Science.gov

Sample records for high-heat flux electronics

  1. High heat flux cooling for spacecraft electronics

    SciTech Connect

    Leland, J.E.; Chow, L.C. )

    1991-01-05

    An experimental investigation of flow boiling in a curved channel has been performed to ascertain its value in electronics cooling applications. Results have been obtained for flow velocities of 1 to 5 m/s and subcooling of 0.5 to 40 K. These results were compared to those of straight channel under identical velocity and subcooling conditions. The critical heat flux of the curved channel was found to be greater than that of the straight channel. In some cases the increase was found to be marginal, however. An unexplained temperature shift in the nucleate boiling regime was experienced during some experiments. Because this shift only occurred for the first test of the day, it is thought to be related to the incipience phenomenon often experienced in pool boiling experiments. Finally, true incipience overshoot and nucleate boiling regime hysteresis were found to be negligible.

  2. Microgravity experiments on boiling and applications: research activity of advanced high heat flux cooling technology for electronic devices in Japan.

    PubMed

    Suzuki, Koichi; Kawamura, Hiroshi

    2004-11-01

    Research and development on advanced high heat flux cooling technology for electronic devices has been carried out as the Project of Fundamental Technology Development for Energy Conservation, promoted by the New Energy and Industrial Technology Development Organization of Japan (NEDO). Based on the microgravity experiments on boiling heat transfer, the following useful results have obtained for the cooling of electronic devices. In subcooled flow boiling in a small channel, heat flux increases considerably more than the ordinary critical heat flux with microbubble emission in transition boiling, and dry out of the heating surface is disturbed. Successful enhancement of heat transfer is achieved by a capillary effect from grooved surface dual subchannels on the liquid supply. The critical heat flux increases 30-40 percent more than for ordinary subchannels. A self-wetting mechanism has been proposed, following investigation of bubble behavior in pool boiling of binary mixtures under microgravity. Ideas and a new concept have been proposed for the design of future cooling system in power electronics.

  3. Conceptual Design of Vacuum Chamber for testing of high heat flux components using electron beam as a source

    NASA Astrophysics Data System (ADS)

    Khan, M. S.; Swamy, Rajamannar; Khirwadkar, S. S.; Divertors Division, Prototype

    2012-11-01

    A conceptual design of vacuum chamber is proposed to study the thermal response of high heat flux components under energy depositions of the magnitude and durations expected in plasma fusion devices. It is equipped with high power electron beam with maximum beam power of 200 KW mounted in a stationary horizontal position from back side of the chamber. The electron beam is used as a heat source to evaluate the heat removal capacity, material performance under thermal loads & stresses, thermal fatigue etc on actively cooled mock - ups which are mounted on a flange system which is the front side door of the chamber. The tests mock - ups are connected to a high pressure high temperature water circulation system (HPHT-WCS) operated over a wide range of conditions. The vacuum chamber consists of different ports at different angles to view the mock -up surface available for mock -up diagnostics. The vacuum chamber is pumped with different pumps mounted on side ports of the chamber. The chamber is shielded from X - rays which are generated inside the chamber when high-energy electrons are incident on the mock-up. The design includes development of a conceptual design with theoretical calculations and CAD modelling of the system using CATIA V5. These CAD models give an outline on the complete geometry of HHF test chamber, fabrication challenges and safety issues. FEA analysis of the system has been performed to check the structural integrity when the system is subjected to structural & thermal loads.

  4. Floating Refrigerant Loop Based on R-134a Refrigerant Cooling of High-Heat Flux Electronics

    SciTech Connect

    Lowe, K.T.

    2005-10-07

    The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal control project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, ''Methods and Apparatus for Thermal Management of Vehicle Systems and Components'' [1], and patent pending, ''Floating Loop System for Cooling Integrated Motors and Inverters Using Hot Liquid Refrigerant'' [2]. The floating-loop system provides a large coefficient of performance (COP) for hybrid-drive component cooling. This loop (based on R-134a) is integrated with a vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because the temperature requirements for cooling of power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows the floating loop to run without the need for the compressor and only needs a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also provide a high COP, a flat-temperature profile, and low-pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. The COP for the tested floating-loop system ranges from 40-45, as compared to a typical AC system COP of about 2-4. The estimated required waste-heat load for future hybrid applications is 5.5 kW and the existing system could be

  5. Structures for handling high heat fluxes

    NASA Astrophysics Data System (ADS)

    Watson, R. D.

    1990-12-01

    The divertor is reconized as one of the main performance limiting components for ITER. This paper reviews the critical issues for structures that are designed to withstand heat fluxes > 5 MW/m 2. High velocity, sub-cooled water with twisted tape inserts for enhanced heat transfer provides a critical heat flux limit of 40-60 MW/m 2. Uncertainties in physics and engineering heat flux peaking factors require that the design heat flux not exceed 10 MW/m 2 to maintain an adequate burnout safety margin. Armor tiles and heat sink materials must have a well matched thermal expansion coefficient to minimize stresses. The divertor lifetime from sputtering erosion is highly uncertain. The number of disruptions specified for ITER must be reduced to achieve a credible design. In-situ plasma spray repair with thick metallic coatings may reduce the problems of erosion. Runaway electrons in ITER have the potential to melt actively cooled components in a single event. A water leak is a serious accident because of steam reactions with hot carbon, beryllium, or tungsten that can mobilize large amounts of tritium and radioactive elements. If the plasma does not shutdown immediately, the divertor can melt in 1-10 s after a loss of coolant accident. Very high reliability of carbon tile braze joints will be required to achieve adequate safety and performance goals. Most of these critical issues will be addressed in the near future by operation of the Tore Supra pump limiters and the JET pumped divertor. An accurate understanding of the power flow out of edge of a DT burning plasma is essential to successful design of high heat flux components.

  6. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  7. High heat flux single phase heat exchanger

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A.; Izenson, Michael G.

    1990-01-01

    This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

  8. High heat flux loop heat pipes

    NASA Technical Reports Server (NTRS)

    North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

    1997-01-01

    Loop heat pipes (LHPs) can transport very large thermal power loads over long distances, through flexible, small diameter tubes against gravitational heads. In order to overcome the evaporator limit of LHPs, which is of about 0.07 MW/sq m, work was carried out to improve the efficiency by threefold to tenfold. The vapor passage geometry for the high heat flux conditions is shown. A bidisperse wick material within the circumferential vapor passages was used. Along with heat flux enhancement, several underlying issues were demonstrated, including the fabrication of bidisperse powder with controlled properties and the fabrication of a device geometry capable of replacing vapor passages with bidisperse powder.

  9. High heat flux transport by microbubble emission boiling

    NASA Astrophysics Data System (ADS)

    Suzuki, Koichi

    2007-10-01

    In highly subcooled flow boiling, coalescing bubbles on the heating surface collapse to many microbubbles in the beginning of transition boiling and the heat flux increases higher than the ordinary critical heat flux. This phenomenon is called Microbubble Emission Boiling, MEB. It is generated in subcooled flow boiling and the maximum heat flux reaches about 1 kW/cm2(10 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s for a small heating surface of 10 mm×10 mm which is placed at the bottom surface of horizontal rectangular channel. The high pressure in the channel is observed at collapse of the coalescing bubbles and it is closely related the size of coalescing bubbles. Periodic pressure waves are observed in MEB and the heat flux increases linearly in proportion to the pressure frequency. The frequency is considered the frequency of liquid-solid exchange on the heating surface. For the large sized heating surface of 50 mm length×20 mm width, the maximum heat flux obtained is 500 W/cm2 (5 MW/m2) at liquid subcooling of 40 K and liquid velocity of 0.5 m/s. This is considerably higher heat flux than the conventional cooling limit in power electronics. It is difficult to remove the high heat flux by MEB for a longer heating surface than 50 mm by single channel type. A model of advanced cooling device is introduced for power electronics by subcooled flow boiling with impinging jets. Themaxumum cooling heat flux is 500 W/cm2 (5 MW/m2). Microbubble emission boiling is useful for a high heat flux transport technology in future power electronics used in a fuel-cell power plant and a space facility.

  10. Applicability of copper alloys for DEMO high heat flux components

    NASA Astrophysics Data System (ADS)

    Zinkle, Steven J.

    2016-02-01

    The current state of knowledge of the mechanical and thermal properties of high-strength, high conductivity Cu alloys relevant for fusion energy high heat flux applications is reviewed, including effects of thermomechanical and joining processes and neutron irradiation on precipitation- or dispersion-strengthened CuCrZr, Cu-Al2O3, CuNiBe, CuNiSiCr and CuCrNb (GRCop-84). The prospects for designing improved versions of wrought copper alloys and for utilizing advanced fabrication processes such as additive manufacturing based on electron beam and laser consolidation methods are discussed. The importance of developing improved structural materials design criteria is also noted.

  11. High heat flux engineering in solar energy applications

    SciTech Connect

    Cameron, C.P.

    1993-07-01

    Solar thermal energy systems can produce heat fluxes in excess of 10,000 kW/m{sup 2}. This paper provides an introduction to the solar concentrators that produce high heat flux, the receivers that convert the flux into usable thermal energy, and the instrumentation systems used to measure flux in the solar environment. References are incorporated to direct the reader to detailed technical information.

  12. Baseline high heat flux and plasma facing materials for fusion

    NASA Astrophysics Data System (ADS)

    Ueda, Y.; Schmid, K.; Balden, M.; Coenen, J. W.; Loewenhoff, Th.; Ito, A.; Hasegawa, A.; Hardie, C.; Porton, M.; Gilbert, M.

    2017-09-01

    In fusion reactors, surfaces of plasma facing components (PFCs) are exposed to high heat and particle flux. Tungsten and Copper alloys are primary candidates for plasma facing materials (PFMs) and coolant tube materials, respectively, mainly due to high thermal conductivity and, in the case of tungsten, its high melting point. In this paper, recent understandings and future issues on responses of tungsten and Cu alloys to fusion environments (high particle flux (including T and He), high heat flux, and high neutron doses) are reviewed. This review paper includes; Tritium retention in tungsten (K. Schmid and M. Balden), Impact of stationary and transient heat loads on tungsten (J.W. Coenen and Th. Loewenhoff), Helium effects on surface morphology of tungsten (Y. Ueda and A. Ito), Neutron radiation effects in tungsten (A. Hasegawa), and Copper and copper alloys development for high heat flux components (C. Hardie, M. Porton, and M. Gilbert).

  13. High heat flux measurements and experimental calibrations/characterizations

    NASA Technical Reports Server (NTRS)

    Kidd, Carl T.

    1992-01-01

    Recent progress in techniques employed in the measurement of very high heat-transfer rates in reentry-type facilities at the Arnold Engineering Development Center (AEDC) is described. These advances include thermal analyses applied to transducer concepts used to make these measurements; improved heat-flux sensor fabrication methods, equipment, and procedures for determining the experimental time response of individual sensors; performance of absolute heat-flux calibrations at levels above 2,000 Btu/cu ft-sec (2.27 kW/cu cm); and innovative methods of performing in-situ run-to-run characterizations of heat-flux probes installed in the test facility. Graphical illustrations of the results of extensive thermal analyses of the null-point calorimeter and coaxial surface thermocouple concepts with application to measurements in aerothermal test environments are presented. Results of time response experiments and absolute calibrations of null-point calorimeters and coaxial thermocouples performed in the laboratory at intermediate to high heat-flux levels are shown. Typical AEDC high-enthalpy arc heater heat-flux data recently obtained with a Calspan-fabricated null-point probe model are included.

  14. Copper alloys for high heat flux structure applications

    SciTech Connect

    Zinkle, S.J.; Fabritsiev, S.A.

    1994-09-01

    The mechanical and physical properties of copper alloys are reviewed and compared with the requirements for high heat flux structural applications in fusion reactors. High heat flux structural materials must possess a combination of high thermal conductivity and high mechanical strength. The three most promising copper alloys at the present time are oxide dispersion-strengthened copper (Cu-Al{sub 2}O{sub 3}) and two precipitation-hardened copper alloys (Cu-Cr-Zr and Cu-Ni-Be). These three alloys are capable of room temperature yield strengths >400 MPa and thermal conductivities up to 350 W/m-K. All of these alloys require extensive cold working to achieve their optimum strength. Precipitation-hardened copper alloys such Cu-Cr-Zr are susceptible to softening due to precipitate overaging and recrystallization during brazing, whereas the dislocation structure in Cu-Al{sub 2}O{sub 3} remains stabilized during typical high temperature brazing cycles. All three alloys exhibit good resistance to irradiation-induced softening and void swelling at temperatures below 300{degrees}C. The precipitation-strengthened allows typically soften during neutron irradiation at temperatures above about 300{degrees}C and therefore should only be considered for applications operating at temperatures <300{degrees}C. Dispersion-strengthened copper may be used up to temperatures in excess of 500{degrees}C. Based on the available data, dispersion-strengthened copper (Cu-Al{sub 2}O{sub 3}) is considered to be the best candidate for high heat flux structural applications.

  15. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  16. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y203 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-20 percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  17. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y2O3 specimens survived 3000 of the 0.5 sec cycles with falling. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 1 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-2O percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  18. Vapor Shielding of Solid Targets Exposed to High Heat Flux

    NASA Astrophysics Data System (ADS)

    Pshenov, A. A.; Eksaeva, A. A.; Krasheninnikov, S. I.; Marenkov, E. D.

    The thickness of Tungsten monoblocks composing the future ITER divertor is supposed to be 8 mm only. Therefore, severe erosion caused by high heat fluxes during transients, such as Type I ELMs and disruptions, is a limiting factor to PFCs lifespan. Under the influence of extreme heat fluxes expected during ITER transients serious surface modification of the Tungsten monoblocks is anticipated. Moreover, melting of a thin surface layer is likely to happen. Melt motion contributes seriously to the material erosion. The other sources of erosion are melt splashing, in the form of droplet ejection, and evaporation. These mechanics lead to a cold dense secondary plasma region formation near the irradiated surface. Intense re-radiation of the incoming plasma flow energy in the secondary plasma layer results in a significant reduction of the heat flux reaching the target surface. Accounting for this vapor shielding effect is essential to estimate the surface erosion under influence of intense plasma flow properly. In this paper a simple model capable of reproducing one of the key features of vapor shielding, namely the saturation of the energy absorbed by the target, is proposed. This model allows for an approximate analytical solution that indicates parameters the saturation energy depends on. The model is validated against the experimental data obtained at MK-200 pulse plasma accelerator.

  19. Structural design criteria for high heat flux components.

    SciTech Connect

    Majumdar, S.

    1999-07-14

    The high temperature design rules of the ITER Structural Design Criteria (ISDC), are applied to first wall designs with high heat flux. The maximum coolant pressure and surface heat flux capabilities are shown to be determined not only by the mechanical properties of the first wall material but also by the details of the blanket design. In a high power density self-cooled lithium blanket, the maximum primary stress in the first wall is controlled by many of the geometrical parameters of the blanket, such as, first wall span, first wall curvature, first wall thickness, side wall thickness, and second wall thickness. The creep ratcheting lifetime of the first wall is also shown to be controlled by many of the same geometrical parameters as well as the coolant temperature. According to most high temperature design codes, the time-dependent primary membrane stress allowable are based on the average temperature (ignoring thermal stress). Such a procedure may sometimes be unconservative, particularly for embrittled first walls with large temperature gradients. The effect of secondary (thermal) stresses on the accumulation of creep deformation is illustrated with a vanadium alloy flat plate first wall design.

  20. Recent High Heat Flux Tests on W-Rod-Armored Mockups

    SciTech Connect

    NYGREN,RICHARD E.; YOUCHISON,DENNIS L.; MCDONALD,JIMMIE M.; LUTZ,THOMAS J.; MISZKIEL,MARK E.

    2000-07-18

    In the authors initial high heat flux tests on small mockups armored with W rods, done in the small electron beam facility (EBTS) at Sandia National Laboratories, the mockups exhibited excellent thermal performance. However, to reach high heat fluxes, they reduced the heated area to only a portion ({approximately}25%) of the sample. They have now begun tests in their larger electron beam facility, EB 1200, where the available power (1.2 MW) is more than enough to heat the entire surface area of the small mockups. The initial results indicate that, at a given power, the surface temperatures of rods in the EB 1200 tests is somewhat higher than was observed in the EBTS tests. Also, it appears that one mockup (PW-10) has higher surface temperatures than other mockups with similar height (10mm) W rods, and that the previously reported values of absorbed heat flux on this mockup were too high. In the tests in EB 1200 of a second mockup, PW-4, absorbed heat fluxes of {approximately}22MW/m{sup 2} were reached but the corresponding surface temperatures were somewhat higher than in EBTS. A further conclusion is that the simple 1-D model initially used in evaluating some of the results from the EBTS testing was not adequate, and 3-D thermal modeling will be needed to interpret the results.

  1. Thermal barrier coatings (TBC's) for high heat flux thrust chambers

    NASA Astrophysics Data System (ADS)

    Bradley, Christopher M.

    -section components has become critical, but at the same time the service conditions have put our best alloy systems to their limits. As a result, implementation of cooling holes and thermal barrier coatings are new advances in hot-section technologies now looked at for modifications to reach higher temperature applications. Current thermal barrier coatings used in today's turbine applications is known as 8%yttria-stabilized zirconia (YSZ) and there are no coatings for current thrust chambers. Current research is looking at the applicability of 8%yttria-stabilized hafnia (YSH) for turbine applications and the implementation of 8%YSZ onto thrust chambers. This study intends to determine if the use of thermal barrier coatings are applicable for high heat flux thrust chambers using industrial YSZ will be advantageous for improvements in efficiency, thrust and longer service life by allowing the thrust chambers to be used more than once.

  2. Extremely high heat fluxes beneath impinging liquid jets

    NASA Astrophysics Data System (ADS)

    Liu, X.; Lienhard, J. H., V.

    1993-05-01

    Measurements of jet-impingement heat fluxes up to 400 MW/sq m were obtained using a specially designed experimental arrangement where a thin metal plate was heated from one side with a plasma arc and cooled from the other side with an unsubmerged impinging water jet produced by a 34 MPa piston pump supplying a large cylindrical plenum. The results of this study, where heating was confined to the stagnation region, show no evidence of a critical heat flux, even up to the maximum power applied. The large fluxes were limited only by wall failure and the power of the heating source, and not by liquid-side thermal resistance.

  3. Liquid jet impingement cooling with diamond substrates for extremely high heat flux applications

    NASA Astrophysics Data System (ADS)

    Lienhard V, John H.; Khounsary, Ali M.

    1993-11-01

    This paper considers the potential of jet/diamond systems for removing localized high heat fluxes. Diamond substrates are compared to other candidate materials. Limits on usable thermal resistances and heat transfer rates are estimated.

  4. Modeling of convective subcooled boiling in microtubes for high heat fluxes

    NASA Astrophysics Data System (ADS)

    Hoffman, Myron A.; Stetson, James D., IV

    1993-02-01

    Cooling systems for very compact electronic components and computer chips are being miniaturized to meet the need for smaller overall packaging. One of the important present directions has been to use laminar flow in very small channels with hydraulic diameters in the sub-millimeter range to get high heat transfer coefficients with low pressure drops. It has been speculated that there might be some advantage to having convective subcooled boiling (SCB) occur in the micro-channels. As a first step in the evaluation of the utility of subcooled boiling in these micro-channels, a model has been developed for subcooled boiling in sub-millimeter diameter microtubes subject to uniform heat flux. This model builds on a previously well-validated computer code for convective subcooled boiling in tubes down to 1.57 mm inner diameter. The basic features of the new microtube model are described and some predictions using this model for 0.3 mm and 0.1 mm microtubes subject to a high heat flux of 10 MW/m2 are given.

  5. High heat flux performance of brazed tungsten macro-brush test mock-up for divertors

    NASA Astrophysics Data System (ADS)

    Patil, Yashashri; Khirwadkar, S. S.; Krishnan, D.; Patel, A.; Tripathi, S.; Singh, K. P.; Belsare, S. M.

    2013-06-01

    Plasma facing components (PFCs) of divertor will be exposed to steady state and transient heat loads up to 20 MW/m2, during operation of ITER-like plasma fusion device. The critical task in fusion research is to design, fabricate and test of PFCs. To withstand high heat loads, PFCs are designed and fabricated in flat tile, mono-block type geometries using tungsten as plasma facing material and CuCrZr alloy is used as a heat sink. These fabricated mock-ups are tested under thermal cyclic heat loads using intense electron beam in pulsed mode. Tungsten macro-brush type of mock-up has been developed by vacuum furnace brazing route. Mock-up was tested to the absorbed heat flux in the range of 0.5-9 MW/m2. Simulation of high heat flux (HHF) test under steady state and cyclic heat loads has been done using ANSYS12 finite element analysis (FEA) software. HHF tests have been successfully performed on the tungsten mock-up.

  6. Light-intensity modulator withstands high heat fluxes

    NASA Technical Reports Server (NTRS)

    Maples, H. G.; Strass, H. K.

    1966-01-01

    Mechanism modulates and controls the intensity of luminous radiation in light beams associated with high-intensity heat flux. This modulator incorporates two fluid-cooled, externally grooved, contracting metal cylinders which when rotated about their longitudinal axes present a circular aperture of varying size depending on the degree of rotation.

  7. 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.

  8. Calibration of High Heat Flux Sensors at NIST

    PubMed Central

    Murthy, A. V.; Tsai, B. K.; Gibson, C. E.

    1997-01-01

    An ongoing program at the National Institute of Standards and Technology (NIST) is aimed at improving and standardizing heat-flux sensor calibration methods. The current calibration needs of U.S. science and industry exceed the current NIST capability of 40 kW/m2 irradiance. In achieving this goal, as well as meeting lower-level non-radiative heat flux calibration needs of science and industry, three different types of calibration facilities currently are under development at NIST: convection, conduction, and radiation. This paper describes the research activities associated with the NIST Radiation Calibration Facility. Two different techniques, transfer and absolute, are presented. The transfer calibration technique employs a transfer standard calibrated with reference to a radiometric standard for calibrating the sensors using a graphite tube blackbody. Plans for an absolute calibration facility include the use of a spherical blackbody and a cooled aperture and sensor-housing assembly to calibrate the sensors in a low convective environment. PMID:27805156

  9. Critical heat flux of subcooled flow boiling with water for high heat flux application

    NASA Astrophysics Data System (ADS)

    Inasaka, Fujio; Nariai, Hideki

    1993-11-01

    Subcooled flow boiling in water is thought to be advantageous in removing high heat load of more than 10 MW/m2. Characteristics of the critical heat flux (CHF), which determines the upper limit of heat removal, are very important for the design of cooling systems. In this paper, studies on subcooled flow boiling CHF, which have been conducted by the authors, are reported. Experiments were conducted using direct current heating of stainless steel tube. For uniform heating conditions, CHF increment in small diameter tubes (1 - 3 mm inside diameter) and the CHF characteristics in tubes with internal twisted tapes were investigated, and also the existing CHF correlations for ordinary tubes (more than 3 mm inside diameter) were evaluated. For peripherally non-uniform heating conditions using the tube, whose wall thickness was partly reduced, the CHF for swirl flow was higher than the CHF under uniform heating conditions with an increase of the non-uniformity factor.

  10. Evaporation on/in Capillary Structures of High Heat Flux Two-Phase Devices

    NASA Technical Reports Server (NTRS)

    Faghri, Amir; Khrustalev, Dmitry

    1996-01-01

    Two-phase devices (heat pipes, capillary pumped loops, loop heat pipes, and evaporators) have become recognized as key elements in thermal control systems of space platforms. Capillary and porous structures are necessary and widely used in these devices, especially in high heat flux and zero-g applications, to provide fluid transport and enhanced heat transfer during vaporization and condensation. However, some unexpected critical phenomena, such as dryout in long heat pipe evaporators and high thermal resistance of loop heat pipe evaporators with high heat fluxes, are possible and have been encountered in the use of two-phase devices in the low gravity environment. Therefore, a detailed fundamental investigation is proposed to better understand the fluid behavior in capillary-porous structures during vaporization at high heat fluxes. The present paper addresses some theoretical aspects of this investigation.

  11. High heat flux issues for plasma-facing components in fusion reactors

    NASA Astrophysics Data System (ADS)

    Watson, Robert D.

    1993-02-01

    Plasma facing components in tokamak fusion reactors are faced with a number of difficult high heat flux issues. These components include: first wall armor tiles, pumped limiters, diverter plates, rf antennae structure, and diagnostic probes. Peak heat fluxes are 15 - 30 MW/m2 for diverter plates, which will operate for 100 - 1000 seconds in future tokamaks. Disruption heat fluxes can approach 100,000 MW/m2 for 0.1 ms. Diverter plates are water-cooled heat sinks with armor tiles brazed on to the plasma facing side. Heat sink materials include OFHC, GlidcopTM, TZM, Mo-41Re, and niobium alloys. Armor tile materials include: carbon fiber composites, beryllium, silicon carbide, tungsten, and molybdenum. Tile thickness range from 2 - 10 mm, and heat sinks are 1 - 3 mm. A twisted tape insert is used to enhance heat transfer and increase the burnout safety margin from critical heat flux limits to 50 - 60 MW/m2 with water at 10 m/s and 4 MPa. Tests using rastered electron beams have shown thermal fatigue failures from cracks at the brazed interface between tiles and the heat sink after only 1000 cycles at 10 - 15 MW/m2. These fatigue lifetimes need to be increased an order of magnitude to meet future requirements. Other critical issues for plasma facing components include: surface erosion from sputtering and disruption erosion, eddy current forces and runaway electron impact from disruptions, neutron damage, tritium retention and release, remote maintenance of radioactive components, corrosion-erosion, and loss-of-coolant accidents.

  12. High heat flux testing capabilities at Sandia National Laboratories - New Mexico

    SciTech Connect

    Youchison, D.L.; McDonald, J.M.; Wold, L.S.

    1994-12-31

    High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories - New Mexico. This facility, which is owned by the United States Department of Energy, has been in operation for over 17 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion, tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton and the DIII-D tokamak at General Atomics, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux-burnout tests, braze reliability tests and safety related tests. The objective of this article is to provide a brief overview of the high heat flux testing capabilities at the PMTF and describe a few of the experiments performed over the last year.

  13. Recent results of high heat flux testing at the Plasma Materials Test Facility

    NASA Astrophysics Data System (ADS)

    Youchison, Dennis L.; Watson, Robert D.; Marshall, Theron D.; McDonald, Jimmie M.

    1996-11-01

    High heat flux testing for the US fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratory. This facility, an official Department of Energy User Facility, has been in operation for over 15 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world's magnetic fusion tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor at Princeton, the DIII-D tokamak at General Atomics, and Alcator C-Mod at MIT, components for international experiments like TEXTOR, Tore- Supra, and Jet also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux burnout testes, braze reliability tests, and safety related tests. The program's main focus now is on testing of beryllium and tungsten armor tiles bonded to divertor, limiter, and first wall components for the International Thermonuclear Experimental Reactor (ITER). The ITER project is a collaboration among the US, EU, RF, and Japanese fusion programs. This article provides a brief overview of the high heat flux testing capabilities at the PMTF, and describes some recent test results.

  14. Recent results of high heat flux testing at the Plasma Materials Test Facility

    SciTech Connect

    Youchison, D.L.; Watson, R.D.; Marshall, T.D.; McDonald, J.M.

    1996-12-31

    High heat flux testing for the United States fusion power program is the primary mission of the Plasma Materials Test Facility (PMTF) located at Sandia National Laboratories in Albuquerque, New Mexico. This facility, an official Department of Energy User Facility, has been in operation for over 15 years and has provided much of the high heat flux data used in the design and evaluation of plasma facing components for many of the world`s magnetic fusion tokamak experiments. In addition to domestic tokamaks such as Tokamak Fusion Test Reactor (TFTR) at Princeton, the DIII-D tokamak pt General Atomics, and Alcator C-Mod at MIT, components for international experiments like TEXTOR, Tore-Supra, and JET also have been tested at the PMTF. High heat flux testing spans a wide spectrum including thermal shock tests on passively cooled materials, thermal response and thermal fatigue tests on actively cooled components, critical heat flux burnout tests, braze reliability tests, and safety related tests. The program`s main focus now is on testing of beryllium and tungsten armor tiles bonded to divertor, limiter, and first wall components for the International Thermonuclear Experimental Reactor (ITER). The ITER project is a collaboration among the US, EU, RF, and Japanese fusion programs. This article provides a brief overview of the high heat flux testing capabilities at the PMTF, and describes some recent test results.

  15. Monitoring Delamination of Thermal Barrier Coating During Interrupted High-Heat Flux Laser Testing Using Upconversion Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    Upconversion luminescence imaging of thermal barrier coatings (TBCs) has been shown to successfully monitor TBC delamination progression during interrupted furnace cycling. However, furnace cycling does not adequately model engine conditions where TBC-coated components are subjected to significant heat fluxes that produce through-thickness temperature gradients that may alter both the rate and path of delamination progression. Therefore, new measurements are presented based on luminescence imaging of TBC-coated specimens subjected to interrupted high-heat-flux laser cycling exposures that much better simulate the thermal gradients present in engine conditions. The TBCs tested were deposited by electron-beam physical vapor deposition (EB-PVD) and were composed of 7wt% yttria-stabilized zirconia (7YSZ) with an integrated delamination sensing layer composed of 7YSZ co-doped with erbium and ytterbium (7YSZ:Er,Yb). The high-heat-flux exposures that produce the desired through-thickness thermal gradients were performed using a high power CO2 laser operating at a wavelength of 10.6 microns. Upconversion luminescence images revealed the debond progression produced by the cyclic high-heat-flux exposures and these results were compared to that observed for furnace cycling.

  16. Design and performance of vacuum system for high heat flux test facility

    NASA Astrophysics Data System (ADS)

    Swamy Kidambi, Rajamannar; Mokaria, Prakash; Khirwadkar, Samir; Belsare, Sunil; Khan, M. S.; Patel, Tushar; Krishnan, Deepu S.

    2017-04-01

    High heat flux test facility (HHFTF) at IPR is used for testing thermal performance of plasma facing materials or components. It consists of various subsystems like vacuum system, high power electron beam system, diagnostic and calibration system, data acquisition and control system and high pressure high temperature water circulation system. Vacuum system consists of large D-shaped chamber, target handling system, pumping systems and support structure. The net volume of vacuum chamber is 5 m3 was maintained at the base pressure of the order of 10-6 mbar for operation of electron gun with minimum beam diameter which is achieved with turbo-molecular pump (TMP) and cryo pump. A variable conductance gate valve is used for maintaining required vacuum in the chamber. Initial pumping of the chamber was carried out by using suitable rotary and root pumps. PXI and PLC based faster real time data acquisition and control system is implemented for performing the various operations like remote operation, online vacuum data measurements, display and status indication of all vacuum equipments. This paper describes in detail the design and implementation of various vacuum system for HHFTF.

  17. High heat flux testing of CFC composites for the tokamak physics experiment

    NASA Astrophysics Data System (ADS)

    Valentine, P. G.; Nygren, R. E.; Burns, R. W.; Rocket, P. D.; Colleraine, A. P.; Lederich, R. J.; Bradley, J. T.

    1996-10-01

    High heat flux (HHF) testing of carbon fiber reinforced carbon composites (CFC's) was conducted under the General Atomics program to develop plasma-facing components (PFC's) for Princeton Plasma Physics Laboratory's tokamak physics experiment (TPX). As part of the process of selecting TPX CFC materials, a series of HHF tests were conducted with the 30 kW electron beam test system (EBTS) facility at Sandia National Laboratories, and with the plasma disruption simulator I (PLADIS-I) facility at the University of New Mexico. The purpose of the tests was to make assessments of the thermal performance and erosion behavior of CFC materials. Tests were conducted with 42 different CFC materials. In general, the CFC materials withstood the rapid thermal pulse environments without fracturing, delaminating, or degrading in a non-uniform manner; significant differences in thermal performance, erosion behavior, vapor evolution, etc. were observed and preliminary findings are presented below. The CFC's exposed to the hydrogen plasma pulses in PLADIS-I exhibited greater erosion rates than the CFC materials exposed to the electron-beam pulses in EBTS. The results obtained support the continued consideration of a variety of CFC composites for TPX PFC components.

  18. Liquid jet impingement cooling with diamond substrates for extremely high heat flux applications

    SciTech Connect

    Lienhard, J.H. V; Khounsary, A.M.

    1993-09-01

    The combination of impinging jets and diamond substrates may provide an effective solution to a class of extremely high heat flux problems in which very localized heat loads must be removed. Some potential applications include the cooling of high-heat-load components in synchrotron x-ray, fusion, and semiconductor laser systems. Impinging liquid jets are a very effective vehicle for removing high heat fluxes. The liquid supply arrangement is relatively simple, and low thermal resistances can be routinely achieved. A jet`s cooling ability is a strong function of the size of the cooled area relative to the jet diameter. For relatively large area targets, the critical heat fluxes can approach 20 W/mm{sup 2}. In this situation, burnout usually originates at the outer edge of the cooled region as increasing heat flux inhibits the liquid supply. Limitations from liquid supply are minimized when heating is restricted to the jet stagnation zone. The high stagnation pressure and high velocity gradients appear to suppress critical flux phenomena, and fluxes of up to 400 W/mm{sup 2} have been reached without evidence of burnout. Instead, the restrictions on heat flux are closely related to properties of the cooled target. Target properties become an issue owing to the large temperatures and large temperature gradients that accompany heat fluxes over 100 W/mm{sup 2}. These conditions necessitate a target with both high thermal conductivity to prevent excessive temperatures and good mechanical properties to prevent mechanical failures. Recent developments in synthetic diamond technology present a possible solution to some of the solid-side constraints on heat flux. Polycrystalline diamond foils can now be produced by chemical vapor deposition in reasonable quantity and at reasonable cost. Synthetic single crystal diamonds as large as 1 cm{sup 2} are also available.

  19. Modeling of a heat sink and high heat flux vapor chamber

    NASA Astrophysics Data System (ADS)

    Vadnjal, Aleksander

    An increasing demand for a higher heat flux removal capability within a smaller volume for high power electronics led us to focus on a novel cold plate design. A high heat flux evaporator and micro channel heat sink are the main components of a cold plate which is capable of removing couple of 100 W/cm2. In order to describe performance of such porous media device a proper modeling has to be addressed. A universal approach based on the volume average theory (VAT) to transport phenomena in porous media is shown. An approach on how to treat the closure for momentum and energy equations is addressed and a proper definition for friction factors and heat transfer coefficients are discussed. A numerical scheme using a solution to Navier-Stokes equations over a representative elementary volume (REV) and the use of VAT is developed to show how to compute friction factors and heat transfer coefficients. The calculation show good agreement with the experimental data. For the heat transfer coefficient closure, a proper average for both fluid and solid is investigated. Different types of heating are also investigated in order to determine how it influences the heat transfer coefficient. A higher heat fluxes in small area condensers led us to the micro channels in contrast to the classical heat fin design. A micro channel can have various shapes to enhance heat transfer, but the shape that will lead to a higher heat flux removal with a moderate pumping power needs to be determined. The standard micro-channel terminology is usually used for channels with a simple cross section, e.g. square, round, triangle, etc., but here the micro channel cross section is going to be expanded to describe more complicated and interconnected micro scale channel cross sections. The micro channel geometries explored are pin fins (in-line and staggered) and sintered porous micro channels. The problem solved here is a conjugate problem involving two heat transfer mechanisms; (1) porous media

  20. Institute for High Heat Flux Removal (IHHFR). Phases I, II, and III

    SciTech Connect

    Boyd, Ronald D.

    2014-08-31

    The IHHFR focused on interdisciplinary applications as it relates to high heat flux engineering issues and problems which arise due to engineering systems being miniaturized, optimized, or requiring increased high heat flux performance. The work in the IHHFR focused on water as a coolant and includes: (1) the development, design, and construction of the high heat flux flow loop and facility; (2) test section development, design, and fabrication; and, (3) single-side heat flux experiments to produce 2-D boiling curves and 3-D conjugate heat transfer measurements for single-side heated test sections. This work provides data for comparisons with previously developed and new single-side heated correlations and approaches that address the single-side heated effect on heat transfer. In addition, this work includes the addition of single-side heated circular TS and a monoblock test section with a helical wire insert. Finally, the present work includes: (1) data base expansion for the monoblock with a helical wire insert (only for the latter geometry), (2) prediction and verification using finite element, (3) monoblock model and methodology development analyses, and (4) an alternate model development for a hypervapotron and related conjugate heat transfer controlling parameters.

  1. High heat flux erosion of carbon fibre composite materials in the TEXTOR tokamak.

    SciTech Connect

    Hassanein, A.

    1998-03-10

    During plasma disruptions, ELMs, or vertical displacement events (VDEs) high transient heat loads to the plasma facing materials an cause damage such as thermal erosion, cracking, or melting. Self shielding processes, which take place when a material surface is exposed to a high heat flux from an incident plasma, can lead to a reduction of the deposited energy. Experiments using the fast pneumatic probe of the TEXTOR tokamak were carried out to investigate these effects. The materials tested were carbon fibre reinforced materials with and without Si-addition. The probe with the material specimens was introduced into the edge plasma up to a depth of 9 cm in front of the ALT41 main limiter with a residence time of 80 ms. After the repeated exposure to the TEXTOR-plasma, the material specimens were examined by profilometry and electron microscopy to determine the damage and erosion. It was found that only a very limited zone of the probe tip of about 2.5 mm extension in radial direction showed erosion. The maximum erosion was observed at the very tip of the probe with approx. 30 {micro}m per exposure. The results of the erosion quantification are compared with the results from numerical simulations and from plasma diagnostic measurements during the exposure of the specimens.

  2. GRCop-84: A High Temperature Copper-based Alloy For High Heat Flux Applications

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2005-01-01

    While designed for rocket engine main combustion chamber liners, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) offers potential for high heat flux applications in industrial applications requiring a temperature capability up to approximately 700 C (1292 F). GRCop-84 is a copper-based alloy with excellent elevated temperature strength, good creep resistance, long LCF lives and enhanced oxidation resistance. It also has a lower thermal expansion than copper and many other low alloy copper-based alloys. GRCop-84 can be manufactured into a variety of shapes such as tubing, bar, plate and sheet using standard production techniques and requires no special production techniques. GRCop-84 forms well, so conventional fabrication methods including stamping and bending can be used. GRCop-84 has demonstrated an ability to be friction stir welded, brazed, inertia welded, diffusion bonded and electron beam welded for joining to itself and other materials. Potential applications include plastic injection molds, resistance welding electrodes and holders, permanent metal casting molds, vacuum plasma spray nozzles and high temperature heat exchanger applications.

  3. Behavior of Brazed W/Cu Mockup Under High Heat Flux Loads

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Lian, Youyun; Liu, Xiang

    2014-03-01

    In order to transfer the heat from the armor to the coolant, tungsten has to be connected with a copper heat sink. The joint technology is the most critical issue for manufacturing plasma facing components. Consequently, the reliability of the joints should be verified by a great number of high-heat-flux (HHF) tests to simulate the real load conditions. W/Cu brazed joint technology with sliver free filler metal CuMnNi has been developed at Southwestern Institute of Physics (SWIP). Screening and thermal fatigue tests of one small-scale flat tile W/CuCrZr mockup were performed on a 60 kW electron-beam Material testing scenario (EMS-60) constructed recently at SWIP. The module successfully survived screening test with the absorbed power density (Pabs) of 2 MW/m2 to 10 MW/m2 and the following 1000 cycles at Pabs of 7.2 MW/m2 without hot spots and overheating zones during the whole test campaign. Metallurgy and SEM observations did not find any cracks at both sides and the interface, indicating a good bonding of W and CuCrZr alloy. In addition, finite element simulations by ANSYS 12.0 under experimental load conditions were performed and compared with experimental results.

  4. High-Heat-Flux Cyclic Durability of Thermal and Environmental Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Ghosn, Louis L.; Miller, Robert A.

    2007-01-01

    Advanced ceramic thermal and environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect the engine components and further raise engine temperatures. For the supersonic vehicles currently envisioned in the NASA fundamental aeronautics program, advanced gas turbine engines will be used to provide high power density thrust during the extended supersonic flight of the aircraft, while meeting stringent low emission requirements. Advanced ceramic coating systems are critical to the performance, life and durability of the hot-section components of the engine systems. In this work, the laser and burner rig based high-heat-flux testing approaches were developed to investigate the coating cyclic response and failure mechanisms under simulated supersonic long-duration cruise mission. The accelerated coating cracking and delamination mechanism under the engine high-heat-flux, and extended supersonic cruise time conditions will be addressed. A coating life prediction framework may be realized by examining the crack initiation and propagation in conjunction with environmental degradation under high-heat-flux test conditions.

  5. On the use of flat tile armour in high heat flux components

    NASA Astrophysics Data System (ADS)

    Merola, M.; Vieider, G.

    1998-10-01

    The possibility to have a flat tile geometry for those high heat flux components subjected to a convective heat flux (namely the divertor dump target, lower vertical target, and the limiter) has been investigated. Because of the glancing incidence of the power load, if an armour tile falls off an extremely high heat flux hits the leading edge of the adjacent tile. As a result a rapid temperature increase occurs in the armour-heat sink joint. The heat flux to the water coolant also increases rapidly up to a factor of 1.7 and 2.3 for a beryllium and CFC armour, respectively, thus causing possible critical heat flux problems. Thermal stresses in the armour-heat sink joint double in less than 0.4 s and triplicate after 1 s thus leading to a possible cascade failure. Therefore the use of a flat tile geometry for these components does not seem to be appropriate. In this case a monoblock geometry gives a much more robust solution.

  6. Experimental and Numerical Characterization of High Heat Fluxes During Transient Blackbody Calibrations

    NASA Technical Reports Server (NTRS)

    Abdelmessih, Amanie N.; Horn, Thomas J.

    2008-01-01

    High heat fluxes are encountered in numerous applications, such as hypersonic vehicles in flight, fires, and engines, Calibration of heat flux gages may be performed in a dual cavity cylindrical blackbody resulting in a transient calibration environment. To characterize the transient heat fluxes. experiments were performed on a dual cavity cylindrical blackbody at nominal temperatures varying from 800 C to 1900 C in increments of 100 C. Based on experiments, the optimum heat flux sensor insertion location as measured from the center partition was determined. The pre-insertion steady state axial temperature profile is compared experimentally, numerically, and analytically. The effect of convection in the blackbody cavity during the insertion is calculated and found to be less than 2 per cent. Also, an empirical correlation for predicting the emissivity of the blackbody is included. Detailed transient thermal models have been developed to simulate the heat flux calibration process at two extreme fluxes. The high (1MW/sq m) and relatively low (70 kw/sq m) fluxes are reported in this article. The transient models show the effect of inserting a heat flux gage at room temperature on the thermal equilibrium of the blackbody at 1800 C and 800 C nominal temperatures, respectively. Also, heat flux sensor outputs are derived from computed sensor temperature distributions and compared to experimental results.

  7. Two-phase spray cooling with water/2-propanol binary mixtures for high heat flux focal source

    NASA Astrophysics Data System (ADS)

    Obuladinne, Sai Sujith

    Two-phase spray cooling has been an emerging thermal management technique offering high heat transfer coefficients and critical heat flux levels, near-uniform surface temperatures, and efficient coolant usage that enables to design of compact and lightweight systems. Due to these capabilities, spray cooling is a promising approach for high heat flux applications in computing, power electronics, and optics. Two-phase spray cooling inherently depends on saturation temperature-pressure relationships of the working fluid to take advantage of high heat transfer rates associated with liquid-vapor phase change. When a certain application requires strict temperature and/or pressure conditions, thermo-physical properties of the working fluid play a critical role in attaining proper efficiency, reliability, or packaging structure. However, some of the commonly used single-component working fluids have relatively poor properties and heat transfer performance. For example, water is the best coolant in terms of properties, yet in certain applications where the system operates at low temperature ambient, it cannot be implemented due to freezing risk. The common solution for this problem is to use the antifreeze mixtures (binary mixtures of water and alcohol) to reduce the freezing point. In such cases, utilizing binary mixtures to tune working fluid properties becomes an alternative approach. This study has two main objectives; (1) to experimentally investigate the two-phase spray cooling performance of water/2-propanol binary mixture, and (2) to numerically investigate the performance of an advanced heat spreader featuring high and directional thermal conductivity materials for high heat flux focal sources. The first part of the study involves experimental characterization of heat transfer performance. Tests are conducted on a small-scale, closed loop spray cooling system featuring a pressure atomized spray nozzle. The test section, made of copper, measures 10 mm x 10 mm x 2 mm

  8. Two dimensional impinging jet cooling of high heat flux surface in magnetic confinement fusion reactor

    SciTech Connect

    Inoue, A.; Tanno, T.; Takahashi, M.

    1994-12-31

    Divertor surface of a magnetic confinement fusion reactor is exposed to strong radiation heating by high flux charged particles. According to standard design of the ITER, the heat flux of the divertor surface becomes average 15MW/m{sup 2} or more. In this study, a cooling by a two dimensional impinging jet flow is proposed to cool such high heat flux surface. For an impinging jet flow to flat heated surface, such as CHF is obtained only in the limited surface region where the jet flow hits directly. Apart from the region, the CHF decreases abruptly with the distance from the center. The main reason is that the pressure decreases abruptly as apart from the center region and the liquid flow is spread away from the heated surface region by the strong boiling. To overcome these difficulties, the authors propose that the impinging jet is applied to the heat transfer wall with a concave surface, because the pressure change becomes mild by the centrifugal force along the curved surface. The increase of the radial pressure gradient in the vertical direction to the curved surface promotes the departure of vapor bubbles near the wall region. It is expected that this mechanism as well as keeping high pressure along the flow works to enhance the CHF. To obtain the high heat flux in the wide region, a use of a two-dimensional impinging jet is suitable instead of a round jet.

  9. A unique high heat flux facility for testing hypersonic engine components

    NASA Technical Reports Server (NTRS)

    Melis, Matthew E.; Gladden, Herbert J.

    1990-01-01

    This paper describes the Hot Gas Facility, a unique, reliable, and cost-effective high-heat-flux facility for testing hypersonic engine components developed at the NASA Lewis Research Center. The Hot Gas Facility is capable of providing heat fluxes ranging from 200 Btu/sq ft per sec on flat surfaces up to 8000 Btu/sq ft per sec at a leading edge stagnation point. The usefulness of the Hot Gas Facility for the NASP community was demonstrated by testing hydrogen-cooled structures over a range of temperatures and pressures. Ranges of the Reynolds numbers, Prandtl numbers, enthalpy, and heat fluxes similar to those expected during hypersonic flights were achieved.

  10. A unique high heat flux facility for testing hypersonic engine components

    NASA Technical Reports Server (NTRS)

    Melis, Matthew E.; Gladden, Herbert J.

    1990-01-01

    A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding high thermal loads expected during hypersonic flights. Consequently, there is a need for experimental facilities capable of providing a high heat flux environment for testing compound concepts and verifying analyses. A hydrogen/oxygen rocket engine was developed to provide a high enthalpy/high heat flux environment for component evaluation. This Hot Gas Facility is capable of providing heat fluxes ranging from 200 (on flat surfaces) up to 8000 Btu per sq ft per sec (at a leading edge stagnation point). Gas temperatures up to 5500 R can be attained as well as Reynolds numbers up to 360,000 per ft. Test articles such as cowl leading edges, transpiration-cooled seals, fuel injectors, and cooled panel concepts can be evaluated with gaseous hydrogen as coolant. This facility and its configuration and test capabilities are discussed. Results from flow characterization experiments are also shown and their implications considered.

  11. Failure analysis of beryllium tile assembles following high heat flux testing for the ITER program

    SciTech Connect

    B. C. Odegard, Jr.; C. H. Cadden; N. Y. C. Yang

    2000-05-01

    The following document describes the processing, testing and post-test analysis of two Be-Cu assemblies that have successfully met the heat load requirements for the first wall and dome sections for the ITER (International Thermonuclear Experimental Reactor) fusion reactor. Several different joint assemblies were evaluated in support of a manufacturing technology investigation aimed at diffusion bonding or brazing a beryllium armor tile to a copper alloy heat sink for fusion reactor applications. Judicious selection of materials and coatings for these assemblies was essential to eliminate or minimize interactions with the highly reactive beryllium armor material. A thin titanium layer was used as a diffusion barrier to isolate the copper heat sink from the beryllium armor. To reduce residual stresses produced by differences in the expansion coefficients between the beryllium and copper, a compliant layer of aluminum or aluminum-beryllium (AlBeMet-150) was used. Aluminum was chosen because it does not chemically react with, and exhibits limited volubility in, beryllium. Two bonding processes were used to produce the assemblies. The primary process was a diffusion bonding technique. In this case, undesirable metallurgical reactions were minimized by keeping the materials in a solid state throughout the fabrication cycle. The other process employed an aluminum-silicon layer as a brazing filler material. In both cases, a hot isostatic press (HIP) furnace was used in conjunction with vacuum-canned assemblies in order to minimize oxidation and provide sufficient pressure on the assemblies for full metal-to-metal contact and subsequent bonding. The two final assemblies were subjected to a suite of tests including: tensile tests and electron and optical metallography. Finally, high heat flux testing was conducted at the electron beam testing system (EBTS) at Sandia National Laboratories, New Mexico. Here, test mockups were fabricated and subjected to normal heat loads to

  12. Experimental Study of Thermal Crisis in Connection with Tokamak Reactor High Heat Flux Components

    SciTech Connect

    Gallo, D.; Giardina, M.; Castiglia, F.; Celata, G.P.; Mariani, A.; Zummo, G.; Cumo, M.

    2000-12-31

    The results of an experimental research on high heat flux thermal crisis in forced convective subcooled water flow, under operative conditions of interest to the thermal-hydraulic design of TOKAMAK fusion reactors, are here reported. These experiments, carried out in the framework of a collaboration between the Nuclear Engineering Department of Palermo University and the National Institute of Thermal - Fluid Dynamics of the ENEA - Casaccia (Rome), were performed on the STAF (Scambio Termico Alti Flussi) water loop and consisted, essentially, in a high speed photographic study which enabled focusing several information on bubble characteristics and flow patterns taking place during the burnout phenomenology.

  13. Electron heat flux instability

    NASA Astrophysics Data System (ADS)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Lazar, M.; Qureshi, M. N. S.

    2017-02-01

    The heat flux instability is an electromagnetic mode excited by a relative drift between the protons and two-component core-halo electrons. The most prominent application may be in association with the solar wind where drifting electron velocity distributions are observed. The heat flux instability is somewhat analogous to the electrostatic Buneman or ion-acoustic instability driven by the net drift between the protons and bulk electrons, except that the heat flux instability operates in magnetized plasmas and possesses transverse electromagnetic polarization. The heat flux instability is also distinct from the electrostatic counterpart in that it requires two electron species with relative drifts with each other. In the literature, the heat flux instability is often called the 'whistler' heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. This paper elucidates all of these fundamental plasma physical properties associated with the heat flux instability starting from a simple model, and gradually building up more complexity towards a solar wind-like distribution functions. It is found that the essential properties of the instability are already present in the cold counter-streaming electron model, and that the instability is absent if the protons are ignored. These instability characteristics are highly reminiscent of the electron firehose instability driven by excessive parallel temperature anisotropy, propagating in parallel direction with respect to the ambient magnetic field, except that the free energy source for the heat flux instability resides in the effective parallel pressure provided by the counter-streaming electrons.

  14. Thermal evaluation of uranium silicide miniplates irradiated at high heat flux

    SciTech Connect

    Donna P. Guillen

    2012-09-01

    The Gas Test Loop (GTL)-1 irradiation experiment was conducted in the Advanced Test Reactor (ATR) to assess corrosion performance of proposed booster fuel at heat flux levels ~30% above the design operating condition. Sixteen miniplates fabricated from 25% enriched, high-density (4.8 g U/cm3) U3Si2/Al dispersion fuel with 6061 aluminum cladding were subjected to peak beginning of cycle (BOC) heat fluxes ranging from 411 to 593 W/cm2. No adverse impacts to the miniplates were observed at these high heat flux levels. A detailed finite element model was constructed to calculate temperatures and heat flux for an as-run cycle average effective ATR south lobe power of 25.4 MW(t). Miniplate heat flux levels and fuel, cladding, hydroxide, and coolant–hydroxide interface temperatures were calculated using the average hydroxide thickness on each miniplate measured during post-irradiation examination. The purpose of this study was to obtain a best estimate of the as-run experiment temperatures to aid in establishing acceptable heat flux levels and designing fuel qualification experiments for this fuel type.

  15. Molecular dynamic simulation of tungsten ablation under transient high heat flux

    NASA Astrophysics Data System (ADS)

    Yan, Sha; Zhu, Yizhou; Xue, Jianming; Zhang, Jie; Qu, Miao; Le, Xiaoyun

    2015-08-01

    Molecular dynamic (MD) method is used to simulation the tungsten ablation under transient high heat flux generated by energetic ions. A model including 363,600 W atoms was built based on Finnis-Sinclair potential. The results show that the ablation threshold is much lower than the one of boiling. So the ablation effects might be underestimated if using energy threshold of boiling instead of that of ablation. Particle size distribution of ablation products follows a power decay law with an exponent around -2.5, which does not affect by the incident heat flux. The transverse velocities of particles obey normal distribution, and a stream speed is added to the random movement for the longitudinal velocity. As the ablation start up, the recoiled impulse can induce shock wave in remained target, which is supported by experimental pressure wave measurements.

  16. Nonlinear aspects of high heat flux nucleate boiling heat transfer. Part 2, Results

    SciTech Connect

    Sadasivan, P.; Unal, C.; Nelson, R.

    1994-04-01

    This paper describes the results of a study aimed at understanding nonlinear aspects of the macrolayer-controlled heat transfer process associated with high heat flux nucleate boiling and the critical heat flux. Simulations of realistic heater surfaces have been carried out by detailed microscopic modeling of the surfaces. Individual nucleation sites are allowed to activate or deactivate depending on the thermal conditions that prevail at the site. The results indicate that significant spatial and temporal temperature variations can occur on the surface, and that thermal interactions among sites can result in some sites operating extremely intermittently. Surface-averaged temperatures show highly nonlinear behavior. This suggests the possibility of the system exhibiting chaotic behavior under appropriate experimental conditions. It is proposed that such nonlinear behavior is one of the reasons why mechanistic predictive capabilities for the boiling process have remained elusive.

  17. Vapor shield protection of plasma facing components under incident high heat flux

    NASA Astrophysics Data System (ADS)

    Gilligan, J.; Bourham, M.; Hankins, O.; Eddy, W.; Hurley, J.; Black, D.

    1992-12-01

    Disruption damage to plasma facing components has been found to be a limiting design constraint in ITER and other large fusion devices. A growing data base is confirming the role of the vapor shield in protecting ablated surfaces under disruption-like conditions, which would imply longer lifetimes for plasma facing components. We present new results for exposure of various material surfaces to high heat fluxes up to 70 GW/m 2 over 100 μs (7 MJ/m 2) in the SIRENS high heat flux test facility. Tested materials are graphite grades, pyrolytic graphite, refractory metals and alloys, refractory coatings on copper substrates, boron nitride and preliminary results of diamond coating on silicon substrates. An empirical scaling law of the energy transmission factor through the vapor shield has been obtained. The application of a strong external magnetic field, to reduce turbulent energy transport in the vapor shield boundary, is shown to decrease f by as much as 35% for fields of 8 T.

  18. Response of materials to high heat fluxes during operation in fusion reactors

    SciTech Connect

    Hassanein, A.M.

    1988-07-01

    Very high energy deposition on first wall and other components of a fusion reactor is expected due to plasma instabilities during both normal and off-normal operating conditions. Off-normal operating conditions result from plasma disruptions where the plasma loses confinement and dumps its energy on the reactor components. High heat flux may also result from normal operating conditions due to fluctuations in plasma edge conditions. This high energy dump in a short time results in very high surface temperatures and may consequently cause melting and vaporization of these materials. The net erosion rates resulting from melting and vaporization are very important to estimate the lifetime of such components. The response of different candidate materials to this high heat fluxes is determined for different energy densities and deposition times. The analysis used a previously developed model to solve the heat conduction equation in two moving boundaries. One moving boundary is at the surface to account for surface recession due to vaporization and the second moving boundary is to account for the solid-liquid interface inside the material. The calculations are done parametrically for both the expected energy deposited and the deposition time. These ranges of energy and time are based on recent experimental observations in current fusion devices. The candidate materials analyzed are stainless steel, carbon, and tungsten. 8 refs., 9 figs.

  19. Manufacturing and High Heat Flux Testing of Brazed Flat-Type W/CuCrZr Plasma Facing Components

    NASA Astrophysics Data System (ADS)

    Lian, Youyun; Liu, Xiang; Feng, Fan; Chen, Lei; Cheng, Zhengkui; Wang, Jin; Chen, Jiming

    2016-02-01

    Water-cooled flat-type W/CuCrZr plasma facing components with an interlayer of oxygen-free copper (OFC) have been developed by using vacuum brazing route. The OFC layer for the accommodation of thermal stresses was cast onto the surface of W at a temperature range of 1150 °C-1200 °C in a vacuum furnace. The W/OFC cast tiles were vacuum brazed to a CuCrZr heat sink at 940 °C using the silver-free filler material CuMnSiCr. The microstructure, bonding strength, and high heat flux properties of the brazed W/CuCrZr joint samples were investigated. The W/Cu joint exhibits an average tensile strength of 134 MPa, which is about the same strength as pure annealed copper. High heat flux tests were performed in the electron beam facility EMS-60. Experimental results indicated that the brazed W/CuCrZr mock-up experienced screening tests of up to 15 MW/m2 and cyclic tests of 9 MW/m2 for 1000 cycles without visible damage. supported by National Natural Science Foundation of China (No. 11205049) and the National Magnetic Confinement Fusion Science Program of China (No. 2011GB110004)

  20. Neutron-irradiation effects on high heat flux components ? examination of plasma-facing materials and their joints

    NASA Astrophysics Data System (ADS)

    Rödig, M.; Conrad, R.; Derz, H.; Duwe, R.; Linke, J.; Lodato, A.; Merola, M.; Pott, G.; Vieider, G.; Wiechers, B.

    2000-12-01

    The neutron-irradiation experiments PARIDE 1 and PARIDE 2 have been performed at 350°C and 700°C with fluences of 0.35 dpa. The major part of the post-irradiation tests are high heat flux simulation experiments carried out in the electron beam facility JUDITH. These tests cover thermal fatigue experiments with small-scale high heat flux components, and on the other hand, thermal shock tests on the plasma-facing materials. Actively cooled samples were made from CFC, or beryllium as plasma-facing materials and copper alloys as heat sink materials. Different designs (flat tile, monoblock) and joining techniques (brazing, welding) were used. Best performance was found for CFC/Cu monoblock mock-ups, but also the brazed Be/Cu flat tile mock-ups fulfill the operational requirements for first wall components. Thermal shock experiments show a higher erosion after neutron irradiation. This degradation is either due to a reduced thermal conductivity (carbon) or to a decreased ductility after irradiation (beryllium).

  1. A low-frequency wave motion mechanism enables efficient energy transport in carbon nanotubes at high heat fluxes.

    PubMed

    Zhang, Xiaoliang; Hu, Ming; Poulikakos, Dimos

    2012-07-11

    The great majority of investigations of thermal transport in carbon nanotubes (CNTs) in the open literature focus on low heat fluxes, that is, in the regime of validity of the Fourier heat conduction law. In this paper, by performing nonequilibrium molecular dynamics simulations we investigated thermal transport in a single-walled CNT bridging two Si slabs under constant high heat flux. An anomalous wave-like kinetic energy profile was observed, and a previously unexplored, wave-dominated energy transport mechanism is identified for high heat fluxes in CNTs, originated from excited low frequency transverse acoustic waves. The transported energy, in terms of a one-dimensional low frequency mechanical wave, is quantified as a function of the total heat flux applied and is compared to the energy transported by traditional Fourier heat conduction. The results show that the low frequency wave actually overtakes traditional Fourier heat conduction and efficiently transports the energy at high heat flux. Our findings reveal an important new mechanism for high heat flux energy transport in low-dimensional nanostructures, such as one-dimensional (1-D) nanotubes and nanowires, which could be very relevant to high heat flux dissipation such as in micro/nanoelectronics applications.

  2. High heat flux accelerator targets cooling with liquid-metal jet impingement

    NASA Astrophysics Data System (ADS)

    Silverman, I.; Arenshtam, A.; Kijel, D.; Nagler, A.

    2005-12-01

    Accelerator targets for radioisotope production generate very high density of thermal energy in the target material, which absorbs the particles beam. The design of these targets requires efficient heat removal techniques in order to preserve the integrity of the target. Normal average heat fluxes from these targets are around 1 kW/cm2 and may reach order of magnitude higher values at hot spots. Few techniques exist to deal with such high heat fluxes. One of them is jet impingement that has been proved to be able to deal with heat fluxes as high as 40 kW/cm2 using water as coolant. However, this requires very high jet velocities of more than 100 m/s. A few theoretical and experimental studies indicate that liquid-metal coolants (e.g., gallium or gallium alloys) can improve the heat transfer efficiency in this configuration. Experimental cooling loops based on water and liquid-metal jet impingement have been designed and built at Soreq to evaluate this method. For the current liquid-metal system an eutectic alloy of gallium and indium (GaIn) is used. Initial experiments demonstrate that the GaIn cooling system can deal with heat flux of about 2 kW/cm2 over an area of 1 cm2. The jet velocity is less than 4 m/s and the required differential pressure from the pump is less than 1 bar.

  3. Diamond Microchannel Heat Sink Designs For High Heat Flux Thermal Control

    NASA Astrophysics Data System (ADS)

    Corbin, Michael V.; DeBenedictis, Matthew M.; James, David B.; LeBlanc, Stephen P.; Paradis, Leo R.

    2002-08-01

    Directed energy weapons, wide band gap semiconductor based radars, and other powerful systems present significant thermal control challenges to component designers. heat Flux levels approaching 2000 W/cm(2) are encountered at the base of laser diodes, and levels as high as 500 WI /cm(2) are expected in laser slabs and power amplifier tube collectors. These impressive heat flux levels frequently combine with strict operating temperature requirements to further compound the thermal control problem. Many investigators have suggested the use of diamond heat spreaders to reduce flux levels at or near to its source, and some have suggested that diamond microchannel heat sinks ultimately may play a significant role in the solution of these problems. Design engineers at Raytheon Company have investigated the application of all-diamond microchannel heat sinks to representative high heat flux problems and have found the approach promising. Diamond microchannel fabrication feasibility has been demonstrated; integration into packaging systems and the accompanying material compatibility issues have been addressed; and thermal and hydrodynamic performance predictions have been made for selected, possible applications. An example of a practical, all diamond microchannel heat sink has been fabricated, and another is in process and will be performance tested. The heat sink assembly is made entirely of optical quality, CVD diamond and is of sufficient strength to withstand the thermal and pressure-induced mechanical loads associated with manufacture and use in tactical weapons environment. The work presented describes the development program's accomplishments to date, and highlights many of the areas for future study.

  4. Application of amorphous filler metals in production of fusion reactor high heat flux components

    SciTech Connect

    Kalin, B.A.; Fedotov, V.T.; Grigoriev, A.E.

    1994-12-31

    The technology of Al-Si, Zr-Ti-Be and Ti-Zr-Cu-Ni amorphous filler metals for Be and graphite brazing with Cu, Mo and V was developed. The fusion reactor high heat flux components from Cu-Be, Cu-graphite, Mo-Be, Mo-graphite, V-Re and V-graphite materials were produced by brazing. Every component represents metallic base, to which Be or graphite plates are brazed. The distance between plates was equal 0.2 times the plate height. These components were irradiated by hydrogen plasma with 5 x 10{sup 6} W/m{sup 2} power. The microstructure and the element distribution in the brazed zone were investigated before and after heat plasma irradiation. Topography graphite plate surfaces and topography of metal surfaces between plates were also investigated after heat plasma irradiation. The results of microstructure investigation and material erosion are discussed.

  5. Calibration of high-heat-flux sensors in a solar furnace

    NASA Astrophysics Data System (ADS)

    Ballestrín, J.; Rodríguez-Alonso, M.; Rodríguez, J.; Cañadas, I.; Barbero, F. J.; Langley, L. W.; Barnes, A.

    2006-12-01

    The most common sensors used for the measurement of high solar irradiance are the Gardon gauges, which are usually calibrated using a black body at a certain temperature as the radiant source. This calibration procedure is assumed to produce a systematic error when solar irradiance measurements are taken using these sensors. This paper demonstrates a calorimetric method for calibrating these high-heat-flux gauges in a solar furnace. This procedure has enabled these sensors to be calibrated under concentrated solar radiation at higher irradiances under non-laboratory conditions in the CIEMAT solar furnace at the Plataforma Solar de Almería. Working at higher irradiances has allowed the uncertainty in the calibration constant of these sensors to be reduced. This work experimentally confirms the predicted systematic errors committed when measuring high solar irradiances using Gardon sensors calibrated with a black body.

  6. A framework for critical heat flux prediction in high heat flux, high subcooling components

    SciTech Connect

    Hechanova, A.E.; Kazimi, M.S.; Meyer, J.E.

    1995-12-31

    The critical heat flux (CHF) limits relevant to the design of plasma facing components in tokamak fusion reactors are considered. Highly subcooled water in unobstructed pipe flow are investigated using experiments and computational models. The experiments employ water flowing through a 9.5 mm bore in a 19 mm x 19 mm copper monoblock. Single-sized heating of the block is achieved by passing an electric current through a 51 mm long plasma sprayed thin layer (0.4 mm) of tungsten overlaying a thin film (0.1 mm) of plasma sprayed ceramic on an outer wall. In the analysis, the heat transfer coefficient on the coolant-side wall relies on extrapolation of existing nucleate boiling correlations but is validated using outer wall temperature measurements and a heat conduction model. The experimental results are combined with a CHF data base from several sources to enhance the generality of the proposed CHF correlation. The CHF data base parameter ranges are as follows: Peclet numbers between 7 {times}10{sup 4} to 3.2 {times} 10{sup 6}, coolant channel diameter between 5 and 25 mm, pressure between 1 and 7 MPa, and equilibrium quality between {minus}0.49 and {minus}0.07. The proposed correlation bounds the CHF data base as a lower limit and, thus, is an appropriate conservative limit for design applications.

  7. Experimental and analytical studies of high heat flux components for fusion experimental reactor

    NASA Astrophysics Data System (ADS)

    Araki, Masanori

    1993-03-01

    In this report, the experimental and analytical results concerning the development of plasma facing components of ITER are described. With respect to developing high heat removal structures for the divertor plates, an externally-finned swirl tube was developed based on the results of critical heat flux (CHF) experiments on various tube structures. As the result, the burnout heat flux, which also indicates incident CHF, of 41 (+/-) 1 MW/sq m was achieved in the externally-finned swirl tube. The applicability of existing CHF correlations based on uniform heating conditions was evaluated by comparing the CHF experimental data with the smooth and the externally-finned tubes under one-sided heating condition. As the results, experimentally determined CHF data for straight tube show good agreement, for the externally-finned tube, no existing correlations are available for prediction of the CHF. With respect to the evaluation of the bonds between carbon-based material and heat sink metal, results of brazing tests were compared with the analytical results by three dimensional model with temperature-dependent thermal and mechanical properties. Analytical results showed that residual stresses from brazing can be estimated by the analytical three directional stress values instead of the equivalent stress value applied. In the analytical study on the separatrix sweeping for effectively reducing surface heat fluxes on the divertor plate, thermal response of the divertor plate was analyzed under ITER relevant heat flux conditions and has been tested. As the result, it has been demonstrated that application of the sweeping technique is very effective for improvement in the power handling capability of the divertor plate and that the divertor mock-up has withstood a large number of additional cyclic heat loads.

  8. Development of Advanced Thermal and Environmental Barrier Coatings Using a High-Heat-Flux Testing Approach

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2003-01-01

    The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 1700 C) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, high temperature capability thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity, which initially rises under the steady-state high temperature thermal gradient test due to coating sintering, and later drops under the cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on damage accumulation and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The external radiation resistance of the coating is assessed based on the measured specimen temperature response under a laser- heated intense radiation-flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature may be derived.

  9. Scrape-off layer modeling of radiative divertor and high heat flux experiments on DIII-D

    NASA Astrophysics Data System (ADS)

    Campbell, R. B.; Petrie, T. W.; Hill, D. N.

    1992-12-01

    We use a new multispecies 1D fluid code, NEWT-ID, to model DIII-D scrape-off layer (SOL) behavior during radiative divertor and high heat flux experiments. The separatrix location and the width of the SOL are uncertain, and affect the comparison of the data in important ways. The model agrees with many of the experimental measurements for a particular prescription for the separatrix location. The model cannot explain the recent data on the separatrix Ti with a conventional picture of ion and electron power flows across the separatrix. Radial transport of particles and heat in some form is required to explain the peak heat flux data before and after gas puffing. For argon puffing in the private flux region, entrainment is poor in the steady state. The calculations suggest that strike point argon puffing in a slot divertor geometry results in substantially better entrainment. Self-consistent, steady-state solutions with radiated powers up to 80% of the SOL power input are obtained in 1D. We discuss significant radial effects which warrant the development of a code which can treat strongly radiating impurities in 2D geometries.

  10. Scrape-off layer modeling of radiative divertor and high heat flux experiments on D3-D

    NASA Astrophysics Data System (ADS)

    Campbell, R. B.; Petrie, T. W.; Hill, D. N.

    1992-03-01

    We use a new multispecies 1-D fluid code, NEWT-1D, to model DIII-D scrape-off layer (SOL) behavior during radiative divertor and high heat flux experiments. The separatrix location and the width of the SOL are uncertain, and affect the comparison of the data in important ways. The model agrees with many of the experimental measurements for a particular prescription for the separatrix location. The model cannot explain the recent data on the separatrix T(sub i) with a conventional picture of ion and electron power flows across the separatrix. Radial transport of particles and heat in some form is required to explain the peak heat flux data before and after gas puffing. For argon puffing in the private flux region, entrainment is poor in the steady state. The calculations suggest that strike point argon puffing in a slot divertor geometry results in substantially better entrainment. Self-consistent, steady-state solutions with radiated powers up to 80 percent of the SOL power input are obtained in 1-D. We discuss significant radial effects which warrant the development of a code which can treat strongly radiating impurities in 2-D geometries.

  11. Prototyping phase of the high heat flux scraper element of Wendelstein 7-X

    DOE PAGES

    Boscary, Jean; Greuner, Henri; Ehrke, G.; ...

    2016-03-24

    The water-cooled high heat flux scraper element aims to reduce excessive heat loads on the target element ends of the actively cooled divertor of Wendelstein 7-X. Its purpose is to intercept some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper element has 24 identical plasma facing components (PFCs) divided into 6 modules. One module has 4 PFCs hydraulically connected in series by 2 water boxes. A PFC, 247 mm long and 28 mm wide, has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equippedmore » with a copper twisted tape. 4 full-scale prototypes of PFCs have been successfully tested in the GLADIS facility up to 20 MW/m2. The difference observed between measured and calculated surface temperatures is probably due to the inhomogeneity of CFC properties. The design of the water box prototypes has been detailed to allow the junction between the cooling pipe of the PFCs and the water boxes by internal orbital welding. In conclusion, the prototypes are presently under fabrication.« less

  12. Prototyping phase of the high heat flux scraper element of Wendelstein 7-X

    SciTech Connect

    Boscary, Jean; Greuner, Henri; Ehrke, G.; Boswirth, Bernd; Wang, Zhongwei; Clark, Emily; Lumsdaine, A.; Tretter, Jorg; McGinnis, D.; Lore, Jeremy D.; Ekici, K.

    2016-03-24

    The water-cooled high heat flux scraper element aims to reduce excessive heat loads on the target element ends of the actively cooled divertor of Wendelstein 7-X. Its purpose is to intercept some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper element has 24 identical plasma facing components (PFCs) divided into 6 modules. One module has 4 PFCs hydraulically connected in series by 2 water boxes. A PFC, 247 mm long and 28 mm wide, has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equipped with a copper twisted tape. 4 full-scale prototypes of PFCs have been successfully tested in the GLADIS facility up to 20 MW/m2. The difference observed between measured and calculated surface temperatures is probably due to the inhomogeneity of CFC properties. The design of the water box prototypes has been detailed to allow the junction between the cooling pipe of the PFCs and the water boxes by internal orbital welding. In conclusion, the prototypes are presently under fabrication.

  13. ANL ITER high-heat-flux blanket-module heat transfer experiments. Fusion Power Program

    SciTech Connect

    Kasza, K.E.

    1992-02-01

    An Argonne National Laboratory facility for conducting tests on multilayered slab models of fusion blanket designs is being developed; some of its features are described. This facility will allow testing under prototypic high heat fluxes, high temperatures, thermal gradients, and variable mechanical loadings in a helium gas environment. Steady and transient heat flux tests are possible. Electrical heating by a two-sided, thin stainless steel (SS) plate electrical resistance heater and SS water-cooled cold panels placed symmetrically on both sides of the heater allow achievement of global one-dimensional heat transfer across blanket specimen layers sandwiched between the hot and cold plates. The heat transfer characteristics at interfaces, as well as macroscale and microscale thermomechanical interactions between layers, can be studied in support of the ITER engineering design effort. The engineering design of the test apparatus has shown that it is important to use multidimensional thermomechanical analysis of sandwich-type composites to adequately analyze heat transfer. This fact will also be true for the engineering design of ITER.

  14. ANL ITER high-heat-flux blanket-module heat transfer experiments

    SciTech Connect

    Kasza, K.E.

    1992-02-01

    An Argonne National Laboratory facility for conducting tests on multilayered slab models of fusion blanket designs is being developed; some of its features are described. This facility will allow testing under prototypic high heat fluxes, high temperatures, thermal gradients, and variable mechanical loadings in a helium gas environment. Steady and transient heat flux tests are possible. Electrical heating by a two-sided, thin stainless steel (SS) plate electrical resistance heater and SS water-cooled cold panels placed symmetrically on both sides of the heater allow achievement of global one-dimensional heat transfer across blanket specimen layers sandwiched between the hot and cold plates. The heat transfer characteristics at interfaces, as well as macroscale and microscale thermomechanical interactions between layers, can be studied in support of the ITER engineering design effort. The engineering design of the test apparatus has shown that it is important to use multidimensional thermomechanical analysis of sandwich-type composites to adequately analyze heat transfer. This fact will also be true for the engineering design of ITER.

  15. Approaching the limits of two-phase boiling heat transfer: High heat flux and low superheat

    NASA Astrophysics Data System (ADS)

    Palko, J. W.; Zhang, C.; Wilbur, J. D.; Dusseault, T. J.; Asheghi, M.; Goodson, K. E.; Santiago, J. G.

    2015-12-01

    We demonstrate capillary fed porous copper structures capable of dissipating over 1200 W cm-2 in boiling with water as the working fluid. Demonstrated superheats for this structure are dramatically lower than those previously reported at these high heat fluxes and are extremely insensitive to heat input. We show superheats of less than 10 K at maximum dissipation and varying less than 5 K over input heat flux ranges of 1000 W cm-2. Fabrication of the porous copper layers using electrodeposition around a sacrificial template allows fine control of both microstructure and bulk geometry, producing structures less than 40 μm thick with active region lateral dimensions of 2 mm × 0.3 mm. The active region is volumetrically Joule heated by passing an electric current through the porous copper bulk material. We analyze the heat transfer performance of the structures and suggest a strong influence of pore size on superheat. We compare performance of the current structure to existing wick structures.

  16. Oxidation and Volatilization from Tungsten Brush High Heat Flux Armor During High Temperature Steam Exposure

    SciTech Connect

    Smolik, Galen Richard; Pawelko, Robert James; Anderl, Robert Andrew; Petti, David Andrew

    2000-05-01

    Tungsten brush accommodates thermal stresses and high heat flux in fusion reactor components such as plasma facing surfaces or armor. However, inherently higher surface areas are introduced with the brush design. We have tested a specific design of tungsten brush in steam between 500 and 1100°C. Hydrogen generation and tungsten volatilization rates were determined to address fusion safety issues. The brush prepared from 3.2-mm diameter welding rods had a packing density of 85 percent. We found that both hydrogen generation and tungsten volatilization from brush, fixtured to represent a unit within a larger component, were less than projections based upon the total integrated surface area (TSA). Steam access and the escape of hydrogen and volatile oxide from void spaces within the brush are restricted compared to specimens with more direct diffusion pathways to the test environment. Hydrogen generation rates from restrained specimens based on normal surface area (NSA) remain about five times higher than rates based on total surface areas from specimens with direct steam access. Volatilization rates from restrained specimens based upon normal surface area (NSA) were only 50 percent higher than our historic cumulative maximum flux plot (CMFP) for tungsten. This study has shown that hydrogen generation and tungsten volatilization from brush do not scale according to predictions with previously determined rates, but in fact, with higher packing density could approach those from flat surfaces.

  17. Comparison of the high temperature heat flux sensor to traditional heat flux gages under high heat flux conditions.

    SciTech Connect

    Blanchat, Thomas K.; Hanks, Charles R.

    2013-04-01

    Four types of heat flux gages (Gardon, Schmidt-Boelter, Directional Flame Temperature, and High Temperature Heat Flux Sensor) were assessed and compared under flux conditions ranging between 100-1000 kW/m2, such as those seen in hydrocarbon fire or propellant fire conditions. Short duration step and pulse boundary conditions were imposed using a six-panel cylindrical array of high-temperature tungsten lamps. Overall, agreement between all gages was acceptable for the pulse tests and also for the step tests. However, repeated tests with the HTHFS with relatively long durations at temperatures approaching 1000ÀC showed a substantial decrease (10-25%) in heat flux subsequent to the initial test, likely due to the mounting technique. New HTHFS gages have been ordered to allow additional tests to determine the cause of the flux reduction.

  18. Manufacturing and thermomechanical testing of actively cooled all beryllium high heat flux test pieces

    SciTech Connect

    Vasiliev, N.N.; Sokolov, Yu.A.; Shatalov, G.E.

    1995-09-01

    One of the problems affiliated to ITER high heat flux elements development is a problem of interface of beryllium protection with heat sink routinely made of copper alloys. To get rid of this problem all beryllium elements could be used as heat receivers in places of enhanced thermal loads. In accordance with this objectives four beryllium test pieces of two types have been manufactured in {open_quotes}Institute of Beryllium{close_quotes} for succeeding thermomechanical testing. Two of them were manufactured in accordance with JET team design; they are round {open_quotes}hypervapotron type{close_quotes} test pieces. Another two ones are rectangular test sections with a twisted tape installed inside of the circular channel. Preliminary stress-strain analysis have been performed for both type of the test pieces. Hypervapotrons have been shipped to JET where they were tested on JET test bed. Thermomechanical testing of pieces of the type of {open_quotes}swirl tape inside of tube{close_quotes} have been performed on Kurchatov Institute test bed. Chosen beryllium grade properties, some details of manufacturing, results of preliminary stress-strain analysis and thermomechanical testing of the test pieces {open_quotes}swirl tape inside of tube{close_quotes} type are given in this report.

  19. High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

    SciTech Connect

    C.H. Skinner; C.A. Gentile; A. Hassanein

    2002-01-28

    A new technique for studying high heat flux interactions with plasma facing components is presented. The beam from a continuous wave 300 W neodymium laser was focused to 80 W/mm2 and scanned at high speed over the surface of carbon tiles. These tiles were previously used in the TFTR [Tokamak Fusion Test Reactor] inner limiter and have a surface layer of amorphous hydrogenated carbon that was codeposited during plasma operations. Laser scanning released up to 84% of the codeposited tritium. The temperature rise of the codeposit on the tiles was significantly higher than that of the manufactured material. In one experiment, the codeposit surface temperature rose to 1,770 C while for the same conditions, the manufactured surface increased to only 1,080 C. The peak temperature did not follow the usual square-root dependence on heat pulse duration. Durations of order 100 ms resulted in brittle destruction and material loss from the surface, while a duration of approximately 10 ms showed minimal change. A digital microscope imaged the codeposit before, during, and after the interaction with the laser and revealed hot spots on a 100-micron scale. These results will be compared to analytic modeling and are relevant to the response of plasma facing components to disruptions and vertical displacement events (VDEs) in next-step magnetic fusion devices.

  20. Microsample Characterization of Coatings for Grcop-84 for High Heat Flux Applications

    NASA Technical Reports Server (NTRS)

    Hemker, Kevin

    2003-01-01

    A multidisciplinary Johns Hopkins University-NASA Glenn team is undertaking a collaborative research program to elucidate and model the thermal stability and mechanical integrity of candidate coatings for GRCop-84. GRCop-84 is a high conductivity, high strength copper alloy that was recently developed at NASA Glenn for use in high temperature, high heat flux applications. With potential applications in rocket motor combustion chamber liners, nozzle ramps and other actively cooled structures, this new material offers great potential for decreasing weight and increasing reliability of third generation reusable launch vehicles. Current emphasis has turned toward the development of environmentally resistant and thermal barrier coatings for this alloy. Metallic coatings such as NiCrAlY and Cu-8-30%Cr have shown promise in: prohibiting blanching, reducing dog-house failures, increasing operating temperatures and decreasing cooling requirements. The focus of this research program is to develop a fundamental understanding of the substrate-coating interactions that occur during thermal cycling (inter-diffusion, viscoplasticity, morphological evolution, crack formation, etc.) and to derive a science-based protocol for future coating selection, optimization and reliability assurance. The microsample tensile testing approach adopted for this study allows us to characterize small-scale and highly scale-specific coatings and properties in a way not possible by conventional means. In addition to providing much needed design data, the integration of microsample testing with detailed microstructural observations provides a mechanistic foundation for coating optimization and life prediction modeling.

  1. Local structure of cobalt nanoparticles synthesized by high heat flux plasma process

    NASA Astrophysics Data System (ADS)

    Orpe, P. B.; Paris, E.; Balasubramanian, C.; Joseph, B.; Mukherjee, S.; Di Gioacchino, D.; Marcelli, A.; Saini, N. L.

    2017-08-01

    We have used high heat flux plasma synthesis process to grow Co those for the morphology, stoichiometry and the local structure as a function of plasma current. We find that the nanoparticles produced by the thermal plasma method have different shapes and size distribution with the plasma current being a key parameter in controlling the formation of composition, morphology and crystalline structure. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements at Co K-edge have revealed formation of metal and metal oxide nanoparticles with the composition mainly depending on the arc current. While low plasma current appears to produce nanoparticles solely of CoO with a small amount of Co metal, the high plasma current tends to produce nanoparticles of CoO and Co3O4 oxides with increased amount of Co metal. The results are consistent with the morphological and structural analysis, showing nanoparticles of different shapes and size depending on the arc current.

  2. Hypersonic Engine Leading Edge Experiments in a High Heat Flux, Supersonic Flow Environment

    NASA Technical Reports Server (NTRS)

    Gladden, Herbert J.; Melis, Matthew E.

    1994-01-01

    A major concern in advancing the state-of-the-art technologies for hypersonic vehicles is the development of an aeropropulsion system capable of withstanding the sustained high thermal loads expected during hypersonic flight. Three aerothermal load related concerns are the boundary layer transition from laminar to turbulent flow, articulating panel seals in high temperature environments, and strut (or cowl) leading edges with shock-on-shock interactions. A multidisciplinary approach is required to address these technical concerns. A hydrogen/oxygen rocket engine heat source has been developed at the NASA Lewis Research Center as one element in a series of facilities at national laboratories designed to experimentally evaluate the heat transfer and structural response of the strut (or cowl) leading edge. A recent experimental program conducted in this facility is discussed and related to cooling technology capability. The specific objective of the experiment discussed is to evaluate the erosion and oxidation characteristics of a coating on a cowl leading edge (or strut leading edge) in a supersonic, high heat flux environment. Heat transfer analyses of a similar leading edge concept cooled with gaseous hydrogen is included to demonstrate the complexity of the problem resulting from plastic deformation of the structures. Macro-photographic data from a coated leading edge model show progressive degradation over several thermal cycles at aerothermal conditions representative of high Mach number flight.

  3. Microsample Characterization of Coatings for GRCop-84 for High Temperature High Heat Flux Application

    NASA Technical Reports Server (NTRS)

    Jain, Piyush; Hemker, Kevin J.; Raj, Sai V.

    2004-01-01

    NASA's Glenn Research Center has developed GRCop-84 (Cu-8at.%Cr-4% Nb), a high conductivity, high strength copper alloy for use as liners in rocket engine combustion chambers, nozzle ramps and other actively-cooled components subject to high heat fluxes. Two metallic coatings, NiCrAlY and Cu-26%Cr, are being considered for preventing blanching, reducing 'dog- house' failures and providing better environmental resistance to the GRCop-84 liners. This presentation will outline a study of coating-substrate interactions that occur as a result of thermal cycling and coating specific properties at different temperatures. A furnace has been built to thermally cycle the samples under argon. The microsample testing approach is being used to measure the coating-substrate interfacial strength. Cu-26Cr/GRCop-84 samples did not show any obvious interdiffusion after 300 thermal cycles. Interfacial strength tests of these samples were affected by porosity present in the samples. A complete set of observations and results for Cu-26Cr and NiCrAlY coatings will be presented.

  4. Development of advanced high heat flux and plasma-facing materials

    NASA Astrophysics Data System (ADS)

    Linsmeier, Ch.; Rieth, M.; Aktaa, J.; Chikada, T.; Hoffmann, A.; Hoffmann, J.; Houben, A.; Kurishita, H.; Jin, X.; Li, M.; Litnovsky, A.; Matsuo, S.; von Müller, A.; Nikolic, V.; Palacios, T.; Pippan, R.; Qu, D.; Reiser, J.; Riesch, J.; Shikama, T.; Stieglitz, R.; Weber, T.; Wurster, S.; You, J.-H.; Zhou, Z.

    2017-09-01

    Plasma-facing materials and components in a fusion reactor are the interface between the plasma and the material part. The operational conditions in this environment are probably the most challenging parameters for any material: high power loads and large particle and neutron fluxes are simultaneously impinging at their surfaces. To realize fusion in a tokamak or stellarator reactor, given the proven geometries and technological solutions, requires an improvement of the thermo-mechanical capabilities of currently available materials. In its first part this article describes the requirements and needs for new, advanced materials for the plasma-facing components. Starting points are capabilities and limitations of tungsten-based alloys and structurally stabilized materials. Furthermore, material requirements from the fusion-specific loading scenarios of a divertor in a water-cooled configuration are described, defining directions for the material development. Finally, safety requirements for a fusion reactor with its specific accident scenarios and their potential environmental impact lead to the definition of inherently passive materials, avoiding release of radioactive material through intrinsic material properties. The second part of this article demonstrates current material development lines answering the fusion-specific requirements for high heat flux materials. New composite materials, in particular fiber-reinforced and laminated structures, as well as mechanically alloyed tungsten materials, allow the extension of the thermo-mechanical operation space towards regions of extreme steady-state and transient loads. Self-passivating tungsten alloys, demonstrating favorable tungsten-like plasma-wall interaction behavior under normal operation conditions, are an intrinsic solution to otherwise catastrophic consequences of loss-of-coolant and air ingress events in a fusion reactor. Permeation barrier layers avoid the escape of tritium into structural and cooling

  5. Thermal Cyclic Behavior of Thermal and Environmental Barrier Coatings Investigated Under High-Heat-Flux Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2002-01-01

    Environmental barrier coatings (EBC's) have been developed to protect silicon-carbide- (SiC) based ceramic components in gas turbine engines from high-temperature environmental attack. With continuously increasing demands for significantly higher engine operating temperature, future EBC systems must be designed for both thermal and environmental protection of the engine components in combustion gases. In particular, the thermal barrier functions of EBC's become a necessity for reducing the engine-component thermal loads and chemical reaction rates, thus maintaining the required mechanical properties and durability of these components. Advances in the development of thermal and environmental barrier coatings (TBC's and EBC's, respectively) will directly impact the successful use of ceramic components in advanced engines. To develop high-performance coating systems, researchers must establish advanced test approaches. In this study, a laser high-heat-flux technique was employed to investigate the thermal cyclic behavior of TBC's and EBC's on SiC-reinforced SiC ceramic matrix composite substrates (SiC/SiC) under high thermal gradient and thermal cycling conditions. Because the laser heat flux test approach can monitor the coating's real-time thermal conductivity variations at high temperature, the coating thermal insulation performance, sintering, and delamination can all be obtained during thermal cycling tests. Plasma-sprayed yttria-stabilized zirconia (ZrO2-8 wt% Y2O3) thermal barrier and barium strontium aluminosilicate-based environmental barrier coatings (BSAS/BSAS+mullite/Si) on SiC/SiC ceramic matrix composites were investigated in this study. These coatings were laser tested in air under thermal gradients (the surface and interface temperatures were approximately 1482 and 1300 C, respectively). Some coating specimens were also subject to alternating furnace cycling (in a 90-percent water vapor environment at 1300 C) and laser thermal gradient cycling tests

  6. Thermal Conductivity and Elastic Modulus Evolution of Thermal Barrier Coatings under High Heat Flux Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may he encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1. 15 W/m-K, 1. 19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990C, 1100C, and 1320C. respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications.

  7. US-Japan workshop Q-181 on high heat flux components and plasma-surface interactions for next devices: Proceedings

    SciTech Connect

    McGrath, R.T.; Yamashina, T.

    1994-04-01

    This report contain viewgraphs of papers from the following sessions: plasma facing components issues for future machines; recent PMI results from several tokamaks; high heat flux technology; plasma facing components design and applications; plasma facing component materials and irradiation damage; boundary layer plasma; plasma disruptions; conditioning and tritium; and erosion/redeposition.

  8. Development of a high-heat-flux target for multimegawatt, multisecond neutral beams at ORNL

    SciTech Connect

    Combs, S.K.; Milora, S.L.; Bush, C.E.; Foster, C.A.; Haselton, H.H.; Hayes, P.H.; Menon, M.M.; Moeller, J.A.; Sluss, F.; Tsai, C.C.

    1984-01-01

    A high-heat-flux target has been developed for intercepting multimegawatt, multisecond neutral beam power at the Oak Ridge National Laboratory (ORNL). Water-cooled copper swirl tubes are used for the heat transfer medium; these tubes exhibit an enhancement in burnout heat flux over conventional axial-flow tubes. The target consists of 126 swirl tubes (each 0.95 cm in outside diameter with 0.16-cm-thick walls and approx. =1 m long) arranged in a V-shape. Two arrays of parallel tubes inclined at an angle ..cap alpha.. to the beam axis form the V-shape, and this geometry reduces the surface heat flux by a factor of 1/sin ..cap alpha.. (for the present design, ..cap alpha.. =13/sup 0/ and 21/sup 0/). In tests with the ORNL long-pulse ion source (13- by 43-cm grid), the target has handled up to 3-MW, 30-s beam pulses with no deleterious effects. The peak power density was estimated at approx. =15 kW/cm/sup 2/ normal to the beam axis (5.4 kW/cm/sup 2/ maximum on tube surfaces). The water flow rate through the target was 41.6 L/s (660 gpm) or 0.33 L/s (5.2 gpm) per tube (axial flow velocity = 11.6 m/s). The corresponding pressure drop across the target was 1.14 MPa (165 psi) with an inlet pressure of 1.45 MPa (210 psia). Data are also presented from backup experiments in which individual tubes were heated by a small ion source (10-cm-diam grid) to characterize tube performance. These results suggest that the target should handle peak power densities in the range 25 to 30 kW/cm/sup 2/ normal to the beam axis (approx. =10 kW/cm/sup 2/ maximum on tube surfaces) with the present flow parameters. This translates to beam power levels of 5 to 6 MW for equivalent beam optics.

  9. Evaluation of cooling concepts and specimen geometries for high heat flux tests on neutron irradiated divertor elements

    SciTech Connect

    Linke, J.; Bolt. H.; Breitbach, G.

    1994-12-31

    To assess the lifetime and the long term heat removal capabilities of plasma facing components in future thermonuclear fusion reactors such as ITER, neutron irradiation and subsequent high heat flux tests will be most essential. The effect of neutron damage will be simulated in material test reactors (such as the HFR-Petten) in a fission neutron environment. To investigate the heat loads during normal and off-normal operation scenarios a 60 kW electron beam test stand (Juelich Divertor Test Facility in Hot Cells, JUDITH) has been installed in a hot cell which can be operated by remote handling techniques. In this facility inertially cooled test coupons can be handled as well as small actively cooled divertor mock-ups. A special clamping mechanism for small test coupons (25 mm x 25 mm x 35 mm) with an integrated coolant channel within a copper or TZM heat sink has been developed and tested in an electron beam test bed. This method is an attractive alternative to costly large scale tests on complete divertor modules. The temperature and stress fields in individual CFC or beryllium tiles brazed to metallic heat sink (e.g. copper or TZM) can be investigated before and after neutron irradiation with moderate efforts.

  10. Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and

  11. High heat flux testing of divertor plasma facing materials and components using the HHF test facility at IPR

    NASA Astrophysics Data System (ADS)

    Patil, Yashashri; Khirwadkar, S. S.; Belsare, Sunil; Swamy, Rajamannar; Tripathi, Sudhir; Bhope, Kedar; Kanpara, Shailesh

    2016-02-01

    The High Heat Flux Test Facility (HHFTF) was designed and established recently at Institute for Plasma Research (IPR) in India for testing heat removal capability and operational life time of plasma facing materials and components of the ITER-like tokamak. The HHFTF is equipped with various diagnostics such as IR cameras and IR-pyrometers for surface temperature measurements, coolant water calorimetry for absorbed power measurements and thermocouples for bulk temperature measurements. The HHFTF is capable of simulating steady state heat load of several MW m-2 as well as short transient heat loads of MJ m-2. This paper presents the current status of the HHFTF at IPR and high heat flux tests performed on the curved tungsten monoblock type of test mock-ups as well as transient heat flux tests carried out on pure tungsten materials using the HHFTF. Curved tungsten monoblock type of test mock-ups were fabricated using hot radial pressing (HRP) technique. Two curved tungsten monoblock type test mock-ups successfully sustained absorbed heat flux up to 14 MW m-2 with thermal cycles of 30 s ON and 30 s OFF duration. Transient high heat flux tests or thermal shock tests were carried out on pure tungsten hot-rolled plate material (Make:PLANSEE) with incident power density of 0.49 GW m-2 for 20 milliseconds ON and 1000 milliseconds OFF time. A total of 6000 thermal shock cycles were completed on pure tungsten material. Experimental results were compared with mathematical simulations carried out using COMSOL Multiphysics for transient high heat flux tests.

  12. Magnetic fusion energy plasma interactive and high heat flux components. Volume III. Strategy for international collaborations in the areas of plasma materials interactions and high heat flux materials and components development

    SciTech Connect

    Gauster, W.B.; Bauer, W.; Roberto, J.B.; Post, D.E.

    1984-01-01

    The purpose of this summary is to assess opportunities for such collaborations in the specific areas of Plasma Materials Interaction and High Heat Flux Materials and Components Development, and to aid in developing a strategy to take advantage of them. After some general discussion of international collaborations, we summarize key technical issues and the US programs to address them. Then follows a summary of present collaborations and potential opportunities in foreign laboratories.

  13. Proceedings of US/Japan workshop, Q219 on high heat flux components and plasma surface interactions for next fusion devices

    SciTech Connect

    Ulrickson, M.A.; Stevens, P.L.; Hino, T.; Hirohata, Y.

    1996-12-01

    This report contains the viewgraphs from the proceedings of US/Japan Workshop on High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices. Some of the general topics covered by this report are: PFC/PSI in tokamak and helical devices; development of high heat flux components; PSIS and plasma facing materials;tritium; and material damage.

  14. Particulate generation during disruption simulation on the SIRENS high heat flux facility

    NASA Astrophysics Data System (ADS)

    Sharpe, John Phillip

    2000-12-01

    Successful implementation of advanced electrical power generation technology into the global marketplace requires at least two fundamental ideals: cost effectiveness and the guarantee of public safety. One general area of concern for fusion devices is the production of particulate, often referred to as dust or aerosol, from material exposed to high energy density fusion plasma. This dust may be radiologically activated and/or chemically toxic, and, if released to the environment, could become a hazard to the public. The goal of this investigation was to provide insight into the production and transport of particulate generated during the event of extreme heat loads to surfaces directly exposed to high energy density plasma. A step towards achieving this goal was an experiment campaign carried out with the S&barbelow;urface I&barbelow;nteṞaction E&barbelow;xperiment at Ṉorth Carolina S&barbelow;tate (SIRENS), a facility used for high heat flux experiments. These experiments involved exposing various materials, including copper, stainless steel 316, tungsten, aluminum, graphite (carbon), and mixtures of carbon and metals, to the high energy density plasma of the SIRENS source section. Comparison of simulation results with experiment observations provides an understanding of the physical mechanisms forming the particulate and indicates if mechanisms other than those in the model were present in the experiment. Key results from this comparison were: the predicted amount of mass mobilized from the source section was generally much lower than that measured, the calculated and measured particle count median diameters were similar at various locations in the expansion chamber, and the measured standard deviations were larger than those predicted by the model. These results implicate that other mechanisms (e.g., mobilization of melted material) in addition to ablation were responsible for mass removal in the source section, a large number of the measured particles were

  15. Numerical Analysis of Nucleate Boiling on High Heat-Flux and High Subcooling Condition for Reactivity Initiation Accident

    SciTech Connect

    Heo, S.; Koshizuka, S.; Oka, Y.

    2002-07-01

    This paper shows the numerical simulation study on the growth of the bubble in the transient pool boiling using MPS-MAFL method. The growth process of a bubble with the different initial radii is calculated in a high heat-flux and high subcooling condition expected in nuclear reactor core during RIA. The smaller initial radius is, the earlier the growth starts. The initial bubble radius has little effect on the growth initiation time and the bubble departure radius. (authors)

  16. Diamond monochromator for high heat flux synchrotron x-ray beams

    SciTech Connect

    Khounsary, A.M.; Smither, R.K.; Davey, S.; Purohit, A.

    1992-12-01

    Single crystal silicon has been the material of choice for x-ray monochromators for the past several decades. However, the need for suitable monochromators to handle the high heat load of the next generation synchrotron x-ray beams on the one hand and the rapid and on-going advances in synthetic diamond technology on the other make a compelling case for the consideration of a diamond mollochromator system. In this Paper, we consider various aspects, advantage and disadvantages, and promises and pitfalls of such a system and evaluate the comparative an monochromator subjected to the high heat load of the most powerful x-ray beam that will become available in the next few years. The results of experiments performed to evaluate the diffraction properties of a currently available synthetic single crystal diamond are also presented. Fabrication of diamond-based monochromator is within present technical means.

  17. Integrated computational study of ultra-high heat flux cooling using cryogenic micro-solid nitrogen spray

    NASA Astrophysics Data System (ADS)

    Ishimoto, Jun; Oh, U.; Tan, Daisuke

    2012-10-01

    A new type of ultra-high heat flux cooling system using the atomized spray of cryogenic micro-solid nitrogen (SN2) particles produced by a superadiabatic two-fluid nozzle was developed and numerically investigated for application to next generation super computer processor thermal management. The fundamental characteristics of heat transfer and cooling performance of micro-solid nitrogen particulate spray impinging on a heated substrate were numerically investigated and experimentally measured by a new type of integrated computational-experimental technique. The employed Computational Fluid Dynamics (CFD) analysis based on the Euler-Lagrange model is focused on the cryogenic spray behavior of atomized particulate micro-solid nitrogen and also on its ultra-high heat flux cooling characteristics. Based on the numerically predicted performance, a new type of cryogenic spray cooling technique for application to a ultra-high heat power density device was developed. In the present integrated computation, it is clarified that the cryogenic micro-solid spray cooling characteristics are affected by several factors of the heat transfer process of micro-solid spray which impinges on heated surface as well as by atomization behavior of micro-solid particles. When micro-SN2 spraying cooling was used, an ultra-high cooling heat flux level was achieved during operation, a better cooling performance than that with liquid nitrogen (LN2) spray cooling. As micro-SN2 cooling has the advantage of direct latent heat transport which avoids the film boiling state, the ultra-short time scale heat transfer in a thin boundary layer is more possible than in LN2 spray. The present numerical prediction of the micro-SN2 spray cooling heat flux profile can reasonably reproduce the measurement results of cooling wall heat flux profiles. The application of micro-solid spray as a refrigerant for next generation computer processors is anticipated, and its ultra-high heat flux technology is expected

  18. Facility for high heat flux testing of irradiated fusion materials and components using infrared plasma arc lamps

    SciTech Connect

    Sabau, Adrian S; Ohriner, Evan Keith; Kiggans, Jim; Harper, David C; Snead, Lance Lewis; Schaich, Charles Ross

    2014-01-01

    A new high-heat flux testing facility using water-wall stabilized high-power high-pressure argon Plasma Arc Lamps (PALs) has been developed for fusion applications. It can handle irradiated plasma facing component materials and mock-up divertor components. Two PALs currently available at ORNL can provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over a heated area of 9x12 and 1x10 cm2, respectively, which are fusion-prototypical steady state heat flux conditions. The facility will be described and the main differences between the photon-based high-heat flux testing facilities, such as PALs, and the e-beam and particle beam facilities more commonly used for fusion HHF testing are discussed. The components of the test chamber were designed to accommodate radiation safety and materials compatibility requirements posed by high-temperature exposure of low levels irradiated tungsten articles. Issues related to the operation and temperature measurements during testing are presented and discussed.

  19. Facility for high-heat flux testing of irradiated fusion materials and components using infrared plasma arc lamps

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Ohriner, Evan K.; Kiggans, Jim; Harper, David C.; Snead, Lance L.; Schaich, Charles R.

    2014-04-01

    A new high-heat flux testing (HHFT) facility using water-wall stabilized high-power high-pressure argon plasma arc lamps (PALs) has been developed for fusion applications. It can accommodate irradiated plasma facing component materials and sub-size mock-up divertor components. Two PALs currently available at Oak Ridge National Laboratory can provide maximum incident heat fluxes of 4.2 and 27 MW m-2, which are prototypic of fusion steady state heat flux conditions, over a heated area of 9 × 12 and 1 × 10 cm2, respectively. The use of PAL permits the heat source to be environmentally separated from the components of the test chamber, simplifying the design to accommodate safe testing of low-level irradiated articles and materials under high-heat flux. Issues related to the operation and temperature measurements during testing of tungsten samples are presented and discussed. The relative advantages and disadvantages of this photon-based HHFT facility are compared to existing e-beam and particle beam facilities used for similar purposes.

  20. Report on the joint meeting of the Division of Development and Technology Plasma/Wall Interaction and High Heat Flux Materials and Components Task Groups

    SciTech Connect

    Wilson, K.L.

    1985-10-01

    This report of the Joint Meeting of the Division of Development and Technology Plasma/Wall Interaction and High Heat Flux Materials and Components Task Groups contains contributing papers in the following areas: Plasma/Materials Interaction Program and Technical Assessment, High Heat Flux Materials and Components Program and Technical Assessment, Pumped Limiters, Ignition Devices, Program Planning Activities, Compact High Power Density Reactor Requirements, Steady State Tokamaks, and Tritium Plasma Experiments. All these areas involve the consideration of High Heat Flux on Materials and the Interaction of the Plasma with the First Wall. Many of the Test Facilities are described as well. (LSP)

  1. High-heat-flux testing of irradiated tungsten-based materials for fusion applications using infrared plasma arc lamps

    SciTech Connect

    Sabau, Adrian S.; Ohriner, Evan K.; Kiggans, Jim; Schaich, Charles R.; Ueda, Yoshio; Harper, David C.; Katoh, Yutai; Snead, Lance L.; Byun, Thak S.

    2014-11-01

    Testing of advanced materials and component mock-ups under prototypical fusion high-heat-flux conditions, while historically a mainstay of fusion research, has proved to be quite challenging, especially for irradiated materials. A new high-heat-flux–testing (HHFT) facility based on water-wall plasma arc lamps (PALs) is now introduced for materials and small-component testing. Two PAL systems, utilizing a 12 000°C plasma arc contained in a quartz tube cooled by a spiral water flow over the inside tube surface, provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over areas of 9×12 and 1×10 cm2, respectively. This paper will present the overall design and implementation of a PAL-based irradiated material target station (IMTS). The IMTS is primarily designed for testing the effects of heat flux or thermal cycling on material coupons of interest, such as those for plasma-facing components. Temperature results are shown for thermal cycling under HHFT of tungsten coupon specimens that were neutron irradiated in HFIR. Finally, radiological surveys indicated minimal contamination of the 36×36×18 cm test section, demonstrating the capability of the new facility to handle irradiated specimens at high temperature.

  2. High-heat-flux testing of irradiated tungsten-based materials for fusion applications using infrared plasma arc lamps

    DOE PAGES

    Sabau, Adrian S.; Ohriner, Evan K.; Kiggans, Jim; ...

    2014-11-01

    Testing of advanced materials and component mock-ups under prototypical fusion high-heat-flux conditions, while historically a mainstay of fusion research, has proved to be quite challenging, especially for irradiated materials. A new high-heat-flux–testing (HHFT) facility based on water-wall plasma arc lamps (PALs) is now introduced for materials and small-component testing. Two PAL systems, utilizing a 12 000°C plasma arc contained in a quartz tube cooled by a spiral water flow over the inside tube surface, provide maximum incident heat fluxes of 4.2 and 27 MW/m2 over areas of 9×12 and 1×10 cm2, respectively. This paper will present the overall design andmore » implementation of a PAL-based irradiated material target station (IMTS). The IMTS is primarily designed for testing the effects of heat flux or thermal cycling on material coupons of interest, such as those for plasma-facing components. Temperature results are shown for thermal cycling under HHFT of tungsten coupon specimens that were neutron irradiated in HFIR. Finally, radiological surveys indicated minimal contamination of the 36×36×18 cm test section, demonstrating the capability of the new facility to handle irradiated specimens at high temperature.« less

  3. Thermal Control Utilizing an Thermal Control Utilizing an Two-Phase Loop with High Heat Flux Source

    NASA Technical Reports Server (NTRS)

    Jeong, Seong-Il; Didion, Jeffrey

    2004-01-01

    The electric field applied in dielectric fluids causes an imbalance in the dissociation-recombination reaction generated free space charges. The generated charges are redistributed by the applied electric field resulting in the heterocharge layers in the Vicinity of the electrodes. Proper design of the electrodes generates net axial flow motion pumping the fluid. The electrohydrodynamic (EHD) conduction pump is a new device that pumps dielectric fluids utilizing heterocharge layers formed by imposition of electrostatic fields. This paper evaluates the experimental performance of a two-phase breadboard thermal control loop consisting of an EHD conduction pump, condenser, pre-heater, high heat flux evaporator (HE), transport lines, and reservoir (accumulator). The generated pressure head and the maximum applicable heat flux are experimentally determined at various applied voltages and sink temperatures. Recovery from dryout condition by increasing the applied voltage to the pump is also demonstrated.

  4. Thermal behavior and temperature measurements of melting beryllium plasma-facing components exposed to high heat flux

    NASA Astrophysics Data System (ADS)

    Gauthier, E.; Pocheau, C.; Kovari, M.; Barnard, J. M.; Crowley, B.; Godwin, J.; Lane, C.

    2015-08-01

    The emissivity of metallic materials is low and varies with temperature and wavelength inducing errors on surface temperature measurements. High heat flux experiments on beryllium were carried out to investigate the thermal behavior of bulk Be tiles. Thermal modeling aiming at determining the surface and bulk temperatures have been performed using ANSYS®. A Be tile was exposed to heat flux with power density ranging between 1 and 7 MW/m2. Surface temperatures were measured using an infrared camera in the 3-5 μm range and two-color pyrometers, one at short wavelengths (1.5-1.7 μm) and one at mid IR range wavelengths (2-4 μm) range. Both the IR camera and two-color pyrometers do not provide accurate temperature measurements on melted Be due to changes in the emissivities and emissivity ratio induced by surface modifications.

  5. A Review of Boiling Heat Transfer Processes at High Heat Flux

    DTIC Science & Technology

    1991-04-01

    the limit of nucleate boiling (point C) and point 0 which is known as the Leidenfrost point. The path between the points is dependent on numerous...heat flux controlled system. 4 Point Elies on a portion of the boiling curve known as film boiling. Beginning at the Leidenfrost point (point D) heat

  6. Investigation of Instabilities and Heat Transfer Phenomena in Supercritical Fuels at High Heat Flux and Temperatures

    NASA Technical Reports Server (NTRS)

    Linne, Diane L.; Meyer, Michael L.; Braun, Donald C.; Keller, Dennis J.

    2000-01-01

    A series of heated tube experiments was performed to investigate fluid instabilities that occur during heating of supercritical fluids. In these tests, JP-7 flowed vertically through small diameter tubes at supercritical pressures. Test section heated length, diameter, mass flow rate, inlet temperature, and heat flux were varied in an effort to determine the range of conditions that trigger the instabilities. Heat flux was varied up to 4 BTU/sq in./s, and test section wall temperatures reached as high as 1950 F. A statistical model was generated to explain the trends and effects of the control variables. The model included no direct linear effect of heat flux on the occurrence of the instabilities. All terms involving inlet temperature were negative, and all terms involving mass flow rate were positive. Multiple tests at conditions that produced instabilities provided inconsistent results. These inconsistencies limit the use of the model as a predictive tool. Physical variables that had been previously postulated to control the onset of the instabilities, such as film temperature, velocity, buoyancy, and wall-to-bulk temperature ratio, were evaluated here. Film temperatures at or near critical occurred during both stable and unstable tests. All tests at the highest velocity were stable, but there was no functional relationship found between the instabilities and velocity, or a combination of velocity and temperature ratio. Finally, all of the unstable tests had significant buoyancy at the inlet of the test section, but many stable tests also had significant buoyancy forces.

  7. Pool boiling with high heat flux enabled by a porous artery structure

    NASA Astrophysics Data System (ADS)

    Bai, Lizhan; Zhang, Lianpei; Lin, Guiping; Peterson, G. P.

    2016-06-01

    A porous artery structure utilizing the concept of "phase separation and modulation" is proposed to enhance the critical heat flux of pool boiling. A series of experiments were conducted on a range of test articles in which multiple rectangular arteries were machined directly into the top surface of a 10.0 mm diameter copper rod. The arteries were then covered by a 2.0 mm thickness microporous copper plate through silver brazing. The pool wall was fabricated from transparent Pyrex glass to allow a visualization study, and water was used as the working fluid. Experimental results confirmed that the porous artery structure provided individual flow paths for the liquid supply and vapor venting, and avoided the detrimental effects of the liquid/vapor counter flow. As a result, a maximum heat flux of 610 W/cm2 over a heating area of 0.78 cm2 was achieved with no indication of dryout, prior to reaching the heater design temperature limit. Following the experimental tests, the mechanisms responsible for the boiling critical heat flux and performance enhancement of the porous artery structure were analyzed.

  8. Magnetic fusion energy plasma interactive and high heat flux components. Volume II. Technical assessment of the critical issues and problem areas in high heat flux materials and component development

    SciTech Connect

    Abdou, M.A.; Boyd, R.D.; Easor, J.R.; Gauster, W.B.; Gordon, J.D.; Mattas, R.F.; Morgan, G.D.; Ulrickson, M.A,; Watson, R.D.; Wolfer, W.G,

    1984-06-01

    A technical assessment of the critical issues and problem areas for high heat flux materials and components (HHFMC) in magnetic fusion devices shows these problems to be of critical importance for the successful operation of near-term fusion experiments and for the feasibility and attractiveness of long-term fusion reactors. A number of subgroups were formed to assess the critical HHFMC issues along the following major lines: (1) source conditions, (2) systems integration, (3) materials and processes, (4) thermal hydraulics, (5) thermomechanical response, (6) electromagnetic response, (7) instrumentation and control, and (8) test facilities. The details of the technical assessment are presented in eight chapters. The primary technical issues and needs for each area are highlighted.

  9. 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.

  10. Flash boiling from carbon foams for high-heat-flux transient cooling

    NASA Astrophysics Data System (ADS)

    Engerer, J. D.; Fisher, T. S.

    2016-07-01

    Flash boiling of a liquid pool results in an event characterized by rapid phase change and, as a result, high rates of expansion and cooling. Because of the potential advantages of such characteristics for convective heat transfer, flash boiling is considered here for the purpose of cooling transient heat loads. The event has the positive characteristics mentioned as well as rapid response (˜10 ms) and high initial rates of phase change, and then quickly decays to a steady-state regime analogous to pool boiling. The performance of the cooling mechanism is evaluated using an objective function derived from the effect of temperature on the efficiency of optical transmission in a diode-pumped solid-state laser. Statistical surrogate models based on the experimental results are used to predict optimal run conditions. Experiments using these predicted parameters show that flash boiling can maintain device temperature to within ±6.1 °C through a pulsed 5 s heat flux of 68 W cm-2 and to within ±1.4 °C for a heat flux of 39 W cm-2.

  11. High heat flux Langmuir probe array for the DIII-D divertor platesa)

    NASA Astrophysics Data System (ADS)

    Watkins, J. G.; Taussig, D.; Boivin, R. L.; Mahdavi, M. A.; Nygren, R. E.

    2008-10-01

    Two modular arrays of Langmuir probes designed to handle a heat flux of up to 25 MW/m2 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° 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 Jsat, Te, and Vf with 4 mm spatial resolution are shown.

  12. Results of high heat flux tests of tungsten divertor targets under plasma heat loads expected in ITER and tokamaks (review)

    NASA Astrophysics Data System (ADS)

    Budaev, V. P.

    2016-12-01

    Heat loads on the tungsten divertor targets in the ITER and the tokamak power reactors reach 10MW m-2 in the steady state of DT discharges, increasing to 0.6-3.5 GW m-2 under disruptions and ELMs. The results of high heat flux tests (HHFTs) of tungsten under such transient plasma heat loads are reviewed in the paper. The main attention is paid to description of the surface microstructure, recrystallization, and the morphology of the cracks on the target. Effects of melting, cracking of tungsten, drop erosion of the surface, and formation of corrugated and porous layers are observed. Production of submicron-sized tungsten dust and the effects of the inhomogeneous surface of tungsten on the plasma-wall interaction are discussed. In conclusion, the necessity of further HHFTs and investigations of the durability of tungsten under high pulsed plasma loads on the ITER divertor plates, including disruptions and ELMs, is stressed.

  13. Hybrid Heat Pipes for Lunar and Martian Surface and High Heat Flux Space Applications

    NASA Technical Reports Server (NTRS)

    Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.

    2016-01-01

    Novel hybrid wick heat pipes are developed to operate against gravity on planetary surfaces, operate in space carrying power over long distances and act as thermosyphons on the planetary surface for Lunar and Martian landers and rovers. These hybrid heat pipes will be capable of operating at the higher heat flux requirements expected in NASA's future spacecraft and on the next generation of polar rovers and equatorial landers. In addition, the sintered evaporator wicks mitigate the start-up problems in vertical gravity aided heat pipes because of large number of nucleation sites in wicks which will allow easy boiling initiation. ACT, NASA Marshall Space Flight Center, and NASA Johnson Space Center, are working together on the Advanced Passive Thermal experiment (APTx) to test and validate the operation of a hybrid wick VCHP with warm reservoir and HiK"TM" plates in microgravity environment on the ISS.

  14. Monochromators for small cross-section x-ray beams from high heat flux synchrotron sources

    SciTech Connect

    Ice, G.; Riemer, B.; Khounsary, A.

    1996-10-01

    For some x-ray experiments, only a fraction of the intense central cone of x-rays generated by high-power undulator sources can be used; the x-ray source emittance is larger than the useful emittance for the experiment. For example with microfocusing optics, or for coherence experiments, x-ray beams with cross sections less than 0.1 mm{sup 2} are desirable. With such small beams, the total thermal load is small even though the heat flux density is high. Analyses indicate that under these conditions, rather simple crystal cooling techniques can be used. We illustrate the advantages of a small beam monochromator, with a simple x-ray monochromator optimized for x-ray microdiffraction. This monochromator is designed to achieve negligible distortion when subjected to a narrow (0.1 mm wide) beam from an APS undulator operating at 100 mA. It also allows for rapid and repeatable energy scans and rapid cycling between monochromatic and white beam conditions.

  15. Qualification of high heat flux components: application to target elements of W7-X divertor

    NASA Astrophysics Data System (ADS)

    Missirlian, M.; Durocher, A.; Grosman, A.; Schlosser, J.; Boscary, J.; Escourbiac, F.; Cismondi, F.

    2007-03-01

    The development of actively cooled plasma-facing components (PFC) represents one of fusion's most challenging engineering efforts. In this frame, a high-quality bonding between the refractory armour and the heat sink is essential to ensure the heat removal capability and the thermal performances of PFC. Experience gained during manufacturing of Tore Supra actively cooled PFC led to the establishment of a qualification methodology and provided a large experience of acceptance criteria using an active infrared thermography (système d'acquisition de traitement infra-rouge, SATIR). This paper presents the application of this qualification process to the W7-X pre-series components, with the objective of assessing and defining workable acceptance criteria that enable reliable predictions of performance at the nominal heat flux requirements in W7-X. Finally, to check the reliability of the non-destructive examination (NDE) method by transient infrared thermography, the newly defined acceptance criteria were applied to W7-X pre-series target elements (batch #3). The SATIR results, benchmarked with HHF tests performed on the GLADIS ion beam facility were discussed to assess the ability to detect critical defects at the interface between tiles and heat sink.

  16. Evaluation of Cooling Conditions for a High Heat Flux Testing Facility Based on Plasma-Arc Lamps

    SciTech Connect

    Charry, Carlos H.; Abdel-khalik, Said I.; Yoda, Minami; Sabau, Adrian S.; Snead, Lance Lewis

    2015-07-31

    The new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL) uses an infrared plasma-arc lamp (PAL) to deliver incident heat fluxes as high as 27 MW/m2. The facility is being used to test irradiated plasma-facing component materials as part of the joint US-Japan PHENIX program. The irradiated samples are to be mounted on molybdenum sample holders attached to a water-cooled copper rod. Depending on the size and geometry of samples, several sample holders and copper rod configurations have been fabricated and tested. As a part of the effort to design sample holders compatible with the high heat flux (HHF) testing to be conducted at the IMTS facility, numerical simulations have been performed for two different water-cooled sample holder designs using the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) software package. The primary objective of this work is to evaluate the cooling capability of different sample holder designs, i.e. to estimate their maximum allowable incident heat flux values. 2D axisymmetric numerical simulations are performed using the realizable k-ε turbulence model and the RPI nucleate boiling model within ANSYS FLUENT 14.0. The results of the numerical model were compared against the experimental data for two sample holder designs tested in the IMTS facility. The model has been used to parametrically evaluate the effect of various operational parameters on the predicted temperature distributions. The results were used to identify the limiting parameter for safe operation of the two sample holders and the associated peak heat flux limits. The results of this investigation will help guide the development of new sample holder designs.

  17. Development of Low Conductivity and Ultra High Temperature Ceramic Coatings Using A High-Heat-Flux Testing Approach

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1990-01-01

    The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 17OOOC) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, ultra-high temperature ceramic thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity: the initial conductivity rise under a steady-state high temperature thermal gradient test due to coating sintering, and the later coating conductivity reduction under a subsequent cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on the damage accumulations and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The coating external radiation resistance is assessed based on the measured specimen temperature response under a laser heated intense radiation flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature is derived.

  18. Development of Low Conductivity and Ultra High Temperature Ceramic Coatings Using A High-Heat-Flux Testing Approach

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1990-01-01

    The development of low conductivity, robust thermal and environmental barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity and cyclic resistance at very high surface temperatures (up to 17OOOC) under large thermal gradients. In this study, a laser high-heat-flux test approach is established for evaluating advanced low conductivity, ultra-high temperature ceramic thermal and environmental barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) program. The test approach emphasizes the real-time monitoring and assessment of the coating thermal conductivity: the initial conductivity rise under a steady-state high temperature thermal gradient test due to coating sintering, and the later coating conductivity reduction under a subsequent cyclic thermal gradient test due to coating cracking/delamination. The coating system is then evaluated based on the damage accumulations and failure after the combined steady-state and cyclic thermal gradient tests. The lattice and radiation thermal conductivity of advanced ceramic coatings can also be evaluated using laser heat-flux techniques. The coating external radiation resistance is assessed based on the measured specimen temperature response under a laser heated intense radiation flux source. The coating internal radiation contribution is investigated based on the measured apparent coating conductivity increases with the coating surface test temperature under large thermal gradient test conditions. Since an increased radiation contribution is observed at these very high surface test temperatures, by varying the laser heat-flux and coating average test temperature, the complex relation between the lattice and radiation conductivity as a function of surface and interface test temperature is derived.

  19. Evaluation of Cooling Conditions for a High Heat Flux Testing Facility Based on Plasma-Arc Lamps

    DOE PAGES

    Charry, Carlos H.; Abdel-khalik, Said I.; Yoda, Minami; ...

    2015-07-31

    The new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL) uses an infrared plasma-arc lamp (PAL) to deliver incident heat fluxes as high as 27 MW/m2. The facility is being used to test irradiated plasma-facing component materials as part of the joint US-Japan PHENIX program. The irradiated samples are to be mounted on molybdenum sample holders attached to a water-cooled copper rod. Depending on the size and geometry of samples, several sample holders and copper rod configurations have been fabricated and tested. As a part of the effort to design sample holders compatiblemore » with the high heat flux (HHF) testing to be conducted at the IMTS facility, numerical simulations have been performed for two different water-cooled sample holder designs using the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) software package. The primary objective of this work is to evaluate the cooling capability of different sample holder designs, i.e. to estimate their maximum allowable incident heat flux values. 2D axisymmetric numerical simulations are performed using the realizable k-ε turbulence model and the RPI nucleate boiling model within ANSYS FLUENT 14.0. The results of the numerical model were compared against the experimental data for two sample holder designs tested in the IMTS facility. The model has been used to parametrically evaluate the effect of various operational parameters on the predicted temperature distributions. The results were used to identify the limiting parameter for safe operation of the two sample holders and the associated peak heat flux limits. The results of this investigation will help guide the development of new sample holder designs.« less

  20. GRCop-84: A High-Temperature Copper Alloy for High-Heat-Flux Applications

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2005-01-01

    GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) is a new high-temperature copper-based alloy. It possesses excellent high-temperature strength, creep resistance and low-cycle fatigue up to 700 C (1292 F) along with low thermal expansion and good conductivity. GRCop-84 can be processed and joined by a variety of methods such as extrusion, rolling, bending, stamping, brazing, friction stir welding, and electron beam welding. Considerable mechanical property data has been generated for as-produced material and following simulated braze cycles. The data shows that the alloy is extremely stable during thermal exposures. This paper reviews the major GRCop-84 mechanical and thermophysical properties and compares them to literature values for a variety of other high-temperature copper-based alloys.

  1. Numerical Study of High Heat Flux Performances of Flat-Tile Divertor Mock-ups with Hypervapotron Cooling Concept

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Liu, Xiang; Lian, Youyun; Cai, Laizhong

    2015-09-01

    The hypervapotron (HV), as an enhanced heat transfer technique, will be used for ITER divertor components in the dome region as well as the enhanced heat flux first wall panels. W-Cu brazing technology has been developed at SWIP (Southwestern Institute of Physics), and one W/CuCrZr/316LN component of 450 mm×52 mm×166 mm with HV cooling channels will be fabricated for high heat flux (HHF) tests. Before that a relevant analysis was carried out to optimize the structure of divertor component elements. ANSYS-CFX was used in CFD analysis and ABAQUS was adopted for thermal-mechanical calculations. Commercial code FE-SAFE was adopted to compute the fatigue life of the component. The tile size, thickness of tungsten tiles and the slit width among tungsten tiles were optimized and its HHF performances under International Thermonuclear Experimental Reactor (ITER) loading conditions were simulated. One brand new tokamak HL-2M with advanced divertor configuration is under construction in SWIP, where ITER-like flat-tile divertor components are adopted. This optimized design is expected to supply valuable data for HL-2M tokamak. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2011GB110001 and 2011GB110004)

  2. Recrystallization and grain growth behavior of rolled tungsten under VDE-like short pulse high heat flux loads

    NASA Astrophysics Data System (ADS)

    Yuan, Y.; Greuner, H.; Böswirth, B.; Krieger, K.; Luo, G.-N.; Xu, H. Y.; Fu, B. Q.; Li, M.; Liu, W.

    2013-02-01

    Short pulse heat loads expected for vertical displacement events (VDEs) in ITER were applied in the high heat flux (HHF) test facility GLADIS at IPP-Garching onto samples of rolled W. Pulsed neutral beams with the central heat flux of 23 MW/m2 were applied for 0.5, 1.0 and 1.5 s, respectively. Rapid recrystallization of the adiabatically loaded 3 mm thick samples was observed when the pulse duration was up to 1.0 s. Grains grew markedly following recrystallization with increasing pulse length. The recrystallization temperature and temperature dependence of the recrystallized grain size were also investigated. The results showed that the recrystallization temperature of the W grade was around 2480 °C under the applied heat loading condition, which was nearly 1150 °C higher than the conventional recrystallization temperature, and the grains were much finer. A linear relationship between the logarithm of average grain size (ln d) and the inverse of maximum surface temperature (1/Tmax) was found and accordingly the activation energy for grain growth in temperature evolution up to Tmax in 1.5 s of the short pulse HHF load was deduced to be 4.1 eV. This provided an effective clue to predict the structure evolution under short pulse HHF loads.

  3. Cu-Cr-Nb-Zr Alloy for Rocket Engines and Other High-Heat- Flux Applications

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2013-01-01

    Rocket-engine main combustion chamber liners are used to contain the burning of fuel and oxidizer and provide a stream of high-velocity gas for propulsion. The liners in engines such as the Space Shuttle Main Engine are regeneratively cooled by flowing fuel, e.g., cryogenic hydrogen, through cooling channels in the back side of the liner. The heat gained by the liner from the flame and compression of the gas in the throat section is transferred to the fuel by the liner. As a result, the liner must either have a very high thermal conductivity or a very high operating temperature. In addition to the large heat flux (>10 MW/sq m), the liners experience a very large thermal gradient, typically more than 500 C over 1 mm. The gradient produces thermally induced stresses and strains that cause low cycle fatigue (LCF). Typically, a liner will experience a strain differential in excess of 1% between the cooling channel and the hot wall. Each time the engine is fired, the liner undergoes an LCF cycle. The number of cycles can be as few as one for an expendable booster engine, to as many as several thousand for a reusable launch vehicle or reaction control system. Finally, the liners undergo creep and a form of mechanical degradation called thermal ratcheting that results in the bowing out of the cooling channel into the combustion chamber, and eventual failure of the liner. GRCop-84, a Cu-Cr-Nb alloy, is generally recognized as the best liner material available at the time of this reporting. The alloy consists of 14% Cr2Nb precipitates in a pure copper matrix. Through experimental work, it has been established that the Zr will not participate in the formation of Laves phase precipitates with Cr and Nb, but will instead react with Cu to form the desired Cu-Zr compounds. It is believed that significant improvements in the mechanical properties of GRCop-84 will be realized by adding Zr. The innovation is a Cu-Cr-Nb-Zr alloy covering the composition range of 0.8 to 8.1 weight

  4. Plasma-Materials Interactions (PMI) and High-Heat-Flux (HHF) component research and development in the US Fusion Program

    SciTech Connect

    Conn, R.W.

    1986-10-01

    Plasma particle and high heat fluxes to in-vessel components such as divertors, limiters, RF launchers, halo plasma scrapers, direct converters, and wall armor, and to the vacuum chamber itself, represent central technical issues for fusion experiments and reactors. This is well recognized and accepted. It is also well recognized that the conditions at the plasma boundary can directly influence core plasma confinement. This has been seen most dramatically, on the positive side, in the discovery of the H-mode using divertors in tokamaks. It is also reflected in the attention devoted worldwide to the problems of impurity control. Nowadays, impurities are controlled by wall conditioning, special discharge cleaning techniques, special coatings such as carbonization, the use of low-Z materials for limiters and armor, a careful tailoring of heat loads, and in some machines, through the use of divertors. All programs, all experiments, and all designers are now keenly aware that PMI and HHF issues are key to the successful performance of their machines. In this brief report we present general issues in Section 2, critical issues in Section 3, existing US PMI/HHF experiments and facilities in Section 4, US International Cooperative PMI/HHF activities in Section 5, and conclude with a discussion on major tasks in PMI/HHF in Section 6.

  5. The use of an electrothermal plasma gun to simulate the extremely high heat flux conditions of a tokamak disruption

    NASA Astrophysics Data System (ADS)

    Gilligan, John; Bourham, Mohamed

    1993-09-01

    Disruption damage conditions for future large tokamaks like ITER are nearly impossible to simulate on current tokamaks. The electrothermal plasma source SIRENS has been designed, constructed, and operated to produce high density (> 1025/m3), low temperature (1-3 eV) plasma formed by the ablation of the insulator with currents of up to 100 kA (100 μs pulse length) and energies up to 15 kJ. The source heat fluence (variable from 0.2 to 7 MJ/m2) is adequate for simulation of the thermal quench phase of plasma disruption in future fusion tokamaks. Different materials have been exposed to the high heat flux in SIRENS, where comparative erosion behavior was obtained. Vapor shield phenomena has been characterized for different materials, and the energy transmission factor through the shielding layer is obtained. The device is also equipped with a magnet capable of producing a parallel magnetic field (up to 16 T) over a 8 msec pulse length. The magnetic field is produced to decrease the turbulent energy transport through the vapor shield, which provides further reduction of surface erosion (magnetic vapor shield effect).

  6. The use of an electrothermal plasma gun to simulate the extremely high heat flux conditions of a tokamak disruption

    SciTech Connect

    Gilligan, J.; Bourham, M. )

    1993-09-01

    Disruption damage conditions for future large tokamaks like ITER are nearly impossible to simulate on current tokamaks. The electrothermal plasma source SIRENS has been designed, constructed, and operated to produce high density (> 10[sup 25]/m[sup 3]), low temperature (1-3 eV) plasma formed by the ablation of the insulator with currents of up to 100 kA (100 [mu]s pulse length) and energies up to 15 kJ. The source heat fluence (variable from 0.2 to 7 MJ/m[sup 2]) is adequate for simulation of the thermal quench phase of plasma disruption in future fusion tokamaks. Different materials have been exposed to the high heat flux in SIRENS, where comparative erosion behavior was obtained. Vapor shield phenomena has been characterized for different materials, and the energy transmission factor through the shielding layer is obtained. The device is also equipped with a magnet capable of producing a parallel magnetic field (up to 16 T) over a 8 msec pulse length. The magnetic field is produced to decrease the turbulent energy transport through the vapor shield, which provides further reduction of surface erosion (magnetic vapor shield effect).

  7. Results of high heat flux tests of tungsten divertor targets under plasma heat loads expected in ITER and tokamaks (review)

    SciTech Connect

    Budaev, V. P.

    2016-12-15

    Heat loads on the tungsten divertor targets in the ITER and the tokamak power reactors reach ~10MW m{sup −2} in the steady state of DT discharges, increasing to ~0.6–3.5 GW m{sup −2} under disruptions and ELMs. The results of high heat flux tests (HHFTs) of tungsten under such transient plasma heat loads are reviewed in the paper. The main attention is paid to description of the surface microstructure, recrystallization, and the morphology of the cracks on the target. Effects of melting, cracking of tungsten, drop erosion of the surface, and formation of corrugated and porous layers are observed. Production of submicron-sized tungsten dust and the effects of the inhomogeneous surface of tungsten on the plasma–wall interaction are discussed. In conclusion, the necessity of further HHFTs and investigations of the durability of tungsten under high pulsed plasma loads on the ITER divertor plates, including disruptions and ELMs, is stressed.

  8. Characterization of the thermal performance of high heat flux systems at the Laser Hardened Materials Evaluation Laboratory

    NASA Astrophysics Data System (ADS)

    Lander, Michael L.; Bagford, John O.; North, Mark T.; Hull, Robert J.

    1996-11-01

    When developing a high-heat-flux system, it is important to be able to test the system under relevant thermal conditions and environmental surroundings. Thermal characterization testing is best performed in parallel with analysis and design. This permits test results to impact materials selection and systems design decisions. This paper describes the thermal testing and characterization capabilities of the Laser Hardened Materials Evaluation Laboratory located at Wright-Patterson Air Force Base, Ohio. The facility features high-power carbon dioxide (CO2$ and neodymium:glass laser systems that can be teamed with vacuum chambers, wind tunnels, mechanical loading machines and/or ambient test sites to create application-specific thermal and environmental conditions local to the material sample or system. Representative results from recently conducted test series are summarized. The test series described demonstrate the successful use of a high power CO2 laser paired with environment simulation capability to : 1) simulate the expected in-service heat load on a newly developed heat transfer device to ensure its efficient operation prior to design completion, 2) simulate the heat load expected for a laser diode array cooler, 3) produce thermal conditions needed to test a radiator concept designed for space-based operation, and 4) produce thermal conditions experienced by materials use din solid rocket motor nozzles. Test diagnostics systems used to collect thermal and mechanical response data from the test samples are also described.

  9. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    DOE PAGES

    Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; ...

    2017-05-04

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300–350 °C under a representative high heat flux (~0.66 MW/m2) during one cycle of irradiation in an un-instrumented “rabbit” capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansionmore » of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. Furthermore, the success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.« less

  10. Thermal-hydraulics modeling for prototype testing of the W7-X high heat flux scraper element

    DOE PAGES

    Clark, Emily; Lumsdaine, Arnold; Boscary, Jean; ...

    2017-07-28

    The long-pulse operation of the Wendelstein 7-X (W7-X) stellarator experiment is scheduled to begin in 2020. This operational phase will be equipped with water-cooled plasma facing components to allow for longer pulse durations. Certain simulated plasma scenarios have been shown to produce heat fluxes that surpass the technological limits on the edges of the divertor target elements during steady-state operation. In order to reduce the heat load on the target elements, the addition of a “scraper element” (SE) is under investigation. The SE is composed of 24 water-cooled carbon fiber reinforced carbon composite monoblock units. Multiple full-scale prototypes have beenmore » tested in the GLADIS high heat flux test facility. Previous computational studies revealed discrepancies between the simulations and experimental measurements. In this work, single-phase thermal-hydraulics modeling was performed in ANSYS CFX to identify potential causes for such discrepancies. Possible explanations investigated were the effects of a non-uniform thermal contact resistance and a potential misalignment of the monoblock fibers. And while the difference between the experimental and computational results was not resolved by a non-uniform thermal contact resistance, the computational results provided insight into the potential performance of a W7-X monoblock unit. Circumferential temperature distributions highlighted the expected boiling regions of such a unit. Finally, simulations revealed that modest angles of fiber misalignment in the monoblocks result in asymmetries at the unit edges and provide temperature differences similar to the experimental results.« less

  11. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    NASA Astrophysics Data System (ADS)

    Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; Deck, Christian P.; Katoh, Yutai; Terrani, Kurt A.

    2017-08-01

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300-350 °C under a representative high heat flux (∼0.66 MW/m2) during one cycle of irradiation in an un-instrumented ;rabbit; capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. The success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.

  12. High heat flux experiment on B4C-converted carbon based materials for plasma facing materials of JT-60U

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazuyuki; Ishikawa, Hiroshi; Ando, Toshiro; Satoh, Kazuyoshi; Yokoyama, Kenji; Suzuki, Satoshi; Dairakum, Masayuki; Araki, Masanori; Akiba, Masato

    1994-03-01

    High heat flux experiments have been previously carried out on three kinds, namely low pressure plasma spray (LPPS), chemical vapor deposition (CVD) and conversion (CVR) methods, of B4C-overlaid CFC's using the JAERI electron beam irradiation system (JEBIS). As a result, it turned out that CVR method has the best adhesion property between B4C layer and bulk carbon. However, thicker B4C layer is necessary to use in long period as the divertor tiles of JT-60U. The purpose of this experiment is to investigate the thermal property of B4C-converted carbon based materials which have thicker B4C layer than the previous experiments. Irradiations were performed under two different heating conditions, namely in the normal condition (5-20 MW/m(exp 2), 5 s) and in the disruption conditions (1100-1600 MW/m(exp 2), 2-3 ms). The dimensions of the samples were 25 mm x 25 mm x 25 mm, and B4C-converted layers were made on the three kinds of CFC's and fifth kinds of isotropic graphites. The thickness of B4C layer was 150-1300 (mu)m. Measurements were made with respect to the weight loss, changes of the surface morphology and the surface temperature. In the normal condition, the damages such as surface melting and exfoliation were not observed on the samples which have B4C layer below 600 (mu)m in thickness. In the disruption condition, melting and exfoliation were observed on the surfaces of the samples whose substrates were PD-330S, PD-600S and HCB-5S, and melting was observed on the surfaces of the samples whose substrates were PCC-2S, MFC-1, MCI-felt, ETP-10 and STP-60. It is considered that the porous layer in the B4C layer caused the severe exfoliation from the measurement of the surface composition.

  13. Physical mechanisms of longitudinal vortexes formation, appearance of zones with high heat fluxes and early transition in hypersonic flow over delta wing with blunted leading edges

    NASA Astrophysics Data System (ADS)

    Alexandrov, S. V.; Vaganov, A. V.; Shalaev, V. I.

    2016-10-01

    Processes of vortex structures formation and they interactions with the boundary layer in the hypersonic flow over delta wing with blunted leading edges are analyzed on the base of experimental investigations and numerical solutions of Navier-Stokes equations. Physical mechanisms of longitudinal vortexes formation, appearance of abnormal zones with high heat fluxes and early laminar turbulent transition are studied. These phenomena were observed in many high-speed wind tunnel experiments; however they were understood only using the detailed analysis of numerical modeling results with the high resolution. Presented results allowed explaining experimental phenomena. ANSYS CFX code (the DAFE MIPT license) on the grid with 50 million nodes was used for the numerical modeling. The numerical method was verified by comparison calculated heat flux distributions on the wing surface with experimental data.

  14. Experimental results and a self-consistent model of evaporation and high heat flux extraction by evaporating flow in a micro-grooved blade

    NASA Astrophysics Data System (ADS)

    Monazami, Reza; Saadat, Mehdi; Zhu, Jianzhong; Haj-Hariri, Hossein

    2015-11-01

    The problem of evaporation from a vertical micro-grooved blade heated from above is investigated. The required superheat to handle the incoming flux is calculated using the results of the study by Monazami and Haj-Hariri (2012). The relation between the applied heat flux, dry-out length and the maximum equilibrium temperature for several geometries and working fluids are studied. Furthermore, a computational study of the evaporating meniscus is conducted to evaluate the evaporation rates and dissipated heat flux at the liquid-vapor interface. The computational study accounts for the flow and heat transfer in both liquid and vapor phases. The results of this study indicate that the micro-grooved structure can dissipate heat fluxes as high as 10MW/m2 for superheats as low as 5 degrees Kelvin. Experiments are conducted to verify the computational and analytical results. The findings of this work are applicable to the design of thermal management systems for high heat flux applications. Partially supported by the MAXNET Energy Partnership (Max Planck Institute and UVA).

  15. Computation of full-coverage film-cooled airfoil temperatures by two methods and comparison with high heat flux data

    NASA Technical Reports Server (NTRS)

    Gladden, H. J.; Yeh, F. C.; Austin, P. J., Jr.

    1987-01-01

    Two methods were used to calculate the heat flux to full-coverage film cooled airfoils and, subsequently, the airfoil wall temperatures. The calculated wall temperatures were compared to measured temperatures obtained in the Hot Section Facility operating at real engine conditions. Gas temperatures and pressures up to 1900 K and 18 atm with a Reynolds number up to 1.9 million were investigated. Heat flux was calculated by the convective heat transfer coefficient adiabatic wall method and by the superposition method which incorporates the film injection effects in the heat transfer coefficient. The results of the comparison indicate the first method can predict the experimental data reasonably well. However, superposition overpredicted the heat flux to the airfoil without a significant modification of the turbulent Prandtl number. The results suggest that additional research is required to model the physics of full-coverage film cooling where there is significant temperature/density differences between the gas and the coolant.

  16. Large cooling differentials and high heat flux capability with p-type Bi2Te3/Sb2Te3 and n-type Bi2Te3/Bi2SexTe3-x Superlattice Thermoelectric Devices

    NASA Astrophysics Data System (ADS)

    Bulman, Gary; Siivola, Ed; Wiitala, Ryan; Grant, Brian; Pierce, Jonathan; Venkatasubramanian, Rama

    2007-03-01

    Thin film superlattice (SL) based thermoelectric (TE) devices offer the potential for improved efficiency and high heat flux cooling over conventional bulk materials. Recently, we have demonstrated external cooling of 55K and heat pumping capacity of 128 W/cm^2. These high heat fluxes in thin film devices, while attractive for cooling hot-spots in electronics, also make the device performance sensitive to various thermal resistances in the device structure. We will discuss advances in the cooling performance of Bi2Te3-based SL TE devices and describe a method to extract device material parameters, including thermal resistance, from measurements of their δT-I-V characteristics. These parameters will be compared to values obtained through Hall and Seebeck coefficient measurement on epitaxial materials. Results will be presented for both single couple and multi-couple modules, as well as multi-stage cascaded devices made with these materials. Single stage cooling couples with δTmax of 57.8K (Tc˜242K) and multi-stage modules with δTmax˜92.2K (Tc˜209K) have been measured. G.E. Bulman, E. Siivola, B. Shen and R. Venkatasubramanian, Appl. Phys. Lett. 89, 122117 (2006).

  17. An augmented Young-Laplace model of an evaporating meniscus in a micro-channel with high heat flux

    NASA Technical Reports Server (NTRS)

    Wayner, P. C., Jr.; Plawsky, J.; Schonberg, J. A.; Dasgupta, S.

    1993-01-01

    High flux evaporations from a steady meniscus formed in a 2 micron channel is modeled using the augmented Young-Laplace equation. The heat flux is found to be a function of the long range van der Waals dispersion force which represents interfacial conditions between heptane and various substrates. Heat fluxes of (1.3-1.6) x 10(exp 6) W/m(exp 2) based on the width of the channel are obtained for heptane completely wetting the substrate at 100 C. Small channels are used to obtain these large fluxes. Even though the real contact angle is 0 deg, the apparent contact angle is found to vary between 24.8 deg and 25.6 deg. The apparent contact angle, which represents viscous losses near the contact line, has a large effect on the heat flow rate because of its effect on capillary suction and the area of the meniscus. The interfacial heat flux is modeled using kinetic theory for the evaporation rate. The superheated state depends on the temperature and the pressure of the liquid phase. The liquid pressure differs from the pressure of the vapor phase due to capillarity and long range van der Waals dispersion forces which are relevant in the ultra think film formed at the leading edge of the meniscus. Important pressure gradients in the thin film cause a substantial apparent contact angle for a complete wetting system. The temperature of the liquid is related to the evaporation rate and to the substrate temperature through the steady heat conduction equation. Conduction in the liquid phase is calculated using finite element analysis except in the vicinity of the thin film. A lubrication theory solution for the thin film is combined with the finite element analysis by the method of matched asymptotic expansions.

  18. Electron Flux of Radiation Belts Animation

    NASA Image and Video Library

    This animation shows meridional (from north-south) plane projections of the REPT-A and REPT-B electron flux values. The animation first shows the expected two-belt Van Allen zone structure; from Se...

  19. Mechanical properties and microstructure of copper alloys and copper alloy-stainless steel laminates for fusion reactor high heat flux applications

    NASA Astrophysics Data System (ADS)

    Leedy, Kevin Daniel

    A select group of copper alloys and bonded copper alloy-stainless steel panels are under consideration for heat sink applications in first wall and divertor structures of a planned thermonuclear fusion reactor. Because these materials must retain high strengths and withstand high heat fluxes, their material properties and microstructures must be well understood. Candidate copper alloys include precipitate strengthened CuNiBe and CuCrZr and dispersion strengthened Cu-Alsb2Osb3 (CuAl25). In this study, uniaxial mechanical fatigue tests were conducted on bulk copper alloy materials at temperatures up to 500sp°C in air and vacuum environments. Based on standardized mechanical properties measurement techniques, a series of tests were also implemented to characterize copper alloy-316L stainless steel joints produced by hot isostatic pressing or by explosive bonding. The correlation between mechanical properties and the microstructure of fatigued copper alloys and the interface of copper alloy-stainless steel laminates was examined. Commercial grades of these alloys were used to maintain a degree of standardization in the materials testing. The commercial alloys used were OMG Americas Glidcop CuAl25 and CuAl15; Brush Wellman Hycon 3HP and Trefimetaux CuNiBe; and Kabelmetal Elbrodur and Trefimetaux CuCrZr. CuAl25 and CuNiBe alloys possessed the best combination of fatigue resistance and microstructural stability. The CuAl25 alloy showed only minimal microstructural changes following fatigue while the CuNiBe alloy consistently exhibited the highest fatigue strength. Transmission electron microscopy observations revealed that small matrix grain sizes and high densities of submicron strengthening phases promoted homogeneous slip deformation in the copper alloys. Thus, highly organized fatigue dislocation structure formation, as commonly found in oxygen-free high conductivity Cu, was inhibited. A solid plate of CuAl25 alloy hot isostatically pressed to a 316L stainless steel

  20. Dynamic vacuum analysis for APS high heat flux beamline front ends using optical ray-tracing simulation methods

    SciTech Connect

    Xu, S.; Nielsen, R.W.

    1992-01-01

    The high-power and high-flux x-ray beams produced by third generation synchrotron radiation sources such as the Advanced Photon Source (APS) can cause significantly high gas desorption rates on beamline front-end components if beam missteering occurs. The effect of this gas desorption needs to be understood for dynamic vacuum analysis. To simulate beam missteering conditions, optical ray-tracing methods have been employed. The results of the ray-tracing analysis have been entered into a system-oriented vacuum program to provide dynamic vacuum calculations for determination of pumping requirements for the beamline front-ends. The APS will provide several types of synchrotron radiation sources, for example, undulators, wigglers, and bending magnets. For the purpose of this study, the wiggler source was chosen as a worst case'' scenario due to its high photon flux, high beam power, and relatively large beam cross section.

  1. Dynamic vacuum analysis for APS high heat flux beamline front ends using optical ray-tracing simulation methods

    SciTech Connect

    Xu, S.; Nielsen, R.W.

    1992-09-01

    The high-power and high-flux x-ray beams produced by third generation synchrotron radiation sources such as the Advanced Photon Source (APS) can cause significantly high gas desorption rates on beamline front-end components if beam missteering occurs. The effect of this gas desorption needs to be understood for dynamic vacuum analysis. To simulate beam missteering conditions, optical ray-tracing methods have been employed. The results of the ray-tracing analysis have been entered into a system-oriented vacuum program to provide dynamic vacuum calculations for determination of pumping requirements for the beamline front-ends. The APS will provide several types of synchrotron radiation sources, for example, undulators, wigglers, and bending magnets. For the purpose of this study, the wiggler source was chosen as a ``worst case`` scenario due to its high photon flux, high beam power, and relatively large beam cross section.

  2. Preliminary Heat Transfer Characteristics of RP-2 Fuel as Tested in the High Heat Flux Facility (PREPRINT)

    DTIC Science & Technology

    2005-11-21

    2005. This facility, coupled with established heated tube facilities, such as the NASA Glenn Heated Tube Facility ( HTF ) 3 and the Wright-Patterson...operation differs from the existing facilities in both construction and heating elements. Both the NASA Glenn HTF and the Wright-Patterson Phoenix Rig...ft/sec leading to heat fluxes of up to 100 BTU/in2 sec.1 In similarity to the HTF , the HHFF uses oxygen-free grade copper walled test sections

  3. Atmospheric electron flux at airplane altitude

    SciTech Connect

    Enomoto, R.; Chiba, J.; Ogawa, K.; Sumiyoshi, T.; Takasaki, F. ); Kifune, T. ); Matsubara, Y. ); Nishimura, J. )

    1991-12-01

    We have developed a new detector to systematically measure the cosmic-ray electron flux at airplane altitudes. We loaded a lead-glass-based electron telescope onto a commercial cargo airplane. The first experiment was carried out using the air route between Narita (Japan) and Sydney (Australia); during this flight we measured the electron flux at various altitudes and latitudes. The thresholds of the electron energies were 1, 2, and 4 GeV. The results agree with a simple estimation using one-dimensional shower theory. A comparison with a Monte Carlo calculation was made.

  4. Preliminary Heat Transfer Characteristics of RP-2 Fuel as Tested in the High Heat Flux Facility (POSTPRINT)

    DTIC Science & Technology

    2005-11-21

    operational in October 2005. This facility, coupled with established heated tube facilities, such as the NASA Glenn Heated Tube Facility ( HTF ) 3 and...Facility design and operation differs from the existing facilities in both construction and heating elements. Both the NASA Glenn HTF and the Wright...flow rates of up to 450 ft/sec leading to heat fluxes of up to 100 BTU/in2 sec.1 In similarity to the HTF , the HHFF uses oxygen-free grade copper

  5. Melt layer erosion of pure and lanthanum doped tungsten under VDE-like high heat flux loads

    NASA Astrophysics Data System (ADS)

    Yuan, Y.; Greuner, H.; Böswirth, B.; Luo, G.-N.; Fu, B. Q.; Xu, H. Y.; Liu, W.

    2013-07-01

    Heat loads expected for VDEs in ITER were applied in the neutral beam facility GLADIS at IPP Garching. Several ˜3 mm thick rolled pure W and W-1 wt% La2O3 plates were exposed to pulsed hydrogen beams with a central heat flux of 23 MW/m2 for 1.5-1.8 s. The melting thresholds are determined, and melt layer motion as well as material structure evolutions are shown. The melting thresholds of the two W grades are very close in this experimental setup. Lots of big bubbles with diameters from several μm to several 10 μm in the re-solidified layer of W were observed and they spread deeper with increasing heat flux. However, for W-1 wt% La2O3, no big bubbles were found in the corrugated melt layer. The underlying mechanisms referred to the melt layer motion and bubble issues are tentatively discussed based on comparison of the erosion characteristics between the two W grades.

  6. Micro- and nano-scale damage on the surface of W divertor component during exposure to high heat flux loads with He

    NASA Astrophysics Data System (ADS)

    Li, C.; Greuner, H.; Zhao, S. X.; Böswirth, B.; Luo, G. N.; Zhou, X.; Jia, Y. Z.; Liu, X.; Liu, W.

    2015-11-01

    Micro- and nano-scale surface damage on a W divertor component sample exposed to high heat flux loads generated with He atoms has been investigated through SEM, EBSD, AFM and FIB-SEM. The component sample was supplied by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and AT&M company, China, and the loading experiment was performed in the GLADIS facility at IPP Garching, Germany. Two typical damage structures were observed on the surface: the first one is characterized by obvious blisters and some grooves formed from ruptured blisters, and the other one is a kind of porous structure accompanying with at least ∼25 nm surface material loss. As the grain orientation is further away from <111>, the damage morphology gradually changes from the former structure to the latter. The possible damage mechanism is discussed.

  7. High heat flux test with HIP-bonded Ferritic Martensitic Steel mock-up for the first wall of the KO HCML TBM

    NASA Astrophysics Data System (ADS)

    Won Lee, Dong; Dug Bae, Young; Kwon Kim, Suk; Yun Shin, Hee; Guen Hong, Bong; Cheol Bang, In

    2011-10-01

    In order for a Korean Helium Cooled Molten Lithium (HCML) Test Blanket Module (TBM) to be tested in the International Thermonuclear Experimental Reactor (ITER), fabrication method for the TBM FW such as Hot Isostatic Pressing (HIP, 1050 °C, 100 MPa, 2 h) has been developed including post HIP heat treatment (PHHT, normalizing at 950 °C for 2 h and tempering at 750 °C for 2 h) with Ferritic Martensitic Steel (FMS). Several mock-ups were fabricated using the developed methods and one of them, three-channel mock-up, was used for performing a High Heat Flux (HHF) test to verify the joint integrity. Test conditions were determined using the commercial code, ANSYS-11, and the test was performed in the Korea Heat Load Test (KoHLT) facility, which was used a radiation heating with a graphite heater. The mock-up survived up to 1000 cycles under 1.0 MW/m 2 heat flux and there is no delamination or failure during the test.

  8. A comparison of the heat transfer capabilities of two manufacturing methods for high heat flux water-cooled devices

    SciTech Connect

    McKoon, R.H.

    1986-10-01

    An experimental program was undertaken to compare the heat transfer characteristics of water-cooled copper devices manufactured via conventional drilled passage construction and via a technique whereby molten copper is cast over a network of preformed cooling tubes. Two similar test blocks were constructed; one using the drilled passage technique, the other via casting copper over Monel pipe. Each test block was mounted in a vacuum system and heated uniformly on the top surface using a swept electron beam. From the measured absorbed powers and resultant temperatures, an overall heat transfer coefficient was calculated. The maximum heat transfer coefficient calculated for the case of the drilled passage test block was 2534 Btu/hr/ft/sup 2///sup 0/F. This corresponded to an absorbed power density of 320 w/cm/sup 2/ and resulted in a maximum recorded copper temperature of 346/sup 0/C. Corresponding figures for the cast test block were 363 Btu/hr/ft/sup 2///sup 0/F, 91 w/cm/sup 2/, and 453/sup 0/C.

  9. Proceedings of 1999 U.S./Japan Workshop (99FT-05) On High Heat Flux Components and Plasma Surface Interactions for Next Fusion Devices

    SciTech Connect

    NYGREN,RICHARD E.; STAVROS,DIANA T.

    2000-06-01

    The 1999 US-Japan Workshop on High Heat Flux Components and Plasma Surface Interactions in Next Step Fusion Devices was held at the St. Francis Hotel in Santa Fe, New Mexico, on November 1-4, 1999. There were 42 presentations as well as discussion on technical issues and planning for future collaborations. The participants included 22 researchers from Japan and the United States as well as seven researchers from Europe and Russia. There have been important changes in the programs in both the US and Japan in the areas of plasma surface interactions and plasma facing components. The US has moved away from a strong focus on the ITER Project and has introduced new programs on use of liquid surfaces for plasma facing components, and operation of NSTX has begun. In Japan, the Large Helical Device began operation. This is the first large world-class confinement device operating in a magnetic configuration different than a tokamak. In selecting the presentations for this workshop, the organizers sought a balance between research in laboratory facilities or confinement devices related to plasma surface interactions and experimental research in the development of plasma facing components. In discussions about the workshop itself, the participants affirmed their preference for a setting where ''work-in-progress'' could be informally presented and discussed.

  10. Correlation of Electrical Resistance to CMC Stress-Strain and Fracture Behavior Under High Heat-Flux Thermal and Stress Gradients

    NASA Technical Reports Server (NTRS)

    Appleby, Matthew; Morscher, Gregory; Zhu, Dongming

    2015-01-01

    Because SiCSiC ceramic matrix composites (CMCs) are under consideration for use as turbine engine hot-section components in extreme environments, it becomes necessary to investigate their performance and damage morphologies under complex loading and environmental conditions. Monitoring of electrical resistance (ER) has been shown as an effective tool for detecting damage accumulation of woven melt-infiltrated SiCSiC CMCs. However, ER change under complicated thermo-mechanical loading is not well understood. In this study a systematic approach is taken to determine the capabilities of ER as a relevant non-destructive evaluation technique for high heat-flux testing, including thermal gradients and localized stress concentrations. Room temperature and high temperature, laser-based tensile tests were conducted in which stress-dependent damage locations were determined using modal acoustic emission (AE) monitoring and compared to full-field strain mapping using digital image correlation (DIC). This information is then compared with the results of in-situ ER monitoring, post-test ER inspection and fractography in order to correlate ER response to convoluted loading conditions and damage evolution.

  11. HF Accelerated Electron Fluxes, Spectra, and Ionization

    NASA Astrophysics Data System (ADS)

    Carlson, Herbert C.; Jensen, Joseph B.

    2015-10-01

    Wave particle interactions, an essential aspect of laboratory, terrestrial, and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich in Usp Fizicheskikh Nauk 177(11):1145-1177, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al. in J Atmos Terr Phys 44:1089-1100, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~eV, but instead to -100 times thermal energy (10 s of eV), as a consequence of inelastic collision effects on electron transport. Gurevich et al (J Atmos Terr Phys 47:1057-1070, 1985) quantified the theory of this transport effect. Merging experiment with theory in plasma physics and aeronomy, enabled prediction (Carlson in Adv Space Res 13:1015-1024, 1993) of creating artificial ionospheres once ~GW HF effective radiated power could be achieved. Eventual confirmation of this prediction (Pedersen et al. in Geophys Res Lett 36:L18107, 2009; Pedersen et al. in Geophys Res Lett 37:L02106, 2010; Blagoveshchenskaya et al. in Ann Geophys 27:131-145, 2009) sparked renewed interest in optical inversion to estimate electron spectra in terrestrial (Hysell et al. in J Geophys Res Space Phys 119:2038-2045, 2014) and planetary (Simon et al. in Ann Geophys 29:187-195, 2011) atmospheres. Here we present our unpublished optical data, which combined with our modeling, lead to conclusions that should meaningfully improve future estimates of the spectrum of HF accelerated electron fluxes. Photometric imaging data can significantly improve detection of emissions near ionization threshold, and confirm depth of penetration of accelerated electrons many km below the excitation altitude. Comparing observed to modeled emission altitude shows future experiments need electron density profiles

  12. Electron transport fluxes in potato plateau regime

    SciTech Connect

    Shaing, K.C.; Hazeltine, R.D.

    1997-12-01

    Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100{percent} bootstrap current. {copyright} {ital 1997 American Institute of Physics.}

  13. Dependence of Electron Flux on Electron Temperature in Spacecraft Charging

    DTIC Science & Technology

    2009-01-01

    those at lower energies fall . For a given energy E, the maxi- mum of the flux curve is located at T=(2£/3). in agreement with Eq. (111. Figure 0... Bastille Day event, 2000. The spacecraft potential (negative kV) rises whenever the electron tempera- ture exceeds a critical value (from Ref. 7

  14. Electron energy flux in the solar wind.

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Sugiura, M.

    1971-01-01

    Description of studies of electrons between 10 eV and 9.9 keV in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy-flux density to exceed the heat flow due to thermal electrons. In one such event, the observations are shown to be consistent with the solar-electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary-field line, a comparatively large energy flux along the field toward the sun is observed, but the heat flow remains outwardly directed during this time interval. In either situation the heat flow is found to be consistent with measurements made on Vela satellites by a different method. These values, less than .01 ergs/sq cm/sec, are sufficiently low to require modifications to the Spitzer-Harm conductivity formula for use in solar-wind theories.

  15. Flux profile scanners for scattered high-energy electrons

    NASA Astrophysics Data System (ADS)

    Hicks, R. S.; Decowski, P.; Arroyo, C.; Breuer, M.; Celli, J.; Chudakov, E.; Kumar, K. S.; Olson, M.; Peterson, G. A.; Pope, K.; Ricci, J.; Savage, J.; Souder, P. A.

    2005-11-01

    The paper describes the design and performance of flux integrating Cherenkov scanners with air-core reflecting light guides used in a high-energy, high-flux electron scattering experiment at the Stanford Linear Accelerator Center. The scanners were highly radiation resistant and provided a good signal to background ratio leading to very good spatial resolution of the scattered electron flux profile scans.

  16. Electronic and nuclear flux densities in the H2 molecule

    NASA Astrophysics Data System (ADS)

    Hermann, G.; Paulus, B.; Pérez-Torres, J. F.; Pohl, V.

    2014-05-01

    We present a theoretical study of the electronic and nuclear flux densities of a vibrating H2 molecule after an electronic excitation by a short femtosecond laser pulse. The final state, a coherent superposition of the electronic ground state X1Σg+ and the electronic excited state B1Σu+, evolves freely and permits the partition of the electronic flux density into two competing fluxes: the adiabatic and the transition flux density. The nature of the two fluxes allows us to identify two alternating dynamics of the electronic motion, occurring on the attosecond and the femtosecond time scales. In contradistinction to the adiabatic electronic flux density, the transition electronic flux density shows a dependence on the carrier-envelope phase of the laser field, encoding information of the interaction of the electrons with the electric field. Furthermore, the nuclear flux density displays multiple reversals, a quantum effect recently discovered by Manz et al. [J. Manz, J. F. Pérez-Torres, and Y. Yang, Phys. Rev. Lett. 111, 153004 (2013), 10.1103/PhysRevLett.111.153004], calling for investigation of the electronic flux density.

  17. Developing structural, high-heat flux and plasma facing materials for a near-term DEMO fusion power plant: The EU assessment

    NASA Astrophysics Data System (ADS)

    Stork, D.; Agostini, P.; Boutard, J. L.; Buckthorpe, D.; Diegele, E.; Dudarev, S. L.; English, C.; Federici, G.; Gilbert, M. R.; Gonzalez, S.; Ibarra, A.; Linsmeier, Ch.; Li Puma, A.; Marbach, G.; Morris, P. F.; Packer, L. W.; Raj, B.; Rieth, M.; Tran, M. Q.; Ward, D. J.; Zinkle, S. J.

    2014-12-01

    The findings of the EU 'Materials Assessment Group' (MAG), within the 2012 EU Fusion Roadmap exercise, are discussed. MAG analysed the technological readiness of structural, plasma facing and high heat flux materials for a DEMO concept to be constructed in the early 2030s, proposing a coherent strategy for R&D up to a DEMO construction decision. A DEMO phase I with a 'Starter Blanket' and 'Starter Divertor' is foreseen: the blanket being capable of withstanding ⩾2 MW yr m-2 fusion neutron fluence (∼20 dpa in the front-wall steel). A second phase ensues for DEMO with ⩾5 MW yr m-2 first wall neutron fluence. Technical consequences for the materials required and the development, testing and modelling programmes, are analysed using: a systems engineering approach, considering reactor operational cycles, efficient maintenance and inspection requirements, and interaction with functional materials/coolants; and a project-based risk analysis, with R&D to mitigate risks from material shortcomings including development of specific risk mitigation materials. The DEMO balance of plant constrains the blanket and divertor coolants to remain unchanged between the two phases. The blanket coolant choices (He gas or pressurised water) put technical constraints on the blanket steels, either to have high strength at higher temperatures than current baseline variants (above 650 °C for high thermodynamic efficiency from He-gas coolant), or superior radiation-embrittlement properties at lower temperatures (∼290-320 °C), for construction of water-cooled blankets. Risk mitigation proposed would develop these options in parallel, and computational and modelling techniques to shorten the cycle-time of new steel development will be important to achieve tight R&D timescales. The superior power handling of a water-cooled divertor target suggests a substructure temperature operating window (∼200-350 °C) that could be realised, as a baseline-concept, using tungsten on a copper

  18. Electron flux in molecules induced by nuclear motion

    NASA Astrophysics Data System (ADS)

    Okuyama, Michihiro; Takatsuka, Kazuo

    2009-07-01

    As a general tool for analysis of chemical reactions from the view point of electron wavepacket dynamics, electron flux within a molecule is numerically realized in terms of physically time-dependent electronic wavefunctions given by the semiclassical Ehrenfest theory. These wavefunctions are synchronized with real time motion of molecular nuclei through the nuclear kinematic coupling (nonadiabatic elements). Since the standard quantum flux gives only a null field for a real-valued electronic eigenfunction, we extend the definition of flux such that the essential information of dynamical flow of electrons can be retrieved even from adiabatic electronic wavefunctions calculated in the scheme of the so-called ab initio molecular dynamics.

  19. Exploring ISEE-3 magnetic cloud polarities with electron heat fluxes

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

    1999-06-01

    We have used solar wind electron heat fluxes to determine the magnetic polarities of the interplanetary magnetic fields (IMF) during the ISEE-3 observations in 1978-1982. That period included 14 magnetic clouds (MCs) identified by Zhang and Burlaga. The MCs have been modeled as single magnetic flux ropes, and it is generally assumed that they are magnetically closed structures with each end of the flux rope connected to the Sun. The flux rope model is valid only if the magnetic polarity of each MC does not change during the passage of ISEE-3 through the MC. We test this model with the heat flux data, using the dominant heat flux in bidirectional electron heat fluxes to determine the MC polarities. The polarity changes within at least 2, and possibly 6, of the 14 MCs, meaning that those MCs can not fit the model of a single flux rope.

  20. Surface modification and deuterium retention in reduced-activation steels under low-energy deuterium plasma exposure. Part II: steels pre-damaged with 20 MeV W ions and high heat flux

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Zhou, Z.; Sugiyama, K.; Balden, M.; Pintsuk, G.; Gasparyan, Yu.; Efimov, V.

    2017-03-01

    The reduced-activation ferritic/martensitic (RAFM) steels including Eurofer (9Cr) and oxide dispersion strengthened (ODS) steels by the addition of Y2O3 particles investigated in Part I were pre-damaged either with 20 MeV W ions at room temperature at IPP (Garching) or with high heat flux at FZJ (Juelich) and subsequently exposed to low energy (~20-200 eV per D) deuterium (D) plasma up to a fluence of 2.9  ×  1025 D m-2 in the temperature range from 290 K to 700 K. The pre-irradiation with 20 MeV W ions at room temperature up to 1 displacement per atom (dpa) has no noticeable influence on the steel surface morphology before and after the D plasma exposure. The pre-irradiation with W ions leads to the same concentration of deuterium in all kinds of investigated steels, regardless of the presence of nanoparticles and Cr content. It was found that (i) both kinds of irradiation with W ions and high heat flux increase the D retention in steels compared to undamaged steels and (ii) the D retention in both pre-damaged and undamaged steels decreases with a formation of surface roughness under the irradiation of steels with deuterium ions with incident energy which exceeds the threshold of sputtering. The increase in the D retention in RAFM steels pre-damaged either with W ions (damage up to ~3 µm) or high heat flux (damage up to ~10 µm) diminishes with increasing the temperature. It is important to mention that the near surface modifications caused by either implantation of high energy ions or a high heat flux load, significantly affect the total D retention at low temperatures or low fluences but have a negligible impact on the total D retention at elevated temperatures and high fluences because, in these cases, the D retention is mainly determined by bulk diffusion.

  1. Flux noise in SQUIDs: Electron versus nuclear spins

    NASA Astrophysics Data System (ADS)

    de Sousa, Rogerio; Laforest, Stephanie

    2015-03-01

    Superconducting Quantum Interference Devices (SQUIDs) are limited by intrinsic flux noise whose origin is unknown. We develop a method to accurately calculate the flux produced by spin impurities in realistic superconducting thin film wires, and show that the flux produced by each spin is much larger than anticipated by former calculations. Remarkably, the total flux noise power due to electron spins at the thin side surface of the wires is found to be of similar magnitude as the one due to electrons at the wide top surface of the wires. In addition, flux noise due to lattice nuclear spins in the bulk of the wires is found to be a sizable fraction of the total noise for some SQUID geometries. We discuss the relative importance of electron and nuclear spin species in determining the total noise power, and propose strategies to design SQUIDs with lower flux noise. We acknowledge support from the Canadian agency NSERC through its Discovery and Engage programs.

  2. Numerical model for swirl cooling in high-heat-flux particle beam targets and the design of a swirl-flow-based plasma limiter

    NASA Astrophysics Data System (ADS)

    Milora, S. L.; Combs, S. K.; Foster, C. A.

    1984-11-01

    An unsteady, two-dimensional heat conduction code was used to study the performance of swirl-flow-based neutral particle beam targets. The model includes the effects of two-phase heat transfer and asymmetric heating of tubular elements. The calorimeter subjected to 30-s neutral beam pulses with incident heat flux intensities of greater than or equal to 5 kW/cu cm, is modeled. The numerical results indicate that local heat fluxes in excess of 7 kW/sq cm occur at the water cooled surface on the side exposed to the beam. This exceeds critical heat flux limits for uniformly heated tubes with straight flow by approximately a factor of 5. The design of a plasma limiter based on swirl flow heat transfer is presented.

  3. Numerical model for swirl flow cooling in high-heat-flux particle beam targets and the design of a swirl-flow-based plasma limiter

    SciTech Connect

    Milora, S.L.; Combs, S.K.; Foster, C.A.

    1984-11-01

    An unsteady, two-dimensional heat conduction code has been used to study the performance of swirl-flow-based neutral particle beam targets. The model includes the effects of two-phase heat transfer and asymmetric heating of tubular elements. The calorimeter installed in the Medium Energy Test Facility, which has been subjected to 30-s neutral beam pulses with incident heat flux intensities of greater than or equal to 5 kW/cm/sup 2/, has been modeled. The numerical results indicate that local heat fluxes in excess of 7 kW/cm/sup 2/ occur at the water-cooled surface on the side exposed to the beam. This exceeds critical heat flux limits for uniformly heated tubes wih straight flow by approximately a factor of 5. The design of a plasma limiter based on swirl flow heat transfer is presented.

  4. On the kinetics of the aluminum-water reaction during exposure in high-heat flux test loops: 1, A computer program for oxidation calculations

    SciTech Connect

    Pawel, R.E.

    1988-01-01

    The ''Griess Correlation,'' in which the thickness of the corrosion product on aluminum alloy surfaces is expressed as a function of time and temperature for high-flux-reactor conditions, was rewritten in the form of a simple, general rate equation. Based on this equation, a computer program that calculates oxide-layer thickness for any given time-temperature transient was written. 4 refs.

  5. Entanglement-assisted electron microscopy based on a flux qubit

    SciTech Connect

    Okamoto, Hiroshi; Nagatani, Yukinori

    2014-02-10

    A notorious problem in high-resolution biological electron microscopy is radiation damage caused by probe electrons. Hence, acquisition of data with minimal number of electrons is of critical importance. Quantum approaches may represent the only way to improve the resolution in this context, but all proposed schemes to date demand delicate control of the electron beam in highly unconventional electron optics. Here we propose a scheme that involves a flux qubit based on a radio-frequency superconducting quantum interference device, inserted in a transmission electron microscope. The scheme significantly improves the prospect of realizing a quantum-enhanced electron microscope for radiation-sensitive specimens.

  6. Frozen flux violation, electron demagnetization and magnetic reconnection

    SciTech Connect

    Scudder, J. D.; Karimabadi, H.; Roytershteyn, V.; Daughton, W.

    2015-10-15

    We argue that the analogue in collisionless plasma of the collisional diffusion region of magnetic reconnection is properly defined in terms of the demagnetization of the plasma electrons that enable “frozen flux” slippage to occur. This condition differs from the violation of the “frozen-in” condition, which only implies that two fluid effects are involved, rather than the necessary slippage of magnetic flux as viewed in the electron frame. Using 2D Particle In Cell (PIC) simulations, this approach properly finds the saddle point region of the flux function. Our demagnetization conditions are the dimensionless guiding center approximation expansion parameters for electrons which we show are observable and determined locally by the ratio of non-ideal electric to magnetic field strengths. Proxies for frozen flux slippage are developed that (a) are measurable on a single spacecraft, (b) are dimensionless with theoretically justified threshold values of significance, and (c) are shown in 2D simulations to recover distinctions theoretically possible with the (unmeasurable) flux function. A new potentially observable dimensionless frozen flux rate, Λ{sub Φ}, differentiates significant from anecdotal frozen flux slippage. A single spacecraft observable, ϒ, is shown with PIC simulations to be essentially proportional to the unobservable local Maxwell frozen flux rate. This relationship theoretically establishes electron demagnetization in 3D as the general cause of frozen flux slippage. In simple 2D cases with an isolated central diffusion region surrounded by separatrices, these diagnostics uniquely identify the traditional diffusion region (without confusing it with the two fluid “ion-diffusion” region) and clarify the role of the separatrices where frozen flux violations do occur but are not substantial. In the more complicated guide and asymmetric 2D cases, substantial flux slippage regions extend out along, but inside of, the preferred separatrices

  7. Anisotropies in the flux of cosmic ray electrons and positrons

    NASA Astrophysics Data System (ADS)

    Manconi, S.; Di Mauro, M.; Donato, F.

    2017-05-01

    High energy cosmic ray electrons and positrons probe the local properties of our galaxy. In fact, regardless of the production mechanism, electromagnetic energy losses limit the typical propagation scale of GeV-TeV electrons and positrons to a few kpc. In the diffusion model, the presence of nearby and dominant sources may produce an observable dipole anisotropy in the cosmic ray fluxes. We present a detailed study on the role of anisotropies from nearby sources in the interpretation of present cosmic ray electron and positrons fluxes. Predictions for the dipole anisotropy from known astrophysical sources as Supernova Remnants (SNRs) and pulsars taken from the Green and the Australia Telescope National Facility (ATNF) catalogs are shown. The results are obtained from models compatible with the most recent AMS-02 data on electrons and positrons fluxes. In particular, anisotropies for single sources as well as for a distribution of catalog sources are discussed. We compare our results with current anisotropy upper limits from the Fermi-LAT and PAMELA experiments, showing that the search of anisotropy in the electron and positron fluxes represents a complementary tool to inspect the properties of close SNRs, as for example the Vela SNR.

  8. Relativistic electrons at geosynchronous orbit, interplanetary electron flux, and the 13-month Jovian synodic year

    NASA Technical Reports Server (NTRS)

    Christon, S. P.; Chenette, D. L.; Baker, D. N.; Moses, D.

    1989-01-01

    Results are reported from a search to determine the correlation, if any, between the temporal behaviors of 0.2-7 MeV or higher electrons at GEO (6.6 earth radii) and 6-10 MeV electrons in the interplanetary region near earth at the period of the Jovian synodic year (about 13 months). The 13-month intensity variation results from the synodic interplanetary magnetic field conection of earth to Jupiter. Direct compariosn of intensity-time flux profiles for the years 1976-1984, about 7 synodic Jovian electron seasons, shows that the intensity envelope of peak electron flux at GEO does not appear to be correlated to the observed 13 month intensity envelope of relativistic electron flux in the interplanetary region near earth. A persistent 13-month variation of GEO flux is not obvious, thus indicating that the intensity of electron flux at GEO is not directly and soley related to the intensity of Jovian electron flux near earth. It is concluded that dynamic erergization and redistribution processes in earth's magnetosphere must be invoked to produce the intensity variations of relativistic electron flux at GEO and not interplanetary magnetic field connection to Jupiter.

  9. Electron and proton flux models for Jupiter's radiation belts

    NASA Technical Reports Server (NTRS)

    Klopp, D. A.

    1972-01-01

    Estimates of the energetic particle distribution in Jupiter's radiation belts are presented and are compared with previous estimates. Mathematical expressions are developed for the equatorial electron and proton fluxes, shielded electron and proton dose rates, and radiation lifetimes of electronic circuits. It is calculated that a 1 g/sq cm aluminum shield will screen out all protons of energy less than 27.5 MeV, and a 2 g/sq cm shield will screen out protons less than 40.6 MeV. The radiation lifetimes are based on a maximum permissible dose value of 10 million rads, a value 1/2 to 1/3 of the flux at which electronic circuits begin to fail. Estimated increases in lifetimes by using a 3 x 50 orbit instead of a 3 x 3 orbit, and going from 1 to 2 g/sq cm are given.

  10. Natural and artificially injected electron fluxes near discrete auroral arcs

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.

    1980-01-01

    A sounding rocket payload instrumented in order to inject and observe energetic electron fluxes in the ionospheric plasma was flown from Ft. Churchill into a bright auroral display on 9 April 1978. Measurements of one throw-away detector in three energy channels at 1.9, 4 and 8 keV are discussed in order to relate the observed electron echoes to the prevailing geophysical conditions.

  11. Measurement of neutrino flux from neutrino-electron elastic scattering

    NASA Astrophysics Data System (ADS)

    Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.; Miner ν A Collaboration

    2016-06-01

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ˜10 % due to uncertainties in hadron production and focusing. We have isolated a sample of 135 ±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.

  12. Measurement of neutrino flux from neutrino-electron elastic scattering

    SciTech Connect

    Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman,; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.

    2016-06-10

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.

  13. Measurement of neutrino flux from neutrino-electron elastic scattering

    SciTech Connect

    Park, J.; Aliaga, L.; Altinok, O.; Bellantoni, L.; Bercellie, A.; Betancourt, M.; Bodek, A.; Bravar, A.; Budd, H.; Cai, T.; Carneiro, M. F.; Christy, M. E.; Chvojka, J.; da Motta, H.; Dytman, S. A.; Díaz, G. A.; Eberly, B.; Felix, J.; Fields, L.; Fine, R.; Gago, A. M.; Galindo, R.; Ghosh, A.; Golan, T.; Gran, R.; Harris, D. A.; Higuera, A.; Kleykamp, J.; Kordosky, M.; Le, T.; Maher, E.; Manly, S.; Mann, W. A.; Marshall, C. M.; Martinez Caicedo, D. A.; McFarland, K. S.; McGivern, C. L.; McGowan, A. M.; Messerly, B.; Miller, J.; Mislivec, A.; Morfín, J. G.; Mousseau, J.; Naples, D.; Nelson, J. K.; Norrick, A.; Nuruzzaman,; Osta, J.; Paolone, V.; Patrick, C. E.; Perdue, G. N.; Rakotondravohitra, L.; Ramirez, M. A.; Ray, H.; Ren, L.; Rimal, D.; Rodrigues, P. A.; Ruterbories, D.; Schellman, H.; Solano Salinas, C. J.; Tagg, N.; Tice, B. G.; Valencia, E.; Walton, T.; Wolcott, J.; Wospakrik, M.; Zavala, G.; Zhang, D.

    2016-06-10

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.

  14. Measurement of neutrino flux from neutrino-electron elastic scattering

    DOE PAGES

    Park, J.; Aliaga, L.; Altinok, O.; ...

    2016-06-10

    Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently, a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ~10% due to uncertainties in hadron production and focusing. We also isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9%more » to 6%. Finally, our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies.« less

  15. Collisionality scaling of the electron heat flux in ETG turbulence

    NASA Astrophysics Data System (ADS)

    Colyer, G. J.; Schekochihin, A. A.; Parra, F. I.; Roach, C. M.; Barnes, M. A.; Ghim, Y.-c.; Dorland, W.

    2017-05-01

    In electrostatic simulations of MAST plasma at electron-gyroradius scales, using the local flux-tube gyrokinetic code GS2 with adiabatic ions, we find that the long-time saturated electron heat flux (the level most relevant to energy transport) decreases as the electron collisionality decreases. At early simulation times, the heat flux ‘quasi-saturates’ without any strong dependence on collisionality, and with the turbulence dominated by streamer-like radially elongated structures. However, the zonal fluctuation component continues to grow slowly until much later times, eventually leading to a new saturated state dominated by zonal modes and with the heat flux proportional to the collision rate, in approximate agreement with the experimentally observed collisionality scaling of the energy confinement in MAST. We outline an explanation of this effect based on a model of ETG turbulence dominated by zonal-nonzonal interactions and on an analytically derived scaling of the zonal-mode damping rate with the electron-ion collisionality. Improved energy confinement with decreasing collisionality is favourable towards the performance of future, hotter devices.

  16. Hamiltonian magnetic reconnection with parallel electron heat flux dynamics

    NASA Astrophysics Data System (ADS)

    Grasso, D.; Tassi, E.

    2015-10-01

    > We analyse, both analytically and numerically, a two-dimensional six-field fluid model for collisionless magnetic reconnection, accounting for temperature and heat flux fluctuations along the direction of the magnetic guide field. We show that the model possesses a Hamiltonian structure with a non-canonical Poisson bracket. This bracket is characterized by the presence of six infinite families of Casimirs, associated with Lagrangian invariants. This reveals that the model can be reformulated as a system of advection equations, thus generalizing previous results obtained for Hamiltonian isothermal fluid models for reconnection. Numerical simulations indicate that the presence of heat flux and temperature fluctuations yields slightly larger growth rates and similar saturated island amplitudes, with respect to the isothermal models. For values of the sonic Larmor radius much smaller than the electron skin depth, heat flux fluctuations tend to be suppressed and temperature fluctuations follow density fluctuations. Increasing the sonic Larmor radius results in an increasing fraction of magnetic energy converted into heat flux, at the expense of temperature fluctuations. In particular, heat flux fluctuations tend to become relevant along the magnetic island separatrices. The qualitative structures associated with the electron field variables are also reinterpreted in terms of the rotation of the Lagrangian invariants of the system.

  17. Geosynchronous Electron Fluxes and Chorus Generation During an MHD Substorm

    NASA Astrophysics Data System (ADS)

    Woodroffe, J. R.; Jordanova, V.; Henderson, M. G.; Welling, D. T.; Vernon, L.

    2015-12-01

    We present results from a numerical study of electron dynamics and whistler generation during an idealized substorm simulated using the Space Weather Modeling Framework. The time-dependent electric and magnetic fields from this simulated substorm are used to drive a new backwards particle tracing model, and the results from this model are used to identify the regions responsible for populating geosynchronous orbit during and after the substorm. Liouville mapping is then used to obtain electron fluxes at geosynchronous orbit as well as to assess the development of anisotropy during the earthward propagation of the electron injection.

  18. Ion and electron velocity distributions within flux transfer events

    NASA Technical Reports Server (NTRS)

    Thomsen, M. F.; Stansberry, J. A.; Bame, S. J.; Fuselier, S. A.; Gosling, J. T.

    1987-01-01

    The detailed nature of the thermal and suprathermal ion and electron distributions within magnetic flux transfer events (FTEs) is examined. Examples of both magnetosheath FTEs and magnetospheric FTEs are discussed. The detailed distributions confirm that FTEs contain a mixture of magnetosheath and magnetospheric plasmas. To lowest order, the distributions are consistent with a simple superposition of the two interpenetrating populations, with no strong interactions between them. To first order, some interesting differences appear, especially in the electron distributions, suggesting that considerable pitch angle scattering and some electron energy diffusion are also occurring. These observations should provide a useful test of analytical and numerical studies of interpenetrating plasmas.

  19. Observational constraints on relativistic electron dynamics: temporal evolution of electron spectra and flux isotropization

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Selesnick, R. S.; Baker, D. N.; Blake, J. B.

    2007-05-01

    Models of energization of electrons in the Earth's outer radiation belts invoke two classes of processes, radial transport and in-situ wave-particle interactions. Temporal evolution of electron spectra and flux isotropization during energization events provide useful observational constraints on models of electron energization. Events dominated by radial diffusion result in pancake type pitch angle distributions whereas some in-situ wave-particle energization mechanisms include pitch angle scattering leading to rapid flux isotropization. We present a survey of flux isotrpization time scales and electron spectra during relativstic electron enhancement events. We will use data collected by detectors onboard SAMPEX in low earth orbit and Polar which measures electron fluxes at higher altitude to measure flux isotropization. Electron spectra are obtained by pulse height analyzed data from the PET detector onboard SAMPEX.SAMPEX measurements cover the entire outer zone for more than a decade from mid 1992 to mid 2004 and Polar covers the time period from mid 1996 to the present.

  20. Electron Heat Flux in Pressure Balance Structures at Ulysses

    NASA Technical Reports Server (NTRS)

    Yamauchi, Yohei; Suess, Steven T.; Sakurai, Takashi; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Pressure balance structures (PBSs) are a common feature in the high-latitude solar wind near solar minimum. Rom previous studies, PBSs are believed to be remnants of coronal plumes and be related to network activity such as magnetic reconnection in the photosphere. We investigated the magnetic structures of the PBSs, applying a minimum variance analysis to Ulysses/Magnetometer data. At 2001 AGU Spring meeting, we reported that PBSs have structures like current sheets or plasmoids, and suggested that they are associated with network activity at the base of polar plumes. In this paper, we have analyzed high-energy electron data at Ulysses/SWOOPS to see whether bi-directional electron flow exists and confirm the conclusions more precisely. As a result, although most events show a typical flux directed away from the Sun, we have obtained evidence that some PBSs show bi-directional electron flux and others show an isotropic distribution of electron pitch angles. The evidence shows that plasmoids are flowing away from the Sun, changing their flow direction dynamically in a way not caused by Alfven waves. From this, we have concluded that PBSs are generated due to network activity at the base of polar plumes and their magnetic structures axe current sheets or plasmoids.

  1. Characteristics of heat flux and electromagnetic electron-cyclotron instabilities driven by solar wind electrons

    NASA Astrophysics Data System (ADS)

    Saeed, Sundas; Sarfraz, M.; Yoon, P. H.; Qureshi, M. N. S.

    2017-01-01

    In-situ observations reveal the existence of electron velocity distribution function in the solar wind, where the net distribution can be modeled by a combination of core, halo and strahl. These components often possess a relative drift and with respective temperature anisotropies. The relative drift between the core and halo components leads to heat flux (HF) instability, while temperature anisotropies drive electromagnetic electron-cyclotron (EMEC) instability. These instabilities have been separately studied in the literature, but for the first time, the present study combines both unstable modes in the presence of two free energy sources, namely, excessive parallel pressure and excessive perpendicular temperature. Heat flux instability (which is a left-hand circularly polarized mode) is effectively similar to electron firehose instability, except that the free energy is provided by net relative drift among two component electrons in the background of protons. The heat flux instability is discussed here along with (the right-hand polarized) EMEC instability driven by temperature anisotropy. The unstable heat flux mode is conventionally termed the "whistler" heat flux instability, but it is actually polarized in the opposite sense to the whistler wave. Electromagnetic electron-cyclotron mode, on the other hand, reduces to the proper whistler wave in the absence of free energy source. The present combined analysis clarifies the polarization characteristics of these two modes in an unambiguous manner.

  2. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    PubMed

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc.

  3. Automatic solar image motion measurements. [electronic disk flux monitoring

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.; Moore, E. P.

    1975-01-01

    The solar seeing image motion has been monitored electronically and absolutely with a 25 cm telescope at three sites along the ridge at the southern end of the Magdalena Mountains west of Socorro, New Mexico. The uncorrelated component of the variations of the optical flux from two points at opposite limbs of the solar disk was continually monitored in 3 frequencies centered at 0.3, 3 and 30 Hz. The frequency band of maximum signal centered at 3 Hz showed the average absolute value of image motion to be somewhat less than 2sec. The observer estimates of combined blurring and image motion were well correlated with electronically measured image motion, but the observer estimates gave a factor 2 larger value.

  4. Polar cap auroral electron fluxes observed with Isis 1

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.

    1974-01-01

    Three types of auroral particle precipitation have been observed over the polar caps, well inside the auroral oval, by means of the soft particle spectrometer on the Isis 1 satellite. The first type is a uniform, very soft (about 100 eV) electron 'polar rain' over the entire polar cap; this may well be present with very weak intensity at all times, but it is markedly enhanced during worldwide geomagnetic storms. A second type of precipitation is a structured flux of electrons with energies near 1 keV, suggestive of localized 'polar showers'; it seems likely that these are the cause of the sun-aligned auroral arcs that have been observed during moderately quiet conditions. During periods of intense magnetic disturbance this precipitation can become very intense and exhibit a characteristic pattern that we have come to call a 'polar squall'.

  5. Polar cap auroral electron fluxes observed with Isis 1

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.

    1974-01-01

    Three types of auroral particle precipitation have been observed over the polar caps, well inside the auroral oval, by means of the soft particle spectrometer on the Isis 1 satellite. The first type is a uniform, very soft (about 100 eV) electron 'polar rain' over the entire polar cap; this may well be present with very weak intensity at all times, but it is markedly enhanced during worldwide geomagnetic storms. A second type of precipitation is a structured flux of electrons with energies near 1 keV, suggestive of localized 'polar showers'; it seems likely that these are the cause of the sun-aligned auroral arcs that have been observed during moderately quiet conditions. During periods of intense magnetic disturbance this precipitation can become very intense and exhibit a characteristic pattern that we have come to call a 'polar squall'.

  6. Electron flux models for different energies at geostationary orbit

    NASA Astrophysics Data System (ADS)

    Boynton, R. J.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Billings, S. A.; Ganushkina, N.

    2016-10-01

    Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

  7. Electron Flux Models for Different Energies at Geostationary Orbit

    NASA Technical Reports Server (NTRS)

    Boynton, R. J.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Billings, S. A.; Ganushkina, N.

    2016-01-01

    Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

  8. Counterstreaming electrons in small interplanetary magnetic flux ropes

    NASA Astrophysics Data System (ADS)

    Feng, H. Q.; Zhao, G. Q.; Wang, J. M.

    2015-12-01

    Small interplanetary magnetic flux ropes (SIMFRs) are commonly observed by spacecraft at 1 AU, and their origin still remains disputed. We investigated the counterstreaming suprathermal electron (CSE) signatures of 106 SIMFRs measured by Wind during 1995-2005. We found that 79 (75%) of the 106 flux ropes contain CSEs, and the percentages of counterstreaming vary from 8% to 98%, with a mean value of 51%. CSEs are often observed in magnetic clouds (MCs), and this indicates these MCs are still attached to the Sun at both ends. CSEs are also related to heliospheric current sheets (HCSs) and the Earth's bow shock. We divided the SIMFRs into two categories: The first category is far from HCSs, and the second category is in the vicinity of HCSs. The first category has 57 SIMFRs, and only 7 of 57 ropes have no CSEs. This ratio is similar to that of MCs. The second category has 49 SIMFRs; however, 20 of the 49 events have no CSEs. This ratio is larger than that of MCs. These two categories have different origins. One category originates from the solar corona, and most ropes are still connected to the Sun at both ends. The other category is formed near HCSs in the interplanetary space.

  9. Localized electrons on a lattice with incommensurate magnetic flux

    NASA Astrophysics Data System (ADS)

    Fishman, Shmuel; Shapir, Yonathan; Wang, Xiang-Rong

    1992-11-01

    The magnetic-field effects on lattice wave functions of Hofstadter electrons strongly localized at boundaries are studied analytically and numerically. The exponential decay of the wave function is modulated by a field-dependent amplitude J(t)=tprodt-1r=02 cos(παr), where α is the magnetic flux per plaquette (in units of a flux quantum) and t is the distance from the boundary (in units of the lattice spacing). The behavior of ||J(t)|| is found to depend sensitively on the value of α. While for rational values α=p/q the envelope of J(t) increases as 2t/q, the behavior for α irrational (q-->∞) is erratic with an aperiodic structure which drastically changes with α. For algebraic α it is found that J(t) increases as a power law tβ(α) while it grows faster (presumably as tβ(α)lnt) for transcendental α. This is very different from the growth rate J(t)~e√t that is typical for cosines with random phases. The theoretical analysis is extended to products of the type Jν(t)=tprodt-1r=02 cos(παrν) with ν>0. Different behavior of Jν(t) is found in various regimes of ν. It changes from periodic for small ν to randomlike for large ν.

  10. Extreme relativistic electron fluxes at geosynchronous orbit: Analysis of GOES E > 2 MeV electrons

    NASA Astrophysics Data System (ADS)

    Meredith, Nigel P.; Horne, Richard B.; Isles, John D.; Rodriguez, Juan V.

    2015-03-01

    Relativistic electrons (E > 1 MeV) cause internal charging on satellites and are an important space weather hazard. A key requirement in space weather research concerns extreme events and knowledge of the largest flux expected to be encountered over the lifetime of a satellite mission. This is interesting both from scientific and practical points of view since satellite operators, engineers, and the insurance industry need this information to better evaluate the effects of extreme events on their spacecraft. Here we conduct an extreme value analysis of daily averaged E > 2 MeV electron fluxes from the Geostationary Operational Environmental Satellites (GOES) during the 19.5 year period from 1 January 1995 to 30 June 2014. We find that the daily averaged flux measured at GOES West is typically a factor of about 2.5 higher than that measured at GOES East, and we conduct independent analyses for these two locations. The 1 in 10, 1 in 50, and 1 in 100 year daily averaged E > 2 MeV electron fluxes at GOES West are 1.84 ×105, 5.00 ×105, and 7.68 ×105 cm-2 s-1 sr-1, respectively. The corresponding fluxes at GOES East are 6.53 ×104, 1.98 ×105, and 3.25 ×105 cm-2 s-1 sr-1, respectively. The largest fluxes seen during the 19.5 year period on 29 July 2004 were particularly extreme and were seen by satellites at GOES West and GOES East. The extreme value analysis suggests that this event was a 1 in 50 year event.

  11. In Situ Measurement of Energetic Electron Fluxes Inside Thunderclouds

    NASA Astrophysics Data System (ADS)

    Arabshahi, S.; Vodopiyanov, I. B.; Dwyer, J. R.; Rassoul, H.

    2013-12-01

    It is now well established that high-energy radiation is routinely produced by thunderclouds and lightning. This radiation is in the form of x-rays and gamma-rays with timescales ranging from sub-microsecond (x-rays associated with lightning leaders), to sub-millisecond (Terrestrial Gamma-ray Flashes), to minute long glows (Gamma-ray Glows from thunderclouds seen on the ground and in or near the cloud by aircrafts and balloons). It is generally accepted that these emissions originate from bremsstrahlung interactions of relativistic runaway electrons with air, which can be accelerated in the thundercloud/lightning electric fields and gain up to multi-MeV energies. However, the exact physical details of the mechanism that produces these runaway electrons are still unknown. In order to better understand the source of energetic radiation inside thunderclouds, we have begun a campaign of balloon-borne instruments to directly measure the flux of energetic electrons inside thunderclouds. In the current configuration, each balloon carries Geiger counters to record the energetic particles. Geiger counters are well suited for directly measuring energetic electrons and positrons and have the advantage of being lightweight and dependable. Due to the nature of the thunderstorm environment, the campaign has many design, communication, and safety challenges. In this presentation we will report on the status of the campaign and some of the physical insights gained from the data collected by our instruments. This work was supported in part by the NASA grant NNX12A002H and by DARPA grant HR0011-1-10-1-0061.

  12. Balloon-borne measurement of energetic electron fluxes inside thunderclouds

    NASA Astrophysics Data System (ADS)

    Arabshahi, Shahab; Vodopiyanov, Igor; Dwyer, Joseph; Rassoul, Hamid

    2014-05-01

    High-energy radiation is routinely produced by thunderclouds and lightning. This radiation is in the form of x-rays and gamma-rays with timescales ranging from sub-microsecond (x-rays associated with lightning leaders), to sub-millisecond (Terrestrial Gamma-ray Flashes), to minute long glows (Gamma-ray Glows from thunderclouds seen on the ground and in or near the cloud by aircrafts and balloons). It is generally accepted that these emissions originate from bremsstrahlung interactions of relativistic runaway electrons with air, which can be accelerated in the thundercloud/lightning electric fields and gain up to multi-MeV energies. However, the exact physical details of the mechanism that produces these runaway electrons are still unknown. In order to better understand the source of energetic radiation inside thunderclouds, we have begun a campaign of balloon-borne instruments to directly measure the flux of energetic electrons inside thunderclouds. In the current configuration, each balloon carries Geiger counters to record the energetic particles. Geiger counters are well suited for directly measuring energetic electrons and positrons and have the advantage of being lightweight and dependable. We transmit data at 900MHz, ISM band, with 115.2 kb/s transmission rate. This would provide us a high resolution radiation profile over a relatively large distance. Due to the nature of the thunderstorm environment, the campaign has many design, communication, and safety challenges. In this presentation we will report on the status of the campaign and some of the physical insights gained from the data collected by our instruments. This work was supported in part by the NASA grant NNX12A002H and by DARPA grant HR0011-1-10-1-0061.

  13. Beta electron fluxes inside a magnetic plasma cavern: Calculation and comparison with experiment

    NASA Astrophysics Data System (ADS)

    Stupitskii, E. L.; Smirnov, E. V.; Kulikova, N. A.

    2010-12-01

    We study the possibility of electrostatic blanking of beta electrons in the expanding spherical blob of a radioactive plasma in a rarefied ionosphere. From numerical studies on the dynamics of beta electrons departing a cavern, we obtain the form of a function that determines the portion of departing electrons and calculate the flux density of beta electrons inside the cavern in relation to the Starfish Prime nuclear blast. We show that the flux density of electrons in geomagnetic flux tubes and inside the cavern depend on a correct allowance for the quantity of beta electrons returning to the cavern. On the basis of a physical analysis, we determine the approximate criterion for the return of electrons from a geomagnetic flux tube to the cavern. We compare calculation results in terms of the flux density of beta electrons inside the cavern with the recently published experimental results from operation Starfish Prime.

  14. Critical heat flux investigations for fusion-relevant conditions with the use of a rastered electron beam apparatus

    SciTech Connect

    Koski, J.A.; Croessmann, C.D.

    1988-01-01

    With the use of a rastered electron beam apparatus, investigations of critical heat flux (CH) and associated noise, pressure and flow spectra have been completed for water-cooled test targets under conditions relevant to the design of high-heat-flux components for fusion energy applications. Targets tested were copper tubes with attached graphite armor tiles. Water flows with velocities ranging from 3 to 10 m/s were used, with axially uniform heat fluxes ranging from 10 to 60 MW/m/sup 2/ applied along only one side of the tube to simulate the heating pattern often encountered by plasma facing components in fusion applications. Targets included stainless steel twisted tapes mechanically locked into the tube bore to increase CH levels. Exit conditions typical of highly subcooled flow boiling were considered, e.g., exit qualities of about /minus/0.3, with exit pressures near 1 MPa, and exit temperatures in the 30 to 40 C range. Besides observation of CHF and the comparison to CHF correlations, the studies also examined possible means for predicting and preventing tube burnout. Diagnostics tried included acoustic amplitude and spectra in both the audible and above audible frequency ranges, exit pressure amplitude and spectra, and flow variations and spectra. During testing, signals from the diagnostics showed a large increase in amplitude before CHF occurred. 13 refs., 9 figs.

  15. A survey of superthermal electron flux depressions, or "electron holes," within the illuminated Martian induced magnetosphere

    NASA Astrophysics Data System (ADS)

    Hall, B. E. S.; Lester, M.; Nichols, J. D.; Sánchez-Cano, B.; Andrews, D. J.; Opgenoorth, H. J.; Fränz, M.

    2016-05-01

    Since Mars lacks a global intrinsic magnetic field, the solar wind interacts directly with the Martian upper atmosphere and ionosphere. The presence of localized intense remnant crustal magnetic fields adds to this interaction, making the Martian plasma system a unique environment within the solar system. Rapid reductions in the electron flux, referred to as "electron holes," occur within the Martian induced magnetosphere (IM). We present a statistical analysis of this phenomenon identified from proxy measurements of the electron flux derived from measurements by the Analyser of Space Plasmas and Energetic Neutral Atoms Electron Spectrometer experiment on board the Mars Express (MEX) spacecraft. The study is completed for the period of 9 February 2004 to 9 May 2014. Electron holes are observed within the IM in more than 56% of MEX orbits during this study period, occurring predominantly at altitudes less than 1300 km, with the majority in the negative X Mars-Centric Solar Orbital direction. The spatial distribution above the surface of Mars is observed to bear close resemblance to that of the crustal magnetic fields as predicted by the Cain et al. magnetic field model, suggesting that they play an important role in the formation of these phenomena.

  16. Plasmaspheric Electron Densities and Plasmashere-Ionosphere Coupling Fluxes

    NASA Astrophysics Data System (ADS)

    Lichtenberger, Janos; Cherneva, Nina; Shevtsov, Boris; Sannikov, Dmitry; Ferencz, Csaba; Koronczay, David

    The Automatic Whistler Detector and Analyzer Network (AWDANet) is able to detect and analyze whistlers in quasi-realtime and can provide equatorial electron density data. The plasmaspheric electron densities and ionosphere-plasmasphere coupling fluxes are key parameters for plasmasphere models in Space Weather related investigations, particularly in modeling charged particle accelerations and losses in Radiation Belts. The global AWDANet [1] detects millions of whistlers in a year. The system has been recently completed with automatic analyzer capability in PLASMON (http://plasmon.elte.hu) project. It is based on a recently developed whistler inversion model [2], that opened the way for an automated process of whistler analysis, not only for single whistler events but for complex analysis of multiple-path propagation whistler groups [3]. In this paper we present the results of quasi-real-time runs processing whistlers from quiet and disturb periods from Karymshina station (Kamchatka, Russia). Refilling rates, that are not yet known in details are also presented for the various periods. 1.Lichtenberger, J., C. Ferencz, L. Bodnár, D. Hamar, and P. Steinbach (2008), Automatic whistler detector and analyzer system: Automatic whistler detector, J. Geophys. Res., 113, A12201, doi:10.1029/2008JA013467. 2. Lichtenberger, J. (2009), A new whistler inversion method, J. Geophys. Res., 114, A07222, doi:10.1029/2008JA013799. 3. Lichtenberger, J., C. Ferencz, D. Hamar, P. Steinbach, C. J. Rodger, M. A. Clilverd, and A. B. Collier (2010), Automatic Whistler Detector and Analyzer system: Implementation of the analyzer algorithm, J. Geophys. Res., 115, A12214, doi:10.1029/2010JA015931.

  17. Comparison between triangulated auroral altitude and precipitating electron energy flux

    NASA Astrophysics Data System (ADS)

    Sangalli, L.; Partamies, N. J.; Gustavsson, B.

    2012-12-01

    The MIRACLE network monitors auroral activity in the Fennoscandian sector of Europe. Network stations cover the range of 55° to 57° magnetic latitude North and span two hours in magnetic local time. Some of the MIRACLE network stations include digital all-sky cameras (ASC) with overlapping field-of-views at the latitude aurora occurs. The ASCs in this network operate at three different wavelengths: 427.8 nm (blue line), 557.7 nm (green line) and 630.0 nm (red line). These wavelengths are selected using narrow band filters. Red and blue lines images are recorded once per minute and green line images every 20 s. On January 31, 2001 multiple discrete arcs were observed at the zenith of the ASC located in Muonio (67.9° N, 23.6° E) and were visible in other stations. The peak auroral emission is estimated using triangulation between pairs of stations and compared with precipitating electron energy fluxes inverted from ASC images and measured in situ on the DMSP satellite.

  18. Comparison between triangulated auroral altitude and precipitating electron energy flux

    NASA Astrophysics Data System (ADS)

    Sangalli, L.; Partamies, N. J.; Gustavsson, B.

    2013-12-01

    The MIRACLE network monitors auroral activity in the Fennoscandian sector of Europe. Network stations cover the range of 55° to 57° magnetic latitude North and span two hours in magnetic local time. Some of the MIRACLE network stations include digital all-sky cameras (ASC) with overlapping field-of-views at the latitude aurora occurs. The ASCs in this network operate at three different wavelengths: 427.8 nm (blue line), 557.7 nm (green line) and 630.0 nm (red line). These wavelengths are selected using narrow band filters. Red and blue lines images are recorded once per minute and green line images every 20 s. On January 31, 2001 multiple discrete arcs were observed at the zenith of the ASC located in Muonio (67.9° N, 23.6° E) and were visible in other stations. The peak auroral emission is estimated using triangulation between pairs of stations and compared with precipitating electron energy fluxes inverted from ASC images and measured in situ on the DMSP satellite.

  19. Identifying Loss Mechanisms Responsible for the Rapid Depletion of Outer Radiation Belt Electron Flux

    NASA Astrophysics Data System (ADS)

    Green, J. C.; Onsager, T. G.; O'Brien, T.; Fraser, B. J.

    2004-12-01

    Since the discovery of earth's radiation belts researchers have sought to explain and predict the changing relativistic electron flux levels in the outer belt. This goal has proved a perplexing challenge because, surprisingly, flux levels do not always rise as energy input from the solar wind increases during active periods such as geomagnetic storms [Reeves et al., 2003;O'Brien et al., 2001]. The erratic response of the radiation belt electrons to geomagnetic activity suggests that flux levels are set by a teetering struggle between acceleration and loss. Thus, to predict flux variations, both processes must be understood. Some acceleration mechanisms have been proposed and tested resulting in incremental progress, but still little is known about how relativistic electrons are removed from the magnetosphere. We investigate how relativistic electrons are lost from the outer radiation belt using a superposed epoch analysis of electron flux decrease events identified in multi-satellite data [Onsager et al., 2002; Green et al., 2004]. More specifically, we test three mechanisms proposed to explain the flux reductions: adiabatic motion in response to a changing magnetic field topology, drift out the magnetopause boundary, and scattering into the atmosphere. The superposed study shows that the magnetic field becomes temporarily stretched at dusk suggesting that adiabatic electron motion might contribute to the initial flux reduction; however, the electron flux does not recover when the magnetic field recovers, indicating that true loss from the magnetosphere occurs. Magnetopause encounters should similarly affect both high energy protons and electrons; however, no concurrent reduction of proton flux is observed implying that this mechanism is not active. Low altitude observations show increased electron flux in the loss cone suggesting that scattering to the atmosphere is the cause the flux depletions. We investigate possible causes of the increased scattering including

  20. Auroral electron precipitation and flux tube erosion in Titan’s upper atmosphere

    NASA Astrophysics Data System (ADS)

    Snowden, D.; Yelle, R. V.; Galand, M.; Coates, A. J.; Wellbrock, A.; Jones, G. H.; Lavvas, P.

    2013-09-01

    Cassini dasta shows that Titan’s atmosphere strongly depletes the electron content in Saturn’s flux tubes, producing features known as electron bite-outs, which indicate that the flux of auroral electrons decreases over time. To understand this process we have developed a time-dependent two-stream model, which uses field line geometries and drift paths calculated by a three-dimensional multi-fluid model of Titan’s plasma interaction. The boundary conditions of the model account for the time-dependent reduction or increase in electron flux along Saturn’s magnetic field lines because of the loss or production of electrons in Titan’s atmosphere. The modification of the auroral electron flux depends on the electron bounce period in Saturn’s outer magnetosphere; therefore, we also calculate electron bounce periods along several Kronian field lines accounting for both the magnetic mirroring force and the field-aligned electric potential in Saturn’s plasma sheet. We use the time-dependent two-stream model to calculate how the reduction in the auroral electron flux affects electron impact ionization and energy deposition rates in Titan’s upper atmosphere. We find that the flux of higher energy (>50 eV) electrons entering Titan’s atmosphere is strongly reduced over time, resulting in smaller ionization and energy deposition rates below ∼1300 km altitude. Finally, we show that sample spectrograms produced from our calculations are consistent with CAPS-ELS data.

  1. Sawtooth oscillations in the flux of runaway electrons to the PLT limiter

    SciTech Connect

    Barnes, C.W.; Strachan, J.D.

    1982-03-01

    Increased fluxes of runaway electrons at the PLT limiter are observed in the few milliseconds following internal disruptions. These fluxes have an inverted (outside) sawtooth character. The time for the flux to reach a maximum after the disruption has been studied as a function of the plasma parameters for thousands of PLT discharges. One interpretation is that this delay represents the time for a perturbation to the runaway electron population to travel from the q = 1 region to the plasma boundary. These times are approx. 10/sup -1/ of the electron thermal confinement times and increase with the plasma electron density.

  2. Nightside electron flux measurements at Mars by the Phobos-2 HARP instrument

    NASA Technical Reports Server (NTRS)

    Shutte, N.; Gringauz, K.; Kiraly, P.; Kotova, G.; Nagy, A. F.; Rosenbauer, H.; Szego, K.; Verigin, M.

    1995-01-01

    All the available nightside electron data obtained during circular orbits at Mars from the Phobos-2 Hyperbolic Retarded Potential Analyzer (HARP) instrument have been examined in detail and are summarized in this paper. An electron flux component with energies exceeding that of the unperturbed solar wind was observed inside the magnetosheath, indicating the presence of acceleration mechanism(s). The character of the electron fluxes measured in the magnetotail cannot be classified in any simple manner, however, there is a correlation between the electron fluxes measured well inside this region and the unperturbed solar wind ram pressure.

  3. Selective four electron reduction of O2 by an iron porphyrin electrocatalyst under fast and slow electron fluxes.

    PubMed

    Samanta, Subhra; Sengupta, Kushal; Mittra, Kaustuv; Bandyopadhyay, Sabyasachi; Dey, Abhishek

    2012-08-07

    An iron porphyrin catalyst with four electron donor groups is reported. The porphyrin ligand bears a distal hydrogen bonding pocket which inverts the normal axial ligand binding selectivity exhibited by porphyrins bearing sterically crowded distal structures. This catalyst specifically reduces O(2) by four electrons under both fast and slow electron fluxes at pH 7.

  4. Energetic electron spectra and flux isotropization during different phases of solar cycle

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Selesnick, R. S.; Baker, D. N.; Blake, J. B.

    2006-12-01

    We will report here on the measurements of electron spectra and flux isotropization during electron energization events. We will present the results of investigating the dependence of electron spectra and flux isotropization upon solar cycle phase. It is well known that high speed solar wind streams dominate during the descending phase of the solar cycle whereas coronal mass ejections are the dominant driver of the magnetosphere during the ascending phase. Temporal evolution of electron spectra and flux isotropization may be important discriminators of models of electron energization in the Earth's outer zone. For example, radial diffusion preferentially energizes electrons of large equatorial pitch angles whereas some in-situ wave-particle energization mechanisms include concomittant pitch angle scattering leading to rapid flux isotropization. The systematics of electron energization due to different drivers may shed light upon the underlying physical processes. We will use data collected by detectors onboard SAMPEX in low earth orbit and Polar which measures electron fluxes at higher altitude to characterize flux isotropization. Electron spectra are obtained by the use of pulse height analyzed data from the PET detector onboard SAMPEX. We will use global field models such as the Tsyaganenko-04 model, to calculate thegeneralized L parameter during geomagnetically disturbed times. SAMPEX measurements cover the entire outer zone for more than a decade from mid 1992 to mid 2004 and Polar covers the time period from mid 1996 to the present.

  5. Influence of the crustal magnetic field on the Mars aurora electron flux and UV brightness

    NASA Astrophysics Data System (ADS)

    Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.; Hubert, B.

    2017-01-01

    Observations with the SPICAM instrument on board Mars Express have shown the occasional presence of localized ultraviolet nightside emissions associated with enhanced energetic electron fluxes. These features generally occur in regions with significant radial crustal magnetic field. We use a Monte-Carlo electron transport model to investigate the role of the magnetic field on the downward and upward electron fluxes, the brightness and the emitted power of auroral emissions. Simulations based on an ASPERA-3 measured auroral electron precipitation indicate that magnetic mirroring leads to an intensification of the energy flux carried by upward moving electrons- from about 20% in the absence of crustal magnetic field up to 33-78% when magnetic field is included depending on magnetic field topology. Conservation of the particle flux in a flux tube implies that the presence of the B-field does not appreciably modify the emission rate profiles for an initially isotropic pitch angle distribution. However, we find that crustal magnetic field results in increase of the upward electron flux, and, consequently, in reduction of the total auroral brightness for given energy flux of precipitating electrons.

  6. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    DOE PAGES

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; ...

    2015-12-22

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraftmore » were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the KP index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.« less

  7. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-01

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. To provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Model explanatory parameters were selected from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L ≧ 4.8 and L ≧ 5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≦ L ≦ 6, while for the GEO flux prediction, the KP index is better than Dst. A test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  8. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    SciTech Connect

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-22

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the KP index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  9. Characteristics of heat flux and electromagnetic electron-cyclotron instabilities driven by solar wind electrons

    NASA Astrophysics Data System (ADS)

    Saeed, Sundas; Yoon, P. H.; Sarfraz, M.; Qureshi, M. N. S.

    2017-04-01

    In situ observations reveal the existence of electron velocity distribution function in the solar wind, where the net distribution can be modelled by a combination of core, halo and strahl. These components often possess a relative drift and with respective temperature anisotropies. The relative drift between the core and halo components leads to heat flux (HF) instability, while temperature anisotropies drive electromagnetic electron-cyclotron (EMEC) instability. These instabilities have been separately studied in the literature, but for the first time, the present study combines both unstable modes in the presence of two free energy sources, namely, excessive parallel pressure and excessive perpendicular temperature. HF instability (which is a left-hand circularly polarized mode) is effectively similar to electron firehose instability, except that the free energy is provided by net relative drift among two component electrons in the background of protons. The HF instability is discussed here along with (the right-hand polarized) EMEC instability driven by temperature anisotropy. The unstable HF mode is conventionally termed the 'whistler' HF instability, but it is actually polarized in the opposite sense to the whistler wave. EMEC mode, on the other hand, reduces to the proper whistler wave in the absence of free energy source. The present combined analysis clarifies the polarization characteristics of these two modes in an unambiguous manner.

  10. Regulation of the solar wind electron heat flux from 1 to 5 AU: Ulysses observations

    SciTech Connect

    Scime, E.E.; Bame, S.J.; Feldman, W.C.; Gary, S.P.; Phillips, J.L.; Balogh, A.

    1994-12-01

    In this study the authors use observations from the three-dimensional electron spectrometer and magnetometer aboard the Ulysses spacecraft to examine the solar wind electron heat flux from 1.2 to 5.4 AU in the ecliptic plane. Throughout Ulysses` transit to 5.4 AU, the electron heat flux decreases more rapidly ({approximately}R{sup {minus}3.0}) than simple collisionless expansion along the local magnetic field and is smaller than expected for a thermal gradient heat flux, q{sub {parallel}}e(r)={minus}k{sub {parallel}}{del}{sub {parallel}}T{sub e}(r). The radial gradients and magnitudes expected for a number of electron heat flux regulatory mechanisms are examined and compared to the observations. The best agreement is found for heat flux regulation by the whistler heat flux instability. The upper bound and radial scaling for the electron heat flux predicted for the whistler heat flux instability are consistent with observations.

  11. Searching for Dark Matter Signatures in the GLAST LAT Electron Flux

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander; Profumo, Stefano

    2008-01-01

    We explored several viable scenarios of how LAT might observe DM, when the spectral feature is predicted to be observed in the HE electron flux It has been demonstrated elsewhere that LAT will be capable to detect HE electrons flux in energy range from 20 GeV to - 1 TeV with 520% energy resolution and good statistics If there is a DM-caused feature in the HE electron flux (in the range 20 GeV - 1 TeV), LAT will be the best current instrument to observe it!

  12. Relativistic electron losses by microbursts and their relationship to flux decay time scales

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; Fennell, J. F.; Klecker, B.

    2011-12-01

    Rapid fluctuations of electron fluxes on timescales of milliseconds have long been observed and have recently drawn attention as a major process of loss of relativistic electrons from the Earth's outer radiation belts. Studies suggest that recently observed large-amplitude whistler wave packets may be closely associated with electron precipitation microbursts.We study relativistic electron losses in the outer radiation belts by characterizing decay timescales at low altitudes and investigate their relationship to microbursts. We use data collected by SAMPEX, a low-Earth orbiting spacecraft in a highly inclined polar orbit to characterize electron flux decay timescales. The LICA,HILT and PET sensors onboard SAMPEX measure electrons in various integral and differential channels. Using high resolution measurements made by the HILT sensor we identify and quantify electron microburst characteristics. We report here on our investigations of the interconnection between flux decay times and microbursts both using case studies and on a statistical basis.

  13. Fast tokamak plasma flux and electron density reconstruction technique

    SciTech Connect

    Chiang, K.L.; Hallock, G.A.; Wootton, A.J.; Wang, L.

    1997-01-01

    Density profiles in TEXT-U are obtained using a vertical viewing far-infrared (FIR) interferometer. To obtain the local (inverted) density, we have developed a simple analytic model of the plasma equilibrium configuration which is faster than EFIT (a flux surface reconstruction program) and can be easily computed between discharges. This analytic solution of the Grad{endash}Shafranov equation is valid as long as the pressure p is a function of poloidal flux {psi}, i.e., p=p({psi}). The procedure incorporates both magnetic and FIR density data to solve the Grad{endash}Shafranov equation, and provides a density profile which is self-consistent with the reconstructed equilibrium flux surfaces. Examples are presented. {copyright} {ital 1997 American Institute of Physics.}

  14. Electronic delocalization and persistent currents in nonsymmetric-dimer mesoscopic rings threaded by magnetic flux

    NASA Astrophysics Data System (ADS)

    Hu, X. F.; Peng, Z. H.; Peng, R. W.; Liu, Y. M.; Qiu, F.; Huang, X. Q.; Hu, A.; Jiang, S. S.

    2004-06-01

    We investigate electronic delocalization and magnetic-flux-induced persistent current in the mesoscopic ring, which is constructed according to the nonsymmetric-dimer (NSD) model. The flux-dependent energy spectra, electronic wavefunctions, and persistent currents are theoretically obtained. It is demonstrated that due to the localization-delocalization transition of electrons, the electronic state in the NSD ring can be localized, extended, and the intermediate case between extended states and localized ones. The persistent current (PC) approaches the behavior of free electrons if the Fermi level is around the near-resonant energy. Otherwise, the PC is depressed dramatically. This conclusion could be generalized to other correlated-disordered systems.

  15. Unfolding The High Energy Electron Flux From CRRES Fluxmeter Measurements.

    DTIC Science & Technology

    1996-12-01

    process. The algorithm used by the Fortran 90 code is Jacobi iteration. The Jacobi method iterates to solve a linear system of the form Ax = B. (2-24...The Jacobi method requires an initial estimate of the flux, <pmitial, the subroutine uses Dŕ • yM. Iterations continue until the difference between...c = MatMul(Dinv,b) x = c ! Starting guess ! This is the loop which actually computes the values of the ! unfolded fluxes by using the Jacobi method . See

  16. Neutral hydrogen flux measured at 100- to 200-km altitude in an electron aurora

    NASA Technical Reports Server (NTRS)

    Iglesias, G. E.; Anderson, H. R.

    1975-01-01

    Neutral hydrogen fluxes were measured at altitudes of 120-200 km by a rocket payload that also measured electron and proton fluxes and vector magnetic fields. An intense electron arc was crossed, while an upper limit to the flux of 0.5- to 20-keV protons was 1,000,000 per sq cm s sr keV. A neutral flux of 50,000,000 per sq cm s sr was observed, assuming hydrogen with greater than 1-keV energy, with greater north-south extent than the electron flux. Its pitch angle distribution was peaked toward 90 deg, tending toward isotropy in the center. This is fitted to a model describing spreading of an initial proton arc above 500 km.

  17. Simulation of high-energy radiation belt electron fluxes using NARMAX-VERB coupled codes.

    PubMed

    Pakhotin, I P; Drozdov, A Y; Shprits, Y Y; Boynton, R J; Subbotin, D A; Balikhin, M A

    2014-10-01

    This study presents a fusion of data-driven and physics-driven methodologies of energetic electron flux forecasting in the outer radiation belt. Data-driven NARMAX (Nonlinear AutoRegressive Moving Averages with eXogenous inputs) model predictions for geosynchronous orbit fluxes have been used as an outer boundary condition to drive the physics-based Versatile Electron Radiation Belt (VERB) code, to simulate energetic electron fluxes in the outer radiation belt environment. The coupled system has been tested for three extended time periods totalling several weeks of observations. The time periods involved periods of quiet, moderate, and strong geomagnetic activity and captured a range of dynamics typical of the radiation belts. The model has successfully simulated energetic electron fluxes for various magnetospheric conditions. Physical mechanisms that may be responsible for the discrepancies between the model results and observations are discussed.

  18. Simulation of high-energy radiation belt electron fluxes using NARMAX-VERB coupled codes

    PubMed Central

    Pakhotin, I P; Drozdov, A Y; Shprits, Y Y; Boynton, R J; Subbotin, D A; Balikhin, M A

    2014-01-01

    This study presents a fusion of data-driven and physics-driven methodologies of energetic electron flux forecasting in the outer radiation belt. Data-driven NARMAX (Nonlinear AutoRegressive Moving Averages with eXogenous inputs) model predictions for geosynchronous orbit fluxes have been used as an outer boundary condition to drive the physics-based Versatile Electron Radiation Belt (VERB) code, to simulate energetic electron fluxes in the outer radiation belt environment. The coupled system has been tested for three extended time periods totalling several weeks of observations. The time periods involved periods of quiet, moderate, and strong geomagnetic activity and captured a range of dynamics typical of the radiation belts. The model has successfully simulated energetic electron fluxes for various magnetospheric conditions. Physical mechanisms that may be responsible for the discrepancies between the model results and observations are discussed. PMID:26167432

  19. Energetic electron precipitation into the middle atmosphere -- Constructing the loss cone fluxes from MEPED POES

    NASA Astrophysics Data System (ADS)

    Nesse Tyssøy, H.; Sandanger, M. I.; Ødegaard, L.-K. G.; Stadsnes, J.; Aasnes, A.; Zawedde, A. E.

    2016-06-01

    The impact of energetic electron precipitation (EEP) on the chemistry of the middle atmosphere (50-90 km) is still an outstanding question as accurate quantification of EEP is lacking due to instrumental challenges and insufficient pitch angle coverage of current particle detectors. The Medium Energy Proton and Electron Detectors (MEPED) instrument on board the NOAA/Polar Orbiting Environmental Satellites (POES) and MetOp spacecraft has two sets of electron and proton telescopes pointing close to zenith (0°) and in the horizontal plane (90°). Using measurements from either the 0° or 90° telescope will underestimate or overestimate the bounce loss cone flux, respectively, as the energetic electron fluxes are often strongly anisotropic with decreasing fluxes toward the center of the loss cone. By combining the measurements from both telescopes with electron pitch angle distributions from theory of wave-particle interactions in the magnetosphere, a complete bounce loss cone flux is constructed for each of the electron energy channels >50 keV, >100 keV, and >300 keV. We apply a correction method to remove proton contamination in the electron counts. We also account for the relativistic (>1000 keV) electrons contaminating the proton detector at subauroral latitudes. This gives us full range coverage of electron energies that will be deposited in the middle atmosphere. Finally, we demonstrate the method's applicability on strongly anisotropic pitch angle distributions during a weak geomagnetic storm in February 2008. We compare the electron fluxes and subsequent energy deposition estimates to OH observations from the Microwave Limb Sounder on the Aura satellite substantiating that the estimated fluxes are representative for the true precipitating fluxes impacting the atmosphere.

  20. Electronic Reliability and the Environmental Thermal Neutron Flux

    DTIC Science & Technology

    2007-11-02

    several Californium sources of varying strengths. The room is ten by ten by three meters. It is below ground with concrete walls. In a high flux...desirable for calibrating the system. Californium -252 is a self-fissioning fast neutron source, which can be moderated to produce thermal neutrons...NIST has several Californium sources with strengths as high as 200 mrem/h at one meter. The Cf sources are stored below the floor for the safety

  1. Electron heat flux dropouts in the solar wind - Evidence for interplanetary magnetic field reconnection?

    NASA Technical Reports Server (NTRS)

    Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.; Bame, S. J.; Luhmann, J. G.; Smith, E. J.

    1989-01-01

    An examination of ISEE-3 data from 1978 reveal 25 electron heat flux dropout events ranging in duration from 20 min to over 11 hours. The heat flux dropouts are found to occur in association with high plasma densities, low plasma velocities, low ion and electron temperatures, and low magnetic field magnitudes. It is suggested that the heat flux dropout intervals may indicate that the spacecraft is sampling plasma regimes which are magnetically disconnected from the sun and instead are connected to the outer heliosphere at both ends.

  2. The association of spacecraft anomalies with electron/proton particle fluxes at different orbits

    NASA Astrophysics Data System (ADS)

    Yi, K.; Moon, Y. J.

    2016-12-01

    In this study, we investigate 195 satellite anomaly data from 1998 to 2010 from Satellite News Digest (SND) to understand the association between spacecraft anomaly and space weather condition. The spacecraft anomalies are classified into Attitude & Propulsion, Power, Control, Telemetry, Instrument and unknown. For the investigation we divide these data according to the spacecraft orbit and launched year. Spacecraft's orbits are classified into the following two groups : (1) high altitude and low inclination, and (2) low altitude and high inclination. Launched year of spacecraft are divided into two groups: 1991 1998 and 1999 2007. We examine the association between these anomaly data and daily peak particle (electron and proton) flux data from GOES as well as their occurrence rates. To determine the association, we use two criteria that electron criterion is >10,000 pfu and proton criterion is >100 pfu. Main results from this study are as follows. First, the number of days satisfying the criteria for electron flux has a peak near a week before the anomaly day and decreases from the peak day to the anomaly day, while that for proton flux has a peak near the anomaly day. Second, we found a similar pattern for the mean daily peak particle (electron and proton) flux as a function of day before the anomaly day. Third, an examination of multiple spacecraft anomaly events, which are likely to occur by severe space weather effects, shows that anomalies mostly occur either when electron fluxes are in the declining stage, or when daily proton peak fluxes are strongly enhanced. Fourth, the time delay between the anomaly day and the day having the highest daily peak electron flux for the recent launching period (1999-2007) is noticeably larger than those for the older periods, implying that the anomaly characteristics associated with electron flux change with time.

  3. Simultaneous plasma wave and electron flux observations upstream of the Martian bow shock

    NASA Astrophysics Data System (ADS)

    Skalsky, A.; Grard, R.; Kiraly, P.; Klimov, S.; Kopanyi, V.; Schwingenschuh, K.; Trotignon, J. G.

    1993-03-01

    Flux enhancements of electrons with energies between 100 and 530 eV are observed simultaneously with electron plasma waves in the upstream region of the Martian bow shock. The electron flux appears to reach its maximum when the pitch angle is close to 0 deg, which corresponds to particles reflected from the shock region and backstreaming in the solar wind along the magnetic field. The correlation between high-frequency waves and enhanced electron fluxes is reminiscent of several studies on the electron foreshock of the Earth. Such a similarity indicates that, in spite of major differences between the global shock structures, the microscopic processes operating in the foreshocks of Earth and Mars are probably identical.

  4. Evaluation of the Antiproton Flux from the Antineutrino Electron Scattering

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Belotsky, K. M.; Bogomolov, Yu V.; Budaev, R. I.; Dunaeva, O. A.; Kirillov, A. A.; Kuznetsov, A. V.; Laletin, M. N.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Mayorova, M. A.; Mosichkin, A. F.; Okrugin, A. A.; Rodenko, S. A.; Shitova, A. M.

    2016-02-01

    Recent experiments in high enegry cosmic ray physics, PAMELA and AMS-02, excite a new interest to the mechanisms of generation of galactic antiparticles. In spite of the fact that global picture coincides with the predictions of the standard model, there are some black spots stimulating scientists to involve into research a particularly new physics like dark matter. In the present work, we make an attempt to estimate the impact of standard neutrino processes into the total flux of secondary antiprotons detected by contemporary experiments.

  5. A statistical approach to determining energetic outer radiation belt electron precipitation fluxes

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, Mea; Clilverd, Mark A.; Rodger, Craig J.; Cresswell-Moorcock, Kathy; Cobbett, Neil; Breen, Paul; Danskin, Donald; Spanswick, Emma; Rodriguez, Juan V.

    2014-05-01

    Subionospheric radio wave data from an Antarctic-Arctic Radiation-Belt (Dynamic) Deposition VLF Atmospheric Research Konsortia (AARDDVARK) receiver located in Churchill, Canada, is analyzed to determine the characteristics of electron precipitation into the atmosphere over the range 3 < L < 7. The study advances previous work by combining signals from two U.S. transmitters from 20 July to 20 August 2010, allowing error estimates of derived electron precipitation fluxes to be calculated, including the application of time-varying electron energy spectral gradients. Electron precipitation observations from the NOAA POES satellites and a ground-based riometer provide intercomparison and context for the AARDDVARK measurements. AARDDVARK radiowave propagation data showed responses suggesting energetic electron precipitation from the outer radiation belt starting 27 July 2010 and lasting ~20 days. The uncertainty in >30 keV precipitation flux determined by the AARDDVARK technique was found to be ±10%. Peak >30 keV precipitation fluxes of AARDDVARK-derived precipitation flux during the main and recovery phase of the largest geomagnetic storm, which started on 4 August 2010, were >105 el cm-2 s-1 sr-1. The largest fluxes observed by AARDDVARK occurred on the dayside and were delayed by several days from the start of the geomagnetic disturbance. During the main phase of the disturbances, nightside fluxes were dominant. Significant differences in flux estimates between POES, AARDDVARK, and the riometer were found after the main phase of the largest disturbance, with evidence provided to suggest that >700 keV electron precipitation was occurring. Currently the presence of such relativistic electron precipitation introduces some uncertainty in the analysis of AARDDVARK data, given the assumption of a power law electron precipitation spectrum.

  6. Quasi-exospheric heat flux of solar-wind electrons

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Schultz, M.

    1975-01-01

    Density, bulk-velocity, and heat-flow moments are calculated for truncated Maxwellian distributions representing the cool and hot populations of solar-wind electrons, as realized at the base of a hypothetical exosphere. The electrostatic potential is thus calculated by requiring charge quasi-neutrality and the absence of electrical current. Plasma-kinetic coupling of the cool-electron and proton bulk velocities leads to an increase in the electrostatic potential and a decrease in the heat-flow moment.

  7. Rocket measurements of relativistic electrons: New features in fluxes, spectra and pitch angle distributions

    SciTech Connect

    Herrero, F.A.; Baker, D.N.; Goldberg, R.A. )

    1991-08-01

    The authors report new features of precipitating relativistic electron fluxes measured on a spinning sounding rocket payload at midday between altitudes of 70 and 130 km in the auroral region (Poker Flat, Alaska, 65.1{degree}N, 147.5{degree}W, and L = 5.5). The sounding rocket (NASA 33.059) was launched at 21:29 UT on May 13, 1990 during a relativistic electron enhancement event of modest intensity. Electron fluxes were measured for a total of about 210 seconds at energies from 0.1 to 3.8 MeV, while pitch angle was sampled from 0{degree} to 90{degree} every spin cycle. Flux levels during the initial 90 seconds were about 5 to 8 times higher than in the next 120 seconds, revealing a time scale of more than 100 seconds for large amplitude intensity variations. A shorter time scale appeared for downward electron bursts lasting 10 to 20 seconds. Electrons with energies below about 0.2 MeV showed isotropic pitch angle distributions during most of the first 90 seconds of data, while at higher energies the electrons had highest fluxes near the mirroring angle (90{degree}); when they occurred, the noted downward bursts were seen at all energies. Data obtained during the second half of the flight showed little variation in the shape of the pitch angle distribution for energies greater than 0.5 MeV; the flux at 90{degree} was about 100 times the flux at 0{degree}. They have compared the low altitude fluxes with those measured at geostationary orbit (L = 6.6), and find that the low altitude fluxes are much higher than expected from a simple mapping of a pancake distribution at high altitudes (at the equator). Energy deposition of this modest event is estimated to increase rapidly above 45 km, already exceeding the cosmic ray background at 45 km.

  8. The seasonal dependence of relativistic electron fluxes in the Earth's outer van Allen Belt

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; McPherron, R.

    2007-12-01

    It is well known that geomagnetic activity shows a marked seasonal dependence. This effect has been attributed to the seasonal variation of the Earth's dipole tilt angle exposing the magnetosphere to an increased southward component of the interplanetary field (the Russell-McPherron effect) or an increased solar wind velocity (the axial/equinoctial effect). We examine the seasonal dependence of relativistic electron fluxes in the Earth's outer Van Allen belt. An earlier investigation by Baker et. al., (1999) found that the relativistic electron fluxes do show a strong seasonal dependence with the equinoctial electron fluxes being almost three times higher than the solstitial fluxes. We extend this previous investigation using data obtained by sensors onboard SAMPEX. This study of the seasonal dependence is based on data with a higher time resolution as compared to the earlier study. The results of our analysis show that the peak electron fluxes are shifted in time from the nominal equinoctial times. We discuss some possible implications of our observations in the context of electron energization in the Earth's magnetosphere. Baker, D.N., S.G. Kanekal, T.I. Pulkkinen, and J.B. Blake, Equinoctial and solstitial averages of magnetospheric relativistic electrons: A strong semiannual modulation, Geophys. Res. Lett., 26, No. 20, 3193-3196, 1999.

  9. Predictions of vehicle encountered electron and proton fluxes for the UK-4 spacecraft

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.

    1972-01-01

    Updated radiation data were obtained for the UK-4 satellite by performing orbital flux integrations for protons and electrons along a specified flight path, using current field and environment models. In this process, adjustments were made to the electron data to account for temporal variations. The final results are presented in tabular and graphical form.

  10. Rapid increase in relativistic electron flux controlled by nonlinear phase trapping of whistler chorus elements

    NASA Astrophysics Data System (ADS)

    Saito, Shinji; Miyoshi, Yoshizumi; Seki, Kanako

    2016-07-01

    Wave-particle interactions with whistler chorus waves are believed to provide a primary acceleration for electrons in the outer radiation belt. Previous models for flux enhancement of the radiation belt have assumed the stochastic process as a diffusion manner of successive random-phase interactions, but physical mechanisms for the acceleration are not fully incorporated in these models because of the lack of a nonlinear scattering process. Here we report rapid increase in relativistic electron flux by using an innovative computer simulation model that incorporates not only diffusive process but also nonlinear scattering processes. The simulations show that three types of scattering simultaneously occur, which are diffusive, phase trapping, and phase bunching. It is found that the phase trapping is the most efficient mechanism to produce the MeV electrons rapidly in the scattering processes. The electrons are accelerated from 400 keV to over 1 MeV in time scale less than 60 s. On the other hand, as the phase trapping is suppressed by the breaking of relative phase angle between waves and gyrating electrons during the interaction, the increase of electron flux at MeV energy is clearly reduced. Our simulations conclude that the phase-trapping process causes a significant effect for the increase in relativistic electron flux and suggest that a quasi-linear diffusion model is not always valid to fully describe the relativistic electron acceleration.

  11. High flux, narrow bandwidth compton light sources via extended laser-electron interactions

    DOEpatents

    Barty, V P

    2015-01-13

    New configurations of lasers and electron beams efficiently and robustly produce high flux beams of bright, tunable, polarized quasi-monoenergetic x-rays and gamma-rays via laser-Compton scattering. Specifically, the use of long-duration, pulsed lasers and closely-spaced, low-charge and low emittance bunches of electron beams increase the spectral flux of the Compton-scattered x-rays and gamma rays, increase efficiency of the laser-electron interaction and significantly reduce the overall complexity of Compton based light sources.

  12. Diagnosing pure-electron plasmas with internal particle flux probes.

    PubMed

    Kremer, J P; Pedersen, T Sunn; Marksteiner, Q; Lefrancois, R G; Hahn, M

    2007-01-01

    Techniques for measuring local plasma potential, density, and temperature of pure-electron plasmas using emissive and Langmuir probes are described. The plasma potential is measured as the least negative potential at which a hot tungsten filament emits electrons. Temperature is measured, as is commonly done in quasineutral plasmas, through the interpretation of a Langmuir probe current-voltage characteristic. Due to the lack of ion-saturation current, the density must also be measured through the interpretation of this characteristic thereby greatly complicating the measurement. Measurements are further complicated by low densities, low cross field transport rates, and large flows typical of pure-electron plasmas. This article describes the use of these techniques on pure-electron plasmas in the Columbia Non-neutral Torus (CNT) stellarator. Measured values for present baseline experimental parameters in CNT are phi(p)=-200+/-2 V, T(e)=4+/-1 eV, and n(e) on the order of 10(12) m(-3) in the interior.

  13. APS high heat load monochromator

    SciTech Connect

    Lee, W.K.; Mills, D.

    1993-02-01

    This document contains the design specifications of the APS high heat load (HHL) monochromator and associated accessories as of February 1993. It should be noted that work is continuing on many parts of the monochromator including the mechanical design, crystal cooling designs, etc. Where appropriate, we have tried to add supporting documentation, references to published papers, and calculations from which we based our decisions. The underlying philosophy behind performance specifications of this monochromator was to fabricate a device that would be useful to as many APS users as possible, that is, the design should be as generic as possible. In other words, we believe that this design will be capable of operating on both bending magnet and ID beamlines (with the appropriate changes to the cooling and crystals) with both flat and inclined crystal geometries and with a variety of coolants. It was strongly felt that this monochromator should have good energy scanning capabilities over the classical energy range of about 4 to 20 keywith Si (111) crystals. For this reason, a design incorporating one rotation stage to drive both the first and second crystals was considered most promising. Separate rotary stages for the first and second crystals can sometimes provide more flexibility in their capacities to carry heavy loads (for heavily cooled first crystals or sagittal benders of second crystals), but their tuning capabilities were considered inferior to the single axis approach.

  14. APS high heat load monochromator

    SciTech Connect

    Lee, W.K.; Mills, D.

    1993-02-01

    This document contains the design specifications of the APS high heat load (HHL) monochromator and associated accessories as of February 1993. It should be noted that work is continuing on many parts of the monochromator including the mechanical design, crystal cooling designs, etc. Where appropriate, we have tried to add supporting documentation, references to published papers, and calculations from which we based our decisions. The underlying philosophy behind performance specifications of this monochromator was to fabricate a device that would be useful to as many APS users as possible, that is, the design should be as generic as possible. In other words, we believe that this design will be capable of operating on both bending magnet and ID beamlines (with the appropriate changes to the cooling and crystals) with both flat and inclined crystal geometries and with a variety of coolants. It was strongly felt that this monochromator should have good energy scanning capabilities over the classical energy range of about 4 to 20 keywith Si (111) crystals. For this reason, a design incorporating one rotation stage to drive both the first and second crystals was considered most promising. Separate rotary stages for the first and second crystals can sometimes provide more flexibility in their capacities to carry heavy loads (for heavily cooled first crystals or sagittal benders of second crystals), but their tuning capabilities were considered inferior to the single axis approach.

  15. Analysis of Voyager Observed High-Energy Electron Fluxes in the Heliosheath Using MHD Simulations

    NASA Technical Reports Server (NTRS)

    Washimi, Haruichi; Webber, W. R.; Zank, Gary P.; Hu, Qiang; Florinski, Vladimir; Adams, James; Kubo, Yuki

    2011-01-01

    The Voyager spacecraft (V1 and V2) observed electrons of 6-14 MeV in the heliosheath which showed several incidences of flux variation relative to a background of gradually increasing flux with distance from the Sun. The increasing flux of background electrons is thought to result from inward radial diffusion. We compare the temporal electron flux variation with dynamical phenomena in the heliosheath that are obtained from our MHD simulations. Because our simulation is based on V2 observed plasma data before V2 crossed the termination shock, this analysis is effective up to late 2008, i.e., about a year after the V2-crossing, during which disturbances, driven prior to the crossing time, survived in the heliosheath. Several electron flux variations correspond to times directly associated with interplanetary shock events. One noteworthy example corresponds to various times associated with the March 2006 interplanetary shock, these being the collision with the termination shock, the passage past the V1 spacecraft, and the collision with the region near the heliopause, as identified by W.R. Webber et al. for proton/helium of 7-200 MeV. Our simulations indicate that all other electron flux variations, except one, correspond well to the times when a shock-driven magneto-sonic pulse and its reflection in the heliosheath either passed across V1/V2, or collided with the termination shock or with the plasma sheet near the heliopause. This result suggests that variation in the electron flux should be due to either direct or indirect effects of magnetosonic pulses in the heliosheath driven by interplanetary shocks

  16. The Electronic Flux in Chemical Reactions. Insights on the Mechanism of the Maillard Reaction

    NASA Astrophysics Data System (ADS)

    Flores, Patricio; Gutiérrez-Oliva, Soledad; Herrera, Bárbara; Silva, Eduardo; Toro-Labbé, Alejandro

    2007-11-01

    The electronic transfer that occurs during a chemical process is analysed in term of a new concept, the electronic flux, that allows characterizing the regions along the reaction coordinate where electron transfer is actually taking place. The electron flux is quantified through the variation of the electronic chemical potential with respect to the reaction coordinate and is used, together with the reaction force, to shed light on reaction mechanism of the Schiff base formation in the Maillard reaction. By partitioning the reaction coordinate in regions in which different process might be taking place, electronic reordering associated to polarization and transfer has been identified and found to be localized at specific transition state regions where most bond forming and breaking occur.

  17. Correlation between Poynting flux and soft electron precipitation in the dayside polar cap boundary regions.

    PubMed

    Deng, Yue; Sheng, Cheng; Su, Yi-Jiun; Hairston, Marc R; Knipp, Delores; Huang, Cheryl Y; Ober, Daniel; Redmon, Rob J; Coley, Robin

    2015-10-01

    Observations have revealed large Poynting flux and soft electron precipitation around the cusp region, which have strong impacts on the polar ionosphere/thermosphere. Simulations also confirmed that Poynting flux and soft electron precipitation significantly change the neutral density and dynamics around the dayside polar cap boundary regions. However, no detailed study has been conducted to show if they should coincide with each other or not. Our analysis of Defense Meteorological Satellite Program (DMSP) satellite data reveals a complex correlation between them. Poynting flux and soft particle precipitation are coincident in some cases (match cases), but a clear displacement between them can also be identified in others (nonmatch cases). In the 29 cusp crossings from F13 we investigated, the ratio between nonmatch and match cases is close to 1:4. In nonmatch cases, the displacement between the Poynting flux enhancement and soft particle precipitation enhancement can be as large as 1° in geomagnetic latitude.

  18. Vortices and Flux Ropes in Electron MHD Plasmas I

    NASA Astrophysics Data System (ADS)

    Stenzel, R. L.; Urrutia, J. M.; Griskey, M. C.

    Laboratory experiments are reviewed which demonstrate the existence and properties of three-dimensional vortices in Electron MHD (EMHD) plasmas. In this parameter regime the electrons form a magnetized fluid which is charge-neutralized by unmagnetized ions. The observed vortices are time-varying flows in the electron fluid which produce currents and magnetic fields, the latter superimposed on a uniform dc magnetic field B0. The topology of the time-varying flows and fields can be described by linked toroidal and poloidal vector fields with amplitude distributions ranging from spherical to cylindrical shape. Vortices can be excited with pulsed currents to electrodes, pulsed currents in magnetic loop antennas, and heat pulses. The vortices propagate in the whistler mode along the mean field B0. In the presence of dissipation, magnetic self-helicity and energy decay at the same rate. Reversal of B or propagation direction changes the sign of the helicity. Helicity injection produces directional emission of vortices. Reflection of a vortex violates helicity conservation and field-line tying. Part I of two companion papers reviews the linear vortex properties while the companion Part II describes nonlinear EMHD phenomena and instabilities.

  19. Gas dynamic theory of flight of fast electron flux in plasma

    NASA Astrophysics Data System (ADS)

    Melnik, V. N.

    The one-dimensional flight of a fast electron flux in plasma is investigated taking into account generation and absorption of plasma waves. The transition from the kinetic description to the gas dynamics is made. The closed set of gas dynamic equations for electrons and plasmons is derived and an automodel solution is obtained in the case of instantaneous injection. This solution represents the beam-plasma formation on natural oscillations in the system electrons+plasmons is considered.

  20. Magnetic-flux quanta in superconducting thin films observed by electron holography and digital phase analysis

    SciTech Connect

    Hasegawa, S.; Matsuda, T.; Endo, J.; Osakabe, N.; Igarashi, M.; Kobayashi, T.; Naito, M.; Tonomura, A. ); Aoki, R. )

    1991-04-01

    Singly quantized magnetic fluxes in superconducting lead films have been directly observed in the form of magnetic-flux-line distributions by using an electron-holography technique. Combining this with the digital-phase-analysis method, we were able to determine the flux quantum {ital h}/2{ital e} for individual fluxes with a precision of {similar to}{ital h}/100{ital e}, and analyze the distributions of field-vector components around the fluxon centers. The internal-field distributions obtained were compared with those calculated from the Ginzburg-Landau equations with use of some models, and an overall agreement was found between them. We also observed the changes of the magnetic-flux structures of lead thin films as a function of their thickness. Fluxon pairs were observed in 0.2-{mu}m-thick films, which may correspond to those suggested by Kosterlitz-Thouless theory.

  1. The sum of flux control coefficients in the electron-transport chain of mitochondria.

    PubMed

    Brand, M D; Vallis, B P; Kesseler, A

    1994-12-15

    The sum of the flux control coefficients for group-transfer reactions such as electron transport has been proposed to be two when the coefficients are calculated from experiments in which the concentrations of the electron carriers are changed (CE) but one when they are calculated from changes in the rates of the electron-transfer processes (Cv). We tested this proposal using electron transport in uncoupled beef heart, potato tuber and rat liver mitochondria. First, with ascorbate plus N,N,N',N"-tetramethyl-p-phenylenediamine as substrate, the CE flux control coefficients of ascorbate, N,N,N',N"-tetramethyl-p-phenylenediamine, mitochondria and oxygen over electron-transport rate were measured by direct titration of the concentrations of these electron carriers. CE values were close to zero, one, one and zero, respectively, giving a sum of CE flux control coefficients of approximately two. At higher concentrations of N,N,N',N'-tetramethyl-p-phenylenediamine, its CE control decreased and the sum decreased towards one as predicted. Secondly, the Cv control coefficients of groups of electron-transfer processes with succinate or ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine as substrate were measured. This was achieved by measuring the effects of KCN (or malonate or N,N,N',N'-tetramethyl-p-phenylenediamine) on system flux when intermediates were allowed to relax and on local flux when intermediates were held constant. The Cv flux control coefficients were calculated as the ratio of the effects on system flux and on local flux. The sum of the Cv flux control coefficients was approximately one. Whether a sum of one or a sum of two was obtained depended entirely on the definition of control coefficients that was used, since either sum was obtained from the same set of data depending on the method of calculation. Both definitions are valid, but they give different information. It is important to be aware of which definition is being used when analysing control

  2. Low-energy electron flux and its reaction to active experimentation of Spacelab

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.

    1981-01-01

    An instrument capable of observing the natural electron flux in the energy range from 0.1 to 12.0 kiloelectron volts is discussed for use in an experiment intended as a forerunner of a method that will utilize artificially accelerated electrons as tracer particles for electron fields parallel to the magnetic field. Effects that are of importance either as means of detecting the echo beam or as causes of beam perturbations (e.g., spacecraft charging effects and electron background) are to be studied. The use of electron accelerators as a tool to probe magnetospheric processes rather than to modify them is planned.

  3. An empirical model of electron and ion fluxes derived from observations at geosynchronous orbit

    SciTech Connect

    Denton, M. H.; Thomsen, M. F.; Jordanova, V. K.; Henderson, M. G.; Borovsky, J. E.; Denton, J. S.; Pitchford, D.; Hartley, D. P.

    2015-04-01

    Knowledge of the plasma fluxes at geosynchronous orbit is important to both scientific and operational investigations. We present a new empirical model of the ion flux and the electron flux at geosynchronous orbit (GEO) in the energy range ~1 eV to ~40 keV. The model is based on a total of 82 satellite-years of observations from the Magnetospheric Plasma Analyzer instruments on Los Alamos National Laboratory satellites at GEO. These data are assigned to a fixed grid of 24 local-times and 40 energies, at all possible values of Kp. Bi-linear interpolation is used between grid points to provide the ion flux and the electron flux values at any energy and local-time, and for given values of geomagnetic activity (proxied by the 3-hour Kp index), and also for given values of solar activity (proxied by the daily F10.7 index). Initial comparison of the electron flux from the model with data from a Compact Environmental Anomaly Sensor II (CEASE-II), also located at geosynchronous orbit, indicate a good match during both quiet and disturbed periods. The model is available for distribution as a FORTRAN code that can be modified to suit user-requirements.

  4. An empirical model of electron and ion fluxes derived from observations at geosynchronous orbit

    DOE PAGES

    Denton, M. H.; Thomsen, M. F.; Jordanova, V. K.; ...

    2015-04-01

    Knowledge of the plasma fluxes at geosynchronous orbit is important to both scientific and operational investigations. We present a new empirical model of the ion flux and the electron flux at geosynchronous orbit (GEO) in the energy range ~1 eV to ~40 keV. The model is based on a total of 82 satellite-years of observations from the Magnetospheric Plasma Analyzer instruments on Los Alamos National Laboratory satellites at GEO. These data are assigned to a fixed grid of 24 local-times and 40 energies, at all possible values of Kp. Bi-linear interpolation is used between grid points to provide the ionmore » flux and the electron flux values at any energy and local-time, and for given values of geomagnetic activity (proxied by the 3-hour Kp index), and also for given values of solar activity (proxied by the daily F10.7 index). Initial comparison of the electron flux from the model with data from a Compact Environmental Anomaly Sensor II (CEASE-II), also located at geosynchronous orbit, indicate a good match during both quiet and disturbed periods. The model is available for distribution as a FORTRAN code that can be modified to suit user-requirements.« less

  5. Properties of electron flux spectra around the plasmapause in the chorus and hiss regions using POES.

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian; Rodger, Craig; Clilverd, Mark

    2014-05-01

    The European FP7 PLASMON project aims to provide observations of plasmaspheric densities, and link the plasmaspheric variations to relativistic electron precipitation from the radiation belts. This is intended to assist in the estimation and prevent damage of space assets from space weather events as well as to improve forecasting (http://plasmon.elte.hu). As part of the PLASMON project, electron fluxes from the POES series of satellites are being used to determine the link between energetic electron precipitation energy spectra and magnitude to the position of the plasmapause. The MEPED instrument onboard POES measures electron flux from 90° (trapped particles) and 0° (losscone) telescopes, in 3 integral energy channels (>30, >100 and >300 keV). These fluxes have been compared to the DEMETER/IDP instrument to confirm that published geometric factor corrections (Yando et al. 2011) can be accurately applied to the POES data to produce as accurate as possible fluxes. These global fluxes have then been separated into regions in which Chorus (23:00-11:00 MLT) and Hiss (11:00-16:00 MLT) whistler mode waves are expected to occur, in 0.2 L-shell bins with a 20 minute temporal resolution. The plasmapause locations have been determined from the O'Brien and Moldwin (2003) models based on Kp, Ae and Dst peaks. We are currently comparing the POES spectral gradient and flux magnitude with plasmapause location and geomagnetic activity for the locations in which chorus and hiss are known to occur. This presentation will focus on the electron flux spectral gradient behaviour either side of the plasmapause, a value that is difficult to measure from ground based techniques.

  6. Correcting the NOAA/MEPED energetic electron fluxes for detector efficiency and proton contamination

    NASA Astrophysics Data System (ADS)

    Asikainen, T.; Mursula, K.

    2013-10-01

    The Medium Energy Proton and Electron Detector (MEPED) instruments onboard the NOAA/POES satellites have provided a valuable long-term database of low-altitude energetic particle observations spanning from 1978 to present. Here we study the instrumental problems of the NOAA/MEPED electron detectors and present methods to correct them. It is well known that the MEPED electron detectors are contaminated by protons of certain energy range. Using the recently corrected MEPED proton fluxes, we are now able to reliably remove this contamination. Using a simple simulation model to estimate the response of the MEPED electron detectors to incoming electrons and protons, we show that efficiencies of (Space Environment Monitors) SEM-1 and SEM-2 versions of the detectors have large differences due to different detector designs. This leads to a systematic difference between the SEM-1 and SEM-2 measurements and causes a significant long-term inhomogeneity in measured MEPED electron fluxes. Using the estimated efficiencies, we remove the proton contamination and correct the electron measurements for nonideal detector efficiency. We discuss the entire 34 year time series of MEPED measurements and show that, on an average, the correction affects different energy channels and SEM-1 and SEM-2 instruments differently. Accordingly, the uncorrected electron fluxes and electron spectra are severely distorted by nonideal detector efficiency and proton contamination, and their long-term evolution is misrepresented without the correction. The present correction of the MEPED electron fluxes over the whole interval of NOAA/POES measurements covering several solar cycles is important for long-term studies of, e.g., magnetospheric dynamics, solar activity, ionospheric research, and atmospheric effects of energetic electrons.

  7. Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

    NASA Astrophysics Data System (ADS)

    Aguilar, M.; Aisa, D.; Alvino, A.; Ambrosi, G.; Andeen, K.; Arruda, L.; Attig, N.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Battarbee, M.; Battiston, R.; Bazo, J.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bigongiari, G.; Bindi, V.; Bizzaglia, S.; Bizzarri, M.; Boella, G.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Borsini, S.; Boschini, M. J.; Bourquin, M.; Burger, J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Cascioli, V.; Castellini, G.; Cernuda, I.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, H.; Cheng, G. M.; Chen, H. S.; Cheng, L.; Chikanian, A.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Coste, B.; Cui, Z.; Dai, M.; Delgado, C.; Della Torre, S.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Di Masso, L.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Du, W. J.; Duranti, M.; D'Urso, D.; Eline, A.; Eppling, F. J.; Eronen, T.; Fan, Y. Y.; Farnesini, L.; Feng, J.; Fiandrini, E.; Fiasson, A.; Finch, E.; Fisher, P.; Galaktionov, Y.; Gallucci, G.; García, B.; García-López, R.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Gillard, W.; Giovacchini, F.; Goglov, P.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guandalini, C.; Guerri, I.; Guo, K. H.; Habiby, M.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jinchi, H.; Kanishev, K.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Kossakowski, R.; Kounina, O.; Kounine, A.; Koutsenko, V.; Krafczyk, M. S.; Kunz, S.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. L.; Li, J. Q.; Li, Q.; Li, Q.; Li, T. X.; Li, W.; Li, Y.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, H.; Lomtadze, T.; Lu, M. J.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lv, S. S.; Majka, R.; Malinin, A.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mo, D. C.; Morescalchi, L.; Mott, P.; Müller, M.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Nunes, P.; Obermeier, A.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Papi, A.; Pedreschi, E.; Pensotti, S.; Pereira, R.; Pilo, F.; Piluso, A.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Postaci, E.; Putze, A.; Quadrani, L.; Qi, X. M.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rodríguez, I.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Sandweiss, J.; Saouter, P.; Sbarra, C.; Schael, S.; Schmidt, S. M.; Schuckardt, D.; von Dratzig, A. Schulz; Schwering, G.; Scolieri, G.; Seo, E. S.; Shan, B. S.; Shan, Y. H.; Shi, J. Y.; Shi, X. Y.; Shi, Y. M.; Siedenburg, T.; Son, D.; Spada, F.; Spinella, F.; Sun, W.; Sun, W. H.; Tacconi, M.; Tang, C. P.; Tang, X. W.; Tang, Z. C.; Tao, L.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Vannini, C.; Valtonen, E.; Vaurynovich, S.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Wang, L. Q.; Wang, Q. L.; Wang, R. S.; Wang, X.; Wang, Z. X.; Weng, Z. L.; Whitman, K.; Wienkenhöver, J.; Wu, H.; Xia, X.; Xie, M.; Xie, S.; Xiong, R. Q.; Xin, G. M.; Xu, N. S.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Ye, Q. H.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zeissler, S.; Zhang, J. H.; Zhang, M. T.; Zhang, X. B.; Zhang, Z.; Zheng, Z. M.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; Zurbach, C.; AMS Collaboration

    2014-09-01

    Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ˜30 GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

  8. Electron and positron fluxes in primary cosmic rays measured with the alpha magnetic spectrometer on the international space station.

    PubMed

    Aguilar, M; Aisa, D; Alvino, A; Ambrosi, G; Andeen, K; Arruda, L; Attig, N; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Battarbee, M; Battiston, R; Bazo, J; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bigongiari, G; Bindi, V; Bizzaglia, S; Bizzarri, M; Boella, G; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Borsini, S; Boschini, M J; Bourquin, M; Burger, J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Cascioli, V; Castellini, G; Cernuda, I; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, H; Cheng, G M; Chen, H S; Cheng, L; Chikanian, A; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Coste, B; Cui, Z; Dai, M; Delgado, C; Della Torre, S; Demirköz, M B; Derome, L; Di Falco, S; Di Masso, L; Dimiccoli, F; Díaz, C; von Doetinchem, P; Du, W J; Duranti, M; D'Urso, D; Eline, A; Eppling, F J; Eronen, T; Fan, Y Y; Farnesini, L; Feng, J; Fiandrini, E; Fiasson, A; Finch, E; Fisher, P; Galaktionov, Y; Gallucci, G; García, B; García-López, R; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Gillard, W; Giovacchini, F; Goglov, P; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guandalini, C; Guerri, I; Guo, K H; Habiby, M; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jinchi, H; Kanishev, K; Kim, G N; Kim, K S; Kirn, Th; Kossakowski, R; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M S; Kunz, S; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H L; Li, J Q; Li, Q; Li, Q; Li, T X; Li, W; Li, Y; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, H; Lomtadze, T; Lu, M J; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lv, S S; Majka, R; Malinin, A; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mo, D C; Morescalchi, L; Mott, P; Müller, M; Ni, J Q; Nikonov, N; Nozzoli, F; Nunes, P; Obermeier, A; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Papi, A; Pedreschi, E; Pensotti, S; Pereira, R; Pilo, F; Piluso, A; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Postaci, E; Putze, A; Quadrani, L; Qi, X M; Rancoita, P G; Rapin, D; Ricol, J S; Rodríguez, I; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Sandweiss, J; Saouter, P; Sbarra, C; Schael, S; Schmidt, S M; Schuckardt, D; Schulz von Dratzig, A; Schwering, G; Scolieri, G; Seo, E S; Shan, B S; Shan, Y H; Shi, J Y; Shi, X Y; Shi, Y M; Siedenburg, T; Son, D; Spada, F; Spinella, F; Sun, W; Sun, W H; Tacconi, M; Tang, C P; Tang, X W; Tang, Z C; Tao, L; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Vaurynovich, S; Vecchi, M; Velasco, M; Vialle, J P; Wang, L Q; Wang, Q L; Wang, R S; Wang, X; Wang, Z X; Weng, Z L; Whitman, K; Wienkenhöver, J; Wu, H; Xia, X; Xie, M; Xie, S; Xiong, R Q; Xin, G M; Xu, N S; Xu, W; Yan, Q; Yang, J; Yang, M; Ye, Q H; Yi, H; Yu, Y J; Yu, Z Q; Zeissler, S; Zhang, J H; Zhang, M T; Zhang, X B; Zhang, Z; Zheng, Z M; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P; Zurbach, C

    2014-09-19

    Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ∼30  GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

  9. Geodesic mode instability driven by electron and ion fluxes in tokamaks

    SciTech Connect

    Elfimov, A. G. Camilo de Souza, F.; Galvão, R. M. O.

    2015-11-15

    The effect of the parallel electron current and plasma flux on Geodesic Acoustic Modes (GAM) in a tokamak is analyzed by kinetic theory taking into the account the ion Landau damping and diamagnetic drifts. It is shown that the electron current and plasma flow, modeled by shifted Maxwell distributions of electrons and ions, may overcome the ion Landau damping generating the GAM instability when the parallel electron current velocity is larger than the effective parallel GAM phase velocity of sidebands, Rqω. The instability is driven by the electron current and the parallel ion flux cross term. Possible applications to tokamak experiments are discussed. The existence of the geodesic ion sound mode due to plasma flow is shown.

  10. Whistler Mode Waves and the Electron Heat Flux in the Solar Wind: Cluster Observations

    NASA Astrophysics Data System (ADS)

    Lacombe, C.; Alexandrova, O.; Matteini, L.; Santolík, O.; Cornilleau-Wehrlin, N.; Mangeney, A.; de Conchy, Y.; Maksimovic, M.

    2014-11-01

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free solar wind. In ~10% of the selected data, we observe narrowband, right-handed, circularly polarized fluctuations, with wave vectors quasi-parallel to the mean magnetic field, superimposed on the spectrum of the permanent background turbulence. We interpret these coherent fluctuations as whistler mode waves. The lifetime of these waves varies between a few seconds and several hours. Here, we present, for the first time, an analysis of long-lived whistler waves, i.e., lasting more than five minutes. We find several necessary (but not sufficient) conditions for the observation of whistler waves, mainly a low level of background turbulence, a slow wind, a relatively large electron heat flux, and a low electron collision frequency. When the electron parallel beta factor β e∥ is larger than 3, the whistler waves are seen along the heat flux threshold of the whistler heat flux instability. The presence of such whistler waves confirms that the whistler heat flux instability contributes to the regulation of the solar wind heat flux, at least for β e∥ >= 3, in slow wind at 1 AU.

  11. Increases of relativistic and subrelativistic electron fluxes and position of auroral oval.

    NASA Astrophysics Data System (ADS)

    Riazantseva, Maria; Myagkova, Irina; Antonova, Elizaveta; Denisov, Yuriy I.; Marjin, Boris; Karavaev, Michael; Saveliev, Michael; Feigin, Viktor

    Increases of fluxes of relativistic and subrelativistic electrons and simultaneous plasma ob-servations are studied using data of low orbiting METEOR-3M (operating from 2001 till 2005), METEOR-M 1 (launched September 2009), CORONAS-F (2002-2005) and CORONAS-PHOTON (launched January 2009) satellites. Results of measurements are compared with simultaneous solar wind observations. The variations of particle fluxes at the external bound-ary of the outer electron radiation belt are analyzed and compared with plasma observations. The events of the appearance of local increases of energetic electron fluxes are selected. Some of these increases have near the same profile and values during 2-3 consecutive orbits. Comparison of analyzed increases and fluxes of plasma particles with energies till 10 keV show that prac-tically for all events when such comparison was possible increases of fluxes of relativistic and subrelativistic electrons were observed inside the auroral oval. The nature of observed events is discussed. It is shown that the hypothesis of the appearance of local traps for energetic particles can help to explain the observed phenomena.

  12. High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Tesileanu, Ovidiu

    2017-07-01

    Laser wakefield accelerators (LWFAs) are considered to be one of the most competitive next-generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives ˜ 40 {nC} of charge with 2 {PW} laser power, thus ˜ 400 {kA} of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.

  13. High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

    NASA Astrophysics Data System (ADS)

    Ming, ZENG; Ovidiu, TESILEANU

    2017-07-01

    Laser wakefield accelerators (LWFAs) are considered to be one of the most competitive next-generation accelerator candidates. In this paper, we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses. In our three-dimensional particle-in-cell simulations, an optimal set of parameters gives ∼ 40 {nC} of charge with 2 {PW} laser power, thus ∼ 400 {kA} of instantaneous current if we assume the electron beam duration is 100 fs. This high flux and its secondary radiation are widely applicable in nuclear and QED physics, industrial imaging, medical and biological studies.

  14. Neutrino-Electron Scattering in MINERvA for Constraining the NuMI Neutrino Flux

    SciTech Connect

    Park, Jaewon

    2013-01-01

    Neutrino-electron elastic scattering is used as a reference process to constrain the neutrino flux at the Main Injector (NuMI) beam observed by the MINERvA experiment. Prediction of the neutrino flux at accelerator experiments from other methods has a large uncertainty, and this uncertainty degrades measurements of neutrino oscillations and neutrino cross-sections. Neutrino-electron elastic scattering is a rare process, but its cross-section is precisely known. With a sample corresponding to $3.5\\times10^{20}$ protons on target in the NuMI low-energy neutrino beam, a sample of $120$ $\

  15. A new approach to predict and estimate enhancements of "killer" electron flux at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Potapov, Alexander; Ryzhakova, Larisa; Tsegmed, Battuulai

    2016-09-01

    So-called "killer" electrons are electrons of relativistic energies (more than 1-2 MeV) forming the outer radiation belt. Their fluxes present a serious threat for on-board electronics of spacecraft orbiting in geosynchronous orbit. This provides actuality of the problem of electron flux forecast. The population of energetic electrons grows after immersion of the Earth's magnetosphere into a high-speed stream of the solar wind. One of the main mechanisms of acceleration of magnetospheric electrons to relativistic energies assumed to be their wave-particle interaction with the ultra-low-frequency or very-low-frequency waves. Accordingly, the previously proposed prognostic methods were based on the connection of the outer radiation belt population with the speed of the solar wind and the activity of the low-frequency waves in the magnetosphere. In this paper, we propose to build a forecast based on a new kind of the multiple regressions model with sliding window of predictors. A set of predictors used in the successful multiple regressions model include parameters that reflect processes of replenishment of the outer radiation belt due to the acceleration of seed electrons as well as processes of the devastation of the electron flux in the geosynchronous region due to outward adiabatic transport and outward radial diffusion. To characterize these processes, we use the following set of parameters measured on the ground and in situ: the solar wind speed, density and dynamic pressure of the interplanetary plasma, the intensity of ultra-low-frequency oscillations in front of the magnetosphere and on the ground, the flux of seed electrons (of hundreds eV energy) at geosynchronous orbit, the actual values of the magnetic field at L=6.6, and interplanetary electric field. Coefficients in the model equation are derived from experimental data using the least-squares method. Test calculations using the proposed model have shown promising results.

  16. Upper limit of electron fluxes generated by kinetic Alfvén waves in Maxwellian plasma

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Rankin, R.; Vasko, I. Y.

    2016-09-01

    We consider electron acceleration by kinetic Alfvén waves in the equatorial inner magnetosphere and plasma sheet boundary layer. The competition between the accelerating effect of the wave parallel electric field and mirror force acting on particles in an inhomogeneous background magnetic field generates an effective potential well where electrons can be trapped and accelerated. We compare energy variations of trapped and transient resonant electrons and show that these variations almost compensate each other. Thus, energy provided to waves by transient particles is transferred to trapped particles. This effect allows waves accelerate trapped electrons without being significantly damped. Using energy balance equations, we estimate the maximum flux of electrons accelerated via trapping into Landau resonance with kinetic Alfvén waves. For a wide range of system parameters (i.e., ion to electron temperature ratio, magnetic field amplitude, and wave number and wave frequency), acceleration of trapped electrons can generate fluxes with amplitude about 5-25% of the background thermal fluxes. We determine parametric regions for the most efficient acceleration.

  17. Extensive electron transport and energization via multiple, localized dipolarizing flux bundles

    NASA Astrophysics Data System (ADS)

    Gabrielse, Christine; Angelopoulos, Vassilis; Harris, Camilla; Artemyev, Anton; Kepko, Larry; Runov, Andrei

    2017-05-01

    Using an analytical model of multiple dipolarizing flux bundles (DFBs) embedded in earthward traveling bursty bulk flows, we demonstrate how equatorially mirroring electrons can travel long distances and gain hundreds of keV from betatron acceleration. The model parameters are constrained by four Time History of Events and Macroscale Interactions during Substorms satellite observations, putting limits on the DFBs' speed, location, and magnetic and electric field magnitudes. We find that the sharp, localized peaks in magnetic field have such strong spatial gradients that energetic electrons ∇B drift in closed paths around the peaks as those peaks travel earthward. This is understood in terms of the third adiabatic invariant, which remains constant when the field changes on timescales longer than the electron's drift timescale: An energetic electron encircles a sharp peak in magnetic field in a closed path subtending an area of approximately constant flux. As the flux bundle magnetic field increases the electron's drift path area shrinks and the electron is prevented from escaping to the ambient plasma sheet, while it continues to gain energy via betatron acceleration. When the flux bundles arrive at and merge with the inner magnetosphere, where the background field is strong, the electrons suddenly gain access to previously closed drift paths around the Earth. DFBs are therefore instrumental in transporting and energizing energetic electrons over long distances along the magnetotail, bringing them to the inner magnetosphere and energizing them by hundreds of keV.Plain Language SummaryScientists have wondered how narrow flow channels in space could transport and energize <span class="hlt">electrons</span> enough before the <span class="hlt">electrons</span> escape the channel. They also wondered how narrow, localized magnetic field peaks (and their electric fields) contribute to <span class="hlt">electron</span> energization in comparison to wide, large-scale electromagnetic fields. We show</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000ApJ...545..532W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000ApJ...545..532W"><span>Correlative Aspects of the Solar <span class="hlt">Electron</span> Neutrino <span class="hlt">Flux</span> and Solar Activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilson, Robert M.</p> <p>2000-12-01</p> <p>Between 1970 and 1994, the Homestake Solar Neutrino Detector obtained 108 observations of the solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> (greater than 0.814 MeV). The ``best fit'' values derived from these observations suggest an average daily production rate of about 0.485 37Ar atom per day, a rate equivalent to about 2.6 SNU (solar neutrino units) or about a factor of 3 below the expected rate from the standard solar model. In order to explain, at least, a portion of this discrepancy, many researchers have speculated that the <span class="hlt">flux</span> of solar neutrinos is variable, possibly being correlated with certain markers of the solar cycle (specifically, sunspot number and the Ap index). Indeed, previous studies, on the basis of shorter time intervals or data averaged in particular ways, often found evidence supportive for preferential behavior between the solar neutrino <span class="hlt">flux</span> and solar activity. In this paper, using the larger ``standard data set'' and run-length-adjusted averages, the notion of preferential behavior between solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> and solar activity is reexamined. The results clearly show that no statistically meaningful associations exist between the solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> and any of the usual markers of solar activity, including sunspot number, the Ap index, the Deep River neutron monitor counts (cosmic rays), solar irradiance, and the number or size of solar energetic events (flares).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27256316','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27256316"><span>Reaction <span class="hlt">electronic</span> <span class="hlt">flux</span> and its role in DNA intramolecular proton transfers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Durán, Rocío; Vöhringer-Martinez, Esteban; Toro-Labbé, Alejandro; Herrera, Bárbara</p> <p>2016-06-01</p> <p>Proton transfer reactions present a key step in many biological and chemical processes. Here, we focused on the <span class="hlt">electronic</span> changes in the proton transfer reactions of the four DNA bases. In combination with the previous structural analysis the reaction <span class="hlt">electronic</span> <span class="hlt">flux</span> together with local descriptors as the Hirshfeld-I charges allow us to identify chemical events and rationalize the underlying reaction mechanism. Our results show that imine-enamine in adenine and citosyne, and keto-enol tautomerizations in thymine and guanine have different reaction mechanisms. The former involve net structural rearrangements driven by favoured electrostatic interactions between the proton and the acceptor atom whereas the keto-enol tautomerizations require <span class="hlt">electronic</span> changes reflected in the reaction <span class="hlt">electronic</span> <span class="hlt">flux</span> and changes in the NBO bond orders which favour the proton transfer reaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5340864','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5340864"><span>Integral probability of auroral <span class="hlt">electron</span> <span class="hlt">flux</span> events from SSJ/4 DMSP F9 <span class="hlt">electron</span> measurements. Interim report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hardy, D.A.; Bounar, K.H.</p> <p>1992-05-18</p> <p>A study has been completed to determine the probability of observing different levels of auroral <span class="hlt">electron</span> precipitation both within fixed spatial elements in magnetic local time and corrected geomagnetic latitude, and within spatial elements when the magnetic local time is fixed but the latitude range can be varied. The auroral <span class="hlt">electron</span> precipitation probability is defined for a series of thresholds in <span class="hlt">electron</span> average energy and <span class="hlt">electron</span> energy <span class="hlt">flux</span> as a function of geomagnetic activity. The study provides the capability to determine the probability of observation of an auroral <span class="hlt">electron</span> precipitation event for any specified threshold in average energy, energy <span class="hlt">flux</span>, and level of geomagnetic activity for any location in the auroral region or for any line of sight through the auroral region. The input for the study is one year of data from the SSJ/4 <span class="hlt">electron</span> and proton spectrometer flown on the F9 satellite of the Defense Meteorological Satellite Program (DMSP) comprising approximately 10, 141 hemispheric passes through the auroral region. The binning technique used to determine these probabilities is presented and some results are discussed. The operation of the software package to display the probability results is described. Defense Meteorological Satellite Program (DMSP), Aurora, Precipitating <span class="hlt">electrons</span>, Geomagnetic Kp index, Integral probability.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/451143','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/451143"><span>Modeling of the recycling particle <span class="hlt">flux</span> and <span class="hlt">electron</span> particle transport in the DIII-D tokamak</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baker, D.R.; Jackson, G.L.; Maingi, R.; Owen, L.W.; Porter, G.D.</p> <p>1996-10-01</p> <p>One of the most difficult aspects of performing an equilibrium particle transport analysis in a diverted tokamak is the determination of the particle <span class="hlt">flux</span> which enters the plasma after recycling from the divertor plasma, the divertor target plates or the vessel wall. An approach which has been utilized in the past is to model the edge, scrape-off layer (SOL), and divertor plasma to match measured plasma parameters and then use a neutral transport code to obtain an edge recycling <span class="hlt">flux</span> while trying to match the measured divertor D(x emissivity. Previous simulations were constrained by <span class="hlt">electron</span> density (n{sub e}) and temperature (T{sub e}), ion temperature (T{sub i}) data at the outer midplane, divertor heat <span class="hlt">flux</span> from infrared television cameras, and n{sub e}, T{sub e} and particle <span class="hlt">flux</span> at the target from fixed Langmuir probes, along with the divertor D{sub {alpha}} emissivity. In this paper, we present results of core fueling calculations from the 2-D modeling for ELM-free discharges, constrained by data from the new divertor diagnostics. In addition, we present a simple technique for estimating the recycling <span class="hlt">flux</span> just after the L-H transition and demonstrate how this technique is supported by the detailed modeling. We will show the effect which inaccuracies in the recycling <span class="hlt">flux</span> have on the calculated particle <span class="hlt">flux</span> in the plasma core. For some specific density profiles, it is possible to separate the convective <span class="hlt">flux</span> from the conductive <span class="hlt">flux</span>. The diffusion coefficients obtained show a sharp decrease near a normalized radius of 0.9 indicating the presence of a transport barrier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.5122S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.5122S"><span>RELEC Experiment on board Vernov Satellite: Relativistic <span class="hlt">Electron</span> <span class="hlt">Flux</span> Dynamics in Near-Earth Space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Svertilov, Sergiey</p> <p>2015-04-01</p> <p>The main goal of RELEC mission is study of magnetosphere relativistic <span class="hlt">electron</span> precipitation with it possible acting on the upper atmosphere and ionosphere as well as the monitor observation of radiation and electromagnetic environment in the near-Earth Space. The RELEC set of instruments includes two identical detectors of X- and gamma-rays of high temporal resolution and sensitivity (DRGE-1 & DRGE-2), three axe directed detectors of energetic <span class="hlt">electrons</span> and protons DRGE-3, UV TLE imager MTEL, UV detector DUV, low-frequency analyser LFA, radio-frequency analyser RFA, module of <span class="hlt">electronics</span> intended for commands and data collection BE. The small satellite now named Vernov with RELEC instruments was successfully launched July, 8 2014. The mission orbit is solar-synchronous with apogee 830 km, perigee 640 km, inclination 98.4o and orbital period about 100 min. The total data output is about 1.2 Gbyte per day. The <span class="hlt">fluxes</span> and spectra of <span class="hlt">electrons</span> in the wide energy range from 0.2 to 15 MeV are measured with the use of three detectors with axe normally directed to each other: to the local zenith, opposite to the satellite velocity vector and along the direction added two previous to the Cartesian system. Due to such detector system it is possible to estimate the <span class="hlt">electron</span> <span class="hlt">flux</span> anisotropy. The wide dynamical range from ~1 up to 104 part/cm2s and fine time resolution (~10 mcs) allows observations of trapped, quasi-trapped and precipitated <span class="hlt">electron</span> <span class="hlt">flux</span> and spectral variations in different areas in the near-Earth space including low L-shells. Comparative analysis of <span class="hlt">electron</span> <span class="hlt">fluxes</span> measured by RELEC with experimental data on <span class="hlt">electron</span> detection in the experiments on board the spacecraft Electro-L with geostationary orbit, and Meteor-M2 with 800 km altitude circular polar orbit similar to Vernov allows to reconstruct the energetic <span class="hlt">electron</span> spatial distribution in the near-Earth space. A comparison will be held for periods of moderate geomagnetic disturbances of August 26</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JNuM..455..382L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JNuM..455..382L"><span>Tungsten joining with copper alloy and its <span class="hlt">high</span> <span class="hlt">heat</span> load performance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Xiang; Lian, Youyun; Chen, Lei; Cheng, Zengkui; Chen, Jiming; Duan, Xuru; Song, Jioupeng; Yu, Yang</p> <p>2014-12-01</p> <p>W-CuCrZr joining technology by using low activation Cu-Mn filler metal was developed at Southwestern Institute of Physics (SWIP) for the manufacturing of divertor components of fusion experiment devices. In addition, a fast W coating technology by chemical vapor deposition (CVD) was also developed and CVD-W/CuCrZr and CVD-W/C mockups with a W coating thickness of 2 mm were prepared. In order to assess their <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> (HHF) performances, a 60 kW <span class="hlt">Electron</span>-beam Material testing Scenario (EMS-60) equipped with a 150 keV <span class="hlt">electron</span> beam welding gun was constructed at SWIP. Experimental results indicated that brazed W/CuCrZr mockups can withstand 8 MW/m2 heat <span class="hlt">flux</span> for 1000 cycles without visible damages and CVD-W/CuCrZr mockups with W-Cu gradient interface can survive 1000 cycles under 11 MW/m2 heat <span class="hlt">flux</span>. An ultrasonic inspection method for non-destructive tests (NDT) of brazed W/CuCrZr mockups was established and 2 mm defect can be detected. Infinite element analysis and heat load tests indicated that 5 mm defect had less noticeable influence on the heat transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24b2109I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24b2109I"><span>Transport coefficients and heat <span class="hlt">fluxes</span> in non-equilibrium high-temperature flows with <span class="hlt">electronic</span> excitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Istomin, V. A.; Kustova, E. V.</p> <p>2017-02-01</p> <p>The influence of <span class="hlt">electronic</span> excitation on transport processes in non-equilibrium high-temperature ionized mixture flows is studied. Two five-component mixtures, N 2 / N2 + / N / N + / e - and O 2 / O2 + / O / O + / e - , are considered taking into account the <span class="hlt">electronic</span> degrees of freedom for atomic species as well as the rotational-vibrational-<span class="hlt">electronic</span> degrees of freedom for molecular species, both neutral and ionized. Using the modified Chapman-Enskog method, the transport coefficients (thermal conductivity, shear viscosity and bulk viscosity, diffusion and thermal diffusion) are calculated in the temperature range 500-50 000 K. Thermal conductivity and bulk viscosity coefficients are strongly affected by <span class="hlt">electronic</span> states, especially for neutral atomic species. Shear viscosity, diffusion, and thermal diffusion coefficients are not sensible to <span class="hlt">electronic</span> excitation if the size of excited states is assumed to be constant. The limits of applicability for the Stokes relation are discussed; at high temperatures, this relation is violated not only for molecular species but also for <span class="hlt">electronically</span> excited atomic gases. Two test cases of strongly non-equilibrium flows behind plane shock waves corresponding to the spacecraft re-entry (Hermes and Fire II) are simulated numerically. Fluid-dynamic variables and heat <span class="hlt">fluxes</span> are evaluated in gases with <span class="hlt">electronic</span> excitation. In inviscid flows without chemical-radiative coupling, the flow-field is weakly affected by <span class="hlt">electronic</span> states; however, in viscous flows, their influence can be more important, in particular, on the convective heat <span class="hlt">flux</span>. The contribution of different dissipative processes to the heat transfer is evaluated as well as the effect of reaction rate coefficients. The competition of diffusion and heat conduction processes reduces the overall effect of <span class="hlt">electronic</span> excitation on the convective heating, especially for the Fire II test case. It is shown that reliable models of chemical reaction rates are of great</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930049688&hterms=Quantitative+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DQuantitative%2BAnalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930049688&hterms=Quantitative+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DQuantitative%2BAnalysis"><span>Quantitative analysis of bidirectional <span class="hlt">electron</span> <span class="hlt">fluxes</span> within coronal mass ejections at 1 AU</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Phillips, J. L.; Gosling, J. T.; Mccomas, D. J.; Bame, S. J.; Feldman, W. C.</p> <p>1992-01-01</p> <p>The solar wind <span class="hlt">electron</span> heat <span class="hlt">flux</span> is carried primarily by suprathermal <span class="hlt">electrons</span> beamed antisunward along the interplanetary magnetic field. However, analysis of <span class="hlt">electron</span> observations at 1 AU has shown that counterstreaming <span class="hlt">electron</span> beams, suggesting closed magnetic structures, prevail within coronal mass ejections (CMEs). These structures might be magnetic 'tongues', magnetically detached plasmoids, or complex <span class="hlt">flux</span> ropes. Here we show results of analysis of ISEE-3 observations within 39 CMEs, including the asymmetry between the two beams, its control by magnetic field orientation, and the variation of the <span class="hlt">electron</span> distributions as CMEs convect past the spacecraft. We find that some CMEs are strongly asymmetric, with the antisunward beam generally dominant, while others contain nearly symmetric beams. The beam asymmetries, and the magnetic field orientations, exhibit characteristic trends as CMEs pass over the spacecraft. We present an example of a distinctive 'strahl-on-strahl' distribution, suggesting continued magnetic connection to the corona, in which a narrow antisunward beam is superimposed on a broader beam. Our results favor continuing magnetic connection to the Sun in a tongue or <span class="hlt">flux</span> rope geometry rather than a fully detached plasmoid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991STIN...9216965P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991STIN...9216965P"><span>Quantitative analysis of bidirectional <span class="hlt">electron</span> <span class="hlt">fluxes</span> within coronal mass ejections at 1 AU</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, J. L.; Gosling, J. T.; McComas, D. J.; Bame, S. J.; Feldman, W. C.</p> <p></p> <p>The solar wind <span class="hlt">electron</span> heat <span class="hlt">flux</span> is carried primarily by suprathermal 'halo' <span class="hlt">electrons</span> beamed antisunward along the interplanetary magnetic field (IMF), indicating magnetic connection to the Sun only in one direction. However, <span class="hlt">electron</span> observations at 1 AU show that counterstreaming halo beams, suggesting closed magnetic structures, prevail within coronal mass ejections (CME's). These structures might be magnetic 'tongues', tied to the Sun at both ends, magnetically detached plasmoids, or complex <span class="hlt">flux</span> rope structures. Here, we present first results of analysis of ISEE-3 observations within 39 CME's, including the asymmetry between the counterstreaming beams and its control by the IMF orientation, and the variation of the <span class="hlt">electron</span> distributions as CME's convect past the spacecraft. We find that some CME's contain nearly symmetric <span class="hlt">electron</span> beams, while others are strongly asymmetric, and that the antisunward beam is generally dominant. The more nearly radial the IMF, the greater the asymmetry between outward and inward beams. We present an example of a distinctive 'strahl-on-strahl' distribution, suggesting continued magnetic connection to the corona, in which a narrow antisunward beam is superimposed on a broader beam. Taken as a whole, our results appear to favor a tongue or <span class="hlt">flux</span> rope scenario rather than a fully detached plasmoid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20643911','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20643911"><span>The role of <span class="hlt">electron</span> heat <span class="hlt">flux</span> in guide-field magnetic reconnection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hesse, Michael; Kuznetsova, Masha; Birn, Joachim</p> <p>2004-12-01</p> <p>A combination of analytical theory and particle-in-cell simulations are employed in order to investigate the <span class="hlt">electron</span> dynamics near and at the site of guide field magnetic reconnection. A detailed analysis of the contributions to the reconnection electric field shows that both bulk inertia and pressure-based quasiviscous processes are important for the <span class="hlt">electrons</span>. Analytic scaling demonstrates that conventional approximations for the <span class="hlt">electron</span> pressure tensor behavior in the dissipation region fail, and that heat <span class="hlt">flux</span> contributions need to be accounted for. Based on the evolution equation of the heat <span class="hlt">flux</span> three tensor, which is derived in this paper, an approximate form of the relevant heat <span class="hlt">flux</span> contributions to the pressure tensor is developed, which reproduces the numerical modeling result reasonably well. Based on this approximation, it is possible to develop a scaling of the <span class="hlt">electron</span> current layer in the central dissipation region. It is shown that the pressure tensor contributions become important at the scale length defined by the <span class="hlt">electron</span> Larmor radius in the guide magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1291235-nonstorm-time-dropout-radiation-belt-electron-fluxes-september','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1291235-nonstorm-time-dropout-radiation-belt-electron-fluxes-september"><span>Nonstorm time dropout of radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 24 September 2013</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; ...</p> <p>2016-07-01</p> <p>Radiation belt <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ αe ≤ 180°). STEERB simulations show that the relativistic <span class="hlt">electron</span> loss in the region L = 4.5–6.0 was primarily caused bymore » the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PPNL...13.1006S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PPNL...13.1006S"><span>Acceleration of deuterons from laser plasma in direct pulsed <span class="hlt">electron</span> <span class="hlt">fluxes</span> for generation of neutrons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Shatokhin, V. L.</p> <p>2016-12-01</p> <p>We report the results of experiments in which laser plasma deuterons are accelerated toward beryllium and deuterated polyethylene targets in a drift tube by means of a direct pulsed <span class="hlt">flux</span> of <span class="hlt">electrons</span> accelerated to maximum energy of 250 keV. Neutrons produced as a result of the interaction of deuterons with the targets are detected. The yield of neutrons in some of the experimental series reaches 106 n/pulse. Using a pulsed magnetic field synchronized with the generation of laser plasma is proposed for increasing the neutron yield as a result of <span class="hlt">electron</span> <span class="hlt">flux</span> compression. This magnetic field in the drift region of <span class="hlt">electrons</span> is created by a spiral coil of conical shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1291235','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1291235"><span>Nonstorm time dropout of radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 24 September 2013</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; Funsten, Herbert O.; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Baker, D. N.; Blake, J. B.; Wygant, J. R.</p> <p>2016-07-01</p> <p>Radiation belt <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (<i>L</i> > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ α<sub>e</sub> ≤ 180°). STEERB simulations show that the relativistic <span class="hlt">electron</span> loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.6400S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.6400S"><span>Nonstorm time dropout of radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 24 September 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Zhenpeng; Gao, Zhonglei; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.; Wygant, J. R.</p> <p>2016-07-01</p> <p>Radiation belt <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (˜500 keV to several MeV) and equatorial pitch angles (0°≤αe≤180°). STEERB simulations show that the relativistic <span class="hlt">electron</span> loss in the region L = 4.5-6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1291235','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1291235"><span>Nonstorm time dropout of radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 24 September 2013</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; Funsten, Herbert O.; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Baker, D. N.; Blake, J. B.; Wygant, J. R.</p> <p>2016-07-01</p> <p>Radiation belt <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (<i>L</i> > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ α<sub>e</sub> ≤ 180°). STEERB simulations show that the relativistic <span class="hlt">electron</span> loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..224G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..224G"><span>The Mars aurora: UV detections and in situ <span class="hlt">electron</span> <span class="hlt">flux</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gérard, J.-C.; Soret, L.; Lundin, R.; Libert, L.; Stiepen, A.; Radioti, A.; Bertaux, J.-L.; Shematovich, V. I.; Bisikalo, D.</p> <p>2015-10-01</p> <p>A detailed search through the database of the SPICAM instrument on board Mars Express made it possible to identify 16 signatures of the CO Cameron and CO2+ doublet auroral emissions. These auroral UV signatures are all located in the southern hemisphere in the vicinity of the statistical boundary between open and closed field lines. The energy spectrum of the energetic <span class="hlt">electrons</span> was simultaneously measured by ASPERA-3/ELS at higher altitude. The UV aurora is generally shifted from the region of enhanced downward <span class="hlt">electron</span> energy <span class="hlt">flux</span> by a few to several tens of degrees of latitude, suggesting that precipitation occurs in magnetic cusp like structures along inclined magnetic field lines. The ultraviolet brightness shows no proportionality with the <span class="hlt">electron</span> <span class="hlt">flux</span> measured at the spacecraft altitude. The Mars aurora appears as a sporadic short-lived feature. Results of Monte Carlo simulations will be compared with the observed brightness of the Cameron and CO2+ bands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CP....482..146J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CP....482..146J"><span>Quantum control of <span class="hlt">electronic</span> <span class="hlt">fluxes</span> during adiabatic attosecond charge migration in degenerate superposition states of benzene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jia, Dongming; Manz, Jörn; Paulus, Beate; Pohl, Vincent; Tremblay, Jean Christophe; Yang, Yonggang</p> <p>2017-01-01</p> <p>We design four linearly x- and y-polarized as well as circularly right (+) and left (-) polarized, resonant π / 2 -laser pulses that prepare the model benzene molecule in four different degenerate superposition states. These consist of equal (0.5) populations of the <span class="hlt">electronic</span> ground state S0 (1A1g) plus one of four degenerate excited states, all of them accessible by dipole-allowed transitions. Specifically, for the molecule aligned in the xy-plane, these excited states include different complex-valued linear combinations of the 1E1u,x and 1E1u,y degenerate states. As a consequence, the laser pulses induce four different types of periodic adiabatic attosecond (as) charge migrations (AACM) in benzene, all with the same period, 504 as, but with four different types of angular <span class="hlt">fluxes</span>. One of the characteristic differences of these <span class="hlt">fluxes</span> are the two angles for zero <span class="hlt">fluxes</span>, which appear as the instantaneous angular positions of the "source" and "sink" of two equivalent, or nearly equivalent branches of the <span class="hlt">fluxes</span> which flow in pincer-type patterns from one molecular site (the "source") to the opposite one (the "sink"). These angles of zero <span class="hlt">fluxes</span> are either fixed at the positions of two opposite carbon nuclei in the yz-symmetry plane, or at the centers of two opposite carbon-carbon bonds in the xz-symmetry plane, or the angles of zero <span class="hlt">fluxes</span> rotate in angular forward (+) or backward (-) directions, respectively. As a resume, our quantum model simulations demonstrate quantum control of the <span class="hlt">electronic</span> <span class="hlt">fluxes</span> during AACM in degenerate superposition states, in the attosecond time domain, with the laser polarization as the key knob for control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA624807','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA624807"><span><span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Surface Coke Deposition and Removal Assessment</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-01-01</p> <p>deposited over the course of multiple missions. Therefore, there is a need for a method to survey coke layer thicknesses and locations in the cooling...thin coke layers makes this a difficult and challenging problem. Reaction Systems, Inc. has developed a low temperature oxidation method that can...rapidly remove the coke layers in the cooling channels and at the same time map their location. We demonstrated this technique in a recent SBIR Phase II</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10135706','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10135706"><span>Structural materials for <span class="hlt">high-heat</span> <span class="hlt">flux</span> applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rybin, V.V.; Smith, D.L.</p> <p>1991-12-31</p> <p>The structural materials for the ITER, (International Thermonuclear Experimental Reactor) divertor must perform reliably under complex and diverse operating requirements. Only a limited number of materials offer a potential for meeting these requirements for the wide temperature range of interest. The candidate materials considered in the ITER design activity include copper, molybdenum, niobium alloys. Molybdenum alloys being considered include dilute alloys of the TZM type and the Mo-Re system. Niobium alloys under consideration include Nb-V-Zr and Nb-Zr systems. Copper alloys being considered include precipitation strengthened alloys of the Glidcop and MAGT type, alloys of Cu-Mo system and dispersion hardened bronzes. The projected operating conditions for the ITER divertor and the criteria for evaluating the candidate materials are reviewed. This paper summarizes the data base and presents recent experimental results on these candidate divertor structural alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5604984','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5604984"><span>Structural materials for <span class="hlt">high-heat</span> <span class="hlt">flux</span> applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rybin, V.V. ); Smith, D.L. )</p> <p>1991-01-01</p> <p>The structural materials for the ITER, (International Thermonuclear Experimental Reactor) divertor must perform reliably under complex and diverse operating requirements. Only a limited number of materials offer a potential for meeting these requirements for the wide temperature range of interest. The candidate materials considered in the ITER design activity include copper, molybdenum, niobium alloys. Molybdenum alloys being considered include dilute alloys of the TZM type and the Mo-Re system. Niobium alloys under consideration include Nb-V-Zr and Nb-Zr systems. Copper alloys being considered include precipitation strengthened alloys of the Glidcop and MAGT type, alloys of Cu-Mo system and dispersion hardened bronzes. The projected operating conditions for the ITER divertor and the criteria for evaluating the candidate materials are reviewed. This paper summarizes the data base and presents recent experimental results on these candidate divertor structural alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9236E..1AV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9236E..1AV"><span>Do <span class="hlt">electron</span> <span class="hlt">flux</span> and solar x-ray in juxtaposition prior a seismic event make signature?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verma, Umesh Prasad; Sinha, Madhurendra Nath</p> <p>2014-09-01</p> <p>Variation in the trend of <span class="hlt">electron</span> <span class="hlt">flux</span> graph in the ionosphere on the global map is common with respect to proton <span class="hlt">flux</span> variation in inverse manner seen on diurnal basis. Continuous observation connected with the NOAA , IPS and SOHO satellite respectively of USA, Australia ,Japan and India have revealed the facts remarkably peculiar and interesting trend other than usual graph of <span class="hlt">Electron</span> <span class="hlt">flux</span> and solar x-ray decrease in peak level immediate prior a seismic event. An observation recorded in juxtaposition the trend of correlation establishes this fact. This typify the events like Iran 14th April, China 17th April 2013, with 7.8 and 7.3 MW, New Zealand 6.8 MW on 16th August 2013, Pakistan 7.8 Mw and 6.8 Mw respectively on25th September, and 26th September'2013 are the supportive illustrations to the concluding concepts. The trend is also observed during the solar coronal mass ejection event. Events occur deceptively quite similar to the pre seismicity. Its diagnostic distinction can be made with the solar data available by SWPC (Australia) forecasting for solar prominences data prediction and forecasting tool. Most of the seismic phenomena are the diagnostic preseismic phenomena as the <span class="hlt">electron</span> <span class="hlt">flux</span> anomaly mechanism and principle clarify on the basis of fundamental laws of electrostatics and Maxwell equation of electromagnetic wave theory. This may prove a precursory tool in the seismic event forecasting and prediction technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19269096','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19269096"><span>Imaging <span class="hlt">flux</span> vortices in type II superconductors with a commercial transmission <span class="hlt">electron</span> microscope.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Loudon, J C; Midgley, P A</p> <p>2009-05-01</p> <p><span class="hlt">Flux</span> vortices in superconductors can be imaged using transmission <span class="hlt">electron</span> microscopy because the <span class="hlt">electron</span> beam is deflected by the magnetic <span class="hlt">flux</span> associated with the vortices. This technique has a better spatial and temporal resolution than many other imaging techniques and is sensitive to the magnetic <span class="hlt">flux</span> density within each vortex, not simply the fields at the sample surface. Despite these advantages, only two groups have successfully employed the technique using specially adapted instruments. Here we demonstrate that vortices can be imaged with a modern, commercial transmission <span class="hlt">electron</span> microscope operating at 300kV equipped with a field emission gun, Lorentz lens and a liquid helium cooled sample holder. We introduce superconductivity for non-specialists and discuss techniques for simulating and optimising images of <span class="hlt">flux</span> vortices. Sample preparation is discussed in detail as the main difficulty with the technique is the requirement for samples with very large (>10microm), flat areas so that the image is not dominated by diffraction contrast. We have imaged vortices in superconducting Bi(2)Sr(2)CaCu(2)O(8-delta) and use correlation functions to investigate the ordered arrangements they adopt as a function of applied magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000074664&hterms=neutrino&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dneutrino','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000074664&hterms=neutrino&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dneutrino"><span>Correlative Aspects of the Solar <span class="hlt">Electron</span> Neutrino <span class="hlt">Flux</span> and Solar Activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Robert M.</p> <p>2000-01-01</p> <p>Between 1970 and 1994, the Homestake Solar Neutrino Detector obtained 108 observations of the solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> (less than 0.814 MeV). The "best fit" values derived from these observations suggest an average daily production rate of about 0.485 Ar-37 atom per day, a rate equivalent to about 2.6 SNU (solar neutrino units) or about a factor of 3 below the expected rate from the standard solar model. In order to explain, at least, a portion of this discrepancy, some researchers have speculated that the <span class="hlt">flux</span> of solar neutrinos is variable, possibly being correlated with various markers of the solar cycle (e.g., sunspot number, the Ap index, etc.). In this paper, using the larger "standard data set," the issue of correlative behavior between solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> and solar activity is re-examined. The results presented here clearly indicate that no statistically significant association exists between any of the usual markers of solar activity and the solar <span class="hlt">electron</span> neutrino <span class="hlt">flux</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SpWea..15..917M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SpWea..15..917M"><span>Extreme relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the Earth's outer radiation belt: Analysis of INTEGRAL IREM data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meredith, Nigel P.; Horne, Richard B.; Sandberg, Ingmar; Papadimitriou, Constantinos; Evans, Hugh D. R.</p> <p>2017-07-01</p> <p>Relativistic <span class="hlt">electrons</span> (E > 500 keV) cause internal charging and are an important space weather hazard. To assess the vulnerability of the satellite fleet to these so-called "killer" <span class="hlt">electrons</span>, it is essential to estimate reasonable worst cases, and, in particular, to estimate the <span class="hlt">flux</span> levels that may be reached once in 10 and once in 100 years. In this study we perform an extreme value analysis of the relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the Earth's outer radiation belt as a function of energy and L∗. We use data from the Radiation Environment Monitor (IREM) on board the International Gamma Ray Astrophysical Laboratory (INTEGRAL) spacecraft from 17 October 2002 to 31 December 2016. The 1 in 10 year <span class="hlt">flux</span> at L∗=4.5, representative of equatorial medium Earth orbit, decreases with increasing energy ranging from 1.36 × 107 cm-2 s-1 sr-1 MeV-1 at E = 0.69 MeV to 5.34 × 105 cm-2 s-1 sr-1 MeV-1 at E = 2.05 MeV. The 1 in 100 year <span class="hlt">flux</span> at L∗=4.5 is generally a factor of 1.1 to 1.2 larger than the corresponding 1 in 10 year <span class="hlt">flux</span>. The 1 in 10 year <span class="hlt">flux</span> at L∗=6.0, representative of geosynchronous orbit, decreases with increasing energy ranging from 4.35 × 106 cm-2 s-1 sr-1 MeV-1 at E = 0.69 MeV to 1.16 × 105 cm-2 s-1 sr-1 MeV-1 at E = 2.05 MeV. The 1 in 100 year <span class="hlt">flux</span> at L∗=6.0 is generally a factor of 1.1 to 1.4 larger than the corresponding 1 in 10 year <span class="hlt">flux</span>. The ratio of the 1 in 10 year <span class="hlt">flux</span> at L∗=4.5 to that at L∗=6.0 increases with increasing energy ranging from 3.1 at E = 0.69 MeV to 4.6 at E = 2.05 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM51A2518S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM51A2518S"><span>Calibrating MMS <span class="hlt">Electron</span> Drift Instrument (EDI) Ambient <span class="hlt">Electron</span> <span class="hlt">Flux</span> Measurements and Characterizing 3D Electric Field Signatures of Magnetic Reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shuster, J. R.; Torbert, R. B.; Vaith, H.; Argall, M. R.; Li, G.; Chen, L. J.; Ergun, R. E.; Lindqvist, P. A.; Marklund, G. T.; Khotyaintsev, Y. V.; Russell, C. T.; Magnes, W.; Le Contel, O.; Pollock, C. J.; Giles, B. L.</p> <p>2015-12-01</p> <p>The <span class="hlt">electron</span> drift instruments (EDIs) onboard each MMS spacecraft are designed with large geometric factors (~0.01cm2 str) to facilitate detection of weak (~100 nA) <span class="hlt">electron</span> beams fired and received by the two gun-detector units (GDUs) when EDI is in its "electric field mode" to determine the local electric and magnetic fields. A consequence of the large geometric factor is that "ambient mode" <span class="hlt">electron</span> <span class="hlt">flux</span> measurements (500 eV <span class="hlt">electrons</span> having 0°, 90°, or 180° pitch angle) can vary depending on the orientation of the EDI instrument with respect to the magnetic field, a nonphysical effect that requires a correction. Here, we present determinations of the θ- and ø-dependent correction factors for the eight EDI GDUs, where θ (ø) is the polar (azimuthal) angle between the GDU symmetry axis and the local magnetic field direction, and compare the corrected <span class="hlt">fluxes</span> with those measured by the fast plasma instrument (FPI). Using these corrected, high time resolution (~1,000 samples per second) ambient <span class="hlt">electron</span> <span class="hlt">fluxes</span>, combined with the unprecedentedly high resolution 3D electric field measurements taken by the spin-plane and axial double probes (SDP and ADP), we are equipped to accurately detect <span class="hlt">electron</span>-scale current layers and electric field waves associated with the non-Maxwellian (anisotropic and agyrotropic) particle distribution functions predicted to exist in the reconnection diffusion region. We compare initial observations of the diffusion region with distributions and wave analysis from PIC simulations of asymmetric reconnection applicable for modeling reconnection at the Earth's magnetopause, where MMS will begin Science Phase 1 as of September 1, 2015.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMSM41C0583N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMSM41C0583N"><span>Mechanisms of the outer radiation belt <span class="hlt">electron</span> <span class="hlt">flux</span> variation during magnetic storms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, M.; Obara, T.; Koshiishi, H.; Koga, K.; Matsumoto, H.; Goka, T.</p> <p>2003-12-01</p> <p>We have investigated variations of the energetic <span class="hlt">electron</span> <span class="hlt">flux</span> (> 0.4 MeV) and the magnetic field in the outer radiation belt obtained from the Standard DOse Monitor (SDOM) and the MAgnetoMeter (MAM) of the Space Environment Data Acquisition equipment (SEDA) onboard Tsubasa (Mission Demonstration Test Satellite (MDS)-1). Since Tsubasa operates in geostationary transfer orbit (GTO) with an orbital period of 10 hours and an inclination of 28.5 degrees, it has provided a rare opportunity for directly observing near-equatorial radiation belt plasma particles and the magnetic field during magnetic storms. The decreases of the energetic <span class="hlt">electron</span> <span class="hlt">flux</span> during the main phase of the magnetic storms, and the subsequent recoveries and enhancements during the recovery phase in the outer radiation belt are linked respectively to typical variations of the magnetic field. At the moment that the outer radiation belt <span class="hlt">flux</span> sharply drops during the main phase of the 17 April 2002 magnetic storm, the butterfly distribution is observed at L=5 and the magnetic equator where the magnitude of magnetic field is much smaller than the IGRF model. Calculating the drift motions of the energetic <span class="hlt">electrons</span> in the Tyganenko 2001 magnetospheric magnetic field model, shows that the drift-shell splitting mechanism could generate the butterfly distribution due to loss of the near-equatorially mirroring <span class="hlt">electrons</span> through dayside magnetopause boundary. We evaluate roles and contributions of the other possible mechanisms to explain the <span class="hlt">flux</span> decreases. We discuss the three-dimensional field configuration in the magnetopause to compare with the low earth orbital observation of the outer radiation belt <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSMSM51A..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSMSM51A..06M"><span>Effects of <span class="hlt">Electron</span> Pressure Tensor and Heat <span class="hlt">Flux</span> on Magnetic Reconnection from PIC and Hybrid Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Main, D. S.; Yin, L.; Winske, D.</p> <p>2007-05-01</p> <p>Thin current sheets lead to rapid magnetic reconnection and conversion of magnetic energy to particle energy. Two-dimensional (2D) simulations performed with different physical models and an initial planar current sheet (the GEM and Newton challenge studies) showed similar fast reconnection rates. In this paper, we discuss in detail simulations of 2D reconnection carried out with a full particle-in-cell (PIC) code and a hybrid (particle ions, massless fluid <span class="hlt">electrons</span>) code that was part of the Challenge study (Birn et al., GRL, 32, L06105, 2005). In the hybrid code, the <span class="hlt">electron</span> model contains the full <span class="hlt">electron</span> pressure tensor in the <span class="hlt">electron</span> momentum equation to break the frozen-in condition. We compare quantitatively the effects of the <span class="hlt">electron</span> pressure tensor in the two types of simulations and show both how they evolve in time and where in the thin current sheet the <span class="hlt">electron</span> off-diagonal pressure tensor terms become important. In addition, we make quantitative comparisons between reconnection rates and flow velocities obtained from the two codes. It is still an open question how best to evolve the pressure tensor and include the effects of <span class="hlt">electron</span> heat <span class="hlt">flux</span> in the hybrid model. The evolution equation for the pressure tensor has several terms and the effects of some of these terms on the reconnection dynamics will be examined. In particular, PIC simulations will be used to examine the role of heat <span class="hlt">flux</span> in reconnection events in the absence of a guide field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023417','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023417"><span>On the Relationship Between High Speed Solar Wind Streams and Radiation Belt <span class="hlt">Electron</span> <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zheng, Yihua</p> <p>2011-01-01</p> <p>Both past and recent research results indicate that solar wind speed has a close connection to radiation belt <span class="hlt">electron</span> <span class="hlt">fluxes</span> [e.g., Paulikas and Blake, 1979; Reeves et aI., 2011]: a higher solar wind speed is often associated with a higher level of radiation <span class="hlt">electron</span> <span class="hlt">fluxes</span>. But the relationship can be very complex [Reeves et aI., 2011]. The study presented here provides further corroboration of this viewpoint by emphasizing the importance of a global perspective and time history. We find that all the events during years 2010 and 2011 where the >0.8 MeV integral <span class="hlt">electron</span> <span class="hlt">flux</span> exceeds 10(exp 5) particles/sq cm/sr/s (pfu) at GEO orbit are associated with the high speed streams (HSS) following the onset of the Stream Interaction Region (SIR), with most of them belonging to the long-lasting Corotating Interaction Region (CIR). Our preliminary results indicate that during HSS events, a maximum speed of 700 km/s and above is a sufficient but not necessary condition for the > 0.8 MeV <span class="hlt">electron</span> <span class="hlt">flux</span> to reach 10(exp 5) pfu. But in the exception cases of HSS events where the <span class="hlt">electron</span> <span class="hlt">flux</span> level exceeds the 10(exp 5) pfu value but the maximum solar wind speed is less than 700 km/s, a prior impact can be noted either from a CME or a transient SIR within 3-4 days before the arrival of the HSS - stressing the importance of time history. Through superposed epoch analysis and studies providing comparisons with the CME events and the HSS events where the <span class="hlt">flux</span> level fails to reach the 10(exp 5) pfu, we will present the quantitative assessment of behaviors and relationships of various quantities, such as the time it takes to reach the <span class="hlt">flux</span> threshold value from the stream interface and its dependence on different physical parameters (e.g., duration of the HSS event, its maximum or average of the solar wind speed, IMF Bz, Kp). The ultimate goal is to apply what is derived to space weather forecasting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740035641&hterms=volt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvolt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740035641&hterms=volt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvolt"><span>Observations of the nighttime <span class="hlt">electron</span> volt range <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the equatorial region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, B. C. N.; Singh, R.; Maier, E. J.</p> <p>1974-01-01</p> <p>The importance of some of the features observed among the nighttime equatorial data of Explorer 31 is discussed with respect to the nighttime thermal structure of the topside ionosphere. The very short-lived photoelectrons being absent, the nighttime measurements represent the background <span class="hlt">flux</span> due to magnetospheric particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740035641&hterms=volt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dvolt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740035641&hterms=volt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dvolt"><span>Observations of the nighttime <span class="hlt">electron</span> volt range <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the equatorial region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, B. C. N.; Singh, R.; Maier, E. J.</p> <p>1974-01-01</p> <p>The importance of some of the features observed among the nighttime equatorial data of Explorer 31 is discussed with respect to the nighttime thermal structure of the topside ionosphere. The very short-lived photoelectrons being absent, the nighttime measurements represent the background <span class="hlt">flux</span> due to magnetospheric particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM41E..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM41E..01M"><span>High time-resolution <span class="hlt">electron</span> energy and <span class="hlt">flux</span> estimates inside regions of flickering and pulsating aurora</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michell, R.; Samara, M.; Grubbs, G. A., II</p> <p>2016-12-01</p> <p>The temporal fluctuations within the aurora can vary over vastly different timescales, indicating different generation mechanisms. Fluctuating aurora best describes two main types of aurora, commonly referred to as flickering aurora and pulsating aurora. These two types of aurora contain temporal fluctuations that vary from being periodic to semi-periodic to nearly random and covering timescales of 20 Hz to minutes. High-resolution multi-spectral auroral imaging is used to compute emission line ratios that can be used in combination with <span class="hlt">electron</span> transport modeling in order to estimate the average energy and total energy <span class="hlt">flux</span> of the precipitating <span class="hlt">electrons</span>. The auroral imaging used here was recorded at a rate of 40 frames per second, with energy and <span class="hlt">flux</span> estimates made at each frame, enabling unprecedented time resolution for examining the precipitating <span class="hlt">electron</span> characteristics within these fluctuations. The variations in the total energy <span class="hlt">flux</span> and average energy of the precipitating <span class="hlt">electrons</span> will be compared to the phase of the optical auroral cycle, in order to gain insight into the generation processes creating the fluctuating cycles. The emphasis of this talk will be on using these techniques to gain insight into the outstanding questions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820047461&hterms=Electron+Transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DElectron%2BTransfer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820047461&hterms=Electron+Transfer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DElectron%2BTransfer"><span>Energetic protons, alpha particles, and <span class="hlt">electrons</span> in magnetic <span class="hlt">flux</span> transfer events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scholer, M.; Hovestadt, D.; Ipavich, F. M.; Gloeckler, G.</p> <p>1982-01-01</p> <p>Energetic proton, alpha particle, and <span class="hlt">electron</span> data are presented for two magnetopause crossings, which show magnetic field signatures characteristic of <span class="hlt">flux</span> transfer events (FTEs). Energetic proton and alpha particles are observed streaming along the magnetic field within the magnetosheath in all events showing magnetic signatures characteristic of the FTEs. <span class="hlt">Flux</span> ratios as high as about 180 parallel and antiparallel to the magnetic field are observed, which means that ions of about 30 keV per charge are at times streaming almost scatter-free from the magnetopause into the magnetosheath. Energetic ion bursts with signatures equal to those observed in FTEs are reduced by more than an order of magnitude as compared to the trapped particle <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992PhDT.......136G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992PhDT.......136G"><span><span class="hlt">Flux</span> Pinning Phenomena in <span class="hlt">Electron</span> Irradiated Yttrium BARIUM(2) COPPER(3) OXYGEN(7-DELTA) Single Crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giapintzakis, John Konstantinos</p> <p>1992-01-01</p> <p>It has been shown that 1 MeV <span class="hlt">electron</span> irradiation to a typical dose Phi~ 1times 10^{19} cm^{ -2} results in an enhancement of the critical current density in twinned and untwinned YBa_2 Cu_3O_{7 -delta} single crystals. Values up to two times the preirradiation J_{c} at 10 K and 1 T are observed. The J _{c} enhancement is accompanied by a dramatic increase of the irreversibility field. A threshold incident <span class="hlt">electron</span> energy (E_{ t}~ 0.5 MeV) is found above which <span class="hlt">flux</span> pinning enhancement is observed. The data indicated that the <span class="hlt">electron</span> radiation-induced defects are effective pinning centers only for the orientation H parallel c-axis. In-situ TEM studies in the HVEM suggest that the pinning centers must be smaller than 20 A. A comparison of the <span class="hlt">electron</span> irradiation results with those of proton irradiation experiments indicate a lower magnitude of enhancement of J_{c} at 10 K and 2 T for the <span class="hlt">electron</span> case. The probable explanation is the difference in the energy spectra of the PKAs produced by the two types of irradiation. GdBa_2Cu_3O_{7-delta } and EuBa_2Cu_3O _{7-delta} single crystals irradiated with 0.6 MeV <span class="hlt">electrons</span> displayed similar <span class="hlt">flux</span> pinning enhancements as YBa_2Cu _3O_{7-delta} crystals, indicating that Y displacements are not primary <span class="hlt">flux</span> pinners. The evidence from annealing studies suggests that the primary pinning center produced by the <span class="hlt">electron</span> irradiation is not associated with the oxygen in the Cu-O chains. Instead, a consistent interpretation of the data suggests that the primary pinning defect is most likely based on the displacement of a copper atom from the CuO_2 plane. In order to account for the complete enhancement of J_{c} other pinning mechanisms aside from point defects, such as small point defect clusters, should be considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23415834','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23415834"><span>Low-<span class="hlt">flux</span> <span class="hlt">electron</span> diffraction study for the intercellular lipid organization on a human corneocyte.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakazawa, Hiromitsu; Imai, Tomohiro; Hatta, Ichiro; Sakai, Shingo; Inoue, Shintaro; Kato, Satoru</p> <p>2013-06-01</p> <p>Human skin stratum corneum (SC) structures were investigated by <span class="hlt">electron</span> diffraction (ED) with a very low-<span class="hlt">flux</span> <span class="hlt">electron</span> beam with the help of high-sensitivity detectors, the imaging plate and the CCD camera. This low-<span class="hlt">flux</span> <span class="hlt">electron</span> diffraction (LFED) method made it possible to minimize the unfavorable effect of <span class="hlt">electron</span> beam damage and to give a reliable diffraction pattern from a small selected area (0.2μm(2)) on a corneocyte. Dependence of the 2-dimensional ED pattern on the size of the selected area showed that orientational correlation between lipid packing domains can persist over the area much larger than their domain size. The LFED method also allowed us to trace the detailed structural change induced by the <span class="hlt">electron</span> beam damage. The ED diffraction peak for the lattice constant of about 4.1nm decayed in three steps. The detailed analysis of these three steps suggested that a different type of orthorhombic structure exists interacted with the well-described hexagonal and orthorhombic structures, in the process of decay resulting from <span class="hlt">electron</span> beam damage. Copyright © 2013 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5275L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5275L"><span>Can the <span class="hlt">electron</span> heat <span class="hlt">flux</span> at 1 AU be collisional ? Results from kinetic simulations.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Landi, Simone; Pantellini, Filippo; Matteini, Lorenzo</p> <p>2014-05-01</p> <p>Recent results using statistically significant data of the solar wind at 1AU (see Bale et al. ApJL 769:L22, 2013) have shown that when the thermal Knudsen number, the ratio between the <span class="hlt">electron</span> mean free path and the temperature scale height, falls below ~0.3, the <span class="hlt">electron</span> heat <span class="hlt">flux</span> Q does rapidly approach the classical collisional Spitzer-Harm limit Q_SH ~ T5/2 dT/dr, where T is the temperature and r the heliocentric distance. This experimental finding seems to contradict a number of theoretical works which suggest that the collisional expression for the heat <span class="hlt">flux</span> is only guaranteed for Knudsen numbers smaller than ~0.001 (e.g. Shoub ApJ, 266, 339-369, 1983; Scudder & Karimabadi, ApJ, 770:26, 2013) . Indeed, using a fully kinetic model including the effect of Coulomb collisions and the expansion of the solar wind with heliocentric distance, we do observe that the heat <span class="hlt">flux</span> strength approaches the collisional value for Knudsen numbers below ~0.3, in rather good agreement with the experimental data of Bale et al (2013). However, closer inspection of the variation of the plasma parameters with heliocentric distance shows that for Knudsen numbers between 0.01-0.3 the heat <span class="hlt">flux</span> Q does NOT vary with temperature as predicted by Q_SH. We conclude that even though observations at 1 AU seem to indicate that the <span class="hlt">electron</span> heat <span class="hlt">flux</span> intensity Q approaches the collisional limit Q_SH for Knudsen below ~0.3, the latter is not a generally valid closure in the solar wind for Knudsen large that 0.01.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJB...90...56H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJB...90...56H"><span>Magnetic <span class="hlt">flux</span> and strain effects on <span class="hlt">electron</span> transport in a linear array of nanoscopic rings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hedin, Eric R.; Joe, Yong S.</p> <p>2017-03-01</p> <p><span class="hlt">Electron</span> transport through a linear array of nanoscopic rings with six quantum dot sites per ring is investigated in the presence of an external magnetic <span class="hlt">flux</span> producing an Aharonov-Bohm phase shift effect. A tight-binding model is employed to analytically calculate the transmission as a function of <span class="hlt">electron</span> energy, external <span class="hlt">flux</span>, and inter-site coupling parameters. Current vs. voltage relationships of the ring system are computed using a standard scattering theory of transport and shown to modulate between semiconductor and ohmic characteristics. System parameters are adjusted in order to study the effects of a longitudinal strain on the transmission properties of the linear multiple-ring array. Longitudinal strain is modeled with a Slater-Koster type theory and is demonstrated to affect the transmission properties primarily by narrowing the transmission bands and opening up additional bandgaps in the band structure. In addition, a universal resonant transmission condition as a function of <span class="hlt">flux</span> is extended to show that the application of strain causes the resonant transmission peaks to converge towards one-half of a <span class="hlt">flux</span> quantum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARA29008Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARA29008Z"><span>Coherent coupling of a superconducting <span class="hlt">flux</span> qubit to an <span class="hlt">electron</span> spin ensemble in diamond</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Xiaobo; Saito, Shiro; Kemp, Alexander; Kakuyanagi, Kosuke; Karimoto, Shin-Ichi; Nakano, Hayato; Munro, William J.; Tokura, Yasuhiro; Everitt, Mark S.; Nemoto, Kae; Kasu, Makoto; Mizuochi, Norikazu; Semba, Kouichi</p> <p>2012-02-01</p> <p>We have experimentally demonstrated coherent strong coupling between a single macroscopic superconducting artificial atom (a gap tunable <span class="hlt">flux</span> qubit [1]) and an ensemble of <span class="hlt">electron</span> spins in the form of nitrogen--vacancy color centres in diamond. We have observed coherent exchange of a single quantum of energy between a <span class="hlt">flux</span> qubit and a macroscopic ensemble consisting of about 3.0*10^7 NV- centers [2]. This is the first step towards the realization of a long-lived quantum memory and hybrid devices coupling microwave and optical systems. [1] Coherent operation of a gap-tunable <span class="hlt">flux</span> qubit X. B. Zhu, A. Kemp, S. Saito, K. Semba, APPLIED PHYSICS LETTERS, Volume: 97, Issue: 10 pp. 102503 (2010) [2] Coherent coupling of a superconducting <span class="hlt">flux</span> qubit to an <span class="hlt">electron</span> spin ensemble in diamond Xiaobo Zhu, Shiro Saito, Alexander Kemp, Kosuke Kakuyanagi, Shin-ichi Karimoto, Hayato Nakano, William J. Munro, Yasuhiro Tokura, Mark S. Everitt, Kae Nemoto, Makoto Kasu, Norikazu Mizuochi, and Kouichi Semba, Nature, Volume: 478, 221-224 (2011)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913490D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913490D"><span>Nearly relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> and ionospheric parameters as components of space weather</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dudnik, Oleksiy; Rothkaehl, Hanna; Matyjasiak, Barbara</p> <p>2017-04-01</p> <p>We present specific features detected in spatial distributions of magnetospheric high energy <span class="hlt">electrons</span> and in ionosphere plasma <span class="hlt">electron</span> densities and temperatures during a deep minimum of 11 year's cycle of solar activity. New outcome comes as a result of joint analysis of experimental data derived from the satellite telescope of <span class="hlt">electrons</span> and protons STEP-F aboard the low, circular and highly inclined orbit CORONAS-Photon satellite, and from Demeter satellite. The highly sensitive STEP-F instrument flown in 2009 and measured sub-relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> and protons of intermediate energies by extensive-angled telescopic system of detectors at the height of 550 km covering the wide range of McIlwain L-parameters from 1 up to 20. We present peculiar characteristics of <span class="hlt">electron</span> flows in well-known Van Allen outer and inner radiation belts, inside the region of South Atlantic Anomaly and outside of mentioned zones observed during the first half of May, 2009. In spite of extremely low solar activity, and the presence of single geomagnetic substorm on May, 6-8, which was characterized by remarkably small Dst =-30 nT, substantial variations of <span class="hlt">electron</span> <span class="hlt">fluxes</span> with energies E > 180 keV came into being in all zones of enhanced charge radiation. It was clearly seen elongation of the South Atlantic Anomaly in terms of <span class="hlt">electron</span> flows up to low and near-equatorial latitudes to eastern-directed longitudes. Throughout the whole period there were recorded two radiation belts in the inner magnetosphere: well-studied at L 2.3, and additional one at L 1.6. The third radiation belt at L 1.6 had specific belt-shaped profile of particle <span class="hlt">fluxes</span>, and registered at broad range of longitudes that do not coincide with those ones related to the Anomaly location. The analyses of subrelativistic <span class="hlt">electrons</span> at the heights of upper ionosphere and inospheric plasma parameters has been analysed. From this standpoint we consider <span class="hlt">electron</span> <span class="hlt">flux</span> pulsations during various phases of geomagnetic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1320..227V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1320..227V"><span>Stormtime Dynamics of the Relativistic <span class="hlt">Electron</span> <span class="hlt">Flux</span> in Earth's Radiation Belts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vassiliadis, D.</p> <p>2011-01-01</p> <p>A state-vector representation is a powerful technique for describing complex plasma systems. Its framework can be adapted for classification methods which can be used to analyze the system's history and for prediction methods which can serve to forecast its future activity. A state-vector description is developed for the <span class="hlt">electron</span> <span class="hlt">flux</span> dynamics in Earth's radiation belts, based on an 11-year (1993-2003) dataset of high-cadence <span class="hlt">flux</span> measurements from a low-Earth (SAMPEX) orbit over a wide L range and at a fixed energy (2-6 MeV). A clustering algorithm is used to divide the state space into regions, or clusters of vectors, and it becomes evident that <span class="hlt">flux</span> intensifications during storms correspond to characteristic transitions in state space following geoeffective interplanetary disturbances (such as interplanetary coronal mass ejections and high-speed streams). Examples are discussed to show that the classification is valid for medium-term (several-days) and long-term (solar-cycle-phase) timescales. The state-vector representation is then used as the basis of a predictive model of the <span class="hlt">flux</span> distribution given upstream solar wind measurements. It is found that model accuracy of storm prediction is maximized if the model is tuned at a highly nonlinear regime. The relation to earlier state representations and models of the radiation belt <span class="hlt">flux</span> is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.9560G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.9560G"><span>The role of localized inductive electric fields in <span class="hlt">electron</span> injections around dipolarizing <span class="hlt">flux</span> bundles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabrielse, Christine; Harris, Camilla; Angelopoulos, Vassilis; Artemyev, Anton; Runov, Andrei</p> <p>2016-10-01</p> <p>We study energetic <span class="hlt">electron</span> injections by using an analytical model that self-consistently describes electric and magnetic field perturbations of a transient, localized dipolarizing <span class="hlt">flux</span> bundle (DFB). This simple model reproduces most injection signatures at multiple locations simultaneously, reaffirming earlier findings that an earthward-traveling DFB can both transport and accelerate <span class="hlt">electrons</span> to suprathermal energies, and can thus be considered an important driver of short-lived ( < 10 min) injections. We find that energetic <span class="hlt">electron</span> drift paths are greatly influenced by the sharp magnetic field gradients around a localized DFB. Because a DFB is so localized (only a few RE wide across the tail), there are strong duskward magnetic field gradients on the DFB's dawn flank and strong dawnward magnetic field gradients on its dusk flank. <span class="hlt">Electrons</span> on the DFB's dawnside therefore ∇B drift farther earthward from the reconnection site, whereas <span class="hlt">electrons</span> on its duskside can potentially evacuate the inner magnetosphere by ∇B drifting tailward. This results in <span class="hlt">flux</span> decrease at the front's duskside. As a result, the source of <span class="hlt">electrons</span> observed during injection depends sensitively on the spacecraft location relative to the DFB and on the DFB's properties. We similarly find that the process of <span class="hlt">electron</span> energization depends on how the <span class="hlt">electrons</span> interact with the DFB. The initial injection signature is from <span class="hlt">electrons</span> that interact with the front and gain the majority of their energy from the increasing magnetic field (∂B/∂t), whereas populations that arrive later gain most of their energy from ∇B drifting across the flow channel and against the DFB's electric fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22408105','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22408105"><span>Fast <span class="hlt">electron</span> <span class="hlt">flux</span> driven by lower hybrid wave in the scrape-off layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Li, Y. L.; Xu, G. S.; Wang, H. Q.; Wan, B. N.; Chen, R.; Wang, L.; Gan, K. F.; Yang, J. H.; Zhang, X. J.; Liu, S. C.; Li, M. H.; Ding, S.; Yan, N.; Zhang, W.; Hu, G. H.; Liu, Y. L.; Shao, L. M.; Li, J.; Chen, L.; Zhao, N.; and others</p> <p>2015-02-15</p> <p>The fast <span class="hlt">electron</span> <span class="hlt">flux</span> driven by Lower Hybrid Wave (LHW) in the scrape-off layer (SOL) in EAST is analyzed both theoretically and experimentally. The five bright belts flowing along the magnetic field lines in the SOL and hot spots at LHW guard limiters observed by charge coupled device and infrared cameras are attributed to the fast <span class="hlt">electron</span> <span class="hlt">flux</span>, which is directly measured by retarding field analyzers (RFA). The current carried by the fast <span class="hlt">electron</span> <span class="hlt">flux</span>, ranging from 400 to 6000 A/m{sup 2} and in the direction opposite to the plasma current, is scanned along the radial direction from the limiter surface to the position about 25 mm beyond the limiter. The measured fast <span class="hlt">electron</span> <span class="hlt">flux</span> is attributed to the high parallel wave refractive index n{sub ||} components of LHW. According to the antenna structure and the LHW power absorbed by plasma, a broad parallel electric field spectrum of incident wave from the antennas is estimated. The radial distribution of LHW-driven current density is analyzed in SOL based on Landau damping of the LHW. The analytical results support the RFA measurements, showing a certain level of consistency. In addition, the deposition profile of the LHW power density in SOL is also calculated utilizing this simple model. This study provides some fundamental insight into the heating and current drive effects induced by LHW in SOL, and should also help to interpret the observations and related numerical analyses of the behaviors of bright belts and hot spots induced by LHW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhyA..484..465K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhyA..484..465K"><span>Modeling of possible localized <span class="hlt">electron</span> <span class="hlt">flux</span> in cosmic rays with Alpha Magnetic Spectrometer measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwang-Hua, Chu Rainer</p> <p>2017-10-01</p> <p>Discrete quantum Boltzmann model together with the introduction of an external-field-tuned orientation parameter as well as the acoustic analog are adopted to study the possible localization of <span class="hlt">electron</span> (fermion) <span class="hlt">flux</span> in cosmic rays considering the precision measurement with the Alpha Magnetic Spectrometer (AMS) on the International Space Station (ISS). Our approximate results match qualitatively with those data measured with the AMS on the ISS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1212474-background-correction-algorithm-van-allen-probes-mageis-electron-flux-measurements','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1212474-background-correction-algorithm-van-allen-probes-mageis-electron-flux-measurements"><span>A background correction algorithm for Van Allen Probes MagEIS <span class="hlt">electron</span> <span class="hlt">flux</span> measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Claudepierre, S. G.; O'Brien, T. P.; Blake, J. B.; ...</p> <p>2015-07-14</p> <p>We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic <span class="hlt">Electron</span> Ion Spectrometer (MagEIS) <span class="hlt">electron</span> <span class="hlt">flux</span> measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS <span class="hlt">electron</span> data: inner zone protons and bremsstrahlung X-rays generated by energetic <span class="hlt">electrons</span> interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS <span class="hlt">electron</span> channels (~30–500 keV) and in regions of geospace where multi-M eV <span class="hlt">electrons</span> are present. Inner zone protons produce contamination in all MagEIS energymore » channels at roughly L < 2.5. The background-corrected MagEIS <span class="hlt">electron</span> data produce a more accurate measurement of the <span class="hlt">electron</span> radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth <span class="hlt">electron</span> environment and informing the next generation of spacecraft design models (e.g., AE9).« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1212474','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1212474"><span>A background correction algorithm for Van Allen Probes MagEIS <span class="hlt">electron</span> <span class="hlt">flux</span> measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Claudepierre, S. G.; O'Brien, T. P.; Blake, J. B.; Fennell, J. F.; Roeder, J. L.; Clemmons, J. H.; Looper, M. D.; Mazur, J. E.; Mulligan, T. M.; Spence, H. E.; Reeves, G. D.; Friedel, R. H. W.; Henderson, M. G.; Larsen, B. A.</p> <p>2015-07-14</p> <p>We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes Magnetic <span class="hlt">Electron</span> Ion Spectrometer (MagEIS) <span class="hlt">electron</span> <span class="hlt">flux</span> measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS <span class="hlt">electron</span> data: inner zone protons and bremsstrahlung X-rays generated by energetic <span class="hlt">electrons</span> interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS <span class="hlt">electron</span> channels (~30–500 keV) and in regions of geospace where multi-M eV <span class="hlt">electrons</span> are present. Inner zone protons produce contamination in all MagEIS energy channels at roughly L < 2.5. The background-corrected MagEIS <span class="hlt">electron</span> data produce a more accurate measurement of the <span class="hlt">electron</span> radiation belts, as most earlier measurements suffer from unquantifiable and uncorrectable contamination in this harsh region of the near-Earth space environment. These background-corrected data will also be useful for spacecraft engineering purposes, providing ground truth for the near-Earth <span class="hlt">electron</span> environment and informing the next generation of spacecraft design models (e.g., AE9).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ASSP...32..165J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ASSP...32..165J"><span>Degradation of Silicone Oils Exposed to Geostationary Environment Components: Ultraviolet Radiations and <span class="hlt">Electron</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jochem, H.; Rejsek-Riba, V.; Maerten, E.; Baceiredo, A.; Remaury, S.</p> <p></p> <p>Degradation of polydimethylsiloxane and vinyl-terminated polydimethylsiloxane oils exposed to UV radiation or 1.25 MeV <span class="hlt">electron</span> <span class="hlt">flux</span> was investigated using EPR, GC Headspace, NMR, GPC and UV-vis-NIR spectroscopy. To examine the influence of synthetic method, these two oils were prepared by ring opening polymerization using either an inorganic initiator KOH or an organic catalyst N-Heterocyclic carbene. Under UV radiation, any chemical change is observed for polydimethylsiloxane, whereas vinyl-terminated polydimethylsiloxane presents a decrease of vinyl functions and an increase of chain length. Both polydimethylsiloxane and vinyl terminated polydimethylsiloxane demonstrated a degradation of thermo-optical properties, more significant for oils synthesized with organic catalyst. By improving oil purification, the degradation of thermo-optical properties can be reduced. Effects of <span class="hlt">electron</span> <span class="hlt">flux</span> are similar for each oil, thus independently of synthetic method and end functions. <span class="hlt">Electron</span> <span class="hlt">flux</span> generates important chemical damages initiated by homolytic chain scissions. Radical recombination produces gases (methane and ethane), new functions (Si-H) and bonds across silicone chains leading to a solid state material. Crosslinking of chains occurs by formation of R-Si-(O)3 and Si-CH2-Si groups. Silyl radicals are trapped in the polymer network and can be detected even 1 week after the end of irradiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM41A2465O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM41A2465O"><span>Statistical Observations and Predictions of Time Changes in <span class="hlt">Electron</span> <span class="hlt">Flux</span> at Geosynchronous Orbit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olson, D. K.; Larsen, B.; Friedel, R. H.; Geoffrey, R.</p> <p>2015-12-01</p> <p>A statistical survey of time changes in particle <span class="hlt">flux</span> values (df/dt) at geosynchronous orbit reveals trends that are instructive to predictive magnetosphere models. A single spacecraft can provide short time scale df/dt measurements, while multiple spacecraft can provide values over periods comparable to the spacecraft separation. Using data from multiple LANL-GEO spacecraft provides a unique view of temporal and spatial variations that allow us to gauge time and length scales for changing particle <span class="hlt">fluxes</span> at GEO. These scales provide a base ability to predict the plasma environment conditions for spacecraft crossing GEO. Probability distribution functions based on <span class="hlt">electron</span> df/dt values are used to predict the <span class="hlt">electron</span> <span class="hlt">flux</span> at a given magnetic local time at GEO based on prior measurements. The predictions, when compared to new data taken in the same region, provide some measure of how the <span class="hlt">electron</span> plasma environment at GEO has changed in the interim period. These predictions are compared to data from the Van Allen Probes as their orbits cross GEO to verify the validity of this technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880042165&hterms=ISEE-3&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DISEE-3','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880042165&hterms=ISEE-3&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DISEE-3"><span>Interplanetary magnetic field orientations associated with bidirectional <span class="hlt">electron</span> heat <span class="hlt">fluxes</span> detected at ISEE 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stansberry, J. A.; Gosling, J. T.; Thomsen, M. F.; Bame, S. J.; Smith, E. J.</p> <p>1988-01-01</p> <p>A statistical survey of interplanetary magnetic field orientations associated with bidirectional <span class="hlt">electron</span> heat <span class="hlt">fluxes</span> observed at ISEE 3 in orbit about the Sunward Lagrange point indicates that magnetic connection of the spacecraft to the earth's shock was frequently the source of the bidirectionality. When the interplanetary magnetic field was oriented within 5 deg of the earth-spacecraft line, backstreaming <span class="hlt">electrons</span> from the bow shock were clearly observed approximately 18 percent of the time, and connections apparently occurred for angles as large as about 30-35 deg.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...712633A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...712633A"><span><span class="hlt">Electron-flux</span> infrared response to varying π-bond topology in charged aromatic monomers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Álvaro Galué, Héctor; Oomens, Jos; Buma, Wybren Jan; Redlich, Britta</p> <p>2016-08-01</p> <p>The interaction of delocalized π-<span class="hlt">electrons</span> with molecular vibrations is key to charge transport processes in π-conjugated organic materials based on aromatic monomers. Yet the role that specific aromatic motifs play on charge transfer is poorly understood. Here we show that the molecular edge topology in charged catacondensed aromatic hydrocarbons influences the Herzberg-Teller coupling of π-<span class="hlt">electrons</span> with molecular vibrations. To this end, we probe the radical cations of picene and pentacene with benchmark armchair- and zigzag-edges using infrared multiple-photon dissociation action spectroscopy and interpret the recorded spectra via quantum-chemical calculations. We demonstrate that infrared bands preserve information on the dipolar π-<span class="hlt">electron-flux</span> mode enhancement, which is governed by the dynamical evolution of vibronically mixed and correlated one-<span class="hlt">electron</span> configuration states. Our results reveal that in picene a stronger charge π-<span class="hlt">flux</span> is generated than in pentacene, which could justify the differences of <span class="hlt">electronic</span> properties of armchair- versus zigzag-type families of technologically relevant organic molecules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...848L...3F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...848L...3F"><span>Origin of the Differential <span class="hlt">Fluxes</span> of Low-energy <span class="hlt">Electrons</span> in the Inner Heliosheath</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fahr, H. J.; Krimigis, S. M.; Fichtner, H.; Scherer, K.; Sylla, A.; Ferreira, S. E. S.; Potgieter, M. S.</p> <p>2017-10-01</p> <p>The study addresses the question of the origin of low-energy <span class="hlt">electrons</span> measured by Voyager 1 in the multi-keV range in the inner heliosheath. It intends to demonstrate that the observed keV-<span class="hlt">fluxes</span> of <span class="hlt">electrons</span> are consistent with their transmission through the termination shock under the influence of the associated electrostatic field. A power-law representation of the <span class="hlt">electron</span> velocity distribution just downstream of the solar wind termination shock is motivated and formulated in terms of a so-called κ-distribution function. From this initial function spectral <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the range 40–70 keV are derived and compared to the data. It is shown that with κ-values between 7 and 8 the data can be satisfactorily explained. Given these comparatively high κ-values, it is concluded that the <span class="hlt">electron</span> distribution just downstream of the termination shock relaxes toward but does not reach a Maxwellian shape in the inner heliosheath.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5013661','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5013661"><span><span class="hlt">Electron-flux</span> infrared response to varying π-bond topology in charged aromatic monomers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Álvaro Galué, Héctor; Oomens, Jos; Buma, Wybren Jan; Redlich, Britta</p> <p>2016-01-01</p> <p>The interaction of delocalized π-<span class="hlt">electrons</span> with molecular vibrations is key to charge transport processes in π-conjugated organic materials based on aromatic monomers. Yet the role that specific aromatic motifs play on charge transfer is poorly understood. Here we show that the molecular edge topology in charged catacondensed aromatic hydrocarbons influences the Herzberg-Teller coupling of π-<span class="hlt">electrons</span> with molecular vibrations. To this end, we probe the radical cations of picene and pentacene with benchmark armchair- and zigzag-edges using infrared multiple-photon dissociation action spectroscopy and interpret the recorded spectra via quantum-chemical calculations. We demonstrate that infrared bands preserve information on the dipolar π-<span class="hlt">electron-flux</span> mode enhancement, which is governed by the dynamical evolution of vibronically mixed and correlated one-<span class="hlt">electron</span> configuration states. Our results reveal that in picene a stronger charge π-<span class="hlt">flux</span> is generated than in pentacene, which could justify the differences of <span class="hlt">electronic</span> properties of armchair- versus zigzag-type families of technologically relevant organic molecules. PMID:27577323</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818101T"><span>Variation of energetic <span class="hlt">electron</span> <span class="hlt">flux</span> in Earth's radiation belts based on Van Allen Probes observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, Rongxin; Zhong, Zhihong; Yu, Deyin</p> <p>2016-04-01</p> <p>The Earth's radiation belts have been an important research topic of solar-terrestrial physics from 1958. In 2012, Van Allen Probes (VAP) were launched into near-equatorial orbit and provide very good in-situ observations of energetic particles in inner magnetosphere. Since magnetospheric substorm can cause the severe disturbance of the Earth's megnetospheric environment, here we focus on the characteristics of energetic <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the radiation belts during substorm time and non-storm time. Energetic <span class="hlt">electron</span> data observed by the Magnetic <span class="hlt">Electron</span> Ion Spectrometer (MagEIS) and Energetic Particle Composition and Thermal Plasma Suite (ECT) of VAP during 2012 to 2014 are carefully analyzed. We select portions of energetic <span class="hlt">electron</span> data from substorm onset phase, growth phase, recovery phase, and quiet time, and make a comparisons with theoretical computations. We find that the <span class="hlt">electron</span> differential <span class="hlt">fluxes</span> present E-1 shape at lower energies (<1MeV), and have a sharp transition with steeper slopes at high energies for large L-shells, which are in coincidence with Mauk's model [Mauk et al., 2010].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820028335&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Denergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820028335&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Denergy"><span>A satellite investigation of energy <span class="hlt">flux</span> and inferred potential drop in auroral <span class="hlt">electron</span> energy spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Menietti, J. D.; Burch, J. L.</p> <p>1981-01-01</p> <p>The relationship between auroral <span class="hlt">electron</span> energy <span class="hlt">flux</span> and the inferred accelerating potential drop for accelerated Maxwellian distributions is investigated on the basis of Atmospheric Explorer D spectral measurements. An analytical approximation for the total downward energy <span class="hlt">flux</span> carried by an isotropic Maxwellian <span class="hlt">electron</span> population accelerated by a field-aligned electrostatic potential drop is derived which is valid for values of the <span class="hlt">electron</span> energy/characteristic accelerated Maxwellian distribution energy which are less than the difference between the ratio of the magnetic field strengths at the altitude of observation and the altitude of potential drop, and unity. Data from the Low Energy <span class="hlt">Electron</span> Experiment on board AE D obtained on both the dayside and the nightside during periods of significant inverted-V type <span class="hlt">electron</span> precipitation shows that the 455 energy spectra considered, 160 of them, obtained between 60 and 85 deg invariant latitude, could be fit to accelerated Maxwellian distributions. The 160 Maxwellian spectra are then shown to be in agreement with the predictions of the accelerated Maxwellian model. Finally, analysis of individual spectra suggests that the altitude of the inferred potential drop is at a maximum near the center of the inverted-V structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87k4101N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87k4101N"><span>Liquid-phase catalytic reactor combined with measurement of hot <span class="hlt">electron</span> <span class="hlt">flux</span> and chemiluminescence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nedrygailov, Ievgen I.; Lee, Changhwan; Moon, Song Yi; Lee, Hyosun; Park, Jeong Young</p> <p>2016-11-01</p> <p>Understanding the role of <span class="hlt">electronically</span> nonadiabatic interactions during chemical reactions on metal surfaces in liquid media is of great importance for a variety of applications including catalysis, electrochemistry, and environmental science. Here, we report the design of an experimental apparatus for detection of the highly excited (hot) <span class="hlt">electrons</span> created as a result of nonadiabatic energy transfer during the catalytic decomposition of hydrogen peroxide on thin-film metal-semiconductor nanodiodes. The apparatus enables the measurement of hot <span class="hlt">electron</span> flows and related phenomena (e.g., surface chemiluminescence) as well as the corresponding reaction rates at different temperatures. The products of the chemical reaction can be characterized in the gaseous phase by means of gas chromatography. The combined measurement of hot <span class="hlt">electron</span> <span class="hlt">flux</span>, catalytic activity, and light emission can lead to a fundamental understanding of the elementary processes occurring during the heterogeneous catalytic reaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddropout"><span>Interplanetary magnetic field connection to the sun during <span class="hlt">electron</span> heat <span class="hlt">flux</span> dropouts in the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, R. P.; Kahler, S. W.</p> <p>1992-01-01</p> <p>The paper discusses observations of 2- to 8.5-keV <span class="hlt">electrons</span>, made by measurements aboard the ISEE 3 spacecraft during the periods of heat <span class="hlt">flux</span> decreases (HFDs) reported by McComas et al. (1989). In at least eight of the total of 25 HFDs observed, strong streaming of <span class="hlt">electrons</span> that were equal to or greater than 2 keV outward from the sun was recorded. In one HFD, an impulsive solar <span class="hlt">electron</span> event was observed with an associated type III radio burst, which could be tracked from the sun to about 1 AU. It is concluded that, in many HFDs, the interplanetary field is still connected to the sun and that some energy-dependent process may produce HFDs without significantly perturbing <span class="hlt">electrons</span> of higher energies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27910578','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27910578"><span>Liquid-phase catalytic reactor combined with measurement of hot <span class="hlt">electron</span> <span class="hlt">flux</span> and chemiluminescence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nedrygailov, Ievgen I; Lee, Changhwan; Moon, Song Yi; Lee, Hyosun; Park, Jeong Young</p> <p>2016-11-01</p> <p>Understanding the role of <span class="hlt">electronically</span> nonadiabatic interactions during chemical reactions on metal surfaces in liquid media is of great importance for a variety of applications including catalysis, electrochemistry, and environmental science. Here, we report the design of an experimental apparatus for detection of the highly excited (hot) <span class="hlt">electrons</span> created as a result of nonadiabatic energy transfer during the catalytic decomposition of hydrogen peroxide on thin-film metal-semiconductor nanodiodes. The apparatus enables the measurement of hot <span class="hlt">electron</span> flows and related phenomena (e.g., surface chemiluminescence) as well as the corresponding reaction rates at different temperatures. The products of the chemical reaction can be characterized in the gaseous phase by means of gas chromatography. The combined measurement of hot <span class="hlt">electron</span> <span class="hlt">flux</span>, catalytic activity, and light emission can lead to a fundamental understanding of the elementary processes occurring during the heterogeneous catalytic reaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=college+dropouts&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcollege%2Bdropouts','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=college+dropouts&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcollege%2Bdropouts"><span>Interplanetary magnetic field connection to the sun during <span class="hlt">electron</span> heat <span class="hlt">flux</span> dropouts in the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, R. P.; Kahler, S. W.</p> <p>1992-01-01</p> <p>The paper discusses observations of 2- to 8.5-keV <span class="hlt">electrons</span>, made by measurements aboard the ISEE 3 spacecraft during the periods of heat <span class="hlt">flux</span> decreases (HFDs) reported by McComas et al. (1989). In at least eight of the total of 25 HFDs observed, strong streaming of <span class="hlt">electrons</span> that were equal to or greater than 2 keV outward from the sun was recorded. In one HFD, an impulsive solar <span class="hlt">electron</span> event was observed with an associated type III radio burst, which could be tracked from the sun to about 1 AU. It is concluded that, in many HFDs, the interplanetary field is still connected to the sun and that some energy-dependent process may produce HFDs without significantly perturbing <span class="hlt">electrons</span> of higher energies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21476101','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21476101"><span>High energy <span class="hlt">electron</span> <span class="hlt">fluxes</span> in dc-augmented capacitively coupled plasmas I. Fundamental characteristics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang Mingmei; Kushner, Mark J.</p> <p>2010-01-15</p> <p>Power deposition from <span class="hlt">electrons</span> in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary <span class="hlt">electrons</span> through sheaths produced by ion, <span class="hlt">electron</span>, or photon bombardment of electrodes. The sheath accelerated <span class="hlt">electrons</span> can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy <span class="hlt">electrons</span> interact with the wafer. To control the energy and increase the <span class="hlt">flux</span> of the high energy <span class="hlt">electrons</span>, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy <span class="hlt">electrons</span> having a narrow angular spread (<1 deg. ) can be produced incident on the wafer. The maximum energy in the high energy <span class="hlt">electron</span> <span class="hlt">flux</span> scales as {epsilon}{sub max}=-V{sub dc}+V{sub rf}+V{sub rf0}, for a voltage on the dc electrode of V{sub dc}, rf voltage of V{sub rf}, and dc bias on the rf electrode of V{sub rf0}. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9428E..0OR','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9428E..0OR"><span><span class="hlt">Electron</span> energy distribution control by fiat: breaking from the conventional <span class="hlt">flux</span> ratio scaling rules in etch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ranjan, Alok; Wang, Mingmei; Sherpa, Sonam; Ventzek, Peter</p> <p>2015-03-01</p> <p>With shrinking critical dimensions, minimizing each of aspect ratio dependent etching (ARDE), bowing, undercut, selectivity, and within die uniformly across a wafer is met by trading off one requirement against another. The problem of trade-offs is especially critical. At the root of the problem is that roles radical <span class="hlt">flux</span>, ion <span class="hlt">flux</span> and ion energy play may be both good and bad. Increasing one parameter helps meeting one requirement but hinders meeting the other. Managing process by managing <span class="hlt">flux</span> ratios and ion energy alone with conventional sources is not adequate because surface chemistry is uncontrollable. At the root of lack of control is that the <span class="hlt">electron</span> energy distribution function (eedf) has not been controlled. Fortunately the high density surface wave sources control the eedf by fiat. High density surface wave sources are characterized by distinct plasma regions: an active plasma generation region with high <span class="hlt">electron</span> temperature (Te) and an ionization free but chemistry rich diffusive region (low Te region). Pressure aids is segregating the regions by proving a means for momentum relaxation between the source and downstream region. "Spatial pulsing" allows access to plasma chemistry with reasonably high ion <span class="hlt">flux</span>, from the active plasma generation region, just above the wafer. Low plasma potential enables precise passivation of surfaces which is critical for atomic layer etch (ALE) or high precision etch where the roles of plasma species can be limited to their purposed roles. High precision etch need not be at the cost of speed and manufacturability. Large ion <span class="hlt">flux</span> at precisely controlled ion energy with RLSATM realizes fast desorption steps for ALE without compromising process throughput and precision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM22A..08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM22A..08G"><span>The Role of Localized Inductive Electric Fields in <span class="hlt">Electron</span> Injections Around Dipolarizing <span class="hlt">Flux</span> Bundles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabrielse, C.; Harris, C.; Angelopoulos, V.; Runov, A.</p> <p>2015-12-01</p> <p>We study energetic <span class="hlt">electron</span> injections using an analytical model that describes self-consistent electric and magnetic field perturbations of a transient, localized dipolarizing <span class="hlt">flux</span> bundle (DFB). This simple model can reproduce most injection signatures at multiple locations simultaneously, reaffirming earlier findings that an earthward-traveling DFB can both transport and accelerate <span class="hlt">electrons</span> to suprathermal energies, and can thus be considered as the primary driver of short-lived (~<10 min) injections. We find that energetic <span class="hlt">electron</span> drift paths are greatly influenced by the sharp magnetic field gradients around the localized DFB. If the gradients are weak the energetic <span class="hlt">electrons</span> initiating at reconnection will drift out of the flow channel such that the observed injection is comprised mostly of plasma sheet <span class="hlt">electrons</span>. However, if the duskward magnetic field gradients on the DFB's dawn flank are strong they can cause <span class="hlt">electrons</span> to drift further earthward from the reconnection site than due to E x B alone. Similarly, strong dawnward magnetic field gradients on the DFB's dusk flank can extract energetic <span class="hlt">electrons</span> from the inner magnetosphere out to the plasma sheet, where they can either be recirculated earthward or remain at higher L-shells. Therefore, the source of <span class="hlt">electrons</span> observed during injection depends sensitively on the spacecraft location relative to the DFB and on the DFB's properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1183079','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1183079"><span>Thermal <span class="hlt">flux</span> limited <span class="hlt">electron</span> Kapitza conductance in copper-niobium multilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cheaito, Ramez; Hattar, Khalid Mikhiel; Gaskins, John T.; Yadav, Ajay K.; Duda, John C.; Beechem, III, Thomas Edwin; Ihlefeld, Jon; Piekos, Edward S.; Baldwin, Jon K.; Misra, Amit; Hopkins, Patrick E.</p> <p>2015-03-05</p> <p>The interplay between the contributions of <span class="hlt">electron</span> thermal <span class="hlt">flux</span> and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers was studied. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the <span class="hlt">electron</span> diffuse mismatch model. The results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the <span class="hlt">electron</span> energy <span class="hlt">flux</span> in the metallic layers, rather than <span class="hlt">electron</span> mean free path or scattering processes at the interface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1183079-thermal-flux-limited-electron-kapitza-conductance-copper-niobium-multilayers','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1183079-thermal-flux-limited-electron-kapitza-conductance-copper-niobium-multilayers"><span>Thermal <span class="hlt">flux</span> limited <span class="hlt">electron</span> Kapitza conductance in copper-niobium multilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Cheaito, Ramez; Hattar, Khalid Mikhiel; Gaskins, John T.; ...</p> <p>2015-03-05</p> <p>The interplay between the contributions of <span class="hlt">electron</span> thermal <span class="hlt">flux</span> and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers was studied. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the <span class="hlt">electron</span> diffusemore » mismatch model. The results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the <span class="hlt">electron</span> energy <span class="hlt">flux</span> in the metallic layers, rather than <span class="hlt">electron</span> mean free path or scattering processes at the interface.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JPhCS.409a2223A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JPhCS.409a2223A"><span>New low threshold detectors for measuring <span class="hlt">electron</span> and gamma ray <span class="hlt">fluxes</span> from thunderclouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arakelyan, Karen; Avakyan, Karen; Chilingarian, Ashot; Daryan, Ara; Melkumyan, Laura; Pokhsraryan, David; Sargsyan, David</p> <p>2013-02-01</p> <p>Strong electric fields inside thunderclouds give rise to enhanced <span class="hlt">fluxes</span> of high-energy <span class="hlt">electrons</span> and, consequently, gamma rays and neutrons. During thunderstorms at mountain Aragats, hundreds of Thunderstorm Ground Enhancements (TGEs) comprising millions of energetic <span class="hlt">electrons</span> and gamma rays, as well as neutrons, were detected at Aragats Space Environmental Center (ASEC) on 3200 m altitude. The energy spectra of the <span class="hlt">electrons</span> have an exponential shape and extend in energy range 2- 30 MeV. Recovered energy spectra of the gamma rays is also exponential in energy range 2-10 MeV, then turns to power law and is extending up to 100 MeV. It is of upmost importance to research energy spectra of TGE <span class="hlt">electrons</span> and gamma rays from the lowest possible energies to clarify the shape of energy spectra and huge multiplication of the avalanche particles. The particle detectors operated at ASEC was designed for the registration of solar modulation effects and the lowering energy threshold was not of first importance. Thus, particle detectors have energy threshold of 7-10 MeV. The new generation of ASEC detectors comprises from 1 and 3 cm thick molded plastic scintillators arranged in stacks (3cm and 1cm STAND detectors) and in cubical structures surrounded thick scintillators and NaI crystals for purification of detected neutral <span class="hlt">flux</span> (Cube 1 cm and Cube 3 cm detectors). In presented paper we describe new detectors and analyze their operational characteristics, as well as provide examples of TGE detection with new techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22412772','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22412772"><span>Thermal <span class="hlt">flux</span> limited <span class="hlt">electron</span> Kapitza conductance in copper-niobium multilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cheaito, Ramez; Gaskins, John T.; Duda, John C.; Hopkins, Patrick E.; Hattar, Khalid; Beechem, Thomas E.; Ihlefeld, Jon F.; Piekos, Edward S.; Yadav, Ajay K.; Baldwin, Jon K.; Misra, Amit</p> <p>2015-03-02</p> <p>We study the interplay between the contributions of <span class="hlt">electron</span> thermal <span class="hlt">flux</span> and interface scattering to the Kapitza conductance across metal-metal interfaces through measurements of thermal conductivity of copper-niobium multilayers. Thermal conductivities of copper-niobium multilayer films of period thicknesses ranging from 5.4 to 96.2 nm and sample thicknesses ranging from 962 to 2677 nm are measured by time-domain thermoreflectance over a range of temperatures from 78 to 500 K. The Kapitza conductances between the Cu and Nb interfaces in multilayer films are determined from the thermal conductivities using a series resistor model and are in good agreement with the <span class="hlt">electron</span> diffuse mismatch model. Our results for the thermal boundary conductance between Cu and Nb are compared to literature values for the thermal boundary conductance across Al-Cu and Pd-Ir interfaces, and demonstrate that the interface conductance in metallic systems is dictated by the temperature derivative of the <span class="hlt">electron</span> energy <span class="hlt">flux</span> in the metallic layers, rather than <span class="hlt">electron</span> mean free path or scattering processes at the interface.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...833...87C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...833...87C"><span>Radio Diagnostics of <span class="hlt">Electron</span> Acceleration Sites During the Eruption of a <span class="hlt">Flux</span> Rope in the Solar Corona</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carley, Eoin P.; Vilmer, Nicole; Gallagher, Peter T.</p> <p>2016-12-01</p> <p><span class="hlt">Electron</span> acceleration in the solar corona is often associated with flares and the eruption of twisted magnetic structures known as <span class="hlt">flux</span> ropes. However, the locations and mechanisms of such particle acceleration during the flare and eruption are still subject to much investigation. Observing the exact sites of particle acceleration can help confirm how the flare and eruption are initiated and how they evolve. Here we use the Atmospheric Imaging Assembly to analyze a flare and erupting <span class="hlt">flux</span> rope on 2014 April 18, while observations from the Nançay Radio Astronomy Facility allow us to diagnose the sites of <span class="hlt">electron</span> acceleration during the eruption. Our analysis shows evidence of a pre-formed <span class="hlt">flux</span> rope that slowly rises and becomes destabilized at the time of a C-class flare, plasma jet, and the escape of ≳75 keV <span class="hlt">electrons</span> from the rope center into the corona. As the eruption proceeds, continued acceleration of <span class="hlt">electrons</span> with energies of ˜5 keV occurs above the <span class="hlt">flux</span> rope for a period over 5 minutes. At the flare peak, one site of <span class="hlt">electron</span> acceleration is located close to the flare site, while another is driven by the erupting <span class="hlt">flux</span> rope into the corona at speeds of up to 400 km s-1. Energetic <span class="hlt">electrons</span> then fill the erupting volume, eventually allowing the <span class="hlt">flux</span> rope legs to be clearly imaged from radio sources at 150-445 MHz. Following the analysis of Joshi et al. (2015), we conclude that the sites of energetic <span class="hlt">electrons</span> are consistent with <span class="hlt">flux</span> rope eruption via a tether cutting or <span class="hlt">flux</span> cancellation scenario inside a magnetic fan-spine structure. In total, our radio observations allow us to better understand the evolution of a <span class="hlt">flux</span> rope eruption and its associated <span class="hlt">electron</span> acceleration sites, from eruption initiation to propagation into the corona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSM31C..07B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSM31C..07B"><span>Ion Outflow in the Dayside Cusp Ionosphere and its Dependence on Soft <span class="hlt">Electron</span> Energy <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burchill, J. K.; Knudsen, D. J.; Clemmons, J. H.; Oksavik, K.; Pfaff, R. F.; Steigies, C. T.; Yau, A. W.; Yeoman, T. K.</p> <p>2009-12-01</p> <p>We investigate the origin of low energy (Ek<10 eV) ion upflows in Earth's low-altitude dayside cusp region. The Cusp-2002 sounding rocket flew from Ny Ålesund, Svalbard, on 14 December 2002, carrying plasma and field instrumentation to an altitude of 768 km. The Suprathermal Ion Imager, a two-dimensional energy/arrival-angle spectrograph, observed large (>500 m/s) O+ upflows within the cusp at altitudes between 640 km and 768 km. We report a significant association between ion upflow and precipitating magnetosheath <span class="hlt">electron</span> energy <span class="hlt">flux</span> in this altitude range, but no causal links between upflow and either wave power or the magnitude of the dc electric field. The correspondence between upflow and logarithm of the <span class="hlt">electron</span> energy <span class="hlt">flux</span> suggests a mechanism whereby ions are accelerated locally by ambipolar electric fields that are driven by the soft <span class="hlt">electrons</span>. Significant ion upflows are not observed for <span class="hlt">electron</span> energy <span class="hlt">fluxes</span> below ˜1010 eV cm-2s-1, which suggests that any ambipolar fields present above 640 km must be in equilibrium with gravity and pressure gradients under this condition. The lack of correspondence between │E│ and upflow on the one hand, and wave power and upflow on the other, does not rule out these processes, but implies that, if operating, they are not local to the measurement region. We observe narrow regions of large downflow that imply either a re-balancing of the ionosphere toward a low-Te equilibrium during which gravity dominates the pressure gradients, or convection of the upflowing ions away from the precipitation region, outside of which the ions must fall back into equilibrium at lower altitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMAE31A3396A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMAE31A3396A"><span>In-Situ observation of energetic <span class="hlt">electron</span> <span class="hlt">fluxes</span> inside thunderclouds using Balloon-borne instruments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arabshahi, S.; Vodopiyanov, I. B.; Dwyer, J. R.; Sadighi, S.; Cramer, E. S.; Kosar, B.; Rassoul, H.</p> <p>2014-12-01</p> <p>In this presentation we will report on our first observations of energetic <span class="hlt">electron</span> <span class="hlt">flux</span> from inside thunderclouds. Energetic <span class="hlt">electrons</span> can produce high-energy radiation. High-energy radiation is routinely produced by thunderclouds and lightning. This radiation is in the form of x-rays and gamma-rays with timescales ranging from sub-microsecond (x-rays associated with lightning leaders), to sub-millisecond (Terrestrial Gamma ray Flashes), to minute long glows (Gamma-ray Glows from thunderclouds seen on the ground and in or near the cloud by aircrafts and balloons). It is generally accepted that these emissions originate from bremsstrahlung interactions of relativistic runaway <span class="hlt">electrons</span> with air, which can be accelerated in the thundercloud/lightning electric fields and gain up to multi-MeV energies. However, the exact physical details of the mechanism that produces these runaway <span class="hlt">electrons</span> are still unknown. Our balloon-borne campaign at Florida Tech is intended to directly measure the <span class="hlt">flux</span> of energetic <span class="hlt">electrons</span> inside thunderclouds. Each balloon carries two Geiger counters to record the energetic particles. Geiger counters are well suited for directly measuring energetic <span class="hlt">electrons</span> and positrons and have the advantage of being lightweight and dependable. Data from our payloads are saved onboard and also get transmitted in real time to our ground station at a transmission rate of 115.2 kb/s. This would provide us a high resolution radiation profile over a relatively large distance. This work was supported in part by the NASA grant NNX12A002H and by DARPA grant HR0011-1-10-1-0061.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25180079','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25180079"><span><span class="hlt">Electronic</span> cigarette effectiveness and abuse liability: predicting and regulating nicotine <span class="hlt">flux</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shihadeh, Alan; Eissenberg, Thomas</p> <p>2015-02-01</p> <p><span class="hlt">Electronic</span> cigarettes (ECIGs) comprise an aerosolized nicotine delivery product category that provides consumers with probably unprecedented control over extensive features and operating conditions, allowing a wide range of nicotine yields to be obtained. Depending on the combination of such ECIG variables as electrical power input, geometry, liquid composition, and puff behavior, ECIG users can extract in a few puffs far more or far less nicotine than with a conventional combustible cigarette. These features of ECIG design and use present challenges for public health policy, central among which is the question of how to regulate nicotine delivery. In this commentary, we propose a conceptual framework intended to provide a convenient approach for evaluating and regulating the nicotine emitted from ECIGs. This framework employs nicotine <span class="hlt">flux</span> to account for the total dose and rate at which nicotine reaches the user, 2 key factors in drug abuse liability. The nicotine <span class="hlt">flux</span> is the nicotine emitted per puff second (e.g., mg/s) by a given ECIG design under given use conditions, and it can be predicted accurately using physical principles. We speculate that if the <span class="hlt">flux</span> is too low, users likely will abandon the device and maintain conventional tobacco product use. Also, we speculate that if the <span class="hlt">flux</span> is too high, individuals may suffer toxic side effects and/or the device may have higher-than-necessary abuse liability. By considering ECIG design, operation conditions, liquid composition, and puff behavior variables in combination, we illustrate how ECIG specifications can be realistically mandated to result in a target <span class="hlt">flux</span> range. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950060553&hterms=Noriega&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DNoriega','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950060553&hterms=Noriega&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DNoriega"><span>Theoretical position-velocity diagrams of <span class="hlt">flux</span>, <span class="hlt">electron</span> density, and <span class="hlt">electron</span> temperature in Herbig-Haro objects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Indebetouw, Remy; Noriega-Crespo, Alberto</p> <p>1995-01-01</p> <p>Many features of Herbig-Haro objects can be reproduced using a kinematical bow shock model. We use the model to generate position-velocity (PV) diagrams of <span class="hlt">flux</span> in H-alpha (O I) lambda lambda 6300+63, (S II) lambda lambda 6716+31, (O III) lambda lambda 4959+5007, and (C I) lambda lambda 9823+50, line ratios of (O I)/H-alpha, (O I)/(S II), (S II)/H-alpha, H-alpha(S II), and (O III)/H-alpha, <span class="hlt">electron</span> density N(sub e), and <span class="hlt">electron</span> temperature T(sub e). We show how position-velocity diagrams of N(sub e) and <span class="hlt">flux</span> vary with shock velocity. By matching the diagrams from single lines, the line ratios, and N(sub e) with observations, we determined a narrow range of shock parameters for HH 1F, 2(A' + H), and 43 (B + C). We model the N(sub e) features of HH 2(A' + H) as a superposition of two bowshocks. We also show that the effects of slight misalignments of the two diagrams to be divided can produce artifacts in the line ratios and N(sub e) which obliterate the physical features. We show that N(sub e) in HH 1 can only be explained using the kinematical model by taking these misalignments into account.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28537305','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28537305"><span>Study of antiradical mechanisms with dihydroxybenzenes using reaction force and reaction <span class="hlt">electronic</span> <span class="hlt">flux</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ortega-Moo, Cristina; Durán, Rocio; Herrera, Bárbara; Gutiérrez-Oliva, Soledad; Toro-Labbé, Alejandro; Vargas, Rubicelia</p> <p>2017-06-07</p> <p>Phenolic compounds represent an important category of antioxidants because they help inhibit the oxidation process of organic compounds, while also acting as antiradicals in many biological processes. In this work, we analyze the transfer mechanisms for a set of catechols and resorcinols of a single <span class="hlt">electron</span>, proton and hydrogen, with the radical peroxyl (˙OOH) and with different <span class="hlt">electron</span> withdrawing and donating groups as substituents. By using the M05-2X exchange correlation functional within the Density Functional Theory framework combined with the 6-311++G(d,p) basis set, we were able to compute the Gibbs free energies for all mechanisms and compounds. According to the thermodynamic results, the hydrogen atom transfer mechanism was the most favorable. Therefore, this mechanism with substituents -CH3 and -COH in catechol and resorcinol was analyzed, using the reaction force and reaction <span class="hlt">electronic</span> <span class="hlt">flux</span> to characterize the structural and <span class="hlt">electronic</span> changes that take place during the reaction. Our results show that <span class="hlt">electron</span> donating groups favor <span class="hlt">electronic</span> changes along the reaction path, increasing the spontaneity of the hydrogen atom transfer mechanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM21A..02C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM21A..02C"><span>Van Allen Probes ECT/MagEIS Background Corrected <span class="hlt">Electron</span> <span class="hlt">Flux</span> Measurements: Methods and Initial Findings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Claudepierre, S. G.; O'Brien, T. P., III; Blake, J. B.; Fennell, J.; Looper, M. D.; Clemmons, J. H.; Roeder, J. L.; Mazur, J. E.; Mulligan, T. L.</p> <p>2014-12-01</p> <p>We present results from the Magnetic <span class="hlt">Electron</span> Ion Spectrometer (MagEIS) instrument, part ofthe Energetic Composition and Thermal Plasma (ECT) Suite, onboard the NASA Van AllenProbes spacecraft. The ECT/MagEIS instrument measures radiation belt <span class="hlt">electrons</span> in the ~20-4000 keV energy range and protons in the ~60-1000 keV energy range, with high resolution inboth energy and pitch-angle. In addition, the MagEIS <span class="hlt">electron</span> measurement technique allowsfor a full quantification of the source(s) of background contamination in the measurement.MagEIS is thus able to make clean, reliable <span class="hlt">electron</span> <span class="hlt">flux</span> observations in the presence of strongpenetrating backgrounds, for example, contamination from relativistic protons in the inner zoneand inner slot region. We summarize our background correction algorithm, describe the varioussources of background contamination, and present an overview of our initial findings using thebackground corrected data set. Understanding the causes and effects of backgroundcontamination in the MagEIS <span class="hlt">electron</span> data set is crucial for the interpretation and proper use ofsuch data. The techniques described will facilitate new investigations into the dynamics of theEarth's <span class="hlt">electron</span> radiation belts, which have thus far not been possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.8448B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.8448B"><span><span class="hlt">Electron</span> <span class="hlt">flux</span> dropouts at Geostationary Earth Orbit: Occurrences, magnitudes, and main driving factors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boynton, R. J.; Mourenas, D.; Balikhin, M. A.</p> <p>2016-09-01</p> <p>Large decreases of daily average <span class="hlt">electron</span> <span class="hlt">flux</span>, or dropouts, were investigated for a range of energies from 24.1 keV to 2.7 MeV, on the basis of a large database of 20 years of measurements from Los Alamos National Laboratory (LANL) geosynchronous satellites. Dropouts were defined as <span class="hlt">flux</span> decreases by at least a factor 4 in 1 day, or a factor 9 in 2 days during which a decrease by at least a factor of 2.5 must occur each day. Such decreases were automatically identified. As a first result, a comprehensive statistics of the mean waiting time between dropouts and of their mean magnitude has been provided as a function of <span class="hlt">electron</span> energy. Moreover, the Error Reduction Ratio analysis was applied to explore the possible nonlinear relationships between <span class="hlt">electron</span> dropouts and various exogenous factors, such as solar wind and geomagnetic indices. Different dropout occurrences and magnitudes were found in three distinct energy ranges, lower than 100 keV, 100-600 keV, and larger than 600 keV, corresponding to different groups of drivers and loss processes. Potential explanations have been outlined on the basis of the statistical results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvA..92f2706R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvA..92f2706R"><span>Modification of the quantum mechanical <span class="hlt">flux</span> formula for <span class="hlt">electron</span>-hydrogen ionization through Bohm's velocity field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Randazzo, J. M.; Ancarani, L. U.</p> <p>2015-12-01</p> <p>For the single differential cross section (SDCS) for hydrogen ionization by <span class="hlt">electron</span> impact (e -H problem), we propose a correction to the <span class="hlt">flux</span> formula given by R. Peterkop [Theory of Ionization of Atoms by <span class="hlt">Electron</span> Impact (Colorado Associated University Press, Boulder, 1977)]. The modification is based on an alternative way of defining the kinetic energy fraction, using Bohm's definition of velocities instead of the usual asymptotic kinematical, or geometrical, approximation. It turns out that the solution-dependent, modified energy fraction is equally related to the components of the probability <span class="hlt">flux</span>. Compared to what is usually observed, the correction yields a finite and well-behaved SDCS value in the asymmetrical situation where one of the continuum <span class="hlt">electrons</span> carries all the energy while the other has zero energy. We also discuss, within the S -wave model of the e -H ionization process, the continuity of the SDCS derivative at the equal energy sharing point, a property not so clearly observed in published benchmark results obtained with integral and S -matrix formulas with unequal final states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM21A2456P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM21A2456P"><span>ULF waves: the main periodicities and their relationships with solar wind structures and magnetospheric <span class="hlt">electron</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piersanti, M.; Alberti, T.; Lepreti, F.; Vecchio, A.; Villante, U.; Carbone, V.; Waters, C. L.</p> <p>2015-12-01</p> <p>We use high latitude ULF wave power in the range 2-7 mHz (Pc5 geomagnetic micropulsations), solar wind speed and dynamic pressure, and relativistic magnetospheric <span class="hlt">electron</span> <span class="hlt">flux</span> (E > 0.6 MeV), in the period January - September 2008, in order to detect typical periodicities and physical mechanisms involved into the solar wind-magnetosphere coupling during the declining phase of the 23th solar cycle. Using the Empirical Mode Decomposition (EMD) and applying a statistical test and cross-correlation analysis,we investigate the timescales and the physical mechanisms involved into the solar wind-magnetosphere coupling.Summarizing, we obtain the following results:1. We note the existence of two different timescales into the four datasets which are related to the short-term dynamics, with a characteristic timescale τ<3 days, and to the longer timescale dynamics, with a timescale between 7 and 80 days. The short-term variations could be related to the fluctuations around a characteristic mean value, while longer timescales dynamics can be associated with solar rotational periodicity and mechanisms regarding the occurrence of high-speed streams and corotating interaction regions but also with stream-stream interactions and synodic solar rotation.2. The cross-correlation analysis highlights the relevant role of the dynamical coupling between solar wind and magnetosphere via pressure balance and direct transfer of compressional waves into the magnetosphere. Moreover, it shows that the Kelvin-Helmholtz instability is not the primary source of geomagnetic ultra-low frequency wave activity. These results are in agreement with previous works [Engebretson et al, 1998].3. The cross-correlation coefficient between Pc5 wave power and relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> longscale reconstructions shows that Pc5 wave activity leads enhancements in magnetospheric <span class="hlt">electron</span> <span class="hlt">flux</span> to relativistic energy with a characteristic time delay of about 54 hours, which is in agreement with the lag of about 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22102203','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22102203"><span>Energy distribution of <span class="hlt">electron</span> <span class="hlt">flux</span> at electrodes in a low pressure capacitively coupled plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rauf, Shahid; Dorf, Leonid; Kenney, Jason; Collins, Ken</p> <p>2013-01-14</p> <p>A one-dimensional particle-in-cell (PIC) model is used to examine the energy distribution of <span class="hlt">electron</span> <span class="hlt">flux</span> at electrodes [labeled g{sub e}({epsilon},t), where {epsilon} is energy and t is time] in a low pressure 60 MHz capacitively coupled Ar discharge. The effect of gas pressure and an auxiliary DC voltage on g{sub e}({epsilon},t) is also investigated. It is found that the <span class="hlt">electrons</span> only leave the plasma for a short time period during the radio-frequency (RF) cycle when the sheath collapses at the electrode. Furthermore, majority of the exiting <span class="hlt">electrons</span> have energies below 10 eV with a distribution g{sub e}({epsilon},t) that is narrow in both energy and time. At relatively high pressures ({>=}4.67 Pa for the conditions considered), the relationship between the time-average distribution g{sub e}({epsilon}) and <span class="hlt">electron</span> temperature in the plasma (T{sub e}) can be easily established. Below 4.67 Pa, kinetic effects become important, making it difficult to interpret g{sub e}({epsilon}) in terms of T{sub e}. At low pressures, g{sub e}({epsilon},t) is found to broaden in both energy and time except for a narrow pressure range around 1.2 Pa where the distribution narrows temporally. These low pressure kinetic phenomena are observed when the <span class="hlt">electrons</span> can be accelerated by expanding sheaths to speeds that allow them to traverse the inter-electrode distance quickly (<1.5 RF cycles for conditions considered) and when <span class="hlt">electrons</span> undergo few collisions during this excursion. The mean energy of exiting <span class="hlt">electrons</span> increases with decreasing gas pressure, especially below 1.0 Pa, due to higher T{sub e} and secondary <span class="hlt">electrons</span> retaining a larger fraction of the energy they gained during initial sheath acceleration. For the relatively small DC voltages examined ( Double-Vertical-Line V{sub dc} Double-Vertical-Line /V{sub rf} {<=} 0.15), the application of a negative DC voltage on an electrode decreases the <span class="hlt">electron</span> <span class="hlt">flux</span> there but has a weak impact on the g{sub e} profile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......119R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......119R"><span>Oxygen <span class="hlt">flux</span> and dielectric response study of Mixed Ionic-<span class="hlt">Electronic</span> Conducting (MIEC) heterogeneous functional materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rabbi, Fazle</p> <p></p> <p>Dense mixed ionic-<span class="hlt">electronic</span> conducting (MIEC) membranes consisting of ionic conductive perovskite-type and/or fluorite-type oxides and high <span class="hlt">electronic</span> conductive spinel type oxides, at elevated temperature can play a useful role in a number of energy conversion related systems including the solid oxide fuel cell (SOFC), oxygen separation and permeation membranes, partial oxidization membrane reactors for natural gas processing, high temperature electrolysis cells, and others. This study will investigate the impact of different heterogeneous characteristics of dual phase ionic and <span class="hlt">electronic</span> conductive oxygen separation membranes on their transport mechanisms, in an attempt to develop a foundation for the rational design of such membranes. The dielectric behavior of a material can be an indicator for MIEC performance and can be incorporated into computational models of MIEC membranes in order to optimize the composition, microstructure, and ultimately predict long term membrane performance. The dielectric behavior of the MIECs can also be an indicator of the transport mechanisms and the parameters they are dependent upon. For this study we chose a dual phase MIEC oxygen separation membrane consisting of an ionic conducting phase: gadolinium doped ceria-Ce0.8 Gd0.2O2 (GDC) and an <span class="hlt">electronic</span> conductive phase: cobalt ferrite-CoFe2O4 (CFO). The membranes were fabricated from mixtures of Nano-powder of each of the phases for different volume percentages, sintered with various temperatures and sintering time to form systematic micro-structural variations, and characterized by structural analysis (XRD), and micro-structural analysis (SEM-EDS). Performance of the membranes was tested for variable partial pressures of oxygen across the membrane at temperatures from 850°C-1060°C using a Gas Chromatography (GC) system. Permeated oxygen did not directly correlate with change in percent mixture. An intermediate mixture 60%GDC-40%CFO had the highest <span class="hlt">flux</span> compared to the 50%GDC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5732854','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5732854"><span>Measurements of fluctuations in the <span class="hlt">flux</span> of runaway <span class="hlt">electrons</span> to the PLT tokamak limiter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barnes, C.W.; Strachan, J.D.</p> <p>1983-09-01</p> <p>Fluctuations in the <span class="hlt">flux</span> of runaway <span class="hlt">electrons</span> to the limiter are measured during many PLT (Princeton Large Torus) discharges. Oscillations at 60, 120, and 720 Hz are driven by variations in the vertical magnetic field which moves the plasma major radius. Fluctuations are seen with frequencies in the range of 2--20 kHz because of magnetohydrodynamic (MHD) magnetic islands which extend to the plasma surface. A continuous spectrum of fluctuations is observed up to 200 kHz which correlates with drift-wave turbulence. The magnitude of the driven fluctuations can be used to measure transport properties of the runaway <span class="hlt">electrons</span>. The amplitude of <span class="hlt">electron</span> motion due to the MHD and drift-wave oscillations, and hence a measure of the radial size of the instability, can be determined as a function of frequency. The slope of the frequency power spectrum of the drift-wave-induced fluctuations steepens with increasing runaway-<span class="hlt">electron</span> drift orbit displacement during the current drop at the end of the discharge, and as the power in the MHD oscillations increases. A magnetic probe is used to confirm the presence of oscillating magnetic fields capable of perturbing the <span class="hlt">electron</span> orbits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5183814','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5183814"><span>Measurements of fluctuations in the <span class="hlt">flux</span> of runaway <span class="hlt">electrons</span> to the PLT limiter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barnes, C.W.; Strachan, J.D.</p> <p>1982-07-01</p> <p>Fluctuations in the <span class="hlt">flux</span> of runaway <span class="hlt">electrons</span> to the limiter have been measured during many PLT discharges. Oscillations at 60, 120, and 720 Hz are driven by variations in the vertical magnetic field which moves the plasma major radius. Fluctuations are seen in the range of 2 ..-->.. 20 kHz due to MHD magnetic islands which extend to the plasma surface. A continuous spectrum of fluctuations is observed up to 200 kHz which correlates with drift-wave turbulence. The magnitude of the driven fluctuations can be used to measure transport properties of the runaway <span class="hlt">electrons</span>. The amplitude of <span class="hlt">electron</span> motion due to the MHD and drift-wave oscillations, and hence a measure of the radial size of the instability, can be determined as a function of frequency. The slope of the frequency power spectrum of the drift-wave-induced fluctuations steepens with increasing runaway <span class="hlt">electron</span> drift orbit displacement during the current drop at the end of the discharge, and as the power in the MHD oscillations increases. A magnetic probe was used to confirm the presence of oscillating magnetic fields capable of perturbing the <span class="hlt">electron</span> orbits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ApJ...684..790A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ApJ...684..790A"><span>An Upper Limit on the <span class="hlt">Electron</span>-Neutrino <span class="hlt">Flux</span> from the HiRes Detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abbasi, R. U.; Abu-Zayyad, T.; Allen, M.; Amann, J. F.; Archbold, G.; Belov, K.; Belz, J. W.; Ben Zvi, S. Y.; Bergman, D. R.; Biesiadecka, A.; Blake, S. A.; Boyer, J. H.; Brusova, O. A.; Burt, G. W.; Cannon, C.; Cao, Z.; Deng, W.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Gray, R. C.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G.; Hüntemeyer, P.; Ivanov, D.; Jones, B. F.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Knapp, B. C.; Loh, E. C.; Maestas, M. M.; Manago, N.; Mannel, E. J.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; Moore, S. A.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Roberts, M. D.; Rodriguez, D.; Sasaki, M.; Schnetzer, S. R.; Scott, L. M.; Seman, M.; Sinnis, G.; Smith, J. D.; Snow, R.; Sokolsky, P.; Song, C.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Wiencke, L. R.; Zech, A.; Zhang, X.</p> <p>2008-09-01</p> <p>Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultra-high-energy <span class="hlt">electron</span>-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current <span class="hlt">electron</span>-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular data set has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for <span class="hlt">electron</span>-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going <span class="hlt">electron</span>-neutrino-induced cascades and present an upper limit on the <span class="hlt">flux</span> of <span class="hlt">electron</span> neutrinos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..APR.B8007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..APR.B8007S"><span>An upper limit on the <span class="hlt">electron</span>-neutrino <span class="hlt">flux</span> from the HiRes detector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, Lauren</p> <p>2008-04-01</p> <p>Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy <span class="hlt">electron</span>-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current <span class="hlt">electron</span>-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for <span class="hlt">electron</span>-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going <span class="hlt">electron</span>-neutrino-induced cascades and present an upper limit on the <span class="hlt">flux</span> of <span class="hlt">electron</span>-neutrinos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ICRC....5.1377S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ICRC....5.1377S"><span>An upper limit on the <span class="hlt">electron</span>-neutrino <span class="hlt">flux</span> from the HiRes instrument</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, L. M.</p> <p></p> <p>Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) instrument are very sensitive to upward-going, Earth-skimming ultrahigh energy <span class="hlt">electron</span>-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and the Landau-Pomeranchuk-Migdal (LPM) effect, which is responsible for a significant decrease in the cross sections for bremsstrahlung and pair production, rendering charged-current <span class="hlt">electron</span>-neutrino-induced showers occurring deep in the Earth's crust detectable as they exit the Earth into the atmosphere. The search for upward-going neutrino-induced showers in the entire HiRes-II monocular dataset has yielded a null result. From a full LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for <span class="hlt">electron</span>-induced showers in rock, we calculate the resulting profile of these showers in air. A full detector Monte Carlo simulation to determine the detector response to upward-going <span class="hlt">electron</span>-neutrino-induced cascades is described and an upper limit on the <span class="hlt">flux</span> of <span class="hlt">electron</span>-neutrinos is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760008619&hterms=qualitative+observation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dqualitative%2Bobservation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760008619&hterms=qualitative+observation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dqualitative%2Bobservation"><span>Coordinated ATS-5 <span class="hlt">electron</span> <span class="hlt">flux</span> and simultaneous auroral observations, appendix B. [of magnetic storms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mende, S. B.; Shelley, E. G.</p> <p>1975-01-01</p> <p>All Sky Cameras (ASCA) magnetosphere observations were made at the field line conjugate of the ATS-5 Satellite. The magnetosphere region examined was L=5 to L=11. The correlation of the auroras observed by the ASCA's and the magnetospheric trapped <span class="hlt">fluxes</span> was studied. It is shown that auroral forms are not simply correlated with the synchronous altitude <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The presence of hot plasma at the ATS-5 satellite is a necessary but not sufficient condition for the occurrence of local auroras. On quiet days the hot plasma does not penetrate into the magnetosphere far enough to reach the ATS-5 orbit. Under these conditions no auroras are observed at the field line conjugate, but auroras are usually observed on higher latitude field lines. On more disturbed days, auroral arcs are observed at lower latitudes when the plasma sheet penetrates into the ATS-5 orbit. Significant qualitative correlation between the ASCA data and the trapped <span class="hlt">fluxes</span> was observed when a local plasma injection event occurred near ATS-5. Magnetograms are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvS..16l0701Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvS..16l0701Y"><span>Maximizing spectral <span class="hlt">flux</span> from self-seeding hard x-ray free <span class="hlt">electron</span> lasers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Xi; Shvyd'ko, Yuri</p> <p>2013-12-01</p> <p>Fully coherent x rays can be generated by self-seeding x-ray free <span class="hlt">electron</span> lasers (XFELs). Self-seeding by a forward Bragg diffraction (FBD) monochromator has been recently proposed [G. Geloni, V. Kocharyan, and E. Saldin, J. Mod. Opt. 58, 1391 (2011)JMOPEW0950-034010.1080/09500340.2011.586473] and demonstrated [J. Amann , Nat. Photonics 6, 693 (2012)NPAHBY1749-488510.1038/nphoton.2012.180]. Characteristic time T0 of FBD determines the power, spectral, and time characteristics of the FBD seed [Yu. Shvyd’ko and R. Lindberg, Phys. Rev. ST Accel. Beams 15, 100702 (2012)PRABFM1098-440210.1103/PhysRevSTAB.15.100702]. Here we show that for a given <span class="hlt">electron</span> bunch with duration σe the spectral <span class="hlt">flux</span> of the self-seeding XFEL can be maximized, and the spectral bandwidth can be respectively minimized by choosing T0˜σe/π and by optimizing the <span class="hlt">electron</span> bunch delay τe. The choices of T0 and τe are not unique. In all cases, the maximum value of the spectral <span class="hlt">flux</span> and the minimum bandwidth are primarily determined by σe. Two-color seeding takes place if T0≪σe/π. The studies are performed, for a Gaussian <span class="hlt">electron</span> bunch distribution with the parameters, close to those used in the short-bunch (σe≃5fs) and long-bunch (σe≃20fs) operation modes of the Linac Coherent Light Source XFEL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRA..118.7810R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRA..118.7810R"><span>Comparison between POES energetic <span class="hlt">electron</span> precipitation observations and riometer absorptions: Implications for determining true precipitation <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodger, Craig J.; Kavanagh, Andrew J.; Clilverd, Mark A.; Marple, Steve R.</p> <p>2013-12-01</p> <p><span class="hlt">electron</span> precipitation (EEP) impacts the chemistry of the middle atmosphere with growing evidence of coupling to surface temperatures at high latitudes. To better understand this link, it is essential to have realistic observations to properly characterize precipitation and which can be incorporated into chemistry-climate models. The Polar-orbiting Operational Environmental Satellite (POES) detectors measure precipitating particles but only integral <span class="hlt">fluxes</span> and only in a fraction of the bounce loss cone. Ground-based riometers respond to precipitation from the whole bounce loss cone; they measure the cosmic radio noise absorption (CNA), a qualitative proxy with scant direct information on the energy <span class="hlt">flux</span> of EEP. POES observations should have a direct relationship with ΔCNA and comparing the two will clarify their utility in studies of atmospheric change. We determined ionospheric changes produced by the EEP measured by the POES spacecraft in ~250 overpasses of an imaging riometer in northern Finland. The ΔCNA modeled from the POES data is 10-15 times less than the observed ΔCNA when the >30 keV <span class="hlt">flux</span> is reported as <106 cm-2 s-1 sr-1. Above this level, there is relatively good agreement between the space-based and ground-based measurements. The discrepancy occurs mostly during periods of low geomagnetic activity, and we contend that weak diffusion is dominating the pitch angle scattering into the bounce loss cone at these times. A correction to the calculation using measurements of the trapped <span class="hlt">flux</span> considerably reduces the discrepancy and provides further support to our hypothesis that weak diffusion leads to underestimates of the EEP.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5739214','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5739214"><span>Comparison of precipitating <span class="hlt">electron</span> energy <span class="hlt">flux</span> on March 22, 1979 with an empirical model: CDAW-6</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Simons S.L. Jr.; Reiff, P.H.; Spiro, R.W.; Hardy, D.A.; Kroehl, H.W.</p> <p>1985-03-01</p> <p>Data recorded by Defense Meterological Satellite Program, TIROS and P-78-1 satellites for the CDAW 6 event on March 22, 1979, have been compared with a statistical model of precipitating <span class="hlt">electron</span> <span class="hlt">fluxes</span>. Comparisons have been made on both an orbit-by-orbit basis and on a global basis by sorting and binning the data by AE index, invariant latitude and magnetic local time in a manner similar to which the model was generated. We conclude that the model <span class="hlt">flux</span> agrees with the data to within a factor of two, although small features and the exact locations of features are not consistently reproduced. In addition, the latitude of highest <span class="hlt">electron</span> precipitation usually occurs about 3/sup 0/ more pole-ward in the model than in the data. We attribute this discrepancy to ring current inflation of the storm time magnetosphere (as evidenced by negative Dst's). We suggest that a similar empirical model based on AL instead of AE and including some indicator of the history of the event would provide an even better comparison. Alternatively, in situ data such as electrojet location should be used routinely to normalize the latitude of the auroral precipitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810017461&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Denergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810017461&hterms=energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D90%26Ntt%3Denergy"><span>A satellite investigation of energy <span class="hlt">flux</span> and inferred potential drop in auroral <span class="hlt">electron</span> energy spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meniett, J. D.; Burch, J. L.</p> <p>1981-01-01</p> <p>Because predicted relationship (epsilon directly varies with V squared) between auroral <span class="hlt">electron</span> energy <span class="hlt">flux</span> (epsilon) and the inferred acceleration potential drop (V) for accelerated Maxwellian distributions was favorably tested by other using sounding rocket data for the limiting case of eVE 1 (where Ec is the characteristic energy of the accelerated Maxwellian distribution) and for a single inverted-V observed by the Injun 5 satellite, data from Atmosphere D were used to extend these studies over the range .2 eV/Ec 5 and for a wide range of latitudes and local times on both the nightside and the dayside. Results show good agreement with the full accelerated Maxwellian model. An analytical approximation to the <span class="hlt">electron</span> energy <span class="hlt">flux</span> was derived which better describes the data over the range .2 eV/Ec approximated 3. Analyses of individual energy spectra at small and large pitch angles through well-defined inverted-V structures suggest that the altitude of the inferred potential drop maximizes near the center of the inverted-V's.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.4306G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.4306G"><span>Computing uncertainties in ionosphere-airglow models: I. <span class="hlt">Electron</span> <span class="hlt">flux</span> and species production uncertainties for Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gronoff, Guillaume; Simon Wedlund, Cyril; Mertens, Christopher J.; Lillis, Robert J.</p> <p>2012-04-01</p> <p>The ionization and excitation of atoms and molecules in the upper atmospheres of the Earth and planets are computed by a number of physical models. From these calculations, quantities measurable by dedicated satellite experiments such as airglow and <span class="hlt">electron</span> <span class="hlt">fluxes</span> can be derived. It is then possible to compare model and observation to derive more fundamental physical properties of the upper atmospheres, for example, the density as a function of altitude. To ensure the accuracy of these retrieval techniques, it is important to have an estimation of the uncertainty of these models and to have ways to account for these uncertainties. The complexity of kinetic models for computing the secondary production of excited state species (including ions) makes it a difficult evaluation, and studies usually neglect or underestimate it. We present here a Monte-Carlo approach to the computation of model uncertainties. As an example, we studied several aspects of the model uncertainties in the upper atmosphere of Mars, including the computed secondary <span class="hlt">electron</span> <span class="hlt">flux</span> and the production of the main ion species. Our simulations show the importance of improving solar <span class="hlt">flux</span> models, especially on the energy binning and on the photon impact cross sections, which are the main sources of uncertainties on the dayside. The risk of modifying cross sections on the basis of aeronomical observations is highlighted for the case of Mars, while accurate uncertainties are shown to be crucial for the interpretation of data from the particle detectors onboard Mars Global Surveyor. Finally, it shows the importance of AtMoCiad, a public database dedicated to the evaluation of aeronomy cross section uncertainties. A detailed study of the resulting emissions cross sections uncertainties is the focus of a forthcoming paper (Gronoff et al., 2012) in which the outputs discussed in the present paper are used to compute airglow uncertainty, and the overall result is compared with the data from the SPICAM UV</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SuScT..30d4002Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SuScT..30d4002Z"><span>A nanocryotron comparator can connect single-<span class="hlt">flux</span>-quantum circuits to conventional <span class="hlt">electronics</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Qing-Yuan; McCaughan, Adam N.; Dane, Andrew E.; Berggren, Karl K.; Ortlepp, Thomas</p> <p>2017-04-01</p> <p>Integration with conventional <span class="hlt">electronics</span> offers a straightforward and economical approach to upgrading existing superconducting technologies, such as scaling up superconducting detectors into large arrays and combining single <span class="hlt">flux</span> quantum (SFQ) digital circuits with semiconductor logic gates and memories. However, direct output signals from superconducting devices (e.g., Josephson junctions) are usually not compatible with the input requirements of conventional devices (e.g., transistors). Here, we demonstrate the use of a single three-terminal superconducting-nanowire device, called the nanocryotron (nTron), as a digital comparator to combine SFQ circuits with mature semiconductor circuits such as complementary metal oxide semiconductor (CMOS) circuits. Since SFQ circuits can digitize output signals from general superconducting devices and CMOS circuits can interface existing CMOS-compatible <span class="hlt">electronics</span>, our results demonstrate the feasibility of a general architecture that uses an nTron as an interface to realize a ‘super-hybrid’ system consisting of superconducting detectors, superconducting quantum <span class="hlt">electronics</span>, CMOS logic gates and memories, and other conventional <span class="hlt">electronics</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM31A2446S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM31A2446S"><span>Combined effects of ULF, VLF, and EMIC Waves, Substorms, and Solar Wind Parameters on Relativistic <span class="hlt">Electron</span> <span class="hlt">Flux</span>: Multiple Regression Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simms, L. E.; Engebretson, M. J.; Rodger, C. J.; Gjerloev, J. W.; Lessard, M.; Clilverd, M. A.; Pilipenko, V.; Reeves, G. D.</p> <p>2016-12-01</p> <p>Relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> may be influenced by energy inputs from the solar wind (velocity, number density, and IMF Bz), substorm activity, source and seed <span class="hlt">electron</span> populations (tens of keV and hundreds of keV, respectively), as well as by the ULF, VLF, and EMIC waves triggered by these factors. As all these variables are intercorrelated, we use multiple regression analyses to determine which are most influential when other factors are controlled. For the years 2005-2011, we use daily averages of LANL geostationary orbit <span class="hlt">electron</span> data (three high energy channels, as well as source and seed <span class="hlt">electrons</span>), number of substorms per day from the SUPERMAG substorm list, a ULF index from ground magnetometers, lower band whistler mode chorus power (VLF) observed by the DEMETER satellite, and EMIC (< 1 Hz) wave data from the Halley ground station. The correlations found in the linear multiple regression support several hypotheses. ULF and VLF waves enhance the 1.8-3.5 MeV <span class="hlt">electron</span> <span class="hlt">flux</span> but their effect falls off (or becomes negative) on higher energy <span class="hlt">fluxes</span> (3.5-6.0 and 6.0-7.8 MeV). EMIC waves reduce high energy <span class="hlt">electron</span> <span class="hlt">flux</span> mainly in the highest energy channel (6.0-7.8 MeV); their effect on the lower 1.8-3.5 MeV channel is minimal. A higher number of substorms in a day also enhance relativistic <span class="hlt">electron</span> <span class="hlt">flux</span>, with more impact at higher energy channels. We explore the relations between these parameters using path analysis to determine the mechanisms driving wave power which subsequently impact <span class="hlt">flux</span> levels. We also assess the predictive ability of these models in forecasting <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990KosIs..28..623G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990KosIs..28..623G"><span>Mean <span class="hlt">fluxes</span> of <span class="hlt">electrons</span> and protons with energies of 1-20 keV on polar-satellite trajectories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Getselev, I. V.; Gubar', Iu. I.; Kropotkin, A. P.; Mart'ianov, S. A.; Timofeev, G. A.</p> <p>1990-07-01</p> <p>It is pointed out that 1-20-keV <span class="hlt">electron</span> and proton <span class="hlt">fluxes</span> have a significant effect on spacecraft surface layers in space. Mean spectra of 1-20 keV <span class="hlt">electrons</span> and protons have been determined for polar-satellite trajectories at heights ranging from 500 to 1000 km for orbital inclinations of 50, 65, and 80-100 deg.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..93r4302M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..93r4302M"><span>Systematic <span class="hlt">electronic</span>-structure investigation of substitutional impurity diffusion and <span class="hlt">flux</span> coupling in bcc iron</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Messina, Luca; Nastar, Maylise; Sandberg, Nils; Olsson, Pär</p> <p>2016-05-01</p> <p>The diffusion properties of a wide range of impurities (transition metals and Al, Si, and P) in ferritic alloys are here investigated by means of a combined ab initio-atomic diffusion theory approach. The <span class="hlt">flux</span>-coupling mechanisms and the solute-diffusion coefficients are inferred from <span class="hlt">electronic</span>-structure calculations of solute-defect interactions and microscopic jump frequencies. All properties except the second-nearest-neighbor binding energy are found to have a characteristic bell shape as a function of the d -band filling for the 4 d and 5 d series, and an M shape for the 3 d row because of the out-of-trend behavior of Mn. The solute jump frequencies are governed by compressibility, which makes diffusion of large solutes faster, although this effect is partially compensated for by lower attempt frequencies and larger correlations with the vacancy. Diffusion coefficients are predicted in a wide temperature range, far below the experimentally accessible temperatures. In accordance with experiments, Co is found to be a slow diffuser in iron, and the same behavior is predicted for Re, Os, and Ir impurities. Finally, <span class="hlt">flux</span>-coupling phenomena depend on the iron jump frequencies next to a solute atom, which are mainly controlled by similar <span class="hlt">electronic</span> interactions to those determining the binding energies. Vacancy drag and solute enrichment at sinks systematically arise below a solute-dependent temperature threshold, directly correlated with the <span class="hlt">electronic</span>-level interactions at the equilibrium and the saddle-point states. Early transition metals with repulsive second-nearest-neighbor interactions also diffuse via vacancy drag, although they show a lower temperature threshold than the late metals. This confirms that drag is the most common solute-vacancy coupling mechanism in iron at low temperatures, and this is likely to be confirmed as well for impurity diffusion in other transition metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760061664&hterms=min&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmin','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760061664&hterms=min&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmin"><span>The 2- to 12-min quasi-periodic variation of 50- to 1000-keV trapped <span class="hlt">electron</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, C. S.; Parks, G. K.; Winckler, J. R.</p> <p>1976-01-01</p> <p>It was previously shown that trapped <span class="hlt">electron</span> <span class="hlt">fluxes</span> of energies in the range from 50 keV to 1 MeV observed in the afternoon magnetosphere during substorms frequently undergo periodic variations. High-resolution <span class="hlt">electron</span> spectrometer data indicate that these <span class="hlt">electron</span> variations are periodic in the range of about 2-12 min, correlated with magnetic field variations, organized by the local magnetic field, and dependent on pitch angle. The observations suggest that the <span class="hlt">electron</span> variations are adiabatic. The study derives quantitative adiabatic expressions of particle <span class="hlt">flux</span> variations in a model geomagnetic field perturbation to show that the observational features are consistent with effects arising from adiabatic modulation of trapped particle <span class="hlt">fluxes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.6386W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.6386W"><span>The effects and correction of the geometric factor for the POES/MEPED <span class="hlt">electron</span> <span class="hlt">flux</span> instrument using a multisatellite comparison</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whittaker, Ian C.; Rodger, Craig J.; Clilverd, Mark A.; Sauvaud, Jean-André</p> <p>2014-08-01</p> <p>Measurements from the Polar-Orbiting Environmental Satellite (POES) Medium Energy Proton and <span class="hlt">Electron</span> Detector (MEPED) instrument are widely used in studies into radiation belt dynamics and atmospheric coupling. However, this instrument has been shown to have a complex energy-dependent response to incident particle <span class="hlt">fluxes</span>, with the additional possibility of low-energy protons contaminating the <span class="hlt">electron</span> <span class="hlt">fluxes</span>. We test the recent Monte Carlo theoretical simulation of the instrument by comparing the responses against observations from an independent experimental data set. Our study examines the reported geometric factors for the MEPED <span class="hlt">electron</span> <span class="hlt">flux</span> instrument against the high-energy resolution Instrument for Detecting Particles (IDPs) on the Detection of Electromagnetic Emissions Transmitted from Earthquake Regions satellite when they are located at similar locations and times, thereby viewing the same quasi-trapped population of <span class="hlt">electrons</span>. We find that the new Monte Carlo-produced geometric factors accurately describe the response of the POES MEPED instrument. We go on to develop a set of equations such that integral <span class="hlt">electron</span> <span class="hlt">fluxes</span> of a higher accuracy are obtained from the existing MEPED observations. These new MEPED integral <span class="hlt">fluxes</span> correlated very well with those from the IDP instrument (>99.9% confidence level). As part of this study we have also tested a commonly used algorithm for removing proton contamination from MEPED instrument observations. We show that the algorithm is effective, providing confirmation that previous work using this correction method is valid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3068929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3068929"><span>Reactive Oxygen Species Production by Forward and Reverse <span class="hlt">Electron</span> <span class="hlt">Fluxes</span> in the Mitochondrial Respiratory Chain</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Selivanov, Vitaly A.; Votyakova, Tatyana V.; Pivtoraiko, Violetta N.; Zeak, Jennifer; Sukhomlin, Tatiana; Trucco, Massimo; Roca, Josep; Cascante, Marta</p> <p>2011-01-01</p> <p>Reactive oxygen species (ROS) produced in the mitochondrial respiratory chain (RC) are primary signals that modulate cellular adaptation to environment, and are also destructive factors that damage cells under the conditions of hypoxia/reoxygenation relevant for various systemic diseases or transplantation. The important role of ROS in cell survival requires detailed investigation of mechanism and determinants of ROS production. To perform such an investigation we extended our rule-based model of complex III in order to account for <span class="hlt">electron</span> transport in the whole RC coupled to proton translocation, transmembrane electrochemical potential generation, TCA cycle reactions, and substrate transport to mitochondria. It fits respiratory <span class="hlt">electron</span> <span class="hlt">fluxes</span> measured in rat brain mitochondria fueled by succinate or pyruvate and malate, and the dynamics of NAD+ reduction by reverse <span class="hlt">electron</span> transport from succinate through complex I. The fitting of measured characteristics gave an insight into the mechanism of underlying processes governing the formation of free radicals that can transfer an unpaired <span class="hlt">electron</span> to oxygen-producing superoxide and thus can initiate the generation of ROS. Our analysis revealed an association of ROS production with levels of specific radicals of individual <span class="hlt">electron</span> transporters and their combinations in species of complexes I and III. It was found that the phenomenon of bistability, revealed previously as a property of complex III, remains valid for the whole RC. The conditions for switching to a state with a high content of free radicals in complex III were predicted based on theoretical analysis and were confirmed experimentally. These findings provide a new insight into the mechanisms of ROS production in RC. PMID:21483483</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4375552','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4375552"><span>A Well-Balanced Preexisting Equilibrium Governs <span class="hlt">Electron</span> <span class="hlt">Flux</span> Efficiency of a Multidomain Diflavin Reductase</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Frances, Oriane; Fatemi, Fataneh; Pompon, Denis; Guittet, Eric; Sizun, Christina; Pérez, Javier; Lescop, Ewen; Truan, Gilles</p> <p>2015-01-01</p> <p>Diflavin reductases are bidomain <span class="hlt">electron</span> transfer proteins in which structural reorientation is necessary to account for the various intramolecular and intermolecular <span class="hlt">electron</span> transfer steps. Using small-angle x-ray scattering and nuclear magnetic resonance data, we describe the conformational free-energy landscape of the NADPH-cytochrome P450 reductase (CPR), a typical bidomain redox enzyme composed of two covalently-bound flavin domains, under various experimental conditions. The CPR enzyme exists in a salt- and pH-dependent rapid equilibrium between a previously described rigid, locked state and a newly characterized, highly flexible, unlocked state. We further establish that maximal <span class="hlt">electron</span> <span class="hlt">flux</span> through CPR is conditioned by adjustable stability of the locked-state domain interface under resting conditions. This is rationalized by a kinetic scheme coupling rapid conformational sampling and slow chemical reaction rates. Regulated domain interface stability associated with fast stochastic domain contacts during the catalytic cycle thus provides, to our knowledge, a new paradigm for improving our understanding of multidomain enzyme function. PMID:25809265</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhD...49WLT01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhD...49WLT01L"><span><span class="hlt">Electron</span> heating and particle <span class="hlt">fluxes</span> in dual frequency atmospheric-pressure helium capacitive discharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Dingxin; Yang, Aijun; Wang, Xiaohua; Chen, Chen; Rong, Mingzhe; Kong, Michael G.</p> <p>2016-12-01</p> <p>In this letter, a 1D fluid model has been used to study the <span class="hlt">electron</span> heating and particle transport in dual frequency atmospheric-pressure helium capacitive discharge with a high-frequency (HF) voltage of 10 MHz and a low-frequency (LF) voltage of 1 MHz. The electric field is decoupled to three components: the HF, the LF and the direct current (DC) ones, and they have much different effects on the plasmas. The eletrons in plasma bulk are mainly heated by the HF electric field, while in plasma sheath they are heated and cooled by the LF and DC electric fields, respectively. With a fixed total input power, the increase of LF power leads to great enhancement of the electrode <span class="hlt">fluxes</span> of <span class="hlt">electrons</span> and ions, especially for the energetic <span class="hlt">electrons</span> of T e  >  2 eV, because more power is dissipated in the vicinity of electrodes and the inelastic collision is more pronounced. Therefore, the particle transport on the treated sample can be greatly enhanced without additional gas heating in dual frequency plasmas, which meets the application requirements more compared to the single frequency plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912799A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912799A"><span>New homogeneous composite of energetic <span class="hlt">electron</span> <span class="hlt">fluxes</span> from NOAA/POES satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asikainen, Timo; Ruopsa, Miro</p> <p>2017-04-01</p> <p>One of the most widely popular datasets of energetic particles used in, e.g., long-term radiation belt studies and in atmospheric/climate studies is perhaps the NOAA/POES (Polar Orbiting Environmental Satellites) dataset, which is unique in its length extending nearly continuously from 1979 to present. However, it has been long recognized that the energetic particle measurements by the MEPED instrument (Medium Energy Proton and <span class="hlt">Electron</span> Detector) onboard the POES satellites has numerous instrumental problems, which have made quantitative estimates of energetic particle <span class="hlt">fluxes</span> somewhat difficult. In the recent years a lot of effort has been put in understanding and correcting these instrumental deficiencies, and as a result we have produced a dataset, which corrects instrumental degradation, <span class="hlt">electronic</span> noise and various sensitivity and contamination issues. However, here we show that there are also other remaining factors, not related to instrument construction, which still cause the 37 year POES dataset to be significantly inhomogeneous. One inhomogeneity is caused by the drift in the orientation of the satellite orbital planes over long periods of time. Another, even more serious issue, is the difference in the orientation of the particle telescopes between the satellites flown before mid-1998 (SEM-1 era) and after that (SEM-2 era). Here we discuss these effects and how the data can be corrected for them. We present a new homogenized composite data series, which yields the latitudinal distribution of energetic <span class="hlt">electrons</span> from 1979 to present with daily time resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPYO4008Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPYO4008Y"><span>Statistics of field-aligned intermittent <span class="hlt">electron</span> <span class="hlt">flux</span> in a linear ECR plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshimura, Shinji; Terasaka, Kenichiro; Aramaki, Mitsutoshi; Tanaka, Masayoshi Y.</p> <p>2012-10-01</p> <p>Spontaneous emission of field-aligned intermittent high-energy <span class="hlt">electron</span> <span class="hlt">flux</span> has been observed in a linear <span class="hlt">electron</span>-cyclotron-resonance (ECR) plasma produced in the HYPER-I device (NIFS, Japan). We utilized the temporal variation of probe's floating potential due to <span class="hlt">electron</span> influx as an index of the intermittent events. Time series of the floating potential fluctuation have been analyzed statistically. The probability density function (PDF) exhibits a non-Gaussian distribution with a long tail in the negative amplitude side, indicating that the signal is dominated by large amplitude negative spikes. The frequency distribution of waiting time, which is defined by the time interval between two consecutive spikes, is well fitted by an exponential distribution, implying a probable connection to the stationary Poisson process. Although a power-law dependence is found in the duration distribution, its relation to the self-organized criticality has not been clear. The effect of ion species on the statistics above will also be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25809265','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25809265"><span>A well-balanced preexisting equilibrium governs <span class="hlt">electron</span> <span class="hlt">flux</span> efficiency of a multidomain diflavin reductase.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Frances, Oriane; Fatemi, Fataneh; Pompon, Denis; Guittet, Eric; Sizun, Christina; Pérez, Javier; Lescop, Ewen; Truan, Gilles</p> <p>2015-03-24</p> <p>Diflavin reductases are bidomain <span class="hlt">electron</span> transfer proteins in which structural reorientation is necessary to account for the various intramolecular and intermolecular <span class="hlt">electron</span> transfer steps. Using small-angle x-ray scattering and nuclear magnetic resonance data, we describe the conformational free-energy landscape of the NADPH-cytochrome P450 reductase (CPR), a typical bidomain redox enzyme composed of two covalently-bound flavin domains, under various experimental conditions. The CPR enzyme exists in a salt- and pH-dependent rapid equilibrium between a previously described rigid, locked state and a newly characterized, highly flexible, unlocked state. We further establish that maximal <span class="hlt">electron</span> <span class="hlt">flux</span> through CPR is conditioned by adjustable stability of the locked-state domain interface under resting conditions. This is rationalized by a kinetic scheme coupling rapid conformational sampling and slow chemical reaction rates. Regulated domain interface stability associated with fast stochastic domain contacts during the catalytic cycle thus provides, to our knowledge, a new paradigm for improving our understanding of multidomain enzyme function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002394&hterms=cluster&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcluster','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002394&hterms=cluster&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcluster"><span>Van Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC Waves, ULF Pulsations, and an <span class="hlt">Electron</span> <span class="hlt">Flux</span> Dropout</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; Macdowall, R.; Spence, H.; Reeves, G.; Blake, J. B.; Baker, D. N.; Green, J. C.; Singer, H. J.; Carr, C.; Santolík, O.</p> <p>2016-01-01</p> <p>We examined an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout during the 12-14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A (P5), Cluster 2, and Geostationary Operational Environmental Satellites (GOES) 13, 14, and 15. The <span class="hlt">electron</span> <span class="hlt">fluxes</span> for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 h from 12 to 14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The first interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 12-13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ electromagnetic ion cyclotron (EMIC) waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 13-14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst<100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> finally returned to near prestorm values, possibly in response to strong ultralow frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed <span class="hlt">electron</span> behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.1990S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.1990S"><span>Van Allen Probes, THEMIS, GOES, and Cluster observations of EMIC waves, ULF pulsations, and an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; MacDowall, R.; Spence, H.; Reeves, G.; Blake, J. B.; Baker, D. N.; Green, J. C.; Singer, H. J.; Carr, C.; Santolík, O.</p> <p>2016-03-01</p> <p>We examined an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout during the 12-14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A (P5), Cluster 2, and Geostationary Operational Environmental Satellites (GOES) 13, 14, and 15. The <span class="hlt">electron</span> <span class="hlt">fluxes</span> for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 h from 12 to 14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The first interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 12-13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ electromagnetic ion cyclotron (EMIC) waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 13-14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst < -100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> finally returned to near prestorm values, possibly in response to strong ultralow frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed <span class="hlt">electron</span> behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170002394&hterms=allen&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dallen','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170002394&hterms=allen&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dallen"><span>Van Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC Waves, ULF Pulsations, and an <span class="hlt">Electron</span> <span class="hlt">Flux</span> Dropout</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; Macdowall, R.; Spence, H.; Reeves, G.; Blake, J. B.; Baker, D. N.; Green, J. C.; Singer, H. J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170002394'); toggleEditAbsImage('author_20170002394_show'); toggleEditAbsImage('author_20170002394_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170002394_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170002394_hide"></p> <p>2016-01-01</p> <p>We examined an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout during the 12-14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A (P5), Cluster 2, and Geostationary Operational Environmental Satellites (GOES) 13, 14, and 15. The <span class="hlt">electron</span> <span class="hlt">fluxes</span> for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 h from 12 to 14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The first interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 12-13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ electromagnetic ion cyclotron (EMIC) waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 13-14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst<100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> finally returned to near prestorm values, possibly in response to strong ultralow frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed <span class="hlt">electron</span> behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1258442','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1258442"><span>Van Allen Probes, THEMIS, GOES, and cluster observations of EMIC waves, ULF pulsations, and an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; MacDowall, R.; Spence, H.; Reeves, G.; Blake, J. B.; Baker, D. N.; Green, J. C.; Singer, H. J.; Carr, C.; Santolik, O.</p> <p>2016-03-04</p> <p>We examined an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout during the 12–14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A (P5), Cluster 2, and Geostationary Operational Environmental Satellites (GOES) 13, 14, and 15. The <span class="hlt">electron</span> <span class="hlt">fluxes</span> for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 h from 12 to 14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The first interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 12–13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He<sup>+</sup> electromagnetic ion cyclotron (EMIC) waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 13–14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst <–100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> finally returned to near prestorm values, possibly in response to strong ultralow frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed <span class="hlt">electron</span> behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1258442-van-allen-probes-themis-goes-cluster-observations-emic-waves-ulf-pulsations-electron-flux-dropout','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1258442-van-allen-probes-themis-goes-cluster-observations-emic-waves-ulf-pulsations-electron-flux-dropout"><span>Van Allen Probes, THEMIS, GOES, and cluster observations of EMIC waves, ULF pulsations, and an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; ...</p> <p>2016-03-04</p> <p>We examined an <span class="hlt">electron</span> <span class="hlt">flux</span> dropout during the 12–14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A (P5), Cluster 2, and Geostationary Operational Environmental Satellites (GOES) 13, 14, and 15. The <span class="hlt">electron</span> <span class="hlt">fluxes</span> for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 h from 12 to 14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervalsmore » of reduced <span class="hlt">electron</span> <span class="hlt">fluxes</span>. The first interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 12–13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ electromagnetic ion cyclotron (EMIC) waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> on 13–14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst <–100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV <span class="hlt">electron</span> <span class="hlt">fluxes</span> finally returned to near prestorm values, possibly in response to strong ultralow frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed <span class="hlt">electron</span> behavior.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22365532','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22365532"><span><span class="hlt">ELECTRON</span> HEAT <span class="hlt">FLUX</span> IN THE SOLAR WIND: ARE WE OBSERVING THE COLLISIONAL LIMIT IN THE 1 AU DATA?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Landi, S.; Matteini, L.; Pantellini, F.</p> <p>2014-07-20</p> <p>Using statistically significant data at 1 AU, it has recently been shown (Bale et al.) that in the solar wind, when the Knudsen number K {sub T} (the ratio between the <span class="hlt">electron</span> mean free path and the <span class="hlt">electron</span> temperature scale height) drops below about 0.3, the <span class="hlt">electron</span> heat <span class="hlt">flux</span> q intensity rapidly approaches the classical collisional Spitzer-Härm limit. Using a fully kinetic model including the effect of Coulomb collisions and the expansion of the solar wind with heliocentric distance, we observe that the heat <span class="hlt">flux</span> strength does indeed approach the collisional value for Knudsen numbers smaller than about 0.3 in very good agreement with the observations. However, closer inspection of the heat <span class="hlt">flux</span> properties, such as its variation with the heliocentric distance and its dependence on the plasma parameters, shows that for Knudsen numbers between 0.02 and 0.3 the heat <span class="hlt">flux</span> is not conveniently described by the Spitzer-Härm formula. We conclude that even though observations at 1 AU seem to indicate that the <span class="hlt">electron</span> heat <span class="hlt">flux</span> intensity approaches the collisional limit when the Knudsen drops below ∼0.3, the collisional limit is not a generally valid closure for a Knudsen larger than 0.01. Moreover, the good agreement between the heat <span class="hlt">flux</span> from our model and the heat <span class="hlt">flux</span> from solar wind measurements in the high-Knudsen number regime seems to indicate that the heat <span class="hlt">flux</span> at 1 AU is not constrained by electromagnetic instabilities as both wave-particle and wave-wave interactions are neglected in our calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770026467','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770026467"><span>Surface charge kinetics near metal-dielectric interfaces exposed to kilovolt <span class="hlt">electron</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robinson, J. W.</p> <p>1977-01-01</p> <p>Interfaces between dielectric films and grounded metallic boundaries were exposed, in vacuum, to monoenergic <span class="hlt">electron</span> <span class="hlt">fluxes</span> having energies up to 22 keV. Two principal concerns were the measuring of the charge distributions on dielectrics and the determining of causes of flashovers, events where dielectric surface charges abruptly transfer to the metallic structures. Surface charges are perturbed within 10 mm of interfaces. Perturbations are relatively small except within about 3 mm of the interface. The probability of flashover was found to be related to microscopic imperfections in the interfaces. As flashovers occur in an exposed metal substrate, points become burned into the dielectric along the slit. As these points develop, the probability of flashover increases greatly. An interface which is highly immune to flashover was formed by covering a dielectric film with a 1.5-mm-thick aperture plate which exposes the film through a machined opening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSH11B1664L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSH11B1664L"><span>STEREO SWEA Observations of Solar Wind Halo <span class="hlt">Electron</span> Anomalous Heat <span class="hlt">Fluxes</span> and their Organization by Solar Wind Structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luhmann, J. G.; Ellenburg, M. A.; Lee, C. O.; Schroeder, P. C.; Opitz, A.; Penou, E.; Lavraud, B.; Sauvaud, J. A.; Jian, L.; Russell, C. T.; Simunac, K. D.; Galvin, A. B.</p> <p>2010-12-01</p> <p>STEREO SWEA (Solar Wind <span class="hlt">Electron</span> Analyzer) provides the opportunity to observe solar wind halo <span class="hlt">electron</span> heat <span class="hlt">fluxes</span> and strahl over 4pi steradians at locations free of Earth bow shock contamination. We have analyzed these measurements together with the magnetic field and plasma parameters to determine their organization with solar wind stream structure during the period between early 2007 and late 2009. This period is characterized by a very low level of solar activity and thus presents an opportunity to diagnose the anomalous features, determining their location and character. This includes heat <span class="hlt">fluxes</span> that appear to be traveling back toward the Sun, possibly indicating folded interplanetary field lines, interplanetary field loops which may be part of ICMEs, or sources of suprathermal <span class="hlt">electrons</span> at shocks beyond 1 AU. Our results give a broad view of the issues related to using heat <span class="hlt">fluxes</span> to interpret interplanetary field topology, even with the benefit of 4pi observations and two spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NucFu..57b2010A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NucFu..57b2010A"><span>Fast measurements of the <span class="hlt">electron</span> temperature and parallel heat <span class="hlt">flux</span> in ELMy H-mode on the COMPASS tokamak</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adamek, J.; Seidl, J.; Komm, M.; Weinzettl, V.; Panek, R.; Stöckel, J.; Hron, M.; Hacek, P.; Imrisek, M.; Vondracek, P.; Horacek, J.; Devitre, A.; the COMPASS Team</p> <p>2017-02-01</p> <p>We report the latest results on fast measurements of the <span class="hlt">electron</span> temperature and parallel heat <span class="hlt">flux</span> in the COMPASS tokamak scrape-off layer (SOL) and divertor region during ELMy H-mode plasmas. The system of ball-pen and Langmuir probes installed on the divertor target, the horizontal reciprocating manipulator and the fast data-acquisition system with sampling frequency rate f  =  5 MSa s-1 allow us to measure the <span class="hlt">electron</span> temperature and parallel heat <span class="hlt">flux</span> during inter-ELM and ELM periods with high temporal resolution. The filamentary structure of the <span class="hlt">electron</span> temperature and parallel heat <span class="hlt">flux</span> was observed during ELMs in the SOL as well as in the divertor region. The position of the filaments within ELMs is not regular and therefore the resulting conditionally averaged ELM neglects the peak values of the <span class="hlt">electron</span> temperature and parallel heat <span class="hlt">flux</span>. We have found a substantial difference between the value of the radial power decay length in the inter-ELM period λ q,inter  =  2.5 mm and the decay length of the peak ELM heat <span class="hlt">flux</span> λ q,ELM  =  13.1 mm. The decay length of the ELM energy density was found to be λ E,ELM  =  5.4 mm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5114644','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5114644"><span>High <span class="hlt">flux</span> circularly polarized gamma beam factory: coupling a Fabry-Perot optical cavity with an <span class="hlt">electron</span> storage ring</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chaikovska, I.; Cassou, K.; Chiche, R.; Cizeron, R.; Cornebise, P.; Delerue, N.; Jehanno, D.; Labaye, F.; Marie, R.; Martens, A.; Peinaud, Y.; Soskov, V.; Variola, A.; Zomer, F.; Cormier, E.; Lhermite, J.; Dolique, V.; Flaminio, R.; Michel, C.; Pinard, L.; Sassolas, B.; Akagi, T.; Araki, S.; Honda, Y.; Omori, T.; Terunuma, N.; Urakawa, J.; Miyoshi, S.; Takahashi, T.; Yoshitama, H.</p> <p>2016-01-01</p> <p>We report and discuss high-<span class="hlt">flux</span> generation of circularly polarized γ-rays by means of Compton scattering. The γ-ray beam results from the collision of an external-cavity-enhanced infrared laser beam and a low emittance relativistic <span class="hlt">electron</span> beam. By operating a non-planar bow-tie high-finesse optical Fabry-Perot cavity coupled to a storage ring, we have recorded a <span class="hlt">flux</span> of up to (3.5 ± 0.3) × 108 photons per second with a mean measured energy of 24 MeV. The γ-ray <span class="hlt">flux</span> has been sustained for several hours. In particular, we were able to measure a record value of up to 400 γ-rays per collision in a full bandwidth. Moreover, the impact of Compton scattering on the <span class="hlt">electron</span> beam dynamics could be observed resulting in a reduction of the <span class="hlt">electron</span> beam lifetime correlated to the laser power stored in the Fabry-Perot cavity. We demonstrate that the <span class="hlt">electron</span> beam lifetime provides an independent and consistent determination of the γ-ray <span class="hlt">flux</span>. Furthermore, a reduction of the γ-ray <span class="hlt">flux</span> due to intrabeam scattering has clearly been identified. These results, obtained on an accelerator test facility, warrant potential scaling and revealed both expected and yet unobserved effects. They set the baseline for further scaling of the future Compton sources under development around the world. PMID:27857146</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27934925','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27934925"><span>Set anode potentials affect the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and microbial community structure in propionate-fed microbial electrolysis cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hari, Ananda Rao; Katuri, Krishna P; Logan, Bruce E; Saikaly, Pascal E</p> <p>2016-12-09</p> <p>Anode potential has been shown to be a critical factor in the rate of acetate removal in microbial electrolysis cells (MECs), but studies with fermentable substrates and set potentials are lacking. Here, we examined the impact of three different set anode potentials (SAPs; -0.25, 0, and 0.25 V vs. standard hydrogen electrode) on the electrochemical performance, <span class="hlt">electron</span> <span class="hlt">flux</span> to various sinks, and anodic microbial community structure in two-chambered MECs fed with propionate. Electrical current (49-71%) and CH4 (22.9-41%) were the largest <span class="hlt">electron</span> sinks regardless of the potentials tested. Among the three SAPs tested, 0 V showed the highest <span class="hlt">electron</span> <span class="hlt">flux</span> to electrical current (71 ± 5%) and the lowest <span class="hlt">flux</span> to CH4 (22.9 ± 1.2%). In contrast, the SAP of -0.25 V had the lowest <span class="hlt">electron</span> <span class="hlt">flux</span> to current (49 ± 6%) and the highest <span class="hlt">flux</span> to CH4 (41.1 ± 2%). The most dominant genera detected on the anode of all three SAPs based on 16S rRNA gene sequencing were Geobacter, Smithella and Syntrophobacter, but their relative abundance varied among the tested SAPs. Microbial community analysis implies that complete degradation of propionate in all the tested SAPs was facilitated by syntrophic interactions between fermenters and Geobacter at the anode and ferementers and hydrogenotrophic methanogens in suspension.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...636569C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...636569C"><span>High <span class="hlt">flux</span> circularly polarized gamma beam factory: coupling a Fabry-Perot optical cavity with an <span class="hlt">electron</span> storage ring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaikovska, I.; Cassou, K.; Chiche, R.; Cizeron, R.; Cornebise, P.; Delerue, N.; Jehanno, D.; Labaye, F.; Marie, R.; Martens, A.; Peinaud, Y.; Soskov, V.; Variola, A.; Zomer, F.; Cormier, E.; Lhermite, J.; Dolique, V.; Flaminio, R.; Michel, C.; Pinard, L.; Sassolas, B.; Akagi, T.; Araki, S.; Honda, Y.; Omori, T.; Terunuma, N.; Urakawa, J.; Miyoshi, S.; Takahashi, T.; Yoshitama, H.</p> <p>2016-11-01</p> <p>We report and discuss high-<span class="hlt">flux</span> generation of circularly polarized γ-rays by means of Compton scattering. The γ-ray beam results from the collision of an external-cavity-enhanced infrared laser beam and a low emittance relativistic <span class="hlt">electron</span> beam. By operating a non-planar bow-tie high-finesse optical Fabry-Perot cavity coupled to a storage ring, we have recorded a <span class="hlt">flux</span> of up to (3.5 ± 0.3) × 108 photons per second with a mean measured energy of 24 MeV. The γ-ray <span class="hlt">flux</span> has been sustained for several hours. In particular, we were able to measure a record value of up to 400 γ-rays per collision in a full bandwidth. Moreover, the impact of Compton scattering on the <span class="hlt">electron</span> beam dynamics could be observed resulting in a reduction of the <span class="hlt">electron</span> beam lifetime correlated to the laser power stored in the Fabry-Perot cavity. We demonstrate that the <span class="hlt">electron</span> beam lifetime provides an independent and consistent determination of the γ-ray <span class="hlt">flux</span>. Furthermore, a reduction of the γ-ray <span class="hlt">flux</span> due to intrabeam scattering has clearly been identified. These results, obtained on an accelerator test facility, warrant potential scaling and revealed both expected and yet unobserved effects. They set the baseline for further scaling of the future Compton sources under development around the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5146674','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5146674"><span>Set anode potentials affect the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and microbial community structure in propionate-fed microbial electrolysis cells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hari, Ananda Rao; Katuri, Krishna P.; Logan, Bruce E.; Saikaly, Pascal E.</p> <p>2016-01-01</p> <p>Anode potential has been shown to be a critical factor in the rate of acetate removal in microbial electrolysis cells (MECs), but studies with fermentable substrates and set potentials are lacking. Here, we examined the impact of three different set anode potentials (SAPs; −0.25, 0, and 0.25 V vs. standard hydrogen electrode) on the electrochemical performance, <span class="hlt">electron</span> <span class="hlt">flux</span> to various sinks, and anodic microbial community structure in two-chambered MECs fed with propionate. Electrical current (49–71%) and CH4 (22.9–41%) were the largest <span class="hlt">electron</span> sinks regardless of the potentials tested. Among the three SAPs tested, 0 V showed the highest <span class="hlt">electron</span> <span class="hlt">flux</span> to electrical current (71 ± 5%) and the lowest <span class="hlt">flux</span> to CH4 (22.9 ± 1.2%). In contrast, the SAP of −0.25 V had the lowest <span class="hlt">electron</span> <span class="hlt">flux</span> to current (49 ± 6%) and the highest <span class="hlt">flux</span> to CH4 (41.1 ± 2%). The most dominant genera detected on the anode of all three SAPs based on 16S rRNA gene sequencing were Geobacter, Smithella and Syntrophobacter, but their relative abundance varied among the tested SAPs. Microbial community analysis implies that complete degradation of propionate in all the tested SAPs was facilitated by syntrophic interactions between fermenters and Geobacter at the anode and ferementers and hydrogenotrophic methanogens in suspension. PMID:27934925</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPSCP...1a5030Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPSCP...1a5030Y"><span>Probability Density Functions of Floating Potential Fluctuations Due to Local <span class="hlt">Electron</span> <span class="hlt">Flux</span> Intermittency in a Linear ECR Plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshimura, Shinji; Terasaka, Kenichiro; Tanaka, Eiki; Aramaki, Mitsutoshi; Tanaka, Masayoshi Y.</p> <p></p> <p>An intermittent behavior of local <span class="hlt">electron</span> <span class="hlt">flux</span> in a laboratory ECR plasma is statistically analyzed by means of probability density functions (PDFs). The PDF constructed from a time series of the floating potential signal on a Langmuir probe has a fat tail in the negative value side, which reflects the intermittency of the local <span class="hlt">electron</span> <span class="hlt">flux</span>. The PDF of the waiting time, which is defined by the time interval between two successive events, is found to exhibit an exponential distribution, suggesting that the phenomenon is characterized by a stationary Poisson process. The underlying Poisson process is also confirmed by the number of events in given time intervals that is Poisson distributed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.1102H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.1102H"><span>Variability and spatial fine structure of precipitating and trapped medium-energy <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the noon sector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hargreaves, J. K.; Birch, M. J.; Evans, D. S.</p> <p>2014-02-01</p> <p>The relationships between the precipitating and trapped components of magnetospheric <span class="hlt">electron</span> <span class="hlt">flux</span> for energy ranges exceeding 30 and 100 keV have been investigated using data from polar orbiting satellites, the study being restricted to a limited geographic region at auroral latitudes in the noon sector. The <span class="hlt">electron</span> <span class="hlt">flux</span> of these energies is the cause of auroral radio absorption. The data are analyzed at two levels of detail. Variations between different passes are studied using their median values, and variations within passes are derived from individual data points at 2 s intervals, equivalent to about 10 km in distance. Several types of behavior are recognized. Basically, the ratio of precipitating to trapped <span class="hlt">flux</span> at energies exceeding 30 keV varies in proportion to the trapped <span class="hlt">flux</span>, though there is a limiting upper value where the two components are approximately equal. The precipitating <span class="hlt">flux</span> never exceeds the trapped <span class="hlt">flux</span> by any significant amount. These types appear to be consistent with weak and strong pitch angle scatterings, respectively. The precipitation at >100 keV varies somewhat with the >100 keV trapped <span class="hlt">flux</span> but more strongly with the >30 keV component, consistent with scattering by chorus waves produced by <span class="hlt">electrons</span> less energetic than those being scattered. Comparison between the two energy ranges shows that the precipitating component is always softer than the trapped. The detailed relationship between the precipitating and trapped components varies from pass to pass by an amount related to the east-west component of the interplanetary magnetic field. Superimposed on the above behavior are large reductions of precipitation, spatial rather than temporal in nature, during which the trapped <span class="hlt">flux</span> remains virtually unchanged. These reductions appear to be due to structures some tens of kilometers across, perhaps related to "ducts" within the magnetosphere. Some theoretical considerations based on the Kennel and Petscheck theory of scattering are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23947779','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23947779"><span>Carbon and <span class="hlt">electron</span> <span class="hlt">fluxes</span> during the electricity driven 1,3-propanediol biosynthesis from glycerol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Mi; Chen, Jingwen; Freguia, Stefano; Rabaey, Korneel; Keller, Jürg</p> <p>2013-10-01</p> <p>1,3-Propanediol (1,3-PDO) can be produced biologically through glycerol fermentation. While such a process typically involves a pure culture system, particularly for crude glycerol, there would be operational advantages if a mixed population could be used. However, in the latter case the yield is typically low. Here, we use electrical current as the driving force for a mixed population fermenting glycerol in the cathode of a microbial bioelectrochemical system (BES). The carbon and <span class="hlt">electron</span> flows were monitored by a titration and off-gas analysis (TOGA) sensor, and the syntrophic interactions in the BES were also investigated. Results show that on a carbon yield basis, current enhanced 1,3-PDO production from 24.8% (without current) to 50.1% (with a polarized biocathode at -0.9 V versus standard hydrogen electrode, SHE). <span class="hlt">Flux</span> analysis indicated that the reductive current can be integrated into glycerol metabolism to enhance 1,3-PDO yield and that glycerol metabolism was redirected from propionate fermentation to 1,3-PDO production. A polarization of -0.6 V (vs SHE) resulted in more fermentative hydrogen production (from 2.7% to 8.0% on <span class="hlt">electron</span> basis). 1,3-PDO production was also enhanced with hydrogen supply (37.7% on carbon basis), by suppressing hydrogen fermentation. Moreover, interspecies hydrogen transfer encouraged hydrogenotrophic methanogenesis, which was also accelerated by the cathodic polarization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSA33A1989G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSA33A1989G"><span>Predicting <span class="hlt">Electron</span> Energy <span class="hlt">Flux</span> Using Ground-Based Multi-Spectral Auroral Imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grubbs, G. A.; Samara, M.; Michell, R.; Redmon, R. J.</p> <p>2013-12-01</p> <p>High-resolution, multi-spectral auroral observations can now be routinely acquired using the Multi-spectral Observatory Of Sensitive EMCCDs (MOOSE), currently installed in Poker Flat, AK. Observations from the past 2 auroral seasons have yielded many simultaneous auroral observations in 4 different emission lines (427.8 nm, 557.7 nm, 630 nm, and 844.6 nm). From these data, the brightness of the absolute auroral emissions will be calculated. Combined with atmospheric modeling, auroral emission brightness will be used to predict the total energy <span class="hlt">flux</span> and characteristic energy of the <span class="hlt">electrons</span> responsible for the aurora. The theory behind this method is only developed for auroral measurements in the magnetic zenith, and therefore it is not known to what extent it can be applied off zenith. All-sky auroral image data will be examined and compared with DMSP satellite overpasses to quantify the extent to which the model can make predictions off-zenith, creating an empirical model that could then be applied to the many cases without overpasses. This will lead to large-scale 2-D maps of <span class="hlt">electron</span> precipitation characteristics which can contribute to global ionospheric models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM31A2437B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM31A2437B"><span>Statistical Study of <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts at GEO : occurrences, magnitudes, and main driving factors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boynton, R.; Mourenas, D.; Balikhin, M. A.</p> <p>2016-12-01</p> <p>Large decreases of <span class="hlt">electron</span> <span class="hlt">flux</span> were investigated for a range of energies, from 24.1 keV to 2.7 MeV. These dropouts are defined by a decrease of a factor of 4 in one day or a factor of 9 in two days, where each day has at least a factor of 2.5 decrease. These decrease were automatically identified. The statistics of these decreases were then studied. These statistics include the mean time between dropouts and the mean magnitude of each dropout. Also the Error Reduction ratio (ERR) analysis in the Forward Regression Orthogonal Least Squares (FROLS) algorithm was used to find a relationship of the energetic <span class="hlt">electron</span> depletion with the solar wind and geomagnetic indices. Different dropout occurrences and magnitudes were found in three distinct energy ranges, lower than 100 keV, 100-600 keV, and larger than 600 keV, corresponding to different groups of drivers and loss processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApPhL.111b1605S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhL.111b1605S"><span>Surfaces for <span class="hlt">high</span> <span class="hlt">heat</span> dissipation with no Leidenfrost limit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sajadi, Seyed Mohammad; Irajizad, Peyman; Kashyap, Varun; Farokhnia, Nazanin; Ghasemi, Hadi</p> <p>2017-07-01</p> <p>Heat dissipation from hot surfaces through cooling droplets is limited by the Leidenfrost point (LFP), in which an insulating vapor film prevents direct contact between the cooling droplet and the hot surface. A range of approaches have been developed to raise this limit to higher temperatures, but the limit still exists. Recently, a surface architecture, decoupled hierarchical structure, was developed that allows the suppression of LFP completely. However, heat dissipation by the structure in the low superheat region was inferior to other surfaces and the structure required an extensive micro/nano fabrication procedure. Here, we present a metallic surface structure with no LFP and <span class="hlt">high</span> <span class="hlt">heat</span> dissipation capacity in all temperature ranges. The surface features the nucleate boiling phenomenon independent of the temperature with an approximate heat transfer coefficient of 20 kW m-2 K-1. This surface is developed in a one-step process with no micro/nano fabrication. We envision that this metallic surface provides a unique platform for <span class="hlt">high</span> <span class="hlt">heat</span> dissipation in power generation, photonics/<span class="hlt">electronics</span>, and aviation systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22570237','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22570237"><span>A <span class="hlt">flux</span>-splitting method for hyperbolic-equation system of magnetized <span class="hlt">electron</span> fluids in quasi-neutral plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kawashima, Rei Komurasaki, Kimiya Schönherr, Tony</p> <p>2016-04-01</p> <p>A <span class="hlt">flux</span>-splitting method is proposed for the hyperbolic-equation system (HES) of magnetized <span class="hlt">electron</span> fluids in quasi-neutral plasmas. The numerical <span class="hlt">fluxes</span> are split into four categories, which are computed by using an upwind method which incorporates a <span class="hlt">flux</span>-vector splitting (FVS) and advection upstream splitting method (AUSM). The method is applied to a test calculation condition of uniformly distributed and angled magnetic lines of force. All of the pseudo-time advancement terms converge monotonically and the conservation laws are strictly satisfied in the steady state. The calculation results are compared with those computed by using the elliptic–parabolic-equation system (EPES) approach using a magnetic-field-aligned mesh (MFAM). Both qualitative and quantitative comparisons yield good agreements of results, indicating that the HES approach with the <span class="hlt">flux</span>-splitting method attains a high computational accuracy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.1789D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.1789D"><span>On the origin of low-energy <span class="hlt">electrons</span> in the inner magnetosphere: <span class="hlt">Fluxes</span> and pitch-angle distributions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, M. H.; Reeves, G. D.; Larsen, B. A.; Friedel, R. F. W.; Thomsen, M. F.; Fernandes, P. A.; Skoug, R. M.; Funsten, H. O.; Sarno-Smith, L. K.</p> <p>2017-02-01</p> <p>Accurate knowledge of the plasma <span class="hlt">fluxes</span> in the inner magnetosphere is essential for both scientific and programmatic applications. Knowledge of the low-energy <span class="hlt">electrons</span> (approximately tens to hundreds of eV) in the inner magnetosphere is particularly important since these <span class="hlt">electrons</span> are acted upon by various physical processes, accelerating the <span class="hlt">electrons</span> to higher energies, and also causing their loss. However, measurements of low-energy <span class="hlt">electrons</span> are challenging, and as a result, this population has been somewhat neglected previously. This study concerns observations of low-energy <span class="hlt">electrons</span> made by the Helium Oxygen Proton <span class="hlt">Electron</span> instrument on board the Van Allen Probes satellites and also observations from geosynchronous orbit made by the Magnetospheric Plasma Analyzer on board Los Alamos National Laboratory satellites. The <span class="hlt">fluxes</span> of <span class="hlt">electrons</span> from 30 eV to 1 keV are quantified as a function of pitch-angle, McIlwain L parameter, and local time for both quiet and active periods. Results indicate two sources for low-energy <span class="hlt">electrons</span> in this energy range: the low-energy tail of the <span class="hlt">electron</span> plasma sheet and the high-energy tail of the dayside ionosphere. These populations are identified primarily as a result of their different pitch-angle distributions. Field-aligned outflows from the dayside ionosphere are observed at all L shells during quiet and active periods. Our results also demonstrate that the dayside <span class="hlt">electron</span> field-aligned <span class="hlt">fluxes</span> at 30 eV are particularly strong between L values of 6 and 7, indicating an enhanced source within the polar ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26799383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26799383"><span>Concerted <span class="hlt">Electronic</span> and Nuclear <span class="hlt">Fluxes</span> During Coherent Tunnelling in Asymmetric Double-Well Potentials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bredtmann, Timm; Manz, Jörn; Zhao, Jian-Ming</p> <p>2016-05-19</p> <p>The quantum theory of concerted <span class="hlt">electronic</span> and nuclear <span class="hlt">fluxes</span> (CENFs) during coherent periodic tunnelling from reactants (R) to products (P) and back to R in molecules with asymmetric double-well potentials is developed. The results are deduced from the solution of the time-dependent Schrödinger equation as a coherent superposition of two eigenstates; here, these are the two states of the lowest tunnelling doublet. This allows the periodic time evolutions of the resulting <span class="hlt">electronic</span> and nuclear probability densities (EPDs and NPDs) as well as the CENFs to be expressed in terms of simple sinusodial functions. These analytical results reveal various phenomena during coherent tunnelling in asymmetric double-well potentials, e.g., all EPDs and NPDs as well as all CENFs are synchronous. Distortion of the symmetric reference to a system with an asymmetric double-well potential breaks the spatial symmetry of the EPDs and NPDs, but, surprisingly, the symmetry of the CENFs is conserved. Exemplary application to the Cope rearrangement of semibullvalene shows that tunnelling of the ideal symmetric system can be suppressed by asymmetries induced by rather small external electric fields. The amplitude for the half tunnelling, half nontunnelling border is as low as 0.218 × 10(-8) V/cm. At the same time, the delocalized eigenstates of the symmetric reference, which can be regarded as Schrödinger's cat-type states representing R and P with equal probabilities, get localized at one or the other minima of the asymmetric double-well potential, representing either R or P.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhyC..455...19B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhyC..455...19B"><span><span class="hlt">Flux</span> pinning by Al-based nanoparticles embedded in YBCO: A transmission <span class="hlt">electron</span> microscopic study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ben Azzouz, F.; Zouaoui, M.; Mellekh, A.; Annabi, M.; Van Tendeloo, G.; Ben Salem, M.</p> <p>2007-05-01</p> <p>A series of YBa2Cu3Oy (YBCO) samples with small amounts (0-0.6 wt.%) of nanosized alumina particles (50 nm) are synthesized in air by solid state reaction. The microstructure has been characterized by transmission <span class="hlt">electron</span> microscopy (TEM) and the critical current density Jc has been measured by the standard four-probe method in the applied magnetic field at 77 K. TEM and energy dispersive X-ray spectroscopy (EDS) analysis have shown that alumina reacts with the YBCO matrix to form nanometric aluminium-rich inhomogeneities intergrown within the YBCO superconducting matrix. These inhomogeneities reduce the onset transition temperature Tconset and the zero resistance temperature Tc. In spite of the monotonic decrease of the superconducting temperature Tc with increasing alumina addition, the Jc(H) behaviour is remarkably improved. The characteristic behaviour of Jc can be explained in terms of the counterbalance of two effects simultaneously caused by the nanometric alumina addition in the system. One effect is the formation of the Al-rich nanometric inhomogeneities relevant for the <span class="hlt">flux</span> pinning, and the other effect is the reduction of matrix superconducting volume, which is reflected by a decrease of the critical current density Jc at zero applied magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992NucFu..32.1755M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992NucFu..32.1755M"><span>Heat <span class="hlt">flux</span> of fast <span class="hlt">electrons</span> to the limiter in lower hybrid current drive plasma on WT-3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maekawa, T.; Nakamura, M.; Komatsu, T.; Kishino, T.; Kishigami, Y.; Makino, K.; Maehara, T.; Minami, T.; Hanada, K.; Iida, M.; Terumichi, Y.; Tanaka, S.</p> <p>1992-10-01</p> <p>The heat <span class="hlt">flux</span> of fast <span class="hlt">electrons</span> to the local limiter in LHCD plasmas in WT-3 has been investigated by thermal measurement of the limiter. The amount of the heat <span class="hlt">flux</span> (PFE) is found to be about on third of the net radiofrequency power (Prf) injected into the plasma for various discharge conditions. The results combined with other measurements show that the confinement of fast <span class="hlt">electrons</span> deteriorates as Prf increases. This direct loss of fast <span class="hlt">electrons</span> is one of the causes of the degradation of the current drive efficiency. Heat transport of the bulk <span class="hlt">electrons</span> is also found to increase as Prf increases. Experimental results indicate that a significant part of the remaining RF power (2Prf/3) flows to the bulk <span class="hlt">electrons</span>. The slowing down power of fast <span class="hlt">electrons</span> in the energy range above several tens of keV is estimated to be quite small compared with 2Prf/3, suggesting that a significant part of the remaining power flows to the bulk <span class="hlt">electrons</span> via other channels. A plausible channel is the absorption of RF power via lower energy <span class="hlt">electrons</span> by an upshift of the parallel refractive index of the injected lower hybrid waves. This seems to be another cause of the degradation of the current drive efficiency</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840030076&hterms=ghost&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dghost','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840030076&hterms=ghost&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dghost"><span>The Mimas ghost revisited - An analysis of the <span class="hlt">electron</span> <span class="hlt">flux</span> and <span class="hlt">electron</span> microsignatures observed in the vicinity of Mimas at Saturn</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chenette, D. L.; Stone, E. C.</p> <p>1983-01-01</p> <p>An analysis of the <span class="hlt">electron</span>-absorption signature observed by the cosmic-ray system on Voyager 2 near the orbit of Mimas is presented. It is found that these observations cannot be explained as the absorption signature of Mimas. By combining Pioneer 11 and Voyager 2 measurements of the <span class="hlt">electron</span> <span class="hlt">flux</span> at Mimas's orbit (L = 3.1), an <span class="hlt">electron</span> spectrum is found in which most of the <span class="hlt">flux</span> above about 100 keV is concentrated near 1 to 3 MeV. This spectral form is qualitatively consistent with the bandpass filter model of Van Allen et al. (1980). The expected Mimas absorption signature is calculated from this spectrum neglecting radial diffusion. Since no Mimas absorption signature was observed in the inbound Voyager 2 data, a lower limit on the diffusion coefficient for MeV <span class="hlt">electrons</span> at L = 3.1 of D greater than 10 to the -8th sq Saturn radii/sec is obtained. With a diffusion coefficient this large, both the Voyager 2 and the Pioneer 11 small-scale <span class="hlt">electron</span>-absorption-signature observations in Mimas's orbit are enigmatic. Thus the mechanism for producing these signatures is referred to as the Mimas ghost. A cloud of material in orbit with Mimas may account for the observed <span class="hlt">electron</span> signature if the cloud is at least 1-percent opaque to <span class="hlt">electrons</span> across a region extending over a few hundred kilometers.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840030076&hterms=Ghost&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DGhost','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840030076&hterms=Ghost&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DGhost"><span>The Mimas ghost revisited - An analysis of the <span class="hlt">electron</span> <span class="hlt">flux</span> and <span class="hlt">electron</span> microsignatures observed in the vicinity of Mimas at Saturn</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chenette, D. L.; Stone, E. C.</p> <p>1983-01-01</p> <p>An analysis of the <span class="hlt">electron</span>-absorption signature observed by the cosmic-ray system on Voyager 2 near the orbit of Mimas is presented. It is found that these observations cannot be explained as the absorption signature of Mimas. By combining Pioneer 11 and Voyager 2 measurements of the <span class="hlt">electron</span> <span class="hlt">flux</span> at Mimas's orbit (L = 3.1), an <span class="hlt">electron</span> spectrum is found in which most of the <span class="hlt">flux</span> above about 100 keV is concentrated near 1 to 3 MeV. This spectral form is qualitatively consistent with the bandpass filter model of Van Allen et al. (1980). The expected Mimas absorption signature is calculated from this spectrum neglecting radial diffusion. Since no Mimas absorption signature was observed in the inbound Voyager 2 data, a lower limit on the diffusion coefficient for MeV <span class="hlt">electrons</span> at L = 3.1 of D greater than 10 to the -8th sq Saturn radii/sec is obtained. With a diffusion coefficient this large, both the Voyager 2 and the Pioneer 11 small-scale <span class="hlt">electron</span>-absorption-signature observations in Mimas's orbit are enigmatic. Thus the mechanism for producing these signatures is referred to as the Mimas ghost. A cloud of material in orbit with Mimas may account for the observed <span class="hlt">electron</span> signature if the cloud is at least 1-percent opaque to <span class="hlt">electrons</span> across a region extending over a few hundred kilometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004988','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004988"><span>The Mimas ghost revisited: An analysis of the <span class="hlt">electron</span> <span class="hlt">flux</span> and <span class="hlt">electron</span> microsignatures observed in the vicinity of Mimas at Saturn</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chenette, D. L.; Stone, E. C.</p> <p>1983-01-01</p> <p>An analysis of the <span class="hlt">electron</span> absorption signature observed by the Cosmic Ray System (CRS) on Voyage 2 near the orbit of Mimas is presented. We find that these observations cannot be explained as the absorption signature of Mimas. Combing Pioneer 11 and Voyager 2 measurements of the <span class="hlt">electron</span> <span class="hlt">flux</span> at Mimas's orbit (L=3.1), we find an <span class="hlt">electron</span> spectrum where most of the <span class="hlt">flux</span> above approx 100 keV is concentrated near 1 to 3 MeV. The expected Mimas absorption signature is calculated from this spectrum neglecting radial diffusion. A lower limit on the diffusion coefficient for MeV <span class="hlt">electrons</span> is obtained. With a diffusion coefficient this large, both the Voyager 2 and the Pioneer 11 small-scale <span class="hlt">electron</span> absorption signature observations in Mimas's orbit are enigmatic. Thus we refer to the mechanism for producing these signatures as the Mimas ghost. A cloud of material in orbit with Mimas may account for the observed <span class="hlt">electron</span> signature if the cloud is at least 1% opaque to <span class="hlt">electrons</span> across a region extending over a few hundred kilometers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991sctip.........P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991sctip.........P"><span>Magnetic topology of coronal mass ejections based on ISEE-3 observations of bidirectional <span class="hlt">electron</span> <span class="hlt">fluxes</span> at 1 AU</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, J. L.; Gosling, J. T.; McComas, D. J.; Bame, S. J.; Feldman, W. C.</p> <p></p> <p>The solar wind <span class="hlt">electron</span> heat <span class="hlt">flux</span> is carried primarily by superthermal halo <span class="hlt">electrons</span> with energies at 1 AU of approximately 80 eV and greater. These halo <span class="hlt">electrons</span> typically are beamed antisunward along the IMF, indicating effective magnetic connection to the Sun only in one direction. However, ISEE-3 <span class="hlt">electron</span> observations at 1 AU show that counterstreaming halo beams, suggesting closed magnetic structures, prevail within CMEs. These structures might be magnetic tongues, tied to the Sun at both ends, magnetically detached plasmoids, or perhaps complex <span class="hlt">flux</span> rope structures. We present the results of analysis of ISEE-3 <span class="hlt">electron</span> observations within 39 CME's. Parameters analyzed include: the asymmetry between the counterstreaming beams, control by the IMF orientation, and the variation of the <span class="hlt">electron</span> distributions as a particular CME convects past the spacecraft. We find that some CME's contain nearly symmetric <span class="hlt">electron</span> beams, while others are strongly asymmetric, and that beam propagating most nearly antisunward is generally dominant. The more nearly radial the IMF the greater is the symmetry between outward and inward beams. Trends observed as CME's propagate past the spacecraft probably result primarily from the compression of the leading edge. We present examples of a previously unreported strahl-on-strahl distribution, suggesting continued magnetic connection to the corona, in which a narrow antisunward beam is superimposed on a broader beam. Preliminary results show that such spectra are present in a substantial fraction of the observed CME's. Taken as a whole, our results appear to favor a tongue or <span class="hlt">flux</span> rope scenario rather than a detached plasmoid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005IJMPB..19.3483A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005IJMPB..19.3483A"><span>Effects of the Magnetic <span class="hlt">Flux</span> and of the <span class="hlt">Electron</span> Momentum on the Transmission Amplitude in the Aharonov-Bohm Interferometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amaresh Kumar, M. V.; Sahoo, Debendranath</p> <p></p> <p>A characterization of the two-terminal open-ring Aharonov-Bohm interferometer is made by analyzing the phase space plots in the complex transmission amplitude plane. Two types of plots are considered: type 1 plot uses the magnetic <span class="hlt">flux</span> as the variable parameter and type 2 plot which uses the <span class="hlt">electron</span> momentum as the variable parameter. In type 1 plot, the trajectory closes upon itself only when the ratio R of the arm lengths (of the interferometer) is a rational fraction, and the shape and the type of the generated flower-like pattern is sensitive to the <span class="hlt">electron</span> momentum. For momenta corresponding to discrete eigenstates of the perfect ring (i.e., the ring without the leads), the trajectory passes through the origin a certain fixed number of times before closing upon itself, whereas for arbitrary momenta it never passes through the origin. Although the transmission coefficient is periodic in the <span class="hlt">flux</span> with the elementary <span class="hlt">flux</span> quantum as the basic period, the phenomenon of <span class="hlt">electron</span> transmission is shown not to be so when analyzed via the present technique. The periodicity is seen to spread over several <span class="hlt">flux</span> units whenever R is a rational fraction whereas there is absolutely no periodicity present when R is an irrational number. In type 2 plot, closed trajectories passing through the origin a number of times are seen for R being a rational fraction. The case R = 1 (i.e., a symmetric ring) with zero <span class="hlt">flux</span> is rather pathological — it presents a closed loop surrounding the origin. For irrational R values, the trajectories never close.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4485056','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4485056"><span><span class="hlt">Flux</span> balance analysis reveals acetate metabolism modulates cyclic <span class="hlt">electron</span> flow and alternative glycolytic pathways in Chlamydomonas reinhardtii</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chapman, Stephen P.; Paget, Caroline M.; Johnson, Giles N.; Schwartz, Jean-Marc</p> <p>2015-01-01</p> <p>Cells of the green alga Chlamydomonas reinhardtii cultured in the presence of acetate perform mixotrophic growth, involving both photosynthesis and organic carbon assimilation. Under such conditions, cells exhibit a reduced capacity for photosynthesis but a higher growth rate, compared to phototrophic cultures. Better understanding of the down regulation of photosynthesis would enable more efficient conversion of carbon into valuable products like biofuels. In this study, <span class="hlt">Flux</span> Balance Analysis (FBA) and <span class="hlt">Flux</span> Variability Analysis (FVA) have been used with a genome scale model of C. reinhardtii to examine changes in intracellular <span class="hlt">flux</span> distribution in order to explain their changing physiology. Additionally, a reaction essentiality analysis was performed to identify which reaction subsets are essential for a given growth condition. Our results suggest that exogenous acetate feeds into a modified tricarboxylic acid (TCA) cycle, which bypasses the CO2 evolution steps, explaining increases in biomass, consistent with experimental data. In addition, reactions of the oxidative pentose phosphate and glycolysis pathways, inactive under phototrophic conditions, show substantial <span class="hlt">flux</span> under mixotrophic conditions. Importantly, acetate addition leads to an increased <span class="hlt">flux</span> through cyclic <span class="hlt">electron</span> flow (CEF), but results in a repression of CO2 fixation via Rubisco, explaining the down regulation of photosynthesis. However, although CEF enhances growth on acetate, it is not essential—impairment of CEF results in alternative metabolic pathways being increased. We have demonstrated how the reactions of photosynthesis interconnect with carbon metabolism on a global scale, and how systems approaches play a viable tool in understanding complex relationships at the scale of the organism. PMID:26175742</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26175742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26175742"><span><span class="hlt">Flux</span> balance analysis reveals acetate metabolism modulates cyclic <span class="hlt">electron</span> flow and alternative glycolytic pathways in Chlamydomonas reinhardtii.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chapman, Stephen P; Paget, Caroline M; Johnson, Giles N; Schwartz, Jean-Marc</p> <p>2015-01-01</p> <p>Cells of the green alga Chlamydomonas reinhardtii cultured in the presence of acetate perform mixotrophic growth, involving both photosynthesis and organic carbon assimilation. Under such conditions, cells exhibit a reduced capacity for photosynthesis but a higher growth rate, compared to phototrophic cultures. Better understanding of the down regulation of photosynthesis would enable more efficient conversion of carbon into valuable products like biofuels. In this study, <span class="hlt">Flux</span> Balance Analysis (FBA) and <span class="hlt">Flux</span> Variability Analysis (FVA) have been used with a genome scale model of C. reinhardtii to examine changes in intracellular <span class="hlt">flux</span> distribution in order to explain their changing physiology. Additionally, a reaction essentiality analysis was performed to identify which reaction subsets are essential for a given growth condition. Our results suggest that exogenous acetate feeds into a modified tricarboxylic acid (TCA) cycle, which bypasses the CO2 evolution steps, explaining increases in biomass, consistent with experimental data. In addition, reactions of the oxidative pentose phosphate and glycolysis pathways, inactive under phototrophic conditions, show substantial <span class="hlt">flux</span> under mixotrophic conditions. Importantly, acetate addition leads to an increased <span class="hlt">flux</span> through cyclic <span class="hlt">electron</span> flow (CEF), but results in a repression of CO2 fixation via Rubisco, explaining the down regulation of photosynthesis. However, although CEF enhances growth on acetate, it is not essential-impairment of CEF results in alternative metabolic pathways being increased. We have demonstrated how the reactions of photosynthesis interconnect with carbon metabolism on a global scale, and how systems approaches play a viable tool in understanding complex relationships at the scale of the organism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850044805&hterms=energy+comparison&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Denergy%2Bcomparison','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850044805&hterms=energy+comparison&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Denergy%2Bcomparison"><span>A comparison of precipitating <span class="hlt">electron</span> energy <span class="hlt">flux</span> on March 22, 1979 with an empirical model - CDAW 6</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Simons, S. L., Jr.; Reiff, P. H.; Spiro, R. W.; Hardy, D. A.; Kroehl, H. W.</p> <p>1985-01-01</p> <p>Data recorded by Defense Meteorological Satellite Program, Tiros and P-78-1 satellites for the CDAW 6 event on March 22, 1979, have been compared with a statistical model of precipitating <span class="hlt">electron</span> <span class="hlt">fluxes</span>. Comparisons have been made on both an orbit-by-orbit basis and on a global basis by sorting and binning the data by AE index, invariant latitude, and magnetic local time in a manner similar to which the model was generated. It is concluded that the model <span class="hlt">flux</span> agrees with the data to within a factor of two, although small features and the exact locations of features are not consistently reproduced. In addition, the latitude of highest <span class="hlt">electron</span> precipitation usually occurs about 3 deg more poleward in the model than in the data. This discrepancy is attributed to ring current inflation of the storm time magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21420907','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21420907"><span>Ground-based observations of thunderstorm-correlated <span class="hlt">fluxes</span> of high-energy <span class="hlt">electrons</span>, gamma rays, and neutrons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chilingarian, A.; Daryan, A.; Arakelyan, K.; Hovhannisyan, A.; Mailyan, B.; Melkumyan, L.; Hovsepyan, G.; Chilingaryan, S.; Reymers, A.; Vanyan, L.</p> <p>2010-08-15</p> <p>The Aragats Space Environmental Center facilities continuously measure <span class="hlt">fluxes</span> of neutral and charged secondary cosmic ray incidents on the Earth's surface. Since 2003 in the 1-minute time series we have detected more than 100 enhancements in the <span class="hlt">electron</span>, gamma ray, and neutron <span class="hlt">fluxes</span> correlated with thunderstorm activities. During the periods of the count rate enhancements, lasting tens of minutes, millions of additional particles were detected. Based on the largest particle event of September 19, 2009, we show that our measurements support the existence of long-lasting particle multiplication and acceleration mechanisms in the thunderstorm atmosphere. For the first time we present the energy spectra of <span class="hlt">electrons</span> and gamma rays from the particle avalanches produced in the thunderstorm atmosphere, reaching the Earth's surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6712688','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6712688"><span>Spin <span class="hlt">flux</span> and magnetic solitons in an interacting two-dimensional <span class="hlt">electron</span> gas: Topology of two-valued wave functions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>John, S.; Golubentsev, A. )</p> <p>1995-01-01</p> <p>For a topological antiferromagnet on a square lattice, with the standard Hartree-Fock, spin-density-wave decoupling of the on-site Hubbard interaction, there is an exact mapping of the low-energy one-<span class="hlt">electron</span> excitation spectrum to a relativistic Dirac continuum field theory. In this field theory, the Dirac mass gap is precisely the Mott-Hubbard charge gap and the continuum field variable is an eight-component Dirac spinor describing the components of physical <span class="hlt">electron</span>-spin amplitude on each of the four sites of the elementary plaquette in the original Hubbard model. Within this continuum model we derive explicitly the existence of hedgehog Skyrmion textures as local minima of the classical magnetic energy. These magnetic solitons carry a topological winding number [mu] associated with the vortex rotation of the background magnetic moment field by a phase angle 2[pi][mu] along a path encircling the soliton. Such solitons also carry a spin <span class="hlt">flux</span> of [mu][pi] through the plaquette on which they are centered. The [mu]=1 hedgehog Skyrmion describes a local transition from the topological (antiperiodic) sector of the one-<span class="hlt">electron</span> Hilbert space to the nontopological sector. We derive from first principles the existence of deep level localized <span class="hlt">electronic</span> states within the Mott-Hubbard charge gap for the [mu]=1 and 2 solitons. The spectrum of localized states is symmetric about [ital E]=0 and each subgap <span class="hlt">electronic</span> level can be occupied by a pair of <span class="hlt">electrons</span> in which one <span class="hlt">electron</span> resides primarily on one sublattice and the second <span class="hlt">electron</span> on the other sublattice. It is suggested that <span class="hlt">flux</span>-carrying solitons and the subgap <span class="hlt">electronic</span> structure which they induce are important in understanding the physical behavior of doped Mott insulators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPNI3001H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPNI3001H"><span>The Role of ITG/TEM/ETG Cross-Scale Coupling in Explaining Experimental <span class="hlt">Electron</span> Heat <span class="hlt">Flux</span> and Profile Stiffness</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howard, N. T.</p> <p>2015-11-01</p> <p>Anomalous <span class="hlt">electron</span> thermal transport in tokamak plasmas is the ``great unsolved problem of tokamak transport physics'' [Batchelor Plasma Sci. Tec. 2007]. For years it has been speculated that short wavelength ETG turbulence plays a key role, but simulation capturing both ion and <span class="hlt">electron</span>-scale turbulence simultaneously had never been tested quantitatively against experiment due to extreme computational requirements. Only recently have gyrokinetic codes and supercomputing resources together been able to capture the physics of cross-scale coupling between long wavelength ITG/TEM and short wavelength ETG turbulence. In C-Mod, long wavelength simulations often under-predict <span class="hlt">electron</span> heat <span class="hlt">flux</span>. As a result, dedicated experiments have been performed in L-mode plasmas to validate multi-scale nonlinear gyrokinetic simulations. In this talk, the first set of full-physics, multi-scale simulations of a tokamak plasma performed with the GYRO code are compared to experiment. The simulations include coupled ITG/TEM/ETG turbulence (kθρs < 48 . 0) at realistic mass ratio (mi/me = 3600), with experimental inputs for impurities, geometry, ExB shear, and collisions. 100M CPU hours were required for six simulations to scan the ITG and ETG drive terms (a/LTi and a/LTe) within experimental error bars. The multi-scale simulations show for the first time that ETG streamers coexist and nonlinearly couple with ITG and zonal flows. This nonlinear cross-scale coupling enhances both ion and <span class="hlt">electron</span> heat <span class="hlt">fluxes</span> by up to a factor of 10 above standard, long wavelength simulation, resulting in simulations that simultaneously match experimental ion and <span class="hlt">electron</span> heat <span class="hlt">fluxes</span> and <span class="hlt">electron</span> profile stiffness. The new physics of ITG/ETG/zonal flow coupling has important implications for predictions of ITER performance and may be linked to phenomena such as confinement transitions and rotation reversals. This work was supported by DOE contract - DE-FC02-99ER54512-CMOD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JEMat..44.1116V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JEMat..44.1116V"><span>Solder <span class="hlt">Flux</span> Residues and Humidity-Related Failures in <span class="hlt">Electronics</span>: Relative Effects of Weak Organic Acids Used in No-Clean <span class="hlt">Flux</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan</p> <p>2015-04-01</p> <p>This paper presents the results of humidity testing of weak organic acids (WOAs), namely adipic, succinic, glutaric, dl-malic, and palmitic acids, which are commonly used as activators in no-clean solder <span class="hlt">fluxes</span>. The study was performed under humidity conditions varying from 60% relative humidity (RH) to ˜99%RH at 25°C. The following parameters were used for characterization of WOAs: mass gain due to water adsorption and deliquescence of the WOA (by quartz crystal microbalance), resistivity of the water layer formed on the printed circuit board (by impedance spectroscopy), and leakage current measured using the surface insulation resistance pattern in the potential range from 0 V to 10 V. The combined results indicate the importance of the WOA chemical structure for the water adsorption and therefore conductive water layer formation on the printed circuit board assembly (PCBA). A substantial increase of leakage currents and probability of electrochemical migration was observed at humidity levels above the RH corresponding to the deliquescence point of WOAs present as contaminants on the printed circuit boards. The results suggest that use of solder <span class="hlt">fluxes</span> with WOAs having higher deliquescence point could improve the reliability of <span class="hlt">electronics</span> operating under circumstances in which exposure to high humidity is likely to occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981seus.proc..189P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981seus.proc..189P"><span><span class="hlt">Electron</span> content modeling - The significance of protonospheric contents and apparent <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poulter, E. M.; Hargreaves, J. K.; Bailey, G. J.; Moffett, R. J.</p> <p></p> <p>A time-dependent model of the plasmasphere and the separation of TEC obtained from group delay measurements are studied. Temporal variations of the protonospheric content are interpreted as equivalent <span class="hlt">fluxes</span>, and the physical validity of the deduced quantities are investigated using a generalized model in which integration of the time dependent continuity and momentum equations along selected L-shells yields the ion densities and <span class="hlt">fluxes</span>. The shape parameters simulated by the equinox model agree by day, although night model values show discrepancies. Residual content is interpreted as the slant H(+) content beyond 2500 km, with the validity depending on the location of the receiving station and the state of the plasmasphere. The rate of change of residual content may be interpreted as a proton <span class="hlt">flux</span>, although the method is not valid for sudden perturbations, and the recovery of Np approaches that for <span class="hlt">flux</span> tubes with L values slightly greater than the minimum crossed for the three ray paths considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1786m0002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1786m0002S"><span>Crossed contributions to <span class="hlt">electron</span> and heavy-particle transport <span class="hlt">fluxes</span> for magnetized plasmas in the continuum regime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scoggins, James B.; Knisely, Carleton P.; Magin, Thierry E.</p> <p>2016-11-01</p> <p>We propose a unified fluid model for multicomponent plasmas in thermal nonequilibrium accounting for the influence of the electromagnetic field. In a previous work, this model was derived from kinetic theory based on a generalized Chapman-Enskog perturbative solution of the Boltzmann equation, scaled using the ratio of <span class="hlt">electron</span> to heavy-particle masses. Anisotropic transport properties were derived in terms of bracket integrals. In this work, explicit expressions for asymptotic solutions of the transport properties are derived using a spectral Galerkin projection supplied with Laguerre-Sonine polynomial basis functions, and we analyze the crossed contributions to <span class="hlt">electron</span> and heavy particle mass and energy <span class="hlt">fluxes</span>, known as the Kolesnikov effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA102905','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA102905"><span>Approximate Analytic Solutions for the Primary Auroral <span class="hlt">Electron</span> <span class="hlt">Flux</span> and Related Quantities.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1981-03-03</p> <p>Preliminary Remarks 18 8.2 Unidirectional- Monoenergetic Incident <span class="hlt">Flux</span> 19 8.3 Isotropic-Maxwellian Incident <span class="hlt">Flux</span> 20 8.4 Isotropic- Monoenergetic Incident...PSEUDOPARTICLES To APPROXIMATE THE SUMS 25 51 Contents 11. COMPARISONS 28 11. 1 Preliminary Remarks 28 11. 2 Comparisons for Isotropic - Monoenerget ie...the Analytic, Range, and Rees Models for 10, 5, and 2 KeV Isotrqpic- Monoenergetic Sources Each Containing 1 erg/cm s 30 6. Incident Maxwellian Energy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22436618','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22436618"><span>The mechanism of chemisorption of hydrogen atom on graphene: Insights from the reaction force and reaction <span class="hlt">electronic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cortés-Arriagada, Diego Gutiérrez-Oliva, Soledad; Herrera, Bárbara; Soto, Karla; Toro-Labbé, Alejandro</p> <p>2014-10-07</p> <p>At the PBE-D3/cc-pVDZ level of theory, the hydrogen chemisorption on graphene was analyzed using the reaction force and reaction <span class="hlt">electronic</span> <span class="hlt">flux</span> (REF) theories in combination with <span class="hlt">electron</span> population analysis. It was found that chemisorption energy barrier is mainly dominated by structural work (∼73%) associated to the substrate reconstruction whereas the <span class="hlt">electronic</span> work is the greatest contribution of the reverse energy barrier (∼67%) in the desorption process. Moreover, REF shows that hydrogen chemisorption is driven by charge transfer processes through four <span class="hlt">electronic</span> events taking place as H approaches the adsorbent surface: (a) intramolecular charge transfer in the adsorbent surface; (b) surface reconstruction; (c) substrate magnetization and adsorbent carbon atom develops a sp{sup 3} hybridization to form the σC-H bond; and (d) spontaneous intermolecular charge transfer to reach the final chemisorbed state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22272982','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22272982"><span>The contribution of Fermi gamma-ray pulsars to the local <span class="hlt">flux</span> of cosmic-ray <span class="hlt">electrons</span> and positrons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gendelev, Leo; Profumo, Stefano; Dormody, Michael E-mail: profumo@scipp.ucsc.edu</p> <p>2010-02-01</p> <p>We analyze the contribution of gamma-ray pulsars from the first Fermi-Large Area Telescope (LAT) catalogue to the local <span class="hlt">flux</span> of cosmic-ray <span class="hlt">electrons</span> and positrons (e{sup +}e{sup −}). We present new distance estimates for all Fermi gamma-ray pulsars, based on the measured gamma-ray <span class="hlt">flux</span> and pulse shape. We then estimate the contribution of gamma-ray pulsars to the local e{sup +}e{sup −} <span class="hlt">flux</span>, in the context of a simple model for the pulsar e{sup +}e{sup −} emission. We find that 10 of the Fermi pulsars potentially contribute significantly to the measured e{sup +}e{sup −} <span class="hlt">flux</span> in the energy range between 100 GeV and 1 TeV. Of the 10 pulsars, 2 are old EGRET gamma-ray pulsars, 2 pulsars were discovered with radio ephemerides, and 6 were discovered with the Fermi pulsar blind-search campaign. We argue that known radio pulsars fall in regions of parameter space where the e{sup +}e{sup −} contribution is predicted to be typically much smaller than from those regions where Fermi-LAT pulsars exist. However, comparing the Fermi gamma-ray <span class="hlt">flux</span> sensitivity to the regions of pulsar parameter space where a significant e{sup +}e{sup −} contribution is predicted, we find that a few known radio pulsars that have not yet been detected by Fermi can also significantly contribute to the local e{sup +}e{sup −} <span class="hlt">flux</span> if a) they are closer than 2 kpc, and if b) they have a characteristic age on the order of one mega-year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PPCF...57k5011P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PPCF...57k5011P"><span>Bi-Maxwellian <span class="hlt">electron</span> energy distribution function in the vicinity of the last closed <span class="hlt">flux</span> surface in fusion plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popov, T. S. V. K.; Dimitrova, M.; Pedrosa, M. A.; López-Bruna, D.; Horacek, J.; Kovačič, J.; Dejarnac, R.; Stöckel, J.; Aftanas, M.; Böhm, P.; Bílková, P.; Hidalgo, C.; Panek, R.</p> <p>2015-11-01</p> <p>The first-derivative probe technique was applied to derive data for plasma parameters from the IV Langmuir probe characteristics measured in the plasma boundary region in the COMPASS tokamak and in the TJ-II stellarator. It is shown that in the COMPASS tokamak in the vicinity of the last closed <span class="hlt">flux</span> surface (LCFS) the <span class="hlt">electron</span> energy distribution function (EEDF) is bi-Maxwellian with the low-temperature <span class="hlt">electron</span> fraction predominating over the higher temperature one, whereas in the far scrape-off layer (SOL) the EEDF is Maxwellian. In the TJ-II stellarator during NBI heated plasma the EEDF in the confined plasma and close to the LCFS is bi-Maxwellian while in the far SOL the EEDF is Maxwellian. In contrast, during the ECR heating phase of the discharge both in the confined plasma and in the SOL the EEDF is bi-Maxwellian. The mechanism for the appearance of a bi-Maxwellian EEDF in the vicinity of the LCFS is discussed. The comparison of the results from probe measurements with ASTRA package and EIRENE code calculations suggests that the main reason of the appearance of a bi-Maxwellian EEDF in the vicinity of the LCFS is the ionization of the neutral atoms. Results for the <span class="hlt">electron</span> temperatures and densities obtained by the first-derivative probe technique in the COMPASS tokamak and in the TJ-II stellarator were used to evaluate the radial distribution of the parallel power <span class="hlt">flux</span> density. It is shown that in the SOL the radial distribution of the parallel power <span class="hlt">flux</span> density is a double exponential. It is pointed out that in the calculations of the parallel power <span class="hlt">flux</span> density at the LCFS the energy losses from ionization mechanisms must be taken into account.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhRvB..51..381J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhRvB..51..381J"><span>Spin <span class="hlt">flux</span> and magnetic solitons in an interacting two-dimensional <span class="hlt">electron</span> gas: Topology of two-valued wave functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, Sajeev; Golubentsev, Andrey</p> <p>1995-01-01</p> <p>It is suggested that an interacting many-<span class="hlt">electron</span> system in a two-dimensional lattice may condense into a topological magnetic state distinct from any discussed previously. This condensate exhibits local spin-1/2 magnetic moments on the lattice sites but is composed of a Slater determinant of single-<span class="hlt">electron</span> wave functions which exist in an orthogonal sector of the <span class="hlt">electronic</span> Hilbert space from the sector describing traditional spin-density-wave or spiral magnetic states. These one-<span class="hlt">electron</span> spinor wave functions have the distinguishing property that they are antiperiodic along a closed path encircling any elementary plaquette of the lattice. This corresponds to a 2π rotation of the internal coordinate frame of the <span class="hlt">electron</span> as it encircles the plaquette. The possibility of spinor wave functions with spatial antiperiodicity is a direct consequence of the two-valuedness of the internal <span class="hlt">electronic</span> wave function defined on the space of Euler angles describing its spin. This internal space is the topologically, doubly-connected, group manifold of SO(3). Formally, these antiperiodic wave functions may be described by passing a <span class="hlt">flux</span> which couples to spin (rather than charge) through each of the elementary plaquettes of the lattice. When applied to the two-dimensional Hubbard model with one <span class="hlt">electron</span> per site, this new topological magnetic state exhibits a relativistic spectrum for charged, quasiparticle excitations with a suppressed one-<span class="hlt">electron</span> density of states at the Fermi level. For a topological antiferromagnet on a square lattice, with the standard Hartree-Fock, spin-density-wave decoupling of the on-site Hubbard interaction, there is an exact mapping of the low-energy one-<span class="hlt">electron</span> excitation spectrum to a relativistic Dirac continuum field theory. In this field theory, the Dirac mass gap is precisely the Mott-Hubbard charge gap and the continuum field variable is an eight-component Dirac spinor describing the components of physical <span class="hlt">electron</span>-spin amplitude on each of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22068828','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22068828"><span>Hot-<span class="hlt">electron</span> production and suprathermal heat <span class="hlt">flux</span> scaling with laser intensity from the two-plasmon-decay instability</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vu, H. X.; DuBois, D. F.; Myatt, J. F.; Russell, D. A.</p> <p>2012-10-15</p> <p>The fully kinetic reduced-description particle-in-cell (RPIC) method has been applied to simulations of two-plasmon-decay (TPD) instability, driven by crossed laser beams, in an inhomogeneous plasma for parameters consistent with recent direct-drive experiments related to laser-driven inertial fusion. The nonlinear saturated state is characterized by very spiky electric fields, with Langmuir cavitation occurring preferentially inside density channels produced by the ponderomotive beating of the crossed laser beams and the primary TPD Langmuir waves (LWs). The heated <span class="hlt">electron</span> distribution function is, in all cases, bi-Maxwellian, with instantaneous hot-<span class="hlt">electron</span> temperatures in the range 60-100 keV. The net hot-<span class="hlt">electron</span> energy <span class="hlt">flux</span> out of the system is a small fraction ({approx}1% to 2%) of the input laser intensity in these simulations. Scalings of the hot-<span class="hlt">electron</span> temperature and suprathermal heat <span class="hlt">flux</span> as functions of the laser intensity are obtained numerically from RPIC simulations. These simulations lead to the preliminary conclusion that Langmuir cavitation and collapse provide dissipation by producing suprathermal <span class="hlt">electrons</span>, which stabilize the system in saturation and drive the LW spectrum to the small dissipation scales at the Landau cutoff. The Langmuir turbulence originates at an <span class="hlt">electron</span> density 0.241 Multiplication-Sign the laser's critical density, where the crossed laser beams excite a 'triad' mode-a common forward LW plus a pair of backward LWs. Remnants of this 'triad' evolve in k-space and dominate the time-averaged energy spectrum. At times exceeding 10 ps, the excited Langmuir turbulence spreads toward lower densities. Comparisons of RPIC simulations with the extended Zakharov model are presented in appropriate regimes, and the necessary requirements for the validity of a quasi-linear Zakharov model (where the spatially averaged <span class="hlt">electron</span>-velocity distribution is evolved) are verified by RPIC simulation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NucFu..57b2009A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NucFu..57b2009A"><span>Gyrokinetic study of turbulent convection of heavy impurities in tokamak plasmas at comparable ion and <span class="hlt">electron</span> heat <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Angioni, C.; Bilato, R.; Casson, F. J.; Fable, E.; Mantica, P.; Odstrcil, T.; Valisa, M.; ASDEX Upgrade Team; Contributors, JET</p> <p>2017-02-01</p> <p>In tokamaks, the role of turbulent transport of heavy impurities, relative to that of neoclassical transport, increases with increasing size of the plasma, as clarified by means of general scalings, which use the ITER standard scenario parameters as reference, and by actual results from a selection of discharges from ASDEX Upgrade and JET. This motivates the theoretical investigation of the properties of the turbulent convection of heavy impurities by nonlinear gyrokinetic simulations in the experimentally relevant conditions of comparable ion and <span class="hlt">electron</span> heat <span class="hlt">fluxes</span>. These conditions also correspond to an intermediate regime between dominant ion temperature gradient turbulence and trapped <span class="hlt">electron</span> mode turbulence. At moderate plasma toroidal rotation, the turbulent convection of heavy impurities, computed with nonlinear gyrokinetic simulations, is found to be directed outward, in contrast to that obtained by quasi-linear calculations based on the most unstable linear mode, which is directed inward. In this mixed turbulence regime, with comparable <span class="hlt">electron</span> and ion heat <span class="hlt">fluxes</span>, the nonlinear results of the impurity transport can be explained by the coexistence of both ion temperature gradient and trapped <span class="hlt">electron</span> modes in the turbulent state, both contributing to the turbulent convection and diffusion of the impurity. The impact of toroidal rotation on the turbulent convection is also clarified.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1304819-improved-empirical-model-electron-ion-fluxes-geosynchronous-orbit-based-upstream-solar-wind-conditions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1304819-improved-empirical-model-electron-ion-fluxes-geosynchronous-orbit-based-upstream-solar-wind-conditions"><span>An improved empirical model of <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit based on upstream solar wind conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Denton, M. H.; Henderson, M. G.; Jordanova, V. K.; ...</p> <p>2016-07-01</p> <p>In this study, a new empirical model of the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides <span class="hlt">flux</span> predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the <span class="hlt">fluxes</span> at GEO with a ~1 h lead time. Model predictionsmore » are tested against in-sample observations from LANL satellites and also against out-of-sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC-12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root-mean-square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1304819','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1304819"><span>An improved empirical model of <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit based on upstream solar wind conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Denton, M. H.; Henderson, M. G.; Jordanova, V. K.; Thomsen, M. F.; Borovsky, J. E.; Woodroffe, J.; Hartley, D. P.; Pitchford, D.</p> <p>2016-07-01</p> <p>In this study, a new empirical model of the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides <span class="hlt">flux</span> predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the <span class="hlt">fluxes</span> at GEO with a ~1 h lead time. Model predictions are tested against in-sample observations from LANL satellites and also against out-of-sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC-12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root-mean-square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1304819','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1304819"><span>An improved empirical model of <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit based on upstream solar wind conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Denton, M. H.; Henderson, M. G.; Jordanova, V. K.; Thomsen, M. F.; Borovsky, J. E.; Woodroffe, J.; Hartley, D. P.; Pitchford, D.</p> <p>2016-07-01</p> <p>In this study, a new empirical model of the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides <span class="hlt">flux</span> predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the <span class="hlt">fluxes</span> at GEO with a ~1 h lead time. Model predictions are tested against in-sample observations from LANL satellites and also against out-of-sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC-12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root-mean-square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SpWea..14..511D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SpWea..14..511D"><span>An improved empirical model of <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit based on upstream solar wind conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, M. H.; Henderson, M. G.; Jordanova, V. K.; Thomsen, M. F.; Borovsky, J. E.; Woodroffe, J.; Hartley, D. P.; Pitchford, D.</p> <p>2016-07-01</p> <p>A new empirical model of the <span class="hlt">electron</span> <span class="hlt">fluxes</span> and ion <span class="hlt">fluxes</span> at geosynchronous orbit (GEO) is introduced, based on observations by Los Alamos National Laboratory (LANL) satellites. The model provides <span class="hlt">flux</span> predictions in the energy range ~1 eV to ~40 keV, as a function of local time, energy, and the strength of the solar wind electric field (the negative product of the solar wind speed and the z component of the magnetic field). Given appropriate upstream solar wind measurements, the model provides a forecast of the <span class="hlt">fluxes</span> at GEO with a ~1 h lead time. Model predictions are tested against in-sample observations from LANL satellites and also against out-of-sample observations from the Compact Environmental Anomaly Sensor II detector on the AMC-12 satellite. The model does not reproduce all structure seen in the observations. However, for the intervals studied here (quiet and storm times) the normalized root-mean-square deviation < ~0.3. It is intended that the model will improve forecasting of the spacecraft environment at GEO and also provide improved boundary/input conditions for physical models of the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810038140&hterms=Borg+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DBorg%2Bscale','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810038140&hterms=Borg+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DBorg%2Bscale"><span>Decrease of keV <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> in the dayside magnetosphere during the early phase of magnetospheric disturbances</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hultqvist, B.; Aparicio, B.; Borg, H.; Arnoldy, R.; Moore, T. E.</p> <p>1981-01-01</p> <p>It is shown that a decrease of the keV particle <span class="hlt">fluxes</span> in the dayside magnetosphere near the geosynchronous orbit is characteristic of the first several hours of magnetospheric disturbances. After some hours newly injected plasma from the nightside reaches the 'evacuated' regions of the dayside magnetosphere and strong <span class="hlt">flux</span> increases are observed. The 'evacuation' of the dayside magnetosphere is interpreted in terms of a change in the convection pattern associated with an increase of the large scale electric field at the onset of the disturbance. The model presented is capable of accommodating all characteristics of the observational data, such as the temporal and spatial distributions, energy and pitch angle characteristics, and differences between <span class="hlt">electrons</span> and protons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810038140&hterms=Aparicio&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAparicio','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810038140&hterms=Aparicio&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAparicio"><span>Decrease of keV <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> in the dayside magnetosphere during the early phase of magnetospheric disturbances</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hultqvist, B.; Aparicio, B.; Borg, H.; Arnoldy, R.; Moore, T. E.</p> <p>1981-01-01</p> <p>It is shown that a decrease of the keV particle <span class="hlt">fluxes</span> in the dayside magnetosphere near the geosynchronous orbit is characteristic of the first several hours of magnetospheric disturbances. After some hours newly injected plasma from the nightside reaches the 'evacuated' regions of the dayside magnetosphere and strong <span class="hlt">flux</span> increases are observed. The 'evacuation' of the dayside magnetosphere is interpreted in terms of a change in the convection pattern associated with an increase of the large scale electric field at the onset of the disturbance. The model presented is capable of accommodating all characteristics of the observational data, such as the temporal and spatial distributions, energy and pitch angle characteristics, and differences between <span class="hlt">electrons</span> and protons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM32A..08B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM32A..08B"><span>Prediction of Ultra-Relativistic <span class="hlt">Electron</span> <span class="hlt">Flux</span> Dynamics Through a Fusion of Machine-Learning and Physics-Based Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bortnik, J.; Ma, Q.; Chu, X.; Li, W.; Zhang, X.; Thorne, R. M.; Kletzing, C.; Hospodarsky, G. B.; Spence, H. E.; Reeves, G. D.; Kanekal, S. G.; Baker, D. N.</p> <p>2016-12-01</p> <p>The Earth's radiation belts are comprised of energetic <span class="hlt">electrons</span> with typical energies that are in the relativistic (>0.5 MeV) and ultra-relativistic range (>5 MeV or so). These radiation belts are a known hazard for spacecraft and hence represent an important societal concern, but they are also very interesting scientifically in that the processes that control the dynamics of the radiation belts are not fully understood. Typical approaches for predicting radiation belt dynamics involve either (1) physics-based modeling which requires global and time-dependent specification of boundary conditions and input parameters that are not always available, or (2) statistical predictive modeling which does not rely on a physics model, but requires a highly oversampled data set (i.e., large quantities of data) for accurate specification. When dealing with the ultra-relativistic range of <span class="hlt">electron</span> <span class="hlt">fluxes</span>, observations become sparse and predictive models become truly data starved so machine-learning techniques cannot be used directly. In this talk, we present a fusion between machine-learned models that specify the input parameters from a data-rich environment of lower-energy <span class="hlt">electrons</span> and waves, and a physics-based model that is able to dynamically use these inputs and calculate the <span class="hlt">fluxes</span> in the ultra-relativistic regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22228038','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22228038"><span>Dense plasma heating and Gbar shock formation by a high intensity <span class="hlt">flux</span> of energetic <span class="hlt">electrons</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ribeyre, X.; Feugeas, J.-L.; Nicolaï, Ph.; Tikhonchuk, V. T.; Gus'kov, S.</p> <p>2013-06-15</p> <p>Process of shock ignition in inertial confinement fusion implies creation of a high pressure shock with a laser spike having intensity of the order of a few PW/cm{sup 2}. However, the collisional (Bremsstrahlung) absorption at these intensities is inefficient and a significant part of laser energy is converted in a stream of energetic <span class="hlt">electrons</span>. The process of shock formation in a dense plasma by an intense <span class="hlt">electron</span> beam is studied in this paper in a planar geometry. The energy deposition takes place in a fixed mass target layer with the areal density determined by the <span class="hlt">electron</span> range. A self-similar isothermal rarefaction wave of a fixed mass describes the expanding plasma. Formation of a shock wave in the target under the pressure of expanding plasma is described. The efficiency of <span class="hlt">electron</span> beam energy conversion into the shock wave energy depends on the fast <span class="hlt">electron</span> energy and the pulse duration. The model is applied to the laser produced fast <span class="hlt">electrons</span>. The fast <span class="hlt">electron</span> energy transport could be the dominant mechanism of ablation pressure creation under the conditions of shock ignition. The shock wave pressure exceeding 1 Gbar during 200–300 ps can be generated with the <span class="hlt">electron</span> pulse intensity in the range of 5–10 PW/cm{sup 2}. The conclusions of theoretical model are confirmed in numerical simulations with a radiation hydrodynamic code coupled with a fast <span class="hlt">electron</span> transport module.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM24B..05O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM24B..05O"><span>Formation Process of Relativistic <span class="hlt">Electron</span> <span class="hlt">Flux</span> Through Interaction with Chorus Emissions in the Earth's Inner Magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Omura, Y.; Miyashita, Y.; Yoshikawa, M.; Summers, D.; Hikishima, M.; Ebihara, Y.; Kubota, Y.</p> <p>2015-12-01</p> <p>We perform test particle simulations of energetic <span class="hlt">electrons</span> interacting with whistler-mode chorus emissions. We compute trajectories of a large number of <span class="hlt">electrons</span> forming a delta function with the same energy and pitch angle. The <span class="hlt">electrons</span> are launched at different locations along the magnetic field line and different timings with respect to a pair of chorus emissions generated at the magnetic equator. We follow the evolution of the delta function, and obtain a distribution function in energy and equatorial pitch angle, which is a numerical Green's function for one cycle of chorus wave-particle interaction. We obtain the Green's functions for the energy range 10 keV ˜ 6 MeV and all pitch angles greater than the loss cone angle. By taking the convolution integral of the Green's functions with the distribution function of the injected <span class="hlt">electrons</span> repeatedly, we follow a long-time evolution of the distribution function. We find that the energetic <span class="hlt">electrons</span> are accelerated effectively by relativistic turning acceleration and ultra-relativistic acceleration through nonlinear trapping by chorus emissions, and that these processes result in the rapid formation of a dumbbell distribution of highly relativistic <span class="hlt">electrons</span> within a few minutes after the injection of tens of keV <span class="hlt">electrons</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22865398','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22865398"><span><span class="hlt">Electronic</span> <span class="hlt">fluxes</span> during Diels-Alder reactions involving 1,2-benzoquinones: mechanistic insights from the analysis of <span class="hlt">electron</span> localization function and catastrophe theory.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>González-Navarrete, Patricio; Domingo, Luis R; Andrés, Juan; Berski, Slawomir; Silvi, Bernard</p> <p>2012-11-15</p> <p>By means of the joint use of <span class="hlt">electron</span> localization function (ELF) and Thom's catastrophe theory, a theoretical analysis of the energy profile for the hetero-Diels-Alder reaction of 4-methoxy-1,2-benzoquinone 1 and methoxyethylene 2 has been carried out. The 12 different structural stability domains obtained by the bonding evolution theory have been identified as well as the bifurcation catastrophes (fold and cusp) responsible for the changes in the topology of the system. This analysis permits finding a relationship between the ELF topology and the evolution of the bond breaking/forming processes and <span class="hlt">electron</span> pair rearrangements through the reaction progress in terms of the different ways of pairing up the <span class="hlt">electrons</span>. The reaction mechanism corresponds to an asynchronous <span class="hlt">electronic</span> <span class="hlt">flux</span>; first, the O1-C5 bond is formed by the nucleophilic attack of the C5 carbon of the <span class="hlt">electron</span> rich ethylene 2 on the most electrophilically activated carbonyl O1 oxygen of 1, and once the σ bond has been completed, the formation process of the second O4C6 bond takes place. In addition, the values of the local electrophilicity and local nucleophilcity indices in the framework of conceptual density functional theory accounts for the asychronicity of the process as well as for the observed regioselectivity. Copyright © 2012 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APh....20..195K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APh....20..195K"><span>Limits on the ultra-high energy <span class="hlt">electron</span> neutrino <span class="hlt">flux</span> from the RICE experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kravchenko, I.; Frichter, G. M.; Miller, T.; Piccirillo, L.; Seckel, D.; Spiczak, G. M.; Adams, J.; Seunarine, S.; Allen, C.; Bean, A.; Besson, D.; Box, D. J.; Buniy, R.; Drees, J.; McKay, D.; Meyers, J.; Perry, L.; Ralston, J.; Razzaque, S.; Schmitz, D. W.</p> <p>2003-11-01</p> <p>Upper limits are presented on the diffuse <span class="hlt">flux</span> of ultra-high energy νe, based on analysis of data taken by the RICE experiment during August, 2000. The RICE receiver array at South Pole monitors cold ice for radio-wavelength Cherenkov radiation resulting from neutrino induced in-ice showers. For energies above 1 EeV, RICE is an effective detector of over 15 km 3 sr. Potential signal events are separated from backgrounds using vertex location, event reconstruction, and signal shape. These are the first terrestrial limits exploiting the physics of radio-Cherenkov emissions from charged current νe+ N→e+ N' interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2743R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2743R"><span>The observations of <span class="hlt">fluxes</span> of relativistic <span class="hlt">electrons</span> at the latitudes of the auroral oval: results of METEOR-M No.1</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riazantseva, Maria; Antonova, Elizaveta; Marjin, Boris; Barinova, Vera; Myagkova, Irina</p> <p></p> <p>We analyze the simultaneous observations of the <span class="hlt">fluxes</span> of auroral <span class="hlt">electrons</span> and the <span class="hlt">fluxes</span> of relativistic <span class="hlt">electrons</span> at the external boundary of the outer <span class="hlt">electron</span> radiation belts using data of METEOR-M No1 satellite for the period from November 3, 2009 till April 30, 2010. The geomagnetic conditions during analyzed period were comparatively quite. METEOR-M No.1 has a polar solar-synchronous circular orbit with an altitude of ~832 km, a period of 101.3 min, and an inclination of 98.068 degrees. The <span class="hlt">electrons</span> with the energies from 0.1 to 13 MeV and protons from 1 to 260 MeV were measured by GGAK-M instrument composed by semiconductor and scintillator detectors. The plasma <span class="hlt">electrons</span> with the energies from 0.03 to 16 keV were measured by the segment electrostatic analyzer. The observation of <span class="hlt">fluxes</span> of relativistic <span class="hlt">electrons</span> were selected inside the auroral oval connected with the development of magnetospheric substorms. However, the <span class="hlt">fluxes</span> of relativistic <span class="hlt">electrons</span> are also observed during absolutely quite time intervals. We compare the obtained results with the observations of CORONAS-FOTON satellite demonstrating the quasistationary (for more than 3 hours) increases of relativistic <span class="hlt">electrons</span> at the latitudes of the auroral oval and argue that the processes inside the auroral oval can play the considerable role in the acceleration of relativistic <span class="hlt">electrons</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3925999','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3925999"><span>Fluctuations in the <span class="hlt">electron</span> system of a superconductor exposed to a photon <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>de Visser, P. J.; Baselmans, J. J. A.; Bueno, J.; Llombart, N.; Klapwijk, T. M.</p> <p>2014-01-01</p> <p>In a superconductor, in which <span class="hlt">electrons</span> are paired, the density of unpaired <span class="hlt">electrons</span> should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the <span class="hlt">electron</span> system of the superconductor to pair-breaking photons, microwave photons and varying temperatures. A large range in radiation power (at 1.54 THz) can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the <span class="hlt">electron</span> system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48±8%) and showing an unprecedented detector sensitivity. At low radiation power, fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime. PMID:24496036</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24496036','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24496036"><span>Fluctuations in the <span class="hlt">electron</span> system of a superconductor exposed to a photon <span class="hlt">flux</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Visser, P J; Baselmans, J J A; Bueno, J; Llombart, N; Klapwijk, T M</p> <p>2014-01-01</p> <p>In a superconductor, in which <span class="hlt">electrons</span> are paired, the density of unpaired <span class="hlt">electrons</span> should become zero when approaching zero temperature. Therefore, radiation detectors based on breaking of pairs promise supreme sensitivity, which we demonstrate using an aluminium superconducting microwave resonator. Here we show that the resonator also enables the study of the response of the <span class="hlt">electron</span> system of the superconductor to pair-breaking photons, microwave photons and varying temperatures. A large range in radiation power (at 1.54 THz) can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the <span class="hlt">electron</span> system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48 ± 8%) and showing an unprecedented detector sensitivity. At low radiation power, fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4584955','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4584955"><span>Partially dissecting the steady-state <span class="hlt">electron</span> <span class="hlt">fluxes</span> in Photosystem I in wild-type and pgr5 and ndh mutants of Arabidopsis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kou, Jiancun; Takahashi, Shunichi; Fan, Da-Yong; Badger, Murray R.; Chow, Wah S.</p> <p>2015-01-01</p> <p>Cyclic <span class="hlt">electron</span> <span class="hlt">flux</span> (CEF) around Photosystem I (PS I) is difficult to quantify. We obtained the linear <span class="hlt">electron</span> <span class="hlt">flux</span> (LEFO2) through both photosystems and the total <span class="hlt">electron</span> <span class="hlt">flux</span> through PS I (ETR1) in Arabidopsis in CO2-enriched air. Δ<span class="hlt">Flux</span> = ETR1 – LEFO2 is an upper estimate of CEF, which consists of two components, an antimycin A-sensitive, PGR5 (proton gradient regulation 5 protein)-dependent component and an insensitive component facilitated by a chloroplastic nicotinamide adenine dinucleotide dehydrogenase-like complex (NDH). Using wild type as well as pgr5 and ndh mutants, we observed that (1) 40% of the absorbed light was partitioned to PS I; (2) at high irradiance a substantial antimycin A-sensitive CEF occurred in the wild type and the ndh mutant; (3) at low irradiance a sizable antimycin A-sensitive CEF occurred in the wild type but not in the ndh mutant, suggesting an enhancing effect of NDH in low light; and (4) in the pgr5 mutant, and the wild type and ndh mutant treated with antimycin A, a residual Δ<span class="hlt">Flux</span> existed at high irradiance, attributable to charge recombination and/or pseudo-cyclic <span class="hlt">electron</span> flow. Therefore, in low-light-acclimated plants exposed to high light, Δ<span class="hlt">Flux</span> has contributions from various paths of <span class="hlt">electron</span> flow through PS I. PMID:26442071</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...120m4308O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...120m4308O"><span>Crystallization of sputter-deposited amorphous Ge films by <span class="hlt">electron</span> irradiation: Effect of low-<span class="hlt">flux</span> pre-irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Okugawa, M.; Nakamura, R.; Ishimaru, M.; Yasuda, H.; Numakura, H.</p> <p>2016-10-01</p> <p>We investigated the effect of low-<span class="hlt">flux</span> <span class="hlt">electron</span> irradiation with 125 keV to sputter-deposited amorphous germanium on the amorphous structure and <span class="hlt">electron</span>-induced crystallization microstructure by TEM following our previous study on the effect of aging at room temperature. In samples aged for 3 days, coarse, spherical particles about 100 nm in diameter appear dominantly. By low-<span class="hlt">flux</span> pre-irradiation to the samples, a reduction in the size and number of coarse particles, embedded in the matrix with fine nanograins of the diamond cubic structure, was noted with the increase in fluence. The crystal structure of these coarse particles was found to be not cubic but hexagonal. In samples aged for 4 months, a similar tendency was observed. In samples aged for 7 months, on the other hand, the homogeneous diamond cubic structured nanograins were unchanged by pre-irradiation. These results indicate that pre-irradiation as well as aging modifies the amorphous structure, preventing the appearance of a hexagonal phase. The elimination of a certain amount of medium-range ordered clusters by pre-irradiation, included in as-deposited samples and the samples aged for 4 months, apparently gives rise to a reduction in the size and number of coarse particles with a metastable hexagonal structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16732470','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16732470"><span>The ROS production induced by a reverse-<span class="hlt">electron</span> <span class="hlt">flux</span> at respiratory-chain complex 1 is hampered by metformin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Batandier, Cécile; Guigas, Bruno; Detaille, Dominique; El-Mir, M-Yehia; Fontaine, Eric; Rigoulet, M; Leverve, Xavier M</p> <p>2006-02-01</p> <p>Mitochondrial reactive oxygen species (ROS) production was investigated in mitochondria extracted from liver of rats treated with or without metformin, a mild inhibitor of respiratory chain complex 1 used in type 2 diabetes. A high rate of ROS production, fully suppressed by rotenone, was evidenced in non-phosphorylating mitochondria in the presence of succinate as a single complex 2 substrate. This ROS production was substantially lowered by metformin pretreatment and by any decrease in membrane potential (Delta Phi(m)), redox potential (NADH/NAD), or phosphate potential, as induced by malonate, 2,4-dinitrophenol, or ATP synthesis, respectively. ROS production in the presence of glutamate-malate plus succinate was lower than in the presence of succinate alone, but higher than in the presence of glutamate-malate. Moreover, while rotenone both increased and decreased ROS production at complex 1 depending on forward (glutamate-malate) or reverse (succinate) <span class="hlt">electron</span> <span class="hlt">flux</span>, no ROS overproduction was evidenced in the forward direction with metformin. Therefore, we propose that reverse <span class="hlt">electron</span> <span class="hlt">flux</span> through complex 1 is an alternative pathway, which leads to a specific metformin-sensitive ROS production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22482895','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22482895"><span>Investigation on the <span class="hlt">electron</span> <span class="hlt">flux</span> to the wall in the VENUS ion source</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thuillier, T. Angot, J.</p> <p>2016-02-15</p> <p>The long-term operation of high charge state <span class="hlt">electron</span> cyclotron resonance ion sources fed with high microwave power has caused damage to the plasma chamber wall in several laboratories. Porosity, or a small hole, can be progressively created in the chamber wall which can destroy the plasma chamber over a few year time scale. A burnout of the VENUS plasma chamber is investigated in which the hole formation in relation to the local hot <span class="hlt">electron</span> power density is studied. First, the results of a simple model assuming that hot <span class="hlt">electrons</span> are fully magnetized and strictly following magnetic field lines are presented. The model qualitatively reproduces the experimental traces left by the plasma on the wall. However, it is too crude to reproduce the localized <span class="hlt">electron</span> power density for creating a hole in the chamber wall. Second, the results of a Monte Carlo simulation, following a population of scattering hot <span class="hlt">electrons</span>, indicate a localized high power deposited to the chamber wall consistent with the hole formation process. Finally, a hypervapotron cooling scheme is proposed to mitigate the hole formation in <span class="hlt">electron</span> cyclotron resonance plasma chamber wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87bA736T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87bA736T"><span>Investigation on the <span class="hlt">electron</span> <span class="hlt">flux</span> to the wall in the VENUS ion source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thuillier, T.; Angot, J.; Benitez, J. Y.; Hodgkinson, A.; Lyneis, C. M.; Todd, D. S.; Xie, D. Z.</p> <p>2016-02-01</p> <p>The long-term operation of high charge state <span class="hlt">electron</span> cyclotron resonance ion sources fed with high microwave power has caused damage to the plasma chamber wall in several laboratories. Porosity, or a small hole, can be progressively created in the chamber wall which can destroy the plasma chamber over a few year time scale. A burnout of the VENUS plasma chamber is investigated in which the hole formation in relation to the local hot <span class="hlt">electron</span> power density is studied. First, the results of a simple model assuming that hot <span class="hlt">electrons</span> are fully magnetized and strictly following magnetic field lines are presented. The model qualitatively reproduces the experimental traces left by the plasma on the wall. However, it is too crude to reproduce the localized <span class="hlt">electron</span> power density for creating a hole in the chamber wall. Second, the results of a Monte Carlo simulation, following a population of scattering hot <span class="hlt">electrons</span>, indicate a localized high power deposited to the chamber wall consistent with the hole formation process. Finally, a hypervapotron cooling scheme is proposed to mitigate the hole formation in <span class="hlt">electron</span> cyclotron resonance plasma chamber wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26931954','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26931954"><span>Investigation on the <span class="hlt">electron</span> <span class="hlt">flux</span> to the wall in the VENUS ion source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thuillier, T; Angot, J; Benitez, J Y; Hodgkinson, A; Lyneis, C M; Todd, D S; Xie, D Z</p> <p>2016-02-01</p> <p>The long-term operation of high charge state <span class="hlt">electron</span> cyclotron resonance ion sources fed with high microwave power has caused damage to the plasma chamber wall in several laboratories. Porosity, or a small hole, can be progressively created in the chamber wall which can destroy the plasma chamber over a few year time scale. A burnout of the VENUS plasma chamber is investigated in which the hole formation in relation to the local hot <span class="hlt">electron</span> power density is studied. First, the results of a simple model assuming that hot <span class="hlt">electrons</span> are fully magnetized and strictly following magnetic field lines are presented. The model qualitatively reproduces the experimental traces left by the plasma on the wall. However, it is too crude to reproduce the localized <span class="hlt">electron</span> power density for creating a hole in the chamber wall. Second, the results of a Monte Carlo simulation, following a population of scattering hot <span class="hlt">electrons</span>, indicate a localized high power deposited to the chamber wall consistent with the hole formation process. Finally, a hypervapotron cooling scheme is proposed to mitigate the hole formation in <span class="hlt">electron</span> cyclotron resonance plasma chamber wall.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/803888','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803888"><span>An evaluation of enhanced cooling techniques for <span class="hlt">high-heat</span> load absorbers.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sharma, S.; Doose, C.; Rotela, E.; Barickowski, A.</p> <p>2002-10-28</p> <p>Many components of the storage ring and front ends in the third generation of light sources are subjected to <span class="hlt">high</span> <span class="hlt">heat</span> loads from intense x-rays. Temperature rises and thermal stresses in these components must be kept within acceptable limits of critical heat <span class="hlt">flux</span> and low-cycle fatigue failure. One of the design solutions is to improve heat transfer to the cooling water either by increasing water velocity in the cooling channels or by using inserts, such as porous media, twisted tapes and wire springs. In this paper we present experimental and analytical results to compare various enhanced cooling techniques for conditions specific to heating from an x-ray fan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JVSJ...53..132W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JVSJ...53..132W"><span>Ion <span class="hlt">Flux</span> Impingement on the Cathode Surface in an Axisymmetric <span class="hlt">Electron</span> Gun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watanabe, Masaya; Kusumoto, Yoshiro</p> <p></p> <p>The flow of the residual gas ion generated by a collision with high-energy <span class="hlt">electron</span> in an axisymmetric gun was numerically investigated. Since the lifetime of the gun is dominated by the cathode damage induced by the ion bombardment, it is of industrial importance to reveal how the ions impinge on the cathode and how the inflow can be repelled. Under the normal operating condition of the <span class="hlt">electron</span> gun (40 kV, 6 A), we determined the inflow basin, i.e. the region where the gas ions were born there and finally reached to the cathode. The basin consisted of four separated zones characterized by the potential distribution on the beam axis. To eliminate the downstream zones, it was useful to append a positive voltage imposed electrode behind the anode. The voltage necessary for repelling the ion inflow was found to be 300 V being less than 1% of the <span class="hlt">electron</span> acceleration voltage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NucFu..55a3015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NucFu..55a3015C"><span>Dynamics of multiple <span class="hlt">flux</span> tubes in sawtoothing KSTAR plasmas heated by <span class="hlt">electron</span> cyclotron waves: I. Experimental analysis of the tube structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choe, G. H.; Yun, G. S.; Nam, Y.; Lee, W.; Park, H. K.; Bierwage, A.; Domier, C. W.; Luhmann, N. C., Jr.; Jeong, J. H.; Bae, Y. S.; the KSTAR Team</p> <p>2015-01-01</p> <p>Multiple (two or more) <span class="hlt">flux</span> tubes are commonly observed inside and/or near the q = 1 <span class="hlt">flux</span> surface in KSTAR tokamak plasmas with localized <span class="hlt">electron</span> cyclotron resonance heating and current drive (ECH/CD). Detailed 2D and quasi-3D images of the <span class="hlt">flux</span> tubes obtained by an advanced imaging diagnostic system showed that the <span class="hlt">flux</span> tubes are m/n = 1/1 field-aligned structures co-rotating around the magnetic axis. The <span class="hlt">flux</span> tubes typically merge together and become like the internal kink mode of the usual sawtooth, which then collapses like a usual sawtooth crash. A systematic scan of ECH/CD beam position showed a strong correlation with the number of <span class="hlt">flux</span> tubes. In the presence of multiple <span class="hlt">flux</span> tubes close to the q = 1 surface, the radially outward heat transport was enhanced, which explains naturally temporal changes of <span class="hlt">electron</span> temperature. We emphasize that the multiple <span class="hlt">flux</span> tubes are a universal feature distinct from the internal kink instability and play a critical role in the control of sawteeth using ECH/CD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhLA..381.3066C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhLA..381.3066C"><span>Geodesic mode instability driven by <span class="hlt">electron</span> and ion <span class="hlt">fluxes</span> during neutral beam injection in tokamaks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Camilo de Souza, F.; Elfimov, A. G.; Galvão, R. M. O.; Krbec, J.; Seidl, J.; Stöckel, J.; Hron, M.; Havlicek, J.; Mitosinkova, K.</p> <p>2017-09-01</p> <p>The effect of a minor concentration of energetic particles produced by parallel NB injection on Geodesic Acoustic Modes (GAM) spectrum is analyzed using fully kinetic equation. It is found that the GAM frequency is reduced by the effective mass renormalization due to that new energetic GAM appears with higher frequency. The <span class="hlt">electron</span> current in combination with NB driven ion flow, modeled by shifted Maxwell distribution, may overcome the ion Landau damping thus resulting in the GAM instability when <span class="hlt">electron</span> current velocity is larger than the effective parallel GAM phase velocity Rqω. Qualitative agreement of the theory with co/counter NB injection experiments in COMPASS tokamak is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7179446','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7179446"><span>Enhancement of single-phase heat transfer and critical heat <span class="hlt">flux</span> from an ultra-high-<span class="hlt">flux</span> simulated microelectronic heat source to a rectangular impinging jet of dielectric liquid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wadsworth, D.C.; Mudawar, I. )</p> <p>1992-08-01</p> <p>Jet impingement is encountered in numerous applications demanding <span class="hlt">high</span> <span class="hlt">heating</span> or cooling <span class="hlt">fluxes</span>. Examples include annealing of metal sheets and cooling of turbine blades, x-ray medical devices, laser weapons, and fusion blankets. The attractive heat transfer attributes of jet impingement have also stimulated research efforts on cooling of <span class="hlt">high-heat-flux</span> microelectronic devices. These devices are fast approaching heat <span class="hlt">fluxes</span> in excess of 100 W/cm[sup 2], which have to be dissipated using coolants that are both electrically and chemically compatible with <span class="hlt">electronic</span> components. Unfortunately, fluids satisfying these requirements tend to possess poor transport properties, creating a need for significant enhancement in the heat transfer coefficient by such means as increased coolant flow rate and phase change. The cooling problem is compounded by a need to cool large arrays of heat sources in minimal volume, and to reduce the spacing between adjacent circuit boards. These requirements place severe constraints on the packaging of jet impingement cooling hardware.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1031886','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1031886"><span>Reduced Heat <span class="hlt">Flux</span> Through Preferential Surface Reactions Leading to Vibrationally and <span class="hlt">Electronically</span> Excited Product States</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-03-04</p> <p>computational chemistry approaches, capable of modeling nonadiabatic oxygen interactions (<span class="hlt">electronically</span> excited interactions) with surface defects...were developed. Through such computational chemistry modeling we determined precisely how and why such excited-state molecules are produced, by...to interpret the experimental data. The third objective was to develop new computational chemistry approaches capable of modeling the challenging</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990P%26SS...38.1295B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990P%26SS...38.1295B"><span>Auroral precipitation <span class="hlt">flux</span> of ions and <span class="hlt">electrons</span> in Saturn's outer magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barbosa, D. D.</p> <p>1990-10-01</p> <p>This paper examines particles and fields data obtained by Voyager in Saturn's outer magnetosphere with a view toward assessing the role that medium-energy ions and <span class="hlt">electrons</span> have in stimulating the UV aurora. The magnetic field displays a high level of fluctuation of two characteristic types: large-scale coherent depressions in the field strength associated with the plumes of Titan and a small-scale incoherent turbulence presumed to be a consequence of the high-beta plasma environment. <span class="hlt">Electrons</span> are assumed to interact strongly with lower hybrid waves and are accelerated to energies of a few kiloelectron volts. The available energy input to the aurora by protons is 5 x 10 to the 9th W, while an upper bound to that of N(+) ions is about 2 x 10 to the 10th W. <span class="hlt">Electrons</span> in the range 1-10 keV can contribute upward of 5 x 10 to the 10th W and perhaps more if a field-aligned potential drop above the aurora is present. It is concluded that <span class="hlt">electrons</span> are most likely the primary precipitation energy source for the aurora as a result of energy transfer from Titanogenic N(+) pickup ions in a corotation-dominated magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000088491','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000088491"><span>Thermal Conductivity of EB-PVD Thermal Barrier Coatings Evaluated by a Steady-State Laser Heat <span class="hlt">Flux</span> Technique</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhu, Dongming; Miller, Robert A.; Nagaraj, Ben A.; Bruce, Robert W.</p> <p>2000-01-01</p> <p>The thermal conductivity of <span class="hlt">electron</span> beam-physical vapor deposited (EB-PVD) Zr02-8wt%Y2O3 thermal barrier coatings was determined by a steady-state heat <span class="hlt">flux</span> laser technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span>, long term test conditions. The thermal conductivity increase due to micro-pore sintering and the decrease due to coating micro-delaminations in the EB-PVD coatings were evaluated for grooved and non-grooved EB-PVD coating systems under isothermal and thermal cycling conditions. The coating failure modes under the <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> test conditions were also investigated. The test technique provides a viable means for obtaining coating thermal conductivity data for use in design, development, and life prediction for engine applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/874724','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/874724"><span>Fast <span class="hlt">flux</span> locked loop</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ganther, Jr., Kenneth R.; Snapp, Lowell D.</p> <p>2002-09-10</p> <p>A <span class="hlt">flux</span> locked loop for providing an electrical feedback signal, the <span class="hlt">flux</span> locked loop employing radio-frequency components and technology to extend the <span class="hlt">flux</span> modulation frequency and tracking loop bandwidth. The <span class="hlt">flux</span> locked loop of the present invention has particularly useful application in read-out <span class="hlt">electronics</span> for DC SQUID magnetic measurement systems, in which case the electrical signal output by the <span class="hlt">flux</span> locked loop represents an unknown magnetic <span class="hlt">flux</span> applied to the DC SQUID.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/632552','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/632552"><span>Onset of diffuse reflectivity and fast <span class="hlt">electron</span> <span class="hlt">flux</span> inhibition in 528-nm-laser{endash}solid interactions at ultrahigh intensity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Feurer, T.; Theobald, W.; Sauerbrey, R.; Uschmann, I.; Altenbernd, D.; Teubner, U.; Gibbon, P.; Foerster, E.; Malka, G.; Miquel, J.L.</p> <p>1997-10-01</p> <p>Using a high-power femtosecond frequency-doubled Nd:glass laser system with a contrast ratio of 10{sup 12}, the interaction between light and matter up to intensities of 10{sup 19} Wthinspcm{sup {minus}2}has been investigated. The absorption of the laser light in solid aluminum is almost independent of the polarization, peaks at about 25{degree}, and reaches values of almost 45{percent}. Assuming an exponential <span class="hlt">electron</span> distribution, a temperature of 420 keV at 4{times}10{sup 18} Wthinspcm{sup {minus}2}was measured. These experiments and the detection of the hard-x-ray radiation (60 keV{endash}1 MeV) implied a conversion efficiency of 10{sup {minus}4}{endash}10{sup {minus}3} into suprathermal <span class="hlt">electrons</span>. A second low-energy <span class="hlt">electron</span> distribution either with trajectories mainly parallel to the target surface or with a reduced penetration depth due to <span class="hlt">flux</span> inhibition was also inferred from K{alpha} line radiation measurements. {copyright} {ital 1997} {ital The American Physical Society}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26846653','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26846653"><span>Obstacles in the quantification of the cyclic <span class="hlt">electron</span> <span class="hlt">flux</span> around Photosystem I in leaves of C3 plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fan, Da-Yong; Fitzpatrick, Duncan; Oguchi, Riichi; Ma, Weimin; Kou, Jiancun; Chow, Wah Soon</p> <p>2016-09-01</p> <p>Sixty years ago Arnon and co-workers discovered photophosphorylation driven by a cyclic <span class="hlt">electron</span> <span class="hlt">flux</span> (CEF) around Photosystem I. Since then understanding the physiological roles and the regulation of CEF has progressed, mainly via genetic approaches. One basic problem remains, however: quantifying CEF in the absence of a net product. Quantification of CEF under physiological conditions is a crucial prerequisite for investigating the physiological roles of CEF. Here we summarize current progress in methods of CEF quantification in leaves and, in some cases, in isolated thylakoids, of C3 plants. Evidently, all present methods have their own shortcomings. We conclude that to quantify CEF in vivo, the best way currently is to measure the <span class="hlt">electron</span> <span class="hlt">flux</span> through PS I (ETR1) and that through PS II and PS I in series (ETR2) for the whole leaf tissue under identical conditions. The difference between ETR1 and ETR2 is an upper estimate of CEF, mainly consisting, in C3 plants, of a major PGR5-PGRL1-dependent CEF component and a minor chloroplast NDH-dependent component, where PGR5 stands for Proton Gradient Regulation 5 protein, PGRL1 for PGR5-like photosynthesis phenotype 1, and NDH for Chloroplast NADH dehydrogenase-like complex. These two CEF components can be separated by the use of antimycin A to inhibit the former (major) component. Membrane inlet mass spectrometry utilizing stable oxygen isotopes provides a reliable estimation of ETR2, whilst ETR1 can be estimated from a method based on the photochemical yield of PS I, Y(I). However, some issues for the recommended method remain unresolved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561719','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561719"><span>Rerouting Cellular <span class="hlt">Electron</span> <span class="hlt">Flux</span> To Increase the Rate of Biological Methane Production</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Catlett, Jennie L.; Ortiz, Alicia M.</p> <p>2015-01-01</p> <p>Methanogens are anaerobic archaea that grow by producing methane, a gas that is both an efficient renewable fuel and a potent greenhouse gas. We observed that overexpression of the cytoplasmic heterodisulfide reductase enzyme HdrABC increased the rate of methane production from methanol by 30% without affecting the growth rate relative to the parent strain. Hdr enzymes are essential in all known methane-producing archaea. They function as the terminal oxidases in the methanogen <span class="hlt">electron</span> transport system by reducing the coenzyme M (2-mercaptoethane sulfonate) and coenzyme B (7-mercaptoheptanoylthreonine sulfonate) heterodisulfide, CoM-S-S-CoB, to regenerate the thiol-coenzymes for reuse. In Methanosarcina acetivorans, HdrABC expression caused an increased rate of methanogenesis and a decrease in metabolic efficiency on methylotrophic substrates. When acetate was the sole carbon and energy source, neither deletion nor overexpression of HdrABC had an effect on growth or methane production rates. These results suggest that in cells grown on methylated substrates, the cell compensates for energy losses due to expression of HdrABC with an increased rate of substrate turnover and that HdrABC lacks the appropriate <span class="hlt">electron</span> donor in acetate-grown cells. PMID:26162885</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26162885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26162885"><span>Rerouting Cellular <span class="hlt">Electron</span> <span class="hlt">Flux</span> To Increase the Rate of Biological Methane Production.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Catlett, Jennie L; Ortiz, Alicia M; Buan, Nicole R</p> <p>2015-10-01</p> <p>Methanogens are anaerobic archaea that grow by producing methane, a gas that is both an efficient renewable fuel and a potent greenhouse gas. We observed that overexpression of the cytoplasmic heterodisulfide reductase enzyme HdrABC increased the rate of methane production from methanol by 30% without affecting the growth rate relative to the parent strain. Hdr enzymes are essential in all known methane-producing archaea. They function as the terminal oxidases in the methanogen <span class="hlt">electron</span> transport system by reducing the coenzyme M (2-mercaptoethane sulfonate) and coenzyme B (7-mercaptoheptanoylthreonine sulfonate) heterodisulfide, CoM-S-S-CoB, to regenerate the thiol-coenzymes for reuse. In Methanosarcina acetivorans, HdrABC expression caused an increased rate of methanogenesis and a decrease in metabolic efficiency on methylotrophic substrates. When acetate was the sole carbon and energy source, neither deletion nor overexpression of HdrABC had an effect on growth or methane production rates. These results suggest that in cells grown on methylated substrates, the cell compensates for energy losses due to expression of HdrABC with an increased rate of substrate turnover and that HdrABC lacks the appropriate <span class="hlt">electron</span> donor in acetate-grown cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22314277','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22314277"><span>Compact and high-particle-<span class="hlt">flux</span> thermal-lithium-beam probe system for measurement of two-dimensional <span class="hlt">electron</span> density profile</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shibata, Y. Manabe, T.; Ohno, N.; Takagi, M.; Kajita, S.; Tsuchiya, H.; Morisaki, T.</p> <p>2014-09-15</p> <p>A compact and high-particle-<span class="hlt">flux</span> thermal-lithium-beam source for two-dimensional measurement of <span class="hlt">electron</span> density profiles has been developed. The thermal-lithium-beam oven is heated by a carbon heater. In this system, the maximum particle <span class="hlt">flux</span> of the thermal lithium beam was ∼4 × 10{sup 19} m{sup −2} s{sup −1} when the temperature of the thermal-lithium-beam oven was 900 K. The <span class="hlt">electron</span> density profile was evaluated in the small tokamak device HYBTOK-II. The <span class="hlt">electron</span> density profile was reconstructed using the thermal-lithium-beam probe data and this profile was consistent with the <span class="hlt">electron</span> density profile measured with a Langmuir electrostatic probe. We confirm that the developed thermal-lithium-beam probe can be used to measure the two-dimensional <span class="hlt">electron</span> density profile with high time and spatial resolutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090007929&hterms=galileo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgalileo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090007929&hterms=galileo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgalileo"><span>Analysis of the Variation of Energetic <span class="hlt">Electron</span> <span class="hlt">Flux</span> with Respect to Longitude and Distance Normal to the Magnetic Equatorial Plane for Galileo Energetic Particle Detector Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Swimm, Randall; Garrett, Henry B.; Jun, Insoo; Evans, Robin W.</p> <p>2004-01-01</p> <p>In this study we examine ten-minute omni-directional averages of energetic <span class="hlt">electron</span> data measured by the Galileo spacecraft Energetic Particle Detector (EPD). Count rates from <span class="hlt">electron</span> channels B1, DC2, and DC3 are evaluated using a power law model to yield estimates of the differential <span class="hlt">electron</span> <span class="hlt">fluxes</span> from 1 MeV to 11 MeV at distances between 8 and 51 Jupiter radii. Whereas the orbit of the Galileo spacecraft remained close to the rotational equatorial plane of Jupiter, the approximately 11 degree tilt of the magnetic axis of Jupiter relative to its rotational axis allowed the EPD instrument to sample high energy <span class="hlt">electrons</span> at limited distances normal to the magnetic equatorial plane. We present a Fourier analysis of the semi-diurnal variation of <span class="hlt">electron</span> <span class="hlt">fluxes</span> with longitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090007929&hterms=particle+detector&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dparticle%2Bdetector','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090007929&hterms=particle+detector&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dparticle%2Bdetector"><span>Analysis of the Variation of Energetic <span class="hlt">Electron</span> <span class="hlt">Flux</span> with Respect to Longitude and Distance Normal to the Magnetic Equatorial Plane for Galileo Energetic Particle Detector Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Swimm, Randall; Garrett, Henry B.; Jun, Insoo; Evans, Robin W.</p> <p>2004-01-01</p> <p>In this study we examine ten-minute omni-directional averages of energetic <span class="hlt">electron</span> data measured by the Galileo spacecraft Energetic Particle Detector (EPD). Count rates from <span class="hlt">electron</span> channels B1, DC2, and DC3 are evaluated using a power law model to yield estimates of the differential <span class="hlt">electron</span> <span class="hlt">fluxes</span> from 1 MeV to 11 MeV at distances between 8 and 51 Jupiter radii. Whereas the orbit of the Galileo spacecraft remained close to the rotational equatorial plane of Jupiter, the approximately 11 degree tilt of the magnetic axis of Jupiter relative to its rotational axis allowed the EPD instrument to sample high energy <span class="hlt">electrons</span> at limited distances normal to the magnetic equatorial plane. We present a Fourier analysis of the semi-diurnal variation of <span class="hlt">electron</span> <span class="hlt">fluxes</span> with longitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM21A2445S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM21A2445S"><span>Differential <span class="hlt">Electron</span> <span class="hlt">Flux</span> Spectra Measured by the Magnetospheric Multiscale Mission (MMS) Show Strong Field-aligned <span class="hlt">Electron</span> Population of Ionospheric Origin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiff, C.; Khazanov, G. V.; Giles, B. L.; Avanov, L. A.; Burch, J. L.; Coffey, V. N.; Dorelli, J.; Gershman, D. J.; Lavraud, B.; Moore, T. E.; Paterson, W. R.; Pollock, C. J.; Russell, C. T.; Strangeway, R. J.</p> <p>2016-12-01</p> <p>Ionospheric outflow is the process in which neutral atoms in the Earth's atmosphere are first ionized and then accelerated so that the component ions and <span class="hlt">electrons</span> can transport from regions of low altitude (h 0.5 RE) into the magnetosphere, reaching distances ranging up to 15 RE and beyond. It is an important process in atmospheric loss that is only partially understood and refinements of the theory by experimental observation is crucial to developing a better understanding its role in the long-term fate of the Earth's atmosphere. In addition, it is a source of various plasma populations (in particular O+) whose influence on the interaction between the magnetosphere and the solar wind must be accounted for in order to get an accurate picture of the relevant plasma dynamics. In this study, fast survey measurements (4.5 s) from the Fast Plasma Investigation (FPI) <span class="hlt">electron</span> spectrometers onboard the MMS spacecraft are used to construct differential <span class="hlt">electron</span> <span class="hlt">flux</span>, Φe, spectra over the energy range from 10 eV to 30 KeV. The time period of the study is from 04:00 to 06:00 UTC on Oct. 26, 2015, when the MMS formation was approximately at 10 RE and at a local time of about 14:00. Using the 32x16 angular resolution (angular bins of 11.25 degrees) of an FPI skymap, these spectra are further refined by binning pitch angles, α, every 20 degrees. The resulting spectra show a very large population of cold <span class="hlt">electrons</span> (Φe ≈ 106 s-1 cm-2 eV-1) at low energies (10-60 eV) that are strongly aligned with the magnetic field (counterstreaming with a density 3 times larger than the perpendicular population). The distribution, which falls off rapidly with increasing energy, exhibits a knee at about 100 eV, indicative of where the magnetospheric population becomes dominant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26992792','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26992792"><span>Modifying the endogenous <span class="hlt">electron</span> <span class="hlt">fluxes</span> of Rhodobacter sphaeroides 2.4.1 for improved electricity generation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wong, Man Tung; Cheng, Danhui; Wang, Ri; Hsing, I-Ming</p> <p>2016-05-01</p> <p>The purple bacteria Rhodobacter sphaeroides serve as a promising biocatalyst in the photo-microbial fuel cell system (photo-MFC). This gram-negative species performs highly efficient anoxygenic photosynthesis that ensures an anaerobic environment in the anode compartment. Previous studies incorporating R. sphaeroides into photo-MFC were conducted using platinum as the anode electrode. In this study, we detected a steady current generation of R. sphaeroides in a bioelectrochemical system where glassy carbon was the working electrode and a typical growth medium was the electrolyte. The bioelectricity generation synchronized with the supplementation of reduced carbon source and showed immediate response to illumination, which strongly indicated the correlation between the observed current and the cytoplasmic quinone activity. Modifications of the endogenous <span class="hlt">electron</span> flows mediated by quinone pool are shown to have significantly enhanced the bioelectricity generation. We anticipate that the findings in this study would advance future optimization of R. sphaeroides as an anode strain, as well as facilitate the study of bioenergetics in photosynthetic bacteria.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM31A2438D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM31A2438D"><span>On the ultra-low frequency wave contributions to the relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> dynamics in the outer Van Allen radiation belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dal Lago, A.; Marchezi, J. P.; Alves, L. R.; da Silva, L.; Dallaqua, R.; Medeiros, C.; Souza, V. M. C. E. S.; Rockenbach, M.; Vieira, L.; Mendes, O., Jr.; Sibeck, D. G.; Kanekal, S. G.; Kletzing, C.; Baker, D. N.; Wygant, J. R.</p> <p>2016-12-01</p> <p>Various physical processes can contribute to loss and acceleration of energetic <span class="hlt">electrons</span> in the Earth's radiation belts. In the range of 1 mHz to 10 Hz, ultra-low frequency (ULF) waves are known to cause significant changes in the energetic particle <span class="hlt">flux</span> in the radiation belts. On board the Van Allen Probes, the Relativistic <span class="hlt">Electron</span> Proton Telescope (REPT) measures the relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> in the outer radiation belts in the energy range from 1.8 MeV up to 20 MeV. We selected events that have significant <span class="hlt">electron</span> <span class="hlt">flux</span> dropouts, classified into two categories regarding the time elapsed between the outer radiation belt dropout and the refurbishing, namely events that time scale had taken (i) a few hours and, (ii) some days. This work aims to investigate the presence of ULF waves using the radial and azimuthal magnetic and electric field components recorded by the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS). The evaluation of the power spectral density of those components unravels the poloidal and toroidal characteristc of the rapid compressional waves. We discuss how these modes can contribute to modifications of the relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> considering the (i) and (ii) cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JPhCS.136d2093T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JPhCS.136d2093T"><span>Study of the <span class="hlt">electronic</span> structure of Ce-based heavy-fermion systems exposed to the low-energy neutrino dense <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trapeznikov, V. A.; Shabanova, I. N.; Murin, A. V.</p> <p>2008-11-01</p> <p>The class of compounds based on f-elements (Ce) attracts great attention because of their unusual properties. They are characterized by a heavy-fermion state, which occurs in them under certain external actions. Heavy-fermion materials have unique properties. The objective of the work is the investigation of a change in the <span class="hlt">electronic</span> structure in a number of Ce-based systems under the action of a dense neutrino <span class="hlt">flux</span> in order to develop the technology for the essential change of material properties. To increase the density of the neutrino <span class="hlt">flux</span> by several orders of magnitude, the phenomenon of diffraction is used. The investigation of the <span class="hlt">electronic</span> structure of Ce-based systems on the <span class="hlt">electron</span> magnetic spectrometer using the x-ray <span class="hlt">electron</span> method and the calculations of the density of states at different temperatures has shown the decrease in the intensity of the localized resonance maximum near Fermi level with increasing temperature.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22596578','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22596578"><span>Measurement of effect of <span class="hlt">electron</span> cyclotron heating in a tandem mirror plasma using a semiconductor detector array and an electrostatic energy analyzer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Minami, R. Imai, T.; Kariya, T.; Numakura, T.; Uehara, M.; Tsumura, K.; Ebashi, Y.; Kajino, S.; Endo, Y.; Nakashima, Y.</p> <p>2016-11-15</p> <p>Temporally and spatially resolved soft x-ray and end-loss-<span class="hlt">electron</span> analyses of the <span class="hlt">electron</span> cyclotron heated plasmas are carried out by using a semiconductor detector array and an electrostatic energy analyzer in the GAMMA 10 tandem mirror. The <span class="hlt">flux</span> and the energy spectrum of the end loss <span class="hlt">electrons</span> are measured by a multi-grid energy analyzer. Recently, the <span class="hlt">electron</span> cyclotron heating power modulation experiments have been started in order to generate and control the <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> and to make the edge localized mode-like intermittent heat load pattern for the divertor simulation studies by the use of these detectors for <span class="hlt">electron</span> properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87kE306M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87kE306M"><span>Measurement of effect of <span class="hlt">electron</span> cyclotron heating in a tandem mirror plasma using a semiconductor detector array and an electrostatic energy analyzer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minami, R.; Imai, T.; Kariya, T.; Numakura, T.; Uehara, M.; Tsumura, K.; Ebashi, Y.; Kajino, S.; Endo, Y.; Nakashima, Y.</p> <p>2016-11-01</p> <p>Temporally and spatially resolved soft x-ray and end-loss-<span class="hlt">electron</span> analyses of the <span class="hlt">electron</span> cyclotron heated plasmas are carried out by using a semiconductor detector array and an electrostatic energy analyzer in the GAMMA 10 tandem mirror. The <span class="hlt">flux</span> and the energy spectrum of the end loss <span class="hlt">electrons</span> are measured by a multi-grid energy analyzer. Recently, the <span class="hlt">electron</span> cyclotron heating power modulation experiments have been started in order to generate and control the <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> and to make the edge localized mode-like intermittent heat load pattern for the divertor simulation studies by the use of these detectors for <span class="hlt">electron</span> properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25036824','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25036824"><span>O2-dependent large <span class="hlt">electron</span> flow functioned as an <span class="hlt">electron</span> sink, replacing the steady-state <span class="hlt">electron</span> <span class="hlt">flux</span> in photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, but not in the cyanobacterium Synechococcus sp. PCC 7942.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hayashi, Ryosuke; Shimakawa, Ginga; Shaku, Keiichiro; Shimizu, Satoko; Akimoto, Seiji; Yamamoto, Hiroshi; Amako, Katsumi; Sugimoto, Toshio; Tamoi, Masahiro; Makino, Amane; Miyake, Chikahiro</p> <p>2014-01-01</p> <p>To determine whether alternative <span class="hlt">electron</span> flow (AEF) can replace the photosynthetic <span class="hlt">electron</span> flow in cyanobacteria, we used an open O2-electrode system to monitor O2-exchange over a long period. In air-grown Synechocystis sp. PCC 6803 (S. 6803(WT)), the quantum yield of PSII, Y(II), held even after photosynthesis was suppressed by CO2 shortage. The S. 6803 mutant, deficient in flavodiiron (FLV) proteins 1 and 3, showed the same phenotype as S. 6803(WT). In contrast, Y(II) decreased in Synechococcus sp. PCC 7942 (S. 7942). These results suggest that AEF functioned as the Y(II) in S. 6803 and replaced the photosynthetic <span class="hlt">electron</span> <span class="hlt">flux</span>. In contrast, the activity of AEF in S. 7942 was lower. The affinity of AEF for O2 in S. 6803 did not correspond to those of FLVs in bacteria or terminal oxidases in respiration. AEF might be driven by photorespiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990saea.conf.....B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990saea.conf.....B"><span>The development of advanced cooling methods for high-power <span class="hlt">electronics</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bland, T. J.; Ciaccio, M. P.; Downing, R. S.; Smith, W. G.</p> <p>1990-10-01</p> <p>Consideration is given to various technologies developed to meet the difficult cooling requirements of high-density power <span class="hlt">electronics</span> equipment for the aerospace industry. Topics discussed include liquid impingement cooling, compact high-density cooler, integrally cooled semiconductor, <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> cold plane, immersion cooling, modular reflux cooler, and forced-flow two-phase cooling systems. It is concluded that the new technologies are capable of providing the temperature control necessary to maintain desired <span class="hlt">electronic</span> reliabilities using high-conductance cooling approaches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7097371','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7097371"><span>Workshop on <span class="hlt">high</span> <span class="hlt">heat</span> load x-ray optics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1990-01-01</p> <p>A workshop on <span class="hlt">High</span> <span class="hlt">Heat</span> Load X-Ray Optics'' was held at Argonne National Laboratory on August 3--5, 1989. The object of this workshop was to discuss recent advances in the art of cooling x-ray optics subject to <span class="hlt">high</span> <span class="hlt">heat</span> loads from synchrotron beams. The cooling of the first optical element in the intense photon beams that will be produced in the next generation of synchrotron sources is recognized as one of the major challenges that must be faced before one will be able to use these very intense beams in future synchrotron experiments. Considerable advances have been made in this art during the last few years, but much work remains to be done before the heating problem can be said to be completely solved. Special emphasis was placed on recent cooling experiments and detailed finite element'' and finite difference'' calculations comparing experiment with theory and extending theory to optimize performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7158993','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7158993"><span>Method of preparing a <span class="hlt">high</span> <span class="hlt">heating</span> value fuel product</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Somerville, R.; Fan, L.T.</p> <p>1989-10-24</p> <p>This patent describes a method of preparing a <span class="hlt">high</span> <span class="hlt">heating</span> value fuel product. The method comprising the steps of: blending a <span class="hlt">high</span> <span class="hlt">heating</span> value waste material with a cellulosic material; mixing an organic reagent to the blended mixture of the waste material and the cellulosic material, the organic reagent being a mixture having a 4-15 weight percent of a chemical selected from the group consisting of: triethylene, glycol, diethylene glycol, and glycerin propylene glycol; introducing a pozzolanic agent to the blended mixture for controlling the rate of solidification; and forming the blended mixture into a form suitable for handling. Also described is the same method with the mixture of the organic reagent further comprising: a 20-32 weight percent calcium chloride solution. Another method of preparing a fuel product is also described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Ge%26Ae..57....8M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Ge%26Ae..57....8M"><span>Prediction of relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> in the Earth's outer radiation belt at geostationary orbit by adaptive methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myagkova, I. N.; Dolenko, S. A.; Efitorov, A. O.; Shirokii, V. R.; Sentemova, N. S.</p> <p>2017-01-01</p> <p>The paper investigates the possibilities of the prediction of the time series of the <span class="hlt">flux</span> of relativistic <span class="hlt">electrons</span> in the Earth's outer radiation belt by parameters of the solar wind and the interplanetary magnetic field measured at the libration point and by the values of the geomagnetic indices. Different adaptive methods are used (namely, artificial neural networks, group method of data handling, and projection to latent structures). The comparison of quality indicators of predictions with a horizon of 1-12 h between each other and with the trivial model prediction has shown that the best result is obtained for the average value of the responses of three neural networks that have been trained with different sets of initial weights. The prediction result of the group method of data handling is close to the result of neural networks, and the projection to latent structures is much worse. It is shown that an increase in the prediction horizon from 1 to 12 h reduces its quality but not dramatically, which makes it possible to use these methods for medium-term prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/940139','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/940139"><span>Fast Ignition relevant study of the <span class="hlt">flux</span> of high intensity laser generated <span class="hlt">electrons</span> via a hollow cone into a laser-imploded plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Key, M; Adam, J; Akli, K; Borgheshi, M; Chen, M; Evans, R; Freeman, R; Hatchett, S; Hill, J; Heron, A; King, J; Lancaster, K; Mackinnon, A; Norreys, P; Phillips, T; Romagnani, L; Snavely, R; Stephens, R; Stoeckl, C</p> <p>2005-10-11</p> <p>An integrated experiment relevant to fast ignition is described. A Cu doped CD spherical shell target is imploded around an inserted hollow Au cone by a six beam 600J, 1ns laser to a peak density of 4gcm{sup -3} and a diameter of 100 {micro}m. A 10 ps, 20TW laser pulse is focused into the cone at the time of peak compression. The <span class="hlt">flux</span> of high-energy <span class="hlt">electrons</span> through the imploded material is determined from the yield of Cu K{alpha} fluorescence by comparison with a Monte Carlo model and is estimated to carry 15% of the laser energy. Collisional and Ohmic heating are modeled. An <span class="hlt">electron</span> spectrometer shows significantly greater reduction of the transmitted <span class="hlt">electron</span> <span class="hlt">flux</span> than is due to binary collisions and Ohmic potential. Enhanced scattering by instability-induced magnetic fields is suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26831831','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26831831"><span>Persistent current in a correlated quantum ring with <span class="hlt">electron</span>-phonon interaction in the presence of Rashba interaction and Aharonov-Bohm <span class="hlt">flux</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Monisha, P J; Sankar, I V; Sil, Shreekantha; Chatterjee, Ashok</p> <p>2016-02-01</p> <p>Persistent current in a correlated quantum ring threaded by an Aharonov-Bohm <span class="hlt">flux</span> is studied in the presence of <span class="hlt">electron</span>-phonon interactions and Rashba spin-orbit coupling. The quantum ring is modeled by the Holstein-Hubbard-Rashba Hamiltonian and the energy is calculated by performing the conventional Lang-Firsov transformation followed by the diagonalization of the effective Hamiltonian within a mean-field approximation. The effects of Aharonov-Bohm <span class="hlt">flux</span>, temperature, spin-orbit and <span class="hlt">electron</span>-phonon interactions on the persistent current are investigated. It is shown that the <span class="hlt">electron</span>-phonon interactions reduce the persistent current, while the Rashba coupling enhances it. It is also shown that temperature smoothens the persistent current curve. The effect of chemical potential on the persistent current is also studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735522','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735522"><span>Persistent current in a correlated quantum ring with <span class="hlt">electron</span>-phonon interaction in the presence of Rashba interaction and Aharonov-Bohm <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Monisha, P. J.; Sankar, I. V.; Sil, Shreekantha; Chatterjee, Ashok</p> <p>2016-01-01</p> <p>Persistent current in a correlated quantum ring threaded by an Aharonov-Bohm <span class="hlt">flux</span> is studied in the presence of <span class="hlt">electron</span>-phonon interactions and Rashba spin-orbit coupling. The quantum ring is modeled by the Holstein-Hubbard-Rashba Hamiltonian and the energy is calculated by performing the conventional Lang-Firsov transformation followed by the diagonalization of the effective Hamiltonian within a mean-field approximation. The effects of Aharonov-Bohm <span class="hlt">flux</span>, temperature, spin-orbit and <span class="hlt">electron</span>-phonon interactions on the persistent current are investigated. It is shown that the <span class="hlt">electron</span>-phonon interactions reduce the persistent current, while the Rashba coupling enhances it. It is also shown that temperature smoothens the persistent current curve. The effect of chemical potential on the persistent current is also studied. PMID:26831831</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870007469','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870007469"><span>Conventionally cast and forged copper alloy for <span class="hlt">high-heat-flux</span> thrust chambers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kazaroff, John M.; Repas, George A.</p> <p>1987-01-01</p> <p>The combustion chamber liner of the space shuttle main engine is made of NARloy-Z, a copper-silver-zirconium alloy. This alloy was produced by vacuum melting and vacuum centrifugal casting; a production method that is currently now available. Using conventional melting, casting, and forging methods, NASA has produced an alloy of the same composition called NASA-Z. This report compares the composition, microstructure, tensile properties, low-cycle fatigue life, and hot-firing life of these two materials. The results show that the materials have similar characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/270446','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/270446"><span>Fatigue behavior of copper and selected copper alloys for <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leedy, K.D.; Stubbins, J.F.; Singh, B.N.; Garner, F.A.</p> <p>1996-04-01</p> <p>The room temperature fatigue behavior of standard and subsize specimens was examined for five copper alloys: OFHC Cu, two CuNiBe alloys, a CuCrZr alloy, and a Cu-Al{sub 2}O{sub 3} alloy. Fatigue tests were run in strain control to failure. In addition to establishing failure lives, the stress amplitudes were monitored as a function of numbers of accrued cycles. The results indicate that the alloys with high initial yield strengths provide the best fatigue response over the range of failure lives examined in the present study: N{sub f} = 10{sup 3} to 10{sup 6}. In fact, the fatigue performance of the best alloys is dominated by the elastic portion of the strain range, as would be expected from the correlation of performance with yield properties. The alumina strengthened alloy and the two CuNiBe alloys show the best overall performance of the group examined here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900007595','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900007595"><span>Thermal modelling of various thermal barrier coatings in a <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> rocket engine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nesbitt, James A.</p> <p>1989-01-01</p> <p>Traditional Air Plasma Sprayed (APS) ZrO2-Y2O3 Thermal Barrier Coatings (TBC's) and Low Pressure Plasma Sprayed (LPPS) ZrO2-Y2O3/Ni-Cr-Al-Y cermet coatings were tested in a H2/O2 rocked engine. The traditional ZrO2-Y2O3 (TBC's) showed considerable metal temperature reductions during testing in the hydrogen-rich environment. A thermal model was developed to predict the thermal response of the tubes with the various coatings. Good agreement was observed between predicted temperatures and measured temperatures at the inner wall of the tube and in the metal near the coating/metal interface. The thermal model was also used to examine the effect of the differences in the reported values of the thermal conductivity of plasma sprayed ZrO2-Y2O3 ceramic coatings, the effect of 100 micron (0.004 in.) thick metallic bond coat, the effect of tangential heat transfer around the tube, and the effect or radiation from the surface of the ceramic coating. It was shown that for the short duration testing in the rocket engine, the most important of these considerations was the effect of the uncertainty in the thermal conductivity of temperatures (greater than 100 C) predicted in the tube. The thermal model was also used to predict the thermal response of the coated rod in order to quantify the difference in the metal temperatures between the two substrate geometries and to explain the previously-observed increased life of coatings on rods over that on tubes. A thermal model was also developed to predict heat transfer to the leading edge of High Pressure Fuel Turbopump (HPFTP) blades during start-up of the space shuttle main engines. The ability of various TBC's to reduce metal temperatures during the two thermal excursions occurring on start-up was predicted. Temperature reductions of 150 to 470 C were predicted for 165 micron (0.0065 in.) coatings for the greater of the two thermal excursions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920049775&hterms=engine+thermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dengine%2Bthermal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920049775&hterms=engine+thermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dengine%2Bthermal"><span>Thermal response of various thermal barrier coatings in a <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> rocket engine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nesbitt, J. A.</p> <p>1990-01-01</p> <p>Traditional APS ZrO2-Y2O3 thermal barrier coatings (TBCs) formed by air plasma spraying and low pressure and air plasma sprayed ZrO2-Y2O3/NiCrAlY cermet coatings were tested in an H2-O2 rocket engine. The test cycle was approximately 1.2 s at 1400 C in a hydrogen-rich environment. During testing, the maximum metal temperature without a coating was 1310 C. The traditional ZrO2-Y2O3 TBCs with a 100-125 micron thick ceramic layer reduced the maximum metal temperature by approximately 350 C. Increasing the ceramic layer thickness to 200-225 microns resulted in an additional metal temperature reduction of 100 C. However, the cermet coatings, consisting of a ceramic and metal mixture, exhibited a much lower thermal protection capability by reducing the maximum metal temperature by approximately 100 C. It was also found that the surface roughness of the traditional TBCs had little effect on the thermal response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA469754','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA469754"><span>Electromagnetic Control of <span class="hlt">High</span> <span class="hlt">Heat-Flux</span> Spray Impingement Boiling Under Microgravity Conditions</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2007-03-01</p> <p>research. Further increases in heat transfer performance are likely to result from a better understanding of the relevant microphysics and better electrode... understanding of the relevant microphysics and better electrode designs. Experimental results have been used to estimate the time scales for various...Pentium 4 class single processor personal computers that were used. In addition, significant gaps in physical understanding concerning the interaction of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA266086','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA266086"><span>Boiling Heat-Transfer Processes and Their Application in the Cooling of <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Devices</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1993-06-01</p> <p>requires an understanding of the parameters that affect the cooling processes and the determination of the limiting point where the surface fails due...application requires an understanding of the parameters that affect the cooling processes and the determination of the limiting point * where the surface fails...data points within ± 25 percent. 47 AEDC-TR-93-3 (41) Gambill and Lienhard (Ref. 231) presented an interesting semiempirical approach to determining a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050198964','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050198964"><span>Actively Cooled Ceramic Matrix Composite Concepts for <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eckel, Andrew J.; Jaskowiak, Martha H.; Dickens, Kevin</p> <p>2004-01-01</p> <p>High temperature composite heat exchangers are an enabling technology for a number of aeropropulsion applications. They offer the potential for mass reductions of greater than fifty percent over traditional metallics designs and enable vehicle and engine designs. Since they offer the ability to operate at significantly higher operating temperatures, they facilitate operation at reduced coolant flows and make possible temporary uncooled operation in temperature regimes, such as experienced during vehicle reentry, where traditional heat exchangers require coolant flow. This reduction in coolant requirements can translate into enhanced range or system payload. A brief review of the approaches, challenges and test results are presented, along with a status of recent government-funded projects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930015572','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930015572"><span>Development of dispersion-strengthened XD (trademark) Cu alloys for <span class="hlt">high</span> <span class="hlt">heat-flux</span> applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kumar, K. Sharvan</p> <p>1993-01-01</p> <p>In a previous effort sponsored by NASA LeRC, the XD(trademark) process was used to produce ZrB2 particulate reinforcements in Cu and the resulting extruded material was microstructurally characterized and evaluated in tension over a range of temperatures. A problem that was encountered in that study was microstructural inhomogeneity resulting from the frequent presence of 'ZrB2 agglomerates' that were several microns in size. The presence of these agglomerates was attributed to improper mixing of powders in the green compact used in the XD process for elemental boron powder segregation. In this program, several milling parameters were examined in an effort to optimize this processing step; two levels of ZrB2 reinforcements were considered (7 vol. percent and 15 vol. percent). Microstructures of the reacted powder mass were examined to verify the absence of these agglomerates. Larger bathes of powder were then mixed, reacted, machined to size, canned, and extruded. The microstructure and tensile properties of these extrusions were examined, and the measured properties were correlated with the observed microstructure. Large unreacted or partially reacted Zr particles were present. These particles affected the mechanical properties deleteriously, and their presence is attributed to insufficient heat of reaction during XD synthesis. Alternate processing routes are recommended.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900019336','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900019336"><span>Thermal analysis of thermal barrier coatings in a <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> environment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nesbitt, James A.; Brindley, William J.</p> <p>1988-01-01</p> <p>Gas temperatures and pressures were measured around the second test position in the H2/O2 rocket engine at NASA-Lewis. Measured gas temperatures generally varied from 1210 to 1390 C. Measured pressures were in good agreement with other studies for throat tubes in a square chamber rocket engine. Heat transfer coefficients were measured at 90 and 180 degrees from the stagnation point and resulted in values of 27.5 and 8.5 kW/sq m C, respectively. A thermal model was developed to predict temperatures in bare and coated tubes and rods. Agreement between measured and predicted temperatures below the surface of a bare Mar-M 246 tube was very good for most of the heat up and cool down period. Predicted temperatures were significantly below measured temperatures for the coated tubes. A thermal model to simulate heat transfer to the leading edge of an HPFTP blade was developed and showed that TBCs can significantly dampen the thermal transient which occurs in the HPFTP during the startup of the SSME.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JNuM..417..643C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JNuM..417..643C"><span>Characterization and damaging law of CFC for <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> actively cooled plasma facing components</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chevet, G.; Martin, E.; Boscary, J.; Camus, G.; Herb, V.; Schlosser, J.; Escourbiac, F.; Missirlian, M.</p> <p>2011-10-01</p> <p>The carbon fiber reinforced carbon composite (CFC) Sepcarb N11 has been used in the Tore Supra (TS) tokamak (Cadarache, France) as armour material for the plasma facing components. For the fabrication of the Wendelstein 7-X (W7-X) divertor (Greifswald, Germany), the NB31 material was chosen. For the fabrication of the ITER divertor, two potential CFC candidates are the NB31 and NB41 materials. In the case of Tore Supra, defects such as microcracks or debonding were found at the interface between CFC tile and copper heat sink. A mechanical characterization of the behaviour of N11 and NB31 was undertaken, allowing the identification of a damage model and finite element calculations both for flat tiles (TS and W7-X) and monoblock (ITER) armours. The mechanical responses of these CFC materials were found almost linear under on-axis tensile tests but highly nonlinear under shear tests or off-axis tensile tests. As a consequence, damage develops within the high shear-stress zones.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA467838','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA467838"><span>Experimental and Numerical Investigations of RP-2 Under <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2007-05-01</p> <p>well-known Dittus-Boelter and Sieder -Tate correlations and the NASA/GRC correlation of Stiegemeier et. al is presented for Reynolds numbers between...Boelter and Sieder -Tate correlations and the NASA/GRC correlation of Stiegemeier et. al is presented for Reynolds numbers between 5,000-35,000...530 psi 165 ft/s, 1720 psi Nu, Dittus-Boelter Nu, Sieder -Tate Nu, NASA-GRC 2002 Figure 3. Comparison of experimental data with existing heat</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000021159','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000021159"><span>Monolithic Cu-Cr-Nb Alloys for High Temperature, <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ellis, David L.; Locci, Ivan E.; Michal, Gary M.; Humphrey, Derek M.</p> <p>1999-01-01</p> <p>Work during the prior four years of this grant has resulted in significant advances in the development of Cu-8 Cr4 Nb and related Cu-Cr-Nb alloys. The alloys are nearing commercial use in the Reusable Launch Vehicle (RLV) where they are candidate materials for the thrust cell liners of the aerospike engines being developed by Rocketdyne. During the fifth and final year of the grant, it is proposed to complete development of the design level database of mechanical and thermophysical properties and transfer it to NASA Glenn Research Center and Rocketdyne. The database development work will be divided into three main areas: Thermophysical Database Augmentation, Mechanical Testing and Metallography and Fractography. In addition to the database development, work will continue that is focussed on the production of alternatives to the powder metallurgy alloys currently used. Exploration of alternative alloys will be aimed at both the development of lower cost materials and higher performance materials. A key element of this effort will be the use of Thermo-Calc software to survey the solubility behavior of a wide range of alloying elements in a copper matrix. The ultimate goals would be to define suitable alloy compositions and processing routes to produce thin sheets of the material at either a lower cost, or, with improved mechanical and thermal properties compared to the current Cu-Cr-Nb powder metallurgy alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JMiMi..15..362X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JMiMi..15..362X"><span>Microscale boiling heat transfer in a micro-timescale at <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Jinliang; Gan, Yunhua; Zhang, Dacheng; Li, Xiuhan</p> <p>2005-02-01</p> <p>Microscale boiling heat transfer experiments were performed using acetone as the working fluid in ten parallel silicon microchannels with hydraulic diameters of 155.4 µm. An infrared radiator image system is used for the chip temperature measurements, while an optical system combining a microscope and a high-speed camera is used for transient flow pattern identification. By covering the present data range it is found that all microchannels repeat the transient flow patterns in a timescale of milliseconds while the fluid pressures/temperatures are stable. A full cycle can be subdivided into three substages: liquid refilling stage, bubble nucleation, growth and coalescence stage, and transient annular flow stage. Correspondingly four flow patterns are identified. Paired or triplet bubbles are observed to be nucleated and grow up simultaneously in, or very close to, the channel corners at the same cross section. The nucleated bubbles experience several milliseconds of growth until coalescence takes place. Then a single liquid plug is separated into two parts, which are pushed out of the flow field view in less than 1 ms. In the transient annular flow stage, the liquid films that are drawn into the corners of the channel become less and less versus time. Once a partially or fully dried-out state is reached, all the microchannels are refilled with fresh liquid and a new cycle begins. The probabilities of each flow pattern occurring and the liquid refilling follow the statistical principle well. The measured chip temperatures are not uniform across the whole heating area, attributed to the uneven liquid refilling probabilities for different channels and the uneven possibilities that are immersed in the liquid for different heating regions. The chip temperatures display spatial variation behavior in the majority of the heating area, due to the liquid and vapor alternatively passing through the microchannels. To the authors' knowledge, some of the above experimental findings have not been previously reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040020114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040020114"><span>High Conductivity Materials for <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Applications in Space Propulsion Systems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nathal, M. V.; Ellis, D. L.; Loewenthal, W. S.; Raj, S. V.; Thomas-Ogbuji, L. U.; Ghosn, J.; Greenbauer-Seng, L. A.; Gayda, J.; Barrett, C. A.</p> <p>2003-01-01</p> <p>GRCop-84 is a new copper base alloy with an excellent combination of strength and conductivity and has been developed to the point that it is a strong candidate for near term rocket engine applications. This work sought to establish the feasibility of new alloys with capabilities beyond GRCop-84. The use of coatings as environmental and thermal barriers adds further capability into the Copper base structure. Finally, Nickel-Aluminum based systems have also been explored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790012226','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790012226"><span><span class="hlt">High</span> <span class="hlt">heat</span> <span class="hlt">flux</span> actively cooled honeycomb sandwich structural panel for a hypersonic aircraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koch, L. C.; Pagel, L. L.</p> <p>1978-01-01</p> <p>The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA473362','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA473362"><span>Design and Analysis of Alternative <span class="hlt">High</span> <span class="hlt">Heat</span> <span class="hlt">Flux</span> Sources for Materials Fire Testing - PREPRINT</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2007-10-18</p> <p>crash aviation fires (Figure 1)2. The latest generation of military and commercial aircraft is constructed with large quantities of carbon fiber composites . In...parts for the original apparatus.3 The latest generation of military and commercial aircraft is constructed with large quantities of carbon fiber composites . In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/432843','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/432843"><span>Contact-cooled U-monochromators for <span class="hlt">high</span> <span class="hlt">heat</span> load x-ray beamlines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Khounsary, A.; Yun, W.; Trakhtenberg, E.; Xu, S.; Assoufid, L.; Lee, W.K.</p> <p>1996-12-31</p> <p>This paper describes the design, expected performance, and preliminary test results of a contact-cooled monochromator for use on <span class="hlt">high</span> <span class="hlt">heat</span> load x-ray beamlines. The monochromator has a cross section in the shape of the letter U. This monochromator should be suitable for handing heat <span class="hlt">fluxes</span> up to 5 W/square millimeter. As such, for the present application, it is compatible with the best internally cooled crystal monochromators. There are three key features in the design of this monochromator. First, it is contact cooled, thereby eliminating fabrication of cooling channels, bonding, and undesirable strains in the monochromator due to coolant-manifold-to-crystal-interface. Second, by illuminating the entire length of the crystal and extracting the central part of the reflected beam, sharp slope changes in the beam profile and thus slope errors are avoided. Last, by appropriate cooling of the crystal, tangential slope error can be substantially reduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SpWea..14...22B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SpWea..14...22B"><span>Comparative analysis of NOAA REFM and SNB3GEO tools for the forecast of the <span class="hlt">fluxes</span> of high-energy <span class="hlt">electrons</span> at GEO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balikhin, M. A.; Rodriguez, J. V.; Boynton, R. J.; Walker, S. N.; Aryan, H.; Sibeck, D. G.; Billings, S. A.</p> <p>2016-01-01</p> <p>Reliable forecasts of relativistic <span class="hlt">electrons</span> at geostationary orbit (GEO) are important for the mitigation of their hazardous effects on spacecraft at GEO. For a number of years the Space Weather Prediction Center at NOAA has provided advanced online forecasts of the fluence of <span class="hlt">electrons</span> with energy >2 MeV at GEO using the Relativistic <span class="hlt">Electron</span> Forecast Model (REFM). The REFM forecasts are based on real-time solar wind speed observations at L1. The high reliability of this forecasting tool serves as a benchmark for the assessment of other forecasting tools. Since 2012 the Sheffield SNB3GEO model has been operating online, providing a 24 h ahead forecast of the same <span class="hlt">fluxes</span>. In addition to solar wind speed, the SNB3GEO forecasts use solar wind density and interplanetary magnetic field Bz observations at L1.The period of joint operation of both of these forecasts has been used to compare their accuracy. Daily averaged measurements of <span class="hlt">electron</span> <span class="hlt">fluxes</span> by GOES 13 have been used to estimate the prediction efficiency of both forecasting tools. To assess the reliability of both models to forecast infrequent events of very high <span class="hlt">fluxes</span>, the Heidke skill score was employed. The results obtained indicate that SNB3GEO provides a more accurate 1 day ahead forecast when compared to REFM. It is shown that the correction methodology utilized by REFM potentially can improve the SNB3GEO forecast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CosRe..55...72M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CosRe..55...72M"><span>Dynamics of <span class="hlt">electron</span> <span class="hlt">fluxes</span> in the slot between radiation belts in November-December 2014 according to data of the Vernov satellite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myagkova, I. N.; Svertilov, S. I.; Kovtyukh, A. S.; Bogomolov, V. V.; Bogomolov, A. V.; Panasyuk, M. I.; Sibiryakova, D. V.; Balan, E. V.</p> <p>2017-01-01</p> <p>The variations in the spatial structure and time in <span class="hlt">electron</span> <span class="hlt">fluxes</span> with E = 235-300 keV in the slot region (2 < L < 3) between the radiation belts in the period of November 1, 2014 through December 8, 2014 during weak and moderate geomagnetic disturbances ( Kp < 4, Dst >-60 nT) are analyzed based on the data of the RELEC complex on board the Vernov satellite (the height and inclination of the orbit are from 640 to 830 km and 98.4°, respectively). Irregular increases in the <span class="hlt">fluxes</span> of such <span class="hlt">electrons</span> and formation of a local maximum at L 2.2-3.0 were observed. It has been shown that the intensity of this maximum is inversely proportional to the L value and grows with an increase in the geomagnetic activity level. New features discovered for the first time in the dynamics of radiation belt <span class="hlt">electrons</span> manifest in the variations in the local structure and dynamics of <span class="hlt">fluxes</span> of subrelativistic <span class="hlt">electrons</span> in the slot region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E2014V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E2014V"><span>Comparative dynamics of relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> during two geomagnetic storms on 17-18 March and on 22-23 June 22-23 in 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vlasova, Natalia; Kalegaev, Vladimir; Beresneva, Evgeniya; Stanislav, Ganitskiy</p> <p>2016-07-01</p> <p>The role of solar wind in the outer Earth`s radiation belt dynamics is under consideration during the last decades. Unfortunately, the physical mechanisms that control the loss and acceleration of the magnetospheric relativistic <span class="hlt">electron</span> <span class="hlt">fluxes</span> are not evident until now. In this study we compared and contrasted some features of relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> dynamics during two largest geomagnetic storms in 2015 (17-18 March and 22-23 June) having the similar Dst-variations profiles and amplitudes (~200 nT). Analysis of experimental data from Van Allen Probes (RBSP), GOES, Electro, POES, Meteor satellites was combined with theoretical investigations on the base of the A2000 model of the magnetospheric magnetic field. Multipoint observations at GEO and LEO show the dramatic changes in the MeV <span class="hlt">electron</span> populations during the main phase of the magnetic storms. We found the solar wind and IMF variations responsible for large-scale magnetospheric current system changes that reveal themselves in the relativistic <span class="hlt">electron</span> <span class="hlt">flux</span> dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27642268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27642268"><span>Comparative analysis of NOAA REFM and SNB(3)GEO tools for the forecast of the <span class="hlt">fluxes</span> of high-energy <span class="hlt">electrons</span> at GEO.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Balikhin, M A; Rodriguez, J V; Boynton, R J; Walker, S N; Aryan, H; Sibeck, D G; Billings, S A</p> <p>2016-01-01</p> <p>Reliable forecasts of relativistic <span class="hlt">electrons</span> at geostationary orbit (GEO) are important for the mitigation of their hazardous effects on spacecraft at GEO. For a number of years the Space Weather Prediction Center at NOAA has provided advanced online forecasts of the fluence of <span class="hlt">electrons</span> with energy >2 MeV at GEO using the Relativistic <span class="hlt">Electron</span> Forecast Model (REFM). The REFM forecasts are based on real-time solar wind speed observations at L1. The high reliability of this forecasting tool serves as a benchmark for the assessment of other forecasting tools. Since 2012 the Sheffield SNB(3)GEO model has been operating online, providing a 24 h ahead forecast of the same <span class="hlt">fluxes</span>. In addition to solar wind speed, the SNB(3)GEO forecasts use solar wind density and interplanetary magnetic field Bz observations at L1.The period of joint operation of both of these forecasts has been used to compare their accuracy. Daily averaged measurements of <span class="hlt">electron</span> <span class="hlt">fluxes</span> by GOES 13 have been used to estimate the prediction efficiency of both forecasting tools. To assess the reliability of both models to forecast infrequent events of very high <span class="hlt">fluxes</span>, the Heidke skill score was employed. The results obtained indicate that SNB(3)GEO provides a more accurate 1 day ahead forecast when compared to REFM. It is shown that the correction methodology utilized by REFM potentially can improve the SNB(3)GEO forecast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003242&hterms=Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEnergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003242&hterms=Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEnergy"><span>Comparative Analysis of NOAA REFM and SNB3GEO Tools for the Forecast of the <span class="hlt">Fluxes</span> of High-Energy <span class="hlt">Electrons</span> at GEO</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Balikhin, M. A.; Rodriguez, J. V.; Boynton, R. J.; Walker, S. N.; Aryan, Homayon; Sibeck, D. G.; Billings, S. A.</p> <p>2016-01-01</p> <p>Reliable forecasts of relativistic <span class="hlt">electrons</span> at geostationary orbit (GEO) are important for the mitigation of their hazardous effects on spacecraft at GEO. For a number of years the Space Weather Prediction Center at NOAA has provided advanced online forecasts of the fluence of <span class="hlt">electrons</span> with energy >2 MeV at GEO using the Relativistic <span class="hlt">Electron</span> Forecast Model (REFM). The REFM forecasts are based on real-time solar wind speed observations at L1. The high reliability of this forecasting tool serves as a benchmark for the assessment of other forecasting tools. Since 2012 the Sheffield SNB3GEO model has been operating online, providing a 24 h ahead forecast of the same <span class="hlt">fluxes</span>. In addition to solar wind speed, the SNB3GEO forecasts use solar wind density and interplanetary magnetic field B(sub z) observations at L1. The period of joint operation of both of these forecasts has been used to compare their accuracy. Daily averaged measurements of <span class="hlt">electron</span> <span class="hlt">fluxes</span> by GOES 13 have been used to estimate the prediction efficiency of both forecasting tools. To assess the reliability of both models to forecast infrequent events of very high <span class="hlt">fluxes</span>, the Heidke skill score was employed. The results obtained indicate that SNB3GEO provides a more accurate 1 day ahead forecast when compared to REFM. It is shown that the correction methodology utilized by REFM potentially can improve the SNB3GEO forecast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/50533','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/50533"><span>Relationship between energy <span class="hlt">flux</span> Q and mean energy <E> of auroral <span class="hlt">electron</span> spectra based on radar data from the 1987 CEDAR Campaign at Sondre Stromfjord, Greenland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Strickland, D.J.; Hecht, J.H.; Christensen, A.B.; Kelly, J.</p> <p>1994-10-01</p> <p>The incoherent scatter radar at Sondre Stromfjord, Greenland, measured <span class="hlt">electron</span> density profiles from 90 to 500 km during four auroral events over a 3-hour period on February 28, 1987. The profiles were obtained with the radar pointed along the magnetic field near zenith at 15-s intervals. Under the assumption that proton/H atom precipitation was unimportant during these events a representation of the incident <span class="hlt">electron</span> <span class="hlt">flux</span> was obtained by fitting calculated profiles with measured profiles in the vicinity of their peaks (lower E region). Maxwellian and Gaussian <span class="hlt">electron</span> distributions with high- and low-energy tails were used to generate the calculated profiles. The distributions were specified in terms of average energy <E> and energy <span class="hlt">flux</span> Q. The authors find that they can clearly distinguish between profiles that result from a Maxwellian incident <span class="hlt">electron</span> spectrum and those that result from a Gaussian spectrum. Interpreting Gaussian and Maxwellian spectra as representative of discrete and diffuse aurora, respectively, the measurements indicated good correlation between <E> and Q for discrete aurora, while essentially no correlation was observed for diffuse aurora. This is consistent with current understanding that discrete auroras are produced by <span class="hlt">electrons</span> accelerated by magnetic field-aligned potential drops whereas diffuse auroras are produced by pitch angle diffusion of plasma sheet <span class="hlt">electrons</span> into the loss cone. 27 refs., 8 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930038312&hterms=thin+film+thermocouple&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dthin%2Bfilm%2Bthermocouple','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930038312&hterms=thin+film+thermocouple&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dthin%2Bfilm%2Bthermocouple"><span>Novel thin-film heat <span class="hlt">flux</span> sensors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bhatt, Hemanshu; Zeller, Mary; Will, Herbert</p> <p>1992-01-01</p> <p>A new and simpler design for thin-film heat <span class="hlt">flux</span> sensors for utilization in <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span> environments is presented. The design of these sensors consists of a planar differential thermopile made up of a number of thermocouple pairs arranged in a circular array, two different thermal resistance layers deposited on the inside and outside junctions of the thermopile and a high emissivity coating. This design has shown good potential for measuring heat <span class="hlt">fluxes</span> in severe environments of aerospace propulsion systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5138187','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5138187"><span>Melatonin Increases the Chilling Tolerance of Chloroplast in Cucumber Seedlings by Regulating Photosynthetic <span class="hlt">Electron</span> <span class="hlt">Flux</span> and the Ascorbate-Glutathione Cycle</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhao, Hailiang; Ye, Lin; Wang, Yuping; Zhou, Xiaoting; Yang, Junwei; Wang, Jiawei; Cao, Kai; Zou, Zhirong</p> <p>2016-01-01</p> <p>The aim of the study was to monitor the effects of exogenous melatonin on cucumber (Cucumis sativus L.) chloroplasts and explore the mechanisms through which it mitigates chilling stress. Under chilling stress, chloroplast structure was seriously damaged as a result of over-accumulation of reactive oxygen species (ROS), as evidenced by the high levels of superoxide anion (O2−) and hydrogen peroxide (H2O2). However, pretreatment with 200 μM melatonin effectively mitigated this by suppressing the levels of ROS in chloroplasts. On the one hand, melatonin enhanced the scavenging ability of ROS by stimulating the ascorbate–glutathione (AsA–GSH) cycle in chloroplasts. The application of melatonin led to high levels of AsA and GSH, and increased the activity of total superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) dehydroascorbate reductase (DHAR, EC 1.5.5.1), glutathione reductase (GR, EC1.6.4.2) in the AsA–GSH cycle. On the other hand, melatonin lessened the production of ROS in chloroplasts by balancing the distribution of photosynthetic <span class="hlt">electron</span> <span class="hlt">flux</span>. Melatonin helped maintain a high level of <span class="hlt">electron</span> <span class="hlt">flux</span> in the PCR cycle [Je(PCR)] and in the PCO cycle [Je(PCO)], and suppressed the O2-dependent alternative <span class="hlt">electron</span> <span class="hlt">flux</span> Ja(O2-dependent) which is one important ROS source. Results indicate that melatonin increased the chilling tolerance of chloroplast in cucumber seedlings by accelerating the AsA–GSH cycle to enhance ROS scavenging ability and by balancing the distribution of photosynthetic <span class="hlt">electron</span> <span class="hlt">flux</span> so as to suppress ROS production. PMID:27999581</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016FrMat...3...33F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016FrMat...3...33F"><span>Advances on Sensitive <span class="hlt">Electron</span>-injection based Cameras for Low-<span class="hlt">Flux</span>, Short-Wave-Infrared Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fathipour, Vala; Bonakdar, Alireza; Mohseni, Hooman</p> <p>2016-08-01</p> <p>Short-wave infrared (SWIR) photon detection has become an essential technology in the modern world. Sensitive SWIR detector arrays with high pixel density, low noise levels and high signal-to-noise-ratios are highly desirable for a variety of applications including biophotonics, light detection and ranging, optical tomography, and astronomical imaging. As such many efforts in infrared detector research are directed towards improving the performance of the photon detectors operating in this wavelength range. We review the history, principle of operation, present status and possible future developments of a sensitive SWIR detector technology, which has demonstrated to be one of the most promising paths to high pixel density focal plane arrays for low <span class="hlt">flux</span> applications. The so-called <span class="hlt">electron</span>-injection (EI) detector was demonstrated for the first time (in 2007). It offers an overall system-level sensitivity enhancement compared to the p-i-n diode due to a stable internal avalanche-free gain. The amplification method is inherently low noise, and devices exhibit an excess noise of unity. The detector operates in linear-mode and requires only bias voltage of a few volts. The stable detector characteristics, makes formation of high yield large-format, and high pixel density focal plane arrays less challenging compared to other detector technologies such as avalanche photodetectors. Detector is based on the mature InP material system (InP/InAlAs/GaAsSb/InGaAs), and has a cutoff wavelength of 1700 nm. It takes advantage of a unique three-dimensional geometry and combines the efficiency of a large absorbing volume with the sensitivity of a low-dimensional switch (injector) to sense and amplify signals. Current devices provide high-speed response ~ 5 ns rise time, and low jitter ~ 12 ps at room temperature. The internal dark current density is ~ 1 μA/cm2 at room temperature decreasing to 0.1 nA/cm2 at 160 K. EI detectors have been designed, fabricated, and tested during two</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16592185','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16592185"><span>Geographical coincidence of <span class="hlt">high</span> <span class="hlt">heat</span> flow, high seismicity, and upwelling, with hydrocarbon deposits, phosphorites, evaporites, and uranium ores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Libby, L M; Libby, W F</p> <p>1974-10-01</p> <p>Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span>, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10(-4) of the total of buried biogenic carbon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=434300','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=434300"><span>Geographical Coincidence of <span class="hlt">High</span> <span class="hlt">Heat</span> Flow, High Seismicity, and Upwelling, with Hydrocarbon Deposits, Phosphorites, Evaporites, and Uranium Ores</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Libby, L. M.; Libby, W. F.</p> <p>1974-01-01</p> <p>Oil deposits occur in deep sediments, and appear to be organic matter that has been transformed through the action of geothermal heat and pressure. Deep sediments, rich in biological remains, are created by ocean upwelling, caused in part by high geothermal heat flow through the sea bottom. Such regions correlate with enhanced seismic activity. We look for correlations of seismicity, <span class="hlt">high</span> <span class="hlt">heat</span> <span class="hlt">flux</span>, petroleum, uranium, phosphates, and salts, deposited from abundant plant life. These may be useful in discovering more petroleum and coal. We estimate that the known world reserves of petroleum and coal are about 10-4 of the total of buried biogenic carbon. Images PMID:16592185</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PSST...23b5002D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PSST...23b5002D"><span>Time-resolved ion <span class="hlt">flux</span>, <span class="hlt">electron</span> temperature and plasma density measurements in a pulsed Ar plasma using a capacitively coupled planar probe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Darnon, Maxime; Cunge, Gilles; Braithwaite, Nicholas St. J.</p> <p>2014-04-01</p> <p>The resurgence of industrial interest in pulsed radiofrequency plasmas for etching applications highlights the fact that these plasmas are much less well characterized than their continuous wave counterparts. A capacitively coupled planar probe is used to determine the time variations of the ion <span class="hlt">flux</span>, <span class="hlt">electron</span> temperature (of the high-energy tail of the <span class="hlt">electron</span> energy distribution function) and plasma density. For a pulsing frequency of 1 kHz or higher, the plasma never reaches a steady state during the on-time and is not fully extinguished during the off-time. The drop of plasma density during the off-time leads to an overshoot in the <span class="hlt">electron</span> temperature at the beginning of each pulse, particularly at low frequencies, in good agreement with modeling results from the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhST..145a4079H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhST..145a4079H"><span>Micro-chemical analysis of <span class="hlt">high</span> <span class="hlt">heat</span> loaded CFC-Cu interfaces from Tore Supra and Wendelstein 7-X</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Höschen, T.; Linsmeier, Ch; Greuner, H.; Missirlian, M.</p> <p>2011-12-01</p> <p>A comparison of <span class="hlt">high-heat-flux</span> tested carbon-fiber reinforced carbon (CFC)/Cu materials of Tore Supra and Wendelstein 7-X plasma-facing components is made in order to understand the different fatigue behavior of the bonding interfaces, in particular for the Tore Supra materials. The elemental distribution around the bonding layer and the chemical composition of the active element titanium are characterized by secondary ion mass spectrometry and x-ray photoelectron spectroscopy. The results show that the improved bonding of the Wendelstein 7-X target elements compared to the Tore Supra pump limiter elements is due to a modified silicon and titanium distribution at the bonding interface. However, the difference in fatigue behavior between the two Tore Supra components cannot be attributed to the bonding interface, since the elemental distribution and chemistry of these components are identical and no degradation is observed after an extended heat <span class="hlt">flux</span> exposure.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21476102','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21476102"><span>High energy <span class="hlt">electron</span> <span class="hlt">fluxes</span> in dc-augmented capacitively coupled plasmas. II. Effects on twisting in high aspect ratio etching of dielectrics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang Mingmei; Kushner, Mark J.</p> <p>2010-01-15</p> <p>In high aspect ratio (HAR) plasma etching of holes and trenches in dielectrics, sporadic twisting is often observed. Twisting is the randomly occurring divergence of a hole or trench from the vertical. Many causes have been proposed for twisting, one of which is stochastic charging. As feature sizes shrink, the <span class="hlt">fluxes</span> of plasma particles, and ions in particular, into the feature become statistical. Randomly deposited charge by ions on the inside of a feature may be sufficient to produce lateral electric fields which divert incoming ions and initiate nonvertical etching or twisting. This is particularly problematic when etching with fluorocarbon gas mixtures where deposition of polymer in the feature may trap charge. dc-augmented capacitively coupled plasmas (dc-CCPs) have been investigated as a remedy for twisting. In these devices, high energy <span class="hlt">electron</span> (HEE) beams having narrow angular spreads can be generated. HEEs incident onto the wafer which penetrate into HAR features can neutralize the positive charge and so reduce the incidence of twisting. In this paper, we report on results from a computational investigation of plasma etching of SiO{sub 2} in a dc-CCP using Ar/C{sub 4}F{sub 8}/O{sub 2} gas mixtures. We found that HEE beams incident onto the wafer are capable of penetrating into features and partially neutralizing positive charge buildup due to sporadic ion charging, thereby reducing the incidence of twisting. Increasing the rf bias power increases the HEE beam energy and <span class="hlt">flux</span> with some indication of improvement of twisting, but there are also changes in the ion energy and <span class="hlt">fluxes</span>, so this is not an unambiguous improvement. Increasing the dc bias voltage while keeping the rf bias voltage constant increases the maximum energy of the HEE and its <span class="hlt">flux</span> while the ion characteristics remain nearly constant. For these conditions, the occurrence of twisting decreases with increasing HEE energy and <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/97156','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/97156"><span>Multi-satellite characterization of the large energetic <span class="hlt">electron</span> <span class="hlt">flux</span> increase at L = 4-7, in the five-day period following the March 24, 1991, solar energetic particle event</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ingraham, J.C.; Cayton, T.E.; Belian, R.D.</p> <p>1994-12-31</p> <p>Following the giant magnetic storm that started on March 24, 1991, and the immediately-preceding solar energetic particle (SEP) event, a dramatic increase in the <span class="hlt">flux</span> of energetic <span class="hlt">electrons</span> was observed to occur on several satellites (using Los Alamos instruments aboard two geosynchronous satellites and two GPS satellites, plus energetic <span class="hlt">electron</span> data from the CRRES satellite) sampling the L=4-7 region of the magne