min Seob; Jo, Ik Joon; Song, Keun Jeong; Rhee, Joong Eui; Jeong, Yeon Kwon

    2014-01-01

    Radial artery puncture, an invasive procedure, is frequently used for critical patients. Although considered safe, severe complications such as finger necrosis can occur. Herein, we review the clinical course of finger necrosis after accidental radial artery puncture. A 63-year-old woman visited the emergency department (ED) with left second and third finger pain after undergoing intravenous (IV) access in her wrist for procedural sedation. During the IV access, she experienced wrist pain, which increased during the 12 hours prior to her ED presentation. Emergency angiography revealed a pseudoaneurysm in her left radial artery and absence of blood flow to the proper palmar digital artery. Subsequent angiointervention and urokinase thrombolysis failed. The second finger was eventually amputated owing to gangrene. Radial artery puncture can occur accidentally during IV wrist access, resulting in severe morbidity. Providers should carefully examine the puncture site and collateral flow, followed by multiple examinations to ensure distal circulation.

  20. The Two-Dimensional Structure of Partially Detached Divertor Plasmas in the DIII--D Tokamak

    NASA Astrophysics Data System (ADS)

    Fenstermacher, M. E.

    1996-11-01

    In this paper we present recent measurements of the 2-D spatial profiles of divertor plasma density, temperature, and emissivity in the DIII--D tokamak under highly radiating conditions in which there is a strong reduction in plasma pressure and energy conduction along the open field lines of the scrape-off layer (Partially Detached Divertor). This regime is desirable because the energy flux to the divertor targets can be reduced by up to a factor of 10 by the increased radiation, thus allowing for reliable divertor designs in high power tokamaks such as ITER. The data presented here are obtained using a newly installed Divertor Thomson Scattering (DTS) system specifically optimized for measuring the high electron densities and low temperatures expected in these detached divertor plasmas (ne <= 10^21 m-3, 0.5 eV <= T_e). These data are correlated with simultaneous measurements from fixed and fast-plunging Langmuir probes, VUV spectrometers, bolometers, and visible-light TV cameras. The DTS data confirm that electron pressure is nearly constant along field lines in attached plasmas, consistent with upstream and target plate diagnostics. D2 gas puffing in the divertor increases the plasma radiation and lowers Te to <2 eV in most of the divertor volume. Modeling shows that this temperature is low enough to allow ion-neutral collisions, charge exchange, and volume recombination to play significant roles in reducing the electron pressure along the magnetic separatrix by 3--5×, consistent with the measurements. At these temperatures, molecules may also be present in significant numbers and can further increase the recombination rates (Krasheninnikov, et al., J. Nucl. Mater. 1996). Farther out in the SOL, the electron density and pressure rise to values higher than those on the same flux surface at the midplane, so only part of the divertor plasma is detached. Absolutely-calibrated VUV spectroscopy and 2-D images of impurity emission show that the reduction in Te results

  1. Overview of Stellarator Divertor Studies: Final Report of LDRD Project 01-ERD-069

    SciTech Connect

    Fenstermacher, M E; Rognlien, T D; Koniges, A; Unmansky, M; Hill, D N

    2003-01-21

    A summary is given of the work carried out under the LDRD project 01-ERD-069 entitled Stellarator Divertor Studies. This project has contributed to the development of a three-dimensional edge-plasma modeling and divertor diagnostic design capabilities at LLNL. Results are demonstrated by sample calculations and diagnostic possibilities for the edge plasma of the proposed U.S. National Compact Stellarator Experiment device. Details of the work are contained in accompanying LLNL reports that have been accepted for publication.

  2. Survivability of dust in tokamaks: Dust transport in the divertor sheath

    SciTech Connect

    Delzanno, Gian Luca; Tang, Xianzhu

    2014-02-15

    The survivability of dust being transported in the magnetized sheath near the divertor plate of a tokamak and its impact on the desired balance of erosion and redeposition for a steady-state reactor are investigated. Two different divertor scenarios are considered. The first is characterized by an energy flux perpendicular to the plate q{sub 0}≃1 MW/m{sup 2} typical of current short-pulse tokamaks. The second has q{sub 0}≃10 MW/m{sup 2} and is relevant to long-pulse machines like ITER or Demonstration Power Plant. It is shown that micrometer dust particles can survive rather easily near the plates of a divertor plasma with q{sub 0}≃1 MW/m{sup 2} because thermal radiation provides adequate cooling for the dust particle. On the other hand, the survivability of micrometer dust particles near the divertor plates is drastically reduced when q{sub 0}≃10 MW/m{sup 2}. Micrometer dust particles redeposit their material non-locally, leading to a net poloidal mass migration across the divertor. Smaller particles (with radius ∼0.1 μm) cannot survive near the divertor and redeposit their material locally. Bigger particle (with radius ∼10 μm) can instead survive partially and move outside the divertor strike points, thus causing a net loss of divertor material to dust accumulation inside the chamber and some non-local redeposition. The implications of these results for ITER are discussed.

  3. Design and analysis of the DII-D radiative divertor water-cooled structures

    SciTech Connect

    Hollerbach, M.A.; Smith, J.P.; Baxi, C.B.; Bozek; Chin, E.; Phelps, R.D.; Redler, K.M.; Reis, E.E.

    1995-10-01

    The Radiative Divertor is a major modification to the divertor of DIII-D and is being designed and fabricated for installation in late 1996. The Radiative Divertor Program (RDP) will enhance the dissipative processes in the edge and divertor plasmas to reduce the heat flux and plasma erosion at the divertor target. This approach will have major implications for the heat removal methods used in future devices. The divertor is of slot-type configuration designed to minimize the flow of sputtered and injected impurities back to the core plasma. The new divertor will be composed of toroidally continuous, Inconel 625 water-cooled rings of sandwich construction with an internal water channel, incorporating seam welding to provide the water-to-vacuum seal as well as structural integrity. The divertor structure is designed to withstand electromagnetic loads as a result of halo currents and induced toroidal currents. It also accommodates the thermal differences experienced during the 400 {degrees}C bake used on DIII-D. A low Z plasma-facing surface is provided by mechanically attached graphite tiles. Water flow through the rings will inertially cool these tiles which will be subjected to 38 MW, 10 second pulses. Current schedules call for detailed design in 1996 with installation completed in March 1997. A full size prototype, one-quarter of one ring, is being built to validate manufacturing techniques, machining, roll-forming, and seam welding. The experience and knowledge gained through the fabrication of the prototype is discussed. The design of the electrically isolated (5 kV) vacuum-to-air water feedthroughs supplying the water-cooled rings is also discussed.

  4. [Ulnar sesamoid bone of the small finger causing painful trigger finger].

    PubMed

    Stahlenbrecher, A; Hoch, J

    2006-04-01

    We report on a 38-year-old woman suffering from painful trigger finger. Contrary to the expected intraoperative finding of a simple stenosing pulley and ganglion cyst on a thickened flexor tendon sheath, we found fibrotic cords between an abnormal ulnar sesamoid bone at the fifth finger and the A1-pulley to be responsible for distortion of the tendon sheath and a consecutive "klicking"-phenomenon. A coherence between sesamoid bones and trigger finger has repeatedly been found on the thumb but there is no such description regarding the long fingers. PMID:16680671

  5. Finger Cooling During Cold Air Exposure.

    NASA Astrophysics Data System (ADS)

    Tikuisis, Peter

    2004-05-01

    This paper presents a method for predicting the onset of finger freezing. It is an extension of a tissue-cooling model originally developed to predict the onset of cheek freezing. The extension to the finger is presented as a more conservative warning of wind chill. Indeed, guidance on the risk of finger freezing is important not only to safeguard the finger, but also because it pertains more closely to susceptible facial features, such as the nose, than if only the risk of cheek freezing was provided. The importance of blood flow to the finger and the modeling of vaso-constriction are demonstrated through cooling predictions that agree reasonably well with several reported observations. Differences in the prediction between the present physiologic-based model and the engineering model used to develop the wind chill index are also discussed. New wind chill charts are presented that tabulate the mean cooling rates and corresponding onset times to freezing of the finger for various combinations of air temperature and wind speed. Results indicate that the surface of the finger cools to its freezing point in approximately one-eighth of the time predicted for the cheek. For combinations that result in the same wind chill temperature (WCT), the rate of finger cooling is faster at the higher wind speed. This asymmetry was previously disclosed through the application of the model to cheek cooling, and it reiterates the ambiguity associated with the reporting of WCT. It is further emphasized that the reporting of onset times to freezing, or safe exposure limits, is a more logical and meaningful alternative to the WCT.

  6. Histopathology of tenosynovium in trigger fingers.

    PubMed

    Uchihashi, Kazuyoshi; Tsuruta, Toshiyuki; Mine, Hiroko; Aoki, Shigehisa; Nishijima-Matsunobu, Aki; Yamamoto, Mihoko; Kuraoka, Akio; Toda, Shuji

    2014-06-01

    Stenosing flexor tenosynovitis, trigger finger, is a common clinical disorder causing painful locking or contracture of the involved digits, and most instances are idiopathic. This problem is generally caused by a size mismatch between the swollen flexor tendon and the thickened first annular pulley. Although hypertrophic pulleys have been histologically and ultrasonographically detected, little is known about the histopathology of the tenosynovium covering the tendons of trigger fingers. We identified chondrocytoid cells that produced hyaluronic acid in 23 (61%) fingers and hypocellular collagen matrix in 32 (84%) fingers around the tenosynovium among 38 specimens of tenosynovium from patients with trigger fingers. These chondrocytoid cells expressed the synovial B cell marker CD44, but not the chondrocyte marker S-100 protein. The incidence of these findings was much higher than that of conventional findings of synovitis, such as inflammatory infiltrate (37%), increased vascularity (37%), hyperplasia of synovial lining cells (21%), or fibrin exudation (5%). We discovered the following distinctive histopathological features of trigger finger: hyaluronic acid-producing chondrocytoid cells originated from fibroblastic synovial B cells, and a hypocellular collagen matrix surrounding the tenosynovium. Thus, an edematous extracellular matrix with active hyaluronic acid synthesis might increase pressure under the pulley and contribute to the progression of stenosis. PMID:24965110

  7. Viscous fingering in a microfluidic network

    NASA Astrophysics Data System (ADS)

    Budek, Agnieszka; Garstecki, Piotr; Samborski, Adam; Szymczak, Piotr

    2014-05-01

    We study experimentally and numerically two-phase flow in a rectangular network of microfluidic channels. If the pressure gradient is oriented along the lattice, growth of long and thin dendrites ('thin fingers') is promoted. The dynamics of thin finger growth is of interest due to their appearance in a variety of other pattern forming systems, such as the growth of dendrites in electrochemical deposition experiments, channeling in dissolving rocks or side-branches growth in crystallization. Due to their simplicity, thin finger models are also attractive for theoretical analysis. A characteristic feature of these systems is a strong competition between the fingers which is a reflection of Saffman-Taylor instability acting in a nonlinear regime. Surprisingly, the case of miscible fluids turns out to be different, with the competition between the fingers hindered due to the strong lateral currents of the displaced fluid, which eventually cut off the heads of the advancing fingers, thus preventing their further growth. The heads continue to move through the system, preserving their shapes, thus forming the 'miscible droplets'. In immiscible case this process is hindered by the presence of the surface tension. A detailed analysis of this phenomenon is given with a particular emphasis on the scaling properties of the system.

  8. Fingering convection in red giants revisited

    NASA Astrophysics Data System (ADS)

    Wachlin, F. C.; Vauclair, S.; Althaus, L. G.

    2014-10-01

    Context. Fingering (thermohaline) convection has been invoked for several years as a possible extra-mixing which could occur in red giant stars; it is due to the modification of the chemical composition induced by nuclear reactions in the hydrogen burning zone. Recent studies show, however, that this mixing is not sufficient to account for the needed surface abundances. Aims: A new prescription for fingering convection, based on 3D numerical simulations has recently been proposed. The resulting mixing coefficient is larger than those previously given in the literature. We compute models using this new coefficient and compare them to previous studies. Methods: We used the LPCODE stellar evolution code with a generalized version of the mixing length theory to compute red giant models and we introduce fingering convection using the BGS prescription. Results: The results show that, although the fingering zone now reaches the outer dynamical convective zone, the efficiency of the mixing is not enough to account for the observations. The fingering mixing coefficient should be increased by two orders of magnitude for the needed surface abundances to be reached. Conclusions: We confirm that fingering convection cannot be the mixing process needed to account for surface abundances in red giant branch stars.

  9. New Finger Biometric Method Using Near Infrared Imaging

    PubMed Central

    Lee, Eui Chul; Jung, Hyunwoo; Kim, Daeyeoul

    2011-01-01

    In this paper, we propose a new finger biometric method. Infrared finger images are first captured, and then feature extraction is performed using a modified Gaussian high-pass filter through binarization, local binary pattern (LBP), and local derivative pattern (LDP) methods. Infrared finger images include the multimodal features of finger veins and finger geometries. Instead of extracting each feature using different methods, the modified Gaussian high-pass filter is fully convolved. Therefore, the extracted binary patterns of finger images include the multimodal features of veins and finger geometries. Experimental results show that the proposed method has an error rate of 0.13%. PMID:22163741

  10. Spectroscopic imaging system for quantitative analysis of the divertor plasma of the Tokamak de Varennes

    SciTech Connect

    Meo, F.; Stansfield, B.L.; Chartre, M.; de Villers, P.; Marchand, R.; Ratel, G.

    1997-09-01

    A toroidally viewing spectroscopic imaging system has been developed for the Tokamak de Varennes providing measurements of the poloidal distribution of the absolute radiated power of deuterium and impurity species in the upper divertor region. Real time digitization is achieved using a low cost PC based digital imaging system. This system is used to obtain measurements of the divertor strike point as well as the shape of the flux surfaces in the divertor. The diagnostic{close_quote}s excellent spatial resolution and toroidal view provides an opportunity to quantitatively compare the measured two dimensional (2D) radiated power distribution to that calculated from 2D Monte Carlo transport codes. These 2D images provide unique and valuable information on the physics of local plasma interactions with divertor components and particle transport in a closed divertor. Additionally, by using two cameras simultaneously, the line ratio technique can be applied to the images to estimate plasma parameters in the divertor. {copyright} {ital 1997 American Institute of Physics. }

  11. Favorable effects of turbulent plasma mixing on the performance of innovative tokamak divertors

    NASA Astrophysics Data System (ADS)

    Ryutov, D. D.; Cohen, R. H.; Rognlien, T. D.; Umansky, M. V.

    2013-10-01

    The problem of reducing the heat load on plasma-facing components is one of the most demanding issues for MFE devices. The general approach to the solution of this problem is the use of a specially configured poloidal magnetic field, so called magnetic divertors. In recent years, novel divertors possessing the 2-nd and 3-rd order nulls of the poloidal field (PF) have been proposed. They are called a ``snowflake'' (SF) and a ``cloverleaf'' (CL) divertor, respectively, due to characteristic shape of the magnetic separatrix. Among several beneficial features of such divertors is an effect of strong turbulent plasma mixing that is intrinsic to the zone of weak PF near the null-point. The turbulence spreads the heat flux between multiple divertor exhaust channels and increases the heat flux width within each channel. Among physical processes affecting the onset of convection the curvature-driven mode of axisymmetric rolls is most prominent. The effect is quite significant for the SF and is even stronger for the CL divertor. Projections to future ITER-scale facilities are discussed. Work performed for U.S. DoE by LLNL under Contract DE-AC52-07NA27344.

  12. Critical need for MFE: the Alcator DX advanced divertor test facility

    NASA Astrophysics Data System (ADS)

    Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Wolf, S.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hutchinson, I.; Hubbard, A.; Hughes, J.; Lin, Y.; Lipschultz, B.; Parker, R.; Porkolab, M.; Reinke, M.; Rice, J.; Shiraiwa, S.; Terry, J.; Theiler, C.; Wallace, G.; White, A.; Whyte, D.; Wukitch, S.

    2013-10-01

    Three critical challenges must be met before a steady-state, power-producing fusion reactor can be realized: how to (1) safely handle extreme plasma exhaust power, (2) completely suppress material erosion at divertor targets and (3) do this while maintaining a burning plasma core. Advanced divertors such as ``Super X'' and ``X-point target'' may allow a fully detached, low temperature plasma to be produced in the divertor while maintaining a hot boundary layer around a clean plasma core - a potential game-changer for magnetic fusion. No facility currently exists to test these ideas at the required parallel heat flux densities. Alcator DX will be a national facility, employing the high magnetic field technology of Alcator combined with high-power ICRH and LHCD to test advanced divertor concepts at FNSF/DEMO power exhaust densities and plasma pressures. Its extended vacuum vessel contains divertor cassettes with poloidal field coils for conventional, snowflake, super-X and X-point target geometries. Divertor and core plasma performance will be explored in regimes inaccessible in conventional devices. Reactor relevant ICRF and LH drivers will be developed, utilizing high-field side launch platforms for low PMI. Alcator DX will inform the conceptual development and accelerate the readiness-for-deployment of next-step fusion facilities.

  13. A Fast Visible Camera Divertor-Imaging Diagnostic on DIII-D

    SciTech Connect

    Roquemore, A; Maingi, R; Lasnier, C; Nishino, N; Evans, T; Fenstermacher, M; Nagy, A

    2007-06-19

    In recent campaigns, the Photron Ultima SE fast framing camera has proven to be a powerful diagnostic when applied to imaging divertor phenomena on the National Spherical Torus Experiment (NSTX). Active areas of NSTX divertor research addressed with the fast camera include identification of types of EDGE Localized Modes (ELMs)[1], dust migration, impurity behavior and a number of phenomena related to turbulence. To compare such edge and divertor phenomena in low and high aspect ratio plasmas, a multi-institutional collaboration was developed for fast visible imaging on NSTX and DIII-D. More specifically, the collaboration was proposed to compare the NSTX small type V ELM regime [2] and the residual ELMs observed during Type I ELM suppression with external magnetic perturbations on DIII-D[3]. As part of the collaboration effort, the Photron camera was installed recently on DIII-D with a tangential view similar to the view implemented on NSTX, enabling a direct comparison between the two machines. The rapid implementation was facilitated by utilization of the existing optics that coupled the visible spectral output from the divertor vacuum ultraviolet UVTV system, which has a view similar to the view developed for the divertor tangential TV camera [4]. A remote controlled filter wheel was implemented, as was the radiation shield required for the DIII-D installation. The installation and initial operation of the camera are described in this paper, and the first images from the DIII-D divertor are presented.

  14. Characterization of energetic deuterium striking the divertor of the DIII-D tokamak

    SciTech Connect

    Bastasz, R.; Wampler, W.R.; Whaley, J.A.; Whyte, D.G.; Parks, P.B.; Brooks, N.H.; West, W.P.; Wong, C.P.C.

    1996-06-01

    The flux and energy of particles striking the divertor during steady state operation and during disruptions are parameters of central interest in the design of power producing tokamaks. The energetic particle flux to the divertor is a critical factor, as it has a large effect on material behavior and the lifetime of plasma-facing components. Here, measurements of the deuterium particle flux and energy to the divertor of the DIII-D tokamak during a series of plasmas that terminated in disruptions have been made using a silicon collector probe installed on the divertor materials exposure system (DiMES). During the steady state portion of each discharge, the probe was located under the separatrix, but immediately before disrupting the plasma, by injecting either Ar or D{sub 2} gas, the strike point of the outer divertor leg was positioned over the probe. Comparison of the amount of retained D in the probe for the two types of disruptions indicates that much of the trapped D could have resulted from exposure in the private flux zone prior to the disruption. Measurements of the depth distribution of the trapped D in the Si imply that the incident ion energy was approximately 100 eV at normal incidence and decreased slightly at oblique angles. The measurements give an upper bound to the energy of deuterons striking the divertor floor in the vicinity of the strikepoint during disruptions.

  15. Exploration of magnetic perturbation effects on advanced divertor configurations in NSTX-U

    NASA Astrophysics Data System (ADS)

    Frerichs, H.; Schmitz, O.; Waters, I.; Canal, G. P.; Evans, T. E.; Feng, Y.; Soukhanovskii, V. A.

    2016-06-01

    The control of divertor heat loads - both steady state and transient - remains a key challenge for the successful operation of ITER and FNSF. Magnetic perturbations provide a promising technique to control ELMs (Edge Localized Modes) (transients), but understanding their detailed impact is difficult due to their symmetry breaking nature. One approach for reducing steady state heat loads is so called "advanced divertors" which aim at optimizing the magnetic field configuration: the snowflake and the (super-)X-divertor. It is likely that both concepts - magnetic perturbations and advanced divertors - will have to work together, and we explore their interaction based on the NSTX-U setup. An overview of different divertor configurations under the impact of magnetic perturbations is presented, and the resulting impact on plasma edge transport is investigated with the EMC3-EIRENE code. Variations in size of the magnetic footprint of the perturbed separatrix are found, which are related to the level of flux expansion on the divertor target. Non-axisymmetric peaking of the heat flux related to the perturbed separatrix is found at the outer strike point, but only in locations where flux expansion is not too large.

  16. Divertor Target Heat Load Reduction by Electrical Biasing, and Application to COMPASS-D

    SciTech Connect

    Fielding, S J; Cohen, R H; Helander, P; Ryutov, D D

    2001-03-07

    A toroidally-asymmetric potential structure in the scrape-off layer (SOL) plasma may be formed by toroidally distributed electrical biasing of the divertor target tiles. The resulting ExB convective motions should increase the plasma radial transport in the SOL and thereby reduce the heat load at the divertor [1]. In this paper we develop theoretical modeling and describe the implementation of this concept to the COMPASS-D divertor. We show that strong magnetic shear near the X-point should cause significant squeezing of the convective cells preventing convection from penetrating above the X-point. This should result in reduced heat load at the divertor target without increasing the radial transport in the portion of the SOL in direct contact with the core plasma, potentially avoiding any confinement degradation. implementation of divertor biasing is in hand on COMPASS-D involving insulation of, and modifications to, the present divertor tiles. Calculations based on measured edge parameters suggest that modest currents {approx} 8 A/tile are required, at up to 150V, to drive the convection. A technical test is preceeding full bias experiments.

  17. Design and testing of a superfluid liquid helium cooling loop

    SciTech Connect

    Gavin, L.M.; Green, M.A.; Levin, S.M.; Smoot, G.F.; Witebsky, C.

    1989-07-01

    This paper describes the design and preliminary testing of a cryogenic cooling loop that uses a thermomechanical pump to circulate superfluid liquid helium. The cooling loop test apparatus is designed to prove forced liquid helium flow concepts that will be used on the Astromag superconducting magnet facility. 3 refs., 2 figs.

  18. Sensitive method for characterizing liquid helium cooled preamplifier feedback resistors

    NASA Technical Reports Server (NTRS)

    Smeins, L. G.; Arentz, R. F.

    1983-01-01

    It is pointed out that the simple and traditional method of measuring resistance using an electrometer is ineffective since it is limited to a narrow and nonrepresentative range of terminal voltages. The present investigation is concerned with a resistor measurement technique which was developed to select and calibrate the Transimpedance Mode Amplifier (TIA) load resistors on the Infrared Astronomical Satellite (IRAS) for the wide variety of time and voltage varying signals which will be processed during the flight. The developed method has great versatility and power, and makes it possible to measure the varied and complex responses of nonideal feedback resistors to IR photo-detector currents. When employed with a stable input coupling capacitor, and a narrow band RMS voltmeter, the five input waveforms thouroughly test and calibrate all the features of interest in a load resistor and its associated TIA circuitry.

  19. In-out asymmetry of divertor particle flux in H-mode with edge localized modes on EAST

    NASA Astrophysics Data System (ADS)

    Liu, J. B.; Guo, H. Y.; Wang, L.; Xu, G. S.; Xia, T. Y.; Liu, S. C.; Xu, X. Q.; Li, Jie; Chen, L.; Yan, N.; Wang, H. Q.; Xu, J. C.; Feng, W.; Shao, L. M.; Deng, G. Z.; Liu, H.; EAST Probe Team

    2016-06-01

    The in-out divertor asymmetry in the Experimental Advanced Superconducting Tokamak (EAST), as manifested by particle fluxes measured by the divertor triple Langmuir probe arrays, is significantly enhanced during type-I edge localized modes (ELMs), favoring the inner divertor in lower single null (LSN) for the normal toroidal field (B t) direction, i.e. with the ion B  ×  \

  20. Anthropomorphic finger antagonistically actuated by SMA plates.

    PubMed

    Engeberg, Erik D; Dilibal, Savas; Vatani, Morteza; Choi, Jae-Won; Lavery, John

    2015-10-01

    Most robotic applications that contain shape memory alloy (SMA) actuators use the SMA in a linear or spring shape. In contrast, a novel robotic finger was designed in this paper using SMA plates that were thermomechanically trained to take the shape of a flexed human finger when Joule heated. This flexor actuator was placed in parallel with an extensor actuator that was designed to straighten when Joule heated. Thus, alternately heating and cooling the flexor and extensor actuators caused the finger to flex and extend. Three different NiTi based SMA plates were evaluated for their ability to apply forces to a rigid and compliant object. The best of these three SMAs was able to apply a maximum fingertip force of 9.01N on average. A 3D CAD model of a human finger was used to create a solid model for the mold of the finger covering skin. Using a 3D printer, inner and outer molds were fabricated to house the actuators and a position sensor, which were assembled using a multi-stage casting process. Next, a nonlinear antagonistic controller was developed using an outer position control loop with two inner MOSFET current control loops. Sine and square wave tracking experiments demonstrated minimal errors within the operational bounds of the finger. The ability of the finger to recover from unexpected disturbances was also shown along with the frequency response up to 7 rad s(-1). The closed loop bandwidth of the system was 6.4 rad s(-1) when operated intermittently and 1.8 rad s(-1) when operated continuously. PMID:26292164

  1. Design and preliminary evaluation of the FINGER rehabilitation robot: controlling challenge and quantifying finger individuation during musical computer game play

    PubMed Central

    2014-01-01

    Background This paper describes the design and preliminary testing of FINGER (Finger Individuating Grasp Exercise Robot), a device for assisting in finger rehabilitation after neurologic injury. We developed FINGER to assist stroke patients in moving their fingers individually in a naturalistic curling motion while playing a game similar to Guitar Hero®a. The goal was to make FINGER capable of assisting with motions where precise timing is important. Methods FINGER consists of a pair of stacked single degree-of-freedom 8-bar mechanisms, one for the index and one for the middle finger. Each 8-bar mechanism was designed to control the angle and position of the proximal phalanx and the position of the middle phalanx. Target positions for the mechanism optimization were determined from trajectory data collected from 7 healthy subjects using color-based motion capture. The resulting robotic device was built to accommodate multiple finger sizes and finger-to-finger widths. For initial evaluation, we asked individuals with a stroke (n = 16) and without impairment (n = 4) to play a game similar to Guitar Hero® while connected to FINGER. Results Precision design, low friction bearings, and separate high speed linear actuators allowed FINGER to individually actuate the fingers with a high bandwidth of control (−3 dB at approximately 8 Hz). During the tests, we were able to modulate the subject’s success rate at the game by automatically adjusting the controller gains of FINGER. We also used FINGER to measure subjects’ effort and finger individuation while playing the game. Conclusions Test results demonstrate the ability of FINGER to motivate subjects with an engaging game environment that challenges individuated control of the fingers, automatically control assistance levels, and quantify finger individuation after stroke. PMID:24495432

  2. Quantifying Parkinson's disease finger-tapping severity by extracting and synthesizing finger motion properties.

    PubMed

    Sano, Yuko; Kandori, Akihiko; Shima, Keisuke; Yamaguchi, Yuki; Tsuji, Toshio; Noda, Masafumi; Higashikawa, Fumiko; Yokoe, Masaru; Sakoda, Saburo

    2016-06-01

    We propose a novel index of Parkinson's disease (PD) finger-tapping severity, called "PDFTsi," for quantifying the severity of symptoms related to the finger tapping of PD patients with high accuracy. To validate the efficacy of PDFTsi, the finger-tapping movements of normal controls and PD patients were measured by using magnetic sensors, and 21 characteristics were extracted from the finger-tapping waveforms. To distinguish motor deterioration due to PD from that due to aging, the aging effect on finger tapping was removed from these characteristics. Principal component analysis (PCA) was applied to the age-normalized characteristics, and principal components that represented the motion properties of finger tapping were calculated. Multiple linear regression (MLR) with stepwise variable selection was applied to the principal components, and PDFTsi was calculated. The calculated PDFTsi indicates that PDFTsi has a high estimation ability, namely a mean square error of 0.45. The estimation ability of PDFTsi is higher than that of the alternative method, MLR with stepwise regression selection without PCA, namely a mean square error of 1.30. This result suggests that PDFTsi can quantify PD finger-tapping severity accurately. Furthermore, the result of interpreting a model for calculating PDFTsi indicated that motion wideness and rhythm disorder are important for estimating PD finger-tapping severity. PMID:27032933

  3. Individual variability in finger-to-finger transmission efficiency of Enterococcus faecium clones

    PubMed Central

    del Campo, Rosa; Sánchez-Díaz, Ana María; Zamora, Javier; Torres, Carmen; Cintas, Luis María; Franco, Elvira; Cantón, Rafael; Baquero, Fernando

    2014-01-01

    A fingertip-to-fingertip intraindividual transmission experiment was carried out in 30 healthy volunteers, using four MLST-typed Enterococcus faecium clones. Overall results showed an adequate fit goodness to a theoretical exponential model, whereas four volunteers (13%) exhibited a significantly higher finger-to-finger bacterial transmission efficiency. This observation might have deep consequences in nosocomial epidemiology. PMID:24382843

  4. Individual variability in finger-to-finger transmission efficiency of Enterococcus faecium clones.

    PubMed

    del Campo, Rosa; Sánchez-Díaz, Ana María; Zamora, Javier; Torres, Carmen; Cintas, Luis María; Franco, Elvira; Cantón, Rafael; Baquero, Fernando

    2014-02-01

    A fingertip-to-fingertip intraindividual transmission experiment was carried out in 30 healthy volunteers, using four MLST-typed Enterococcus faecium clones. Overall results showed an adequate fit goodness to a theoretical exponential model, whereas four volunteers (13%) exhibited a significantly higher finger-to-finger bacterial transmission efficiency. This observation might have deep consequences in nosocomial epidemiology. PMID:24382843

  5. Ultrafast High-Resolution Mass Spectrometric Finger Pore Imaging in Latent Finger Prints

    NASA Astrophysics Data System (ADS)

    Elsner, Christian; Abel, Bernd

    2014-11-01

    Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record `three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high- spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals.

  6. Ultrafast High-Resolution Mass Spectrometric Finger Pore Imaging in Latent Finger Prints

    PubMed Central

    Elsner, Christian; Abel, Bernd

    2014-01-01

    Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record ‘three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high- spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals. PMID:25366032

  7. Reconstruction of Extensive Volar Finger Defects with Double Cross-Finger Flaps

    PubMed Central

    Buehrer, Gregor; Arkudas, Andreas; Ludolph, Ingo; Horch, Raymund E.

    2016-01-01

    Summary: Cross-finger flaps still represent a viable option to reconstruct small- to medium-sized full-thickness finger defects but they are not commonly used if larger areas have to be covered. We present 2 cases showing a simple and pragmatic approach with homodigital double cross-finger flaps to reconstruct extensive volar finger soft-tissue defects. We observed very low donor-site morbidity and excellent functional and aesthetic outcomes. Furthermore, there is no need for microsurgical techniques or equipment when using this method. Although this case report only addresses volar defects, one might also think of applying this concept to dorsal defects using reversed double cross-finger flaps. PMID:27200255

  8. Salt finger signatures in microstructure measurements

    NASA Astrophysics Data System (ADS)

    Hamilton, J. M.; Oakey, N. S.; Kelley, D. E.

    1993-02-01

    By measuring the "scaled dissipation ratio" Γ, which is the relative magnitude of the dissipation of thermal variance compared with the dissipation of turbulent kinetic energy, one can distinguish between salt fingering and nonfingering regimes. This is illustrated by comparing data from three test cases to predictions from (1) a mixing model which considers turbulence only and (2) a model which describes salt fingers as the sole mixing process. In a turbulent, nondouble-diffusive surface layer we find that measurements of Γ are very close to the value predicted by the turbulent mixing model. A contrasting case is provided by a thermohaline staircase located at 1200- to 1330-m depth. There the salt finger model provides a better description of the mixing than does the turbulent mixing model. The third case study is of measurements between 150 and 400 m where the water column is characterized by low density ratios and "intermittent steppiness" in temperature and salinity profiles. Here, values of Γ are inconsistent with a model containing only salt finger or turbulent mixing; instead, the observations suggest that both processes are important. Using the observed values of Γ in a combined model suggests that 24% of the observed turbulent kinetic energy dissipation is due to salt fingers. A corresponding estimate of the vertical eddy diffusivity of salt (and nutrients) is 2 times larger than that computed from the turbulence-only mixing model and 50% larger than the vertical eddy diffusivity for heat as determined by the Osborn-Cox relation.

  9. Saffman-Taylor fingers with kinetic undercooling

    NASA Astrophysics Data System (ADS)

    Gardiner, Bennett P. J.; McCue, Scott W.; Dallaston, Michael C.; Moroney, Timothy J.

    2015-02-01

    The mathematical model of a steadily propagating Saffman-Taylor finger in a Hele-Shaw channel has applications to two-dimensional interacting streamer discharges which are aligned in a periodic array. In the streamer context, the relevant regularization on the interface is not provided by surface tension but instead has been postulated to involve a mechanism equivalent to kinetic undercooling, which acts to penalize high velocities and prevent blow-up of the unregularized solution. Previous asymptotic results for the Hele-Shaw finger problem with kinetic undercooling suggest that for a given value of the kinetic undercooling parameter, there is a discrete set of possible finger shapes, each analytic at the nose and occupying a different fraction of the channel width. In the limit in which the kinetic undercooling parameter vanishes, the fraction for each family approaches 1 /2 , suggesting that this "selection" of 1 /2 by kinetic undercooling is qualitatively similar to the well-known analog with surface tension. We treat the numerical problem of computing these Saffman-Taylor fingers with kinetic undercooling, which turns out to be more subtle than the analog with surface tension, since kinetic undercooling permits finger shapes which are corner-free but not analytic. We provide numerical evidence for the selection mechanism by setting up a problem with both kinetic undercooling and surface tension and numerically taking the limit that the surface tension vanishes.

  10. Multifluid MHD Simulation of Saturn's Interchange Fingers

    NASA Astrophysics Data System (ADS)

    Lucas, N.; Rajendar, A.; Paty, C. S.

    2014-12-01

    Saturn's magnetosphere exhibits rich dynamics that have only become apparent through recent missions such as the Cassini mission currently in progress. Examining local time variations in the magnetosphere has shown some interesting phenomena. One of the primary expressions of the dynamics we observe in Saturn's magnetosphere are plasma interchange fingers. These fingers carry hot plasma from the outer magnetosphere to the inner magnetosphere to balance magnetic flux lost due to outward radial transport of cold dense plasma sourced from the neutral cloud. This process leads to a mixing of hot and cold plasma throughout the magnetosphere. Understanding how mass interchange fingers form and quantifying how the plasma they contain is heated and transported will be important for understanding other dynamic processes occurring in the magnetosphere. In this study, we will be using our existing multifluid simulation of Saturn's magnetosphere in combination with data from the Cassini mission in order to investigate the formation of plasma interchange fingers and their dynamics. Our results will be compared with observations as well as previous modeling studies of Saturn's interchange fingers.

  11. Developing and validating advanced divertor solutions on DIII-D for next-step fusion devices

    DOE PAGES

    Guo, H. Y.; Hill, D. N.; Leonard, A. W.; Allen, S. L.; Stangeby, P. C.; Thomas, D.; Unterberg, E. A.; Abrams, T.; Boedo, J.; Briesemeister, A. R.; et al

    2016-09-14

    A major challenge facing the design and operation of next-step high-power steady-state fusion devices is to develop a viable divertor solution with order-of-magnitude increases in power handling capability relative to present experience, while having acceptable divertor target plate erosion and being compatible with maintaining good core plasma confinement. A new initiative has been launched on DIII-D to develop the scientific basis for design, installation, and operation of an advanced divertor to evaluate boundary plasma solutions applicable to next step fusion experiments beyond ITER. Developing the scientific basis for fusion reactor divertor solutions must necessarily follow three lines of research, whichmore » we plan to pursue in DIII-D: (1) Advance scientific understanding and predictive capability through development and comparison between state-of-the art computational models and enhanced measurements using targeted parametric scans; (2) Develop and validate key divertor design concepts and codes through innovative variations in physical structure and magnetic geometry; (3) Assess candidate materials, determining the implications for core plasma operation and control, and develop mitigation techniques for any deleterious effects, incorporating development of plasma-material interaction models. These efforts will lead to design, installation, and evaluation of an advanced divertor for DIII-D to enable highly dissipative divertor operation at core density (n e/n GW), neutral fueling and impurity influx most compatible with high performance plasma scenarios and reactor relevant plasma facing components (PFCs). In conclusion, this paper highlights the current progress and near-term strategies of boundary/PMI research on DIII-D.« less

  12. Developing and validating advanced divertor solutions on DIII-D for next-step fusion devices

    NASA Astrophysics Data System (ADS)

    Guo, H. Y.; Hill, D. N.; Leonard, A. W.; Allen, S. L.; Stangeby, P. C.; Thomas, D.; Unterberg, E. A.; Abrams, T.; Boedo, J.; Briesemeister, A. R.; Buchenauer, D.; Bykov, I.; Canik, J. M.; Chrobak, C.; Covele, B.; Ding, R.; Doerner, R.; Donovan, D.; Du, H.; Elder, D.; Eldon, D.; Lasa, A.; Groth, M.; Guterl, J.; Jarvinen, A.; Hinson, E.; Kolemen, E.; Lasnier, C. J.; Lore, J.; Makowski, M. A.; McLean, A.; Meyer, B.; Moser, A. L.; Nygren, R.; Owen, L.; Petrie, T. W.; Porter, G. D.; Rognlien, T. D.; Rudakov, D.; Sang, C. F.; Samuell, C.; Si, H.; Schmitz, O.; Sontag, A.; Soukhanovskii, V.; Wampler, W.; Wang, H.; Watkins, J. G.

    2016-12-01

    A major challenge facing the design and operation of next-step high-power steady-state fusion devices is to develop a viable divertor solution with order-of-magnitude increases in power handling capability relative to present experience, while having acceptable divertor target plate erosion and being compatible with maintaining good core plasma confinement. A new initiative has been launched on DIII-D to develop the scientific basis for design, installation, and operation of an advanced divertor to evaluate boundary plasma solutions applicable to next step fusion experiments beyond ITER. Developing the scientific basis for fusion reactor divertor solutions must necessarily follow three lines of research, which we plan to pursue in DIII-D: (1) Advance scientific understanding and predictive capability through development and comparison between state-of-the art computational models and enhanced measurements using targeted parametric scans; (2) Develop and validate key divertor design concepts and codes through innovative variations in physical structure and magnetic geometry; (3) Assess candidate materials, determining the implications for core plasma operation and control, and develop mitigation techniques for any deleterious effects, incorporating development of plasma-material interaction models. These efforts will lead to design, installation, and evaluation of an advanced divertor for DIII-D to enable highly dissipative divertor operation at core density (n e/n GW), neutral fueling and impurity influx most compatible with high performance plasma scenarios and reactor relevant plasma facing components (PFCs). This paper highlights the current progress and near-term strategies of boundary/PMI research on DIII-D.

  13. Perceiving fingers in single-digit arithmetic problems

    PubMed Central

    Berteletti, Ilaria; Booth, James R.

    2015-01-01

    In this study, we investigate in children the neural underpinnings of finger representation and finger movement involved in single-digit arithmetic problems. Evidence suggests that finger representation and finger-based strategies play an important role in learning and understanding arithmetic. Because different operations rely on different networks, we compared activation for subtraction and multiplication problems in independently localized finger somatosensory and motor areas and tested whether activation was related to skill. Brain activations from children between 8 and 13 years of age revealed that only subtraction problems significantly activated finger motor areas, suggesting reliance on finger-based strategies. In addition, larger subtraction problems yielded greater somatosensory activation than smaller problems, suggesting a greater reliance on finger representation for larger numerical values. Interestingly, better performance in subtraction problems was associated with lower activation in the finger somatosensory area. Our results support the importance of fine-grained finger representation in arithmetical skill and are the first neurological evidence for a functional role of the somatosensory finger area in proficient arithmetical problem solving, in particular for those problems requiring quantity manipulation. From an educational perspective, these results encourage investigating whether different finger-based strategies facilitate arithmetical understanding and encourage educational practices aiming at integrating finger representation and finger-based strategies as a tool for instilling stronger numerical sense. PMID:25852582

  14. Lithium-Metal Infused Trenches: Progress toward a Divertor Solution

    NASA Astrophysics Data System (ADS)

    Ruzic, D. N.; Fiflis, P.; Christenson, M.; Szott, M.; Xu, W.; Jung, S.; Morgan, T. W.; Kalathiparambil, K.

    2014-10-01

    The application of liquid metal, especially liquid lithium, as a plasma facing component (PFC) has the capacity to offer a strong alternative to solid PFCs by reducing damage concerns and enhancing plasma performance. The Liquid-Metal Infused Trenches (LiMIT) concept is a liquid metal divertor alternative which employs thermoelectric current from either plasma or external heating in tandem with the toroidal field to self-propel liquid lithium through a series of trenches. LiMIT has been tested in several devices, namely HT-7, the UIUC SLiDE and TELS facilities and Magnum PSI at heat fluxes of up to 3 MW/m-2. Results of these experiments, including velocity and temperature measurements, power handling considerations, and preliminary vapor shielding results will be discussed, focusing on the 117 shots performed at Magnum scanning magnetic fields and heat fluxes up to ~ 0.3 T and 3 MW/m-2. Concerns over tritium retention and MHD droplet ejection will additionally be addressed. LiMIT has also been proposed to function as a limiter on the EAST moveable limiter arm and tests have been performed with a prototype module inclined at various angles.

  15. Solid-Liquid Lithium Divertor Experiment: SLiDE

    NASA Astrophysics Data System (ADS)

    Jaworski, Michael; Ruzic, David

    2006-10-01

    Liquid lithium has been proposed as a material for the first wall and divertor/limiter of a fusion device. One objection raised against the use of liquid lithium is the high vapor pressure at modest temperature increases. Recent experiments on the CDX-U device show however, that lithium absorbs a surface heat flux of greater than 40 MW/m^2 with negligible evaporation. Observation of a focused electron beam hitting solid lithium in the CDX-U lithium tray saw melting of a large section of the tray. Macroscopic liquid flows were observed which redistributed the incident power. Surface tension effects caused by temperature gradients have been proposed as a mechanism for this convection. These flows were insensitive to MHD effects in fields up to 600G [1]. This paper presents a design of an experiment which will diagnose the flows induced by an intense heat flux onto a lithium pool and measure the maximum heat flux lithium can absorb in an incident magnetic field. A number of diagnostics are considered and evaluated with the goal of being minimally invasive to the induced flows. These results are the first step in the creation of an experimental facility to study the heat transfer capabilities of free-surface liquid lithium at the University of Illinois. [1] Majeski, et al., Final results from the CDX-U lithium program, Presentation at APS-DPP05, Denver, Colorado. 2005.

  16. Calculations of neutral transport in the PDX divertor

    NASA Astrophysics Data System (ADS)

    Heifetz, D. B.; Petravic, M.; Post, D. E.; Lieberson-Heifetz, S.

    1984-05-01

    Neutral particle transport during a typical beam-heated PDX diverted discharge was modeled using the multidimensional code DEGAS. Plasma parameters were taken from probe measurements, and were assumed not to change during the calculations. A realistic plasma/divertor geometry was included in the model, along with a simple particle recycling scheme. Calculated results were compared with the experimentally measured neutral pressures. Without any pumping in the device, the computed pressures were found to be higher than those measured by a factor of approximately two. Introducing a simple pumping model for wall absorption, wherein 10% of the absorbed neutral particles were assumed not to desorb, reduced the calculated pressures to about the measured values. However the pressure was observed to monotonically increase during the discharge, whereas the model results peaked in mid-discharge. One possible explanation of the disagreement is that the saturation of the device walls increases during the discharge, so that the fraction of particles pumped decreases with time. Reduction of the permanently absorbed fraction from 10 to 4% during the course of the discharge caused the calculated pressure to monotonically increase.

  17. Response of NSTX Liquid Lithium divertor to High Heat Loads

    SciTech Connect

    Abrams, Tyler; Kallman, J; Kaitaa, R; Foley, E L; Grayd, T K; Kugel, H; Levinton, F; McLean, A G; Skinner, C H

    2012-07-18

    Samples of the NSTX Liquid Lithium Divertor (LLD) with and without an evaporative Li coating were directly exposed to a neutral beam ex-situ at a power of ~1.5 MW/m2 for 1-3 seconds. Measurements of front face and bulk sample temperature were obtained. Predictions of temperature evolution were derived from a 1D heat flux model. No macroscopic damage occurred when the "bare" sample was exposed to the beam but microscopic changes to the surface were observed. The Li-coated sample developed a lithium hydroxide (LiOH) coating, which did not change even when the front face temperature exceeded the pure Li melting point. These results are consistent with the lack of damage to the LLD surface and imply that heating alone may not expose pure liquid Li if the melting point of surface impurities is not exceeded. This suggests that flow and heat are needed for future PFCs requiring a liquid Li surface. __________________________________________________

  18. Fingering instabilities of a reactive micellar interface

    NASA Astrophysics Data System (ADS)

    Podgorski, Thomas; Sostarecz, Michael C.; Zorman, Sylvain; Belmonte, Andrew

    2007-07-01

    We present an experimental study of the fingering patterns in a Hele-Shaw cell occurring when a gel-like material forms at the interface between aqueous solutions of a cationic surfactant (cetyltrimethylammonium bromide) and an organic salt (salicylic acid), two solutions known to form a highly elastic wormlike micellar fluid when mixed homogeneously. A variety of fingering instabilities are observed, depending on the velocity of the front (the injection rate), and on which fluid is injected into which. We have found a regime of nonconfined stationary or wavy fingers for which width selection seems to occur without the presence of bounding walls, unlike the Saffman-Taylor experiment. Qualitatively, some of our observations share common mechanisms with instabilities of cooling lava flows or growing biofilms.

  19. The optimum finger spacing in human swimming.

    PubMed

    Minetti, Alberto E; Machtsiras, Georgios; Masters, Jonathan C

    2009-09-18

    Competitive swimmers spread fingers during the propulsive stroke. Due to the inherent inefficiency of human swimming, the question is: does this strategy enhance performance or is it just a more comfortable hand posture? Here we show, through computational fluid dynamics (CFD) of a 3D model of the hand, that an optimal finger spacing (12 degrees , roughly corresponding to the resting hand posture) increases the drag coefficient (+8.8%), which is 'functionally equivalent' to a greater hand palm area, thus a lower stroke frequency can produce the same thrust, with benefits to muscle, hydraulic and propulsive efficiencies. CFD, through flow visualization, provides an explanation for the increased drag associated with the optimum finger spacing. PMID:19651409

  20. Finger millet [Eleusine coracana (L.) Gaertn].

    PubMed

    Ceasar, Stanislaus Antony; Ignacimuthu, Savarimuthu

    2015-01-01

    Millets are the primary food source for millions of people in tropical regions of the world supplying mineral nutrition and protein. In this chapter, we describe an optimized protocol for the Agrobacterium-mediated transformation of finger millet variety GPU 45. Agrobacterium strain LBA4404 harboring plasmid pCAMBIA1301 which contains hygromycin phosphotransferase (hph) as selectable marker gene and β-glucuronidase (GUS) as reporter gene has been used. This protocol utilizes the shoot apex explants for the somatic embryogenesis and regeneration of finger millet after the transformation by Agrobacterium. Desiccation of explants during cocultivation helps for the better recovery of transgenic plants. This protocol is very useful for the efficient production of transgenic plants in finger millet through Agrobacterium-mediated transformation. PMID:25300836

  1. The PHD Finger: A Versatile Epigenome Reader

    PubMed Central

    Sanchez, Roberto; Zhou, Ming-Ming

    2011-01-01

    PHD (plant homeodomain) zinc fingers are structurally conserved modules found in proteins that modify chromatin as well as mediate molecular interactions in gene transcription. The original discovery of their role in gene transcription is attributed to the recognition of lysine-methylated histone H3. Recent studies show that PHD fingers have a sophisticated histone sequence reading capacity that is modulated by the interplay between different histone modifications. These studies underscore the functional versatility of PHD fingers as epigenome readers that control gene expression through molecular recruitment of multi-protein complexes of chromatin regulators and transcription factors. Moreover, they reinforce the concept that evolutionary changes in amino acids surrounding ligand binding sites on a conserved structural fold impart great functional diversity upon this family of proteins. PMID:21514168

  2. Finger recognition and gesture imitation in Gerstmann's syndrome.

    PubMed

    Moro, V; Pernigo, S; Urgesi, C; Zapparoli, P; Aglioti, S M

    2008-01-01

    We report the association between finger agnosia and gesture imitation deficits in a right-handed, right-hemisphere damaged patient with Gerstmann's syndrome (GS), a neuropsychological syndrome characterized by finger and toe agnosia, left-right disorientation and dyscalculia. No language deficits were found. The patient showed a gestural imitation deficit that specifically involved finger movements and postures. The association between finger recognition and imitation deficits suggests that both static and dynamic aspects of finger representations are impaired in GS. We suggest that GS is a disorder of body representation that involves hands and fingers, that is, the non-facial body parts most involved in social interactions.

  3. Geometrical Effects in Plasma Stability and Dynamics of Coherent Structures in the Divertor

    SciTech Connect

    Ryutov, D D; Cohen, R H

    2007-05-16

    Plasma dynamics in the divertor region is strongly affected by a variety of phenomena associated with the magnetic field geometry and the shape of the divertor plates. One of the most universal effects is the squeezing of a normal cross-section of a thin magnetic flux-tube on its way from the divertor plate to the main SOL. It leads to decoupling of the most unstable perturbations in the divertor legs from those in the main SOL. For perturbations on either side of the X-point, this effect can be cast as a boundary condition at some 'control surface' situated near the X-point. We discuss several boundary conditions proposed thus far and assess the influence of the magnetic field geometry on them. Another set of geometrical effects is related to the transformation of a flux-tube that occurs when it is displaced in such a way that its central magnetic field line coincides with some other field line, and the magnetic field is not perturbed. These flute-like displacements are of a particular interest for the low-beta edge plasmas. It turns out that this transformation may also lead to a considerable deformation of a flux-tube cross-section; in addition, the distance between plasma particles occupying the flux-tube may change significantly even if there is no parallel plasma motion. We present expressions describing aforementioned transformations for the general tokamak geometry and simplify them for the divertor region (using the proximity of the X-point). We also discuss the effects associated with the shape of the plasma-limiting surfaces, both those designed to intercept the plasma (like divertor plates and limiters) and those that can be hit in some 'abnormal' events, e.g., in the course of a radial motion of an isolated plasma filament. The orientation of the limiting surface with respect to the magnetic field affects the plasma dynamics via the sheath boundary conditions. One can enhance or suppress plasma instabilities in the divertor legs by tilting the divertor

  4. Reciprocating and fixed probe measurements of density and temperature in the DIII-D divertor

    NASA Astrophysics Data System (ADS)

    Watkins, J. G.; Moyer, R. A.; Cuthbertson, J. W.; Buchenauer, D. A.; Carlstrom, T. N.; Hill, D. N.; Ulrickson, M.

    1997-02-01

    This paper describes divertor density and temperature measurements using both a new reciprocating Langmuir probe (XPT-RCP) which plunges vertically above the divertor floor up to the X-point height and swept, single, Langmuir probes fixed horizontally across the divertor floor. These types of measurements are important for testing models of the SOL and divertor which then are used to determine engineering design criteria for plasma facing components in reactor size tokamaks. The 6 mm diameter fixed single probes (19 domed and 2 flat at radially equivalent locations) are incorporated into the lower divertor floor at 19 radial locations and swept at 250 Hz. These probes are critical for determining plasma detachment from the floor during operation with high density, highly radiating divertors. By sweeping the divertor strike point across the fixed probes, different regions of the target plate incident flux profile can be sampled and a high resolution spatial profile can be obtained from each probe tip as the strike point moves past. The X-point reciprocating probe (XPT-RCP) provides ne and Te profiles with high spatial (2 mm) and temporal (0.5 ms) resolution from the target plate to the X-point along a single vertical chord at the same radial location as a fixed probe tip at a different azimuthal location. The probe ne and Te are compared to the divertor Thomson scattering (DTS) ne and Te (eight vertical points at 20 Hz, RThomson = RX- point- rcp). Recent observations have also shown divertor densities from 3 × 10 19to 4 × 10 20m-3 near the target plate with the highest densities observed with D 2 gas puffing. Electron temperature is typically of the order of 15-25 eV at the target rising to about 70 eV near the X-point. Lower temperature, higher density plasmas are observed along the inner leg. Generally good agreement among the XPT-RCP, the fixed floor probes, and the DTS is observed. Differences between these diagnostic measurements will also be discussed with

  5. Fingering instability in combustion: an extended view.

    PubMed

    Zik, O; Moses, E

    1999-07-01

    We detail the experimental situation concerning the fingering instability that occurs when a solid fuel is forced to burn against a horizontal oxidizing wind. The instability appears when the Rayleigh number for convection is below criticality. The focus is on the developed fingering state. We present direct measurements of the depletion of oxygen by the front as well as new results that connect heat losses to the characteristic scale of the instability. In addition, we detail the experimental system, elaborate (qualitatively and quantitatively) on the results that were previously presented, and discuss new observations. We also show that the same phenomenological model applies to electrochemical deposition.

  6. Thermoregulatory control of finger blood flow

    NASA Technical Reports Server (NTRS)

    Wenger, C. B.; Roberts, M. F.; Nadel, E. R.; Stolwijk, J. A. J.

    1975-01-01

    In the present experiment, exercise was used to vary internal temperature and ambient air heat control was used to vary skin temperature. Finger temperature was fixed at about 35.7 C. Esophageal temperature was measured with a thermocouple at the level of the left atrium, and mean skin temperature was calculated from a weighted mean of thermocouple temperatures at different skin sites. Finger blood flow was measured by electrocapacitance plethysmography. An equation in these quantities is given which accounts for the data garnered.

  7. Conceptual design of divertor and first wall for DEMO-FNS

    NASA Astrophysics Data System (ADS)

    Sergeev, V. Yu.; Kuteev, B. V.; Bykov, A. S.; Gervash, A. A.; Glazunov, D. A.; Goncharov, P. R.; Dnestrovskij, A. Yu.; Khayrutdinov, R. R.; Klishchenko, A. V.; Lukash, V. E.; Mazul, I. V.; Molchanov, P. A.; Petrov, V. S.; Rozhansky, V. A.; Shpanskiy, Yu. S.; Sivak, A. B.; Skokov, V. G.; Spitsyn, A. V.

    2015-11-01

    Key issues of design of the divertor and the first wall of DEMO-FNS are presented. A double null closed magnetic configuration was chosen with long external legs and V-shaped corners. The divertor employs a cassette design similar to that of ITER. Water-cooled first wall of the tokamak is made of Be tiles and CuCrZr-stainless steel shells. Lithium injection and circulation technologies are foreseen for protection of plasma facing components. Simulations of thermal loads onto the first wall and divertor plates suggest a possibility to distribute heat loads making them less than 10 MW m-2. Evaluations of sputtering and evaporation of plasma-facing materials suggest that lithium may protect the first wall. To prevent Be erosion at the outer divertor plates either the full detached divertor operation or arrangement of the renewal lithium flow on targets should be implemented. Test bed experiments on the Tsefey-M facility with the first wall mockup coated by Ве tiles and cooled by water are presented. The temperature of the surface of tiles reached 280-300 °С at 5 MW m-2 and 600-650 °С at 10.5 MW m-2. The mockup successfully withstood 1000 cycles with the lower thermal loading and 100 cycles with higher thermal loading.

  8. Intermittent Divertor Filaments in the National Spherical Torus Experiment and Their Relation to Midplane Blobs

    SciTech Connect

    R.J. Maqueda, D.P. Stotler and the NSTX Team.

    2010-05-19

    While intermittent filamentary structures, also known as blobs, are routinely seen in the low-field-side scrape-off layer of the National Spherical Torus Experiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557), fine structured filaments are also seen on the lower divertor target plates of NSTX. These filaments, not associated with edge localized modes, correspond to the interaction of the turbulent blobs seen near the midplane with the divertor plasma facing components. The fluctuation level of the neutral lithium light observed at the divertor, and the skewness and kurtosis of its probability distribution function, is similar to that of midplane blobs seen in Dα; e.g. increasing with increasing radii outside the outer strike point (OSP) (separatrix). In addition, their toroidal and radial movement agrees with the typical movement of midplane blobs. Furthermore, with the appropriate magnetic topology, i.e. mapping between the portion of the target plates being observed into the field of view of the midplane gas puff imaging diagnostic, very good correlation is observed between the blobs and the divertor filaments. The correlation between divertor plate filaments and midplane blobs is lost close to the OSP. This latter observation is consistent with the existence of ‘magnetic shear disconnection’ due to the lower X-point, as proposed by Cohen and Ryutov (1997 Nucl. Fusion 37 621).

  9. ADX: A high Power Density, Advanced RF-Driven Divertor Test Tokamak for PMI studies

    NASA Astrophysics Data System (ADS)

    Whyte, Dennis; ADX Team

    2015-11-01

    The MIT PSFC and collaborators are proposing an advanced divertor experiment, ADX; a divertor test tokamak dedicated to address critical gaps in plasma-material interactions (PMI) science, and the world fusion research program, on the pathway to FNSF/DEMO. Basic ADX design features are motivated and discussed. In order to assess the widest range of advanced divertor concepts, a large fraction (>50%) of the toroidal field volume is purpose-built with innovative magnetic topology control and flexibility for assessing different surfaces, including liquids. ADX features high B-field (>6 Tesla) and high global power density (P/S ~ 1.5 MW/m2) in order to access the full range of parallel heat flux and divertor plasma pressures foreseen for reactors, while simultaneously assessing the effect of highly dissipative divertors on core plasma/pedestal. Various options for efficiently achieving high field are being assessed including the use of Alcator technology (cryogenic cooled copper) and high-temperature superconductors. The experimental platform would also explore advanced lower hybrid current drive and ion-cyclotron range of frequency actuators located at the high-field side; a location which is predicted to greatly reduce the PMI effects on the launcher while minimally perturbing the core plasma. The synergistic effects of high-field launchers with high total B on current and flow drive can thus be studied in reactor-relevant boundary plasmas.

  10. Power exhaust in all geometric variations of the snowflake divertor on TCV

    NASA Astrophysics Data System (ADS)

    Vijvers, Wouter; Canal, Gustavo; Duval, Basil; Labit, Benoit; Reimerdes, Holger; Coda, Stefano; Lunt, Tilmann; Morgan, Thomas; de Temmerman, Greg

    2013-10-01

    The snowflake (SF) divertor is recognized as a potential exhaust solution for large-scale, high-performance tokamaks. TCV has advanced to a detailed study of the transport through the SF's scrape-off layer (SOL), null region and divertor legs to determine the optimal geometry and quantify parallel and cross-field transport. Experimental SF plasmas have two closely spaced x-points, leading to two additional strike points (SPs) and a larger region of low poloidal field than in a conventional divertor. The relative x-point positions determine the divertor geometry and hence the exhaust properties. The results show that if parallel transport is dominant, either the HFS or LFS SOL power can be distributed to two SPs, with the power ratio depending on the SOL width, inter-x-point distance (D) and geometrical divertor asymmetry. Cross-field transport allows power to reach SPs in the private flux region. Experiments show significant power reaching such SPs already at large D, particularly during ELMs, enabling a 2-3x reduction in flux to the main SPs. As EMC3-Eirene simulations predict much smaller SP powers, additional transport mechanisms beyond perpendicular diffusion are considered. The SF's beneficial magnetic properties are shown to be enhanced in reactor-size devices.

  11. Impact of Resonant Magnetic Perturbation Fields on NSTX-U Advanced Divertor Topologies

    NASA Astrophysics Data System (ADS)

    Waters, Ian; Frerichs, Heinke; Schmitz, Oliver; Ahn, Joon-Wook; Canal, Gustavo; Evans, Todd; Soukhanovskii, Vlad

    2015-11-01

    Explorations are under way to optimize the magnetic topology in the plasma edge of NSTX-U with the goal of improving neutral and impurity fueling and exhaust. The use of magnetic perturbation fields is being considered to spread heat and particle fluxes in the divertor, adjust plasma refueling, control impurity transport, and improve coupling to the exhaust systems. Also, advanced divertor configurations are being considered to improve peak heat loads on divertors. An assessment is made of the topologies of a number of representative NSTX-U advanced divertor configurations: lower single null, exact snowflake, and snowflake minus. Wall to wall magnetic connection lengths for each configuration are assessed in both their perturbed and axisymmetric configurations with perturbation coil currents of 1kA and 3kA. The magnetic perturbations yield complex strike patterns on divertor elements that are expected to be resolvable experimentally. The EMC3-EIRENE fluid plasma and kinetic neutral transport code will be used to study neutral and impurity transport and exhaust in these topologies. This work was funded in part by the Department of Energy under grant DE-SC0012315 and by startup funds of the Department of Engineering Physics at the University of Wisconsin-Madison.

  12. Scaling and transport analysis of divertor conditions on the Alcator C-Mod tokamak

    NASA Astrophysics Data System (ADS)

    LaBombard, B.; Goetz, J.; Kurz, C.; Jablonski, D.; Lipschultz, B.; McCracken, G.; Niemczewski, A.; Boivin, R. L.; Bombarda, F.; Christensen, C.; Fairfax, S.; Fiore, C.; Garnier, D.; Graf, M.; Golovato, S.; Granetz, R.; Greenwald, M.; Horne, S.; Hubbard, A.; Hutchinson, I.; Irby, J.; Kesner, J.; Luke, T.; Marmar, E.; May, M.; O'Shea, P.; Porkolab, M.; Reardon, J.; Rice, J.; Schachter, J.; Snipes, J.; Stek, P.; Takase, Y.; Terry, J.; Tinios, G.; Watterson, R.; Welch, B.; Wolfe, S.

    1995-06-01

    Detailed measurements and transport analysis of divertor conditions in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are presented for a range of line-averaged densities, 0.7divertor, and detached divertor, which can coexist in the same discharge. Local cross-field pressure gradients are found to scale simply with a local electron temperature. This scaling is consistent with classical electron parallel conduction being balanced by anomalous cross-field transport (χ⊥˜0.2 m2 s-1) proportional to the local pressure gradient. A 60%-80% of divertor power is radiated in attached discharges, approaching 100% in detached discharges. Detachment occurs when the heat flux to the plate is low and the plasma pressure is high (Te˜5 eV). High neutral pressures in the divertor are nearly always present (1-20 mTorr), sufficient to remove parallel momentum via ion-neutral collisions.

  13. Engineering design of cryocondensation pumps for the DIII-D Radiative Divertor Program

    SciTech Connect

    Bozek, A.S.; Baxi, C.B.; Del Bene, J.V.; Laughon, G.J.; Reis, E.E.; Shatoff, H.D.; Smith, J.P.

    1995-10-01

    A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing program was completed to test the change in geometry of the pump feed lines with respect to helium flow stability. The results were compared to the helium thermal and fluid analyses to verify predicted flow regimes and flow stability.

  14. Sputtering and Reflection Data for Mixed Tungsten/Beryllium Layers Under Typical FIRE Divertor Fluxes

    NASA Astrophysics Data System (ADS)

    Ruzic, D. N.; Nieto, M.; Alman, D. A.; Brooks, J. N.

    2001-10-01

    Computer modeling has been done as part of the Fusion Ignition Research Experiment (FIRE) design study. The current focus is on beryllium/tungsten mixed-material erosion. The FIRE design calls for a beryllium first wall and tungsten divertors. Beryllium can be sputtered from the first wall and transported to the divertor, forming a Be/W mixture on the divertor. The beryllium sputtering from the first wall is obtained from fluxes calculated by the DEGAS2 neutral transport code. Subsequent transport to the divertor is calculated by the REDEP code. VFTRIM-3D, a variant of the TRIM-SP binary-collision code, is used to investigate the sputtering properties of the Be/W divertor. Finally, WBC can compute beryllium and tungsten erosion and core plasma contamination using the sputtering and reflection coefficients obtained with VFTRIM-3D. In the present work, the VFTRIM-3D code was run on a W/Be surface with the Be content varied from 0 to 100 atomic percent. Deuterium and tritium (ions and neutrals), oxygen, beryllium from the first wall, and tungsten being redeposited are all incident on this mixed W/Be layer. Data on reflection and sputtering coefficients as a function of beryllium content in the bombarded surface will be presented.

  15. Interaction of finger enslaving and error compensation in multiple finger force production

    PubMed Central

    Martin, Joel R.; Latash, Mark L.; Zatsiorsky, Vladimir M.

    2009-01-01

    Previous studies have documented two patterns of finger interaction during multi-finger pressing tasks, enslaving and error compensation, which do not agree with each other. Enslaving is characterized by positive correlation between instructed (master) and non-instructed (slave) finger(s) while error compensation can be described as a pattern of negative correlation between master and slave fingers. We hypothesize that pattern of finger interaction, enslaving or compensation, depends on the initial force level and the magnitude of the targeted force change. Subjects were instructed to press with four fingers (I - index, M - middle, R - ring, and L - little) from a specified initial force to a target forces following a ramp target line. Force-force relations between master and each of three slave fingers were analyzed during the ramp phase of trials by calculating correlation coefficients within each master-slave pair and then 2-factor ANOVA was performed to determine effect of initial force and force increase on the correlation coefficients. It was found that, as initial force increased, the value of the correlation coefficient decreased and in some cases became negative, i.e. the enslaving transformed into error compensation. Force increase magnitude had a smaller effect on the correlation coefficients. The observations support the hypothesis that the pattern of inter-finger interaction—enslaving or compensation—depends on the initial force level and, to a smaller degree, on the targeted magnitude of the force increase. They suggest that the controller views tasks with higher steady-state forces and smaller force changes as implying a requirement to avoid large changes in the total force. PMID:18985331

  16. Finger joint force minimization in pianists using optimization techniques.

    PubMed

    Harding, D C; Brandt, K D; Hillberry, B M

    1993-12-01

    A numerical optimization procedure was used to determine finger positions that minimize and maximize finger tendon and joint force objective functions during piano play. A biomechanical finger model for sagittal plane motion, based on finger anatomy, was used to investigate finger tendon tensions and joint reaction forces for finger positions used in playing the piano. For commonly used piano key strike positions, flexor and intrinsic muscle tendon tensions ranged from 0.7 to 3.2 times the fingertip key strike force, while resultant inter-joint compressive forces ranged from 2 to 7 times the magnitude of the fingertip force. In general, use of a curved finger position, with a large metacarpophalangeal joint flexion angle and a small proximal interphalangeal joint flexion angle, reduces flexor tendon tension and resultant finger joint force.

  17. Development of divertor plate with CFCs bonded onto DSCu cooling tube for fusion reactor application

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Suzuki, T.; Araki, M.; Nakamura, K.; Akiba, M.

    1998-10-01

    This paper presents the high heat flux experiment of divertor mock-ups with CFC-Cu duplex structure. A plasma-facing component (PFC), which is served as a protection wall against heat and particle loads from fusion plasma, is one of the critical components of next fusion devices such as ITER. A divertor plate which is one of the PFCs must be capable of withstanding cyclic heat load of 5-20 MW/m 2 in ITER. To investigate the thermal fatigue behavior, a thermal cycling experiment was conducted in Particle Beam Engineering Facility. As a result, the divertor mock-up with a dispersion strengthened copper cooling tube could withstand a heat flux of 20 MW/m 2 for 1000 cycles. On the other hand, the mock-up with an oxygen-free-high conductivity copper cooling tube showed a water leakage at about 400 cycles due to thermal fatigue cracking.

  18. Exposures of tungsten nanostructures to divertor plasmas in DIII-D

    NASA Astrophysics Data System (ADS)

    Rudakov, D. L.; Wong, C. P. C.; Doerner, R. P.; Wright, G. M.; Abrams, T.; Baldwin, M. J.; Boedo, J. A.; Briesemeister, A. R.; Chrobak, C. P.; Guo, H. Y.; Hollmann, E. M.; McLean, A. G.; Fenstermacher, M. E.; Lasnier, C. J.; Leonard, A. W.; Moyer, R. A.; Pace, D. C.; Thomas, D. M.; Watkins, J. G.

    2016-02-01

    Tungsten nanostructures (W-fuzz) prepared in the PISCES-A linear device have been found to survive direct exposure to divertor plasmas in DIII-D. W-fuzz was exposed in the lower divertor of DIII-D using the divertor material evaluation system. Two samples were exposed in lower single null (LSN) deuterium H-mode plasmas. The first sample was exposed in three discharges terminated by vertical displacement event disruptions, and the second in two discharges near the lowered X-point. More recently, three samples were exposed near the lower outer strike point in predominantly helium H-mode LSN plasmas. In all cases, the W-fuzz survived plasma exposure with little obvious damage except in the areas where unipolar arcing occurred. Arcing is effective in W-fuzz removal, and it appears that surfaces covered with W-fuzz can be more prone to arcing than smooth W surfaces.

  19. Simulation of Turbulence in the Divertor Region of Tokamak Edge Plasma

    SciTech Connect

    Umansky, M; Rognlien, T; Xu, X

    2004-10-04

    Results are presented for turbulence simulations with the fluid edge turbulence code BOUT [1]. The present study is focused on turbulence in the divertor leg region and on the role of the X-point in the structure of turbulence. Results of the present calculations indicate that the ballooning effects are important for the divertor fluctuations. The X-point shear leads to weak correlation of turbulence across the X-point regions, in particular for large toroidal wavenumber. For the saturated amplitudes of the divertor region turbulence it is found that amplitudes of density fluctuations are roughly proportional to the local density of the background plasma. The amplitudes of electron temperature and electric potential fluctuations are roughly proportional to the local electron temperature of the background plasma.

  20. Investigation of SOL parameters and divertor particle flux from electric probe measurements in KSTAR

    NASA Astrophysics Data System (ADS)

    Bak, J. G.; Kim, H. S.; Bae, M. K.; Juhn, J. W.; Seo, D. C.; Bang, E. N.; Shim, S. B.; Chung, K. S.; Lee, H. J.; Hong, S. H.

    2015-08-01

    The upstream scrape-off layer (SOL) profiles and downstream particle fluxes are measured with a fast reciprocating Langmuir probe assembly (FRLPA) at the outboard mid-plane and a fixed edge Langmuir probe array (ELPA) at divertor region, respectively in the KSTAR. It is found that the SOL has a two-layer structure in the outboard wall-limited (OWL) ohmic and L-mode: a near SOL (∼5 mm zone) with a narrow feature and a far SOL with a broader profile. The near SOL width evaluated from the SOL profiles in the OWL plasmas is comparable to the scaling for the L-mode divertor plasmas in the JET and AUG. In the SOL profiles and the divertor particle flux profile during the ELMy H-modes, the characteristic e-folding lengths of electron temperature, plasma density and particle flux during an ELM phase are about two times larger than ones at the inter ELM.

  1. Co-deposited layers in the divertor region of JET-ILW

    NASA Astrophysics Data System (ADS)

    Petersson, P.; Rubel, M.; Esser, H. G.; Likonen, J.; Koivuranta, S.; Widdowson, A.

    2015-08-01

    Tungsten-coated carbon tiles from a poloidal cross-section of the divertor and several types of erosion-deposition probes from the shadowed areas in the divertor were studied using heavy ion elastic recoil detection to obtain quantitative and depth-resolved deposition patterns. Deuterium, beryllium, carbon, nitrogen and oxygen along with tungsten and Inconel components are the main species detected in the studied surface region. The top of Tile 1 in the inner divertor is the main deposition area where the greatest amounts of deposited species are measured. Beryllium and tungsten-containing deposits on the probes (test mirrors and quartz microbalance) indicate that both low-Z and high-Z metals are transported to remote areas. Deposition of nitrogen-15 tracer used for edge cooling only at the end of experimental campaigns in 2012 was also detected giving evidence that nitrogen is effectively retained in wall components.

  2. Divertor with a third-order null of the poloidal field

    SciTech Connect

    Ryutov, D. D.; Umansky, M. V.

    2013-09-15

    A concept and preliminary feasibility analysis of a divertor with the third-order poloidal field null is presented. The third-order null is the point where not only the field itself but also its first and second spatial derivatives are zero. In this case, the separatrix near the null-point has eight branches, and the number of strike-points increases from 2 (as in the standard divertor) to six. It is shown that this magnetic configuration can be created by a proper adjustment of the currents in a set of three divertor coils. If the currents are somewhat different from the required values, the configuration becomes that of three closely spaced first-order nulls. Analytic approach, suitable for a quick orientation in the problem, is used. Potential advantages and disadvantages of this configuration are briefly discussed.

  3. Flute instability in the tandem mirror with the divertor/dipole regions

    SciTech Connect

    Katanuma, I.; Masaki, S.; Sato, S.; Sekiya, K.; Ichimura, M.; Imai, T.

    2011-11-15

    The numerical simulation is performed in GAMMA10 A-divertor magnetic configuration, which is a candidate of remodeled device of the GAMMA10 tandem mirror [M. Inutake et al., Phys. Rev. Lett. 55, 939 (1985)]. Both divertor and dipole regions are included in the numerical calculation, which is a new point. The electron short circuit effect along x-point, therefore, is not assumed so that it is not used the boundary condition of the electrostatic perturbations being zero at the separatrix on which the magnetic field lines pass through x-point. The simulation results reveal that the dipole field plays a role of a good magnetic field line curvature to the GAMMA10 A-divertor, and so the flute modes are stabilized without help of electron short circuit effects.

  4. The dynamic ergodic divertor in the TEXTOR tokamak: plasma response to dynamic helical magnetic field perturbations

    NASA Astrophysics Data System (ADS)

    Finken, K. H.; Abdullaev, S. S.; Biel, W.; de Bock, M. F. M.; Busch, C.; Farshi, E.; von Hellermann, M.; Hogeweij, G. M. D.; Jakubowski, M.; Jaspers, R.; Koslowski, H. R.; Kraemer-Flecken, A.; Lazaros, A.; Lehnen, M.; Liang, Y.; Nicolai, A.; Schmitz, O.; Unterberg, B.; Westerhof, E.; Wolf, R.; Zimmermann, O.; de Baar, M.; Bertschinger, G.; Brezinsek, S.; Classen, I. G. J.; Donné, A. J. H.; Esser, H. G.; Gerhauser, H.; Giesen, B.; Harting, D.; Hoekzema, J. A.; Huettemann, P. W.; Jachmich, S.; Jakubowska, K.; Kalupin, D.; Kelly, F.; Kikuchi, Y.; Kirschner, A.; Koch, R.; Korten, M.; Kreter, A.; Krom, J.; Kruezi, U.; Litnovsky, A.; Loozen, X.; Lopes Cardozo, N. J.; Lyssoivan, A.; Marchuk, O.; Mertens, Ph; Messiaen, A.; Neubauer, O.; Philipps, V.; Pospieszczyk, A.; Reiser, D.; Reiter, D.; Rogister, A. L.; Van Rompuy, T.; Savtchkov, A.; Samm, U.; Schorn, R. P.; Schueller, F. C.; Schweer, B.; Sergienko, G.; Telesca, K. H. G.; Tokar, M.; Van Oost, G.; Uhlemann, R.; Van Wassenhove, G.; Weynants, R.; Wiesen, S.; Xu, Y.

    2004-12-01

    Recently, the dynamic ergodic divertor (DED) of TEXTOR has been studied in an m/n = 3/1 set-up which is characterized by a relatively deep penetration of the perturbation field. The perturbation field creates (a) a helical divertor, (b) an ergodic pattern and/or (c) excitation of tearing modes, depending on whether the DED current is static, rotating in the co-current direction or in the counter-current direction. Characteristic divertor properties such as the high recycling regime or enhanced shielding have been studied. A strong effect of the ergodization is spin up of the plasma rotation, possibly due to the electric field at the plasma edge. Tearing modes are excited in a rather reproducible way and their excitation threshold value, their motion and their reduction due to the ECRH/ECCD have been studied. The different scenarios are characterized by strong modifications of the toroidal velocity profile and by a reduced or enhanced radial transport.

  5. Attainment of high confinement in neutral beam heated divertor discharges in the PDX tokamak

    NASA Astrophysics Data System (ADS)

    Kaye, S. M.; Bell, M. G.; Bol, K.; Boyd, D.; Brau, K.; Buchenauer, D.; Budny, R.; Cavallo, A.; Couture, P.; Crowley, T.; Darrow, D. S.; Eubank, H.; Fonck, R. J.; Goldston, R.; Grek, B.; Jaehnig, K. P.; Johnson, D.; Kaita, R.; Kugel, H.; Leblanc, B.; Manickam, J.; Manos, D.; Mansfield, D.; Mazzucato, E.; McCann, R.; McCune, D.; McGuire, K.; Mueller, D.; Murdock, A.; Okabayashi, M.; Okano, K.; Owens, D. K.; Post, D. E.; Reusch, M.; Schmidt, G. L.; Sesnic, S.; Slusher, R.; Suckewer, S.; Surko, C.; Takahashi, H.; Tenney, F.; Towner, H.; Valley, J.

    1984-05-01

    The PDX divertor configuration has recently been converted from an open to a closed geometry to inhibit the return of neutral gas from the divertor region to the main chamber. Since then, operation in a regime with high energy confinement in neutral beam heated discharges (ASDEX H-mode) has been routine over a wide range of operating conditions. These H-mode discharges are characterized by a sudden drop in divertor density and H α emission and a spontaneous rise in main chamber plasma density during neutral beam injection. The confinement time is found to scale nearly linearly with plasma current, but can be degraded due either to the presence of edge instabilities or heavy gas puffing. Detailed Thomson scattering temperature profiles show high values of Tc near the plasma edge (˜ 450 eV) with sharp radial gradients (˜ 400 eV/cm) near the separatrix. Density profiles are broad and also exhibit steep gradients close to the separatrix.

  6. Modelling the transport of deuterium and tritium neutral particles in a divertor plasma

    NASA Astrophysics Data System (ADS)

    Tokar, M. Z.; Kotov, V.

    2012-10-01

    A fluid model for transport of deuterium and tritium atoms in two-dimensional geometry of a poloidal divertor is elaborated by taking into account the coupling of both isotopes through the processes of cross-charge-exchange. Calculations are performed for the plasma parameters predicted with the code package B2-EIRENE (SOLPS4.3) for the divertor region in ITER. The results demonstrate that the transparency of the scrape-off layer for neutral particles generated by recycling on target plates and recombination of electrons and ions in the plasma volume can be significantly different for deuterium and tritium atoms. This difference has to be taken into account by considering the global particle balances in a reactor. The numerical approach applied for calculations is verified by comparing with an analytical model elaborated for the case of plasma parameters homogeneous in the divertor domain.

  7. Viscous fingering with partial miscible fluids

    NASA Astrophysics Data System (ADS)

    Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

    2015-11-01

    When a less viscous fluid displaces a more viscous fluid, the contrast in viscosity destabilizes the interface between the two fluids, leading to the formation of fingers. Studies of viscous fingering have focused on fluids that are either fully miscible or perfectly immiscible. In practice, however, the miscibility of two fluids can change appreciably with temperature and pressure, and often falls into the case of partial miscibility, where two fluids have limited solubility in each other. Following our recent work for miscible (Jha et al., PRL 2011, 2013) and immiscible systems (Cueto-Felgueroso and Juanes, PRL 2012, JFM 2014), here we propose a phase-field model for fluid-fluid displacements in a Hele-Shaw cell, when the two fluids have limited (but nonzero) solubility in one another. Partial miscibility is characterized through the design of thermodynamic free energy of the two-fluid system. We elucidate the key dimensionless groups that control the behavior of the system. We present high-resolution numerical simulations of the model applied to the viscous fingering problem. On one hand, we demonstrate the effect of partial miscibility on the hydrodynamic instability. On the other, we elucidate the role of the degree of fingering on the rate of mutual fluid dissolution.

  8. Fingerspell: Let Your Fingers Do the Talking

    ERIC Educational Resources Information Center

    Scarlatos, Tony; Nesterenko, Dmitri

    2004-01-01

    In this article we discuss an application that translates hand gestures of the American Sign Language (ASL) alphabet and converts them to text. The FingerSpell application addresses the communication barrier of the deaf and the hearing-impaired by eliminating the need for a third party with knowledge of the American Sign Language, allowing a user…

  9. Transdermal anaesthesia for percutaneous trigger finger release.

    PubMed

    Yiannakopoulos, Christos K; Ignatiadis, Ioannis A

    2006-01-01

    The purpose of this study was to evaluate the safety and efficiency of transdermal anaesthesia using eutectic mixture of lidocaine and prilocaine (EMLA) in patients undergoing percutaneous trigger finger release and to compare it with lidocaine infiltration. In this prospective, randomised study percutaneous release of the A1 annular pulley was performed to treat stenosing tenosynovitis (trigger finger syndrome) in 50 patients (50 fingers). The procedure was performed either under transdermal anaesthesia using EMLA applied transcutaneously 120 minutes prior to the operation (Group A, n = 25) or using local infiltration anaesthesia using lidocaine (Group B, n = 25). Pain experienced during administration of anaesthesia and during the operation was assessed using a 10-point Visual Analogue Pain Scale (VAPS), while all patients rated the effectiveness of anaesthesia with a 5-point scale. There were no significant differences between the two groups in the VAPS during the operation (1.33 +/- 0.52 versus 1.59 +/- 0.87) and the satisfaction scores (4.6 +/- 0.2 versus 4.4 +/- 0.3). The VAPS score during the administration of anaesthesia was statistically significantly less in the EMLA group (0 versus 5.96 +/- 2.41). All patients were satisfied with the final result of the operation. Percutaneous trigger finger release can be performed as an office procedure with the use of EMLA avoiding the use of injectable local infiltration anaesthesia. PMID:17405199

  10. Fingers Make a Comeback in Math

    ERIC Educational Resources Information Center

    Brooks, Andree

    1978-01-01

    Describes a new idea in finger-counting developed by 31 year old Hang Young Pai, a Korean teacher living in New York. It is called Chisanbop and it comes from a more advanced hand-calculation system used in the Orient in conjunction with the abacus. It is applicable for both elementary students and for more advanced mathematical applications, such…

  11. Sticky fingers: Adhesive properties of human fingertips.

    PubMed

    Spinner, Marlene; Wiechert, Anke B; Gorb, Stanislav N

    2016-02-29

    Fingertip friction is a rather well studied subject. Although the phenomenon of finger stickiness is known as well, the pull-off force and the adhesive strength of human finger tips have never been previously quantified. For the first time, we provided here characterization of adhesive properties of human fingers under natural conditions. Human fingers can generate a maximum adhesive force of 15mN on a smooth surface of epoxy resin. A weak correlation of the adhesive force and the normal force was found on all test surfaces. Up to 300mN load, an increase of the normal force leads to an increase of the adhesive force. On rough surfaces, the adhesive strength is significantly reduced. Our data collected from untreated hands give also an impression of an enormous scattering of digital adhesion depending on a large set of inter-subject variability and time-dependent individual factors (skin texture, moisture level, perspiration). The wide inter- and intra-individual range of digital adhesion should be considered in developing of technical and medical products. PMID:26892897

  12. Coriolis effects on fingering patterns under rotation.

    PubMed

    Alvarez-Lacalle, Enrique; Gadêlha, Hermes; Miranda, José A

    2008-08-01

    The development of immiscible viscous fingering patterns in a rotating Hele-Shaw cell is investigated. We focus on understanding how the time evolution and the resulting morphologies are affected by the action of the Coriolis force. The problem is approached analytically and numerically by employing a vortex sheet formalism. The vortex sheet strength and a linear dispersion relation are derived analytically, revealing that the most relevant Coriolis force contribution comes from the normal component of the averaged interfacial velocity. It is shown that this normal velocity, uniquely due to the presence of the Coriolis force, is responsible for the complex-valued nature of the linear dispersion relation making the linear phases vary with time. Fully nonlinear stages are studied through intensive numerical simulations. A suggestive interplay between inertial and viscous effects is found, which modifies the dynamics, leading to different pattern-forming structures. The inertial Coriolis contribution plays a characteristic role: it generates a phase drift by deviating the fingers in the sense opposite to the actual rotation of the cell. However, the direction and intensity of finger bending is predominantly determined by viscous effects, being sensitive to changes in the magnitude and sign of the viscosity contrast. The finger competition behavior at advanced time stages is also discussed.

  13. Fingering phenomena during grain-grain displacement

    NASA Astrophysics Data System (ADS)

    Mello, Nathália M. P.; Paiva, Humberto A.; Combe, G.; Atman, A. P. F.

    2016-05-01

    Spontaneous formation of fingered patterns during the displacement of dense granular assemblies was experimentally reported few years ago, in a radial Hele-Shaw cell. Here, by means of discrete element simulations, we have recovered the experimental findings and extended the original study to explore the control parameters space. In particular, using assemblies of grains with different geometries (monodisperse, bidisperse, or polydisperse), we measured the macroscopic stress tensor in the samples in order to confirm some conjectures proposed in analogy with Saffman-Taylor viscous fingering phenomena for immiscible fluids. Considering an axial setup which allows to control the discharge of grains and to follow the trajectory and the pressure gradient along the displacing interface, we have applied the Darcy law for laminar flow in fluids in order to measure an "effective viscosity" for each assembly combination, in an attempt to mimic variation of the viscosity ratio between the injected/displaced fluids in the Saffman-Taylor experiment. The results corroborate the analogy with the viscous fluids displacement, with the bidisperse assembly corresponding to the less viscous geometry. But, differently to fluid case, granular fingers only develop for a specific combination of displaced/injected geometries, and we have demonstrated that it is always related with the formation of a force chain network along the finger direction.

  14. Optimization of tungsten castellated structures for the ITER divertor

    NASA Astrophysics Data System (ADS)

    Litnovsky, A.; Hellwig, M.; Matveev, D.; Komm, M.; van den Berg, M.; De Temmerman, G.; Rudakov, D.; Ding, F.; Luo, G.-N.; Krieger, K.; Sugiyama, K.; Pitts, R. A.; Petersson, P.

    2015-08-01

    In ITER, the plasma-facing components (PFCs) of the first wall and the divertor armor will be castellated to improve their thermo-mechanical stability and to limit forces due to induced currents. The fuel accumulation in the gaps may significantly contribute to the in-vessel fuel inventory. Castellation shaping may be the most straightforward way to minimize the fuel inventory and to alleviate the thermal loads onto castellations. A new castellation shape was proposed and comparative modeling of conventional (rectangular) and shaped castellation was performed for ITER conditions. Shaped castellation was predicted to be capable to operate under stationary heat load of 20 MW/m2. An 11-fold decrease of beryllium (Be) content in the gaps of the shaped cells alone with a 7-fold decrease of carbon content was predicted. In order to validate the predictive capabilities of modeling tools used for ITER conditions, the dedicated modeling with the same codes was made for existing tokamaks and benchmarked with the results of multi-machine experiments. For the castellations exposed in TEXTOR and DIII-D, the carbon amount in the gaps of shaped cells was 1.9-2.3 times smaller than that of rectangular ones. Modeling for TEXTOR conditions yielded to 1.5-fold decrease of carbon content in the gaps of shaped castellation outlining fair agreement with the experiment. At the same time, a number of processes, like enhanced erosion of molten layer yet need to be implemented in the codes in order to increase the accuracy of predictions for ITER.

  15. Enhancement of cross-field transport into the private region of detached-divertor in Large Helical Device

    SciTech Connect

    Tanaka, H.; Ohno, N.; Tsuji, Y.; Kajita, S.; Masuzaki, S.; Kobayashi, M.; Morisaki, T.; Tsuchiya, H.; Komori, A.

    2010-10-15

    The fluctuation of ion saturation currents in the attached- and detached-divertor plasmas of the Large Helical Device [Fujiwara et al., Nucl. Fusion 41, 1355 (2001)] has been measured using a Langmuir probe array embedded in a divertor plate. Analytical results indicate that these fluctuation properties differ considerably from each other; for instance, the mean value distribution expands to and positive spikes propagate toward a private region from the divertor leg in the detached-divertor. We investigated the magnetic field lines traced from probe electrodes by using the KMAG code [Nakamura et al., J. Plasma Fusion Res. 69, 41 (1993)], and it is then confirmed that the propagation direction of positive spikes corresponds to that predicted by the theory of blobby plasma transport. This phenomenon is expected to lead to the broadening of plasma particle and heat fluxes to the divertor plate.

  16. Finger force perception during ipsilateral and contralateral force matching tasks

    PubMed Central

    Park, Woo-Hyung; Leonard, Charles T.; Li, Sheng

    2010-01-01

    The aims of the present study were to compare matching performance between ipsilateral and contralateral finger force matching tasks and to examine the effect of handedness on finger force perception. Eleven subjects were instructed to produce reference forces by an instructed finger (index – I or little – L finger) and to reproduce the same amount force by the same or a different finger within the hand (i.e., ipsilateral matching task), or by a finger of the other hand (i.e., contralateral matching task). The results of the ipsilateral and contralateral tasks in the present study commonly showed that 1) the reference and matching forces were matched closely when the two forces were produced by the same or homologous finger(s) such as I/I task; 2) the weaker little finger underestimated the magnitude of reference force of the index finger (I/L task), even with the higher level of effort (relative force), but the two forces were matched when considering total finger forces; 3) the stronger index finger closely matched the reference force of the little finger with the lower level of relative force (i.e., L/I task); 4) when considering the constant errors, I/L tasks showed an underestimation and L/I tasks showed an overestimation compared to I/I tasks. There was no handedness effect during ipsilateral tasks. During the contralateral task, the dominant hand overestimated the force of the non-dominant hand, while the non-dominant hand attempted to match the absolute force of the dominant hand. The overall results support the notion that the absolute, rather than relative, finger force is perceived and reproduced during ipsilateral and contralateral finger force matching tasks, indicating the uniqueness of finger force perception. PMID:18488212

  17. ELM PARTICLE AND ENERGY TRANSPORT IN THE SOL AND DIVERTOR OF DIII-D

    SciTech Connect

    FENSTERMACHER,ME; LEONARD,AW; SNYDER,PB; BOEDO,JA; COLCHIN,RJ; GROEBNER,RJ; GRAY,DS; GROTH,M; HOLLMANN,E; LASNIER,CJ; OSBORNE,TH; PETRIE,TW; RUDAKOV,DL; TAKAHASHI,H; WATKINS,JG; ZENG,L

    2003-04-01

    A271 ELM PARTICLE AND ENERGY TRANSPORT IN THE SOL AND DIVERTOR OF DIII-D. Results from a series of dedicated experiments measuring the effect of particle and energy pulses from Type-I Edge Localized Modes (ELMs) in the DIII-D scrape-off layer (SOL) and divertor are compared with a simple model of ELM propagation in the boundary plasma. The simple model asserts that the propagation of ELM particle and energy perturbations is dominated by ion parallel convection along SOL fields lines and the recovery from the ELM perturbation is determined by recycling physics. Time scales associated with the initial changes of boundary plasma parameters are expected to be on the order of the ion transit time from the outer midplane, where the ELM instability is initiated, to the divertor targets. To test the model, the ion convection velocity is changed in the experiment by varying the plasma density. At moderate to high density, n{sub e}/n{sub Gr} = 0.5-0.8, the delays in the response of the boundary plasma to the midplane ELM pulses, the density dependence of those delays and other observations are consistent with the model. However, at the lowest densities, n{sub e}/n{sub Gr} {approx} 0.35, small delays between the response sin the two divertors, and changes in the response of the pedestal thermal energy to ELM events, indicate that additional factors including electron conduction in the SOL, the pre-ELM condition of the divertor plasma, and the ratio of ELM instability duration to SOL transit time, may be playing a role. The results show that understanding the response of the SOL and divertor plasmas to ELMs, for various pre-ELM conditions, is just as important to predicting the effect of ELM pulses on the target surfaces of future devices as is predicting the characteristics of the ELM perturbation of the core plasma.

  18. Crossover from capillary fingering to viscous fingering for immiscible unstable flow:Experiment and modeling.

    PubMed

    Ferer, M; Ji, Chuang; Bromhal, Grant S; Cook, Joshua; Ahmadi, Goodarz; Smith, Duane H

    2004-01-01

    Invasion percolation with trapping (IPT) and diffusion-limited aggregation (DLA) are simple fractal models, which are known to describe two-phase flow in porous media at well defined, but unphysical limits of the fluid properties and flow conditions. A decade ago, Fernandez, Rangel, and Rivero predicted a crossover from IPT (capillary fingering) to DLA (viscous fingering) for the injection of a zero-viscosity fluid as the injection velocity was increased from zero. [Phys. Rev. Lett. 67, 2958 (1991)

  19. 21 CFR 888.3230 - Finger joint polymer constrained prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Finger joint polymer constrained prosthesis. 888... SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3230 Finger joint polymer constrained prosthesis. (a) Identification. A finger joint polymer constrained prosthesis is a device...

  20. 21 CFR 888.3230 - Finger joint polymer constrained prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Finger joint polymer constrained prosthesis. 888... SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3230 Finger joint polymer constrained prosthesis. (a) Identification. A finger joint polymer constrained prosthesis is a device...

  1. 21 CFR 888.3230 - Finger joint polymer constrained prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Finger joint polymer constrained prosthesis. 888... SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3230 Finger joint polymer constrained prosthesis. (a) Identification. A finger joint polymer constrained prosthesis is a device...

  2. Robot-Assisted Guitar Hero for Finger Rehabilitation after Stroke

    PubMed Central

    Taheri, Hossein; Rowe, Justin B.; Gardner, David; Chan, Vicky; Reinkensmeyer, David J.; Wolbrecht, Eric T.

    2014-01-01

    This paper describes the design and testing of a robotic device for finger therapy after stroke: FINGER (Finger Individuating Grasp Exercise Robot). FINGER makes use of stacked single degree-of-freedom mechanisms to assist subjects in moving individual fingers in a naturalistic grasping pattern through much of their full range of motion. The device has a high bandwidth of control (−3dB at approximately 8 Hz) and is backdriveable. These characteristics make it capable of assisting in grasping tasks that require precise timing. We therefore used FINGER to assist individuals with a stroke (n = 8) and without impairment (n = 4) in playing a game similar to Guitar Hero©. The subjects attempted to move their fingers to target positions at times specified by notes that were graphically streamed to popular music. We show here that by automatically adjusting the robot gains, it is possible to use FINGER to modulate the subject’s success rate at the game, across a range of impairment levels. Modulating success rates did not alter the stroke subject’s effort, although the unimpaired subjects exerted more force when they were made less successful. We also present a novel measure of finger individuation that can be assessed as individuals play Guitar Hero with FINGER. The results demonstrate the ability of FINGER to provide controlled levels of assistance during an engaging computer game, and to quantify finger individuation after stroke. PMID:23366783

  3. Robot-assisted Guitar Hero for finger rehabilitation after stroke.

    PubMed

    Taheri, Hossein; Rowe, Justin B; Gardner, David; Chan, Vicky; Reinkensmeyer, David J; Wolbrecht, Eric T

    2012-01-01

    This paper describes the design and testing of a robotic device for finger therapy after stroke: FINGER (Finger Individuating Grasp Exercise Robot). FINGER makes use of stacked single degree-of-freedom mechanisms to assist subjects in moving individual fingers in a naturalistic grasping pattern through much of their full range of motion. The device has a high bandwidth of control (-3dB at approximately 8 Hz) and is backdriveable. These characteristics make it capable of assisting in grasping tasks that require precise timing. We therefore used FINGER to assist individuals with a stroke (n= 8) and without impairment (n= 4) in playing a game similar to Guitar Hero©. The subjects attempted to move their fingers to target positions at times specified by notes that were graphically streamed to popular music. We show here that by automatically adjusting the robot gains, it is possible to use FINGER to modulate the subject's success rate at the game, across a range of impairment levels. Modulating success rates did not alter the stroke subject's effort, although the unimpaired subjects exerted more force when they were made less successful. We also present a novel measure of finger individuation that can be assessed as individuals play Guitar Hero with FINGER. The results demonstrate the ability of FINGER to provide controlled levels of assistance during an engaging computer game, and to quantify finger individuation after stroke. PMID:23366783

  4. Robot-assisted Guitar Hero for finger rehabilitation after stroke.

    PubMed

    Taheri, Hossein; Rowe, Justin B; Gardner, David; Chan, Vicky; Reinkensmeyer, David J; Wolbrecht, Eric T

    2012-01-01

    This paper describes the design and testing of a robotic device for finger therapy after stroke: FINGER (Finger Individuating Grasp Exercise Robot). FINGER makes use of stacked single degree-of-freedom mechanisms to assist subjects in moving individual fingers in a naturalistic grasping pattern through much of their full range of motion. The device has a high bandwidth of control (-3dB at approximately 8 Hz) and is backdriveable. These characteristics make it capable of assisting in grasping tasks that require precise timing. We therefore used FINGER to assist individuals with a stroke (n= 8) and without impairment (n= 4) in playing a game similar to Guitar Hero©. The subjects attempted to move their fingers to target positions at times specified by notes that were graphically streamed to popular music. We show here that by automatically adjusting the robot gains, it is possible to use FINGER to modulate the subject's success rate at the game, across a range of impairment levels. Modulating success rates did not alter the stroke subject's effort, although the unimpaired subjects exerted more force when they were made less successful. We also present a novel measure of finger individuation that can be assessed as individuals play Guitar Hero with FINGER. The results demonstrate the ability of FINGER to provide controlled levels of assistance during an engaging computer game, and to quantify finger individuation after stroke.

  5. 21 CFR 888.3230 - Finger joint polymer constrained prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Finger joint polymer constrained prosthesis. 888... SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3230 Finger joint polymer constrained prosthesis. (a) Identification. A finger joint polymer constrained prosthesis is a device...

  6. 21 CFR 888.3230 - Finger joint polymer constrained prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Finger joint polymer constrained prosthesis. 888... SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3230 Finger joint polymer constrained prosthesis. (a) Identification. A finger joint polymer constrained prosthesis is a device...

  7. Gas fueling with an axisymmetric magnetic divertor in the Tara tandem mirror

    SciTech Connect

    Post, R.S.; Brau, K.; Horne, S.; Casey, J.; Golovato, S.; Sevillano, E.; Shuy, G.; Smith, D.K.

    1987-07-01

    An axisymmetric divertor has been installed at the central cell midplane of Tara to provide magnetohydrodynamics stability and to generate a high-density halo at the edge of the plasma. A dense halo aids sloshing ion buildup in the plug cells and increases shielding of the core plasma from charge exchange recombination. Separate gas fueling of the halo in the divertor allows for the different fueling requirements of the potential-confined core plasma and the flow-confined edge during plugged operation.

  8. Nonlinear Impact of Edge Localized Modes on Carbon Erosion in the Divertor of the JET Tokamak

    SciTech Connect

    Kreter, A.; Esser, H. G.; Brezinsek, S.; Kirschner, A.; Philipps, V.; Coad, J. P.; Fundamenski, W.; Widdowson, A.; Pitts, R. A.

    2009-01-30

    The impact of edge localized modes (ELMs) carrying energies of up to 450 kJ on carbon erosion in the JET inner divertor is assessed by means of time resolved measurements using an in situ quartz microbalance diagnostic. The inner target erosion is strongly nonlinearly dependent on the ELM energy: a single 400 kJ ELM produces the same carbon erosion as ten 150 kJ events. The ELM-induced enhanced erosion is attributed to the presence of codeposited carbon-deuterium layers on the inner divertor target, which are thermally decomposed under the impact of ELMs.

  9. The dynamic ergodic divertor in the TEXTOR tokamak: First results and future prospects

    NASA Astrophysics Data System (ADS)

    Wolf, R. C.; Finken, K. H.; Abdullaev, S. S.; Giesen, B.; Jakubowski, M.; Kobayashi, M.; Koslowski, H. R.; Krämer-Flecken, A.; Lehnen, M.; Neubauer, O.; Pospieszczyk, A.; Samm, U.; Schweer, B.; Sergienko, G.; Unterberg, B.; Zimmermann, O.; Jaspers, R.; Westerhof, E.; Jachmich, S.; Koch, R.; Spatschek, K. H.

    2003-10-01

    The tokamak TEXTOR has been equipped with a dynamic ergodic divertor which is resonant to the edge magnetic flux surface with q=3 and can be operated between DC and 10 kHz. First results indicate a redistribution of particle and energy fluxes which becomes evident in a characteristic stripe pattern. The dynamic mode leads to a uniform divertor target load. Prospects of confinement and MHD stability control, based on the specific edge properties outside the last closed flux surface (an ergodic region followed by a laminar zone with short connection lengths) together with the possibility to transfer momentum to the plasma, are discussed.

  10. Left hand finger force in violin playing: tempo, loudness, and finger differences.

    PubMed

    Kinoshita, Hiroshi; Obata, Satoshi

    2009-07-01

    A three-dimensional force transducer was installed in the neck of a violin under the A string at the D5 position in order to study the force with which the violinist clamps the string against the fingerboard under normal playing conditions. Violinists performed repetitive sequences of open A- and fingered D-tones using the ring finger at tempi of 1, 2, 4, 8, and 16 notes/s at mezzo-forte. At selected tempi, the effects of dynamic level and the use of different fingers were investigated as well. The force profiles were clearly dependent on tempo and dynamic level. At slow tempi, the force profiles were characterized by an initial pulse followed by a level force to the end of the finger contact period. At tempi higher than 2 Hz, only pulsed profiles were observed. The peak force exceeded 4.5 N at 1 and 2 Hz and decreased to 1.7 N at 16 Hz. All force and impulse values were lower at softer dynamic levels, and when using the ring or little finger compared to the index finger. PMID:19603895

  11. Monte Carlo simulations of tungsten redeposition at the divertor target

    NASA Astrophysics Data System (ADS)

    Chankin, A. V.; Coster, D. P.; Dux, R.

    2014-02-01

    Recent modeling of controlled edge-localized modes (ELMs) in ITER with tungsten (W) divertor target plates by the SOLPS code package predicted high electron temperatures (>100 eV) and densities (>1 × 1021 m-3) at the outer target. Under certain scenarios W sputtered during ELMs can penetrate into the core in quantities large enough to cause deterioration of the discharge performance, as was shown by coupled SOLPS5.0/STRAHL/ASTRA runs. The net sputtering yield, however, was expected to be dramatically reduced by the ‘prompt redeposition’ during the first Larmor gyration of W1+ (Fussman et al 1995 Proc. 15th Int. Conf. on Plasma Physics and Controlled Nuclear Fusion Research (Vienna: IAEA) vol 2, p 143). Under high ne/Te conditions at the target during ITER ELMs, prompt redeposition would reduce W sputtering by factor p-2 ˜ 104 (with p ≡ τionωgyro ˜ 0.01). However, this relation does not include the effects of multiple ionizations of sputtered W atoms and the electric field in the magnetic pre-sheath (MPS, or ‘Chodura sheath’) and Debye sheath (DS). Monte Carlo simulations of W redeposition with the inclusion of these effects are described in the paper. It is shown that for p ≪ 1, the inclusion of multiple W ionizations and the electric field in the MPS and DS changes the physics of W redeposition from geometrical effects of circular gyro-orbits hitting the target surface, to mainly energy considerations; the key effect is the electric potential barrier for ions trying to escape into the main plasma. The overwhelming majority of ions are drawn back to the target by a strong attracting electric field. It is also shown that the possibility of a W self-sputtering avalanche by ions circulating in the MPS can be ruled out due to the smallness of the sputtered W neutral energies, which means that they do not penetrate very far into the MPS before ionizing; thus the W ions do not gain a large kinetic energy as they are accelerated back to the surface by the

  12. Effect of Finger Posture on the Tendon Force Distribution Within the Finger Extensor Mechanism

    PubMed Central

    Lee, Sang Wook; Chen, Hua; Towles, Joseph D.; Kamper, Derek G.

    2009-01-01

    Understanding the transformation of tendon forces into joint torques would greatly aid in the investigation of the complex temporal and spatial coordination of multiple muscles in finger movements. In this study, the effects of the finger posture on the tendon force transmission within the finger extensor apparatus were investigated. In five cadaver specimens, a constant force was applied sequentially to the two extrinsic extensor tendons in the index finger, extensor digitorum communis and extensor indicis proprius. The responses to this loading, i.e. fingertip force/moment and regional strains of the extensor apparatus, were measured and analyzed to estimate the tendon force transmission into the terminal and central slips of the extensor hood. Repeated measures analysis of variance revealed that the amount of tendon force transmitted to each tendon slip was significantly affected by finger posture, specifically by the interphalangeal (IP) joint angles (p < 0.01). Tendon force transmitted to each of the tendon slips was found to decrease with the IP flexion. The main effect of the metacarpophalangeal joint angle was not as consistent as the IP angle, but there was a strong interaction effect for which MCP flexion led to large decreases in the slip forces (> 30%) when the IP joints were extended. The ratio of terminal slip force: central slip force remained relatively constant across postures at approximately 1.7:1. Force dissipation into surrounding structures was found to be largely responsible for the observed force-posture relationship. Due to the significance of posture in the force transmission to the tendon slips, the impact of finger posture should be carefully considered when studying finger motor control or examining injury mechanisms in the extensor apparatus. PMID:19045521

  13. Fingering dynamics driven by a precipitation reaction: Nonlinear simulations

    NASA Astrophysics Data System (ADS)

    Shukla, Priyanka; De Wit, A.

    2016-02-01

    A fingering instability can develop at the interface between two fluids when the more mobile fluid is injected into the less-mobile one. For example, viscous fingering appears when a less viscous (i.e., more mobile) fluid displaces a more viscous (and hence less mobile) one in a porous medium. Fingering can also be due to a local change in mobility arising when a precipitation reaction locally decreases the permeability. We numerically analyze the properties of the related precipitation fingering patterns occurring when an A +B →C chemical reaction takes place, where A and B are reactants in solution and C is a solid product. We show that, similarly to reactive viscous fingering patterns, the precipitation fingering structures differ depending on whether A invades B or vice versa. This asymmetry can be related to underlying asymmetric concentration profiles developing when diffusion coefficients or initial concentrations of the reactants differ. In contrast to reactive viscous fingering, however, precipitation fingering patterns appear at shorter time scales than viscous fingers because the solid product C has a diffusivity tending to zero which destabilizes the displacement. Moreover, contrary to reactive viscous fingering, the system is more unstable with regard to precipitation fingering when the high-concentrated solution is injected into the low-concentrated one or when the faster diffusing reactant displaces the slower diffusing one.

  14. Analysis of prosody in finger braille using electromyography.

    PubMed

    Miyagi, Manabi; Nishida, Masafumi; Horiuchi, Yasuo; Ichikawa, Akira

    2006-01-01

    Finger braille is one of the communication methods for the deaf blind. The interpreter types braille codes on the fingers of deaf blind. Finger braille seems to be the most suitable medium for real-time communication by its speed and accuracy of transmitting characters. We hypothesize that the prosody information exists in the time structure and strength of finger braille typing. Prosody is the paralinguistic information that has functions to transmit the sentence structure, prominence, emotions and other form of information in real time communication. In this study, we measured the surface electromyography (sEMG) of finger movement to analyze the typing strength of finger braille. We found that the typing strength increases at the beginning of a phrase and a prominent phrase. The result shows the possibility that the prosody in the typing strength of finger braille can be applied to create an interpreter system for the deafblind.

  15. Nylon-muscle-actuated robotic finger

    NASA Astrophysics Data System (ADS)

    Wu, Lianjun; Jung de Andrade, Monica; Rome, Richard S.; Haines, Carter; Lima, Marcio D.; Baughman, Ray H.; Tadesse, Yonas

    2015-04-01

    This paper describes the design and experimental analysis of novel artificial muscles, made of twisted and coiled nylon fibers, for powering a biomimetic robotic hand. The design is based on circulating hot and cold water to actuate the artificial muscles and obtain fast finger movements. The actuation system consists of a spring and a coiled muscle within a compliant silicone tube. The silicone tube provides a watertight, expansible compartment within which the coiled muscle contracts when heated and expands when cooled. The fabrication and characterization of the actuating system are discussed in detail. The performance of the coiled muscle fiber in embedded conditions and the related characteristics of the actuated robotic finger are described.

  16. Analysis of finger extensor mechanism strains.

    PubMed

    Hurlbut, P T; Adams, B D

    1995-09-01

    Strains in the extensor mechanism of the finger were measured in a cadaver model using Hall-effect transducers. Several components of the mechanism were evaluated at different joint positions, with different intrinsic and extrinsic tendon loading conditions, and after creating a boutonnière deformity. Landsmeer's theory that predictable and obligatory interactions occur within the extensor mechanism during finger movement is strongly supported by our results. The concept of the Bunnell intrinsic-tightness test was confirmed. Results were consistent with clinical observations and current theories on the pathomechanics of claw and boutonnière deformities. Based on our experimental findings, we conclude that strain analysis is an effective method of evaluation of the extensor mechanism with potential for in vivo surgical applications.

  17. Surgical treatment of chronic mallet finger.

    PubMed

    Makhlouf, Vincent M; Deek, Nidal Al

    2011-06-01

    The literature to find the best approach to correct a chronic mallet finger deformity has been reviewed. All the evidence we found was type IV mallet finger injury, based on the CEBM classification. In the European literature, if correction of the proximal interphalangeal joint is not needed, and surgery is to be done on the distal interphalangeal joint only, then the most frequently reported technique involves the conversion of the chronic injury into an acute one by excising the scar and part of the joint capsule, and the extensor tendon is reattached with minor variations. An 80% to 100% success rate can be expected. In the US literature, the Fowler release is favored, but it does not reliably correct a flexion deformity of more than 35 degrees. Spiral retinacular reconstruction provides an excellent solution if the associated swan neck deformity needs to be corrected. PMID:21467915

  18. Low-Friction Joint for Robot Fingers

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F.

    1985-01-01

    Mechanical linkage allows adjacent parts to move relative to each other with low friction and with no chatter, slipping, or backlash. Low-friction joint of two surfaces in rolling contact, held in alinement by taut flexible bands. No sliding friction or "stick-slip" motion: Only rolling-contact and bending friction within bands. Proposed linkage intended for finger joints in mechanical hands for robots and manipulators.

  19. Poloidal divertor experiment with applied E vector x B vector/B/sup 2/ drift

    SciTech Connect

    Strait, E J

    1980-05-01

    It has been proposed that the E vector x B vector/B/sup 2/ drift arising from an externally applied electric field could be used in a tokamak or other toroidal device to remove plasma and impurities from the region near the wall and to reduce the amount of plasma striking the wall, either assisting or replacing a conventional magnetic field divertor. A poloidal magnetic divertor (without pumping chamber) was added to the Wisconsin Levitated Toroidal Octupole, and the octupole was operated with a tokamak-like magnetic field configuration (q = 0.7). A radial electric field was applied in the scrape-off zone, causing an E vector x B vector/B/sup 2/ drift with a large poloidal component. This reduced plasma flux reaching the wall of the toroid by up to a factor of 5 beyond the effect of the magnetic divertor, for divertor configurations with both high and low magnetic mirror ratios, in good agreement with a simple theoretical model. Plasma density and density scale length were also reduced in the scrape-off zone, in qualitative agreement with the model. This was not accompanied by any new instabilities in the scrape-off zone, nor by any appreciable degradation of confinement of the central plasma.

  20. Density fluctuations at high density in the ergodic divertor configuration of Tore Supra

    NASA Astrophysics Data System (ADS)

    Devynck, P.; Gunn, J.; Ghendrih, Ph.; Garbet, X.; Antar, G.; Beyer, P.; Boucher, C.; Honore, C.; Gervais, F.; Hennequin, P.; Quémeneur, A.; Truc, A.

    2001-03-01

    The effect of the ergodic divertor on the plasma edge in Tore Supra is to enhance the perpendicular transport through ergodization of the magnetic field lines [Ph. Ghendrih et al., Contrib. Plasma Phys. 32 (3&4) (1992) 179]. Nevertheless, the hot spots observed on the divertor plates during ergodic divertor operation indicate that the cross-field transport driven by the fluctuations is still playing an important role, although measurements by CO 2 laser scattering and reflectometry show a decrease of the turbulence level [J. Payan, X. Garbet, J.H. Chatenet et al., Nucl. Fusion 35 (1995) 1357; P. Beyer, X. Garbet, P. Ghendrih, Phys. Plasmas 5 (12) (1998) 4271]. In order to gain more understanding, fluctuation level and poloidal velocity have been measured with a reciprocating Langmuir probe biased to collect the ion saturation current ( jsat) and with a CO 2 laser scattering diagnostic. Though the relative fluctuation level behaves as previously observed at low density, a new interesting result is that this picture is gradually modified when the density is increased. Both diagnostics observe an increase of δn/ n with density in the ergodic region, which is not the usual behavior observed in limiter configuration. This increase is detected on both sides of the Er inversion radius and is therefore also affecting the plasma bulk. Finally, the confinement time is found to follow an L-mode law at all densities indicating that the ergodic divertor does not change the global confinement properties of the plasma.

  1. Effect of separatrix magnetic geometry on divertor behavior in DIII-D

    NASA Astrophysics Data System (ADS)

    Petrie, T. W.; Canik, J. M.; Lasnier, C. J.; Leonard, A. W.; Mahdavi, M. A.; Watkins, J. G.; Fenstermacher, M. E.; Ferron, J. R.; Groebner, R. J.; Hill, D. N.; Hyatt, A. W.; Holcomb, C. T.; Luce, T. C.; Moyer, R. A.; Stangeby, P. C.

    2013-07-01

    We report on recent experiments on DIII-D that examined the effects that variations in the parallel connection length in the scrape-off layer (SOL), L||, and the radial location of the outer divertor target, RTAR, have on divertor plasma properties. Two-point modeling of the SOL plasma predicts that larger values of L|| and RTAR should lower temperature and raise density at the outer divertor target for fixed upstream separatrix density and temperature, i.e., nTAR ∝ [RTAR]2[L||]6/7 and TTAR ∝ [RTAR]-2[L||]-4/7. The dependence of nTAR and TTAR on L|| was consistent with our data, but the dependence of nTAR and TTAR on RTAR was not. The surprising result that the divertor plasma parameters did not depend on RTAR in the predicted way may be due to convected heat flux, driven by escaping neutrals, in the more open configuration of the larger RTAR cases. Modeling results using the SOLPS code support this postulate.

  2. A tangentially viewing visible TV system for the DIII-D divertor

    SciTech Connect

    Fenstermacher, M.E.; Meyer, W.H.; Wood, R.D.

    1996-02-01

    A video camera system has been installed on the DIII-D tokamak for 2-D spatial studies of line emission in the lower divertor region. The system views the divertor tangentially from an outer port at approximately the height of the X-point. At the tangency plane the entire divertor from inner wall to outside the DIII-D bias ring is viewed with spatial resolution of approximately 1 cm. The image contains information from approximately 90 degrees of toroidal angle. In a recent upgrade, remotely controllable filter changers were added which have produced images from nominally identical shots using a series of spectral lines. Software was developed to calculate the response function matrix using distributed computing techniques and assuming toroidal symmetry. Standard sparse matrix algorithms are then used to invert the 3-D images onto a poloidal plane. Spatial resolution of the inverted images is 2 cm; higher resolution simply increases the size of the response function matrix. Initial results from a series of experiments with multiple identical shots show that the emission from CII and CIII, which appears along the inner scrape-off layer above and below the X-point during ELMing H-mode, moves outward and becomes localized near the X-point in Partially Detached Divertor (PDD) operation.

  3. L to H mode transitions and associated phenomena in divertor tokamaks

    NASA Astrophysics Data System (ADS)

    Punjabi, A.

    1990-09-01

    This is the final report for the research project titled, L to H Mode Transitions and Associated Phenomena in Divertor Tokamaks. The period covered by this project is the fiscal year 1990. This report covers the development of Advanced Two Chamber Model.

  4. A helical hydrogen-MARFE-like phenomenon in the divertor of the Wendelstein 7-AS stellarator

    NASA Astrophysics Data System (ADS)

    Wenzel, U.; König, R.; Pedersen, T. Sunn; the W7-AS Team

    2015-01-01

    In the island divertor of the W7-AS stellarator a high-density zone (HDZ) near the divertor plates was discovered some years ago (Ramasubramanian et al 2004 Nucl. Fusion 44 992-8) with electron densities up to 7 × 1020 m-3. We shed further light on this phenomenon by determining the poloidal and radial location of this zone and discussing potential implications of these findings. The HDZ is in the vicinity of, but clearly separated from the nearest X-point line. The carbon emission is clearly spatially separated, residing near or at the X-point lines. The HDZ shows many similarities with the hydrogen or wall MARFE in Textor-94 (Samm et al 1999 J. Nucl. Mater. 266-269 666). The structure is associated with a strongly increased neutral pressure, thus enabling efficient pumping. This offers the possibility for a very efficient exhaust regime in a stellarator with island divertor such as W7-X, simultaneously with significantly reduced convective heat loads onto the divertor itself. The spatial separation of the HDZ and the carbon radiation region may imply that such a state can be reached even in a non-carbon machine, and might therefore be DEMO-relevant.

  5. Development of ion source for simulation of edge localized mode in divertor plasma

    SciTech Connect

    Daibo, A. Okamoto, A.; Takahashi, H.; Kumagai, T.; Takahashi, T.; Tsubota, S.; Kitajima, S.

    2014-02-15

    A helium ion beam is injected into a linear plasma device for the development of an ion beam source simulating high energy particle flux in divertor plasma. Beam current density more than 10 mA/cm{sup 2} is extracted. Measurement of beam currents indicates that the beam is transported along the linear device and reaches to the downstream end plate.

  6. Melt damage to the JET ITER-like Wall and divertor

    NASA Astrophysics Data System (ADS)

    Matthews, G. F.; Bazylev, B.; Baron-Wiechec, A.; Coenen, J.; Heinola, K.; Kiptily, V.; Maier, H.; Reux, C.; Riccardo, V.; Rimini, F.; Sergienko, G.; Thompson, V.; Widdowson, A.; Contributors, JET

    2016-02-01

    In October 2014, JET completed a scoping study involving high power scenario development in preparation for DT along with other experiments critical for ITER. These experiments have involved intentional and unintentional melt damage both to bulk beryllium main chamber tiles and to divertor tiles. This paper provides an overview of the findings of concern for machine protection in JET and ITER, illustrating each case with high resolution images taken by remote handling or after removal from the machine. The bulk beryllium upper dump plate tiles and some other protection tiles have been repeatedly flash melted by what we believe to be mainly fast unmitigated disruptions. The flash melting produced in this way is seen at all toroidal locations and the melt layer is driven by j × B forces radially outward and upwards against gravity. In contrast, the melt pools caused while attempting to use MGI to mitigate deliberately generated runaway electron beams are localized to several limiters and the ejected material appears less influenced by j × B forces and shows signs of boiling. In the divertor, transient melting of bulk tungsten by ELMs was studied in support of the ITER divertor material decision using a specially prepared divertor module containing an exposed edge. Removal of the module from the machine in 2015 has provided improved imaging of the melt and this confirms that the melt layers are driven by ELMs. No other melt damage to the other 9215 bulk tungsten lamellas has yet been observed.

  7. Enhanced \\boldsymbol{\\vec{{E}}\\times \\vec{{B}}} drift effects in the TCV snowflake divertor

    NASA Astrophysics Data System (ADS)

    Canal, G. P.; Lunt, T.; Reimerdes, H.; Duval, B. P.; Labit, B.; Vijvers, W. A. J.; the TCV Team

    2015-11-01

    Measurements of various plasma parameters at the divertor targets of snowflake (SF) and conventional single-null configurations indicate an enhanced effect of the E× B drift in the scrape-off layer of plasmas in the SF configuration. Plasma boundary transport simulations using the EMC3-Eirene code show that the poloidal gradients of the kinetic profiles in the vicinity of the null-point of a SF divertor are substantially larger than those of a conventional single-null configuration. These gradients are expected to drive larger E× B flows in the SF divertor and are thought to be responsible for the formation of the double-peaked particle and heat flux target profiles observed experimentally. Experiments in forward and reversed toroidal magnetic field directions further support this conclusion. The formation of such a double-peaked profiles is enhanced at higher plasma densities and may have beneficial effects on the divertor heat loads since they lead to broader target profiles and lower peak heat fluxes.

  8. Divertor heat loads in RMP ELM controlled H-mode plasmas on DIII-D*

    SciTech Connect

    Jakubowski, M; Lasnier, C; Schmitz, O; Evans, T; Fenstermacher, M; Groth, M; Watkins, J; Eich, T; Moyer, R; Wolf, R; Baylor, L; Boedo, J; Burrell, K; Frerichs, H; deGrassie, J; Gohil, P; Joseph, I; Lehnen, M; Leonard, A; Petty, C; Pinsker, R; Reiter, D; Rhodes, T; Samm, U; Snyder, P; Stoschus, H; Osborne, T; Unterberg, B; West, W

    2008-10-13

    In this paper the manipulation of power deposition on divertor targets at DIII-D by application of resonant magnetic perturbations (RMPs) is analyzed. It has been found that heat transport shows a different reaction to the applied RMP depending on the plasma pedestal collisionality. At pedestal electron collisionality above 0.5 the heat flux during the ELM suppressed phase is of the same order as the inter-ELM in the non-RMP phase. Below this collisionality value we observe a slight increase of the total power flux to the divertor. This can be caused by much more negative potential at the divertor surface due to hot electrons reaching the divertor surface from the pedestal area and/or so called pump out effect. In the second part we discuss modification of ELM behavior due to the RMP. It is shown, that the width of the deposition pattern in ELMy H-mode depends linearly on the ELM deposited energy, whereas in the RMP phase of the discharge those patterns seem to be controlled by the externally induced magnetic perturbation. D{sub 2} pellets injected into the plasma bulk during ELM-free RMP H-mode lead in some cases to a short term small transients, which have very similar properties to ELMs in the initial RMP-on phase.

  9. Parametric analysis of the thermal effects on the divertor in tokamaks during plasma disruptions

    SciTech Connect

    Bruhn, M.L.

    1988-04-01

    Plasma disruptions are an ever present danger to the plasma-facing components in today's tokamak fusion reactors. This threat results from our lack of understanding and limited ability to control this complex phenomenon. In particular, severe energy deposition occurs on the divertor component of the double-null configured tokamak reactor during such disruptions. A hybrid computational model developed to estimate and graphically illustrate global thermal effects of disruptions on the divertor plates is described in detail. The quasi-two-dimensional computer code, TADDPAK (Thermal Analysis Divertor during Disruptions PAcKage), is used to conduct parametric analysis for the TIBER II Tokamak Engineering Test Reactor Design. The dependence of these thermal effects on divertor material choice, disruption pulse length, disruption pulse shape, and the characteristic thickness of the plasma scrape-off layer is investigated for this reactor design. Results and conclusions from this analysis are presented. Improvements to this model and issues that require further investigation are discussed. Cursory analysis for ITER (International Thermonuclear Experimental Reactor) is also presented in the appendix. 75 refs., 49 figs., 10 tabs.

  10. Visual Foraging With Fingers and Eye Gaze.

    PubMed

    Jóhannesson, Ómar I; Thornton, Ian M; Smith, Irene J; Chetverikov, Andrey; Kristjánsson, Árni

    2016-03-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints. PMID:27433323

  11. Visual Foraging With Fingers and Eye Gaze

    PubMed Central

    Thornton, Ian M.; Smith, Irene J.; Chetverikov, Andrey; Kristjánsson, Árni

    2016-01-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints. PMID:27433323

  12. Multi-finger Prehension: An overview

    PubMed Central

    Zatsiorsky, Vladimir M.; Latash, Mark L.

    2009-01-01

    This paper reviews the available experimental evidence on what people do when they grasp an object with several digits and then manipulate it. In addition to the Introduction, the paper includes three parts each addressing a specific aspect of multi-finger prehension. Part II discusses manipulation forces, i.e. the resultant force and moment of force exerted on the object, and the digits contribution to such force production. Part III deals with internal forces defined as forces that cancel each other and do not disturb object equilibrium. The role of the internal forces in maintaining the object stability is discussed with respect to such issues as slip prevention, tilt prevention and resistance to perturbations. Part IV is devoted to the motor control of prehension. It covers such topics as prehension synergies, chain effects, the principle of superposition, inter-finger connection matrices and reconstruction of neural commands, mechanical advantage of the fingers, and the simultaneous digit adjustment to several mutually reinforcing or conflicting demands. PMID:18782719

  13. Visual Foraging With Fingers and Eye Gaze.

    PubMed

    Jóhannesson, Ómar I; Thornton, Ian M; Smith, Irene J; Chetverikov, Andrey; Kristjánsson, Árni

    2016-03-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints.

  14. Small-scale behavior of single gravity-driven fingers in an initially dry fracture

    SciTech Connect

    Nicholl, M.J.; Glass, R.J.; Nguyen, H.A.

    1992-12-31

    Experiments investigating the behavior of individual, gravity-driven fingers in an initially dry, rough-walled analog fracture are presented. Fingers were initiated from constant flow to a point source. Finger structure is described in detail; specific phenomena observed include: desaturation behind the finger-tip, variation in finger path, intermittent flow structures, finger-tip bifurcation, and formation of dendritic sub-fingers. Measurements were made of finger-tip velocity, finger width, and finger-tip length. Non-dimensional forms of the measured variables are analyzed relative to the independent parameters, flow rate and gravitational gradient.

  15. Effect of changes in separatrix magnetic geometry on divertor behaviour in DIII-D

    NASA Astrophysics Data System (ADS)

    Petrie, T. W.; Canik, J. M.; Lasnier, C. J.; Leonard, A. W.; Mahdavi, M. A.; Watkins, J. G.; Fenstermacher, M. E.; Ferron, J. R.; Groebner, R. J.; Hill, D. N.; Hyatt, A. W.; Holcomb, C. T.; Luce, T. C.; Makowski, M.; Moyer, R. A.; Osborne, T. E.; Stangeby, P. C.

    2013-11-01

    Results and interpretation of recent experiments on DIII-D designed to evaluate divertor geometries favourable for radiative heat dispersal are presented. Two approaches examined here involved lengthening the parallel connection in the scrape-off layer, L‖, and increasing the radius of the outer divertor separatrix strike point, ROSP, with the goal of reducing target temperature, TTAR, and increasing target density, nTAR. From one-dimensional (1D) two-point modelling based on conducted parallel heat flux, it is expected that: n_{TAR} \\propto R_{OSP}^{2} L_{\\parallel}^{6/7} n_{SEP}^{3} and T_{TAR} \\propto R_{OSP}^{-2} L_{\\parallel}^{{-4}/7} n_{SEP}^{-2} , where nSEP is the midplane separatrix density. These scalings suggest that conditions conducive to a radiative divertor solution can be achieved at low nSEP by increasing either ROSP or L‖. Our data are consistent with the above L‖ scalings. On the other hand, the observed dependence of nTAR and TTAR on ROSP displayed a more complex behaviour, under certain conditions deviating from the above scalings. Our analysis indicates that deviations from the ROSP scaling were due to the presence of convected heat flux, driven by escaping neutrals, in the more open configurations of the larger ROSP cases. A comparison of ‘open’ versus ‘closed’ divertor configurations for the H-mode plasmas in this study show that the ‘closed’ case provides at least 30% reduction in the peaked heat flux at common density with the ‘open’ case and partial divertor detachment at lower plasma density.

  16. Assessment of erosion and surface tritium inventory issues for the ITER divertor

    SciTech Connect

    Brooks, J.N.; Causey, R.; Federici, G.; Ruzic, D.N.

    1996-08-01

    The authors analyzed sputtering erosion and tritium codeposition for the ITER vertical target divertor design using erosion and plasma codes (WBC/REDEP/DEGAS+) coupled to available materials data. Computations were made for a beryllium, carbon, and tungsten coated divertor plate, and for three edged plasma regimes. New data on tritium codeposition in beryllium was obtained with the TPE facility. This shows codeposited H/Be ratios of the order of 10% for surface temperatures {le} 300 C, beryllium thereby being similar to carbon in this respect. Hydrocarbon transport calculations show significant loss (10--20%) of chemically sputtered carbon for detached conditions (T{sub e} {approx} 1 eV at the divertor), compared to essentially no loss (100% redeposition) for higher temperature plasmas. Calculations also show a high, non-thermal, D-T molecular flux for detached conditions. Tritium codeposition rates for carbon are very high for detached conditions ({approximately} 20g-T/1000 s discharge), due to buildup of chemically sputtered carbon on relatively cold surfaces of the divertor cassette. Codeposition is lower ({approximately} 10X) for higher edge temperatures ({approximately} 8--30 eV) and is primarily due to divertor plate buildup of physically sputtered carbon. Peak net erosion rates for carbon are of order 30 cm/burn-yr. Erosion and codeposition rates for beryllium are much lower than for carbon at detached conditions, but are similar to carbon for the higher temperatures. Both erosion and tritium codeposition are essentially nil for tungsten for the regimes studied.

  17. Viscous fingering with partially miscible fluids

    NASA Astrophysics Data System (ADS)

    Fu, X.; Cueto-Felgueroso, L.; Juanes, R.

    2015-12-01

    When a less viscous fluid displaces a more viscous fluid, the contrast in viscosity destabilizes the interface between the two fluids, leading to the formation of fingers. Experimental and numerical studies of viscous fingering have focused on fluids that are either fully miscible (e.g. water and glycerol) or perfectly immiscible (e.g. water and oil). In practice, however, the miscibility of two fluids can change appreciably with temperature and pressure, and often falls into the case of partial miscibility, where two fluids have limited solubility in each other (e.g. CO2 and water). Following our recent work for miscible systems (Jha et al., PRL 2011, 2013) and immiscible systems (Cueto-Felgueroso and Juanes, PRL 2012, JFM 2014), here we propose a phase-field model for fluid-fluid displacements in a porous medium, when the two fluids have limited (but nonzero) solubility in one another. In our model, partial miscibility is characterized through the design of the thermodynamic free energy of the two-fluid system. We express the model in dimensionless form and elucidate the key dimensionless groups that control the behavior of the system. We present high-resolution numerical simulations of the model applied to the viscous fingering problem. On one hand, we demonstrate the effect of partial miscibility on the hydrodynamic instability. On the other, we elucidate the role of the degree of fingering on the rate of mutual fluid dissolution. Figure caption: final snapshots in simulations of viscous fingering with a two-fluid system mimicking that of CO2 and water. The colormap corresponds to the concentration of CO2. A band of less viscous gas phase rich in CO2 (red) displaces through the more viscous liquid phase that is undersaturated with CO2 (blue). At the fluid interface, an exchange of CO2 occurs as a result of local chemical potentials that drives the system towards thermodynamic equilibrium. This results in a shrinkage of gas phase as well as a local increase in

  18. The role of fingers in number processing in young children

    PubMed Central

    Lafay, Anne; Thevenot, Catherine; Castel, Caroline; Fayol, Michel

    2013-01-01

    The aim of the present study was to investigate the relationship between finger counting and numerical processing in 4–7-year-old children. Children were assessed on a variety of numerical tasks and we examined the correlations between their rates of success and their frequency of finger use in a counting task. We showed that children's performance on finger pattern comparison and identification tasks did not correlate with the frequency of finger use. However, this last variable correlated with the percentages of correct responses in an enumeration task (i.e., Give-N task), even when the age of children was entered as a covariate in the analysis. Despite this correlation, we showed that some children who never used their fingers in the counting task were able to perform optimally in the enumeration task. Overall, our results support the conclusion that finger counting is useful but not necessary to develop accurate symbolic numerical skills. Moreover, our results suggest that the use of fingers in a counting task is related to the ability of children in a dynamic enumeration task but not to static tasks involving recognition or comparison of finger patterns. Therefore, it could be that the link between fingers and numbers remain circumscribed to counting tasks and do not extent to static finger montring situations. PMID:23908643

  19. The role of fingers in number processing in young children.

    PubMed

    Lafay, Anne; Thevenot, Catherine; Castel, Caroline; Fayol, Michel

    2013-01-01

    The aim of the present study was to investigate the relationship between finger counting and numerical processing in 4-7-year-old children. Children were assessed on a variety of numerical tasks and we examined the correlations between their rates of success and their frequency of finger use in a counting task. We showed that children's performance on finger pattern comparison and identification tasks did not correlate with the frequency of finger use. However, this last variable correlated with the percentages of correct responses in an enumeration task (i.e., Give-N task), even when the age of children was entered as a covariate in the analysis. Despite this correlation, we showed that some children who never used their fingers in the counting task were able to perform optimally in the enumeration task. Overall, our results support the conclusion that finger counting is useful but not necessary to develop accurate symbolic numerical skills. Moreover, our results suggest that the use of fingers in a counting task is related to the ability of children in a dynamic enumeration task but not to static tasks involving recognition or comparison of finger patterns. Therefore, it could be that the link between fingers and numbers remain circumscribed to counting tasks and do not extent to static finger montring situations. PMID:23908643

  20. Recent Progress in the NSTX/NSTX-U Lithium Program and Prospects for Reactor-Relevant Liquid-Lithium Based Divertor Development

    SciTech Connect

    M. Ono, et al.

    2012-10-27

    Developing a reactor compatible divertor has been identified as a particularly challenging technology problem for magnetic confinement fusion. While tungsten has been identified as the most attractive solid divertor material, the NSTX/NSTX-U lithium (Li) program is investigating the viability of liquid lithium (LL) as a potential reactor compatible divertor plasma facing component (PFC) . In the near term, operation in NSTX-U is projected to provide reactor-like divertor heat loads < 40 MW/m^2 for 5 s. During the most recent NSTX campaign, ~ 0.85 kg of Li was evaporated onto the NSTX PFCs where a ~50% reduction in heat load on the Liquid Lithium Divertor (LLD) was observed, attributable to enhanced divertor bolometric radiation. This reduced divertor heat flux through radiation observed in the NSTX LLD experiment is consistent with the results from other lithium experiments and calculations. These results motivate an LL-based closed radiative divertor concept proposed here for NSTX-U and fusion reactors. With an LL coating, the Li is evaporated from the divertor strike point surface due to the intense heat. The evaporated Li is readily ionized by the plasma due to its low ionization energies, and the ionized Li ions can radiate strongly, resulting in a significant reduction in the divertor heat flux. Due to the rapid plasma transport in divertor plasma, the radiation values can be significantly enhanced up to ~ 11 MJ/cc of LL. This radiative process has the desired function of spreading the focused divertor heat load to the entire divertor chamber facilitating the divertor heat removal. The LL divertor surface can also provide a "sacrificial" surface to protect the substrate solid material from transient high heat flux such as the ones caused by the ELMs. The closed radiative LLD concept has the advantages of providing some degree of partition in terms of plasma disruption forces on the LL, Li particle divertor retention, and strong divertor pumping action from the

  1. FINGER INTERACTION IN A THREE-DIMENSIONAL PRESSING TASK

    PubMed Central

    Kapur, Shweta; Friedman, Jason; Zatsiorsky, Vladimir M.; Latash, Mark L.

    2010-01-01

    Accurate control of forces produced by the fingers is essential for performing object manipulation. This study examines the indices of finger interaction when accurate time profiles of force are produced in different directions, while using one of the fingers or all four fingers of the hand. We hypothesized that patterns of unintended force production among shear force components may involve features not observed in the earlier studies of vertical force production. In particular, we expected to see unintended forces generated by non-task fingers not in the direction on the instructed force but in the opposite direction as well as substantial force production in directions orthogonal to the instructed direction. We also tested a hypothesis that multi-finger synergies, quantified using the framework of the uncontrolled manifold hypothesis, will help reduce across-trials variance of both total force magnitude and direction. Young, healthy subjects were required to produce accurate ramps of force in five different directions by pressing on force sensors with the fingers of the right (dominant) hand. The index finger induced the smallest unintended forces in non-task fingers. The little finger showed the smallest unintended forces when it was a non-task finger. Task fingers showed substantial force production in directions orthogonal to the intended force direction. During four-finger tasks, individual force vectors typically pointed off the task direction, with these deviations nearly perfectly matched to produce a resultant force in the task direction. Multi-finger synergy indices reflected strong co-variation in the space of finger modes (commands to fingers) that reduced variability of the total force magnitude and direction across trials. The synergy indices increased in magnitude over the first 30% of the trial time and then stayed at a nearly constant level. The synergy index for stabilization of total force magnitude was higher for shear force components as

  2. Experiments of periodic forcing of Saffman-Taylor fingers

    NASA Astrophysics Data System (ADS)

    Torralba, M.; Ortín, J.; Hernández-Machado, A.; Poiré, E. Corvera

    2008-03-01

    We report on an experimental study of long normal Saffman-Taylor fingers subject to periodic forcing. The sides of the finger develop a low amplitude, long wavelength instability. We discuss the finger response in stationary and nonstationary situations, as well as the dynamics towards the stationary states. The response frequency of the instability increases with forcing frequency at low forcing frequencies, while, remarkably, it becomes independent of forcing frequency at large forcing frequencies. This implies a process of wavelength selection. These observations are in good agreement with previous numerical results reported in [Ledesma-Aguilar , Phys. Rev. E 71, 016312 (2005)]. We also study the average value of the finger width, and its fluctuations, as a function of forcing frequency. The average finger width is always smaller than the width of the steady-state finger. Fluctuations have a nonmonotonic behavior with a maximum at a particular frequency.

  3. Finger agnosia and cognitive deficits in patients with Alzheimer's disease.

    PubMed

    Davis, Andrew S; Trotter, Jeffrey S; Hertza, Jeremy; Bell, Christopher D; Dean, Raymond S

    2012-01-01

    The purpose of this study was to examine the presence of finger agnosia in patients with Alzheimer's disease (AD) and to determine if level of finger agnosia was related to cognitive impairment. Finger agnosia is a sensitive measure of cerebral impairment and is associated with neurofunctional areas implicated in AD. Using a standardized and norm-referenced approach, results indicated that patients with AD evidenced significantly decreased performance on tests of bilateral finger agnosia compared with healthy age-matched controls. Finger agnosia was predictive of cognitive dysfunction on four of seven domains, including: Crystallized Language, Fluid Processing, Associative Learning, and Processing Speed. Results suggest that measures of finger agnosia, a short and simple test, may be useful in the early detection of AD.

  4. Torque Control of Underactuated Tendon-driven Robotic Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Ihrke, Chris A. (Inventor); Reiland, Matthew J. (Inventor); Wampler, Charles W. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Bridgwater, Lyndon (Inventor)

    2013-01-01

    A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

  5. Finger velocities in the lifting Hele-Shaw cell

    NASA Astrophysics Data System (ADS)

    Kabiraj, Subrata K.; Tarafdar, Sujata

    2003-10-01

    Velocities of viscous fingers growing in a lifting Hele-Shaw cell are studied. The plates are separated by a pneumatic cylinder arrangement exerting a constant force. It is observed that with air invading a non-Newtonian oil-paint, finger velocities show an anomalous behaviour, with a rapid growth towards the end of the process. The correlation coefficient between neighbouring fingers shows the dominant modes selected as the pattern develops.

  6. Discrete families of Saffman-Taylor fingers with exotic shapes

    NASA Astrophysics Data System (ADS)

    Gardiner, Bennett P. J.; McCue, Scott W.; Moroney, Timothy J.

    The mathematical problem of determining the shape of a steadily propagating Saffman-Taylor finger in a rectangular Hele-Shaw cell is known to have a countably infinite number of solutions for each fixed surface tension value. For sufficiently large surface tension values, we find that fingers on higher solution branches are non-convex. The tips of the fingers have increasingly exotic shapes as the branch number increases.

  7. Upgrade of Langmuir probe diagnostic in ITER-like tungsten mono-block divertor on experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Xu, J. C.; Wang, L.; Xu, G. S.; Luo, G. N.; Yao, D. M.; Li, Q.; Cao, L.; Chen, L.; Zhang, W.; Liu, S. C.; Wang, H. Q.; Jia, M. N.; Feng, W.; Deng, G. Z.; Hu, L. Q.; Wan, B. N.; Li, J.; Sun, Y. W.; Guo, H. Y.

    2016-08-01

    In order to withstand rapid increase in particle and power impact onto the divertor and demonstrate the feasibility of the ITER design under long pulse operation, the upper divertor of the EAST tokamak has been upgraded to actively water-cooled, ITER-like tungsten mono-block structure since the 2014 campaign, which is the first attempt for ITER on the tokamak devices. Therefore, a new divertor Langmuir probe diagnostic system (DivLP) was designed and successfully upgraded on the tungsten divertor to obtain the plasma parameters in the divertor region such as electron temperature, electron density, particle and heat fluxes. More specifically, two identical triple probe arrays have been installed at two ports of different toroidal positions (112.5-deg separated toroidally), which can provide fundamental data to study the toroidal asymmetry of divertor power deposition and related 3-dimension (3D) physics, as induced by resonant magnetic perturbations, lower hybrid wave, and so on. The shape of graphite tip and fixed structure of the probe are designed according to the structure of the upper tungsten divertor. The ceramic support, small graphite tip, and proper connector installed make it possible to be successfully installed in the very narrow interval between the cassette body and tungsten mono-block, i.e., 13.5 mm. It was demonstrated during the 2014 and 2015 commissioning campaigns that the newly upgraded divertor Langmuir probe diagnostic system is successful. Representative experimental data are given and discussed for the DivLP measurements, then proving its availability and reliability.

  8. Divertor stray light analysis in JET-ILW and implications for the H-α diagnostic in ITER

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. B.; Neverov, V. S.; Stamp, M. F.; Alekseev, A. G.; Brezinsek, S.; Gorshkov, A. V.; von Hellermann, M.; Kadomtsev, M. B.; Kotov, V.; Kukushkin, A. S.; Levashova, M. G.; Lisgo, S. W.; Lisitsa, V. S.; Shurygin, V. A.; Veshchev, E.; Vukolov, D. K.; Vukolov, K. Yu.; JET EFDA Contributors

    2014-08-01

    We report on the first results for the spectrum of divertor stray light (DSL) and the signal-to-background ratio for D-α light emitted from the far SOL and divertor in JET in the recent ITER-like wall (ILW) campaign. The results support the expectation of a strong impact of DSL upon the H-alpha (and Visible Light) Spectroscopy Diagnostic in ITER.

  9. Upgrade of Langmuir probe diagnostic in ITER-like tungsten mono-block divertor on experimental advanced superconducting tokamak.

    PubMed

    Xu, J C; Wang, L; Xu, G S; Luo, G N; Yao, D M; Li, Q; Cao, L; Chen, L; Zhang, W; Liu, S C; Wang, H Q; Jia, M N; Feng, W; Deng, G Z; Hu, L Q; Wan, B N; Li, J; Sun, Y W; Guo, H Y

    2016-08-01

    In order to withstand rapid increase in particle and power impact onto the divertor and demonstrate the feasibility of the ITER design under long pulse operation, the upper divertor of the EAST tokamak has been upgraded to actively water-cooled, ITER-like tungsten mono-block structure since the 2014 campaign, which is the first attempt for ITER on the tokamak devices. Therefore, a new divertor Langmuir probe diagnostic system (DivLP) was designed and successfully upgraded on the tungsten divertor to obtain the plasma parameters in the divertor region such as electron temperature, electron density, particle and heat fluxes. More specifically, two identical triple probe arrays have been installed at two ports of different toroidal positions (112.5-deg separated toroidally), which can provide fundamental data to study the toroidal asymmetry of divertor power deposition and related 3-dimension (3D) physics, as induced by resonant magnetic perturbations, lower hybrid wave, and so on. The shape of graphite tip and fixed structure of the probe are designed according to the structure of the upper tungsten divertor. The ceramic support, small graphite tip, and proper connector installed make it possible to be successfully installed in the very narrow interval between the cassette body and tungsten mono-block, i.e., 13.5 mm. It was demonstrated during the 2014 and 2015 commissioning campaigns that the newly upgraded divertor Langmuir probe diagnostic system is successful. Representative experimental data are given and discussed for the DivLP measurements, then proving its availability and reliability. PMID:27587120

  10. Upgrade of Langmuir probe diagnostic in ITER-like tungsten mono-block divertor on experimental advanced superconducting tokamak.

    PubMed

    Xu, J C; Wang, L; Xu, G S; Luo, G N; Yao, D M; Li, Q; Cao, L; Chen, L; Zhang, W; Liu, S C; Wang, H Q; Jia, M N; Feng, W; Deng, G Z; Hu, L Q; Wan, B N; Li, J; Sun, Y W; Guo, H Y

    2016-08-01

    In order to withstand rapid increase in particle and power impact onto the divertor and demonstrate the feasibility of the ITER design under long pulse operation, the upper divertor of the EAST tokamak has been upgraded to actively water-cooled, ITER-like tungsten mono-block structure since the 2014 campaign, which is the first attempt for ITER on the tokamak devices. Therefore, a new divertor Langmuir probe diagnostic system (DivLP) was designed and successfully upgraded on the tungsten divertor to obtain the plasma parameters in the divertor region such as electron temperature, electron density, particle and heat fluxes. More specifically, two identical triple probe arrays have been installed at two ports of different toroidal positions (112.5-deg separated toroidally), which can provide fundamental data to study the toroidal asymmetry of divertor power deposition and related 3-dimension (3D) physics, as induced by resonant magnetic perturbations, lower hybrid wave, and so on. The shape of graphite tip and fixed structure of the probe are designed according to the structure of the upper tungsten divertor. The ceramic support, small graphite tip, and proper connector installed make it possible to be successfully installed in the very narrow interval between the cassette body and tungsten mono-block, i.e., 13.5 mm. It was demonstrated during the 2014 and 2015 commissioning campaigns that the newly upgraded divertor Langmuir probe diagnostic system is successful. Representative experimental data are given and discussed for the DivLP measurements, then proving its availability and reliability.

  11. Extrinsic versus intrinsic hand muscle dominance in finger flexion.

    PubMed

    Al-Sukaini, A; Singh, H P; Dias, J J

    2016-05-01

    This study aims to identify the patterns of dominance of extrinsic or intrinsic muscles in finger flexion during initiation of finger curl and mid-finger flexion. We recorded 82 hands of healthy individuals (18-74 years) while flexing their fingers and tracked the finger joint angles of the little finger using video motion tracking. A total of 57 hands (69.5%) were classified as extrinsic dominant, where the finger flexion was initiated and maintained at proximal interphalangeal and distal interphalangeal joints. A total of 25 (30.5%) were classified as intrinsic dominant, where the finger flexion was initiated and maintained at the metacarpophalangeal joint. The distribution of age, sex, dominance, handedness and body mass index was similar in the two groups. This knowledge may allow clinicians to develop more efficient rehabilitation regimes, since intrinsic dominant individuals would not initiate extrinsic muscle contraction till later in finger flexion, and might therefore be allowed limited early active motion. For extrinsic dominant individuals, by contrast, initial contraction of extrinsic muscles would place increased stress on the tendon repair site if early motion were permitted. PMID:26744509

  12. Acute finger injuries: part I. Tendons and ligaments.

    PubMed

    Leggit, Jeffrey C; Meko, Christian J

    2006-03-01

    Improper diagnosis and treatment of finger injuries can cause deformity and dysfunction over time. A basic understanding of the complex anatomy of the finger and of common tendon and ligament injury mechanisms can help physicians properly diagnose and treat finger injuries. Evaluation includes a general musculoskeletal examination as well as radiography (oblique, anteroposterior, and true lateral views). Splinting and taping are effective treatments for tendon and ligament injuries. Treatment should restrict the motion of injured structures while allowing uninjured joints to remain mobile. Although family physicians are usually the first to evaluate patients with finger injuries, it is important to recognize when a referral is needed to ensure optimal outcomes.

  13. The design and development of a finger joint simulator.

    PubMed

    Joyce, Thomas J

    2016-05-01

    Artificial finger joints lack the long-term clinical success seen with hip and knee prostheses. In part, this can be explained by the challenges of rheumatoid arthritis, a progressive disease which attacks surrounding tissues as well as the joint itself. Therefore, the natural finger joints' biomechanics are adversely affected, and consequently, this imbalance due to subluxing forces further challenges any prosthesis. Many different designs of finger prosthesis have been offered over a period of greater than 50 years. Most of these designs have failed, and it is likely that many of these failures could have been identified had the prostheses been appropriately tested prior to implantation into patients. While finger joint simulators have been designed, arguably only those from a single centre have been able to reproduce clinical-type failures of the finger prostheses tested in them. This article describes the design and development of a finger simulator at Durham University, UK. It explains and justifies the engineering decisions made and thus the evolution of the finger simulator. In vitro results and their linkage to clinical-type failures are outlined to help to show the effectiveness of the simulator. Failures of finger implants in vivo continue to occur, and the need for appropriate in vitro testing of finger prostheses remains strong.

  14. Numerical Simulations and an Experimental Investigation of a Finger Seal

    NASA Technical Reports Server (NTRS)

    Braun, Minel; Pierson, Hazel; Li, H.; Dong, Dingeng

    2006-01-01

    Besides sealing, the other main goal of a successful finger seal design is to exhibit appropriate compliance to outside forces. The ability of the seal to ride or float along the rotor without rubbing or excessive heating is essential to the successful operation of the seal. The compliance of the finger must only occur in the radial plane; The seal needs to be as sturdy as possible in the axial direction. The compliant finger that moves radially outward with rotor growth and motion has to be able to ride the rotor back down as the rotor diameter recovers or the rotor moves "away". Thus there is an optimum stiffness for the finger.

  15. Finger-Vein Verification Based on Multi-Features Fusion

    PubMed Central

    Qin, Huafeng; Qin, Lan; Xue, Lian; He, Xiping; Yu, Chengbo; Liang, Xinyuan

    2013-01-01

    This paper presents a new scheme to improve the performance of finger-vein identification systems. Firstly, a vein pattern extraction method to extract the finger-vein shape and orientation features is proposed. Secondly, to accommodate the potential local and global variations at the same time, a region-based matching scheme is investigated by employing the Scale Invariant Feature Transform (SIFT) matching method. Finally, the finger-vein shape, orientation and SIFT features are combined to further enhance the performance. The experimental results on databases of 426 and 170 fingers demonstrate the consistent superiority of the proposed approach. PMID:24196433

  16. Finger-vein verification based on multi-features fusion.

    PubMed

    Qin, Huafeng; Qin, Lan; Xue, Lian; He, Xiping; Yu, Chengbo; Liang, Xinyuan

    2013-01-01

    This paper presents a new scheme to improve the performance of finger-vein identification systems. Firstly, a vein pattern extraction method to extract the finger-vein shape and orientation features is proposed. Secondly, to accommodate the potential local and global variations at the same time, a region-based matching scheme is investigated by employing the Scale Invariant Feature Transform (SIFT) matching method. Finally, the finger-vein shape, orientation and SIFT features are combined to further enhance the performance. The experimental results on databases of 426 and 170 fingers demonstrate the consistent superiority of the proposed approach.

  17. The design and development of a finger joint simulator.

    PubMed

    Joyce, Thomas J

    2016-05-01

    Artificial finger joints lack the long-term clinical success seen with hip and knee prostheses. In part, this can be explained by the challenges of rheumatoid arthritis, a progressive disease which attacks surrounding tissues as well as the joint itself. Therefore, the natural finger joints' biomechanics are adversely affected, and consequently, this imbalance due to subluxing forces further challenges any prosthesis. Many different designs of finger prosthesis have been offered over a period of greater than 50 years. Most of these designs have failed, and it is likely that many of these failures could have been identified had the prostheses been appropriately tested prior to implantation into patients. While finger joint simulators have been designed, arguably only those from a single centre have been able to reproduce clinical-type failures of the finger prostheses tested in them. This article describes the design and development of a finger simulator at Durham University, UK. It explains and justifies the engineering decisions made and thus the evolution of the finger simulator. In vitro results and their linkage to clinical-type failures are outlined to help to show the effectiveness of the simulator. Failures of finger implants in vivo continue to occur, and the need for appropriate in vitro testing of finger prostheses remains strong. PMID:26833697

  18. Stick-slip instability for viscous fingering in a gel

    NASA Astrophysics Data System (ADS)

    Puff, N.; Debrégeas, G.; di Meglio, J.-M.; Higgins, D.; Bonn, D.; Wagner, C.

    2002-05-01

    The growth dynamics of an air finger injected in a visco-elastic gel (a PVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the standard Saffman-Taylor instability, we observe—with increasing finger velocities—the existence of two new regimes: (a) a stick-slip regime for which the finger tip velocity oscillates between 2 different values, producing local pinching of the finger at regular intervals; (b) a "tadpole" regime where a fracture-type propagation is observed. A scaling argument is proposed to interpret the dependence of the stick-slip frequency with the measured rheological properties of the gel.

  19. Toward a Code for the Interactions of Zinc Fingers with DNA: Selection of Randomized Fingers Displayed on Phage

    NASA Astrophysics Data System (ADS)

    Choo, Yen; Klug, Aaron

    1994-11-01

    We have used two selection techniques to study sequence-specific DNA recognition by the zinc finger, a small, modular DNA-binding minidomain. We have chosen zinc fingers because they bind as independent modules and so can be linked together in a peptide designed to bind a predetermined DNA site. In this paper, we describe how a library of zinc fingers displayed on the surface of bacteriophage enables selection of fingers capable of binding to given DNA triplets. The amino acid sequences of selected fingers which bind the same triplet are compared to examine how sequence-specific DNA recognition occurs. Our results can be rationalized in terms of coded interactions between zinc fingers and DNA, involving base contacts from a few α-helical positions. In the paper following this one, we describe a complementary technique which confirms the identity of amino acids capable of DNA sequence discrimination from these positions.

  20. Self-consistent treatment of the sheath boundary conditions by introducing anisotropic ion temperatures and virtual divertor model

    NASA Astrophysics Data System (ADS)

    Togo, Satoshi; Takizuka, Tomonori; Nakamura, Makoto; Hoshino, Kazuo; Ibano, Kenzo; Lang, Tee Long; Ogawa, Yuichi

    2016-04-01

    One-dimensional SOL-divertor plasma fluid simulation code which considers anisotropy of ion temperature has been developed so as to deal with sheath theory self-consistently. In our fluid modeling, explicit use of boundary condition for Mach number M at divertor plate, e.g., M = 1, becomes unnecessary. In order to deal with the Bohm condition and the sheath heat transmission factors at divertor plate self-consistently, we introduced a virtual divertor (VD) model which sets an artificial region beyond divertor plates and artificial sinks for particle, momentum and energy there to model the effects of the sheath region in front of the divertor plate. Validity of our fluid model with VD model is confirmed by showing that simulation results agree well with those from a kinetic code regarding the Bohm condition, ion temperature anisotropy and supersonic flow. We also show that the strength of artificial sinks in VD region does not affect profiles in plasma region at least in the steady state and that sheath heat transmission factors can be adjusted to theoretical values by VD model. Validity of viscous flux is also investigated.

  1. Divertor Heat Flux Mitigation in High-Performance H-mode Plasmas in the National Spherical Torus Experiment.

    SciTech Connect

    Soukhanovskii, V A; Maingi, R; Gates, D; Menard, J; Paul, S F; Raman, R; Roquemore, A L; Bell, R E; Bush, C; Kaita, R

    2008-09-22

    Experiments conducted in high-performance 1.0-1.2 MA 6 MW NBI-heated H-mode plasmas with a high flux expansion radiative divertor in NSTX demonstrate that significant divertor peak heat flux reduction and access to detachment may be facilitated naturally in a highly-shaped spherical torus (ST) configuration. Improved plasma performance with high {beta}{sub p} = 15-25%, a high bootstrap current fraction f{sub BS} = 45-50%, longer plasma pulses, and an H-mode regime with smaller ELMs has been achieved in the lower single null configuration with higher-end elongation 2.2-2.4 and triangularity 0.6-0.8. Divertor peak heat fluxes were reduced from 6-12 MW/m{sup 2} to 0.5-2 MW/m{sup 2} in ELMy H-mode discharges using high magnetic flux expansion and partial detachment of the outer strike point at several D{sub 2} injection rates, while good core confinement and pedestal characteristics were maintained. The partially detached divertor regime was characterized by a 30-60% increase in divertor plasma radiation, a peak heat flux reduction by up to 70%, measured in a 10 cm radial zone, a five-fold increase in divertor neutral pressure, and a significant volume recombination rate increase.

  2. Cholinergic vasodilator mechanism in human fingers

    SciTech Connect

    Coffman, J.D.; Cohen, R.A.

    1987-03-01

    The effect of a cholinergic agonist and antagonist on finger blood flow (FBF) was studied in 10 normal subjects. Total finger blood flow was measured by venous occlusion, air plethysmography, and capillary blood flow (FCF) by the disappearance rate of a radio-isotope from a fingertip injection. Methacholine in doses of 10-80 ..mu..g/min was given by constant infusion via a brachial artery catheter. Average FBF and vascular resistance were not significantly affected. However, the half time (t/sub 1/2/) of the disappearance rate decreased from 50.8 +/- 13.4 to 11.1 +/- 1.5 min; a decrease occurred in all subjects. In seven subjects, atropine (0.2 mg) had no affect alone but inhibited the effect of methacholine on FCF and prevented the redness and sweating of the forearm and hand that occurs with this agent. This study demonstrates a muscarinic cholinergic vasodilator mechanism in the fingertip that uniquely increase capillary blood flow.

  3. Teleoperation of Robonaut Using Finger Tracking

    NASA Technical Reports Server (NTRS)

    Champoux, Rachel G.; Luo, Victor

    2012-01-01

    With the advent of new finger tracking systems, the idea of a more expressive and intuitive user interface is being explored and implemented. One practical application for this new kind of interface is that of teleoperating a robot. For humanoid robots, a finger tracking interface is required due to the level of complexity in a human-like hand, where a joystick isn't accurate. Moreover, for some tasks, using one's own hands allows the user to communicate their intentions more effectively than other input. The purpose of this project was to develop a natural user interface for someone to teleoperate a robot that is elsewhere. Specifically, this was designed to control Robonaut on the international space station to do tasks too dangerous and/or too trivial for human astronauts. This interface was developed by integrating and modifying 3Gear's software, which includes a library of gestures and the ability to track hands. The end result is an interface in which the user can manipulate objects in real time in the user interface. then, the information is relayed to a simulator, the stand in for Robonaut, at a slight delay.

  4. Lipid Gymnastics: Tethers and Fingers in membrane

    NASA Astrophysics Data System (ADS)

    Tayebi, Lobat; Miller, Gregory; Parikh, Atul

    2009-03-01

    A significant body of evidence now links local mesoscopic structure (e.g., shape and composition) of the cell membrane with its function; the mechanisms by which cellular membranes adopt the specific shapes remain poorly understood. Among all the different structures adopted by cellular membranes, the tubular shape is one of the most surprising one. While their formation is typically attributed to the reorganization of membrane cytoskeleton, many exceptions exist. We report the instantaneous formation of tubular membrane mesophases following the hydration under specific thermal conditions. The shapes emerge in a bimodal way where we have two distinct diameter ranges for tubes, ˜20μm and ˜1μm, namely fat fingers and narrow tethers. We study the roughening of hydrated drops of 3 lipids in 3 different spontaneous curvatures at various temp. and ionic strength to figure out the dominant effect in selection of tethers and fingers. Dynamics of the tubes are of particular interest where we observe four distinct steps of birth, coiling, uncoiling and retraction with different lifetime on different thermal condition. These dynamics appear to reflect interplay between membrane elasticity, surface adhesion, and thermal or hydrodynamic gradient.

  5. Turbulent mixing in a salt finger staircase

    SciTech Connect

    Marmorino, G.O. )

    1990-08-15

    Towed thermistor chain measurements are examined for patches of turbulent mixing occurring within salt finger interfaces in the Caribbean staircase (the Caribbean Sheets and Layers Transects (C-SALT) experimental area). Patches are identified as regions having short overturning internal waves, resembling Kelvin-Helmholtz billows, and higher-wave number, more random fluctuations. For a patch turbulent dissipation rate of {approx}2 {times} 10{sup {minus}8} W kg{sup {minus}1} (based on other C-SALT measurements and consistent with the observed billow heights of 2-5 m) and an observed patch occurrence of {approx}1%, the mean dissipation rate is {approx}2 {times} 10{sup {minus}10} W kg{sup {minus}1}. This amount of turbulence would increase the buoyancy flux of heat and salt by 10-20% over fluxes from fingers acting alone and would increase the flux ratio by about 10% to 0.83, close to the value inferred from conductivity-temperature-depth data by Schmitt et al. (1987).

  6. Rehabilitation for bilateral amputation of fingers

    USGS Publications Warehouse

    Stapanian, Martin A.; Stapanian, Adrienne M.P.; Staley, Keith E.

    2010-01-01

    We describe reconstructive surgeries, therapy, prostheses, and adaptations for a patient who experienced bilateral amputation of all five fingers of both hands through the proximal phalanges in January 1992. The patient made considerable progress in the use of his hands in the 10 mo after amputation, including nearly a 120% increase in the active range of flexion of metacarpophalangeal joints. In late 1992 and early 1993, the patient had "on-top plasty" surgeries, in which the index finger remnants were transferred onto the thumb stumps, performed on both hands. The increased web space and functional pinch resulting from these procedures made many tasks much easier. The patient and occupational therapists set challenging goals at all times. Moreover, the patient was actively involved in the design and fabrication of all prostheses and adaptations or he developed them himself. Although he was discharged from occupational therapy in 1997, the patient continues to actively find new solutions for prehension and grip strength 18 yr after amputation.

  7. 3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Xu, Y.; Ida, K.; Corre, Y.; Feng, Y.; Schmitz, O.; Frerichs, H.; Tabares, F. L.; Evans, T. E.; Coenen, J. W.; Liang, Y.; Bader, A.; Itoh, K.; Yamada, H.; Ghendrih, Ph.; Ciraolo, G.; Tafalla, D.; Lopez-Fraguas, A.; Guo, H. Y.; Cui, Z. Y.; Reiter, D.; Asakura, N.; Wenzel, U.; Morita, S.; Ohno, N.; Peterson, B. J.; Masuzaki, S.

    2015-10-01

    This paper assesses the three-dimensional (3D) effects of the edge magnetic field structure on divertor/scrape-off layer transport, based on an inter-machine comparison of experimental data and on the recent progress of 3D edge transport simulation. The 3D effects are elucidated as a consequence of competition between transports parallel (\\parallel ) and perpendicular (\\bot ) to the magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of the divertor density regime, impurity screening and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Parameterization to measure the 3D effects on the edge transport is attempted for the individual divertor functions. Based on the suggested key parameters, an operation domain of the 3D divertor configuration is discussed for future devices.

  8. Optimal circumference reduction of finger models for good prosthetic fit of a thimble-type prosthesis for distal finger amputations.

    PubMed

    Leow, M E; Prosthetist, C; Pho, R W

    2001-01-01

    The prosthetic fit of a thimble-type esthetic silicone prosthesis was retrospectively reviewed in 29 patients who were fitted following distal finger amputations. The aim was to correlate prosthetic fit with the magnitudes of circumference reduction in the finger models used to produce the prostheses and to identify the optimum reduction for the best outcome. A good fit is achieved primarily by making the prosthesis circumferentially smaller than the segment of the residual finger (residuum) over which it "cups". The percentage reduction in circumference of the finger model against the residuum model was calculated by dividing the difference in circumference between the residuum model and the finger model by the residuum model circumference and multiplying the result by 100. The computed percentage circumference reduction in the finger models ranged from small (1-3), moderate (5-7), to large (8-9). Twelve of 15 patients whose finger models had between one to three circumference reductions had a loose prosthetic fit. Only two of 14 patients who had a larger model circumference reduction of between five to nine had loose-fitting prostheses. Two of five patients who had eight to nine model circumference reduction had an uncomfortably tight prosthetic fit. A 5-7% circumference reduction in the finger model was shown in this study to best translate into good fit of a thimble-type prosthesis for distal finger amputations.

  9. Study of a water-cooled convective divertor prototype for the DEMO fusion reactor

    NASA Astrophysics Data System (ADS)

    Di Maio, P.; Oliveri, E.; Vella, G.

    2000-04-01

    The plasma facing components of a fusion power reactor have a large impact on the overall plant design, its performance and availability and on the cost of electricity. The present work concerns a study of feasibility for a water-cooled prototype of the convective divertor component of the DEMO fusion reactor. The study has been carried out in two steps. In the first one thermal-hydraulic and neutronic parametric analyses have been performed to find out the prototype optimized configuration. In the second step thermo-mechanical analyses have been carried out on the obtained configuration to investigate the potential and limits of the proposed prototype, with a particular reference to the maximum heat flux it can undergo without incoming both in critical heat flux and in mechanical stress limits. The results show that the proposed divertor prototype is able to safely withstand peak heat fluxes of 9 MW/m2.

  10. Retention property of deuterium for fuel recovery in divertor by using hydrogen storage material

    NASA Astrophysics Data System (ADS)

    Mera, Saori; Tonegawa, Akira; Matsumura, Yoshihito; Sato, Kohnosuke; Kawamura, Kazutaka

    2014-10-01

    Magnetic confinement fusion reactor by using Deuterium and Tritium of hydrogen isotope as fuels is suggested as one of the future energy source. Most fuels don't react and are exhausted out of fusion reactor. Especially, Tritium is radioisotope and rarely exists in nature, so fuels recovery is necessary. This poster presentation will explain about research new fuel recovery method by using hydrogen storage materials in divertor simulator TPD-Sheet IV. Samples are tungsten coated with titanium; tungsten of various thickness, and titanium films deposited by ion plating on tungsten substrates. The sample surface temperature is measured by radiation thermometer. Retention property of deuterium after deuterium plasma irradiation was examined with thermal desorption spectroscopy (TDS). As a result, the TDS measurement shows that deuterium is retained in titanium. Therefore, Titanium as a hydrogen storage material expects to be possible to use separating and recovering fuel particles in divertor.

  11. End loss analyzer system for measurements of plasma flux at the C-2U divertor electrode

    NASA Astrophysics Data System (ADS)

    Griswold, M. E.; Korepanov, S.; Thompson, M. C.

    2016-11-01

    An end loss analyzer system consisting of electrostatic, gridded retarding-potential analyzers and pyroelectric crystal bolometers was developed to characterize the plasma loss along open field lines to the divertors of C-2U. The system measures the current and energy distribution of escaping ions as well as the total power flux to enable calculation of the energy lost per escaping electron/ion pair. Special care was taken in the construction of the analyzer elements so that they can be directly mounted to the divertor electrode. An attenuation plate at the entrance to the gridded retarding-potential analyzer reduces plasma density by a factor of 60 to prevent space charge limitations inside the device, without sacrificing its angular acceptance of ions. In addition, all of the electronics for the measurement are isolated from ground so that they can float to the bias potential of the electrode, 2 kV below ground.

  12. Free-boundary ideal MHD stability of W7-X divertor equilibria

    NASA Astrophysics Data System (ADS)

    Nührenberg, C.

    2016-07-01

    Plasma configurations describing the stellarator experiment Wendelstein 7-X (W7-X) are computationally established taking into account the geometry of the test-divertor unit and the high-heat-flux divertor which will be installed in the vacuum chamber of the device (Gasparotto et al 2014 Fusion Eng. Des. 89 2121). These plasma equilibria are computationally studied for their global ideal magnetohydrodynamic (MHD) stability properties. Results from the ideal MHD stability code cas3d (Nührenberg 1996 Phys. Plasmas 3 2401), stability limits, spatial structures and growth rates are presented for free-boundary perturbations. The work focusses on the exploration of MHD unstable regions of the W7-X configuration space, thereby providing information for future experiments in W7-X aiming at an assessment of the role of ideal MHD in stellarator confinement.

  13. A 250 GHz microwave interferometer for divertor experiments on DIII-D

    SciTech Connect

    James, R.A.; Nilson, D.G.; Stever, R.D.; Hill, D.N.; Casper, T.A.

    1994-01-31

    A new 250 GHz, two-frequency microwave interferometer system has been developed to diagnose divertor plasmas on DIII-D. This diagnostic will measure the line-averaged density across both the inner and outer, lower divertor legs. With a cut-off density of over 7 {times} 10{sup 14} cm{sup {minus}3}, temporal measurements of ELMs, MARFs and plasma detachment are expected. The outer leg system will use a double pass method while the inner leg system will be single pass. Two special 3D carbon composite tiles are used, one to protect the microwave antennas mounted directly under the strike point and the other as the outer leg reflecting surface. Performance, design constraints, and the thermalmechanical design of the 3D carbon composite tiles are discussed.

  14. Upgrade of the infrared camera diagnostics for the JET ITER-like wall divertor

    SciTech Connect

    Balboa, I.; Arnoux, G.; Kinna, D.; Thomas, P. D.; Morlock, C.; Kruezi, U.; Sergienko, G.; Rack, M.; Collaboration: JET EFDA Contributors

    2012-10-15

    For the new ITER-like wall at JET, two new infrared diagnostics (KL9B, KL3B) have been installed. These diagnostics can operate between 3.5 and 5 {mu}m and up to sampling frequencies of {approx}20 kHz. KL9B and KL3B image the horizontal and vertical tiles of the divertor. The divertor tiles are tungsten coated carbon fiber composite except the central tile which is bulk tungsten and consists of lamella segments. The thermal emission between lamellae affects the surface temperature measurement and therefore KL9A has been upgraded to achieve a higher spatial resolution (by a factor of 2). A technical description of KL9A, KL9B, and KL3B and cross correlation with a near infrared camera and a two-color pyrometer is presented.

  15. Modeling of ultra-high recycling divertors with the PLANET code

    SciTech Connect

    Petravic, M.

    1993-07-01

    The handling of power carried by the charged particles into the scrape-off layer of a tokamak reactor remains a major obstacle for its continuous and reliable operation. Ways of reducing this power through radiation have been studied numerically using fluid models for both the plasma and neutral gas. A new model for the combined plasma and neutral gas 2-D transport capable of simultaneously representing regions of fully-ionized plasma, partially ionized plasma, and pure neutral gas has been assembled and implemented in the PLANET code. Divertor plasma temperatures of just below 1 eV have been achieved in a pure hydrogen plasma, resulting in an ionization-free region together with ionization and recombination fronts detached from the material walls. In this regime energy reaches the walls almost exclusively in the form of radiation which, in principle, solves the divertor heat load problems.

  16. Upgrade of the infrared camera diagnostics for the JET ITER-like wall divertor.

    PubMed

    Balboa, I; Arnoux, G; Eich, T; Sieglin, B; Devaux, S; Zeidner, W; Morlock, C; Kruezi, U; Sergienko, G; Kinna, D; Thomas, P D; Rack, M

    2012-10-01

    For the new ITER-like wall at JET, two new infrared diagnostics (KL9B, KL3B) have been installed. These diagnostics can operate between 3.5 and 5 μm and up to sampling frequencies of ∼20 kHz. KL9B and KL3B image the horizontal and vertical tiles of the divertor. The divertor tiles are tungsten coated carbon fiber composite except the central tile which is bulk tungsten and consists of lamella segments. The thermal emission between lamellae affects the surface temperature measurement and therefore KL9A has been upgraded to achieve a higher spatial resolution (by a factor of 2). A technical description of KL9A, KL9B, and KL3B and cross correlation with a near infrared camera and a two-color pyrometer is presented.

  17. Observation of Non-Maxwellian Electron Distributions in th e NSTX Divertor

    SciTech Connect

    M.A. Jaworski, et. al.

    2013-03-07

    The scrape-off layer plasma at the tokamak region is characterized by open field lines and often contains large variations in plasma properties along these field-lines. Proper characterization of local plasma conditions is critical to assessing plasma-material interaction processes occuring at the target. Langmuir probes are frequently employed in tokamak divertors but are challenging to interpretation. A kinetic interpretation for Langmuir probes in NSTX has yielded non-Maxwellian electron distributions in the divertor characterized by cool bulk populations and energetic tail populations with temperatures of 2-4 times the bulk. Spectroscopic analysis and modeling confirms the bulk plasma temperature and density which can only be obtained with the kinetic interpretation

  18. The development of in-situ calibration method for divertor IR thermography in ITER

    SciTech Connect

    Takeuchi, M.; Sugie, T.; Ogawa, H.; Takeyama, S.; Itami, K.

    2014-08-21

    For the development of the calibration method of the emissivity in IR light on the divertor plate in ITER divertor IR thermography system, the laboratory experiments have been performed by using IR instruments. The calibration of the IR camera was performed by the plane black body in the temperature of 100–600 degC. The radiances of the tungsten heated by 280 degC were measured by the IR camera without filter (2.5–5.1 μm) and with filter (2.95 μm, 4.67 μm). The preliminary data of the scattered light of the laser of 3.34 μm that injected into the tungsten were acquired.

  19. Study of a Water-Cooled Convective Divertor Prototype for the DEMO Fusion Reactor

    SciTech Connect

    P. Di Maio; E. Oliveri; G. Vella

    2000-12-31

    The plasma facing components of a fusion power reactor have a large impact on the overall plant design, its performance and availability and on the cost of electricity. The present work concerns a study of feasibility for a water-cooled prototype of the convective divertor component of the DEMO fusion reactor. The study has been carried out in two steps. In the first one thermal-hydraulic and neutronic parametric analyses have been performed to find out the prototype optimized configuration. In the second step thermo-mechanical analyses have been carried out on the obtained configuration to investigate the potential and limits of the proposed prototype, with a particular reference to the maximum heat flux it can undergo without incoming both in critical heat flux and in mechanical stress limits. the results show that the proposed divertor prototype is able to safely withstand peak heat fluxes of 9 MW/m{sup 2}.

  20. High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions

    SciTech Connect

    Kallman, J.; Jaworski, M. A.; Kaita, R.; Kugel, H.; Gray, T. K.

    2010-01-01

    A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1-5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is similar to 1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.

  1. High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions.

    PubMed

    Kallman, J; Jaworski, M A; Kaita, R; Kugel, H; Gray, T K

    2010-10-01

    A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1-5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is ∼1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.

  2. High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions

    SciTech Connect

    Kallman, J.; Jaworski, M. A.; Kaita, R.; Kugel, H.; Gray, T. K.

    2010-10-15

    A high density Langmuir probe array has been developed for measurements of scrape-off layer parameters in NSTX. Relevant scale lengths for heat and particle fluxes are 1-5 cm. Transient edge plasma events can occur on a time scale of several milliseconds, and the duration of a typical plasma discharge is {approx}1 s. The array consists of 99 individual electrodes arranged in three parallel radial rows to allow both swept and triple-probe operation and is mounted in a carbon tile located in the lower outer divertor of NSTX between two segments of the newly installed liquid lithium divertor. Initial swept probe results tracking the outer strike point through probe flux measurements are presented.

  3. Upgrade of the infrared camera diagnostics for the JET ITER-like wall divertor.

    PubMed

    Balboa, I; Arnoux, G; Eich, T; Sieglin, B; Devaux, S; Zeidner, W; Morlock, C; Kruezi, U; Sergienko, G; Kinna, D; Thomas, P D; Rack, M

    2012-10-01

    For the new ITER-like wall at JET, two new infrared diagnostics (KL9B, KL3B) have been installed. These diagnostics can operate between 3.5 and 5 μm and up to sampling frequencies of ∼20 kHz. KL9B and KL3B image the horizontal and vertical tiles of the divertor. The divertor tiles are tungsten coated carbon fiber composite except the central tile which is bulk tungsten and consists of lamella segments. The thermal emission between lamellae affects the surface temperature measurement and therefore KL9A has been upgraded to achieve a higher spatial resolution (by a factor of 2). A technical description of KL9A, KL9B, and KL3B and cross correlation with a near infrared camera and a two-color pyrometer is presented. PMID:23130793

  4. Modelling salt finger formation using the Imperial College Ocean Model

    NASA Astrophysics Data System (ADS)

    MacTavish, F. P.; Cotter, C. J.; Piggott, M. D.

    2009-04-01

    We present numerical simulations of salt finger formation produced using the Imperial College Ocean Model (ICOM) which is a finite element model using adaptive meshing. Our aim is to validate the model against published data and to develop the capability to simulate salt finger formation using adaptive meshes. Salt fingering is a form of double-diffusion which occurs because heat diffuses more quickly than salt. When an area of warm, salty water overlies an area of colder, fresher water, an initial perturbation can lead to some of the water from the lower layer moving into the top layer. Its temperature then increases more quickly than its salinity, so that the water is less dense than its surroundings and it will rise up more. This process repeats to form salt fingers, with salt fingers also forming in the downward direction. Salt fingers play a role in oceanic mixing, in particular they are responsible for maintaining thermohaline staircases such as the C-SALT staircase which have been observed extensively, particularly in the tropics. The study of salt fingers could therefore improve our understanding of processes in the ocean, and inform the design of subgrid parameterisations in general circulation models. We used the salt finger formation test case of Oezgoekmen et al (1998) in order to validate ICOM. The formation of salt fingers is modelled by solving the Navier-Stokes equations for a two-dimensional rectangular area of Boussinesq fluid, beginning with two layers of water, the top warm and salty and the bottom cold and fresh, with parameters chosen to match the test case of Oezgoekmen et al (1998). The positions of the interfaces between the fingering layer and the mixed layers as well as the finger growth rate and the kinetic energy are plotted against time. The results are compared with those of Oezgoekmen et al (1998). We present results from structured meshes and preliminary results using adaptive meshing.

  5. A tangentially viewing VUV TV system for the DIII-D divertor

    SciTech Connect

    Nilson, D.G.; Ellis, R.; Fenstermacher, M.E.; Brewis, G.; Jalufka, N.

    1998-07-01

    A video camera system capable of imaging VUV emission in the 120--160 nm wavelength range, from the entire divertor region in the DIII-D tokamak, was designed. The new system has a tangential view of the divertor similar to an existing tangential camera system which has produced two dimensional maps of visible line emission (400--800 nm) from deuterium and carbon in the divertor region. However, the overwhelming fraction of the power radiated by these elements is emitted by resonance transitions in the ultraviolet, namely the C IV line at 155.0 nm and Ly-{alpha} line at 121.6 nm. To image the ultraviolet light with an angular view including the inner wall and outer bias ring in DIII-D, a 6-element optical system (f/8.9) was designed using a combination of reflective and refractive optics. This system will provide a spatial resolution of 1.2 cm in the object plane. An intermediate UV image formed in a secondary vacuum is converted to the visible by means of a phosphor plate and detected with a conventional CID camera (30 ms framing rate). A single MgF{sub 2} lens serves as the vacuum interface between the primary and secondary vacuums; a second lens must be inserted in the secondary vacuum to correct the focus at 155 nm. Using the same tomographic inversion method employed for the visible TV, they reconstruct the poloidal distribution of the UV divertor light. The grain size of the phosphor plate and the optical system aberrations limit the best focus spot size to 60 {micro}m at the CID plane. The optical system is designed to withstand 350 C vessel bakeout, 2 T magnetic fields, and disruption-induced accelerations of the vessel.

  6. Recent progress in the NSTX/NSTX-U lithium programme and prospects for reactor-relevant liquid-lithium based divertor development

    NASA Astrophysics Data System (ADS)

    Ono, M.; Jaworski, M. A.; Kaita, R.; Kugel, H. W.; Ahn, J.-W.; Allain, J. P.; Bell, M. G.; Bell, R. E.; Clayton, D. J.; Canik, J. M.; Ding, S.; Gerhardt, S.; Gray, T. K.; Guttenfelder, W.; Hirooka, Y.; Kallman, J.; Kaye, S.; Kumar, D.; LeBlanc, B. P.; Maingi, R.; Mansfield, D. K.; McLean, A.; Menard, J.; Mueller, D.; Nygren, R.; Paul, S.; Podesta, M.; Raman, R.; Ren, Y.; Sabbagh, S.; Scotti, F.; Skinner, C. H.; Soukhanovskii, V.; Surla, V.; Taylor, C. N.; Timberlake, J.; Zakharov, L. E.; the NSTX Research Team

    2013-11-01

    Developing a reactor-compatible divertor has been identified as a particularly challenging technology problem for magnetic confinement fusion. Application of lithium (Li) in NSTX resulted in improved H-mode confinement, H-mode power threshold reduction, and other plasma performance benefits. During the 2010 NSTX campaign, application of a relatively modest amount of Li (300 mg prior to the discharge) resulted in a ˜50% reduction in heat load on the liquid lithium divertor (LLD) attributable to enhanced divertor bolometric radiation. These promising Li results in NSTX and related modelling calculations motivated the radiative LLD concept proposed here. Li is evaporated from the liquid lithium (LL) coated divertor strike-point surface due to the intense heat flux. The evaporated Li is readily ionized by the plasma due to its low ionization energy, and the poor Li particle confinement near the divertor plate enables ionized Li ions to radiate strongly, resulting in a significant reduction in the divertor heat flux. This radiative process has the desired effect of spreading the localized divertor heat load to the rest of the divertor chamber wall surfaces, facilitating the divertor heat removal. The LL coating of divertor surfaces can also provide a ‘sacrificial’ protective layer to protect the substrate solid material from transient high heat flux such as the ones caused by the edge localized modes. By operating at lower temperature than the first wall, the LL covered large divertor chamber wall surfaces can serve as an effective particle pump for the entire reactor chamber, as impurities generally migrate towards lower temperature LL divertor surfaces. To maintain the LL purity, a closed LL loop system with a modest circulating capacity (e.g., ˜1 l s-1 for ˜1% level ‘impurities’) is envisioned for a steady-state 1 GW-electric class fusion power plant.

  7. Physics Design Requirements for the National Spherical Torus Experiment Liquid Lithium Divertor

    SciTech Connect

    Kugel, W.; Bell, M.; Berzak,L.; Brooks, A.; Ellis, R.; Gerhardt, S.; Harjes, H.; Kaita, R.; Kallman, J.; Maingi, R.; Majeski, R.; Mansfield, D.; Menard, J.; Nygren,R. E.; Soukhanovskii, V.; Stotler, D.; Wakeland, P.; Zakharov L. E.

    2008-09-26

    Recent NSTX high power divertor experiments have shown significant and recurring benefits of solid lithium coatings on PFC's to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. The next step in this work is installation of a liquid lithium divertor (LLD) to achieve density control for inductionless current drive capability (e.g., about a 15-25% ne decrease from present highest non-inductionless fraction discharges which often evolve toward the density limit, ne/nGW~1), to enable ne scan capability (x2) in the H-mode, to test the ability to operate at significantly lower density for future ST-CTF reactor designs (e.g., ne/nGW = 0.25), and eventually to investigate high heat-flux power handling (10 MW/m2) with longpulse discharges (>1.5s). The first step (LLD-1) physics design encompasses the desired plasma requirements, the experimental capabilities and conditions, power handling, radial location, pumping capability, operating temperature, lithium filling, MHD forces, and diagnostics for control and characterization.

  8. Detecting divertor damage during steady state operation of Wendelstein 7-X from thermographic measurements.

    PubMed

    Rodatos, A; Greuner, H; Jakubowski, M W; Boscary, J; Wurden, G A; Pedersen, T S; König, R

    2016-02-01

    Wendelstein 7-X (W7-X) aims to demonstrate the reactor capability of the stellarator concept, by creating plasmas with pulse lengths of up to 30 min at a heating power of up to 10 MW. The divertor plasma facing components will see convective steady state heat flux densities of up to 10 MW/m(2). These high heat flux target elements are actively cooled and are covered with carbon fibre reinforced carbon (CFC) as plasma facing material. The CFC is bonded to the CuCrZr cooling structure. Over the life time of the experiment this interface may weaken and cracks can occur, greatly reducing the heat conduction between the CFC tile and the cooling structure. Therefore, there is not only the need to monitor the divertor to prevent damage by overheating but also the need to detect these fatigue failures of the interface. A method is presented for an early detection of fatigue failures of the interface layer, solely by using the information delivered by the IR-cameras monitoring the divertor. This was developed and validated through experiments made with high heat flux target elements prior to installation in W7-X. PMID:26931848

  9. Measurements of non-axisymmetric effects in the DIII-D divertor

    SciTech Connect

    Evans, T.E,; Leonard, A.W.; Petrie, T.W.; Schaffer, M.J.; Lasnier, C.J.; Hill, D.N.; Fenstermacher, M.E.

    1994-07-01

    Non-stationary toroidal asymmetries are observed in the DIII-D divertor heat flux and scrape-off layer (SOL) currents. Using the present DIII-D diagnostics asymmetries are seen much less frequently in single-null H-modes (<5%) than in double-null H-modes (>50%). Divertor heat flux asymmetries are characterized by toroidal variations in the radial profile (i.e., multiple or bifurcated peaks at some toroidal locations and single peaks at others) while SOL currents sometimes have a strongly bipolar toroidal structure. SOL current asymmetries are particularly large during Edge Localized Modes (ELMs). In some cases heat flux variations of as much as a factor of two are seen. The measurements reported here indicate that these asymmetries are best described by a model in which non-axisymmetric radial magnetic perturbations create magnetic islands in the plasma boundary and scrape-off layer which then cause toroidal variation in the divertor heat flux and the scrape-off layer currents.

  10. Power exhaust in the snowflake divertor for L- and H-mode TCV tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Vijvers, W. A. J.; Canal, G. P.; Labit, B.; Reimerdes, H.; Tal, B.; Coda, S.; De Temmerman, G. C.; Duval, B. P.; Morgan, T. W.; Zielinski, J. J.; the TCV Team

    2014-02-01

    The snowflake (SF) divertor is a plasma configuration that may enable tokamak operation at high performance and lower peak heat loads on the plasma-facing components than a standard single-null divertor. This paper reports on the results of experiments performed on the TCV tokamak in both the low- and high-confinement regimes, wherein the divertor configuration was continuously varied between a standard single-null and a ‘SF-plus’, which features auxiliary strike points (SPs) in the private flux region of the primary separatrix. The measured edge properties show that, in L-mode, the fraction of the exhaust power reaching the additional SPs is small. During edge-localized modes, up to ˜20% of the exhausted energy is redistributed to the additional SPs even at an x-point separation of 0.6 times the plasma minor radius, thereby reducing the peak heat flux to the inner primary SP by a factor of 2-3. The observed behaviour is qualitatively consistent with a proposed model for enhanced cross-field transport through the SF's relatively large region of low poloidal field by instability-driven convection.

  11. The role of plasma response in divertor footprint modification by 3D fields in NSTX

    NASA Astrophysics Data System (ADS)

    Ahn, Joonwook; Kim, Kimin; Canal, Gustavo; Gan, Kaifu; Gray, Travis; McLean, Adam; Park, Jong-Kyu; Scotti, Filippo

    2015-11-01

    In NSTX, the divertor footprints of both heat and particle fluxes are found to be significantly modified by externally applied 3D magnetic perturbations. Striations on the divertor surface, indicating separatrix splitting and formation of magnetic lobes, are observed for both n = 1 and n = 3 perturbation fields. These striations can lead to localized heating of the divertor plates and to the re-attachment of detached plasmas, both of which have to be avoided in ITER for successful heat flux management. In this work, the role of plasma response on the formation of separatrix splitting has been investigated in the ideal framework by comparing measured heat and particle flux footprints with field line tracing calculations with and without contributions from the plasma response calculated by the ideal code IPEC. Simulations show that, n = 3 fields are slightly shielded by the plasma, with the measured helical pattern of striations in good agreement with the results from the vacuum approximation. The n = 1 fields are, however, significantly amplified by the plasma response, which provides a better agreement with the measurements. Resistive plasma response calculations by M3D-C1 are also in progress and the results will be compared with those from the ideal code IPEC. This work was supported by DoE Contracts: DE-AC05-00OR22725, DE-AC52-07NA27344 and DE-AC02-09CH11466.

  12. Plasma flow and electron losses in the expander divertor of FRC

    NASA Astrophysics Data System (ADS)

    Yushmanov, P.; Barnes, D.; Dettrick, S.; Gupta, S.; Ryutov, D.; Krasheninnikov, S.; Necas, A.; Putvinski, S.

    2014-10-01

    Expander divertor is planned to be used in the design of next generation FRC device. The main goal of magnetic field expansion is to decrease heat load on the target plates and slow down heat losses through electron channel. A comprehensive study of expander divertor physics is initiated in Tri Alpha. It started with revision of pre-sheath electrostatic potential formation in the expander using both analytic and numerical means. An adaptation of 3D code KSOL has been developed to analyze electron physics and electrostatic potential formation. Initial results are presented. The key issue of the study is the analysis of the interaction of plasma with neutrals. Presence of neutrals affects expander physics in several ways. First of all, charge exchange and ionization modify pattern of ion flow in the expander magnetic field. That changes plasma density profile and affects formation of pre-sheath electrostatic potential. Second, ionization (as well as secondary electron emission) creates population of cold electrons in the expander which flow into confinement vessel and enhance out-flux of hot electrons. Distribution of neutrals is calculated in realistic geometry of expander divertor and effect on electron losses is evaluated.

  13. Exposures of tungsten nanostructures to divertor plasmas in DIII-D

    DOE PAGES

    Rudakov, D. L.; Wong, C. P. C.; Doerner, R. P.; Wright, G. M.; Abrams, T.; Baldwin, M. J.; Boedo, J. A.; Briesemeister, A. R.; Chrobak, C. P.; Guo, H. Y.; et al

    2016-01-22

    Tungsten nanostructures (W-fuzz) prepared in the PISCES-A linear device have been found to survive direct exposure to divertor plasmas in DIII-D. W-fuzz was exposed in the lower divertor of DIII-D using the divertor material evaluation system. Two samples were exposed in lower single null (LSN) deuterium H-mode plasmas. The first sample was exposed in three discharges terminated by vertical displacement event disruptions, and the second in two discharges near the lowered X-point. More recently, three samples were exposed near the lower outer strike point in predominantly helium H-mode LSN plasmas. In all cases, the W-fuzz survived plasma exposure with littlemore » obvious damage except in the areas where unipolar arcing occurred. In conclusion, arcing is effective in W-fuzz removal, and it appears that surfaces covered with W-fuzz can be more prone to arcing than smooth W surfaces.« less

  14. Analysis of a multi-machine database on divertor heat fluxesa)

    NASA Astrophysics Data System (ADS)

    Makowski, M. A.; Elder, D.; Gray, T. K.; LaBombard, B.; Lasnier, C. J.; Leonard, A. W.; Maingi, R.; Osborne, T. H.; Stangeby, P. C.; Terry, J. L.; Watkins, J.

    2012-05-01

    A coordinated effort to measure divertor heat flux characteristics in fully attached, similarly shaped H-mode plasmas on C-Mod, DIII-D, and NSTX was carried out in 2010 in order to construct a predictive scaling relation applicable to next step devices including ITER, FNSF, and DEMO. Few published scaling laws are available and those that have been published were obtained under widely varying conditions and divertor geometries, leading to conflicting predictions for this critically important quantity. This study was designed to overcome these deficiencies. Analysis of the combined data set reveals that the primary dependence of the parallel heat flux width is robustly inverse with Ip, which all three tokamaks independently demonstrate. An improved Thomson scattering system on DIII-D has yielded very accurate scrape off layer (SOL) profile measurements from which tests of parallel transport models have been made. It is found that a flux-limited model agrees best with the data at all collisionalities, while a Spitzer resistivity model agrees at higher collisionality where it is more valid. The SOL profile measurements and divertor heat flux scaling are consistent with a heuristic drift based model as well as a critical gradient model.

  15. Attainment of high confinement in neutral beam heated divertor discharges in the PDX tokamak

    SciTech Connect

    Kaye, S.M.; Bell, M.; Bol, K.; Boyd, D.; Brau, K.; Buchenauer, D.; Budny, R.; Cavallo, A.; Couture, P.; Crowley, T.

    1983-11-01

    The PDX divertor configuration has recently been converted from an open to a closed geometry to inhibit the return of neutral gas from the divertor region to the main chamber. Since then, operation in a regime with high energy confinement in neutral beam heated discharges (ASDEX H-mode) has been routine over a wide range of operating conditions. These H-mode discharges are characterized by a sudden drop in divertor density and H/sub ..cap alpha../ emission and a spontaneous rise in main chamber plasma density during neutral beam injection. The confinement time is found to scale nearly linearly with plasma current, but it can be degraded due to either the presence of edge instabilities or heavy gas puffing. Detailed Thomson scattering temperature profiles show high values of Te near the plasma edge (approx. 450 eV) with sharp radial gradients (approx. 400 eV/cm) near the separatrix. Density profiles are broad and also exhibit steep gradients close to the separatrix.

  16. High heat flux Langmuir probe array for the DIII-D divertor plates

    SciTech Connect

    Watkins, J. G.; Nygren, R. E.; Taussig, D.; Boivin, R. L.; Mahdavi, M. A.

    2008-10-15

    Two modular arrays of Langmuir probes designed to handle a heat flux of up to 25 MW/m{sup 2} for 10 s exposures have been installed in the lower divertor target plates of the DIII-D tokamak. The 20 pyrolytic graphite probe tips have more than three times higher thermal conductivity and 16 times larger mass than the original DIII-D isotropic graphite probes. The probe tips have a fixed 12.5 deg. surface angle to distribute the heat flux more uniformly than the previous 6 mm diameter domed collectors and a symmetric 'rooftop' design to allow operation with reversed toroidal magnetic field. A large spring-loaded contact area improves heat conduction from each probe tip through a ceramic insulator into a cooled graphite divertor floor tile. The probe tips, brazed to molybdenum foil to ensure good electrical contact, are mounted in a ceramic tray for electrical isolation and reliable cable connections. The new probes are located 1.5 cm radially apart in a staggered arrangement near the entrance to the lower divertor pumping baffle and are linearly spaced 3 cm apart on the shelf above the in-vessel cryopump. Typical target plate profiles of J{sub sat}, T{sub e}, and V{sub f} with 4 mm spatial resolution are shown.

  17. Finite Element Modelling of Transport and Drift Effects in Tokamak Divertor and SOL.

    NASA Astrophysics Data System (ADS)

    Simard, M.; Marchand, R.; Stansfield, B. L.; Boucher, C.; Mailloux, J.; Gunn, J. P.

    1996-11-01

    A finite element code is used to simulate transport of a single-species plasma in the edge and divertor of a tokamak. The physical model is based on Braginskii's fluid equations for the conservation of particles, parallel momentum, ion and electron energy. In modelling recycling, transport of neutral density and energy is treated in the diffusion approximation. The electrostatic potential is obtained self-consistently from the charge conservation equation and from the generalized Ohm's law. In the transport equations, particle drifts (both E×B and diamagnetic) are included. Transport also accounts for a current flowing in the edge. Simulations with different types of boundary conditions, recently proposed in the literature, are considered and assessed. Comparisons are made between simulation and experimental results from TdeV. Particular attention is given to density and temperature profiles at the divertor plates, and to the plasma parallel velocity in the SOL with and without divertor plate biasing. Supported by the Government of Canada, Hydro-Québec and INRS

  18. Automated divertor target design by adjoint shape sensitivity analysis and a one-shot method

    SciTech Connect

    Dekeyser, W.; Reiter, D.; Baelmans, M.

    2014-12-01

    As magnetic confinement fusion progresses towards the development of first reactor-scale devices, computational tokamak divertor design is a topic of high priority. Presently, edge plasma codes are used in a forward approach, where magnetic field and divertor geometry are manually adjusted to meet design requirements. Due to the complex edge plasma flows and large number of design variables, this method is computationally very demanding. On the other hand, efficient optimization-based design strategies have been developed in computational aerodynamics and fluid mechanics. Such an optimization approach to divertor target shape design is elaborated in the present paper. A general formulation of the design problems is given, and conditions characterizing the optimal designs are formulated. Using a continuous adjoint framework, design sensitivities can be computed at a cost of only two edge plasma simulations, independent of the number of design variables. Furthermore, by using a one-shot method the entire optimization problem can be solved at an equivalent cost of only a few forward simulations. The methodology is applied to target shape design for uniform power load, in simplified edge plasma geometry.

  19. Detecting divertor damage during steady state operation of Wendelstein 7-X from thermographic measurements

    NASA Astrophysics Data System (ADS)

    Rodatos, A.; Greuner, H.; Jakubowski, M. W.; Boscary, J.; Wurden, G. A.; Pedersen, T. S.; König, R.

    2016-02-01

    Wendelstein 7-X (W7-X) aims to demonstrate the reactor capability of the stellarator concept, by creating plasmas with pulse lengths of up to 30 min at a heating power of up to 10 MW. The divertor plasma facing components will see convective steady state heat flux densities of up to 10 MW/m2. These high heat flux target elements are actively cooled and are covered with carbon fibre reinforced carbon (CFC) as plasma facing material. The CFC is bonded to the CuCrZr cooling structure. Over the life time of the experiment this interface may weaken and cracks can occur, greatly reducing the heat conduction between the CFC tile and the cooling structure. Therefore, there is not only the need to monitor the divertor to prevent damage by overheating but also the need to detect these fatigue failures of the interface. A method is presented for an early detection of fatigue failures of the interface layer, solely by using the information delivered by the IR-cameras monitoring the divertor. This was developed and validated through experiments made with high heat flux target elements prior to installation in W7-X.

  20. Coordination of bowing and fingering in violin playing.

    PubMed

    Baader, Andreas P; Kazennikov, Oleg; Wiesendanger, Mario

    2005-05-01

    Playing string instruments implies motor skills including asymmetrical interlimb coordination. How special is musical skill as compared to other bimanually coordinated, non-musical skillful performances? We succeeded for the first time to measure quantitatively bimanual coordination in violinists playing repeatedly a simple tone sequence. A motion analysis system was used to record finger and bow trajectories for assessing the temporal structure of finger-press, finger-lift (left hand), and bow stroke reversals (right arm). The main results were: (1) fingering consisted of serial and parallel (anticipatory) mechanisms; (2) synchronization between finger and bow actions varied from -12 ms to 60 ms, but these 'errors' were not perceived. The results suggest that (1) bow-finger synchronization varied by about 50 ms from perfect simultaneity, but without impairing auditory perception; (2) the temporal structure depends on a number of combinatorial mechanisms of bowing and fingering. These basic mechanisms were observed in all players, including all amateurs. The successful biomechanical measures of fingering and bowing open a vast practical field of assessing motor skills. Thus, objective assessment of larger groups of string players with varying musical proficiency, or of professional string players developing movement disorders, may be helpful in music education. PMID:15820650

  1. Toward a Phonetic Representation of Hand Configuration: The Fingers

    ERIC Educational Resources Information Center

    Johnson, Robert E.; Liddell, Scott K.

    2011-01-01

    In this article we describe a componential, articulatory approach to the phonetic description of the configuration of the four fingers. Abandoning the traditional holistic, perceptual approach, we propose a system of notational devices and distinctive features for the description of the four fingers proper (index, middle, ring, and pinky).…

  2. Index finger abnormalities in Simpson-Golabi-Behmel syndrome.

    PubMed

    Day, Ruth; Fryer, Alan

    2005-01-01

    Simpson-Golabi-Behmel syndrome (SGBS) is an X linked recessive overgrowth disorder in which digital abnormalities are a well-described aspect of the phenotype. We report a case with marked index finger hypoplasia and a congenital abnormality of the proximal phalanx and review the literature detailing index finger abnormalities in this condition.

  3. Rediscovering Ruth Faison Shaw and Her Finger-Painting Method

    ERIC Educational Resources Information Center

    Mayer, Veronica

    2005-01-01

    Ruth Faison Shaw was an art educator who developed a nontraditional educational perspective of teaching and a different vision about children's art. As such, she is considered by some to be the initiator of finger-painting in America (The History of Art Education Timeline 1930-1939, 2002.) Shaw developed the technique of finger-painting and a…

  4. Coordination of bowing and fingering in violin playing.

    PubMed

    Baader, Andreas P; Kazennikov, Oleg; Wiesendanger, Mario

    2005-05-01

    Playing string instruments implies motor skills including asymmetrical interlimb coordination. How special is musical skill as compared to other bimanually coordinated, non-musical skillful performances? We succeeded for the first time to measure quantitatively bimanual coordination in violinists playing repeatedly a simple tone sequence. A motion analysis system was used to record finger and bow trajectories for assessing the temporal structure of finger-press, finger-lift (left hand), and bow stroke reversals (right arm). The main results were: (1) fingering consisted of serial and parallel (anticipatory) mechanisms; (2) synchronization between finger and bow actions varied from -12 ms to 60 ms, but these 'errors' were not perceived. The results suggest that (1) bow-finger synchronization varied by about 50 ms from perfect simultaneity, but without impairing auditory perception; (2) the temporal structure depends on a number of combinatorial mechanisms of bowing and fingering. These basic mechanisms were observed in all players, including all amateurs. The successful biomechanical measures of fingering and bowing open a vast practical field of assessing motor skills. Thus, objective assessment of larger groups of string players with varying musical proficiency, or of professional string players developing movement disorders, may be helpful in music education.

  5. Robust Finger Vein ROI Localization Based on Flexible Segmentation

    PubMed Central

    Lu, Yu; Xie, Shan Juan; Yoon, Sook; Yang, Jucheng; Park, Dong Sun

    2013-01-01

    Finger veins have been proved to be an effective biometric for personal identification in the recent years. However, finger vein images are easily affected by influences such as image translation, orientation, scale, scattering, finger structure, complicated background, uneven illumination, and collection posture. All these factors may contribute to inaccurate region of interest (ROI) definition, and so degrade the performance of finger vein identification system. To improve this problem, in this paper, we propose a finger vein ROI localization method that has high effectiveness and robustness against the above factors. The proposed method consists of a set of steps to localize ROIs accurately, namely segmentation, orientation correction, and ROI detection. Accurate finger region segmentation and correct calculated orientation can support each other to produce higher accuracy in localizing ROIs. Extensive experiments have been performed on the finger vein image database, MMCBNU_6000, to verify the robustness of the proposed method. The proposed method shows the segmentation accuracy of 100%. Furthermore, the average processing time of the proposed method is 22 ms for an acquired image, which satisfies the criterion of a real-time finger vein identification system. PMID:24284769

  6. Finger vein extraction using gradient normalization and principal curvature

    NASA Astrophysics Data System (ADS)

    Choi, Joon Hwan; Song, Wonseok; Kim, Taejeong; Lee, Seung-Rae; Kim, Hee Chan

    2009-02-01

    Finger vein authentication is a personal identification technology using finger vein images acquired by infrared imaging. It is one of the newest technologies in biometrics. Its main advantage over other biometrics is the low risk of forgery or theft, due to the fact that finger veins are not normally visible to others. Extracting finger vein patterns from infrared images is the most difficult part in finger vein authentication. Uneven illumination, varying tissues and bones, and changes in the physical conditions and the blood flow make the thickness and brightness of the same vein different in each acquisition. Accordingly, extracting finger veins at their accurate positions regardless of their thickness and brightness is necessary for accurate personal identification. For this purpose, we propose a new finger vein extraction method which is composed of gradient normalization, principal curvature calculation, and binarization. As local brightness variation has little effect on the curvature and as gradient normalization makes the curvature fairly uniform at vein pixels, our method effectively extracts finger vein patterns regardless of the vein thickness or brightness. In our experiment, the proposed method showed notable improvement as compared with the existing methods.

  7. Actinomycosis of Finger: Case Report and Review of the Literature

    PubMed Central

    Moghimi, Mansour; Zarch, Mojtaba Babaei

    2016-01-01

    Cutaneous actinomycosis of finger is very unusual, chronic granulomatous disease caused by a group of anaerobic or microaerophilic Gram-positive filamentous bacteria that normally colonize the mouth, colon and urogenital tract. Actinomycosis of finger is rare but clinically important condition that requires suitable evaluation for guiding appropriate therapy. We hereby report a case of cutaneous actinomycosis of the right finger- a rare site, in a 34-year-old female patient which underwent usual treatment of surgical excision. This patient complained of existence of a mass and tenderness in the pulp of right index finger. The X-ray of hand revealed no significant abnormality. The patient was treated successfully with surgical excision. Surgery detected five small nodules measuring 0.5 to 1 cm in size. Histopathologic examination of the biopsy from the lesions confirmed diagnosis of cutaneous actinomycosis. Here, we report a cutaneous actinomycosis in a 34-year-old female located in the index finger. PMID:27656447

  8. Isolated index finger palsy due to cortical infarction.

    PubMed

    Kawabata, Yuichi; Miyaji, Yosuke; Joki, Hideto; Seki, Syunsuke; Mori, Kentaro; Kamide, Tomoya; Tamase, Akira; Nomura, Motohiro; Kitamura, Yoshihisa; Tanaka, Fumiaki

    2014-01-01

    The case of an 86-year-old man presenting with isolated left index finger palsy caused by infarction on the lateral side of the right precentral knob is presented. Embolization from aortic atheroma was considered the cause of infarction. Cases with selective palsy of a particular group of fingers without sensory deficits due to cortical infarction of the precentral knob have been reported by several authors, and predominant weakness of radial-side fingers is known to be usually caused by laterally located infarction of the precentral knob. Among the previous reports, only 1 case involved isolated index finger palsy by an atypical, medially located infarction of the precentral knob in association with a concurrent nonrelated lesion. This is the first reported isolated index finger palsy caused by a single lateral precentral knob infarction.

  9. Dangers of neglect: partially embedded ring upon a finger.

    PubMed

    Kumar, Anand; Edwards, Huw; Lidder, Surjit; Mestha, Prabhakar

    2013-01-01

    Digital swelling is a common presentation in clinical practice. Patients presenting with swollen fingers to the emergency department will often have rings on their finger, which can be removed using a variety of simple non-operative techniques or by cutting the ring off and thus avoiding any long-term consequences. Very rarely, when there is a delay in presentation of these patients, serious consequences may proceed, including finger ischaemia, infection, tendon attrition or ultimately the need for surgical amputation. We present an unusual case of patient with psychiatric illness who presented late with a ring that had embedded upon the volar aspect of the index finger. The difficulties faced by the emergency care practitioners in such circumstances, the consequences of rings acting as a tourniquet and strategies for removal of rings on swollen fingers are highlighted.

  10. Active Finger Recognition from Surface EMG Signal Using Bayesian Filter

    NASA Astrophysics Data System (ADS)

    Araki, Nozomu; Hoashi, Yuki; Konishi, Yasuo; Mabuchi, Kunihiko; Ishigaki, Hiroyuki

    This paper proposed an active finger recognition method using Bayesian filter in order to control a myoelectric hand. We have previously proposed a finger joint angle estimation method based on measured surface electromyography (EMG) signals and a linear model. However, when we estimate 2 or more finger angles by this estimation method, the estimation angle of the inactive finger is not accurate. This is caused by interference of surface EMG signal. To solve this interference problem, we proposed active finger recognition method from the amplitude spectrum of surface EMG signal using Bayesian filter. To confirm the effectiveness of this recognition method, we developed a myoelectric hand simulator that implements proposed recognition algorithm and carried out real-time recognition experiment.

  11. [Thinking on acupuncture finger force in the acupuncture quantity study].

    PubMed

    Wang, Ya-Jing; Liu, Jian; Fan, Xiao-Nong; Meng, Zhi-Hong; Wang, Shu

    2012-09-01

    As an important link during the whole operation process of acupuncture, it is very necessary to launch quantity study closely related to acupuncture finger force in the acupuncture quantity study. After retrieval of related literatures on finger force during acupuncture in recent 20 years, it was found out that although some exploration on acupuncture finger force had been made, it was scattered and had no deep research, which pointed out it was a weak link in the acupuncture quantity study. So study of finger force should be paid attention to in acupuncture-moxibustion field, the level of theoretical and experimental research and development of measuring instrument on acupuncture finger force should be strengthened, the application of instrument should be expanded in teaching and scientific research areas, which could promote the modernization and internationalization of acupuncture and moxibustion better and faster.

  12. ADX: a high field, high power density, advanced divertor and RF tokamak

    NASA Astrophysics Data System (ADS)

    LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

    2015-05-01

    The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept

  13. Mechanics of finger-tip electronics

    PubMed Central

    Su, Yewang; Li, Rui; Cheng, Huanyu; Ying, Ming; Bonifas, Andrew P.; Hwang, Keh-Chih; Rogers, John A.; Huang, Yonggang

    2013-01-01

    Tactile sensors and electrotactile stimulators can provide important links between humans and virtual environments, through the sensation of touch. Soft materials, such as low modulus silicones, are attractive as platforms and support matrices for arrays sensors and actuators that laminate directly onto the fingertips. Analytic models for the mechanics of three dimensional, form-fitting finger cuffs based on such designs are presented here, along with quantitative validation using the finite element method. The results indicate that the maximum strains in the silicone and the embedded devices are inversely proportional to the square root of radius of curvature of the cuff. These and other findings can be useful in formulating designs for these and related classes of body-worn, three dimensional devices. PMID:24273338

  14. Surface Tension and Fingering of Miscible Interfaces

    NASA Technical Reports Server (NTRS)

    Abib, Mohammed; Liu, Jian-Bang; Ronney, Paul D.

    1999-01-01

    Experiments on miscible, buoyantly unstable reaction-diffusion fronts and non-reacting displacement fronts in Hele-Shaw cells show a fingering-type instability whose wavelengths (lambda*) are consistent with an interfacial tension (sigma) at the front caused by the change in chemical composition, even though the solutions are miscible in all proportions. In conjunction with the Saffman-Taylor model, the relation sigma = K/tau, where tau is the interface thickness and K approximately equal 4 +/- 2 x 10(exp -6) dyne, enables prediction of our measured values of lambda* as well as results from prior experiments on miscible interfaces. These results indicate that even for miscible fluids, surface tension is generally a more significant factor than diffusion in interfacial stability and flow characteristics.

  15. Mechanics of finger-tip electronics

    NASA Astrophysics Data System (ADS)

    Su, Yewang; Li, Rui; Cheng, Huanyu; Ying, Ming; Bonifas, Andrew P.; Hwang, Keh-Chih; Rogers, John A.; Huang, Yonggang

    2013-10-01

    Tactile sensors and electrotactile stimulators can provide important links between humans and virtual environments, through the sensation of touch. Soft materials, such as low modulus silicones, are attractive as platforms and support matrices for arrays sensors and actuators that laminate directly onto the fingertips. Analytic models for the mechanics of three dimensional, form-fitting finger cuffs based on such designs are presented here, along with quantitative validation using the finite element method. The results indicate that the maximum strains in the silicone and the embedded devices are inversely proportional to the square root of radius of curvature of the cuff. These and other findings can be useful in formulating designs for these and related classes of body-worn, three dimensional devices.

  16. Viscous fingers in superheated geothermal systems

    SciTech Connect

    Fitzgerald, Shaun D.; Woods, Andres W.; Shook, Mike

    1994-01-20

    In this paper we investigate the physical controls upon the rate of vaporization of liquid as it is injected into a porous layer containing superheated vapour. We develop a simple model of the process and show that if liquid is injected at a relatively high rate, a small fraction of the liquid vaporizes and the porous layer becomes filled with hot liquid. In contrast, at low rates of injection a large fraction of the liquid may vaporize. We also describe a new and fundamental instability that can develop at a migrating liquid-vapour interface if the rate of injection is sufficiently small. This phenomenon is manifest in the form of liquid fingers growing from a liquid-vapour interface and is investigated through the use of analytical, experimental and numerical techniques.

  17. [Index finger pollicization for congenitally deficient first finger of the hand in children].

    PubMed

    Vázquez Rueda, F; Ayala Montoro, J; Blanco López, F; Ocaña Losa, J M

    2001-10-01

    Pollicization is a single-stage neurovascular pedicle transfer of the index digit to function as a thumb. The objective of this study is to investigate the results of index finger pollicization for correction of congenital deficiency of the first ray in pediatric hand. We have done 6 pollicizations of index fingers in 6 hands (there were 2 right hands, 2 left hands, and 1 bilaterally) in 5 patients (4 boys and 1 girl) who had absent or nonfunctioning thumbs (type III-V of Blauth's classification). Associated anomalies where numerous and included radial club hand, mirror hand and cardiovascular and urologic anomalies. The average time of Kirschner wire extraction was 32 days (30 to 36 days) and to beginning the hand rehabilitation at 5 degrees to 10 degrees day. The average age at pollicization was 5.5 years (range 2 to 8 years), and follow-up averaged 8 years (5 to 11 years). The cosmetic and functional results were excellent, with manual dexterity of prehension and opposition. Pollicization in children can be performed at least 2 years of age, to due of minor risk of neurovascular lesion but without delayed the cortical representation of the pollicized finger.

  18. Five- to 7-Year-Olds’ Finger Gnosia and Calculation Abilities

    PubMed Central

    Reeve, Robert; Humberstone, Judi

    2011-01-01

    The research examined the relationship between 65 5- to 7-year-olds’ finger gnosia, visuo-spatial working memory, and finger-use in solving single-digit addition problems. Their non-verbal IQ and basic reaction time were also assessed. Previous research has found significant changes in children’s representational abilities between 5 and 7 years. One aim of the research was to determine whether changes in finger representational abilities (finger gnosia) occur across these ages and whether they are associated with finger-use in computation. A second aim was to determine whether visuo-spatial working memory is associated with finger gnosia and computation abilities. We used latent class profile analysis to identify patterns of similarities and differences in finger gnosia and computation/finger-use abilities. The analysis yielded four finger gnosia subgroups that differed in finger representation ability. It also yielded four finger/computation subgroups that differed in the relationship between finger-use and computation success. Analysis revealed associations between computation finger-use/success subgroups, finger gnosia subgroups, and visuo-spatial working memory. A multinomial logistic regression analysis showed that finger gnosia subgroup membership and visuo-spatial working memory uniquely contribute to a model predicting finger-use in computation group membership. The results show that finger gnosia abilities change in the early school years, and that these changes are associated with the ability to use fingers to aid computation. PMID:22171220

  19. Real-time radiative divertor feedback control development for the NSTX-U tokamak using a vacuum ultraviolet spectrometer

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.; Kaita, R.; Stratton, B.

    2016-11-01

    A radiative divertor technique is planned for the NSTX-U tokamak to prevent excessive erosion and thermal damage of divertor plasma-facing components in H-mode plasma discharges with auxiliary heating up to 12 MW. In the radiative (partially detached) divertor, extrinsically seeded deuterium or impurity gases are used to increase plasma volumetric power and momentum losses. A real-time feedback control of the gas seeding rate is planned for discharges of up to 5 s duration. The outer divertor leg plasma electron temperature Te estimated spectroscopically in real time will be used as a control parameter. A vacuum ultraviolet spectrometer McPherson Model 251 with a fast charged-coupled device detector is developed for temperature monitoring between 5 and 30 eV, based on the Δn = 0, 1 line intensity ratios of carbon, nitrogen, or neon ion lines in the spectral range 300-1600 Å. A collisional-radiative model-based line intensity ratio will be used for relative calibration. A real-time Te-dependent signal within a characteristic divertor detachment equilibration time of ˜10-15 ms is expected.

  20. Large Area Divertor Temperature Measurements Using A High-speed Camera With Near-infrared FiIters in NSTX

    SciTech Connect

    Lyons, B C; Zweben, S J; Gray, T K; Hosea, J; Kaita, R; Kugel, H W; Maqueda, R J; McLean, A G; Roquemore, A L; Soukhanovskii, V A

    2011-04-05

    Fast cameras already installed on the National Spherical Torus Experiment (NSTX) have be equipped with near-infrared (NIR) filters in order to measure the surface temperature in the lower divertor region. Such a system provides a unique combination of high speed (> 50 kHz) and wide fi eld-of-view (> 50% of the divertor). Benchtop calibrations demonstrated the system's ability to measure thermal emission down to 330 oC. There is also, however, signi cant plasma light background in NSTX. Without improvements in background reduction, the current system is incapable of measuring signals below the background equivalent temperature (600 - 700 oC). Thermal signatures have been detected in cases of extreme divertor heating. It is observed that the divertor can reach temperatures around 800 oC when high harmonic fast wave (HHFW) heating is used. These temperature profiles were fi t using a simple heat diffusion code, providing a measurement of the heat flux to the divertor. Comparisons to other infrared thermography systems on NSTX are made.

  1. Tangential finger forces use mechanical advantage during static grasping.

    PubMed

    Slota, Gregory P; Latash, Mark L; Zatsiorsky, Vladimir M

    2012-02-01

    When grasping and manipulating objects, the central controller utilizes the mechanical advantage of the normal forces of the fingers for torque production. Whether the same is valid for tangential forces is unknown. The main purpose of this study was to determine the patterns of finger tangential forces and the use of mechanical advantage as a control mechanism when dealing with objects of nonuniform finger positioning. A complementary goal was to explore the interaction of mechanical advantage (moment arm) and the role a finger has as a torque agonist/antagonist with respect to external torques (±0.4 N m). Five 6-df force/torque transducers measured finger forces while subjects held a prism handle (6 cm width × 9 cm height) with and without a single finger displaced 2 cm (handle width). The effect of increasing the tangential moment arm was significant (p < .01) for increasing tangential forces (in >70% of trials) and hence creating greater moments. Thus, the data provides evidence that the grasping system as a rule utilizes mechanical advantage for generating tangential forces. The increase in tangential force was independent of whether the finger was acting as a torque agonist or antagonist, revealing their effects to be additive. PMID:22431218

  2. Comparison of Inter-Finger Connection Matrix Computation Techniques

    PubMed Central

    Martin, Joel R.; Terekhov, Alexander V.; Latash, Mark L.; Zatsiorsky, Vladimir M.

    2014-01-01

    A hypothesis was proposed that the central nervous system controls force production by the fingers through hypothetical neural commands (NCs). The NCs are scaled between values of 0 to 1, indicating no intentional force production or maximal voluntary contraction (MVC) force production, respectively. A matrix of finger inter-connections, [IFC], transforms NCs into finger forces. Two methods have been proposed to compute the [IFC]. The first method uses only single finger MVC trials and multiplies the [IFC] by a gain factor. The second method uses a neural network (NN) model based on experimental data. The performance of the two methods was compared on the MVC data and on a data set of sub-maximal forces, collected over a range of total forces and moments of force. The methods were compared in terms of: 1) ability to predict finger forces; 2) accuracy of NC reconstruction; and 3) preserved planarity of force data for sub-maximal force production task. Both methods did a reasonable job of predicting the total force in multi-finger MVC trials; however, the NN model performed better in regards to all other criteria. Overall, the results indicate that for modeling multi-finger interaction the NN method is preferable. PMID:23183029

  3. Finger release sequence for fastball and curveball pitches.

    PubMed

    Stevenson, J M

    1985-03-01

    The purpose of this study was to determine the action of the thumb, index, and middle fingers in releasing fastballs and curveballs for nine right-handed college pitchers. Micro-switches for the fingers were created by using two strips of electroconductive tape and a ball covered with electroconductive paint. Time data, accurate to 10(-4)s, were initiated by the stride foot onto a floor mat switch. When each digit left the ball, a corresponding timer was triggered with the final channel tripped by a contact switch in the catcher's glove. A total of 103 fastball and 88 curveball trials had complete data for each of the variables studied. Results showed that for the fastball, in 91.1% of the cases, the thumb preceded the middle and index fingers by approximately 6 ms. (p less than .001) but there was no significant difference between the middle and index fingers. The curveball data indicated that five of the nine pitchers had a definite release sequence of thumb first followed by middle then index finger (p less than .001). In total, 72.7% of the curveballs thrown had a release sequence of thumb, middle, and index fingers and 24.0% had a middle, thumb, index finger release sequence. The remaining 2.3% of the pitches had either similar times or odd combinations of release sequence.

  4. Tangential finger forces use mechanical advantage during static grasping.

    PubMed

    Slota, Gregory P; Latash, Mark L; Zatsiorsky, Vladimir M

    2012-02-01

    When grasping and manipulating objects, the central controller utilizes the mechanical advantage of the normal forces of the fingers for torque production. Whether the same is valid for tangential forces is unknown. The main purpose of this study was to determine the patterns of finger tangential forces and the use of mechanical advantage as a control mechanism when dealing with objects of nonuniform finger positioning. A complementary goal was to explore the interaction of mechanical advantage (moment arm) and the role a finger has as a torque agonist/antagonist with respect to external torques (±0.4 N m). Five 6-df force/torque transducers measured finger forces while subjects held a prism handle (6 cm width × 9 cm height) with and without a single finger displaced 2 cm (handle width). The effect of increasing the tangential moment arm was significant (p < .01) for increasing tangential forces (in >70% of trials) and hence creating greater moments. Thus, the data provides evidence that the grasping system as a rule utilizes mechanical advantage for generating tangential forces. The increase in tangential force was independent of whether the finger was acting as a torque agonist or antagonist, revealing their effects to be additive.

  5. Detection of Finger Height for a Multi-Touch Mouse

    NASA Astrophysics Data System (ADS)

    Fujieda, Ichiro; Okuda, Yuuto; Inoue, Yasunori; Nishino, Masayuki; Kosugi, Takashi

    2010-11-01

    An image of multiple fingers is acquired by an input system that consists of a camera with a fisheye lens, infrared LEDs, and a transparent shell. When the LEDs illuminate fingers uniformly, the distance between the fingertips and the lens can be deduced by analyzing the intensity of the fingertip regions and/or the size of the fingers in the image. Azimuth and polar angles of the fingertips are obtained from the image directly. Repeating this process provides a series of three-dimensional coordinates of multiple fingertips. Such information might be useful for realizing a multi-touch mouse with height detection capability.

  6. A hierarchical classification method for finger knuckle print recognition

    NASA Astrophysics Data System (ADS)

    Kong, Tao; Yang, Gongping; Yang, Lu

    2014-12-01

    Finger knuckle print has recently been seen as an effective biometric technique. In this paper, we propose a hierarchical classification method for finger knuckle print recognition, which is rooted in traditional score-level fusion methods. In the proposed method, we firstly take Gabor feature as the basic feature for finger knuckle print recognition and then a new decision rule is defined based on the predefined threshold. Finally, the minor feature speeded-up robust feature is conducted for these users, who cannot be recognized by the basic feature. Extensive experiments are performed to evaluate the proposed method, and experimental results show that it can achieve a promising performance.

  7. Narrow fingers in the Saffman-Taylor instability

    NASA Astrophysics Data System (ADS)

    Couder, Y.; Gerard, N.; Rabaud, M.

    1986-12-01

    Saffman-Taylor fingers with a relative width much smaller than the classical limit lambda = 0.5 are found when a small isolated bubble is located at their tip. These solutions are members of a family found by Saffman and Taylor (1958) neglecting superficial tension. Recent theories have shown that when capillary forces are taken into account an unphysical cusplike singularity would appear at the tip of all the fingers with lambda less than 0.5. Conversely, here the replacement of the tip by a small bubble makes these solutions possible. At large velocity these fingers show dendritic instability.

  8. Surface electromyogram for the control of anthropomorphic teleoperator fingers.

    PubMed

    Gupta, V; Reddy, N P

    1996-01-01

    Growing importance of telesurgery has led to the need for the development of synergistic control of anthropomorphic teleoperators. Synergistic systems can be developed using direct biological control. The purpose of this study was to develop techniques for direct biocontrol of anthropomorphic teleoperators using surface electromyogram (EMG). A computer model of a two finger teleoperator was developed and controlled using surface EMG from the flexor digitorum superficialis during flexion-extension of the index finger. The results of the study revealed a linear relationship between the RMS EMG and the flexion-extension of the finger model. Therefore, surface EMG can be used as a direct biocontrol for teleoperators and in VR applications.

  9. Finger rafting: a generic instability of floating elastic sheets.

    PubMed

    Vella, Dominic; Wettlaufer, J S

    2007-02-23

    Colliding ice floes are often observed to form a series of interlocking fingers. We show that this striking phenomenon is not a result of some peculiar property of ice but rather a general and robust mechanical phenomenon reproducible in the laboratory with other floating materials. We determine the theoretical relationship between the width of the resulting fingers and the material's mechanical properties and present experimental results along with field observations to support the theory. The generality of this "finger rafting" suggests that analogous processes may be responsible for creating the large-scale structures observed at the boundaries between Earth's convergent tectonic plates. PMID:17359135

  10. The social and economic consequences of finger amputations.

    PubMed

    Hovgaard, C; Angermann, P; Hovgaard, D

    1994-06-01

    120 patients with amputation of at least 1 of the 4 ulnar fingers were admitted to hospital. In none was replantation considered to be possible because of serious damage to the soft tissues and bone. 12 (3-18) years after the accident 80 percent of the patients assessed their condition as good or fair, even those with proximal amputation or loss of 2 or 3 fingers. Our observations do not support replantation when only one of the second-to-fifth fingers have been amputated.

  11. Dynamical degrees of freedom and correlations in isometric finger force production.

    PubMed

    James, Eric G

    2012-12-01

    Prior research has concluded that the correlations of isometric finger forces represent the extent to which the fingers are controlled as a single unit. If this is the case, finger force correlations should be consistent with estimates of the controlled (dynamical) degrees of freedom in finger forces. The present study examined the finger force correlations and the dynamical degrees of freedom in four isometric force tasks. The tasks were to produce a preferred level of force with the (a) Index, (b) Ring, (c) Both fingers and also to (d) Rest the fingers on the load cells. Dynamical degrees of freedom in finger forces were lowest in the Both finger force task and progressively higher in the Ring, Index and Resting finger force tasks. The finger force correlations were highest in the Resting and lowest in the Index and Ring finger tasks. The results for the dynamical degrees of freedom in finger forces were consistent with a reduction in degrees of freedom in response to the degrees of freedom problem and the task constraints. The results for the finger force correlations were inconsistent with a reduction in the dynamical degrees of freedom. These findings indicate that finger force correlations do not necessarily reflect the coupling of finger forces. The findings also highlight the value of time-domain analyses to reveal the organization of control in isometric finger forces.

  12. Experimental measurements and modeling of impurity transport in the divertor and boundary plasma of DIII-D

    SciTech Connect

    West, W.P.; Brooks, N.H.; Allen, S.L.

    1994-07-01

    Analysis of trace impurity injection experiments on DIII-D during a beam power scan is presented. Spectroscopic measu- rements indicate that as beam power is increased, and concomitantly ELM frequency and scrape-off-layer thickness increase while energy confinement decreases, the core impurity content decreases only slightly. Modeling of the edge plasma using the UEDGE 2D and NEWT1D plasma fluid codes indicate that as beam power is increased, the parallel forces on an impurity ion increase in the direction from the divertor and toward the core plasma. Experiments using the divertor cryopump to induce higher parallel particle flow toward the divertor demonstrate significant reduction in core impurity content. These results indicate that parallel forces on impurity ions in the scrape off layer are playing a significant role in core impurity content.

  13. Coherence imaging of scrape-off-layer and divertor impurity flows in the Mega Amp Spherical Tokamak (invited)

    SciTech Connect

    Silburn, S. A. Sharples, R. M.; Harrison, J. R.; Meyer, H.; Michael, C. A.; Howard, J.; Gibson, K. J.

    2014-11-15

    A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK’s Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obtained at frame rates up to 1 kHz, with flow resolution of around 1 km/s and spatial resolution better than 1 cm, over a 40° field of view. C III data have been tomographically inverted to obtain poloidal profiles of the parallel impurity flow in the divertor under various conditions. In this paper we present the details of the instrument design, operation, calibration, and data analysis as well as a selection of flow imaging results which demonstrate the diagnostic's capabilities.

  14. Coherence imaging of scrape-off-layer and divertor impurity flows in the Mega Amp Spherical Tokamak (invited).

    PubMed

    Silburn, S A; Harrison, J R; Howard, J; Gibson, K J; Meyer, H; Michael, C A; Sharples, R M

    2014-11-01

    A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK's Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obtained at frame rates up to 1 kHz, with flow resolution of around 1 km/s and spatial resolution better than 1 cm, over a 40° field of view. C III data have been tomographically inverted to obtain poloidal profiles of the parallel impurity flow in the divertor under various conditions. In this paper we present the details of the instrument design, operation, calibration, and data analysis as well as a selection of flow imaging results which demonstrate the diagnostic's capabilities.

  15. A physical model of an ejection suppressed CPS liquid lithium divertor target

    NASA Astrophysics Data System (ADS)

    Ou, Wei; Zheng, X. J.; Gou, F. J.; Deng, B. Q.; Peng, L. L.; Cao, X.; Zhang, W. W.; Xue, X. Y.

    2015-04-01

    A physical model has been developed which includes high temperature liquid lithium evaporation, the expanding motion of the liquid lithium vapour cloud, the shielding effects of the vapour cloud on incident plasma particle bombardments, ejection suppressed analysis and a perpendicular field proposal, and photon radiation, heat flux and transport in the lithium vapour cloud plasma. The engineering outline design scheme and the relevant parameters for the liquid lithium surface divertor target plate configured by discrete tiny capillary arrays have been established. Splashing can be suppressed by utilizing discrete and electrical insulating capillary porous systems (CPSs), since the conductivity among the capillary cells has been cut off by adopting a special kind of ceramic composite material made of a non-conducting and unbreakable composite which is able to withstand high temperatures. The formula to describe the temperature-dependent evaporation power has been derived. The maximum temperature increases of the discrete plasma-facing liquid lithium surface divertor target plate have been compared under the high energy flux deposition of 10 MJ m-2 during a 1 ms time duration with or without evaporation power. The results show that a high surface heat load can be withstood by the designed discrete plasma-facing liquid lithium surface divertor target plate due to violent evaporation. The energy deposition of incident energetic particles and weakly relativistic electrons from the scrape-off layer have been calculated. A laboratory experimental facility to simulate liquid lithium surface interactions with plasma has been set up. Research on lithium evaporation, re-deposition and ejection suppressed experiments under high density linear plasma dumping is ongoing.

  16. Tritium concentration measurements in the JET divertor by optical spectroscopy of a Penning discharge

    SciTech Connect

    Hillis, D.L.; Morgan, P.D.; Ehrenberg, J.K.; Groth, M.; Stamp, M.F.; Hellermann, M. von; Kumar, V.

    1998-06-01

    Obtaining precision measurements of the relative concentrations of hydrogen, deuterium, tritium, and helium in the divertor of a tokamak are an important task for nuclear fusion research. Control of the deuterium-tritium isotopic ratio while limiting the helium ash content in a fusion plasma are key factors for optimizing the fuel burn in a fusion reactor, like the International Tokamak Experimental Reactor (ITER). A diagnostic technique has been developed to measure the deuterium-tritium isotopic ratio in the divertor of the Joint European Torus (JET) with a species-selective Penning vacuum gauge. The Penning discharge provides a source of electrons to excite the neutral hydrogen isotopes in the pumping duct. Subsequently, the visible light from the hydrogen isotopes is collected in an optical fiber bundle, transferred away from the tokamak into a low radiation background area, and analyzed in a high resolution Czerny-Turner spectrometer, which is equipped with a fast charge coupled device (CCD) camera for optical detection. The intensity of the observed line emission (D{sub {alpha}} -- 6561.03 {angstrom}; and T{sub {alpha}} -- 6560.44 {angstrom}) is directly proportional to the partial pressure of each gas found in the divertor. The line intensity of each isotope is calibrated as a function of pressure. The ratio of the line intensities thus provides a direct measurement of the deuterium-tritium isotopic ratio. The lower limit for the determination of the deuterium-tritium isotopic ratio is about 0.5%. The applicable pressure range for this system is from 10{sup {minus}5} mbar to a few times 10{sup {minus}3} mbar.

  17. Far ultraviolet polychromator for spectroscopic characterization of the tokamak divertor and plasma scrape-off layer

    SciTech Connect

    Soukhanovskii, V.A.; Stutman, D.; May, M.J.; Finkenthal, M.; Moos, H.W.; Terry, J.L.; Goetz, J.A.; Lipschultz, B.

    1999-01-01

    The Plasma Spectroscopy Group of The Johns Hopkins University is developing diagnostics for spectroscopic characterization of the tokamak plasma scrape-off layer and divertor regions. A far ultraviolet polychromator has been designed for radiative divertor studies at the Alcator C-Mod and D-IIID tokamaks. Local measurements of resonant transitions of lithium- to boron-like ions of intrinsic or seeded low {ital Z} impurity elements will be performed along multiple chords around the {ital X} point. Planar diffraction gratings and stacked grids will be used for dispersion and angular collimation of radiation. Phosphor wavelength converters coupled to a photomultiplier tube by an optical fiber will be used as detectors. The design provides a wavelength resolution of {approx_equal}10 {Angstrom}, a spatial resolution of {le}2 cm, and an adequate photometric sensitivity. The in-vessel instrument, proposed for the Alcator C-Mod tokamak, will measure intensities of the lines at 1240 (N V), 765, 923 (N IV), and 990 {Angstrom} (N III). The port-mounted polychromator at DIII-D will be able to monitor intensities of 1550 (C IV), 977, 1176 (C III), and 1335 {Angstrom} (C II) lines. This, together with visible and bolometric diagnostics, should enable estimates of power losses, charge state distribution and local transport of the impurity ions in the divertor. A one-channel prototype of the C-Mod and D-IIID instruments is being built for the CDX-U spherical tokamak. Line-integrated brightnesses of the 2s{endash}2p transition at 1550 {Angstrom} will be measured and inverted to obtain C IV emissivity distribution. {copyright} {ital 1999 American Institute of Physics.}

  18. Production and fabrication of vanadium alloys for the radiative divertor program of DIII-D

    SciTech Connect

    Johnson, W.R.; Smith, J.P.; Stambaugh, R.D.

    1996-04-01

    V-4Cr-4-Ti alloy has been recently selected for use in the manufacture of a portion of the DIII-D Radiative Divertor modification, as part of an overall DIII-D vanadium alloy deployment effort developed by General Atomics (GA) in conjunction with the Argonne and Oak Ridge National Laboratories (ANL or ORNL). The goal of this work is to produce a production-scale heat of the alloy and fabricate it into product forms for the manufacture of a portion of the Radiative Divertor (RD) for the DIII-D tokamak, to develop the fabrications technology for manufacture of the vanadium alloy radiative Divertor components, and to determine the effects of typical tokamak environments in the behavior of the vanadium alloy. The production of a {approx}1300-kg heat of V-4Cr-4Ti alloy is currently in progress at Teledyne Wah Chang of Albany, oregon (TWCA) to provide sufficient material for applicable product forms. Two unalloyed vanadium ingots for the alloy have already been produced by electron beam melting of raw processes vanadium. Chemical compositions of one ingot and a portion of the second were acceptable, and Charpy V-Notch (CVN) impact test performed on processed ingot samples indicated ductile behavior. Material from these ingots are currently being blended with chromium and titanium additions, and will be vacuum-arc remelted into a V-4Cr-4Ti alloy ingot and converted into product forms suitable for components of the DIII-D RD structure. Several joining methods selected for specific applications in fabrication of the RD components are being investigated, and preliminary trials have been successful in the joining of V-alloy to itself by both resistance and inertial welding processes and to Inconel 625 by inertial welding.

  19. Analysis of a Multi-Machine Database on Divertor Heat Fluxes

    NASA Astrophysics Data System (ADS)

    Makowski, M. A.

    2011-10-01

    A coordinated effort to measure divertor heat flux characteristics in fully attached, similarly shaped H-mode plasmas on C-Mod, DIII-D and NSTX was carried out in 2010 in order to construct a predictive scaling relation applicable to next step devices including ITER, FNSF, and DEMO. Few published scaling laws are available and those that have been published were obtained under widely varying conditions and divertor geometries, leading to conflicting predictions for this critically important quantity. This study was designed to overcome these deficiencies. Corresponding plasma parameters were systematically varied in each tokamak, resulting in a combined data set in which Ip varies by a factor 3, Bt varies by a factor of 14.5, and major radius varies by a factor of 2.6. The derived scaling relation consistently predicts narrower heat flux widths than relations currently in use. Analysis of the combined data set reveals that the primary dependence of the parallel heat flux width is robustly inverse with Ip. All three tokamaks independently demonstrate this dependence. The midplane SOL profiles in DIII-D are also found to steepen with higher Ip, similar to the divertor heat flux profiles. Weaker dependencies on the toroidal field and normalized Greenwald density, fGW, are also found, but vary across devices and with the measure of the heat flux width used, either FWHM or integral width. In the combined data set, the strongest size scaling is with minor radius resulting in an approximately linear dependence on a /Ip . This suggests a scaling correlated with the inverse of the poloidal field, as would be expected for critical gradient or drift-based transport. Supported by the US DOE under DE-AC52-07NA27344 and DE-FC02-04ER54698.

  20. Impurity ion flow and temperature measured in a detached divertor with externally applied non-axisymmetric fields on DIII-D

    DOE PAGES

    Briesemeister, A. R.; Isler, R. C.; Allen, S. L.; Ahn, J. -W.; McLean, A. G.; Unterberg, E. A.; Hillis, D. L.; Fenstermacher, M. E.; Meyer, W. H.

    2014-11-15

    Externally applied non-axisymmetric magnetic fields are shown to have little effect on the impurity ion flow velocity and temperature as measured by the multichord divertor spectrometer in the DIII-D divertor for both attached and detached conditions. These experiments were performed in H-mode plasmas with the grad-B drift toward the target plates, with and without n = 3 resonant magnetic perturbations (RMPs). The flow velocity in the divertor is shown to change by as much as 30% when deuterium gas puffing is used to create detachment of the divertor plasma. No measurable changes in the C III flow were observed inmore » response to the RMP fields for the conditions used in this work. Images of the C III emission are used along with divertor Thomson scattering to show that the local electron and C III temperatures are equilibrated for the conditions shown.« less

  1. From frictional fingers to stick slip bubbles

    NASA Astrophysics Data System (ADS)

    Sandnes, Bjørnar; Jørgen Måløy, Knut; Flekkøy, Eirik; Eriksen, Jon

    2014-05-01

    Gas intrusion into wet porous/deformable/granular media occurs in a wide range of natural and engineered settings. Examples include hydrocarbon recovery, carbon dioxide geo-sequestration, gas venting in sediments and volcanic eruptions. In the case where the intruding gas is able to displace particles and grains, local changes in granular packing fraction govern the evolution of flow paths, resulting in complex pattern formation of the displacement flow. Here we investigate flow patterning as a compressed gas displaces a granular mixture confined in the narrow gap of a Hele-Shaw cell. We find a surprising variety of different pattern formation dynamics, and present a unified phase diagram of the flow morphologies we observe. This talk will focus on one particular transition the system undergoes: from frictional fingers to stick slip bubbles. We show that the frictional fluid flow patterns depend on granular mass loading and system elasticity, analogous to the behaviour of the well-known spring-block sliding friction problem.

  2. Examiner's finger-mounted fetal tissue oximetry

    NASA Astrophysics Data System (ADS)

    Kanayama, Naohiro; Niwayama, Masatsugu

    2014-06-01

    The best way to assess fetal condition is to observe the oxygen status of the fetus (as well as to assess the condition of infants, children, and adults). Previously, several fetal oximeters have been developed; however, no instrument has been utilized in clinical practice because of the low-capturing rate of the fetal oxygen saturation. To overcome the problem, we developed a doctor's finger-mounted fetal tissue oximeter, whose sensor volume is one hundredth of the conventional one. Additionally, we prepared transparent gloves. The calculation algorithm of the hemoglobin concentration was derived from the light propagation analysis based on the transport theory. We measured neonatal and fetal oxygen saturation (StO2) with the new tissue oximeter. Neonatal StO was measured at any position of the head regardless of amount of hair. Neonatal StO was found to be around 77%. Fetal StO was detected in every position of the fetal head during labor regardless of the presence of labor pain. Fetal StO without labor pain was around 70% in the first stage of labor and around 60% in the second stage of labor. We concluded that our new concept of fetal tissue oximetry would be useful for detecting fetal StO in any condition of the fetus.

  3. Development of Functional Recovery Training Device for Hemiplegic Fingers with Finger-expansion Facilitation Exercise by Stretch Reflex

    NASA Astrophysics Data System (ADS)

    Yu, Yong; Iwashita, Hisashi; Kawahira, Kazumi; Hayashi, Ryota

    This paper develops a functional recovery training device to perform repetition facilitating exercise for hemiplegic finger rehabilitation. On the facilitation exercise, automatic finger expansion can be realized and facilitated by stretch reflex, where a stimulation forces is applied instantaneously on flexion finger for making strech reflex and resistance forces are applied for maintaining the strech reflex. In this paper, novel parallel mechanisms, force sensing system with high sensitivity and resistance accompanying cooperation control method are proposed for sensing, controlling and realizing the stimulation force, resistance forces, strech reflex and repetition facilitating exercise. The effectivities and performances of the device are shown by some experiments.

  4. Hypohydration effect on finger skin temperature and blood flow during cold-water finger immersion.

    PubMed

    O'Brien, Catherine; Montain, Scott J

    2003-02-01

    This study was conducted to determine whether hypohydration (Hy) alters blood flow, skin temperature, or cold-induced vasodilation (CIVD) during peripheral cooling. Fourteen subjects sat in a thermoneutral environment (27 degrees C) during 15-min warm-water (42 degrees C) and 30-min cold-water (4 degrees C) finger immersion (FI) while euhydrated (Eu) and, again, during Hy. Hy (-4% body weight) was induced before FI by exercise-heat exposure (38 degrees C, 30% relative humidity) with no fluid replacement, whereas during Eu, fluid intake maintained body weight. Finger pad blood flow [as measured by laser-Doppler flux (LDF)] and nail bed (T(nb)), pad (T(pad)), and core (T(c)) temperatures were measured. LDF decreased similarly during Eu and Hy (32 +/- 10 and 33 +/- 13% of peak during warm-water immersion). Mean T(nb) and T(pad) were similar between Eu (7.1 +/- 1.0 and 11.5 +/- 1.6 degrees C) and Hy (7.4 +/- 1.3 and 12.6 +/- 2.1 degrees C). CIVD parameters (e.g., nadir, onset time, apex) were similar between trials, except T(pad) nadir was higher during Hy (10.4 +/- 3.8 degrees C) than during Eu (7.9 +/- 1.6 degrees C), which was attributed to higher T(c) in six subjects during Hy (37.5 +/- 0.2 degrees C), compared with during Eu (37.1 +/- 0.1 degrees C). The results of this study provide no evidence that Hy alters finger blood flow, skin temperature, or CIVD during peripheral cooling.

  5. Kinetic modeling of divertor heat load fluxes in the Alcator C-Mod and DIII-D tokamaks

    SciTech Connect

    Pankin, A. Y.; Rafiq, T.; Kritz, A. H.; Park, G. Y.; Chang, C. S.; Ku, S.; Brunner, D.; Hughes, J. W.; LaBombard, B.; Terry, J. L.; Groebner, R. J.

    2015-09-15

    The guiding-center kinetic neoclassical transport code, XGC0 [Chang et al., Phys. Plasmas 11, 2649 (2004)], is used to compute the heat fluxes and the heat-load width in the outer divertor plates of Alcator C-Mod and DIII-D tokamaks. The dependence of the width of heat-load fluxes on neoclassical effects, neutral collisions, and anomalous transport is investigated using the XGC0 code. The XGC0 code includes realistic X-point geometry, a neutral source model, the effects of collisions, and a diffusion model for anomalous transport. It is observed that the width of the XGC0 neoclassical heat-load is approximately inversely proportional to the total plasma current I{sub p.} The scaling of the width of the divertor heat-load with plasma current is examined for an Alcator C-Mod discharge and four DIII-D discharges. The scaling of the divertor heat-load width with plasma current is found to be weaker in the Alcator C-Mod discharge compared to scaling found in the DIII-D discharges. The effect of neutral collisions on the 1/I{sub p} scaling of heat-load width is shown not to be significant. Although inclusion of poloidally uniform anomalous transport results in a deviation from the 1/I{sub p} scaling, the inclusion of the anomalous transport that is driven by ballooning-type instabilities results in recovering the neoclassical 1/I{sub p} scaling. The Bohm or gyro-Bohm scalings of anomalous transport do not strongly affect the dependence of the heat-load width on plasma current. The inclusion of anomalous transport, in general, results in widening the width of neoclassical divertor heat-load and enhances the neoclassical heat-load fluxes on the divertor plates. Understanding heat transport in the tokamak scrape-off layer plasmas is important for strengthening the basis for predicting divertor conditions in ITER.

  6. Evidence for enhanced cross-field transport mechanisms in the TCV Snowflake divertor

    NASA Astrophysics Data System (ADS)

    Vijvers, Wouter

    2015-11-01

    TCV experiments demonstrate that cross-field plasma transport is enhanced in the Snowflake divertor (SFD) compared to a standard single-null divertor (SND). This enhanced cross-field transport spreads the exhaust power over a larger surface area than can be achieved by magnetic geometry alone and, thereby, reduces the peak heat flux. Comparison of the experiments with modelling identifies steepened radial gradients, ExB drift effects, and βp-driven instabilities as the responsible transport mechanisms. The uncovered physics is also relevant to the SND and may help improve predictive models for the target profiles in ITER and DEMO. In SFD variants with an X-point in the scrape-off layer (SOL), part of the heat flux profile is split off and redirected to an additional target. The resulting steepened radial gradients enhance cross-field diffusion. This is confirmed by EMC3-Eirene simulations, which show a factor two reduction of the parallel heat flux, even if diffusivities remain constant. Theoretical analysis predicts enhanced ExB drifts in the SFD by increased poloidal gradients of the temperature and density. The predictions are confirmed by target heat and particle flux measurements in dedicated experiments with both toroidal field directions. Cross-field convection by curvature-driven modes at high βp (``churning modes'') explains the large fluxes into the private flux region of the SFD. This activates the extra targets and reduces the peak power to the primary targets up to a factor four. This mechanism is expected to be most effective when the divertor conditions are most severe: near the separatrix of a narrow, high-pressure SOL of a large tokamak. These and other alternative divertor configurations thus provide potential solutions to the power exhaust challenge, as well as laboratories to study SOL transport, one of the most important topics in tokamak research. This project was carried out with financial support from NWO. The work was carried out within

  7. Magnetic-divertor stabilization of an axisymmetric plasma with anisotropic temperature

    SciTech Connect

    Sasagawa, Y.; Katanuma, I.; Mizoguchi, Y.; Cho, T.; Pastukhov, V. P.

    2006-12-15

    Magnetohydrodynamic stabilization of an axisymmetric mirror plasma with a magnetic divertor is studied. An equation is found for the flute modes, which includes the stabilizing influence of ion temperature anisotropy and nonparaxial magnetic fields, as well as a finite ion Larmor radius. It is shown that if the density profile is sufficiently gentle, then the nonparaxial configuration can stabilize all modes as long as ion temperature is radially uniform. This can be demonstrated even when the density vanishes on the separatrix and even for small ion Larmor radii. It is found, however, that the ion temperature gradient makes the unstable region wider; high ion temperature is required to stabilize the flute mode.

  8. One-dimensional transport code modelling of the limiter-divertor region in tokamaks

    SciTech Connect

    Ogden, J.M.; Post, D.E.; Jensen, R.V.; Seidl, F.G.P.

    1980-02-01

    A model of the limiter-divertor scrape-off region has been incorporated into the BALDUR one-dimensional tokamak transport code. Simulations of PDX and ALCATOR have been carried out for ohmic and neutral beam heated cases. In particular, we have studied how the edge conditions and energy loss mechanisms of PDX depend upon plasma density, and compared our results with analytic estimates. The sensitivity of the results to changes in the transport coefficients and scrape-off model is also discussed.

  9. Design and calibration of the fast ion diagnostic experiment detector on the poloidal divertor experiment

    SciTech Connect

    Kaita, R.; Goldston, R.J.; Meyerhofer, D.; Eridon, J.

    1981-12-01

    A special purpose charge-exchange analyzer was constructed to measure the spatial distribution of hot-plasma ions, as a function of energy and time, in the poloidal divertor experiment (PDX). The fast neutrals produced by charge exchange within the tokamak are reionized as they pass through a helium stripping cell in the detector. The energies of these ions are determined by the trajectories they follow between cylindrical deflection plates which are set at known electrostatic potentials. We describe the technique used to calibrate the response of this system as it depends on the energies and the masses of the particles which are being detected.

  10. Fast time resolution charge-exchange measurements during the fishbone instability in the poloidal divertor experiment

    SciTech Connect

    Beiersdorfer, P.; Kaita, R.; Goldston, R.J.

    1984-01-01

    Measurements of fast ion losses due to the fishbone instability during high ..beta../sub T/q neutral beam heated discharges in the Poloidal Divertor Experiment have been made using two new vertical-viewing charge-exchange analyzers. The measurements show that the instability has an n=1 toroidal mode number, and that it ejects beam ions in a toroidally rotating beacon directed outward along a major radius. Observations of ejected ions with energies up to twice the beam injection energy at R approx. = R/sub 0/ + a indicate the presence of a non-..mu..-conserving acceleration mechanism.

  11. Finger vein recognition based on local directional code.

    PubMed

    Meng, Xianjing; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2012-01-01

    Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP. PMID:23202194

  12. L'index significant (The Pointed Index Finger).

    ERIC Educational Resources Information Center

    Calbris, G.

    1979-01-01

    In the framework of a study of nonverbal communication, the various meanings attached to the pointed index finger are analyzed. The question is raised as to what extent the findings hold for cultures other than French. (AMH)

  13. Suppression of viscous fingering in nonflat Hele-Shaw cells

    NASA Astrophysics Data System (ADS)

    Brandão, Rodolfo; Fontana, João V.; Miranda, José A.

    2014-11-01

    Viscous fingering formation in flat Hele-Shaw cells is a classical and widely studied fluid mechanical problem. Recently, instead of focusing on the development of the fingering instability, researchers have devised different strategies aiming to suppress its appearance. In this work, we study a protocol that intends to inhibit the occurrence of fingering instabilities in nonflat (spherical and conical) Hele-Shaw cell geometries. By using a mode-coupling theory to describe interfacial evolution, plus a variational controlling technique, we show that viscous fingering phenomena can be minimized in such a confined, curved environment by properly manipulating a time-dependent injection flow rate Q (t ) . Explicit expressions for Q (t ) are derived for the specific cases of spherical and conical cells. The suitability of the controlling method is verified for linear and weakly nonlinear stages of the flow.

  14. [Spontaneous Non Ischaemic Blue Finger: A Rare and Benign Phenomenon].

    PubMed

    Franco, Daniela; Alves, Daniela; Almeida, Ana Cristina; Almeida, Carlos Costa; Moreno, Cecília; Freixo, Joâo

    2015-01-01

    The spontaneous non-ischaemic blue finger is a rare and benign disorder, characterized by purple discoloration of a finger, with complete resolution. This article reports the case of a woman of 88 years, which after a few hours of stay in the emergency department developed without associated trauma, a purplish color of the 3rd finger of the right hand, with a palpable pulse and without temperature changes or pain. The etiological investigation was negative. The patient was assessed one week after the event and showed completeresolution. There are several diseases that share the same signs and symptoms, as such the diagnosis is based on the spontaneous violaceous color sparing the finger tip, and fast resolution without treatment. Though being a harmless phenomenon, it requires early assessment for timely differential diagnosis with severe pathologies.

  15. Seal finger: A case report and review of the literature

    PubMed Central

    White, Colin P; Jewer, David D

    2009-01-01

    A recent case of seal finger which was misdiagnosed and hence mistreated at the patient’s first presentation is described. The patient was eventually referred to a hand specialist and after the correct treatment with tetracycline, responded well without any long-term sequelae. Seal finger is an occupational injury that occurs to those who work directly or indirectly with seals. The disease entity has been described in both Scandinavian and Canadian literature. The causative microorganism was unknown until 1991, when Mycoplasma phocacerebrale was isolated from both the finger of a patient with seal finger and from the mouth of a seal that bit the patient. Although rare, the disease is not uncommon in marine workers, biologists and veterinarians. Prompt identification based on patient history and treatment with oral tetracycline is pendant to a favourable patient outcome. PMID:21119845

  16. Classification of finger vibrotactile input using scalp EEG.

    PubMed

    He, Yongtian; Contreras-Vidal, Jose L

    2015-01-01

    While there are many output brain-computer interface (output BCIs) studies, few have examined the input pathway, namely decoding the sensory input. To examine the possibility of building a BCI with sensory input using scalp electroencephalography (EEG), this study builds a classifier based on Local Fisher Discriminant Analysis (LFDA) and Gaussian Mixture Model (GMM) to classify neural activity generated by vibrotactile sensory stimuli delivered to the fingers. Small vibrators were placed on the fingertips of the participant. They vibrated one by one in a random sequence while the participant sat still with eyes closed. EEG data were recorded and later used to classify which finger was vibrated. There were two tasks: one focusing on differentiating between ipsilateral fingers, the other one focusing on differentiating contralateral fingers. Decoding accuracies were high in both tasks: 97.6% and 99.3% respectively. Event-related EEG features in both amplitude and power domain are discussed. PMID:26737347

  17. [Raynaud's phenomenon and other circulatory disorders of the fingers].

    PubMed

    Mahler, Felix

    2014-02-26

    Raynaud's phenomenon (RP) is defined as attacks of blanking, subsequent cyanosis and rubeosis of fingers due to vasospasms in response to cold or emotional stimuli. Primary RP has no known underlying cause and occurs mainly in young and otherwise healthy women. Secondary RP goes along with various causes such as connective tissue diseases, toxic substances, drugs, physical trauma or organic finger artery occlusions, and occurs at any age and in both genders. Related affections are acrocyanosis and finger artery occlusions either due to arteriosclerosis or vasculitis. Also spontaneous finger hematoma may provoke an episode of RP. Therapeutically strict cold protection and avoidance of possible noxa is recommended besides the treatment of underlying diseases. No standard vasoactive drug has proven ideal for RP due to side effects. In cases with rest pain or ulcerations the same principles are applied as in ischemic diseases with no possibility for revascularization.

  18. Tension Distribution in a Tendon-Driven Robotic Finger

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor)

    2013-01-01

    A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

  19. Finger Growth in Surfactant Solution in Hele-Shaw Cells

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takehiro; Yamashita, Atsushi; Nakamura, Yousuke; Hashimoto, Takamasa; Mori, Noriyasu

    2006-05-01

    Viscous fingering in surfactant solutions was experimentally studied. Aqueous solutions of cetyltrimethylammonium bromide (CTAB) with sodium salicylate (NaSal) as a counter ion were used as test fluids. Excess of counter ion was added into a surfactant solution of CTAB to configure network structures of wormlike micelles. The experiments were mainly carried out using a square Hele-Shaw cell. The structure of fingering pattern was dimensionally analyzed to classify the patterns into three types. In addition, growth phenomena distinguishing for the viscous finger in the CTAB/NaSal solutions were observed: surface instabilities with dendrites, and a sudden protrusion from a cuspidate shaped finger tip. The dependence of the sudden protrusion on the shear rate was confirmed by the experiment using a rectangular cell.

  20. Classification of finger vibrotactile input using scalp EEG.

    PubMed

    He, Yongtian; Contreras-Vidal, Jose L

    2015-01-01

    While there are many output brain-computer interface (output BCIs) studies, few have examined the input pathway, namely decoding the sensory input. To examine the possibility of building a BCI with sensory input using scalp electroencephalography (EEG), this study builds a classifier based on Local Fisher Discriminant Analysis (LFDA) and Gaussian Mixture Model (GMM) to classify neural activity generated by vibrotactile sensory stimuli delivered to the fingers. Small vibrators were placed on the fingertips of the participant. They vibrated one by one in a random sequence while the participant sat still with eyes closed. EEG data were recorded and later used to classify which finger was vibrated. There were two tasks: one focusing on differentiating between ipsilateral fingers, the other one focusing on differentiating contralateral fingers. Decoding accuracies were high in both tasks: 97.6% and 99.3% respectively. Event-related EEG features in both amplitude and power domain are discussed.

  1. Fingered bola body, bola with same, and methods of use

    NASA Technical Reports Server (NTRS)

    Dzenitis, John M. (Inventor); Billica, Linda W. (Inventor)

    1994-01-01

    The present invention discloses bola bodies, bolas, and a snaring method which makes use such devices. A bola body, according to the present invention, is nonspherical or irregular in shape rather than a smooth sphere or ovoid body. One or more fingers extends from the bola body. These fingers may be relatively straight or they may have crooked or bent portions to enhance entanglement with a bola line or lines or with each other. Two or more of such fingers may be used and may be regularly or irregularly spaced apart on a bola body. A bola with such bodies includes lines which are connected to the other bodies. In one particular embodiment of a bola body, according to the present invention, the body has an irregular shape with a bottom rectangular portion and a top pyramid portion forming a nose. A plurality of fingers is extended from the pyramidal top portion with one finger extended up and away from each of four corners of the top portion. Such a bola body tends to be initially oriented with its nose and fingers against an object being snared since the body is pulled nose first when a bola line is secured at the tip of the pyramidal portion of the bola body. With such a bola, an unwrapping bola body can slip around a target member so that two of the rod-shaped fingers catch a bola line and guide it into an area or crook between the fingers and a side of the top pyramidal portion of the bola body. Tension on the bola line maintains the line in the crook and tends to press the fingers against the unwrapped target member to stabilize the wrapping of the line about the target member. With such a bola, it is difficult for two or more lines unwrapping in different directions to move past one another without being forced together by line tension. Also, the fingers of such bola bodies may hook and hold each other. The fingers may also hook or entangle some object on or portion of the target member. A probable known target member has known dimensions and shapes so that

  2. Laboratory experiments on the structure of salt fingers

    NASA Astrophysics Data System (ADS)

    Taylor, John; Bucens, Paul

    1989-11-01

    We investigated the structure of salt fingers in a laboratory tank using horizontal and vertical conductivity and temperature profiles; similar measurements have been made of salt finger microstructure in the ocean. Visualization of the salt fingers using fluorescent dye mixed into the upper layer showed that they were disordered, with new fingers being formed at the edge of the gradient region then growing into the gradient. Because of the disordered state of the fingers the average coherence between the signals for two vertically separated sensors was small, even though the separation of the sensors was of the order of the finger width. The peak in horizontal gradient spectrum was close to both the wavenumber of salt fingers with the maximum growth rate and to the wavenumber of fingers that maximize the buoyancy flux in HOWARD and VERONIS' (1987, Journal of Fluid Mechanics, 183, 1-23), salt finger model. Assuming that the vertical advection of the mean temperature gradient within an individual finger was balanced by horizontal heat diffusion, we derived an estimate for the buoyancy flux due to heat from the variance of the horizontal temperature gradient. On average, this estimate for the flux was 0.6 that determined from the rate of change of the mean layer properties, and our result supports the use of this technique for estimating salt finger fluxes in the ocean. We also derived the buoyancy flux ratio, defined as the ratio of the buoyancy flux due to heat to that due to salt, from the ratio of the variances of the horizontal temperature and salinity profiles. Our estimate for the flux ratio from horizontal profiles was in agreement with that derived from the vertical profiles. At comparable stability ratios the salt flux and buoyancy flux ratio determined from the present experiments were closer to those presented by TURNER (1967, Deep-Sea Research, 14, 599-611) and SCHMITT (1979a, Journal of Marine Research, 37, 419-436) than to the later results of

  3. High-pressure injection injury of the finger

    PubMed Central

    Saraf, Sanjay

    2012-01-01

    The high-pressure injection injuries are unusual injuries and the extent of tissue damage is often under estimated. They represent potentially disabling forms of trauma and have disastrous effects on tissues if not treated promptly. We present a case of high pressure injection injury to the finger from lubricant oil. The patient presented late with necrosis of volar tissue of left index finger. The patient was aggressively managed in stages, with delayed flap cover, with satisfactory functional and aesthetic outcome. PMID:23325982

  4. Finger blood content, light transmission, and pulse oximetry errors.

    PubMed

    Craft, T M; Lawson, R A; Young, J D

    1992-01-01

    The changes in light emitting diode current necessary to maintain a constant level of light incident upon a photodetector were measured in 20 volunteers at the two wavelengths employed by pulse oximeters. Three states of finger blood content were assessed; exsanguinated, hyperaemic, and normal. The changes in light emitting diode current with changes in finger blood content were small and are not thought to represent a significant source of error in saturation as measured by pulse oximetry.

  5. Integrating optical finger motion tracking with surface touch events

    PubMed Central

    MacRitchie, Jennifer; McPherson, Andrew P.

    2015-01-01

    This paper presents a method of integrating two contrasting sensor systems for studying human interaction with a mechanical system, using piano performance as the case study. Piano technique requires both precise small-scale motion of fingers on the key surfaces and planned large-scale movement of the hands and arms. Where studies of performance often focus on one of these scales in isolation, this paper investigates the relationship between them. Two sensor systems were installed on an acoustic grand piano: a monocular high-speed camera tracking the position of painted markers on the hands, and capacitive touch sensors attach to the key surfaces which measure the location of finger-key contacts. This paper highlights a method of fusing the data from these systems, including temporal and spatial alignment, segmentation into notes and automatic fingering annotation. Three case studies demonstrate the utility of the multi-sensor data: analysis of finger flexion or extension based on touch and camera marker location, timing analysis of finger-key contact preceding and following key presses, and characterization of individual finger movements in the transitions between successive key presses. Piano performance is the focus of this paper, but the sensor method could equally apply to other fine motor control scenarios, with applications to human-computer interaction. PMID:26082732

  6. Detecting overblown flute fingerings from the residual noise spectrum.

    PubMed

    Verfaille, Vincent; Depalle, Philippe; Wanderley, Marcelo M

    2010-01-01

    Producing a tone by increasing the blowing pressure to excite a higher frequency impedance minimum, or overblowing, is widely used in standard flute technique. In this paper, the effect of overblowing a fingering is explored with spectral analysis, and a fingering detector is designed based on acoustical knowledge and pattern classification techniques. The detector performs signal analysis of the strong broadband signal, that is, spectrally shaped by the pipe impedance, and measures the spectral energy during the attack around multiples of the fundamental frequency sub-multiples over the first octave and a half. It is trained and evaluated on sounds recorded with four expert performers. They played six series of tones from overblown and regular fingerings, with frequencies that are octave- and non-octave-related to the playing frequency. The best of the four proposed sound descriptors allows for a detection error below 1.3% for notes with two and three fingerings (C(5), D(5), C(6), and Cmusical sharp(6)) and below 14% for four (E(6)) or five fingerings (G(6)). The error is shown to dramatically increase when two fingerings' impedance become too similar (E(6) and A(4) and G(6) and C(5)). PMID:20058998

  7. Fluidic Channels Produced by Electro Hydrodynamic Viscous Fingering

    NASA Astrophysics Data System (ADS)

    Behler, Kristopher; Wetzel, Eric

    2010-03-01

    Viscous fingering is a term describing fingerlike extensions of liquid from a column of low viscosity liquid that has been injected into a more viscous liquid. The modification of viscous fingering, known as electro hydrodynamic viscous fingering (EHVF), utilizes large electrical potentials of 10-60 kV. The fingers see a reduction in size and increase in branching behavior due to the potential applied to the system. The resulting finely structured patterns are analogous to biological systems such as blood vessels and the lymphatic system. In this study silicone oils and water were studied in thin channel Hele-Shaw cells. The interfacial tension was optimized by altering the surfactant concentration in the silicone oils. EHVF of liquid filled packed beds consisting of beads and silicone oils showed retardation of the relaxation of the fingers after the voltage was turned off. Decreased relaxation provides a means to solidify patterns into a curable material, such as polydimethylsiloxane (PDMS). After the water is evacuated from the fingers, the cured materials then possess hollow channels that can be refilled and emptied, thus creating an artificial circulatory system.

  8. Biomechanical Analysis of Force Distribution in Human Finger Extensor Mechanisms

    PubMed Central

    Hu, Dan; Ren, Lei; Howard, David; Zong, Changfu

    2014-01-01

    The complexities of the function and structure of human fingers have long been recognised. The in vivo forces in the human finger tendon network during different activities are critical information for clinical diagnosis, surgical treatment, prosthetic finger design, and biomimetic hand development. In this study, we propose a novel method for in vivo force estimation for the finger tendon network by combining a three-dimensional motion analysis technique and a novel biomechanical tendon network model. The extensor mechanism of a human index finger is represented by an interconnected tendinous network moving around the phalanx's dorsum. A novel analytical approach based on the “Principle of Minimum Total Potential Energy” is used to calculate the forces and deformations throughout the tendon network of the extensor mechanism when subjected to an external load and with the finger posture defined by measurement data. The predicted deformations and forces in the tendon network are in broad agreement with the results obtained by previous experimental in vitro studies. The proposed methodology provides a promising tool for investigating the biomechanical function of complex interconnected tendon networks in vivo. PMID:25126576

  9. Modeling NAPL dissolution fingering with upscaled mass transfer rate coefficients

    NASA Astrophysics Data System (ADS)

    Imhoff, Paul T.; Farthing, Matthew W.; Miller, Cass T.

    2003-10-01

    The dissolution of nonaqueous phase liquids (NAPLs) at residual saturation in porous media has sometimes resulted in the development of preferential dissolution pathways or NAPL dissolution fingers. While NAPL dissolution fingering may be modeled using numerical simulators with fine discretization, this approach is computational intensive. We derived an expression for an upscaled mass transfer rate coefficient that accounts for the growth of dissolution fingers within porous media contaminated uniformly with residual NAPL. This expression was closely related to the lengthening of the dissolution front. Data from physical experiments and numerical simulations in two dimensions were used to examine the growth of the dissolution front and the corresponding upscaled mass transfer rate coefficient. Using this upscaled mass transfer rate coefficient, the time when dissolution fingering results in a reduction in the overall mass transfer rate and thus controls the rate of NAPL dissolution was determined. This crossover time is a convenient parameter for assessing the influence of dissolution fingering on NAPL removal. For the physical experiments and numerical simulations analyzed in this study, the crossover time to dissolution fingering control always occurred before the dissolution front had moved 14 cm within NAPL-contaminated porous media, which is small compared to the scale of typical systems of concern. To verify the utility of this approach, data from a three-dimensional physical experiment were predicted reasonably well using an upscaled mass transfer rate coefficient that was determined independently from this experiment.

  10. Integrating optical finger motion tracking with surface touch events.

    PubMed

    MacRitchie, Jennifer; McPherson, Andrew P

    2015-01-01

    This paper presents a method of integrating two contrasting sensor systems for studying human interaction with a mechanical system, using piano performance as the case study. Piano technique requires both precise small-scale motion of fingers on the key surfaces and planned large-scale movement of the hands and arms. Where studies of performance often focus on one of these scales in isolation, this paper investigates the relationship between them. Two sensor systems were installed on an acoustic grand piano: a monocular high-speed camera tracking the position of painted markers on the hands, and capacitive touch sensors attach to the key surfaces which measure the location of finger-key contacts. This paper highlights a method of fusing the data from these systems, including temporal and spatial alignment, segmentation into notes and automatic fingering annotation. Three case studies demonstrate the utility of the multi-sensor data: analysis of finger flexion or extension based on touch and camera marker location, timing analysis of finger-key contact preceding and following key presses, and characterization of individual finger movements in the transitions between successive key presses. Piano performance is the focus of this paper, but the sensor method could equally apply to other fine motor control scenarios, with applications to human-computer interaction.

  11. Biomechanical analysis of force distribution in human finger extensor mechanisms.

    PubMed

    Hu, Dan; Ren, Lei; Howard, David; Zong, Changfu

    2014-01-01

    The complexities of the function and structure of human fingers have long been recognised. The in vivo forces in the human finger tendon network during different activities are critical information for clinical diagnosis, surgical treatment, prosthetic finger design, and biomimetic hand development. In this study, we propose a novel method for in vivo force estimation for the finger tendon network by combining a three-dimensional motion analysis technique and a novel biomechanical tendon network model. The extensor mechanism of a human index finger is represented by an interconnected tendinous network moving around the phalanx's dorsum. A novel analytical approach based on the "Principle of Minimum Total Potential Energy" is used to calculate the forces and deformations throughout the tendon network of the extensor mechanism when subjected to an external load and with the finger posture defined by measurement data. The predicted deformations and forces in the tendon network are in broad agreement with the results obtained by previous experimental in vitro studies. The proposed methodology provides a promising tool for investigating the biomechanical function of complex interconnected tendon networks in vivo. PMID:25126576

  12. Enhancement of finger motion range with compliant anthropomorphic joint design.

    PubMed

    Çulha, Utku; Iida, Fumiya

    2016-04-01

    Robotic researchers have been greatly inspired by the human hand in the search to design and build adaptive robotic hands. Especially, joints have received a lot of attention upon their role in maintaining the passive compliance that gives the fingers flexibility and extendible motion ranges. Passive compliance, which is the tendency to be employed in motion under the influence of an external force, is the result of the stiffness and the geometrical constraints of the joints that define the direction of the motion. Based on its building elements, human finger joints have multi-directional passive compliance which means that they can move in multiple axis of motion under external force. However, due to their complex anatomy, only simplified biomechanical designs based on physiological analysis are preferred in present day robotics. To imitate the human joints, these designs either use fixed degree of freedom mechanisms which substantially limit the motion axes of compliance, or soft materials that can deform in many directions but hinder the fingers' force exertion capacities. In order to find a solution that lies between these two design approaches, we are using anatomically correct finger bones, elastic ligaments and antagonistic tendons to build anthropomorphic joints with multi-directional passive compliance and strong force exertion capabilities. We use interactions between an index finger and a thumb to show that our joints allow the extension of the range of motion of the fingers up to 245% and gripping size to 63% which can be beneficial for mechanical adaptation in gripping larger objects. PMID:26891473

  13. Detecting overblown flute fingerings from the residual noise spectrum.

    PubMed

    Verfaille, Vincent; Depalle, Philippe; Wanderley, Marcelo M

    2010-01-01

    Producing a tone by increasing the blowing pressure to excite a higher frequency impedance minimum, or overblowing, is widely used in standard flute technique. In this paper, the effect of overblowing a fingering is explored with spectral analysis, and a fingering detector is designed based on acoustical knowledge and pattern classification techniques. The detector performs signal analysis of the strong broadband signal, that is, spectrally shaped by the pipe impedance, and measures the spectral energy during the attack around multiples of the fundamental frequency sub-multiples over the first octave and a half. It is trained and evaluated on sounds recorded with four expert performers. They played six series of tones from overblown and regular fingerings, with frequencies that are octave- and non-octave-related to the playing frequency. The best of the four proposed sound descriptors allows for a detection error below 1.3% for notes with two and three fingerings (C(5), D(5), C(6), and Cmusical sharp(6)) and below 14% for four (E(6)) or five fingerings (G(6)). The error is shown to dramatically increase when two fingerings' impedance become too similar (E(6) and A(4) and G(6) and C(5)).

  14. Integrating optical finger motion tracking with surface touch events.

    PubMed

    MacRitchie, Jennifer; McPherson, Andrew P

    2015-01-01

    This paper presents a method of integrating two contrasting sensor systems for studying human interaction with a mechanical system, using piano performance as the case study. Piano technique requires both precise small-scale motion of fingers on the key surfaces and planned large-scale movement of the hands and arms. Where studies of performance often focus on one of these scales in isolation, this paper investigates the relationship between them. Two sensor systems were installed on an acoustic grand piano: a monocular high-speed camera tracking the position of painted markers on the hands, and capacitive touch sensors attach to the key surfaces which measure the location of finger-key contacts. This paper highlights a method of fusing the data from these systems, including temporal and spatial alignment, segmentation into notes and automatic fingering annotation. Three case studies demonstrate the utility of the multi-sensor data: analysis of finger flexion or extension based on touch and camera marker location, timing analysis of finger-key contact preceding and following key presses, and characterization of individual finger movements in the transitions between successive key presses. Piano performance is the focus of this paper, but the sensor method could equally apply to other fine motor control scenarios, with applications to human-computer interaction. PMID:26082732

  15. Biomechanical analysis of force distribution in human finger extensor mechanisms.

    PubMed

    Hu, Dan; Ren, Lei; Howard, David; Zong, Changfu

    2014-01-01

    The complexities of the function and structure of human fingers have long been recognised. The in vivo forces in the human finger tendon network during different activities are critical information for clinical diagnosis, surgical treatment, prosthetic finger design, and biomimetic hand development. In this study, we propose a novel method for in vivo force estimation for the finger tendon network by combining a three-dimensional motion analysis technique and a novel biomechanical tendon network model. The extensor mechanism of a human index finger is represented by an interconnected tendinous network moving around the phalanx's dorsum. A novel analytical approach based on the "Principle of Minimum Total Potential Energy" is used to calculate the forces and deformations throughout the tendon network of the extensor mechanism when subjected to an external load and with the finger posture defined by measurement data. The predicted deformations and forces in the tendon network are in broad agreement with the results obtained by previous experimental in vitro studies. The proposed methodology provides a promising tool for investigating the biomechanical function of complex interconnected tendon networks in vivo.

  16. Fingering Convection and its Consequences for Accreting White Dwarfs

    NASA Astrophysics Data System (ADS)

    Vauclair, Sylvie; Vauclair, Gérard; Deal, Morgan; Wachlin, F. C.

    2015-06-01

    A number of white dwarf stars show absoption lines of heavy elements in their spectra. Many of them also exhibit infra-red excess in their spectral energy distribution. These observations prove that these white dwarfs are surrounded by an orbiting debris disk resulting from the disruption of rocky planetesimals, remnants of the primordial planetary system. Part of the material from the debris disk is accreted onto the white dwarfs, explaining the presence of heavy elements in their outer layers. Previous attempts to estimate the accretion rates have overlooked the importance of the fingering convection. The fingering convection is an instability triggered by the accumulation in the white dwarf outer layers of material heavier than the underlying H-rich (for the DA) or the He-rich (for the DB) composition. The fingering convection induces a deep mixing of the accreted material. Our preliminary simulations of the fingering convection show that the effect may be important in DA white dwarfs. The accretion rates needed in order to reproduce the observed heavy element abundances exceed by order of magnitudes the accretion rates estimated when this extra-mixing is ignored. By contrast, in the cases of the DB white dwarfs that we have considered in our simulations the fingering convection either does not occur or has very little effects on the derived accretion rates. We have undertaken a systematic exploration of the consequences of the fingering convection in accreting white dwarfs.

  17. Viscous Fingering Induced Flow Instability in Multidimensional Liquid Chromatography

    SciTech Connect

    Mayfield, Kirsty; Shalliker, R. Andrew; Catchpoole, Heather J.; Sweeney, Alan P.; Wong, Victor; Guiochon, Georges A

    2005-07-01

    Viscous fingering is a flow instability phenomenon that results in the destabilisation of the interface between two fluids of differing viscosities. The destabilised interface results in a complex mixing of the two fluids in a pattern that resembles fingers. The conditions that enhance this type of flow instability can be found in coupled chromatographic separation systems, even when the solvents used in each of the separation stages have seemingly similar chemical and physical properties (other than viscosity). For example, the viscosities of acetonitrile and methanol are sufficiently different that instability at the interface between these two solvents can be established and viscous fingering results. In coupled chromatographic systems, the volume of solvent transported from one separation dimension to the second often exceeds the injection volume by two or more orders of magnitude. As a consequence, viscous fingering may occur, when otherwise following the injection of normal analytical size injection plugs viscous fingering would not occur. The findings in this study illustrate the onset of viscous fingering in emulated coupled chromatographic systems and show the importance of correct solvent selection for optimum separation performance.

  18. 15-zinc finger protein Bloody Fingers is required for zebrafish morphogenetic movements during neurulation.

    PubMed

    Sumanas, Saulius; Zhang, Bo; Dai, Rujuan; Lin, Shuo

    2005-07-01

    A novel zebrafish gene bloody fingers (blf) encoding a 478 amino acid protein containing fifteen C(2)H(2) type zinc fingers was identified by expression screening. As determined by in situ hybridization, blf RNA displays strong ubiquitous early zygotic expression, while during late gastrulation and early somitogenesis, blf expression becomes transiently restricted to the posterior dorsal and lateral mesoderm. During later somitogenesis, blf expression appears only in hematopoietic cells. It is completely eliminated in cloche, moonshine but not in vlad tepes (gata1) mutant embryos. Morpholino (MO) knockdown of the Blf protein results in the defects of morphogenetic movements. Blf-MO-injected embryos (morphants) display shortened and widened axial tissues due to defective convergent extension. Unlike other convergent extension mutants, blf morphants display a split neural tube, resulting in a phenotype similar to the human open neural tube defect spina bifida. In addition, dorsal ectodermal cells delaminate in blf morphants during late somitogenesis. We propose a model explaining the role of blf in convergent extension and neurulation. We conclude that blf plays an important role in regulating morphogenetic movements during gastrulation and neurulation while its role in hematopoiesis may be redundant.

  19. Molecular excitation in the Eagle nebula's fingers

    NASA Astrophysics Data System (ADS)

    Schuller, F.; Leurini, S.; Hieret, C.; Menten, K. M.; Philipp, S. D.; Güsten, R.; Schilke, P.; Nyman, L.-Å.

    2006-08-01

    Context: .The M 16 nebula is a relatively nearby Hii region, powered by O stars from the open cluster NGC 6611, which borders to a Giant Molecular Cloud. Radiation from these hot stars has sculpted columns of dense obscuring material on a few arcmin scales. The interface between these pillars and the hot ionised medium provides a textbook example of a Photodissociation Region (PDR). Aims: .To constrain the physical conditions of the atomic and molecular material with submillimeter spectroscopic observations. Methods: .We used the APEX submillimeter telescope to map a ˜ 3'×3' region in the CO J= 3-2, 4-3 and 7-6 rotational lines, and a subregion in atomic carbon lines. We also observed C18O(3-2) and CO(7-6) with longer integrations on five peaks found in the CO(3-2) map. The large scale structure of the pillars is derived from the molecular lines' emission distribution. We estimate the magnitude of the velocity gradient at the tips of the pillars and use LVG modelling to constrain their densities and temperatures. Excitation temperatures and carbon column densities are derived from the atomic carbon lines. Results: .The atomic carbon lines are optically thin and excitation temperatures are of order 60 K to 100 K, well consistent with observations of other Hii region-molecular cloud interfaces. We derive somewhat lower temperatures from the CO line ratios, of order 40 K. The Ci/CO ratio is around 0.1 at the fingers tips.

  20. Child labour. Refuting the "nimble fingers" argument.

    PubMed

    1996-01-01

    According to an International Labor Organization (ILO) study, approximately 130,000 children work in India's hand-knotted carpet industry. In one-loom enterprises, children comprise 14% of all weavers; in businesses with five or more looms, this rate increases to 33%. India's Factories Act, which applies costly health, safety, and labor regulations to larger firms, has led to a proliferation of cottage industries. The finding that children are more likely to work on low-quality rather than highest-quality carpets refutes the "nimble fingers" argument used by apologists of child labor. Although child and adult weavers have similar productivity, children earn less while apprentices than trained weavers and serve to depress wages throughout the industry. According to ILO estimates, replacing the 22% of the work force currently occupied by children with adults would cause wages to rise by about 5%. The overall savings in production costs from the use of child labor are very small when compared to the foreign retail price of the carpets, which is often four times the Indian export price. The ILO has urged an international approach to the elimination of child labor, in which all carpet-producing countries simultaneously implement a no-child-labor strategy to avoid placing any one country at a competitive disadvantage. Given the thousands of cottages where one or two carpets are woven per year, strategies such as labelling and regulation are likely to be ineffective. Solutions that address the general problems of poverty, while developing alternative sources of education and employment, are most likely to be effective in reducing child labor in countries such as India.