Science.gov

Sample records for electromagnetics electron cooling

  1. Electron Cooling

    NASA Astrophysics Data System (ADS)

    Ellison, Timothy J. P.

    1991-08-01

    Electron cooling is a method of reducing the 6 -dimensional phase space volume of a stored ion beam. The technique was invented by Budker and first developed by him and his colleagues at the Institute for Nuclear Physics in Novosibirsk. Further studies of electron cooling were subsequently performed at CERN and Fermilab. At the Indiana University Cyclotron Facility (IUCF) an electron cooling system was designed, built, and commissioned in 1988. This was the highest energy system built to date (270 keV for cooling 500 MeV protons) and the first such system to be used as an instrument for performing nuclear and atomic physics experiments. This dissertation summarizes the design principles; measurements of the longitudinal drag rate (cooling force), equilibrium cooled beam properties and effective longitudinal electron beam temperature. These measurements are compared with theory and with the measured performance of other cooling systems. In addition the feasibility of extending this technology to energies an order of magnitude higher are discussed.

  2. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  3. MEIC electron cooling program

    SciTech Connect

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is a high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.

  4. MEIC electron cooling program

    DOE PAGES

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is amore » high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.« less

  5. Computational Electronics and Electromagnetics

    SciTech Connect

    DeFord, J.F.

    1993-03-01

    The Computational Electronics and Electromagnetics thrust area is a focal point for computer modeling activities in electronics and electromagnetics in the Electronics Engineering Department of Lawrence Livermore National Laboratory (LLNL). Traditionally, they have focused their efforts in technical areas of importance to existing and developing LLNL programs, and this continues to form the basis for much of their research. A relatively new and increasingly important emphasis for the thrust area is the formation of partnerships with industry and the application of their simulation technology and expertise to the solution of problems faced by industry. The activities of the thrust area fall into three broad categories: (1) the development of theoretical and computational models of electronic and electromagnetic phenomena, (2) the development of useful and robust software tools based on these models, and (3) the application of these tools to programmatic and industrial problems. In FY-92, they worked on projects in all of the areas outlined above. The object of their work on numerical electromagnetic algorithms continues to be the improvement of time-domain algorithms for electromagnetic simulation on unstructured conforming grids. The thrust area is also investigating various technologies for conforming-grid mesh generation to simplify the application of their advanced field solvers to design problems involving complicated geometries. They are developing a major code suite based on the three-dimensional (3-D), conforming-grid, time-domain code DSI3D. They continue to maintain and distribute the 3-D, finite-difference time-domain (FDTD) code TSAR, which is installed at several dozen university, government, and industry sites.

  6. ELECTRON COOLING FOR RHIC.

    SciTech Connect

    BEN-ZVI,I.

    2001-05-13

    The Accelerator Collider Department (CAD) at Brookhaven National Laboratory is operating the Relativistic Heavy Ion Collider (RHIC), which includes the dual-ring, 3.834 km circumference superconducting collider and the venerable AGS as the last part of the RHIC injection chain. CAD is planning on a luminosity upgrade of the machine under the designation RHIC II. One important component of the RHIC II upgrade is electron cooling of RHIC gold ion beams. For this purpose, BNL and the Budker Institute of Nuclear Physics in Novosibirsk entered into a collaboration aimed initially at the development of the electron cooling conceptual design, resolution of technical issues, and finally extend the collaboration towards the construction and commissioning of the cooler. Many of the results presented in this paper are derived from the Electron Cooling for RHIC Design Report [1], produced by the, BINP team within the framework of this collaboration. BNL is also collaborating with Fermi National Laboratory, Thomas Jefferson National Accelerator Facility and the University of Indiana on various aspects of electron cooling.

  7. Electron Cooling Study for MEIC

    SciTech Connect

    He, Zhang; Douglas, David R.; Derbenev, Yaroslav S.; Zhang, Yuhong

    2015-09-01

    Electron cooling of the ion beams is one critical R&D to achieve high luminosities in JLab's MEIC proposal. In the present MEIC design, a multi-staged cooling scheme is adapted, which includes DC electron cooling in the booster ring and bunched beam electron cooling in the collider ring at both the injection energy and the collision energy. We explored the feasibility of using both magnetized and non-magnetized electron beam for cooling, and concluded that a magnetized electron beam is necessary. Electron cooling simulation results for the newly updated MEIC design is also presented.

  8. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C. C.

    1997-02-01

    The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.

  9. Dynamical backaction cooling with free electrons.

    PubMed

    Niguès, A; Siria, A; Verlot, P

    2015-09-18

    The ability to cool single ions, atomic ensembles, and more recently macroscopic degrees of freedom down to the quantum ground state has generated considerable progress and perspectives in fundamental and technological science. These major advances have been essentially obtained by coupling mechanical motion to a resonant electromagnetic degree of freedom in what is generally known as laser cooling. Here, we experimentally demonstrate the first self-induced coherent cooling mechanism that is not mediated by an electromagnetic resonance. Using a focused electron beam, we report a 50-fold reduction of the motional temperature of a nanowire. Our result primarily relies on the sub-nanometre confinement of the electron beam and generalizes to any delayed and spatially confined interaction, with important consequences for near-field microscopy and fundamental nanoscale dissipation mechanisms.

  10. Dynamical backaction cooling with free electrons

    PubMed Central

    Niguès, A.; Siria, A.; Verlot, P.

    2015-01-01

    The ability to cool single ions, atomic ensembles, and more recently macroscopic degrees of freedom down to the quantum ground state has generated considerable progress and perspectives in fundamental and technological science. These major advances have been essentially obtained by coupling mechanical motion to a resonant electromagnetic degree of freedom in what is generally known as laser cooling. Here, we experimentally demonstrate the first self-induced coherent cooling mechanism that is not mediated by an electromagnetic resonance. Using a focused electron beam, we report a 50-fold reduction of the motional temperature of a nanowire. Our result primarily relies on the sub-nanometre confinement of the electron beam and generalizes to any delayed and spatially confined interaction, with important consequences for near-field microscopy and fundamental nanoscale dissipation mechanisms. PMID:26381454

  11. Electron microscopy of electromagnetic waveforms

    NASA Astrophysics Data System (ADS)

    Ryabov, A.; Baum, P.

    2016-07-01

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample’s oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available.

  12. Power electronics cooling apparatus

    DOEpatents

    Sanger, Philip Albert; Lindberg, Frank A.; Garcen, Walter

    2000-01-01

    A semiconductor cooling arrangement wherein a semiconductor is affixed to a thermally and electrically conducting carrier such as by brazing. The coefficient of thermal expansion of the semiconductor and carrier are closely matched to one another so that during operation they will not be overstressed mechanically due to thermal cycling. Electrical connection is made to the semiconductor and carrier, and a porous metal heat exchanger is thermally connected to the carrier. The heat exchanger is positioned within an electrically insulating cooling assembly having cooling oil flowing therethrough. The arrangement is particularly well adapted for the cooling of high power switching elements in a power bridge.

  13. Direct cooled power electronics substrate

    DOEpatents

    Wiles, Randy H [Powell, TN; Wereszczak, Andrew A [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Lowe, Kirk T [Knoxville, TN

    2010-09-14

    The disclosure describes directly cooling a three-dimensional, direct metallization (DM) layer in a power electronics device. To enable sufficient cooling, coolant flow channels are formed within the ceramic substrate. The direct metallization layer (typically copper) may be bonded to the ceramic substrate, and semiconductor chips (such as IGBT and diodes) may be soldered or sintered onto the direct metallization layer to form a power electronics module. Multiple modules may be attached to cooling headers that provide in-flow and out-flow of coolant through the channels in the ceramic substrate. The modules and cooling header assembly are preferably sized to fit inside the core of a toroidal shaped capacitor.

  14. Electronic cooling using thermoelectric devices

    SciTech Connect

    Zebarjadi, M.

    2015-05-18

    Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, and one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.

  15. Cooling system for electronic components

    DOEpatents

    Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

    2016-05-17

    Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

  16. Cooling system for electronic components

    SciTech Connect

    Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

    2015-12-15

    Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

  17. Electronics and Electromagnetism

    NASA Astrophysics Data System (ADS)

    Nièpce, J.-C.; Givord, D.

    Multilayer ceramic capacitors (MLCC) are the capacitors most commonly used in electronic circuits (television, radio, telephone, automobile, aeronautics, space, etc.). The main advantages are low cost, small size, a good level of chemical inertness, due to the fact that they are made from chemically very stable oxide ceramics, and hence good stability in time.

  18. Optimization of electron cooling in the Recycler

    SciTech Connect

    Shemyakin, A.; Burov, A.; Carlson, K.; Prost, L.R.; Sutherland, M.; Warner, A.; /Fermilab

    2009-04-01

    Antiprotons in Fermilab's Recycler ring are cooled by a 4.3 MeV, 0.1A DC electron beam (as well as by a stochastic cooling system). The paper describes electron cooling improvements recently implemented: adjustments of electron beam line quadrupoles to decrease the electron angles in the cooling section and better stabilization and control of the electron energy.

  19. Energy Efficient Electronics Cooling Project

    SciTech Connect

    Steve O'Shaughnessey; Tim Louvar; Mike Trumbower; Jessica Hunnicutt; Neil Myers

    2012-02-17

    Parker Precision Cooling Business Unit was awarded a Department of Energy grant (DE-EE0000412) to support the DOE-ITP goal of reducing industrial energy intensity and GHG emissions. The project proposed by Precision Cooling was to accelerate the development of a cooling technology for high heat generating electronics components. These components are specifically related to power electronics found in power drives focused on the inverter, converter and transformer modules. The proposed cooling system was expected to simultaneously remove heat from all three of the major modules listed above, while remaining dielectric under all operating conditions. Development of the cooling system to meet specific customer's requirements and constraints not only required a robust system design, but also new components to support long system functionality. Components requiring further development and testing during this project included pumps, fluid couplings, cold plates and condensers. All four of these major categories of components are required in every Precision Cooling system. Not only was design a key area of focus, but the process for manufacturing these components had to be determined and proven through the system development.

  20. Cooling Technology for Electronic Computers

    NASA Astrophysics Data System (ADS)

    Nakayama, Wataru

    The rapid growth of data processing speed in computers has been sustained by the advances in cooling technology. This article first presents a review of the published data of heat loads in recent Japanese large-scale computers. The survey indicates that, since around 1980, the high-level integration of microelectronic circuits has brought about almost four fold increase in the power dissipation from logic chips. The integration also has invited the evolutions of multichip modules and new schemes of electronic interconnections. Forced convection air-cooling and liquid cooling coupled with thermal connectors are discussed with reference to the designs employed in actual computers. More advanced cooling schemes are also discussed. Finally, the importance of thermal environmental control of computer rooms is emphasized.

  1. Coherent electron cooling demonstration experiment

    SciTech Connect

    Litvinenko, V.N.; Belomestnykh, S.; Ben-Zvi, I.; Brutus, J.C.; Fedotov, A.; Hao, Y.; Kayran, D.; Mahler, G.; Marusic, A.; Meng, W.; McIntyre, G.; Minty, M.; Ptitsyn, V.; Pinayev, I.; Rao, T.; Roser, T.; Sheehy, B.; Tepikian, S.; Than, R.; Trbojevic, D.; Tuozzolo, J.; Wang, G.; Yakimenko, V.; Hutton, A.; Krafft, G.; Poelker, M.; Rimmer, R.; Bruhwiler, D.; Abell, D.T.; Nieter, C.; Ranjbar, V.; Schwartz, B.; Kholopov M.; Shevchenko, O.; McIntosh, P.; Wheelhouse, A.

    2011-09-04

    Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using SRF linac. In this paper, we describe the setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC. We plan to complete the program in five years. During first two years we will build coherent electron cooler in IP2 of RHIC. In parallel we will develop complete package of computer simulation tools for the start-to-end simulation predicting exact performance of a CeC. The later activity will be the core of Tech X involvement into the project. We will use these tools to predict the performance of our CeC device. The experimental demonstration of the CeC will be undertaken in years three to five of the project. The goal of this experiment is to demonstrate the cooling of ion beam and to compare its measured performance with predictions made by us prior to the experiments.

  2. Improved cooling of electromagnetics by directed airflow

    NASA Astrophysics Data System (ADS)

    Fain, Adam Matthew

    The transformers in aircraft power conversion are often very heavy and represent a significant fuel or range penalty. Being thermally sized, improved cooling methods would allow downsizing and thereby reduced weight. Since the conductive paths in these metal "dense" devices are good, the controlling thermal resistance is typically the convective coefficient. The goal of this study was to optimize the convective air cooling across transformers by parametrically testing candidate shroud geometries to minimize average and hot spot surface temperatures with minimal fan power. A test set up was constructed that included a low velocity wind tunnel, fan, temperature and pressure sensors, DAQ system, and film heaters as well as the actual transformers. Experimental results from a low velocity wind tunnel were well predicted by CFD modeling, providing confidence in continued shroud development with only CFD or experimentally. Curved or bent types of shapes proved to be the most efficient shroud configurations in terms of maximizing heat transfer while reducing the energy requirement to achieve the desired level of cooling.

  3. Towards demonstration of electron cooling with bunched electron beam

    SciTech Connect

    Fedotov, A.

    2012-01-11

    All electron cooling systems which were in operation so far employed electron beam generated with an electrostatic electron gun in DC operating mode, immersed in a longitudinal magnetic field. At low energies magnetic field is also being used to transport electron beam through the cooling section from the gun to the collector. At higher energies (few MeV), it was shown that one can have simpler electron beam transport without continuous magnetic field. Because of a rather weak magnetic field on the cathode and in the cooling section the latter approach was referred to as 'non-magnetized cooling', since there was no suppression of the transverse angular spread of the electron beam with the magnetic field in the cooling section. Such a cooler successfully operated at FNAL (2005-11) at electron beam energy of 4.3 MeV. Providing cooling at even higher energies would be easier with RF acceleration of electron beam, and thus using bunched electron beam for cooling. Significant efforts were devoted to explore various aspects of such bunched electron beam cooling as part of R and D of high-energy electron cooling for RHIC. However, experimental studies of such cooling are still lacking. Establishing this technique experimentally would be extremely useful for future high-energy applications. Presently there is an ongoing effort to build Proof-of-Principle (PoP) experiment of Coherent Electron Cooling (CEC) at RHIC, which promises to be superior to conventional electron cooling for high energies. Since the CEC experiment is based on bunched electron beam and it has sections where electron beam co-propagates with the ion beam at the same velocity, it also provides a unique opportunity to explore experimentally conventional electron cooling but for the first time with a bunched electron beam. As a result, it allows us to explore techniques needed for the high-energy electron cooling such as 'painting' with a short electron beam and control of ion beam distribution under

  4. Direct Liquid Cooling for Electronic Equipment

    SciTech Connect

    Coles, Henry; Greenberg, Steve

    2014-03-01

    This report documents a demonstration of an electronic--equipment cooling system in the engineering prototype development stage that can be applied in data centers. The technology provides cooling by bringing a water--based cooling fluid into direct contact with high--heat--generating electronic components. This direct cooling system improves overall data center energy efficiency in three ways: High--heat--generating electronic components are more efficiently cooled directly using water, capturing a large portion of the total electronic equipment heat generated. This captured heat reduces the load on the less--efficient air--based data center room cooling systems. The combination contributes to the overall savings. The power consumption of the electronic equipment internal fans is significantly reduced when equipped with this cooling system. The temperature of the cooling water supplied to the direct cooling system can be much higher than that commonly provided by facility chilled water loops, and therefore can be produced with lower cooling infrastructure energy consumption and possibly compressor-free cooling. Providing opportunities for heat reuse is an additional benefit of this technology. The cooling system can be controlled to produce high return water temperatures while providing adequate component cooling. The demonstration was conducted in a data center located at Lawrence Berkeley National Laboratory in Berkeley, California. Thirty--eight servers equipped with the liquid cooling system and instrumented for energy measurements were placed in a single rack. Two unmodified servers of the same configuration, located in an adjacent rack, were used to provide a baseline. The demonstration characterized the fraction of heat removed by the direct cooling technology, quantified the energy savings for a number of cooling infrastructure scenarios, and provided information that could be used to investigate heat reuse opportunities. Thermal measurement data were used

  5. Attainment of Electron Beam Suitable for Medium Energy Electron Cooling

    SciTech Connect

    Seletskiy, Sergei M.

    2005-01-01

    Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The electron cooling project at Fermilab has recently demonstrated the ¯rst cooling of 8.9 GeV/c antiprotons in the Recycler ring, and therefore, has proved the validity of the idea of relativistic electron cool- ing. The Recycler Electron Cooler (REC) is the key component of the Teva- tron Run II luminosity upgrade project. Its performance depends critically on the quality of electron beam. A stable electron beam of 4.3 MeV car- rying 0.5 A of DC current is required. The beam suitable for the Recycler Electron Cooler must have an angular spread not exceeding 200 ¹rad. The full-scale prototype of the REC was designed, built and tested at Fermilab in the Wideband laboratory to study the feasibility of attaining the high-quality electron beam. In this thesis I describe various aspects of development of the Fermilab electron cooling system, and the techniques used to obtain the electron beam suitable for the cooling process. In particular I emphasize those aspects of the work for which I was principally responsible.

  6. ELECTRON COOLING IN THE RECYCLER COOLER

    SciTech Connect

    SHEMYAKIN,A.; PROST, L.R.; FEDOTOV, A.; SIDORIN, A.

    2007-09-10

    A 0.1-0.5 A, 4.3 MeV DC electron beam provides cooling of 8 GeV antiprotons in Fermilab's Recycler storage ring. The most detailed information about the cooling properties of the electron beam comes from drag rate measurements. We find that the measured drag rate can significantly differ from the cooling force experienced by a single antiproton because the area of effective cooling is significantly smaller than the physical size of the electron beam and is comparable with the size of the antiproton beam used as a probe. Modeling by the BETACOOL code supports the conclusion about a large radial gradient of transverse velocities in the presently used electron beam.

  7. Simulation study of electron response amplification in coherent electron cooling

    SciTech Connect

    Hao Y.; Litvinenko, V.N.

    2012-05-20

    In Coherent Electron Cooling (CEC), it is essential to study the amplification of electron response to a single ion in the FEL process, in order to proper align the electron beam and the ion beam in the kicker to maximize the cooling effect. In this paper, we use Genesis to simulate the amplified electron beam response of single ion in FEL amplification process, which acts as Green's function of the FEL amplifier.

  8. Classical electromagnetic radiation of the Dirac electron

    NASA Technical Reports Server (NTRS)

    Lanyi, G.

    1973-01-01

    A wave-function-dependent four-vector potential is added to the Dirac equation in order to achieve conservation of energy and momentum for a Dirac electron and its emitted electromagnetic field. The resultant equation contains solutions which describe transitions between different energy states of the electron. As a consequence it is possible to follow the space-time evolution of such a process. This evolution is shown in the case of the spontaneous emission of an electromagnetic field by an electron bound in a hydrogen-like atom. The intensity of the radiation and the spectral distribution are calculated for transitions between two eigenstates. The theory gives a self-consistent deterministic description of some simple radiation processes without using quantum electrodynamics or the correspondence principle.

  9. Thermoelectric Devices Cool, Power Electronics

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Nextreme Thermal Solutions Inc., based in Research Triangle Park, North Carolina, licensed thermoelectric technology from NASA s Jet Propulsion Laboratory. This has allowed the company to develop cutting edge, thin-film thermoelectric coolers that effective remove heat generated by increasingly powerful and tightly packed microchip components. These solid-state coolers are ideal solutions for applications like microprocessors, laser diodes, LEDs, and even potentially for cooling the human body. Nextreme s NASA technology has also enabled the invention of thermoelectric generators capable of powering technologies like medical implants and wireless sensor networks.

  10. Methods and apparatus for cooling electronics

    DOEpatents

    Hall, Shawn Anthony; Kopcsay, Gerard Vincent

    2014-12-02

    Methods and apparatus are provided for choosing an energy-efficient coolant temperature for electronics by considering the temperature dependence of the electronics' power dissipation. This dependence is explicitly considered in selecting the coolant temperature T.sub.0 that is sent to the equipment. To minimize power consumption P.sub.Total for the entire system, where P.sub.Total=P.sub.0+P.sub.Cool is the sum of the electronic equipment's power consumption P.sub.0 plus the cooling equipment's power consumption P.sub.Cool, P.sub.Total is obtained experimentally, by measuring P.sub.0 and P.sub.Cool, as a function of three parameters: coolant temperature T.sub.0; weather-related temperature T.sub.3 that affects the performance of free-cooling equipment; and computational state C of the electronic equipment, which affects the temperature dependence of its power consumption. This experiment provides, for each possible combination of T.sub.3 and C, the value T.sub.0* of T.sub.0 that minimizes P.sub.Total. During operation, for any combination of T.sub.3 and C that occurs, the corresponding optimal coolant temperature T.sub.0* is selected, and the cooling equipment is commanded to produce it.

  11. Power electronics substrate for direct substrate cooling

    DOEpatents

    Le, Khiet [Mission Viejo, CA; Ward, Terence G [Redondo Beach, CA; Mann, Brooks S [Redondo Beach, CA; Yankoski, Edward P [Corona, CA; Smith, Gregory S [Woodland Hills, CA

    2012-05-01

    Systems and apparatus are provided for power electronics substrates adapted for direct substrate cooling. A power electronics substrate comprises a first surface configured to have electrical circuitry disposed thereon, a second surface, and a plurality of physical features on the second surface. The physical features are configured to promote a turbulent boundary layer in a coolant impinged upon the second surface.

  12. Single Pass Electron Cooling Simulations for MEIC

    SciTech Connect

    Bell, G. I.; Pogorelov, I. V.; Schwartz, B. T.; Zhang, Yuhong; Zhang, He

    2013-12-01

    Cooling of medium energy protons is critical for the proposed Jefferson Lab Medium Energy Ion Collider (MEIC). We present simulations of electron cooling of protons up to 60 GeV. In the beam frame in which the proton and electrons are co-propagating, their motion is non-relativistic. We use a binary collision model which treats the cooling process as the sum of a large number of two-body collisions which are calculated exactly. This model can treat even very close collisions between an electron and ion with high accuracy. We also calculate dynamical friction using a delta-f PIC model. The code VSim (formerly Vorpal) is used to perform the simulations. We compare the friction rates with that obtained by a 3D integral over electron velocities which is used by BETACOOL.

  13. Method of fabricating a cooled electronic system

    DOEpatents

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2014-02-11

    A method of fabricating a liquid-cooled electronic system is provided which includes an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket. The method includes providing a liquid-cooled cold rail at the one end of the socket, and a thermal spreader to couple the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  14. IBS FOR ION DISTRIBUTION UNDER ELECTRON COOLING.

    SciTech Connect

    FEDOTOV,A.V.; BEN-ZVI,I.; EIDELMAN, YU.; LITVINENKO, V.; PARZEN, G.

    2005-05-16

    Standard models of the intra-beam scattering (IBS) are based on the growth of the rms beam parameters for a Gaussian distribution. As a result of electron cooling, the core of beam distribution is cooled much faster than the tails, producing a denser core. In this paper, we compare various approaches to IBS treatment for such distribution. Its impact on the luminosity is also discussed.

  15. Electron Cooling of Intense Ion Beam

    SciTech Connect

    Dietrich, J.; Kamerdjiev, V.; Maier, R.; Prasuhn, D.; Stein, J.; Stockhorst, H.; Korotaev, Yu.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2006-03-20

    Results of experimental studies of the electron cooling of a proton beam at COSY (Juelich, Germany) are presented. Intensity of the proton beam is limited by two general effects: particle loss directly after the injection and development of instability in a deep cooled ion beam. Results of the instability investigations performed at COSY during last years are presented in this report in comparison with previous results from HIMAC (Chiba, Japan) CELSIUS (Uppsala, Sweden) and LEAR (CERN). Methods of the instability suppression, which allow increasing the cooled beam intensity, are described. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584.

  16. Direct-Cooled Power Electronics Substrate

    SciTech Connect

    Wiles, R.; Ayers, C.; Wereszczak, A.

    2008-12-23

    The goal of the Direct-Cooled Power Electronics Substrate project is to reduce the size and weight of the heat sink for power electronics used in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). The concept proposed in this project was to develop an innovative power electronics mounting structure, model it, and perform both thermal and mechanical finite-element analysis (FEA). This concept involved integrating cooling channels within the direct-bonded copper (DBC) substrate and strategically locating these channels underneath the power electronic devices. This arrangement would then be directly cooled by water-ethylene glycol (WEG), essentially eliminating the conventional heat sink and associated heat flow path. The concept was evaluated to determine its manufacturability, its compatibility with WEG, and the potential to reduce size and weight while directly cooling the DBC and associated electronics with a coolant temperature of 105 C. This concept does not provide direct cooling to the electronics, only direct cooling inside the DBC substrate itself. These designs will take into account issues such as containment of the fluid (separation from the electronics) and synergy with the whole power inverter design architecture. In FY 2008, mechanical modeling of substrate and inverter core designs as well as thermal and mechanical stress FEA modeling of the substrate designs was performed, along with research into manufacturing capabilities and methods that will support the substrate designs. In FY 2009, a preferred design(s) will be fabricated and laboratory validation testing will be completed. In FY 2010, based on the previous years laboratory testing, the mechanical design will be modified and the next generation will be built and tested in an operating inverter prototype.

  17. Analytical studies of coherent electron cooling

    SciTech Connect

    Wang,G.; Blaskiewicz, M.; Litvinenko, V.N.

    2009-05-04

    Under certain assumptions and simplifications, we studied a few physics processes of Coherent Electron Cooling using analytical approach. In the modulation process, the effect due to merging the ion beam with the electron beam is studied under single kick approximation. In the free electron laser (FEL) amplifier, we studied the amplification of the electron density modulation using 1D analytical approach. Both the electron charge density and the phase space density are derived in the frequency domain. The solutions are then transformed into the space domain through Fast Fourier Transformation (FFT).

  18. Runaway electron generation in a cooling plasma

    SciTech Connect

    Smith, H.; Helander, P.; Eriksson, L.-G.; Fueloep, T.

    2005-12-15

    The usual calculation of Dreicer [Phys. Rev. 115, 238 (1959); 117, 329 (1960)] generation of runaway electrons assumes that the plasma is in a steady state. In a tokamak disruption this is not necessarily true since the plasma cools down quickly and the collision time for electrons at the runaway threshold energy can be comparable to the cooling time. The electron distribution function then acquires a high-energy tail which can easily be converted to a burst of runaways by the rising electric field. This process is investigated and simple criteria for its importance are derived. If no rapid losses of fast electrons occur, this can be a more important source of runaway electrons than ordinary Dreicer generation in tokamak disruptions.

  19. Cooling of electronics in collider experiments

    SciTech Connect

    Richard P. Stanek et al.

    2003-11-07

    Proper cooling of detector electronics is critical to the successful operation of high-energy physics experiments. Collider experiments offer unique challenges based on their physical layouts and hermetic design. Cooling systems can be categorized by the type of detector with which they are associated, their primary mode of heat transfer, the choice of active cooling fluid, their heat removal capacity and the minimum temperature required. One of the more critical detector subsystems to require cooling is the silicon vertex detector, either pixel or strip sensors. A general design philosophy is presented along with a review of the important steps to include in the design process. Factors affecting the detector and cooling system design are categorized. A brief review of some existing and proposed cooling systems for silicon detectors is presented to help set the scale for the range of system designs. Fermilab operates two collider experiments, CDF & D0, both of which have silicon systems embedded in their detectors. A review of the existing silicon cooling system designs and operating experience is presented along with a list of lessons learned.

  20. Potential Refrigerants for Power Electronics Cooling

    SciTech Connect

    Starke, M.R.

    2005-10-24

    In the past, automotive refrigerants have conventionally been used solely for the purpose of air conditioning. However, with the development of hybrid-electric vehicles and the incorporation of power electronics (PEs) into the automobile, automotive refrigerants are taking on a new role. Unfortunately, PEs have lifetimes and functionalities that are highly dependent on temperature and as a result thermal control plays an important role in the performance of PEs. Typically, PEs are placed in the engine compartment where the internal combustion engine (ICE) already produces substantial heat. Along with the ICE heat, the additional thermal energy produced by PEs themselves forces designers to use different cooling methods to prevent overheating. Generally, heat sinks and separate cooling loops are used to maintain the temperature. Disturbingly, the thermal control system can consume one third of the total volume and may weigh more than the PEs [1]. Hence, other avenues have been sought to cool PEs, including submerging PEs in automobile refrigerants to take advantage of two-phase cooling. The objective of this report is to explore the different automotive refrigerants presently available that could be used for PE cooling. Evaluation of the refrigerants will be done by comparing environmental effects and some thermo-physical properties important to two-phase cooling, specifically measuring the dielectric strengths of potential candidates. Results of this report will be used to assess the different candidates with good potential for future use in PE cooling.

  1. Effect of cooling rate on structural and electromagnetic properties of high-carbon ferrochrome powders

    NASA Astrophysics Data System (ADS)

    Yang, Jian-ping; Chen, Jin; Hao, Jiu-jiu; Guo, Li-na; Liu, Jin-ying

    2016-03-01

    The structural and electromagnetic properties of high-carbon ferrochrome powders (HCFCP) obtained at different cooling rates were respectively investigated by means of optical microscope, X-ray diffractometer, electron probe as well as the vector network analyzer in the frequency range of 1-18 GHz. The results show that the cell structure of main phase, (Cr,Fe)7C3, transforms from hexagonal to orthogonal with the improvement of cooling rate. Meanwhile the mass ratio of Cr to Fe in (Cr,Fe)7C3 gradually declines, while that for CrFe goes up. Both the real part and the imaginary part of relative complex permittivity of HCFCP are in an increasing order with cooling rate rising in most frequencies. For comparison, the relative complex permeability presents an opposite changing tendency. The peaks of the imaginary part of relative complex permeability appearing in low and high frequencies are attributed to nature resonance. The reflection loss of HCFCP gradually decreases as cooling rate reduces and frequency enhances. At 2.45 GHz, the algebraic sum of dielectric loss factor and magnetic loss factor increases first and then decreases in the temperature extent from 298 K to 1273 K.

  2. Two-Beam Instability in Electron Cooling

    SciTech Connect

    Burov, Alexey V.; /Fermilab

    2006-04-01

    The drift motion of cooling electrons makes them able to respond to transverse perturbations of a cooled ion beam. This response may lead to dipole or quadrupole transverse instabilities at specific longitudinal wave numbers. While the dipole instabilities can be suppressed by a combination of the Landau damping, machine impedance, and the active damper, the quadrupole and higher order modes can lead to either emittance growth, or a lifetime degradation, or both. The growth rates of these instabilities are strongly determined by the machine x-y coupling. Thus, tuning out of the coupling resonance and/or reduction of the machine coupling can be an efficient remedy for these instabilities.

  3. System for Cooling of Electronic Components

    NASA Astrophysics Data System (ADS)

    Vasil'ev, L. L.; Grakovich, L. P.; Dragun, L. A.; Zhuravlev, A. S.; Olekhnovich, V. A.; Rabetskii, M. I.

    2017-01-01

    Results of computational and experimental investigations of heat pipes having a predetermined thermal resistance and a system based on these pipes for air cooling of electronic components and diode assemblies of lasers are presented. An efficient compact cooling system comprising heat pipes with an evaporator having a capillary coating of a caked copper powder and a condenser having a developed outer finning, has been deviced. This system makes it possible to remove, to the ambient air, a heat flow of power more than 300 W at a temperature of 40-50°C.

  4. Electronic systems failures and anomalies attributed to electromagnetic interference

    NASA Technical Reports Server (NTRS)

    Leach, R. D. (Editor); Alexander, M. B. (Editor)

    1995-01-01

    The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems.

  5. Microbunched electron cooling for high-energy hadron beams.

    PubMed

    Ratner, D

    2013-08-23

    Electron and stochastic cooling are proven methods for cooling low-energy hadron beams, but at present there is no way of cooling hadrons as they near the TeV scale. In the 1980s, Derbenev suggested that electron instabilities, such as free-electron lasers, could create collective space charge fields strong enough to correct the hadron energies. This Letter presents a variation on Derbenev's electron cooling scheme using the microbunching instability as the amplifier. The large bandwidth of the instability allows for faster cooling of high-density beams. A simple analytical model illustrates the cooling mechanism, and simulations show cooling rates for realistic parameters of the Large Hadron Collider.

  6. ELECTRON COOLING SIMULATION FOR ARBITRARY DISTRIBUTION OF ELECTRONS

    SciTech Connect

    SIDORIN,A.; SMIRNOV, A.; FEDOTOV, A.; BEN-ZVI, I.; KAYRAN, D.

    2007-09-10

    Typically, several approximations are being used in simulation of electron cooling process, for example, density distribution of electrons is calculated using an analytical expression and distribution in the velocity space is assumed to be Maxwellian in all degrees of freedom. However, in many applications, accurate description of the cooling process based on realistic distribution of electrons is very useful. This is especially true for a high-energy electron cooling system which requires bunched electron beam produced by an Energy Recovery Linac (Em). Such systems are proposed, for instance, for RHIC and electron - ion collider. To address unique features of the RHIC-I1 cooler, new algorithms were introduced in BETACOOL code which allow us to take into account local properties of electron distribution as well as calculate friction force for an arbitrary velocity distribution. Here, we describe these new numerical models. Results based on these numerical models are compared with typical approximations using electron distribution produced by simulations of electron bunch through ERL of RHIC-II cooler.

  7. Controlled cooling of an electronic system for reduced energy consumption

    DOEpatents

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2016-08-09

    Energy efficient control of a cooling system cooling an electronic system is provided. The control includes automatically determining at least one adjusted control setting for at least one adjustable cooling component of a cooling system cooling the electronic system. The automatically determining is based, at least in part, on power being consumed by the cooling system and temperature of a heat sink to which heat extracted by the cooling system is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on one or more experimentally obtained models relating the targeted temperature and power consumption of the one or more adjustable cooling components of the cooling system.

  8. Electron Cooling in a Magnetically Expanding Plasma.

    PubMed

    Little, J M; Choueiri, E Y

    2016-11-25

    Electron cooling in a magnetically expanding plasma, which is a fundamental process for plasma flow and detachment in magnetic nozzles, is experimentally investigated using a radio frequency plasma source and magnetic nozzle (MN). Probe measurements of the plasma density, potential, and electron temperature along the center line of the MN indicate that the expansion follows a polytropic law with exponent γ_{e}=1.15±0.03. This value contradicts isothermal electron expansion, γ_{e}=1, which is commonly assumed in MN models. The axial variation of the measured quantities can be described by a simple quasi-1D fluid model with classical electron thermal conduction, for which it has been previously shown that a value of γ_{e}≈1.19 is expected in the weakly collisional limit. A new criterion, derived from the model, ensures efficient ion acceleration when a critical value for the ratio of convected to conducted power is exceeded.

  9. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    DOEpatents

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2016-04-05

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  10. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    DOEpatents

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2016-08-09

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  11. Adiabatic cooling of solar wind electrons

    NASA Technical Reports Server (NTRS)

    Sandbaek, Ornulf; Leer, Egil

    1992-01-01

    In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.

  12. Electromagnetic Dissociation and Spacecraft Electronics Damage

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    2016-01-01

    When protons or heavy ions from galactic cosmic rays (GCR) or solar particle events (SPE) interact with target nuclei in spacecraft, there can be two different types of interactions. The more familiar strong nuclear interaction often dominates and is responsible for nuclear fragmentation in either the GCR or SPE projectile nucleus or the spacecraft target nucleus. (Of course, the proton does not break up, except possibly to produce pions or other hadrons.) The less familiar, second type of interaction is due to the very strong electromagnetic fields that exist when two charged nuclei pass very close to each other. This process is called electromagnetic dissociation (EMD) and primarily results in the emission of neutrons, protons and light ions (isotopes of hydrogen and helium). The cross section for particle production is approximately defined as the number of particles produced in nucleus-nucleus collisions or other types of reactions. (There are various kinematic and other factors which multiply the particle number to arrive at the cross section.) Strong, nuclear interactions usually dominate the nuclear reactions of most interest that occur between GCR and target nuclei. However, for heavy nuclei (near Fe and beyond) at high energy the EMD cross section can be much larger than the strong nuclear interaction cross section. This paper poses a question: Are there projectile or target nuclei combinations in the interaction of GCR or SPE where the EMD reaction cross section plays a dominant role? If the answer is affirmative, then EMD mechanisms should be an integral part of codes that are used to predict damage to spacecraft electronics. The question can become more fine-tuned and one can ask about total reaction cross sections as compared to double differential cross sections. These issues will be addressed in the present paper.

  13. Controlled cooling of an electronic system based on projected conditions

    DOEpatents

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2015-08-18

    Energy efficient control of a cooling system cooling an electronic system is provided based, in part, on projected conditions. The control includes automatically determining an adjusted control setting(s) for an adjustable cooling component(s) of the cooling system. The automatically determining is based, at least in part, on projected power consumed by the electronic system at a future time and projected temperature at the future time of a heat sink to which heat extracted is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on an experimentally obtained model(s) relating the targeted temperature and power consumption of the adjustable cooling component(s) of the cooling system.

  14. Controlled cooling of an electronic system based on projected conditions

    DOEpatents

    David, Milnes P.; Iyengar, Madhusudan K.; Schmidt, Roger R.

    2016-05-17

    Energy efficient control of a cooling system cooling an electronic system is provided based, in part, on projected conditions. The control includes automatically determining an adjusted control setting(s) for an adjustable cooling component(s) of the cooling system. The automatically determining is based, at least in part, on projected power consumed by the electronic system at a future time and projected temperature at the future time of a heat sink to which heat extracted is rejected. The automatically determining operates to reduce power consumption of the cooling system and/or the electronic system while ensuring that at least one targeted temperature associated with the cooling system or the electronic system is within a desired range. The automatically determining may be based, at least in part, on an experimentally obtained model(s) relating the targeted temperature and power consumption of the adjustable cooling component(s) of the cooling system.

  15. A GPU Accelerated Simulation Program for Electron Cooling Process

    NASA Astrophysics Data System (ADS)

    Zhang, He; Huang, He; Li, Rui; Chen, Jie; Luo, Li-Shi

    2015-04-01

    Electron cooling is essential to achieve high luminosity in the medium energy electron ion collider (MIEC) project at Jefferson Lab. Bunched electron beam with energy above 50 MeV is used to cool coasting and/or bunched ion beams. Although the conventional electron cooling technique has been widely used, such an implementation in MEIC is still challenging. We are developing a simulation program for the electron cooling process to fulfill the need of the electron cooling system design for MEIC. The program simulates the evolution of the ion beam under the intrabeam scattering (IBS) effect and the electron cooling effect using Monte Carlo method. To accelerate the calculation, the program is developed on a GPU platform. We will present some preliminary simulation results. Work supported by the Department of Energy, Laboratory Directed Research and Development Funding, under Contract No. DE-AC05-06OR23177.

  16. ELECTRON COOLING AND ELECTRON-ION COLLIDERS AT BNL.

    SciTech Connect

    BEN-ZVI,I.

    2007-10-03

    Superconducting Energy Recovery Linacs (ERL) have significant potential uses in various fields, including High Energy Physics and Nuclear Physics. Brookhaven National Laboratory (BNL) is pursuing some of the potential applications in this area and the technology issues that are associated with these applications. The work addressed in this paper is carried out at BNL towards applications in electron cooling of high-energy hadron beams and electron-nucleon colliders. The common issues for these applications are the generation of high currents of polarized or high-brightness unpolarized electrons, high-charge per bunch and high-current. One must address the associated issue of High-Order Modes generation and damping. Superconducting ERLs have great advantages for these applications as will be outlined in the text.

  17. Fundamental research on convective heat transfer in electronic cooling technology

    NASA Astrophysics Data System (ADS)

    Ma, C. F.; Gan, Y. P.; Tian, Y. Q.; Lei, D. H.

    1992-03-01

    During the past six years comprehensive research programs have been conducted at the Beijing Polytechnic University to provide a better understanding of heat transfer characteristics of existing and condidate cooling techniques for electronic and microelectronic devices. This paper provides a review and summary of the programs with emphasis on direct liquid cooling. Included in this review are the heat transfer investigations related to the following cooling modes: liquid free, mixed and forced convection, liquid jet impingement, flowing liquid film cooling, pool boiling, spray cooling, foreign gas jet impingement in liquid pool, and forced convection air-cooling.

  18. Electron acceleration in the ionosphere by obliquely propagating electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Burke, William J.; Ginet, Gregory P.; Heinemann, Michael A.; Villalon, Elena

    The paper presents an analysis of the relativistic equations of motion for electrons in magnetized plasma and externally imposed electromagnetic fields that propagate at arbitrary angles to the background magnetic field. The relativistic Lorentz equation for a test electron moving under the influence of an electromagnetic wave in a cold magnetized plasma and wave propagation through the ionospheric 'radio window' are examined. It is found that at wave energy fluxes greater than 10 to the 8th mW/sq m, initially cold electrons can be accelerated to energies of several MeV in less than a millisecond. Plans to test the theoretical results with rocket flights are discussed.

  19. Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

    SciTech Connect

    Hershcovitch,A.

    2008-04-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter.

  20. Development of the electron cooling simulation program for JLEIC

    SciTech Connect

    Zhang, He; Chen, Jie; Li, Rui; Zhang, Yuhong; Huang, He; Luo, Li-Shi

    2016-05-01

    In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during collision at the collider ring. A new electron cooling process simulation program has been developed to fulfill the requirements of the JLEIC electron cooler design. The new program allows the users to calculate the electron cooling rate and simulate the cooling process with either DC or bunched electron beam to cool either coasting or bunched ion beam. It has been benchmarked with BETACOOL in aspect of accuracy and efficiency. In typical electron cooling process of JLEIC, the two programs agree very well and we have seen a significant improvement of computational speed using the new one. Being adaptive to the modern multicore hardware makes it possible to further enhance the efficiency for computationally intensive problems. The new program is being actively used in the electron cooling study and cooler design for JLEIC. We will present our models and some simulation results in this paper.

  1. PROGRESS OF HIGH-ENERGY ELECTRON COOLING FOR RHIC.

    SciTech Connect

    FEDOTOV,A.V.

    2007-09-10

    The fundamental questions about QCD which can be directly answered at Relativistic Heavy Ion Collider (RHIC) call for large integrated luminosities. The major goal of RHIC-I1 upgrade is to achieve a 10 fold increase in luminosity of Au ions at the top energy of 100 GeV/nucleon. Such a boost in luminosity for RHIC-II is achievable with implementation of high-energy electron cooling. The design of the higher-energy cooler for RHIC-II recently adopted a non-magnetized approach which requires a low temperature electron beam. Such electron beams will be produced with a superconducting Energy Recovery Linac (ERL). Detailed simulations of the electron cooling process and numerical simulations of the electron beam transport including the cooling section were performed. An intensive R&D of various elements of the design is presently underway. Here, we summarize progress in these electron cooling efforts.

  2. Cooling systems and hybrid A/C systems using an electromagnetic radiation-absorbing complex

    DOEpatents

    Halas, Nancy J.; Nordlander, Peter; Neumann, Oara

    2015-05-19

    A method for powering a cooling unit. The method including applying electromagnetic (EM) radiation to a complex, where the complex absorbs the EM radiation to generate heat, transforming, using the heat generated by the complex, a fluid to vapor, and sending the vapor from the vessel to a turbine coupled to a generator by a shaft, where the vapor causes the turbine to rotate, which turns the shaft and causes the generator to generate the electric power, wherein the electric powers supplements the power needed to power the cooling unit

  3. Electron cooling for low-energy RHIC program

    SciTech Connect

    Fedotov, A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.N.; Pendzick, A.; Satogata, T.

    2009-08-31

    Electron cooling was proposed to increase luminosity of the RHIC collider for heavy ion beam energies below 10 GeV/nucleon. Providing collisions at such energies, termed RHIC 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. The electron cooling system should deliver electron beam of required good quality over energies of 0.9-5 MeV. Several approaches to provide such cooling were considered. The baseline approach was chosen and design work started. Here we describe the main features of the cooling system and its expected performance. We have started design work on a low-energy RHIC electron cooler which will operate with kinetic electron energy range 0.86-2.8 (4.9) MeV. Several approaches to an electron cooling system in this energy range are being investigated. At present, our preferred scheme is to transfer the Fermilab Pelletron to BNL after Tevatron shutdown, and to use it for DC non-magnetized cooling in RHIC. Such electron cooling system can significantly increase RHIC luminosities at low-energy operation.

  4. Detectors for low energy electron cooling in RHIC

    SciTech Connect

    Carlier, F. S.

    2016-02-15

    Low energy operation of RHIC is of particular interest to study the location of a possible critical point in the QCD phase diagram. The performance of RHIC at energies equal to or lower than 10 GV/nucleon is limited by nonlinearities, Intra-BeamScattering (IBS) processes and space-charge effects. To successfully address the luminosity and ion store lifetime limitations imposed by IBS the method of electron cooling has been envisaged. During electron cooling processes electrons are injected along with the ion beam at the nominal ion bunch velocities. The velocity spread of the ion beam is reduced in all planes through Coulomb interactions between the cold electron beam and the ion beam. The electron cooling system proposed for RHIC will be the first of its kind to use bunched beams for the delivery of the electron bunches, and will therefore be accompanied by the necessary challenges. The designed electron cooler will be located in IP2. The electron bunches will be accelerated by a linac before being injected along side the ion beams. Thirty consecutive electron bunches will be injected to overlap with a single ion bunch. They will first cool the yellow beam before being extracted turned by 180-degrees and reinjected into the blue beam for cooling. As such, both the yellow and blue beams will be cooled by the same ion bunches. This will pose considerable challenges to ensure proper electron beam quality to cool the second ion beam. Furthermore, no ondulator will be used in the electron cooler so radiative recombination between the ions and the electrons will occur.

  5. Use of an Electron Beam for Stochastic Cooling

    SciTech Connect

    Yaroslave Derbenev

    2007-09-10

    Microwave instability of an electron beam can be used for a multiple increase in the collective response for the perturbation caused by a particle of a co-moving ion beam, i.e. for enhancement of friction force in electron cooling method. The low scale (hundreds GHz and higher frequency range) space charge or FEL type instabilities can be produced (depending on conditions) by introducing an alternating magnetic fields along the electron beam path. Beams’ optics and noise conditioning for obtaining a maximal cooling effect and related limitations will be discussed. The method promises to increase by a few orders of magnitude the cooling rate for heavy particle beams with a large emittance for a wide energy range with respect to either electron and conventional stochastic cooling.

  6. Cooling Methods for High-Power Electronic Systems

    NASA Astrophysics Data System (ADS)

    Blinov, Andrei; Vinnikov, Dmitri; Lehtla, Tõnu

    2011-01-01

    Thermal management is a crucial step in the design of power electronic applications, especially railroad traction and automotive systems. Mass/size parameters, robustness and reliability of the power electronic system greatly depend on the cooling system type and performance. This paper presents an approximate parameter estimation of the thermal management system required as well as different commercially available cooling solutions. Advantages and drawbacks of different designs ranging from simple passive heatsinks to complex evaporative systems are discussed.

  7. The integration of cryogenic cooling systems with superconducting electronic systems

    SciTech Connect

    Green, Michael A.

    2003-07-01

    The need for cryogenic cooling has been critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of the superconducting circuit is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a disadvantage. This report will talk about the various methods for refrigerating superconducting devices. Cryocooler types will be compared for vibration, efficiency, and cost. Some solutions to specific problems of integrating cryocoolers to superconducting devices are presented.

  8. Hole Cooling Is Much Faster than Electron Cooling in PbSe Quantum Dots.

    PubMed

    Spoor, Frank C M; Kunneman, Lucas T; Evers, Wiel H; Renaud, Nicolas; Grozema, Ferdinand C; Houtepen, Arjan J; Siebbeles, Laurens D A

    2016-01-26

    In semiconductor quantum dots (QDs), charge carrier cooling is in direct competition with processes such as carrier multiplication or hot charge extraction that may improve the light conversion efficiency of photovoltaic devices. Understanding charge carrier cooling is therefore of great interest. We investigate high-energy optical transitions in PbSe QDs using hyperspectral transient absorption spectroscopy. We observe bleaching of optical transitions involving higher valence and conduction bands upon band edge excitation. The kinetics of rise of the bleach of these transitions after a pump laser pulse allow us to monitor, for the first time, cooling of hot electrons and hot holes separately. Our results show that holes cool significantly faster than electrons in PbSe QDs. This is in contrast to the common assumption that electrons and holes behave similarly in Pb chalcogenide QDs and has important implications for the utilization of hot charge carriers in photovoltaic devices.

  9. Testing aspects of advanced coherent electron cooling technique

    SciTech Connect

    Litvinenko, V.; Jing, Y.; Pinayev, I.; Wang, G.; Samulyak, R.; Ratner, D.

    2015-05-03

    An advanced version of the Coherent-electron Cooling (CeC) based on the micro-bunching instability was proposed. This approach promises significant increase in the bandwidth of the CeC system and, therefore, significant shortening of cooling time in high-energy hadron colliders. In this paper we present our plans of simulating and testing the key aspects of this proposed technique using the set-up of the coherent-electron-cooling proof-of-principle experiment at BNL.

  10. Emerging Two-Phase Cooling Technologies for Power Electronic Inverters

    SciTech Connect

    Hsu, J.S.

    2005-08-17

    In order to meet the Department of Energy's (DOE's) FreedomCAR and Vehicle Technologies (FVCT) goals for volume, weight, efficiency, reliability, and cost, the cooling of the power electronic devices, traction motors, and generators is critical. Currently the power electronic devices, traction motors, and generators in a hybrid electric vehicle (HEV) are primarily cooled by water-ethylene glycol (WEG) mixture. The cooling fluid operates as a single-phase coolant as the liquid phase of the WEG does not change to its vapor phase during the cooling process. In these single-phase systems, two cooling loops of WEG produce a low temperature (around 70 C) cooling loop for the power electronics and motor/generator, and higher temperature loop (around 105 C) for the internal combustion engine. There is another coolant option currently available in automobiles. It is possible to use the transmission oil as a coolant. The oil temperature exists at approximately 85 C which can be utilized to cool the power electronic and electrical devices. Because heat flux is proportional to the temperature difference between the device's hot surface and the coolant, a device that can tolerate higher temperatures enables the device to be smaller while dissipating the same amount of heat. Presently, new silicon carbide (SiC) devices and high temperature direct current (dc)-link capacitors, such as Teflon capacitors, are available but at significantly higher costs. Higher junction temperature (175 C) silicon (Si) dies are gradually emerging in the market, which will eventually help to lower hardware costs for cooling. The development of high-temperature devices is not the only way to reduce device size. Two-phase cooling that utilizes the vaporization of the liquid to dissipate heat is expected to be a very effective cooling method. Among two-phase cooling methods, different technologies such as spray, jet impingement, pool boiling and submersion, etc. are being developed. The Oak Ridge

  11. The role of electron heating in electromagnetic collisionless shock formation

    NASA Astrophysics Data System (ADS)

    Bochkarev, S. G.; d'Humières, E.; Korneev, Ph.; Bychenkov, V. Yu.; Tikhonchuk, V.

    2015-12-01

    The role of electron dynamics in the process of a collisionless shock formation is analyzed with particle-in-cell simulations, the test-particles method, and quasilinear theory. The model of electron stochastic heating in turbulent electromagnetic fields corresponding to the nonlinear stage of two-stream and Weibel instabilities is developed. The analysis of electron and field heating rates shows that the ion motion provides the energy supply for a significant continuous heating of electrons. Such a heating thus plays a role of a friction force for ions, leading to their deceleration and a shock formation.

  12. Effects of e-beam parameters on coherent electron cooling

    SciTech Connect

    Webb, S.D.; Litvinenko, V.N.; Wang, G.

    2011-03-28

    Coherent Electron Cooling (CeC) requires detailed control of the phase between the hadron an the FEL-amplified wave packet. This phase depends on local electron beam parameters such as the energy spread and the peak current. In this paper, we examine the effects of local density variations on the cooling rates for CeC. Coherent Electron Cooling (CeC) [1] is a new concept in intense, high energy hadron beamcooling, in which the Debye screened charge perturbation calculated in [2] is used to seed a high-gain free electron laser (FEL). Using delays to give the perturbing hadron an energy-dependent longitudinal displacement relative to its frequencymodulated charge perturbation, the hadron receives an energy-dependent kick which reduces its energy variation from the design energy. The equations of motion in [1] assume that the electron bunch is the same physical size as the hadron bunch, and has a homogeneous charge density across the entire bunch. In practice, the electron bunches will be much shorter than the hadron bunch, and this local spacial inhomogeneity in the charge distribution will alter the gain length of the FEL, resulting in both a change in the amplification of the initial signal and a phase shift. In this paper we consider these inhomogeneity effects, determining cooling equations for bunched beam CeC consistent with these effects and determining thresholds for the cooling parameters.

  13. Partially ferromagnetic electromagnet for trapping and cooling neutral atoms to quantum degeneracy

    SciTech Connect

    Fauquembergue, M.; Riou, J-F.; Guerin, W.; Rangwala, S.; Moron, F.; Villing, A.; Le Coq, Y.; Bouyer, P.; Aspect, A.; Lecrivain, M.

    2005-10-15

    We have developed a compact partially ferromagnetic electromagnet to produce an Ioffe-Pritchard trap for neutral atoms. Our structure permits strong magnetic confinement with low power consumption. Compared to the previous iron-core electromagnet [B. Desruelle, V. Boyer, P. Bouyer, G. Birkl, M. Lecrivain, F. Alves, C. Westbrook, and A. Aspect, Eur. Phys. J. D 1, 255 (1998)], it allows for easy compensation of remnant fields and very high stability, along with cost-effective realization and compactness. We describe and characterize our apparatus and demonstrate trapping and cooling of {sup 87}Rb atoms to quantum degeneracy. Pure Bose-Einstein condensates containing 10{sup 6} atoms are routinely realized on a half-minute cycle. In addition we test the stability of the magnetic trap by producing atom lasers.

  14. Relativistic electromagnetic waves in an electron-ion plasma

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  15. Control of electronic transport in graphene by electromagnetic dressing

    PubMed Central

    Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.

    2016-01-01

    We demonstrated theoretically that the renormalization of the electron energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) electronic transport in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control electronic properties of graphene with light. PMID:26838371

  16. Path integral approach to electron scattering in classical electromagnetic potential

    NASA Astrophysics Data System (ADS)

    Chuang, Xu; Feng, Feng; Ying-Jun, Li

    2016-05-01

    As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374360, 11405266, and 11505285) and the National Basic Research Program of China (Grant No. 2013CBA01504).

  17. ELECTRON COOLING IN THE PRESENCE OF UNDULATOR FIELDS

    SciTech Connect

    FEDOTOV,A.; BEN-ZVI, I.; ET AL.

    2007-06-25

    The design of the higher-energy cooler for Relativistic Heavy Ion Collider (RHIC) recently adopted a non-magnetized approach which requires a low temperature electron beam. However, to avoid significant loss of heavy ions due to recombination with electrons in the cooling section, the temperature of the electron beam should be high. These two contradictory requirements are satisfied in the design of the RWIC cooler with the help of the undulator fields. The model of the friction force in the presence of an undulator field was benchmarked vs. direct numerical simulations with an excellent agreement. Here, we discuss cooling dynamics simulations with a helical undulator, including recombination suppression and resulting luminosities.

  18. Direct electronic measurement of Peltier cooling and heating in graphene.

    PubMed

    Vera-Marun, I J; van den Berg, J J; Dejene, F K; van Wees, B J

    2016-05-10

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials.

  19. Direct electronic measurement of Peltier cooling and heating in graphene

    NASA Astrophysics Data System (ADS)

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-05-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials.

  20. Direct electronic measurement of Peltier cooling and heating in graphene

    PubMed Central

    Vera-Marun, I. J.; van den Berg, J. J.; Dejene, F. K.; van Wees, B. J.

    2016-01-01

    Thermoelectric effects allow the generation of electrical power from waste heat and the electrical control of cooling and heating. Remarkably, these effects are also highly sensitive to the asymmetry in the density of states around the Fermi energy and can therefore be exploited as probes of distortions in the electronic structure at the nanoscale. Here we consider two-dimensional graphene as an excellent nanoscale carbon material for exploring the interaction between electronic and thermal transport phenomena, by presenting a direct and quantitative measurement of the Peltier component to electronic cooling and heating in graphene. Thanks to an architecture including nanoscale thermometers, we detected Peltier component modulation of up to 15 mK for currents of 20 μA at room temperature and observed a full reversal between Peltier cooling and heating for electron and hole regimes. This fundamental thermodynamic property is a complementary tool for the study of nanoscale thermoelectric transport in two-dimensional materials. PMID:27161186

  1. Slow Electron Cooling in Colloidal Quantum Dots

    NASA Astrophysics Data System (ADS)

    Pandey, Anshu; Guyot-Sionnest, Philippe

    2008-11-01

    Hot electrons in semiconductors lose their energy very quickly (within picoseconds) to lattice vibrations. Slowing this energy loss could prove useful for more efficient photovoltaic or infrared devices. With their well-separated electronic states, quantum dots should display slow relaxation, but other mechanisms have made it difficult to observe. We report slow intraband relaxation (>1 nanosecond) in colloidal quantum dots. The small cadmium selenide (CdSe) dots, with an intraband energy separation of ~0.25 electron volts, are capped by an epitaxial zinc selenide (ZnSe) shell. The shell is terminated by a CdSe passivating layer to remove electron traps and is covered by ligands of low infrared absorbance (alkane thiols) at the intraband energy. We found that relaxation is markedly slowed with increasing ZnSe shell thickness.

  2. Atom-membrane cooling and entanglement using cavity electromagnetically induced transparency

    SciTech Connect

    Genes, Claudiu; Ritsch, Helmut; Drewsen, Michael; Dantan, Aurelien

    2011-11-15

    We investigate a hybrid optomechanical system composed of a micromechanical oscillator as a movable membrane and an atomic three-level ensemble within an optical cavity. We show that a suitably tailored cavity field response via electromagnetically induced transparency (EIT) in the atomic medium allows for strong coupling of the membrane's mechanical oscillations to the collective atomic ground-state spin. This facilitates ground-state cooling of the membrane motion, quantum state mapping, and robust atom-membrane entanglement even for cavity widths larger than the mechanical resonance frequency.

  3. Electromagnetic electron temperature gradient driven instability in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Zielinski, J.; Smolyakov, A. I.; Beyer, P.; Benkadda, S.

    2017-02-01

    The fluid theory of a new type of electron temperature gradient instability is proposed. This mode is closely related to the short wavelength Alfvén mode in the regime k⊥ 2 ρi 2 > 1 . Contrary to standard electron temperature gradient modes, which are mostly electrostatic, the considered mode is fundamentally electromagnetic and does not exist in the electrostatic limit. The mechanism of instability relies on gradients in both the electron temperature and magnetic field. It is suggested that this instability may be a destabilizing mechanism for collisionless microtearing modes, which are observed in a number of gyrokinetic simulations.

  4. ELECTRON COOLING SIMULATIONS FOR LOW-ENERGY RHIC OPERATION.

    SciTech Connect

    FEDOTOV,A.V.; BEN-ZVI, I.; CHANG, X.; KAYRAN, D.; SATOGATA, T.

    2007-09-10

    Recently, a strong interest emerged in running the Relativistic Heavy Ion Collider (RHIC) at low beam total energies of 2.5-25 GeV/nucleon, substantially lower than the nominal beam total energy of 100 GeV/nucleon. Collisions in this low energy range are motivated by one of the key questions of quantum chromodynamics (QCD) about the existence and location of critical point on the QCD phase diagram. Applying electron cooling directly at these low energies in RHIC would result in significant luminosity increase and long beam stores for physics. Without direct cooling in RHIC at these low energies, beam lifetime and store times are very short, limited by strong transverse and longitudinal intrabeam scattering (IBS). In addition, for the lowest energies of the proposed energy scan, the longitudinal emittance of ions injected from the AGS into RHIC may be too big to fit into the RHIC RF bucket. An improvement in the longitudinal emittance of the ion beam can be provided by an electron cooling system at the AGS injection energy. Simulations of electron cooling both for direct cooling at low energies in RHIC and for injection energy cooling in the AGS were performed and are summarized in this report.

  5. Electromagnetic and thermal analysis of distributed cooled high power millimeter wave windows

    SciTech Connect

    Nelson, S.D.; Reitter, T.; Caplan, M.

    1995-05-12

    The sectional high-frequency internally-cooled window, as proposed by General Atomics, has unique potential for allowing microwave sources to reach multi-megawatt CW levels with application to ECRH. Designs are being investigated using computational electromagnetic (EM), thermal, and mechanical codes at 110 GHz and 170 GHz to examine the design tradeoffs between RF performance and thermal mechanical safety margins. The EM analyses are for the window, under vacuum at one MW and includes variations in the shapes of the cooling fins, the surface treatment of the window elements themselves, the cooling fin tip treatment, the window pitch angle, and the waveguide effects. One advantage of the distributed cooled window is it`s extensibility to higher power levels. Results in the modeling efforts are presented showing the EM field concentrations (which then will feed into the thermal analysis), the energy scattering/reflection, the transmitted launch angle variation as a function of physical geometry, and the spatial energy distribution and loss as a function of time and position.

  6. HIGH-ENERGY ELECTRON COOLING BASED ON REALISTIC SIX-DIMENSIONAL DISTRIBUTION OF ELECTRONS

    SciTech Connect

    FEDOTOV,A.; BEN-ZVI, I.; ET AL.

    2007-06-25

    The high-energy electron cooling system for RHIC-II is unique compared to standard coolers. It requires bunched electron beam. Electron bunches are produced by an Energy Recovery Linac (ERL), and cooling is planned without longitudinal magnetic field. To address unique features of the RHIC cooler, a generalized treatment of cooling force was introduced in BETACOOE code which allows us to calculate friction force for an arbitrary distribution of electrons. Simulations for RHIC cooler based on electron distribution from ERL are presented.

  7. Search for electron EDM with laser cooled radioactive atom

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, T.; Kawamura, H.; Nataraj, H. S.; Sato, T.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Sakemi, Y.

    2013-05-01

    The permanent electric dipole moment (EDM) of the elementary particle has the sensitivity to the CP violation in the theories beyond the standard model (SM). The search for the EDM constitutes the stringent test to discriminate between the SM and beyond it. We plan to perform the electron EDM search by using the laser cooled francium (Fr) atom which has the largest enhancement factor of the electron EDM in the alkali atoms. In this paper, the present status of the laser cooled Fr factory that is being constructed at Cyclotron and Radioisotope Center (CYRIC), Tohoku University are reported.

  8. Passive Two-Phase Cooling of Automotive Power Electronics: Preprint

    SciTech Connect

    Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.

    2014-08-01

    Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated, and tests were conducted using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator design that incorporates features to improve performance and reduce size was conceived. Simulation results indicate its thermal resistance can be 37% to 48% lower than automotive dual side cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers--plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.

  9. Passive Two-Phase Cooling for Automotive Power Electronics

    SciTech Connect

    Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.

    2014-01-01

    Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated and tested using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245 fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator concept that incorporates features to improve performance and reduce its size was designed. Simulation results indicate the concept's thermal resistance can be 58% to 65% lower than automotive dual-side-cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers-plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.

  10. Electromagnetic beam modes driven by anisotropic electron streams

    NASA Technical Reports Server (NTRS)

    Goldman, Martin V.; Newman, David

    1987-01-01

    A theory is presented which provides an explanation for recent laboratory observations of a 'new electromagnetic' mode in a non-Maxwellian high-beta plasma' and suggests a likely relevance of these modes to space plasmas. Unstable parallel-propagating waves, which can be beam modes or whistlers, depending mainly on the degree of velocity anisotropy in a weak electron beam, are found. In the beam-mode limit relevant to the experiment, this is a kinetic Weibel instability, enhanced by a parallel magnetic field. The frequency of the mode can be above or below the electron cyclotron frequency.

  11. Nonresonant interactions of electromagnetic ion cyclotron waves with relativistic electrons

    NASA Astrophysics Data System (ADS)

    Chen, Lunjin; Thorne, Richard M.; Bortnik, Jacob; Zhang, Xiao-Jia

    2016-10-01

    The dynamics of relativistic electrons traveling through a parallel-propagating, monochromatic electromagnetic ion cyclotron (EMIC) wave in the Earth's dipole field are investigated via test particle simulations. Both resonant and nonresonant responses in electron pitch angle are considered, and the differences between the two are highlighted. Nonresonant electrons, with energies below the minimum resonant energy down to hundreds of keV, are scattered stochastically in pitch angle and can be scattered into the atmospheric loss cone. The nonresonant effect is attributed to the spatial edge associated with EMIC wave packets. A condition for effective nonresonant response is also provided. This effect is excluded from current quasi-linear theory and can be a potentially important loss mechanism of relativistic and subrelativistic electrons in the radiation belts.

  12. Electronic cooling of a submicron-sized metallic beam

    NASA Astrophysics Data System (ADS)

    Muhonen, J. T.; Niskanen, A. O.; Meschke, M.; Pashkin, Yu. A.; Tsai, J. S.; Sainiemi, L.; Franssila, S.; Pekola, J. P.

    2009-02-01

    We demonstrate electronic cooling of a suspended AuPd island using superconductor-insulator-normal metal tunnel junctions. This was achieved by developing a simple fabrication method for reliably releasing narrow submicron-sized metal beams. The process is based on reactive ion etching and uses a conducting substrate to avoid charge-up damage and is compatible with, e.g., conventional e-beam lithography, shadow-angle metal deposition, and oxide tunnel junctions. The devices function well and exhibit clear cooling, up to a factor of 2 at sub-Kelvin temperatures.

  13. Physical installation of Pelletron and electron cooling system

    SciTech Connect

    Hurh, P.

    1997-09-01

    Bremsstrahlung of 5 MeV electrons at a loss current of 50 microamp in the acceleration region is estimated to produce X-ray intensities of 7 Rad/sec. Radiation losses due to a misteer or sudden obstruction will of course be much higher still (estimated at 87,500 Rad/hr for a 0.5 mA beam current). It is estimated that 1.8 meters of concrete will be necessary to adequately shield the surrounding building areas at any possible Pelletron installation site. To satisfy our present electron cooling development plan, two Pelletron installations are required, the first at our development lab in the Lab B/NEF Enclosure area and the second at the operational Main Injector service building, MI-30, in the main Injector ring. The same actual Pelletron and electron beam-line components will be used at both locations. The Lab B installation will allow experimentation with actual high energy electron beam to develop the optics necessary for the cooling straight while Main Injector/Recycler commissioning is taking place. The MI-30 installation is obviously the permanent home for the Pelletron when electron cooling becomes operational. Construction plans for both installations will be discussed here.

  14. Mitigation of biofouling using electromagnetic fields in tubular heat exchangers-condensers cooled by seawater.

    PubMed

    Trueba, Alfredo; García, Sergio; Otero, Félix M

    2014-01-01

    Electromagnetic field (EMF) treatment is presented as an alternative physical treatment for the mitigation of biofouling adhered to the tubes of a heat exchanger-condenser cooled by seawater. During an experimental phase, a fouling biofilm was allowed to grow until experimental variables indicated that its growth had stabilised. Subsequently, EMF treatment was applied to seawater to eliminate the biofilm and to maintain the achieved cleanliness. The results showed that EMFs precipitated ions dissolved in the seawater. As a consequence of the application of EMFs, erosion altered the intermolecular bonding of extracellular polymers, causing the destruction of the biofilm matrix and its detachment from the inner surface of the heat exchanger-condenser tubes. This detachment led to the partial removal of a mature biofilm and a partial recovery of the efficiency lost in the heat transfer process by using a physical treatment that is harmless to the marine environment.

  15. Part II/Addendum Electron Beam Cooling between EBIS LINAC and Booster; Is Single Pass Cooling Possible?

    SciTech Connect

    Hershcovitch,A.

    2008-07-01

    Due to some miscommunication, incomplete data was erroneously used in examining electron beam cooling for reducing momentum of gold ions exiting the EBIS LINAC before injection into the booster. Corrected calculations still indicate that single pass cooling is, in principle, feasible; momentum spread can be reduced by an order of magnitude in about one meter. Preliminary results suggest that this cooling deserves further consideration.

  16. Two-Phase Cooling Method Using R134a Refrigerant to Cool Power Electronic Devices

    SciTech Connect

    Lowe, Kirk T; Tolbert, Leon M; Ayers, Curtis William; Ozpineci, Burak; Campbell, Jeremy B

    2007-01-01

    This paper presents a two-phase cooling method using R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PE) such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles (HEVs). The cooling method involves submerging PE devices in an R134a bath, which limits the junction temperature of PE devices while conserving weight and volume of the heat sink without sacrificing equipment reliability. First, experimental tests that included an extended soak for more than 300 days were performed on a submerged IGBT and gate-controller card to study dielectric characteristics, deterioration effects, and heat flux capability of R134a. Results from these tests illustrate that R134a has high dielectric characteristics, no deterioration on electrical components, and a heat flux of 114 W/cm 2 for the experimental configuration. Second, experimental tests that included simultaneous operation with a mock automotive air-conditioner (A/C) system were performed on the same IGBT and gate controller card. Data extrapolation from these tests determined that a typical automotive A/C system has more than sufficient cooling capacity to cool a typical 30 kW traction inverter. Last, a discussion and simulation of active cooling of the IGBT junction layer with R134a refrigerant is given. This technique will drastically increase the forward current ratings and reliability of the PE device

  17. Parametric decay of an electromagnetic wave near electron cyclotron harmonics

    SciTech Connect

    Istomin, Y.N.; Leyser, T.B.

    1995-06-01

    A system of equations describing the nonlinear coupling of high frequency electron Bernstein (EB) and upper hybrid (UH) waves near harmonics of the electron cyclotron frequency with low frequency lower hybrid (LH) waves in a homogeneous, weakly magnetized, and weakly collisional plasma is derived. The EB and UH modes are described by a single second order equation, taking into account the interaction with low frequency density fluctuations. The ponderomotive force of the high frequency oscillations increases near the cyclotron harmonics due to the resonance with the electron motion. The obtained equations are used to study the parametric decay of an infinite wavelength electromagnetic pump wave into EB or UH waves and LH waves. The threshold electric fields are sufficiently low to be exceeded in high frequency ionospheric modification experiments. However, the instability cannot be excited for pump frequencies near the cyclotron harmonics. For the decay into EB waves, the resulting forbidden frequency range depends on the harmonic number in a power law manner, consistent with observations of stimulated electromagnetic emissions in ionospheric modification experiments. Further, for sufficiently high pump electric fields the instability is also suppressed, when the frequency mismatch around the eigenfrequencies at which the interaction can occur is of the order of the frequency separation between the EB and UH modes near the cyclotron harmonics. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  18. The development of advanced cooling methods for high-power electronics

    NASA Astrophysics Data System (ADS)

    Bland, T. J.; Ciaccio, M. P.; Downing, R. S.; Smith, W. G.

    1990-10-01

    Consideration is given to various technologies developed to meet the difficult cooling requirements of high-density power electronics equipment for the aerospace industry. Topics discussed include liquid impingement cooling, compact high-density cooler, integrally cooled semiconductor, high heat flux 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 electronic reliabilities using high-conductance cooling approaches.

  19. Cold electron sources using laser-cooled atoms

    NASA Astrophysics Data System (ADS)

    McCulloch, Andrew J.; Sparkes, Ben M.; Scholten, Robert E.

    2016-08-01

    Since the first observation of electron diffraction in 1927, electrons have been used to probe the structure of matter. High-brightness sources of thermal electrons have recently emerged that are capable of simultaneously providing high spatial resolving power along with ultrafast temporal resolution, however they are yet to demonstrate the holy grail of single-shot diffraction of non-crystalline objects. The development of the cold atom electron source, based around the ionisation of laser cooled atoms, has the potential to contribute to this goal. Electron generation from laser cooled atoms is in its infancy, but in just ten years has moved from a proposal to a source capable of performing single-shot diffraction imaging of crystalline structures. The high brightness, high transverse coherence length, and small energy spread of cold electron sources are also potentially advantageous for applications ranging from seeding of x-ray free-electron lasers and synchrotrons to coherent diffractive imaging and microscopy. In this review we discuss the context which motivates the development of these sources, the operating principles of the source, and recent experimental results. The achievements demonstrated thus far combined with theoretical proposals to alleviate current bottlenecks in development promise a bright future for these sources.

  20. Analysis and simulation for laser-Compton cooling of electron beams

    SciTech Connect

    Ohgaki, T.

    1999-10-01

    The method of the Laser-Compton cooling of the electron beams is studied. Using a Monte Carlo code, we have evaluated the effects of the Laser-electron interaction for cooling. The optics with and without chromatic correction for cooling are examined. Problems of the optics for cooling are discussed.

  1. A Project for synchrotron with electron cooling for cancer therapy

    NASA Astrophysics Data System (ADS)

    Vostrikov, V. A.; Kiselev, V. A.; Levichev, E. B.; Parkhomchuk, V. V.; Reva, V. B.; Sinyatkin, S.

    2012-07-01

    A project for a new generation of proton and ion accelerator facilities for cancer therapy has been developed at the Budker Institute of Nuclear Physics (BINP), Siberian Branch, Russian Academy of Sciences (SB RAS). This facility includes an electrostatic injector, a booster with a 10-Hz repetition rate, and a main synchrotron with electron cooling and beam transport lines for delivering the beam to treatment rooms. The application of electron cooling makes it possible to increase the beam intensity and reduce the apertures of both the synchrotron and the high-energy transport lines, as well as save construction costs and energy consumption as required by the accelerator complex. This paper describes the main features of the synchrotron and the requirements for its main systems and their parameters.

  2. ELECTRON HOLOGRAPHY OF ELECTROMAGNETIC FIELDS - RECENT THEORETICAL ADVANCES.

    SciTech Connect

    BELEGGIA,M.; POZZI, G.; TONOMURA, A.

    2007-01-01

    It has been shown in this work that the Fourier space approach can be fruitfully applied to the calculation of the fields and the associated electron optical phase shift of several magnetic and electrostatic structures, like superconducting vortices in conventional and high-T{sub c} superconductors, reverse biased p-n junctions, magnetic domains and nanoparticles. In all these cases, this novel approach has led to unexpected but extremely interesting results, very often expressed in analytical form, which allow the quantitative and reliable interpretation of the experimental data collected by means of electron holography or of more conventional Lorentz microscopy techniques. Moreover, it is worth recalling that whenever long-range electromagnetic fields are involved, a physical model of the object under investigation is necessary in order to take into account correctly the perturbation of the reference wave induced by the tail of the field protruding into the vacuum. For these reasons, we believe that the Fourier space approach for phase computations we have introduced and discussed in this chapter will represent an invaluable tool for the investigation of electromagnetic fields at the meso- and nano-scale.

  3. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    DOE PAGES

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motionmore » of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.« less

  4. Nonlinear Electromagnetic Waves in a Degenerate Electron-Positron Plasma

    NASA Astrophysics Data System (ADS)

    El-Labany, S. K.; El-Taibany, W. F.; El-Samahy, A. E.; Hafez, A. M.; Atteya, A.

    2015-08-01

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed.

  5. Resonance of relativistic electrons with electromagnetic ion cyclotron waves

    SciTech Connect

    Denton, R. E.; Jordanova, V. K.; Bortnik, J.

    2015-06-29

    Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron EMIC waves if the total density is large. We show that, for a particular EMIC mode, this dependence is weak due to the dependence of the wave frequency and wave vector on the density. A significant increase in relativistic electron minimum resonant energy might occur for the H band EMIC mode only for small density, but no changes in parameters significantly decrease the minimum resonant energy from a nominal value. The minimum resonant energy depends most strongly on the thermal velocity associated with the field line motion of the hot ring current protons that drive the instability. High density due to a plasmasphere or plasmaspheric plume could possibly lead to lower minimum resonance energy by causing the He band EMIC mode to be dominant. We demonstrate these points using parameters from a ring current simulation.

  6. Jumping-droplet electronics hot-spot cooling

    DOE PAGES

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; ...

    2017-03-20

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobicmore » surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.« less

  7. Precipitation of Relativistic Electrons by Electromagnetic Ion Cyclotron (EMIC) Waves

    NASA Astrophysics Data System (ADS)

    Denton, R. E.

    2015-12-01

    We use the electromagnetic ion cyclotron (EMIC) wave fields produced in a two dimensional hybrid code simulation (full dynamics particle ions, but inertialess fluid electrons) in dipole geometry in order to investigate the effect of magnetospheric EMIC waves on relativistic electrons. The plane of the simulation includes variation in the L shell direction and along magnetic field lines. Relativistic test particle electrons are inserted into the simulation when the wave fields are near their maximum amplitude. These electrons can be scattered into the loss cone so that they precipitate into the ionosphere. We find the effective pitch angle diffusion coefficient and probability of precipitation using these test particles. The pitch angle diffusion coefficients are largest for relativistic energies greater than 2 MeV, though they may be substantial for lower energies. The probability of precipitation is highest for low energy particles at small initial equatorial pitch angle. For high initial equatorial pitch angles, the probability of precipitation increases greatly with respect to particle energy. Starting from an isotropic pitch angle distribution of relativistic electrons with a Gaussian spread in the relativistic momentum, we find only a small drop in the probability of precipitation during 13 s time as the particle energy decreases. But that result depends on the initial pitch angle distribution. Starting with a distribution of particles steeply peaked at 90° initial equatorial pitch angle, the probability of precipitation would be greater for high-energy particles. We will discuss the mechanism of pitch angle scattering.

  8. High power electronic devices cooling at minimum ventilation power

    NASA Astrophysics Data System (ADS)

    Fabbri, Giampietro

    2008-01-01

    In the present work, the cooling of a high power electronic device is studied. The device is in contact with a heat dissipator crossed by air. The air motion through the dissipator is forced by a fan whose supplied power is to be minimized. A finite element dynamic model of the dissipator is firstly created, taking geometrical and physical properties into account as well as steady state experimental data. A simplified model is then obtained, which reproduces the time pattern of the maximum dissipator temperature as a response of the thermal flux removed from the electronic device and the mass flow rate of the air. Afterwards, the simplified model is utilized to build a control system which allows the electronic device to be correctly cooled at minimum air ventilation power during transition to steady states. Genetic algorithms are used to find the parameters of the finite element model and of the control system. Some functioning conditions of the electronic device are lastly considered and discussed.

  9. Electron guns and collectors developed at INP for electron cooling devices

    SciTech Connect

    Sharapa, A.N.; Shemyakin, A.V.

    1997-09-01

    Institute of Nuclear Physics (INP) has a rich experience in designing electron guns and collectors for electron cooling devices. This paper is a review of the experience of several INP research groups in this field. Some results obtained at INP for systems without a guiding magnetic field are also discussed.

  10. Cooled electronic system with thermal spreaders coupling electronics cards to cold rails

    DOEpatents

    Chainer, Timothy J; Gaynes, Michael A; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Schultz, Mark D; Simco, Daniel P; Steinke, Mark E

    2013-07-23

    Liquid-cooled electronic systems are provided which include an electronic assembly having an electronics card and a socket with a latch at one end. The latch facilitates securing of the card within the socket or removal of the card from the socket. A liquid-cooled cold rail is disposed at the one end of the socket, and a thermal spreader couples the electronics card to the cold rail. The thermal spreader includes first and second thermal transfer plates coupled to first and second surfaces on opposite sides of the card, and thermally conductive extensions extending from end edges of the plates, which couple the respective transfer plates to the liquid-cooled cold rail. The thermally conductive extensions are disposed to the sides of the latch, and the card is securable within or removable from the socket using the latch without removing the cold rail or the thermal spreader.

  11. Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

    PubMed

    Harris, C; Boivin, W; Boyd, S; Coletta, J; Kerr, L; Kempa, K; Aronow, S

    2000-01-01

    Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms

  12. Electromagnetic Waves and Bursty Electron Acceleration: Implications from Freja

    NASA Technical Reports Server (NTRS)

    Andersson, Laila; Ivchenko, N.; Wahlund, J.-E.; Clemmons, J.; Gustavsson, B.; Eliasson, L.

    2000-01-01

    Dispersive Alfven wave activity is identified in four dayside auroral oval events measured by the Freja satellite. The events are characterized by ion injection, bursty electron precipitation below about I keV, transverse ion heating and broadband extremely low frequency (ELF) emissions below the lower hybrid cutoff frequency (a few kHz). The broadband emissions are observed to become more electrostatic towards higher frequencies. Large-scale density depletions/cavities, as determined by the Langmuir probe measurements, and strong electrostatic emissions are often observed simultaneously. A correlation study has been carried out between the E- and B-field fluctuations below 64 Hz (the dc instrument's upper threshold) and the characteristics of the precipitating electrons. This study revealed that the energization of electrons is indeed related to the broadband ELF emissions and that the electrostatic component plays a predominant role during very active magnetospheric conditions. Furthermore, the effect of the ELF electromagnetic emissions on the larger scale field-aligned current systems has been investigated, and it is found that such an effect cannot be detected. Instead, the Alfvenic activity creates a local region of field-aligned currents. It is suggested that dispersive Alfven waves set up these local field-aligned current regions and in turn trigger more electrostatic emissions during certain conditions. In these regions ions are transversely heated, and large-scale density depletions/cavities may be created during especially active periods.

  13. Nonlinear Generation of Electromagnetic Waves Through Scattering by Thermal Electrons

    NASA Astrophysics Data System (ADS)

    Tejero, E. M.; Crabtree, C. E.; Blackwell, D. D.; Amatucci, B.; Mithaiwala, M.; Rudakov, L.; Ganguli, G.

    2014-12-01

    Nonlinear interactions involving whistler wave turbulence are important contributors to radiation belt dynamics, including the acceleration and loss of trapped electrons. Given sufficient whistler energy density, nonlinear scattering from thermal electrons can substantially change the wave normal angle, while inducing a small frequency shift [Ganguli et al., 2010]. This nonlinear process is being studied in the NRL Space Physics Simulation Chamber (SPSC) in scaled magnetospheric conditions. The plasma response as a function of transmitted lower hybrid wave amplitude is monitored with magnetic loop antennas. Measurements of the magnetic field vectors for the pump and daughter waves allow for the determination of wave distribution functions, which indicate the power distribution as a function of wave-normal angle and azimuthal angle. The wave distribution functions measured in the experiment demonstrate a dramatic change in propagation direction when the launched wave amplitude exceeds a small threshold (δB / B ~ 4 × 10-7). The experimental results support the theory of electromagnetic whistler wave generation through nonlinear scattering of electrostatic lower hybrid waves by thermal electrons in the Earth's magnetosphere [Crabtree et al, 2012].

  14. 49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section 236.8 Transportation Other Regulations Relating to... characteristics of electromagnetic, electronic, or electrical apparatus. Signal apparatus, the functioning...

  15. 49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section 236.8 Transportation Other Regulations Relating to... characteristics of electromagnetic, electronic, or electrical apparatus. Signal apparatus, the functioning...

  16. 49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section 236.8 Transportation Other Regulations Relating to... characteristics of electromagnetic, electronic, or electrical apparatus. Signal apparatus, the functioning...

  17. 49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section 236.8 Transportation Other Regulations Relating to... characteristics of electromagnetic, electronic, or electrical apparatus. Signal apparatus, the functioning...

  18. 49 CFR 236.8 - Operating characteristics of electromagnetic, electronic, or electrical apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section 236.8 Transportation Other Regulations Relating to... characteristics of electromagnetic, electronic, or electrical apparatus. Signal apparatus, the functioning...

  19. Ionospheric electron acceleration by electromagnetic waves near regions of plasma resonances

    NASA Astrophysics Data System (ADS)

    Villalon, Elena

    1989-03-01

    Electron acceleration by electromagnetic fields propagating in the inhomogeneous ionospheric plasma is investigated. It is found that high-amplitude short wavelength electrostatic waves are generated by the incident electromagnetic fields that penetrate the radio window. These waves can very efficiently transfer their energy to the electrons if the incident frequency is near the second harmonic of the cyclotron frequency.

  20. Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers

    NASA Technical Reports Server (NTRS)

    Skalare, Anders; McGrath, William; Bumble, Bruce; LeDuc, Henry

    2004-01-01

    A batch of experimental diffusion-cooled hot-electron bolometers (HEBs), suitable for use as mixers having input frequencies in the terahertz range and output frequencies up to about a gigahertz, exploit the superconducting/normal-conducting transition in a thin strip of tantalum. The design and operation of these HEB mixers are based on mostly the same principles as those of a prior HEB mixer that exploited the superconducting/normal- conducting transition in a thin strip of niobium and that was described elsewhere.

  1. Air Cooling for High Temperature Power Electronics (Presentation)

    SciTech Connect

    Waye, S.; Musselman, M.; King, C.

    2014-09-01

    Current emphasis on developing high-temperature power electronics, including wide-bandgap materials such as silicon carbide and gallium nitride, increases the opportunity for a completely air-cooled inverter at higher powers. This removes the liquid cooling system for the inverter, saving weight and volume on the liquid-to-air heat exchanger, coolant lines, pumps, and coolant, replacing them with just a fan and air supply ducting. We investigate the potential for an air-cooled heat exchanger from a component and systems-level approach to meet specific power and power density targets. A proposed baseline air-cooled heat exchanger design that does not meet those targets was optimized using a parametric computational fluid dynamics analysis, examining the effects of heat exchanger geometry and device location, fixing the device heat dissipation and maximum junction temperature. The CFD results were extrapolated to a full inverter, including casing, capacitor, bus bar, gate driver, and control board component weights and volumes. Surrogate ducting was tested to understand the pressure drop and subsequent system parasitic load. Geometries that met targets with acceptable loads on the system were down-selected for experimentation. Nine baseline configuration modules dissipated the target heat dissipation, but fell below specific power and power density targets. Six optimized configuration modules dissipated the target heat load, exceeding the specific power and power density targets. By maintaining the same 175 degrees C maximum junction temperature, an optimized heat exchanger design and higher device heat fluxes allowed a reduction in the number of modules required, increasing specific power and power density while still maintaining the inverter power.

  2. Electromagnetic compatibility of electronic implants--review of the literature.

    PubMed

    Kainz, W; Neubauer, G; Alesch, F; Schmid, G; Jahn, O

    2001-12-17

    The aim of the article was to provide an overview of published studies regarding the electromagnetic compatibility (EMC) of electronic implants. The available literature was sorted according to combinations of implant types and sources of interference. Several experiments concerning the susceptibility of pacemakers to mobile phones have been performed. The results of these experiments suggest measures that may be used to prevent the disturbance of pacemakers. For instance, instead of carrying the activated mobile phone in the breast pocket it is recommended that a distance of 30 cm be maintained between the pacemaker and the mobile phone, and that the mobile phone be used on the contralateral side of the pacemaker's location. Similar measures may be recommended for patients with implantable cardioverter defibrillators when using mobile phones. Patients with electronic implants should walk rapidly through anti theft-devices because some of these devices are liable to disturb implants. Patients with cardiac pacemakers should not be subjected to magnetic resonance imaging as far as possible. For a variety of combinations of implants and interference sources, e.g. cardiac pacemakers and base station antennas, no studies were found in the literature. It is strongly recommended that trials be carried out to evaluate the potential risk for patients in these settings.

  3. Thermoelectric-enhanced, liquid-based cooling of a multi-component electronic system

    DOEpatents

    Chainer, Timothy J; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2015-11-10

    Methods are provided for facilitating cooling of an electronic component. The methods include providing: a liquid-cooled structure, a thermal conduction path coupling the electronic component and the liquid-cooled structure, a coolant loop in fluid communication with a coolant-carrying channel of the liquid-cooled structure, and an outdoor-air-cooled heat exchange unit coupled to facilitate heat transfer from the liquid-cooled structure via, at least in part, the coolant loop. The thermoelectric array facilitates transfer of heat from the electronic component to the liquid-cooled structure, and the heat exchange unit cools coolant passing through the coolant loop by dissipating heat from the coolant to outdoor ambient air. In one implementation, temperature of coolant entering the liquid-cooled structure is greater than temperature of the outdoor ambient air to which heat is dissipated.

  4. Thermoelectric-enhanced, liquid-based cooling of a multi-component electronic system

    DOEpatents

    Chainer, Timothy J; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Schmidt, Roger R; Steinke, Mark E

    2015-05-12

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled structure, a thermal conduction path coupling the electronic component and the liquid-cooled structure, a coolant loop in fluid communication with a coolant-carrying channel of the liquid-cooled structure, and an outdoor-air-cooled heat exchange unit coupled to facilitate heat transfer from the liquid-cooled structure via, at least in part, the coolant loop. The thermoelectric array facilitates transfer of heat from the electronic component to the liquid-cooled structure, and the heat exchange unit cools coolant passing through the coolant loop by dissipating heat from the coolant to outdoor ambient air. In one implementation, temperature of coolant entering the liquid-cooled structure is greater than temperature of the outdoor ambient air to which heat is dissipated.

  5. Properties of electrons scattered by a strong plane electromagnetic wave with a linear polarization: Semiclassical treatment

    NASA Astrophysics Data System (ADS)

    Bogdanov, O. V.; Kazinski, P. O.

    2015-02-01

    The problem of scattering of ultrarelativistic electrons by a strong plane electromagnetic wave of a low (optical) frequency and linear polarization is solved in the semiclassical approximation, when the electron wave packet size is much smaller than the wavelength of electromagnetic wave. The exit momenta of ultrarelativistic electrons scattered are found using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of electrons traversed the electromagnetic wave depend weakly on the initial values of momenta. These electrons are mostly scattered at small angles to the propagation direction of the electromagnetic wave. The maximum Lorentz factor of electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momentum. The momentum component parallel to the electric field vector of the electromagnetic wave is determined solely by the laser beam diameter measured in the units of the classical electron radius. As for the reflected electrons, they for the most part lose the energy, but remain relativistic. A reflection law that relates the incident and reflection angles and is independent of any parameters is found.

  6. 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.

  7. Electron Weibel Instability Mediated Laser Driven Electromagnetic Collisionless Shock

    NASA Astrophysics Data System (ADS)

    Jia, Qing; Mima, Kunioki; Cai, Hong-Bo; Taguchi, Toshihiro; Nagatomo, Hideo; He, X. T.

    2015-11-01

    As a fundamental nonlinear structure, collisionless shock is widely studied in astrophysics. Recently, the rapidly-developing laser technology provides a good test-bed to study such shock physics in laboratory. In addition, the laser driven shock ion acceleration is also interested due to its potential applications. We explore the effect of external parallel magnetic field on the collisionless shock formation and resultant particle acceleration by using the 2D3V PIC simulations. We show that unlike the electrostatic shock generated in the unmagnetized plasma, the shock generated in the weakly-magnetized laser-driven plasma is mostly electromagnetic (EM)-like with higher Mach number. The generation mechanism is due to the stronger transverse magnetic field self-generated at the nonlinear stage of the electron Weibel instability which drastically scatters particles and leads to higher energy dissipation. Simulation results also suggest more ions are reflected by this EM shock and results in larger energy transfer rate from the laser to ions, which is of advantage for applications such as neutron production and ion fast ignition.

  8. Thermal transfer structures coupling electronics card(s) to coolant-cooled structure(s)

    DOEpatents

    David, Milnes P; Graybill, David P; Iyengar, Madhusudan K; Kamath, Vinod; Kochuparambil, Bejoy J; Parida, Pritish R; Schmidt, Roger R

    2014-12-16

    Cooling apparatuses and coolant-cooled electronic systems are provided which include thermal transfer structures configured to engage with a spring force one or more electronics cards with docking of the electronics card(s) within a respective socket(s) of the electronic system. A thermal transfer structure of the cooling apparatus includes a thermal spreader having a first thermal conduction surface, and a thermally conductive spring assembly coupled to the conduction surface of the thermal spreader and positioned and configured to reside between and physically couple a first surface of an electronics card to the first surface of the thermal spreader with docking of the electronics card within a socket of the electronic system. The thermal transfer structure is, in one embodiment, metallurgically bonded to a coolant-cooled structure and facilitates transfer of heat from the electronics card to coolant flowing through the coolant-cooled structure.

  9. Electromagnetic Radiation System (EMRS) for Susceptibility Testing.

    DTIC Science & Technology

    ELECTROMAGNETIC COMPATIBILITY, *ELECTROMAGNETIC SUSCEPTIBILITY, COMMUNICATION EQUIPMENT, ELECTRONIC EQUIPMENT, ELECTROMAGNETIC RADIATION , ANTENNAS, ELECTROMAGNETIC INTERFERENCE, RADAR SIGNALS, RADIO SIGNALS, FIELD INTENSITY.

  10. Modeling Single-Phase and Boiling Liquid Jet Impingement Cooling in Power Electronics

    SciTech Connect

    Narumanchi, S. V. J.; Hassani, V.; Bharathan, D.

    2005-12-01

    Jet impingement has been an attractive cooling option in a number of industries over the past few decades. Over the past 15 years, jet impingement has been explored as a cooling option in microelectronics. Recently, interest has been expressed by the automotive industry in exploring jet impingement for cooling power electronics components. This technical report explores, from a modeling perspective, both single-phase and boiling jet impingement cooling in power electronics, primarily from a heat transfer viewpoint. The discussion is from the viewpoint of the cooling of IGBTs (insulated-gate bipolar transistors), which are found in hybrid automobile inverters.

  11. Heating and cooling of a two-dimensional electron gas by terahertz radiation

    SciTech Connect

    Budkin, G. V.; Tarasenko, S. A.

    2011-04-15

    The absorption of terahertz radiation by free charge carriers in n-type semiconductor quantum wells accompanied by the interaction of electrons with acoustic and optical phonons is studied. It is shown that intrasubband optical transitions can cause both heating and cooling of the electron gas. The cooling of charge carriers occurs in a certain temperature and radiation frequency region where light is most efficiently absorbed due to intrasubband transitions with emission of optical phonons. In GaAs quantum wells, the optical cooling of electrons occurs most efficiently at liquid nitrogen temperatures, while cooling is possible even at room temperature in GaN heterostructures.

  12. Commissioning of Fermilab's electron cooling system for 8-GeV antiprotons

    SciTech Connect

    Nagaitsev, S.; Broemmelsiek, D.; Burov, A.; Carlson, K.; Gattuso, C.; Hu, M.; Kramper, B.; Kroc, T.; Leibfritz, J.; Prost, L.; Pruss, S.; Saewert, G.; Schmidt, C.W.; Shemyakin, A.; Sutherland, M.; Tupikov, V.; Warner, A.; Seletsky, S.; Gai, W.; Kazakevich, Grigory M.; /Novosibirsk, IYF

    2005-05-01

    A 4.3-MeV electron cooling system [1] has been installed at Fermilab in the Recycler antiproton storage ring and is currently being commissioned. The cooling system is designed to assist accumulation of 8.9-GeV/c antiprotons for the Tevatron collider operations. This paper reports on the progress of the electron beam commissioning effort as well as on detailed plans of demonstrating the cooling of antiprotons.

  13. Spray cooling characteristics of nanofluids for electronic power devices

    NASA Astrophysics Data System (ADS)

    Hsieh, Shou-Shing; Leu, Hsin-Yuan; Liu, Hao-Hsiang

    2015-03-01

    The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle volume fraction and mass flow rate of the liquid on the surface heat flux, including critical heat flux (CHF), are explored. Both steady state and transient data are collected for the two-phase heat transfer coefficient, boiling curve/ cooling history, and the corresponding CHF. The heat transfer removal rate can reach up to 274 W/cm2 with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10-4 kg/cm2s.

  14. Spray cooling characteristics of nanofluids for electronic power devices.

    PubMed

    Hsieh, Shou-Shing; Leu, Hsin-Yuan; Liu, Hao-Hsiang

    2015-01-01

    The performance of a single spray for electronic power devices using deionized (DI) water and pure silver (Ag) particles as well as multi-walled carbon nanotube (MCNT) particles, respectively, is studied herein. The tests are performed with a flat horizontal heated surface using a nozzle diameter of 0.5 mm with a definite nozzle-to-target surface distance of 25 mm. The effects of nanoparticle volume fraction and mass flow rate of the liquid on the surface heat flux, including critical heat flux (CHF), are explored. Both steady state and transient data are collected for the two-phase heat transfer coefficient, boiling curve/ cooling history, and the corresponding CHF. The heat transfer removal rate can reach up to 274 W/cm(2) with the corresponding CHF enhancement ratio of 2.4 for the Ag/water nanofluids present at a volume fraction of 0.0075% with a low mass flux of 11.9 × 10(-4) kg/cm(2)s.

  15. Electron cooling of 8-GeV antiprotons at Fermilab's Recycler: Results and operational implications

    SciTech Connect

    Prost, L.R.; Broemmelsiek, D.; Burov, Alexey V.; Carlson, K.; Gattuso, C.; Hu, M.; Kroc, T.; Leibfritz, J.; Nagaitsev, S.; Pruss, S.; Saewert, G.; Schmidt, C.W.; Shemyakin, A.; Sutherland, M.; Tupikov, V.; Warner, A.; /Fermilab

    2006-05-01

    Electron cooling of 8 GeV antiprotons at Fermilab's Recycler storage ring is now routinely used in the collider operation. It requires a 0.1-0.5 A, 4.3 MeV dc electron beam and is designed to increase the longitudinal phase-space density of the circulating antiproton beam. This paper briefly describes the characteristics of the electron beam that were achieved to successfully cool antiprotons. Then, results from various cooling force measurements along with comparison to a nonmagnetized model are presented. Finally, operational aspects of the implementation of electron cooling at the Recycler are discussed, such as adjustments to the cooling rate and the influence of the electron beam on the antiproton beam lifetime.

  16. Advanced Electron Holography Applied to Electromagnetic Field Study in Materials Science.

    PubMed

    Shindo, Daisuke; Tanigaki, Toshiaki; Park, Hyun Soon

    2016-11-17

    Advances and applications of electron holography to the study of electromagnetic fields in various functional materials are presented. In particular, the development of split-illumination electron holography, which introduces a biprism in the illumination system of a holography electron microscope, enables highly accurate observations of electromagnetic fields and the expansion of the observable area. First, the charge distributions on insulating materials were studied by using split-illumination electron holography and including a mask in the illumination system. Second, the three-dimensional spin configurations of skyrmion lattices in a helimagnet were visualized by using a high-voltage holography electron microscope. Third, the pinning of the magnetic flux lines in a high-temperature superconductor YBa2 Cu3 O7-y was analyzed by combining electron holography and scanning ion microscopy. Finally, the dynamic accumulation and collective motions of electrons around insulating biomaterial surfaces were observed by utilizing the amplitude reconstruction processes of electron holography.

  17. Efficient regime of electromagnetic emission in a plasma with counterstreaming electron beams

    SciTech Connect

    Timofeev, I. V.; Annenkov, V. V.

    2014-08-15

    Efficiency of electromagnetic emission produced in a magnetized plasma with counterstreaming electron beams was investigated using both the linear kinetic theory and particle-in-cell simulations. We calculated the growth rate of the beam-plasma instability taking into account both kinetic and relativistic effects and showed that there exists a regime in which transversely propagating electromagnetic waves can be generated by the coupling of the most unstable oblique beam-driven modes. It was confirmed by numerical simulations that such a tune-up of system parameters for a specific nonlinear process can lead to a substantial increase in electromagnetic emission efficiency. It was found that electromagnetic radiation emerging from the plasma in such a regime is generated near the harmonics of the pump frequency that is determined by the typical eigenfrequency of the beam-driven modes. It was also shown that the peak emission power can reach 5% of the maximal power lost by beam electrons.

  18. Electromagnetic radiation and nonlinear energy flow in an electron beam-plasma system

    NASA Technical Reports Server (NTRS)

    Whelan, D. A.; Stenzel, R. L.

    1985-01-01

    It is shown that the unstable electron-plasma waves of a beam-plasma system can generate electromagnetic radiation in a uniform plasma. The generation mechanism is a scattering of the unstable electron plasma waves off ion-acoustic waves, producing electromagnetic waves whose frequency is near the local plasma frequency. The wave vector and frequency matching conditions of the three-wave mode coupling are experimentally verified. The electromagnetic radiation is observed to be polarized with the electric field parallel to the beam direction, and its source region is shown to be localized to the unstable plasma wave region. The frequency spectrum shows negligible intensity near the second harmonic of the plasma frequency. These results suggest that the observed electromagnetic radiation of type III solar bursts may be generated near the local plasma frequency and observed downstream where the wave frequency is near the harmonic of the plasma frequency.

  19. Smart interactive electronic system for monitoring the electromagnetic activities of biological systems

    NASA Astrophysics Data System (ADS)

    Popa, Sorin G.; Shahinpoor, Mohsen

    2001-08-01

    A novel electronic device capable of sensing and monitoring the myoelectric, polarization wave and electromagnetic activities of the biological systems and in particular the human body is presented. It is known that all the physical and chemical processes within biological systems are associated with polarization, depolarization waves from the brain, neural signals and myoelectric processes that manifest themselves in ionic and dipole motion. The technology developed in our laboratory is based on certain charge motion sensitive electronics. The electronic system developed is capable of sensing the electromagnetic activities of biological systems. The information obtained is then processed by specialized software in order to interpret it from physical and chemical point of view.

  20. A robust platform cooled by superconducting electronic refrigerators

    SciTech Connect

    Nguyen, H. Q.; Meschke, M.; Pekola, J. P.

    2015-01-05

    A biased tunnel junction between a superconductor and a normal metal can cool the latter electrode. Based on a recently developed cooler with high power and superior performance, we have integrated it with a dielectric silicon nitride membrane, and cooled phonons from 305 mK down to 200 mK. Without perforation and covered under a thin alumina layer, the membrane is rigorously transformed into a cooling platform that is robust and versatile for multiple practical purposes. We discussed our results and possibilities to further improve the device.

  1. Decontamination in the Electron Probe Microanalysis with a Peltier-Cooled Cold Finger.

    PubMed

    Buse, Ben; Kearns, Stuart; Clapham, Charles; Hawley, Donovan

    2016-10-01

    A prototype Peltier thermoelectric cooling unit has been constructed to cool a cold finger on an electron microprobe. The Peltier unit was tested at 15 and 96 W, achieving cold finger temperatures of -10 and -27°C, respectively. The Peltier unit did not adversely affect the analytical stability of the instrument. Heat conduction between the Peltier unit mounted outside the vacuum and the cold finger was found to be very efficient. Under Peltier cooling, the vacuum improvement associated with water vapor deposition was not achieved; this has the advantage of avoiding severe degradation of the vacuum observed when warming up a cold finger from liquid nitrogen (LN2) temperatures. Carbon contamination rates were reduced as cooling commenced; by -27°C contamination rates were found to be comparable with LN2-cooled devices. Peltier cooling, therefore, provides a viable alternative to LN2-cooled cold fingers, with few of their associated disadvantages.

  2. Single pass electron beam cooling of gold ions between EBIS LINAC and booster is theoretically possible!

    SciTech Connect

    Hershcovitch, A.

    2011-01-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Many issues, regarding a low energy high current electron beam that is needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, were examined. Computations and some experimental data indicate that none of these issues is a show stopper. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in about one meter. Hence, this option cooling deserves further more serious considerations.

  3. SRF photoinjector for proof-of-principle experiment of coherent electron cooling at RHIC

    SciTech Connect

    Kayran D.; Belomestnykh, S.; Ben-Zvi, I.; Brutus, J.C.; et al

    2012-05-20

    Coherent Electron Cooling (CEC) based on Free Electron Laser (FEL) amplifier promises to be a very good way to cool protons and ions at high energies. A proof of principle experiment to demonstrate cooling at 40 GeV/u is under construction at BNL. One of possible sources to provide sufficient quality electron beam for this experiment is a SRF photoinjector. In this paper we discuss design and simulated performance of the photoinjector based on existing 112 MHz SRF gun and newly designed single-cavity SRF linac operating at 704 MHz.

  4. Micro-Stirling Active Cooling Module (MS/ACM) for DoD Electronics Systems

    DTIC Science & Technology

    2012-03-01

    Micro- Stirling Active Cooling Module (MS/ACM) for DoD Electronics Systems Douglas S. Beck Beck Engineering , Inc. 1490 Lumsden Road, Port Orchard...refrigerator. We are developing for DARPA a cm-scale Micro- Stirling Active Cooling Module (MS/ACM) micro- refrigerator to benefit the DoD systems. Under...a DARPA contract, we are designing, building, and demonstrating a breadboard MS/ACM. Keywords: Stirling ; cooler; active cooling module; micro

  5. Thermal management in high-power electronics cooled down using capillary pump

    NASA Astrophysics Data System (ADS)

    Wiecek, Boguslaw; Wajman, Tomasz; Felczak, Mariola; Berlinski, Marek

    2003-04-01

    By using the evaporation of working fluid in the capillary it is possible to design and build cooling device, with high cooling effectiveness. This paper presents a preliminary cooling system integrated with electronic device., which is supported by evaporation and capillarity effects. A simplified modeling of conjugate heat transfer including evaporation using FLUENT package is discussed. The experiments for open and close loop capillary pomp are shown to compare and verify the measurements and simulation results.

  6. Electromagnetic dispersion characteristics of a high energy electron beam guided with an ion channel

    NASA Astrophysics Data System (ADS)

    Jixiong, Xiao; Zhong, Zeng; Zhijiang, Wang; Donghui, Xia; Changhai, Liu

    2017-02-01

    Taking self-fields into consideration, dispersion properties of two types of electromagnetic modes for a high energy electron beam guided with an ion channel are investigated by using the linear perturbation theory. The dependences of the dispersion frequencies of electromagnetic waves on the electron beam radius, betatron frequency and boundary current are revealed. It is found that the electron beam radius and betatron frequency have different influences on the electromagnetic waves dispersion behavior by compared with the previous works. As the boundary current is taken into account, the TM modes will have two branches and a low-frequency branch emerged as the new branch in strong ion channel case. This new branch has similar dispersion behavior to the betatron modes. For TE modes, there are two branches and they have different dispersion behaviors in strong ion channel case. However, in weak ion channel case, the dispersion behaviors for both of the low frequency and high frequency branches are similar.

  7. EXTERNAL COMPTON EMISSION IN BLAZARS OF NONLINEAR SYNCHROTRON SELF-COMPTON-COOLED ELECTRONS

    SciTech Connect

    Zacharias, Michael; Schlickeiser, Reinhard E-mail: rsch@tp4.rub.de

    2012-12-20

    The origin of the high-energy component in spectral energy distributions (SEDs) of blazars is still something of a mystery. While BL Lac objects can be successfully modeled within the one-zone synchrotron self-Compton (SSC) scenario, the SED of low-peaked flat spectrum radio quasars is more difficult to reproduce. Their high-energy component needs the abundance of strong external photon sources, giving rise to stronger cooling via the inverse Compton (IC) channel, and thus to a powerful component in the SED. Recently, we have been able to show that such a powerful inverse Compton component can also be achieved within the SSC framework. This, however, is only possible if the electrons cool by SSC, which results in a nonlinear process, since the cooling depends on an energy integral over the electrons. In this paper, we aim to compare the nonlinear SSC framework with the external Compton (EC) output by calculating analytically the EC component with the underlying electron distribution being either linearly or nonlinearly cooled. Due to the additional linear cooling of the electrons with the external photons, higher number densities of electrons are required to achieve nonlinear cooling, resulting in more powerful IC components. If the electrons initially cool nonlinearly, the resulting SED can exhibit a dominant SSC over the EC component. However, this dominance depends strongly on the input parameters. We conclude that, with the correct time-dependent treatment, the SSC component should be taken into account in modeling blazar flares.

  8. Electrons in a relativistic-intensity laser field: generation of zeptosecond electromagnetic pulses and energy spectrum of the accelerated electrons

    SciTech Connect

    Andreev, A A; Galkin, A L; Kalashnikov, M P; Korobkin, V V; Romanovsky, Mikhail Yu; Shiryaev, O B

    2011-08-31

    We study the motion of an electron and emission of electromagnetic waves by an electron in the field of a relativistically intense laser pulse. The dynamics of the electron is described by the Newton equation with the Lorentz force in the right-hand side. It is shown that the electrons may be ejected from the interaction region with high energy. The energy spectrum of these electrons and the technique of using the spectrum to assess the maximal intensity in the focus are analysed. It is found that electromagnetic radiation of an electron moving in an intense laser field occurs within a small angle around the direction of the electron trajectory tangent. The tangent quickly changes its direction in space; therefore, electromagnetic radiation of the electron in the far-field zone in a certain direction in the vicinity of the tangent is a short pulse with a duration as short as zeptoseconds. The calculation of the temporary and spectral distribution of the radiation field is carried out. (superintense laser fields)

  9. Bulk and surface electromagnetic response of metallic metamaterials to convection electrons

    NASA Astrophysics Data System (ADS)

    So, Jin-Kyu; Jang, Kyu-Ha; Park, Gun-Sik; Garcia-Vidal, F. J.

    2011-08-01

    The electromagnetic response of three-dimensional metallic metamaterials with isotropic effective index of refraction to fast-moving electrons is studied by numerical simulations. The considered metamaterials can support Cerenkov radiation [P. A. Cherenkov, Dokl. Akad. Nauk SSSR 2, 451 (1934)], and their effective dielectric behavior is confirmed by the detailed angular dependence of the generated radiation cone on the kinetic energy of electrons. Moreover, in addition to the predicted bulk modes, surface electromagnetic excitation is observed in a specific type of metamaterials and its dispersion is sensitive to the thickness of the subwavelength rods.

  10. Enhanced electromagnetic emission from plasmas containing positive dust grains and electrons

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Shukla, Nitin; Stenflo, L.

    2007-05-01

    Large amplitude high-frequency (HF) electromagnetic (EM) waves can scatter off dust-acoustic waves in plasmas containing positive dust grains and electrons, and can thus be responsible for HF enhanced electromagnetic emissions (EEE). An expression for the ensemble average of the squared HF-EEE vector potential is therefore derived, following the standard parametric interaction formalism and adopting the Rostoker superposition principle. The results should be useful for deducing the dust plasma parameters (e.g. the dust number density and dust charge) in situ, and HF intense EM beams can thus be used for diagnosis of positive dust-electron plasmas in space and laboratories.

  11. Transverse Electron Cooling Measurements with a Kicked Pencil Beam in CELSIUS

    SciTech Connect

    Ziemann, Volker

    2005-06-08

    We report first results from measuring transverse cooling times by kicking the beam and then observing turn-by-turn beam positions which decay as a function of time. The measurements are done for several electron beam currents.

  12. Kinetic theory of the electron bounce instability in two dimensional current sheets—Full electromagnetic treatment

    SciTech Connect

    Tur, A.; Fruit, G.; Louarn, P.

    2014-03-15

    In the general context of understanding the possible destabilization of a current sheet with applications to magnetospheric substorms or solar flares, a kinetic model is proposed for studying the resonant interaction between electromagnetic fluctuations and trapped bouncing electrons in a 2D current sheet. Tur et al. [A. Tur et al., Phys. Plasmas 17, 102905 (2010)] and Fruit et al. [G. Fruit et al., Phys. Plasmas 20, 022113 (2013)] already used this model to investigate the possibilities of electrostatic instabilities. Here, the model is completed for full electromagnetic perturbations. Starting with a modified Harris sheet as equilibrium state, the linearized gyrokinetic Vlasov equation is solved for electromagnetic fluctuations with period of the order of the electron bounce period. The particle motion is restricted to its first Fourier component along the magnetic field and this allows the complete time integration of the non local perturbed distribution functions. The dispersion relation for electromagnetic modes is finally obtained through the quasineutrality condition and the Ampere's law for the current density. It is found that for mildly strechted current, undamped modes oscillate at typical electron bounce frequency with wavelength of the order of the plasma sheet half thickness. As the stretching of the plasma sheet becomes more intense, the frequency of these normal modes decreases and beyond a certain threshold in ε = B{sub z}/B{sub lobes}, the mode becomes explosive with typical growth rate of a few tens of seconds. The free energy contained in the bouncing motion of the electrons may trigger an electromagnetic instability able to disrupt the cross-tail current in a few seconds. This new instability–electromagnetic electron-bounce instability–may explain fast and global scale destabilization of current sheets as required to describe substorm phenomena.

  13. Fundamental studies in cryogenic cooling of power electronics

    NASA Astrophysics Data System (ADS)

    Chow, L. C.; Sehmbey, M. S.; Hahm, O. J.; Chui, C. J.

    1994-09-01

    This study details the results from experiments conducted to study the heat transfer characteristics during liquid nitrogen spray cooling and pool boiling from a heater array. Four different nozzles at various pressures were used to study the variation in spray cooling heat transfer at liquid nitrogen temperature. Effect of nozzle and flow rate on the critical heat flux and the heat transfer coefficient are presented. This study also provides empirical correlations for the spray cooling characteristics. The critical heat flux and the heat transfer coefficient have been correlated using nondimensional numbers. The study also shows the importance of surface roughness for spray cooling with liquid nitrogen. The rougher surfaces were shown to have significantly higher heat transfer rates and similar critical heat fluxes occurring at lower temperatures. The results from experiments conducted to study the pool boiling heat transfer from a vertical array with flush mounted heat sources are also presented. The lower heaters were found to enhance the heat transfer from the upper heaters due to bubble pumped convection.

  14. Experimental search for the electron electric dipole moment with laser cooled francium atoms

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Kawamura, H.; Uchiyama, A.; Aoki, T.; Asahi, K.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Nataraj, H. S.; Sato, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Yoshimi, A.; Sakemi, Y.

    2015-04-01

    A laser cooled heavy atom is one of the candidates to search for the permanent electric dipole moment (EDM) of the electron due to the enhancement mechanism and its long coherence time. The laser cooled francium (Fr) factory has been constructed to perform the electron EDM search at the Cyclotron and Radioisotope Center, Tohoku University. The present status of Fr production and the EDM measurement system is presented.

  15. Low material budget microfabricated cooling devices for particle detectors and front-end electronics

    NASA Astrophysics Data System (ADS)

    Mapelli, A.; Catinaccio, A.; Daguin, J.; van Lintel, H.; Nuessle, G.; Petagna, P.; Renaud, P.

    2011-06-01

    Novel cooling systems with very low material budget are being fabricated and studied. They consist of silicon wafers in which microchannels are etched and closed by bonding another wafer. This cooling option is being considered for future HEP detectors of the sLHC and linear colliders. It is currently under investigation as an option for the cooling of the NA62 Gigatracker silicon pixel detector and its front-end electronics where the microfabricated cooling plate would stand directly in the beam. In this particular case, microchannel cooling meets both the very aggressive X 0 (0.15%) specifications and the anticipated 2 W/cm 2 power dissipation by the active electronics.

  16. The integration of liquid cryogen cooling and cryocoolers withsuperconducting electronic systems

    SciTech Connect

    Green, Michael A.

    2003-07-09

    The need for cryogenic cooling has been a critical issuethat has kept superconducting electronic devices from reaching the marketplace. Even though the performance of many of the superconductingcircuits is superior to silicon electronics, the requirement forcryogenic cooling has put the superconducting devices at a seriousdisadvantage. This report discusses the process of refrigeratingsuperconducting devices with cryogenic liquids and small cryocoolers.Three types of cryocoolers are compared for vibration, efficiency, andreliability. The connection of a cryocooler to the load is discussed. Acomparison of using flexible copper straps to carry the heat load andusing heat pipe is shown. The type of instrumentation needed formonitoring and controlling the cooling is discussed.

  17. Use of LHP for cooling power electronic components

    NASA Astrophysics Data System (ADS)

    Smitka, M.; Malcho, M.; Nemec, P.; Kolková, Z.

    2013-04-01

    The paper deals with use of cooling equipment build on basis two phase thermosyphon loop. This device belongs to a group of loop heat pipe (LHP). This LHP is a two-phase device with extremely high effective thermal conductivity that utilizes the thermodynamic pressure difference to circulate fluid. It was invented in Russia in the early 1980´s. Thermosyphon loop is similar as LHP but it doesn't contain wick and circulation of the fluid using gravitation force instead of capillary pressure as it is in LHP. The work deals with the cooling insulated gate bipolar transistor with 370 W. The paper describes the course of the heat dissipation using ribbed cooler for natural convection and using fin for forced convection. The results are compared with heat dissipation through thermosyphon loop.

  18. Comparison of Hybrid Electric Vehicle Power Electronics Cooling Options

    SciTech Connect

    O'Keefe, M.; Bennion, K.

    2008-01-01

    This study quantifies the heat dissipation potential of three inverter package configurations over a range of control factors. These factors include coolant temperature, number of sides available for cooling, effective heat transfer coefficient, maximum semiconductor junction temperature, and interface material thermal resistance. Heat dissipation potentials are examined in contrast to a research goal to use 105..deg..C coolant and dissipate 200 W/cm2 heat across the insulated gate bipolar transistor and diode silicon area. Advanced double-sided cooling configurations with aggressive heat transfer coefficients show the possibility of meeting these targets for a 125..deg..C maximum junction temperature, but further investigation is needed. Even with maximum tolerable junction temperatures of 200..deg..C, effective heat transfer coefficients of 5,000 to 10,000 W/m2-K will be needed for coolant temperatures of 105..deg..C or higher.

  19. Interaction of Electrons and Electromagnetic Waves in Periodic Structures.

    DTIC Science & Technology

    1979-02-01

    electron guns and made appreciable progress in the construction of an experimental set- up for spontaneous and stimulated Cerenkov-Smith Purcell...design and initial fabrication of two versions of electron guns and made appreciable progress in the construction of an experimental set- up for...for the Cerenkov-Smith-Purcell j ,. -8-r radiation experimental set up . The system is a standard 14" diameter U.H.V. pump which was adapted to our

  20. The nonextensive parameter for nonequilibrium electron gas in an electromagnetic field

    SciTech Connect

    Yu, Haining; Du, Jiulin

    2014-11-15

    The nonextensive parameter for nonequilibrium electron gas of the plasma in an electromagnetic field is studied. We exactly obtained an expression of the q-parameter based on Boltzmann kinetic theories for plasmas, where Coulombian interactions and Lorentz forces play dominant roles. We show that the q-parameter different from unity is related by an equation to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the gas. The effect of the magnetic field on the q-parameter depends on the overall bulk velocity. Thus the q-parameter for the electron gas in an electromagnetic field represents the nonequilibrium nature or nonisothermal configurations of the plasma with electromagnetic interactions. - Highlights: • An expression of the q-parameter is obtained for nonequilibrium plasma with electromagnetic interactions. • The q-parameter is related to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the plasma. • The q-parameter represents the nonequilibrium nature of the complex plasma with electromagnetic interactions.

  1. Guiding and collimating fast electron beam by the quasi-static electromagnetic field array

    SciTech Connect

    Wang, J.; Zhao, Z. Q.; He, W. H.; Dong, K. G.; Wu, Y. C.; Zhu, B.; Zhang, T. K.; Zhang, B.; Zhang, Z. M.; Gu, Y. Q.; Cao, L. H.

    2014-10-15

    A guidance and collimation scheme for fast electron beam in a traverse periodic quasi-static electromagnetic field array is proposed with the semi-analytic method and the particle-in-cell simulation. The sheath electric fields on the surfaces of nanowires and the magnetic fields around the nanowires form a traverse periodic quasi-static electromagnetic field array. Therefore, most of the fast electrons are confined at the nanowire surfaces and transport forward. More importantly, due to the divergent property of the beams, the magnitudes of the generated fields decrease with the target depth. The lateral momenta of the electrons convert into the forward momenta through Lorenz force, and they cannot recover their initial values. Therefore, the fast electrons can be guided and collimated efficiently in the gaps between the nanowires. In our particle-in-cell simulations, the observed guiding efficiency exceeds 80% compared with the reference target.

  2. Electromagnetic waves destabilized by runaway electrons in near-critical electric fields

    SciTech Connect

    Komar, A.; Pokol, G. I.; Fueloep, T.

    2013-01-15

    Runaway electron distributions are strongly anisotropic in velocity space. This anisotropy is a source of free energy that may destabilize electromagnetic waves through a resonant interaction between the waves and the energetic electrons. In this work, we investigate the high-frequency electromagnetic waves that are destabilized by runaway electron beams when the electric field is close to the critical field for runaway acceleration. Using a runaway electron distribution appropriate for the near-critical case, we calculate the linear instability growth rate of these waves and conclude that the obliquely propagating whistler waves are most unstable. We show that the frequencies, wave numbers, and propagation angles of the most unstable waves depend strongly on the magnetic field. Taking into account collisional and convective damping of the waves, we determine the number density of runaways that is required to destabilize the waves and show its parametric dependences.

  3. Electromagnetic Interference Measurements in Electronic Voice Switching Equipment Areas.

    DTIC Science & Technology

    the Millville , NJ RCAG site, where components of the Electronic Voice Switching (EVS) system may be installed. Test areas included an EVS junction...module area, an EVS back room equipment area (both at the Denver ARTCC) and an EVS RCAG equipment area at the Millville , NJ site.

  4. Estimation of radiation effects in the front-end electronics of an ILC electromagnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Bartsch, V.; Postranecky, M.; Targett-Adams, C.; Warren, M.; Wing, M.

    2008-08-01

    The front-end electronics of the electromagnetic calorimeter of an International Linear Collider detector are situated in a radiation environment. This requires the effect of the radiation on the performance of the electronics, specifically FPGAs, to be examined. In this paper we study the flux, particle spectra and deposited doses at the front-end electronics of the electromagnetic calorimeter of a detector at the ILC. We also study the occupancy of the electromagnetic calorimeter. These estimates are compared with measurements, e.g. of the radiation damage of FPGAs, done elsewhere. The outcome of the study shows that the radiation doses and the annual flux is low enough to allow today's FPGAs to operate. The Single Event Upset rate, however, lies between 14 min and 12 h depending on the FPGA used and therefore needs to be considered in the design of the data acquisition system of the electromagnetic calorimeter. The occupancy is about 0.002 per bunch train not taking into account the effect of noise which depends on the choice of the detector.

  5. Evaluation of Electromagnetic Fields in a Hospital for Safe Use of Electronic Medical Equipment.

    PubMed

    Ishida, Kai; Fujioka, Tomomi; Endo, Tetsuo; Hosokawa, Ren; Fujisaki, Tetsushi; Yoshino, Ryoji; Hirose, Minoru

    2016-03-01

    Establishment of electromagnetic compatibility is important in use of electronic medical equipment in hospitals. To evaluate the electromagnetic environment, the electric field intensity induced by electromagnetic radiation in broadcasting spectra coming from outside the hospital was measured in a new hospital building before any patients visited the hospital and 6 months after the opening of the hospital. Various incoming radio waves were detected on the upper floors, with no significant difference in measured levels before and after opening of the hospital. There were no cellphone terminal signals before the hospital opened, but these signals were strongly detected at 6 months thereafter. Cellphone base stations signals were strongly detected on the upper floors, but there were no signals at most locations in the basement and in the center of the building on the lower floors. A maximum electrical intensity of 0.28 V/m from cellphone base stations (2.1 GHz) was detected at the south end of the 2nd floor before the hospital opened. This value is lower than the EMC marginal value for general electronic medical equipment specified in IEC 60601-1-2 (3 V/m). Therefore, electromagnetic interference with electronic medical equipment is unlikely in this situation. However, cellphone terminal signals were frequently detected in non-base station signal areas. This is a concern, and understanding signal strength from cellphone base stations at a hospital is important for promotion of greater safety.

  6. Electron cooling for the Fermilab recycler: Present concept and provisional parameters

    SciTech Connect

    Nagaitsev, S.

    1997-09-01

    In all scenarios of the possible Tevatron upgrades, luminosity is essentially proportional to the number of antiprotons. Thus, a tenfold increase in luminosity could be achieved by putting five times more protons on the antiproton production target and gaining an additional factor of two from recycling antiprotons left over from the previous store. Stacking and storing ten times more antiprotons puts an unbearable burden on the stochastic cooling system of the existing Accumulator Ring. Thus, one is led to consider an additional stage of antiproton storage the so called Recycler Ring. Electron cooling of the 8 GeV antiprotons in the Recycler could provide an attractive way around the problems of large stacks. Such a system would look much like the IUCF proposal to cool 12 GeV protons in the SSC Medium Energy Booster. Although electron cooling has now become a routine tool in many laboratories, its use has been restricted to lower energy accelerators (< 500 MeV/nucleon). An R&D program is currently underway at Fermilab to extend electron cooling technology to the GeV range. This paper describes the electron cooling system design as well as the Recycler ring parameters required to accommodate this system.

  7. FEL-based coherent electron cooling for high-energy hadron colliders

    SciTech Connect

    Litvinenko,V.N.; Derbenev, Y.S.

    2008-06-23

    Cooling intense high-energy hadron beams is a major challenge in modern accelerator physics. Synchrotron radiation is too feeble and two common methods--stochastic and electron cooling--are not efficient in providing significant cooling for high energy, high intensity proton colliders. In this paper they discuss a practical scheme of Coherent Electron Cooling (CeC), which promises short cooling times (below one hour) for intense proton beams in RHIC at 250 GeV or in LHC at 7 TeV. A possibility of CeC using various microwave instabilities was discussed since 1980s. In this paper, they present first evaluation of specific CeC scheme based on capabilities of present-day accelerator technology, ERLs, and high-gain Free-Electron lasers (FELs). They discuss the principles, the main limitations of this scheme and present some predictions for Coherent Electron Cooling in RHIC and the LHC operating with ions or protons, summarized in Table 1.

  8. Proof-of-Principle Experiment for FEL-based Coherent Electron Cooling

    SciTech Connect

    Litvinenko, V; Bengtsson, J; Fedotov, A V; Hao, Y; Kayran, D; Mahler, G J; Meng, W; Roser, T; Sheehy, B; Than, R; Tuozzolo, J E; Wang, G; Webb, S D; Yakimenko, V; Bell, G I; Bruhwiler, D L; Schwartz, B T; Hutton, A; Krafft, G A; Poelker, M; Rimmer, R A

    2011-03-01

    Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders*. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using one of JLab’s SRF cryo-modules. In this paper, we describe the experimental setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC.

  9. Inhibition of electron thermal conduction by electromagnetic instabilities. [in stellar coronas

    NASA Technical Reports Server (NTRS)

    Levinson, Amir; Eichler, David

    1992-01-01

    Heat flux inhibition by electromagnetic instabilities in a hot magnetized plasma is investigated. Low-frequency electromagnetic waves become unstable due to anisotropy of the electron distribution function. The chaotic magnetic field thus generated scatters the electrons with a specific effective mean free path. Saturation of the instability due to wave-wave interaction, nonlinear scattering, wave propagation, and collisional damping is considered. The effective mean free path is found self-consistently, using a simple model to estimate saturation level and scattering, and is shown to decrease with the temperature gradient length. The results, limited to the assumptions of the model, are applied to astrophysical systems. For some interstellar clouds the instability is found to be important. Collisional damping stabilizes the plasma, and the heat conduction can be dominated by superthermal electrons.

  10. Hall viscosity and electromagnetic response of electrons in graphene

    NASA Astrophysics Data System (ADS)

    Sherafati, Mohammad; Principi, Alessandro; Vignale, Giovanni

    2016-09-01

    We derive an analytic expression for the geometric Hall viscosity of noninteracting electrons in a single graphene layer in the presence of a perpendicular magnetic field. We show that a recently derived formula in C. Hoyos and D. T. Son [Phys. Rev. Lett. 108, 066805 (2012), 10.1103/PhysRevLett.108.066805], which connects the coefficient of q2 in the wave-vector expansion of the Hall conductivity σx y(q ) of the two-dimensional electron gas (2DEG) to the Hall viscosity and the orbital diamagnetic susceptibility of that system, continues to hold for graphene, in spite of the lack of Galilean invariance, with a suitable definition of the effective mass. We also show that, for a sufficiently large number of occupied Landau levels in the positive-energy sector, the Hall conductivity of electrons in graphene reduces to that of a Galilean-invariant 2DEG with an effective mass given by ℏ kF/vF (cyclotron mass). Even in the most demanding case, i.e., when the chemical potential falls between the zeroth and the first Landau levels, the cyclotron mass formula gives results accurate to better than 1%. The connection between the Hall conductivity and the viscosity provides a possible avenue to measure the Hall viscosity in graphene.

  11. Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene.

    PubMed

    Mihnev, Momchil T; Tolsma, John R; Divin, Charles J; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A; MacDonald, Allan H; Norris, Theodore B

    2015-09-24

    In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron-phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied.

  12. Modulation of a compressional electromagnetic wave in a magnetized electron-positron quantum plasma

    NASA Astrophysics Data System (ADS)

    Amin, M. R.

    2015-09-01

    Amplitude modulation of a compressional electromagnetic wave in a strongly magnetized electron-positron pair plasma is considered in the quantum magnetohydrodynamic regime. The important ingredients of this study are the inclusion of the external strong magnetic field, Fermi quantum degeneracy pressure, particle exchange potential, quantum diffraction effects via the Bohm potential, and dissipative effect due to collision of the charged carriers. A modified-nonlinear Schödinger equation is developed for the compressional magnetic field of the electromagnetic wave by employing the standard reductive perturbation technique. The linear and nonlinear dispersions of the electromagnetic wave are discussed in detail. For some parameter ranges, relevant to dense astrophysical objects such as the outer layers of white dwarfs, neutron stars, and magnetars, etc., it is found that the compressional electromagnetic wave is modulationally unstable and propagates as a dissipated electromagnetic wave. It is also found that the quantum effects due to the particle exchange potential and the Bohm potential are negligibly small in comparison to the effects of the Fermi quantum degeneracy pressure. The numerical results on the growth rate of the modulation instability is also presented.

  13. Strategy for alignment of electron beam trajectory in LEReC cooling section

    SciTech Connect

    Seletskiy, S.; Blaskiewicz, M.; Fedotov, A.; Kayran, D.; Kewisch, J.; Michnoff, R.; Pinayev, I.

    2016-09-23

    We considered the steps required to align the electron beam trajectory through the LEReC cooling section. We devised a detailed procedure for the beam-based alignment of the cooling section solenoids. We showed that it is critical to have an individual control of each CS solenoid current. Finally, we modeled the alignment procedure and showed that with two BPM fitting the solenoid shift can be measured with 40 um accuracy and the solenoid inclination can be measured with 30 urad accuracy. These accuracies are well within the tolerances of the cooling section solenoid alignment.

  14. Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene

    PubMed Central

    Mihnev, Momchil T.; Tolsma, John R.; Divin, Charles J.; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A.; MacDonald, Allan H.; Norris, Theodore B.

    2015-01-01

    In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron–phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied. PMID:26399955

  15. Super-Planckian Electron Cooling in a van der Waals Stack

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Lundeberg, Mark B.; Hesp, Niels C. H.; Tielrooij, Klaas-Jan; Koppens, Frank H. L.; Polini, Marco

    2017-03-01

    Radiative heat transfer (RHT) between macroscopic bodies at separations that are much smaller than the thermal wavelength is ruled by evanescent electromagnetic modes and can be orders of magnitude more efficient than its far-field counterpart, which is described by the Stefan-Boltzmann law. In this Letter, we present a microscopic theory of RHT in van der Waals stacks comprising graphene and a natural hyperbolic material, i.e., hexagonal boron nitride (hBN). We demonstrate that RHT between hot carriers in graphene and hyperbolic phonon polaritons in hBN is extremely efficient at room temperature, leading to picosecond time scales for the carrier cooling dynamics.

  16. Kinetic Electron Closures for Electromagnetic Simulation of Drift and Shear-Alfven Waves (II)

    SciTech Connect

    Cohen, B I; Dimits, A M; Nevins, W M; Chen, Y; Parker, S

    2001-10-11

    An electromagnetic hybrid scheme (fluid electrons and gyrokinetic ions) is elaborated in example calculations and extended to toroidal geometry. The scheme includes a kinetic electron closure valid for {beta}{sub e} > m{sub e}/m{sub i} ({beta}{sub e} is the ratio of the plasma electron pressure to the magnetic field energy density). The new scheme incorporates partially linearized ({delta}f) drift-kinetic electrons whose pressure and number density moments are used to close the fluid momentum equation for the electron fluid (Ohm's law). The test cases used are small-amplitude kinetic shear-Alfven waves with electron Landau damping, the ion-temperature-gradient instability, and the collisionless drift instability (universal mode) in an unsheared slab as a function of the plasma {beta}{sub e}. Attention is given to resolution and convergence issues in simulations of turbulent steady states.

  17. Evidence of local power deposition and electron heating by a standing electromagnetic wave in electron-cyclotron-resonance plasma.

    PubMed

    Durocher-Jean, A; Stafford, L; Dap, S; Makasheva, K; Clergereaux, R

    2014-09-01

    Microwave plasmas excited at electron-cyclotron resonance were studied in the 0.5-15 mTorr pressure range. In contrast with low-limit pressure conditions where the plasma emission highlights a fairly homogeneous spatial structure, a periodic spatial modulation (period ∼6.2 cm) appeared as pressure increased. This feature is ascribed to a local power deposition (related to the electron density) due to the presence of a standing electromagnetic wave created by the feed electromagnetic field (2.45 GHz) in the cavity formed by the reactor walls. Analysis of the electron energy probability function by Langmuir probe and optical emission spectroscopy further revealed the presence of a high-energy tail that showed strong periodic spatial modulation at higher pressure. The spatial evolution of the electron density and of the characteristic temperature of these high-energy electrons coincides with the nodes (maximum) and antinodes (minimum) of the standing wave. These spatially-modulated power deposition and electron heating mechanisms are then discussed.

  18. Enhancement in Cooling of Electronic Components by Nanofluids

    NASA Astrophysics Data System (ADS)

    Khatak, Pankaj; Jakhar, Rahul; Kumar, Mahesh

    2015-04-01

    In this study, heat transfer during spray cooling was studied experimentally using water and ZnO nanofluid. Various experiments were performed using a spray nozzle impinging fluid normal to the flat end of a copper heated surface (copper cylinder 20 mm diameter). The heat flux and surface temperature have been calculated by measuring temperature gradients along the target length under steady state conditions. In this experimental study, water flow rate was varied from 15 to 25 ml/min. In the same test conditions to compare water results with nanofluids, ZnO nanofluid was sprayed at a flow rate of 20 ml/min. It can be observed that a surface temperature 74.1 °C was obtained with maximum heat flux of 102.40 W/cm2 under the test condition for heater power 140 W and a water flow rate 25 ml/min. The use of ZnO nanofluid as a coolant is observed to increase the heat flux by about 20.2 % and decrease surface temperature of the test specimen by about 15 % at 180 W heat input and flow rate of 20 ml/min. The uncertainty in heat flux is observed to vary from 8.63 to 10.93 %.

  19. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current

    NASA Astrophysics Data System (ADS)

    Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C.

    2016-03-01

    Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

  20. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current.

    PubMed

    Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2016-03-21

    Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

  1. Cooling of nanomechanical resonators by thermally activated single-electron transport.

    PubMed

    Santandrea, F; Gorelik, L Y; Shekhter, R I; Jonson, M

    2011-05-06

    We show that the vibrations of a nanomechanical resonator can be cooled to near its quantum ground state by tunneling injection of electrons from a scanning tunneling microscope tip. The interplay between two mechanisms for coupling the electronic and mechanical degrees of freedom results in a bias-voltage-dependent difference between the probability amplitudes for vibron emission and absorption during tunneling. For a bias voltage just below the Coulomb blockade threshold, we find that absorption dominates, which leads to cooling corresponding to an average vibron population of the fundamental bending mode of 0.2.

  2. On the continuous spectrum electromagnetic radiation in electron-fullerene collision

    SciTech Connect

    Amusia, M.Y.

    1995-08-01

    It is demonstrated that the electromagnetic radiation spectrum in electron-fullerene collisions is dominated by a huge maximum of multielectron nature, similar to that already predicted and observed in photoabsorption. Due to coherence, the intensity of this radiation is much stronger than the sum of the intensities of isolated atoms. Experimental detection of such radiation would be of great importance for understanding the mechanism of its formation and for investigating fullerene structures. A paper describing these results was published.

  3. Experimental study of high-temperature superconductor shield for electron cooling system

    NASA Astrophysics Data System (ADS)

    Smirnov, A.; Dorofeev, G.; Drobin, V.; Kulikov, E.; Malinovski, H.

    2016-12-01

    The NICA project includes a system of electron cooling for charged particle beams for total ion energy of 4.5 GeV/n. To achieve the required cooling time, the magnetic field homogeneity in the cooling section should be at least 10-5 for a solenoid length in the cooling system of about 6 m. The cost of such solenoid, however, is very high due to the complexity of high-precision winding. The application of the superconducting shield could help to resolve this problem. In this study we present the results of an experimental investigation of the prototype of the shield manufactured from high-temperature superconductor (HTS) tapes. The measurements were performed at different quasistationary operating conditions. The requirements for the HTS shield and solenoid parameters are formulated.

  4. The integration of liquid cryogen cooling and cryocoolers with superconducting electronic systems

    NASA Astrophysics Data System (ADS)

    Green, Michael A.

    2003-12-01

    The need for cryogenic cooling has been a critical issue that has kept superconducting electronic devices from reaching the market place. Even though the performance of many of the superconducting circuits is superior to silicon electronics, the requirement for cryogenic cooling has put the superconducting devices at a serious disadvantage. This paper discusses the process of refrigerating superconducting devices with cryogenic liquids and small cryocoolers. Three types of cryocoolers are compared for vibration, efficiency and reliability. The connection of a cryocooler to the load is discussed. A comparison of using flexible copper straps to carry the heat load and using heat pipe is shown. The type of instrumentation needed for monitoring and controlling the cooling is discussed.

  5. NREL Helps Cool the Power Electronics in Electric Vehicles (Fact Sheet)

    SciTech Connect

    Not Available

    2011-07-01

    Researchers at the National Renewable Energy Laboratory (NREL) are developing and demonstrating innovative heat-transfer technologies for cooling power electronics devices in hybrid and electric vehicles. In collaboration with 3M and Wolverine Tube, Inc., NREL is using surface enhancements to dissipate heat more effectively, permitting a reduction in the size of power electronic systems and potentially reducing the overall costs of electric vehicles.

  6. Electronics cooling of Phenix multiplicity and vertex detector

    SciTech Connect

    Chen, Z.; Gregory, W.S.

    1996-08-01

    The Multiplicity and Vertex Detector (MVD) uses silicon strip sensors arranged in two concentric barrels around the beam pipe of the PHENIX detector that will be installed at Brookhaven National Laboratory. Each silicon sensor is connected by a flexible kapton cable to its own front-end electronics printed circuit board that is a multi-chip module or MCM. The MCMs are the main heat source in the system. To maintain the MVD at optimized operational status, the maximum temperature of the multi-chip modules must be below 40 C. Using COSMOS/M HSTAR for the Heat Transfer analysis, a finite element model of a typical MCM plate was created to simulate a 9m/s airflow and 9m/s mixed flow composed of 50% helium and 50% air respectively, with convective heat transfer on both sides of the plate. The results using a mixed flow of helium and air show that the average maximum temperature reached by the MCMs is 37.5 C. The maximum temperature which is represented by the hot spots on the MCM is 39.43 C for the helium and air mixture which meets the design temperature requirement 40 C. To maintain the Multiplicity and Vertex Detector at optimized operational status, the configuration of the plenum chamber, the power dissipated by the silicon chips, the fluid flow velocity and comparison on the MCM design parameters will be discussed.

  7. Hybridized electromagnetic-triboelectric nanogenerator for scavenging biomechanical energy for sustainably powering wearable electronics.

    PubMed

    Zhang, Kewei; Wang, Xue; Yang, Ya; Wang, Zhong Lin

    2015-01-01

    We report a hybridized electromagnetic-triboelectric nanogenerator for highly efficient scavenging of biomechanical energy to sustainably power wearable electronics by human walking. Based on the effective conjunction of triboelectrification and electromagnetic induction, the hybridized nanogenerator, with dimensions of 5 cm × 5 cm × 2.5 cm and a light weight of 60 g, integrates a triboelectric nanogenerator (TENG) that can deliver a peak output power of 4.9 mW under a loading resistance of 6 MΩ and an electromagnetic generator (EMG) that can deliver a peak output power of 3.5 mW under a loading resistance of 2 kΩ. The hybridized nanogenerator exhibits a good stability for the output performance and a much better charging performance than that of an individual energy-harvesting unit (TENG or EMG). Furthermore, the hybridized nanogenerator integrated in a commercial shoe has been utilized to harvest biomechanical energy induced by human walking to directly light up tens of light-emitting diodes in the shoe and sustainably power a smart pedometer for reading the data of a walking step, distance, and energy consumption. A wireless pedometer driven by the hybrid nanogenerator can work well to send the walking data to an iPhone under the distance of 25 m. This work pushes forward a significant step toward energy harvesting from human walking and its potential applications in sustainably powering wearable electronics.

  8. Excitation threshold of Stimulated Electromagnetic Emissions SEEs generated at pump frequency near the third electron gyroharmonic

    NASA Astrophysics Data System (ADS)

    Mahmoudian, A.; Bernhardt, P. A.; Scales, W.

    2012-12-01

    The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaska provides effective radiated powers in the megawatt range that have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. In recent HAARP heating experiments, it has been shown that during the Magnetized Stimulated Brillouin Scattering MSBS instability, the pumped electromagnetic wave may decay into an electromagnetic wave and a low frequency electrostatic wave (either ion acoustic IA wave or electrostatic ion cyclotron EIC wave). Using Stimulated Electromagnetic Emission (SEE) spectral features, side bands which extend above and below the pump frequency can yield significant diagnostics for the modified ionosphere. It has been shown that the IA wave frequency offsets can be used to measure electron temperature in the heated ionosphere and EIC wave offsets can be used as a sensitive method to determine the ion species by measuring ion mass using the ion gyro-frequency offset. The threshold of each emission line has been measured by changing the amplitude of pump wave. The experimental results aimed to show the threshold for transmitter power to excite IA wave propagating along the magnetic field lines as well as for EIC wave excited at an oblique angle relative to the background magnetic field. Another parametric decay instability studied is the ion Bernstein decay instability that has been attributed to the simultaneous parametric decay of electron Bernstein waves into multiple electron Bernstein and ion Bernstein waves. The SIB process is thought to involve mode conversion from EM to EB waves followed by parametric decay of the EB wave to multiple EB and IB waves. The parametric decay instability of ion Bernstein modes has been observed simultaneously for the first time at the third electron gyroharmonics during 2011 Summer Student Research

  9. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    NASA Astrophysics Data System (ADS)

    Lobato, I.; Rojas, J.; Landauro, C. V.; Torres, J.

    2009-02-01

    The structural evolution and dynamics of silver nanodrops Ag2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 × 1013 K s-1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 × 1012 K s-1), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  10. Control of spin dynamics in a two-dimensional electron gas by electromagnetic dressing

    NASA Astrophysics Data System (ADS)

    Pervishko, A. A.; Kibis, O. V.; Morina, S.; Shelykh, I. A.

    2015-11-01

    We solved the Schrödinger problem for a two-dimensional electron gas (2DEG) with the Rashba spin-orbit interaction in the presence of a strong high-frequency electromagnetic field (dressing field). The found eigenfunctions and eigenenergies of the problem are used to describe the spin dynamics of the dressed 2DEG within the formalism of the density matrix response function. Solving the equations of spin dynamics, we show that the dressing field can switch the spin relaxation in the 2DEG between the cases corresponding to the known Elliott-Yafet and D'yakonov-Perel' regimes. As a result, the spin properties of the 2DEG can be tuned by a high-frequency electromagnetic field. The present effect opens an unexplored way for controlling the spin with light and, therefore, forms the physical prerequisites for creating light-tuned spintronics devices.

  11. Two-dimensional electromagnetic Child-Langmuir law of a short-pulse electron flow

    SciTech Connect

    Chen, S. H.; Tai, L. C.; Liu, Y. L.; Ang, L. K.; Koh, W. S.

    2011-02-15

    Two-dimensional electromagnetic particle-in-cell simulations were performed to study the effect of the displacement current and the self-magnetic field on the space charge limited current density or the Child-Langmuir law of a short-pulse electron flow with a propagation distance of {zeta} and an emitting width of W from the classical regime to the relativistic regime. Numerical scaling of the two-dimensional electromagnetic Child-Langmuir law was constructed and it scales with ({zeta}/W) and ({zeta}/W){sup 2} at the classical and relativistic regimes, respectively. Our findings reveal that the displacement current can considerably enhance the space charge limited current density as compared to the well-known two-dimensional electrostatic Child-Langmuir law even at the classical regime.

  12. Simulations of electromagnetic emissions produced in a thin plasma by a continuously injected electron beam

    NASA Astrophysics Data System (ADS)

    Annenkov, V. V.; Timofeev, I. V.; Volchok, E. P.

    2016-05-01

    In this paper, electromagnetic emissions produced in a thin beam-plasma system are studied using two-dimensional particle-in-cell simulations. For the first time, the problem of emission generation in such a system is considered in a realistic formulation allowing for the continuous injection of a relativistic electron beam through a plasma boundary. Specific attention is given to the thin plasma case in which the transverse plasma size is comparable to the typical wavelength of beam-driven oscillations. Such a case is often implemented in laboratory beam-plasma experiments and has a number of peculiarities. Emission from a thin plasma does not require intermediate generation of the electromagnetic plasma eigenmodes, as in an infinite case, and is more similar to the regular antenna radiation. In this work, we determine how efficiently the fundamental and the second harmonic emissions can be generated in previously modulated and initially homogeneous plasmas.

  13. Attachment cooling of electrons in oxygen-argon and SF6-argon mixtures

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia; Kim, Sung Jin; Park, Gan Young; Lee, Jae Koo

    2004-09-01

    In e-beam sustained plasma different electron temperature can be obtained. Thus, in plasma of capacitive RF discharges in inert gases typical electron temperature is of the order of 2-3 eV. At certain conditions, in plasma of electronegative gases electron temperature can approach ion/neutral temperature. We consider e-beam sustained plasma of electronegative gases and their mixtures with argon where the main mechanism of plasma neutralization is connected with electron-molecule attachment. In such plasma, due to retardation of fast electrons of e-beam secondary electrons are created which loose their energy due to attachment. It is shown, that at certain conditions (in dependence of the e-beam intensity and spectrum of secondary electrons) electron temperature can obtain the values comparable or even less than temperature of neutral component. The effect can be explained by the increase of attachment rate coefficient with the increase of electron temperature (mean electron energy). Such a dependence leads to attachment of the fastest plasma electrons and selective loss of electrons whose energy exceeds the mean electron energy and, as a result, to effective electron cooling. The theoretical and numerical analysis of the problem has been conducted. The numerical results obtained using ELENDIF code are compared with Particle-in-cell/Monte Carlo simulations under similar conditions.

  14. A practical procedure to prevent electromagnetic interference with electronic medical equipment.

    PubMed

    Hanada, Eisuke; Takano, Kyoko; Antoku, Yasuaki; Matsumura, Kouji; Watanabe, Yoshiaki; Nose, Yoshiaki

    2002-02-01

    Problems involving electromagnetic interference (EMI) with electronic medical equipment are well-documented. However, no systematic investigation of EMI has been done. We have systematically investigated the causes of EMI. The factors involved in EMI were determined as follows: 1) Electric-field intensity induced by invasive radio waves from outside a hospital. 2) Residual magnetic-flux density at welding points in a building. 3) Electric-field intensity induced by conveyance systems with a linear motor. 4) The shielding capacity of hospital walls. 5) The shielding capacity of commercial shields against a wide range frequency radio waves. 6) The immunity of electronic medical equipment. 7) EMI by cellular telephone and personal handy-phone system handsets. From the results of our investigation, we developed a following practical procedure to prevent EMI. 1) Measurement of electric-field intensity induced by invasive radio waves from outside the hospital and industrial systems in the hospital. 2) Measurement of residual magnetic-flux density at electric welding points of hospital buildings with steel frame structures. 3) Control of the electromagnetic environment by utilizing the shielding capacity of walls. 4) Measurement of the immunity of electronic medical equipment. And 5) Installation of electronic gate equipment at the building entrance to screen for handsets.

  15. Possible electromagnetic interference with electronic medical equipment by radio waves coming from outside the hospital.

    PubMed

    Hanada, E; Kodama, K; Takano, K; Watanabe, Y; Nose, Y

    2001-08-01

    Electromagnetic interference (EMI) with electronic medical equipment by radio waves from mobile telephone handsets has been reported and is currently receiving wide attention. The possibility of EMI with electronic medical equipment by radio waves coming into the hospital has also been pointed out. But so far, there are no reports measuring the frequency distribution of electric field intensity induced by incoming radio waves. Therefore, we measured electric field intensity induced by radio waves coming into our 11-floor hospital, which was under construction. The maximum intensity observed was about 200 V/m at 2.79 GHz, from airport surveillance radar waves. The maximum intensity induced by radio waves from cellular phone base stations was 1.78 V/m. These data show that various frequencies of radio waves are common in this urban area, and that they induce strong electricfield intensity. This strong electric field intensity might cause EMI with electronic medical equipment. Measurement of the electromagnetic environment should be done by each hospital in urban areas to prevent EMI with electronic medical equipment.

  16. Cyclotron resonance cooling by strong laser field

    SciTech Connect

    Tagcuhi, Toshihiro; Mima, Kunioka

    1995-12-31

    Reduction of energy spread of electron beam is very important to increase a total output radiation power in free electron lasers. Although several cooling systems of particle beams such as a stochastic cooling are successfully operated in the accelerator physics, these cooling mechanisms are very slow and they are only applicable to high energy charged particle beams of ring accelerators. We propose here a new concept of laser cooling system by means of cyclotron resonance. Electrons being in cyclotron motion under a strong magnetic field can resonate with circular polarized electromagnetic field, and the resonance take place selectively depending on the velocity of the electrons. If cyclotron frequency of electrons is equal to the frequency of the electromagnetic field, they absorb the electromagnetic field energy strongly, but the other electrons remain unchanged. The absorbed energy will be converted to transverse kinetic energy, and the energy will be dumped into the radiation energy through bremastrahlung. To build a cooling system, we must use two laser beams, where one of them is counter-propagating and the other is co-propagating with electron beam. When the frequency of the counter-propagating laser is tuned with the cyclotron frequency of fast electrons and the co-propagating laser is tuned with the cyclotron frequency of slow electrons, the energy of two groups will approach and the cooling will be achieved. We solve relativistic motions of electrons with relativistic radiation dumping force, and estimate the cooling rate of this mechanism. We will report optimum parameters for the electron beam cooling system for free electron lasers.

  17. Laser cooling of electron – ion plasma in the case of optimal scanning of the laser frequency

    SciTech Connect

    Gavrilyuk, A P; Isaev, I L

    2015-11-30

    Laser cooling of ions of electron – ion plasma is studied under the action of spontaneous radiation pressure forces. It is shown that the use of a constant detuning of the laser frequency from the quantum transition frequency w0 in ions significantly limits the conditions under which the ions are cooled. To extend the range of initial temperatures of possible cooling of ions and to increase the cooling efficiency we suggest scanning the laser frequency detuning so that the cooling rate remained maximal in the process of changing the temperature of ions. In the case of an optimal detuning, we have found an asymptotic expression for the cooling rate and identified intervals of electron concentrations and temperatures, where cooling of ions is possible. (interaction of laser radiation with matter. laser plasma)

  18. Resonant two-photon annihilation of an electron-positron pair in a pulsed electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Voroshilo, A. I.; Roshchupkin, S. P.; Nedoreshta, V. N.

    2016-09-01

    Two-photon annihilation of an electron-positron pair in the field of a plane low-intensity circularly polarized pulsed electromagnetic wave was studied. The conditions for resonance of the process which are related to an intermediate particle that falls within the mass shell are studied. In the resonant approximation the probability of the process was obtained. It is demonstrated that the resonant probability of two-photon annihilation of an electron-positron pair may be several orders of magnitude higher than the probability of this process in the absence of the external field. The obtained results may be experimentally verified by the laser facilities of the international megaprojects, for example, SLAC (National Accelerator Laboratory), FAIR (Facility for Antiproton and Ion Research), and XFEL (European X-Ray Free-Electron Laser).

  19. Nonlinear electromagnetic perturbations in a degenerate ultrarelativistic electron-positron plasma.

    PubMed

    El-Taibany, W F; Mamun, A A

    2012-02-01

    Nonlinear propagation of fast and slow magnetosonic perturbation modes in an ultrarelativistic, ultracold, degenerate (extremely dense) electron positron (EP) plasma (containing ultrarelativistic, ultracold, degenerate electron and positron fluids) has been investigated by the reductive perturbation method. The Alfvén wave velocity is modified due to the presence of the enthalpy correction in the fluid equations of motion. The degenerate EP plasma system (under consideration) supports the Korteweg-de Vries (KdV) solitons, which are associated with either fast or slow magnetosonic perturbation modes. It is found that the ultrarelativistic model leads to compressive (rarefactive) electromagnetic solitons corresponding to the fast (slow) wave mode. There are certain critical angles, θ(c), at which no soliton solution is found corresponding to the fast wave mode. For the slow mode, the magnetic-field intensity affects both the soliton amplitude and width. It is also illustrated that the basic features of the electromagnetic solitary structures, which are found to exist in such a degenerate EP plasma, are significantly modified by the effects of enthalpy correction, electron and positron degeneracy, magnetic-field strength, and the relativistic effect. The applications of the results in a pair-plasma medium, which occurs in many astrophysical objects (e.g., pulsars, white dwarfs, and neutron stars) are briefly discussed.

  20. A passive opto-electronic lightning sensor based on electromagnetic field detection for utilities applications

    NASA Astrophysics Data System (ADS)

    Rosolem, J. B.; Barbosa, C. F.; Floridia, C.; Bezerra, E. W.

    2010-09-01

    This paper presents the results of a passive optical lightning sensor for utilities applications. The main sensor application is for the location of lightning strikes in overhead power lines, but it can also be used in substations or in power generation plants. The proposed sensor detects lightning indirectly by means of detecting lightning electromagnetic pulses, which are used to modulate directly a semiconductor laser coupled to a fibre optic pigtail. No solar panels, batteries or electronic control circuits are necessary to implement this sensing technique. This paper shows the results of the sensor characterization made only in laboratory and the possibilities of its use in an optical WDM sensor network.

  1. Electromagnetic properties of massive neutrinos in low-energy elastic neutrino-electron scattering

    NASA Astrophysics Data System (ADS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2017-03-01

    A thorough account of electromagnetic interactions of massive neutrinos in the theoretical formulation of low-energy elastic neutrino-electron scattering is given. The formalism of neutrino charge, magnetic, electric, and anapole form factors defined as matrices in the mass basis is employed under the assumption of three-neutrino mixing. The flavor change of neutrinos traveling from the source to the detector is taken into account and the role of the source-detector distance is inspected. The effects of neutrino flavor-transition millicharges and charge radii in the scattering experiments are pointed out.

  2. Proof-of-principle experiment for FEL-based coherent electron cooling

    SciTech Connect

    Litvinenko, V.N.; Belomestnykh, S.; Ben-Zvi, I.; Brutus, J.C.; Fedotov, A.; Hao, Y.; Kayran, D.; Mahler, G.; Marusic, A.; Meng, W.; McIntyre, G.; Minty, M.; Ptitsyn, V.; Pinayev, I.; Rao, T.; Roser, T.; Sheehy, B.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tuozzolo, J.; Wang, G.; Yakimenko, V.; Poelker, M.; Hutton, A.; Kraft, G.; Rimmer, R.; Bruhwiler, D.L.; Abell, D.T.; Nieter, C.; Ranjbar, V.; Schwartz, B.T.; Vobly, P.; Kholopov, M.; Shevchenko, O.; Mcintosh, P.; Wheelhouse, A.

    2011-08-21

    Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron-hadron and electron-hadron colliders. In a CEC system, a hadron beam interacts with a cooling electron beam. A perturbation of the electron density caused by ions is amplified and fed back to the ions to reduce the energy spread and the emittance of the ion beam. To demonstrate the feasibility of CEC we propose a proof-of-principle experiment at RHIC using SRF linac. In this paper, we describe the setup for CeC installed into one of RHIC's interaction regions. We present results of analytical estimates and results of initial simulations of cooling a gold-ion beam at 40 GeV/u energy via CeC. We plan to complete the program in five years. During first two years we will build coherent electron cooler in IP2 of RHIC. In parallel we will develop complete package of computer simulation tools for the start-to-end simulation predicting exact performance of a CeC. The later activity will be the core of Tech X involvement into the project. We will use these tools to predict the performance of our CeC device. The experimental demonstration of the CeC will be undertaken in years three to five of the project. The goal of this experiment is to demonstrate the cooling of ion beam and to compare its measured performance with predictions made by us prior to the experiments.

  3. Terahertz electromagnetic wave generation and amplification by an electron beam in the elliptical plasma waveguides with dielectric rod

    SciTech Connect

    Rahmani, Z. Jazi, B.; Heidari-Semiromi, E.

    2014-09-15

    The propagation of electromagnetic waves in an elliptical plasma waveguide including strongly magnetized plasma column and a dielectric rod is investigated. The dispersion relation of guided hybrid electromagnetic waves is obtained. Excitation of the waves by a thin annular relativistic elliptical electron beam will be studied. The time growth rate of electromagnetic waves is obtained. The effects of relative permittivity constant of dielectric rod, radius of dielectric rod, accelerating voltage, and current density of the annular elliptical beam on the growth rate and the frequency spectra are numerically presented.

  4. The spectral-angular and polarization characteristics of radiation from an electron beam traversing an inhomogeneous electromagnetic wave

    SciTech Connect

    Koltsov, A.V.; Serov, A.V.

    1995-12-31

    The generation of frequency harmonics of a radiation when the electron beam traverse the inhomogeneous electromagnetic wave was investigated. The electromagnetic wave are linearly polarized. The plane beam of particles enters the wave at right angle with respect to the direction of propogation of the wave and the vector E of the wave. The spartial distribution of radiation from the higher harmonics and the power density contours are caculated.

  5. Towards the measurement of the electron EDM with laser cooled francium atoms

    NASA Astrophysics Data System (ADS)

    Kawamura, Hirokazu; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Sakamoto, K.; Uchiyama, A.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Nataraj, H. S.; Sato, T.; Shimizu, Y.; Yoshida, H. P.; Wakasa, T.; Sakemi, Y.

    2014-09-01

    The electric dipole moment (EDM) of a particle is a probe into new physics beyond the standard model. The electron EDM might be observed with an enhancement in heavier paramagnetic atoms. Francium (Fr), whose electron structure is useful for laser-cooling and trapping, has a large enhancement factor. Fr produced at high temperature via a fusion reaction will be laser-cooled and trapped in an optical lattice where the EDM is measured. The magneto-optical trapping of Fr is required in advance of the lattice trapping. The technique observing a small number of atoms makes it easy to search for the resonant frequency of Fr. The improvement of the beam purity should lead to a more efficient trap. The techniques towards Fr trapping and EDM measurement have been developed. The electric dipole moment (EDM) of a particle is a probe into new physics beyond the standard model. The electron EDM might be observed with an enhancement in heavier paramagnetic atoms. Francium (Fr), whose electron structure is useful for laser-cooling and trapping, has a large enhancement factor. Fr produced at high temperature via a fusion reaction will be laser-cooled and trapped in an optical lattice where the EDM is measured. The magneto-optical trapping of Fr is required in advance of the lattice trapping. The technique observing a small number of atoms makes it easy to search for the resonant frequency of Fr. The improvement of the beam purity should lead to a more efficient trap. The techniques towards Fr trapping and EDM measurement have been developed. Supported by MEXT/JSPS KAKENHI Grants (21104005, 25610112 and 26220705) and Tohoku University's Focused Research Project.

  6. Status of Proof-of-principle Experiment for Coherent Electron Cooling

    SciTech Connect

    Pinayev, I; Ben-Zvi, I; Bengtsson, J; Elizarov, A; Fedotov, A V; Gassner, D M; Hao, Y; Kayran, D; Litvinenko, V; Mahler, G J; Meng, W; Roser, T; Sheehy, B; Than, R; Tuozzolo, J E; Wang, G; Webb, S D; Yakimenko, V; Bell, G I; Bruhwiler, D L; Ranjbar, V H; Schwartz, B T; Hutton, A; Krafft, G A; Poelker, M; Rimmer, R A; Kholopov, M A; Vobly, P

    2012-07-01

    Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o'clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.

  7. The design of an asymmetric bionic branching channel for electronic chips cooling

    NASA Astrophysics Data System (ADS)

    Xu, Shanglong; Qin, Jie; Guo, Wei; Fang, Kuang

    2013-06-01

    Inspired by the wing vein of Lepidoptera, a designment of asymmetric bionic branching channel for electronic chips cooling is developed. Lepidoptera vein D was chosen to measure the angle of first and second branch level. Based on these regular patterns, an asymmetric bionic branching channel is designed in a 35 mm × 35 mm chip. Comparing with fractal-like branching channel, it provides a stronger heat transfer capability, lower pressure drop and lower flow resistance in the experiment.

  8. Status of construction of the electron cooling system for the NICA booster

    NASA Astrophysics Data System (ADS)

    Bryzgunov, M. I.; Bubley, A. V.; Goncharov, A. D.; Panasyuk, V. M.; Parkhomchuk, V. V.; Reva, V. B.

    2016-12-01

    According to the agreement, the electron cooling system for the NICA booster should be commissioned in late 2015. The degree of completion of various units and components of the installation as of September 2015 is characterized in the present report. Part of the report is devoted to discussing the performance parameters of the installation and the engineering solutions that had to be implemented to achieve such parameters.

  9. Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2013-06-01

    The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

  10. High-coherence electron and ion bunches from laser-cooled atoms.

    PubMed

    Sparkes, Ben M; Thompson, Daniel J; McCulloch, Andrew J; Murphy, Dene; Speirs, Rory W; Torrance, Joshua S J; Scholten, Robert E

    2014-08-01

    Cold atom electron and ion sources produce electron bunches and ion beams by photoionization of laser-cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultra-fast electron-diffractive imaging of dynamic processes at the nanoscale. The effective brightness of electron sources has been limited by nonlinear divergence caused by repulsive interactions between the electrons, known as the Coulomb explosion. It has been shown that electron bunches with ellipsoidal shape and uniform density distribution have linear internal Coulomb fields, such that the Coulomb explosion can be reversed using conventional optics. Our source can create bunches shaped in three dimensions and hence in principle achieve the transverse spatial coherence and brightness needed for picosecond-diffractive imaging with nanometer resolution. Here we present results showing how the shaping capability can be used to measure the spatial coherence properties of the cold electron source. We also investigate space-charge effects with ions and generate electron bunches with durations of a few hundred picoseconds. Future development of the cold atom electron and ion source will increase the bunch charge and charge density, demonstrate reversal of Coulomb explosion, and ultimately, ultra-fast coherent electron-diffractive imaging.

  11. Cool and Quiet: Partnering to Enhance the Aerodynamic and Acoustic Performance of Installed Electronics Cooling Fans: A White Paper

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle; VanZante, Dale E.

    2006-01-01

    Breathtaking images of distant planets. Spacewalks to repair a telescope in orbit. Footprints on the moon. The awesome is made possible by the mundane. Every achievement in space exploration has relied on solid, methodical advances in engineering. Space exploration fuels economic development like no other endeavor can. But which advances will make their way into our homes and businesses? And how long will it take? Answers to these questions are dependent upon industrial involvement in government sponsored research initiatives, market demands, and timing. Recognizing an opportunity is half the battle. This proposal describes the framework for a collaborative research program aimed at improving the aerodynamic and acoustic performance of electronics cooling fans. At its best, the program would involve NASA and academic researchers, as well as corporate researchers representing the Information Technology (IT) and fan manufacturing industries. The momentum of space exploration, the expertise resultant from the nation's substantial investment in turbofan noise reduction research, and the competitiveness of the IT industry are intended to be catalysts of innovation.

  12. Cooling of Electronically-Excited He2 Molecules in a Microcavity Plasma Jet

    NASA Astrophysics Data System (ADS)

    Su, Rui; Houlahan, Thomas J., Jr.; Eden, J. Gary

    2016-06-01

    Helium dimers in the d3Σ+u excited electronic state with potential energy >24 eV and radiative lifetime of 25 ns have been generated in a microcavity plasma jet and rotationally cooled by supersonic expansion in vacuum. The dynamic process of cooling is recorded by imaging the axis of expansion onto the slit of Czerny-Turner spectrometer, yielding spatial-temporal spectrograms of d3Σ+u→b3Πg (v', v'')=(0, 0) emission. Analysis of the data shows the spatial-temporal evolution of the rotational temperature to be a damped sinusoid that reaches a minimum value of 100K. This reproducible behavior is attributed to the reflection of electrons from a virtual cathode located downstream of the nozzle and indicates that the spatially-averaged electron density is 108 cm-3. We present this observed rotational temperature oscillation during the supersonic cooling process as an example of the potential of our supersonic microplasma expansion as a tool to explore physical dynamics in diatomic molecules having high excitation energies and small lifetimes.

  13. Low Energy Electron Cooling and Accelerator Physics for the Heidelberg CSR

    SciTech Connect

    Fadil, H.; Grieser, M.; Hahn, R. von; Orlov, D.; Schwalm, D.; Wolf, A.; Zajfman, D.

    2006-03-20

    The Cryogenic Storage Ring (CSR) is currently under construction at MPI-K in Heidelberg. The CSR is an electrostatic ring with a total circumference of about 34 m, straight section length of 2.5 m and will store ions in the 20 {approx} 300 keV energy range (E/Q). The cryogenic system in the CSR is expected to cool the inner vacuum chamber down to 2 K. The CSR will be equipped with an electron cooler which has also to serve as an electron target for high resolution recombination experiments. In this paper we present the results of numerical investigations of the CSR lattice with finite element calculations of the deflection and focusing elements of the ring. We also present a layout of the CSR electron cooler which will have to operate in low energy mode to cool 20 keV protons in the CSR, as well as numerical estimations of the cooling times to be expected with this device.

  14. New electronics of the spectrometric channel for the SND detector electromagnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Achasov, M. N.; Aulchenko, V. M.; Bogdanchikov, A. G.; Druzhinin, V. P.; Golubev, V. B.; Korol, A. A.; Koshuba, S. V.; Kovrizhin, D. P.; Serednyakov, S. I.; Surin, I. K.; Tekut`ev, A. I.; Usov, Yu. V.

    2016-07-01

    The Spherical Neutral Detector (SND) is intended for study of electron-positron annihilation at the VEPP-2000 e+e- collider (BINP, Novosibirsk) in the center-of-mass energy region below 2 GeV. The main part of the detector is a three-layer electromagnetic calorimeter based on NaI(Tl) crystals. The physics program of the SND experiment includes a high statistics study of neutron-antineutron production near threshold, for which time measurements in the calorimeter are required. In this paper we describe new shaping and digitizing calorimeter electronics, which allow to reach a time resolution of about 1 ns for 100 MeV signal and an amplitude resolution of about 250 keV.

  15. Propagation of terahertz electromagnetic waves in a magnetized plasma with inhomogeneous electron density and collision frequency

    NASA Astrophysics Data System (ADS)

    Guo, LinJing; Guo, LiXin; Li, JiangTing

    2017-02-01

    This study theoretically analyzes the propagation properties of terahertz (THz) electromagnetic waves in a magnetized plasma that is inhomogeneous in both collision frequency and electron density. Three parabolic profiles are adopted to describe the inhomogeneity of these two parameters in the plasma slab. Numerical calculation results show that when a magnetic field is applied, an absorption valley appears near the middle of the absorption peak. The characteristics of the absorption spectra are affected by two factors: (1) the parameters in the plasma's first layer, which is the border between the air and the plasma and (2) the gradient of the parameters across the entire plasma. Specifically, a more substantial difference between the inhomogeneous plasma and the uniform plasma corresponds to a greater difference between the two absorption spectra. In addition, electron density, plasma thickness, and collision frequency also play important roles in the propagation.

  16. Fokker-Planck electron diffusion caused by an obliquely propagating electromagnetic wave packet of narrow bandwidth

    NASA Technical Reports Server (NTRS)

    Hizanidis, Kyriakos

    1989-01-01

    The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.

  17. Scattering of strong electromagnetic wave by relativistic electrons: Thomson and Compton regimes

    NASA Astrophysics Data System (ADS)

    Potylitsyn, A. P.; Kolchuzhkin, A. M.

    2017-04-01

    The processes of the nonlinear Compton and the nonlinear Thomson scattering in a field of intense plane electromagnetic wave in terms of photon yield have been considered. The quantum consideration of the Compton scattering process allows us to calculate the probability of a few successive collisions k of an electron with laser photons accompanied by the absorption of n photons (nonlinear regime) when the number of collisions and the number of absorbed photons are of random quantities. The photon spectrum of the nonlinear Thomson scattering process was obtained from the classical formula for intensity using the Planck's law. The conditions for which the difference between the classical and the quantum regimes is manifested was obtained. Such a condition is determined by a discrete quantum radiation mechanism, namely, by the mean number of photons k bar emitted by an electron passing through the laser pulse.

  18. High-Temperature Air-Cooled Power Electronics Thermal Design: Annual Progress Report

    SciTech Connect

    Waye, Scot

    2016-08-01

    Power electronics that use high-temperature devices pose a challenge for thermal management. With the devices running at higher temperatures and having a smaller footprint, the heat fluxes increase from previous power electronic designs. This project overview presents an approach to examine and design thermal management strategies through cooling technologies to keep devices within temperature limits, dissipate the heat generated by the devices and protect electrical interconnects and other components for inverter, converter, and charger applications. This analysis, validation, and demonstration intends to take a multi-scale approach over the device, module, and system levels to reduce size, weight, and cost.

  19. Extremely field-aligned cool electrons in the dayside outer magnetosphere

    NASA Astrophysics Data System (ADS)

    Mozer, F. S.; Agapitov, O. A.; Angelopoulos, V.; Hull, A.; Larson, D.; Lejosne, S.; McFadden, J. P.

    2017-01-01

    For 200 days in 2016 while Time History of Events and Macroscale Interactions during Substorms D (THEMIS-D) was in the dayside, equatorial magnetosphere, its electron energy coverage was modified such that the first 15 energy steps covered the range of 1-30 eV and 16 steps covered energies to 30 keV. These measurements were free of backgrounds from photoelectrons, secondaries, or ionospheric plasma plumes. Three energy bands of electrons were observed: cold electrons having energies below 1 eV (plasmaspheric plumes measured by the spacecraft potential); cool electrons, defined as electrons having energies of 1-25 eV; and hot electrons having energies of 25 eV to 30 keV. The cool electron fluxes at fixed radial distances varied by an order of magnitude from one orbit to the next. These fluxes often increased with increasing radial distance, suggesting an external source. They were extremely field aligned, having pitch angle ratios (flux at 0-20° and 160-180° divided by the flux at 80-100°) greater than 100. Evidence is presented that they resulted from cusp electrons moving from open to closed magnetospheric field lines due to their E × B/B2 drift. They constituted the majority of the electron energy density at such times and places. They were not associated with magnetopause reconnection because they were not observed at the magnetopause, but they were observed as far as 3 RE inside of it. Their occurrence probability in the outer magnetosphere was 50% in June and 10% in September, suggesting a dayside source attributed to the tilt of the northern cusp toward the Sun during the summer.

  20. Semianalytical description of the modulator section of the coherent electron cooling

    NASA Astrophysics Data System (ADS)

    Elizarov, Andrey; Litvinenko, Vladimir

    2013-12-01

    In the coherent electron cooling, the modern hadron beam cooling technique, each hadron receives an individual kick from the electric field of the amplified electron density perturbation created in the modulator by this hadron in a copropagating electron beam. We developed a method for computing the dynamics of these density perturbations in an infinite electron plasma with any equilibrium velocity distribution—a possible model for the modulator. We derived analytical expressions for the dynamics of the density perturbations in the Fourier-Laplace domain for a variety of 1D, 2D, and 3D equilibrium distributions of the electron beam. To obtain the space-time dynamics, we employed the fast Fourier transform algorithm. We also found an analytical solution in the space-time domain for the 1D Cauchy equilibrium distribution, which serves as a benchmark for our general approach based on numerical evaluation of the integral transforms and as a fast alternative to the numerical computations. We tested the method for various distributions and initial conditions.

  1. Production and ion-ion cooling of highly charged ions in electron string ion source.

    PubMed

    Donets, D E; Donets, E D; Donets, E E; Salnikov, V V; Shutov, V B; Syresin, E M

    2009-06-01

    The scheme of an internal injection of Au atoms into the working space of the "Krion-2" electron string ion source (ESIS) was applied and tested. In this scheme Au atoms are evaporated from the thin tungsten wire surface in vicinity of the source electron string. Ion beams with charge states up to Au51+ were produced. Ion-ion cooling with use of C and O coolant ions was studied. It allowed increasing of the Au51+ ion yield by a factor of 2. Ions of Kr up to charge state 28+ were also produced in the source. Electron strings were first formed with injection electron energy up to 6 keV. Methods to increase the ESIS ion output are discussed.

  2. Quantifying the auroral response from measured source populations of electrons and electromagnetic wave activity

    NASA Astrophysics Data System (ADS)

    Samara, M.; Michell, R.; Grubbs, G. A., II; Davidson, R. K.; Khazanov, G. V.; Glocer, A.; Hampton, D.

    2015-12-01

    A case study is presented, where a quantitative connection is made between the measured auroral intensities and the source populations of electromagnetic waves and trapped electrons measured by THEMIS. We combine a theoretical model and high-resolution multi-spectral ground based imaging of the aurora at the THEMIS footpoint in order to interpret these data in the context of the coupled magnetosphere-ionosphere system. The THEMIS wave and particle measurements form the inputs into the Khazanov, et al., 2014 model that uses a Boltzman-Landau kinetic equation, uniformly describing the entire electron distribution function, which includes the affiliated production of secondary electrons (E < 600 eV) and their associated ionosphere-magnetosphere coupling processes. The model output will in turn be used to determine the expected auroral intensities (in Rayleighs) when considering only the primary precipitating electrons and also when both the primary and mirroring secondary electrons are included. These predicted auroral intensities will be compared to measured ones from several ground-based imagers at Poker Flat, AK, where we have high-resolution multiple emission line (557.7 nm and 427.8 nm) data at a 3.3 Hz frame rate.

  3. Attosecond Electro-Magnetic Forces Acting on Metal Nanospheres Induced By Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Lagos, M. J.; Batson, P. E.; Reyes-Coronado, A.; Echenique, P. M.; Aizpurua, J.

    2014-03-01

    Swift electron scattering near nanoscale materials provides information about light-matter behavior, including induced forces. We calculate time-dependent electromagnetic forces acting on 1-1.5 nm metal nanospheres induced by passing swift electrons, finding both impulse-like and oscillatory response forces. Initially, impulse-like forces are generated by a competition between attractive electric forces and repulsive magnetic forces, lasting a few attoseconds (5-10 as). Oscillatory, plasmonic response forces take place later in time, last a few femtoseconds (1- 5 fs), and apparently rely on photon emission by decay of the electron-induced surface plasmons. A comparison of the strength of these two forces suggests that the impulse-like behavior dominates the process, and can transfer significant linear momentum to the sphere. Our results advance understanding of the physics behind the observation of both attractive and repulsive behavior of gold nano-particles induced by electron beams in aberration-corrected electron microscopy. Work supported under DOE, Award # DE-SC0005132, Basque Gov. project ETORTEK inano, Spanish Ministerio de Ciencia e Innovacion, No. FIS2010-19609-C02-01.

  4. Macroscopic quasi-linear theory of electromagnetic electron cyclotron instability associated with core and halo solar wind electrons

    NASA Astrophysics Data System (ADS)

    Sarfraz, M.; Saeed, Sundas; Yoon, P. H.; Abbas, G.; Shah, H. A.

    2016-10-01

    Spacecraft observations made near 1 AU show that both core and halo solar wind electrons exhibit temperature anisotropies that appear to be regulated by marginal electromagnetic electron cyclotron instability condition. In the literature, the threshold conditions of this instability, operative for T⊥>T∥, have been expressed as an inverse correlation between the temperature anisotropy, T⊥/T∥, and parallel beta, β∥, but such a relation was deduced on the basis of linear stability analysis combined with empirical fitting. The present paper, on the other hand, employs macroscopic quasi-linear analysis for core-halo two-component model of the solar wind electrons, in order to follow the self-consistent time history of the core and halo temperature development as well as the dynamics of magnetic field perturbation wave energy. In the present analysis, the inverse correlation for core and halo temperature anisotropy and parallel beta naturally emerges from the solutions of self-consistent theory. The present findings indicate that the macroscopic quasi-linear method may be useful for modeling the dynamics of solar wind electrons.

  5. Laser Cooled Francium Factory for the Electron Electric Dipole Moment Search

    NASA Astrophysics Data System (ADS)

    Hayamizu, Tomohiro; Arikawa, Hiroshi; Ezure, Saki; Harada, Ken-ichi; Inoue, Takeshi; Ishikawa, Taisuke; Itoh, Masatoshi; Kato, Tomohiro; Kawamura, Hirokazu; Sato, Tomoya; Ando, Shun; Aoki, Takahiro; Kato, Ko; Uchiyama, Aiko; Aoki, Takatoshi; Furukawa, Takeshi; Hatakeyama, Atsushi; Hatanaka, Kichiji; Imai, Kenichi; Murakami, Tetsuya; Nataraj, Huliyar; Shimizu, Yasuhiro; Wakasa, Tomotsugu; Yoshida, Hidetomo; Sakemi, Yasuhiro

    A permanent electric dipole moment (EDM) of an elementary particle is a candidate observable exhibiting CP violation beyond the standard model. In the present study, we plan to search for the electron EDM in francium (Fr), which is the heaviest alkali atom, captured in a far-off resonance optical trap. Since the number of Fr atoms is essential to high precision measurements, we have developed a cold Fr source called "Laser cooled Fr factory" in order to trap the radioactive Fr produced through a nuclear fusion reaction. The Fr produced was released as an ion from a gold production target in a Fr ion source, transported as an ion beam, and converted from ion to atom in a neutralizer. The neutralized Fr atom will be trapped in a magneto-optical trap(MOT) and then be transferred to an optical dipole trap. The rate of Fr atoms so far achieved was 1 × 106 ions/sec from the ion source and 1 atom/sec of the neutralized Fr atom from the neutralizer. In order to optimize performance of the Fr beam line, Rb atoms were trapped in the MOT. In addition to the beam-line experiment, in an off-line MOT system, polarization gradient cooling was applied to the trapped Rb atoms to cool them down to temperatures lower than the Rb Doppler-cooling limit. In this paper, we describe the present status of this experimental apparatus.

  6. Radiation of de-excited electrons at large times in a strong electromagnetic plane wave

    SciTech Connect

    Kazinski, P.O.

    2013-12-15

    The late time asymptotics of the physical solutions to the Lorentz–Dirac equation in the electromagnetic external fields of simple configurations–the constant homogeneous field, the linearly polarized plane wave (in particular, the constant uniform crossed field), and the circularly polarized plane wave–are found. The solutions to the Landau–Lifshitz equation for the external electromagnetic fields admitting a two-parametric symmetry group, which include as a particular case the above mentioned field configurations, are obtained. Some general properties of the total radiation power of a charged particle are established. In particular, for a circularly polarized wave and constant uniform crossed fields, the total radiation power in the asymptotic regime is independent of the charge and the external field strength, when expressed in terms of the proper-time, and equals a half the rest energy of a charged particle divided by its proper-time. The spectral densities of the radiation power formed on the late time asymptotics are derived for a charged particle moving in the external electromagnetic fields of the simple configurations pointed above. This provides a simple method to verify experimentally that the charged particle has reached the asymptotic regime. -- Highlights: •Late time asymptotics of the solutions to the Lorentz–Dirac equation are studied. •General properties of the total radiation power of electrons are established. •The total radiation power equals a half the rest energy divided by the proper-time. •Spectral densities of radiation formed on the late time asymptotics are derived. •Possible experimental verification of the results is proposed.

  7. Hybridized Electromagnetic-Triboelectric Nanogenerator for a Self-Powered Electronic Watch.

    PubMed

    Quan, Ting; Wang, Xue; Wang, Zhong Lin; Yang, Ya

    2015-12-22

    We report a hybridized nanogenerator including a triboelectric nanogenerator (TENG) and six electromagnetic generators (EMGs) that can effectively scavenge biomechanical energy for sustainably powering an electronic watch. Triggered by the natural motions of the wearer's wrist, a magnetic ball at the center in an acrylic box with coils on each side will collide with the walls, resulting in outputs from both the EMGs and the TENG. By using the hybridized nanogenerator to harvest the biomechanical energy, the electronic watch can be continuously powered under different motion types of the wearer's wrist, where the best approach is to charge a 100 μF capacitor in 39 s to maintain the continuous operation of the watch for 456 s. To increase the working time of the watch further, a homemade Li-ion battery has been utilized as the energy storage unit for realizing the continuous working of the watch for about 218 min by using the hybridized nanogenerator to charge the battery within 32 min. This work will provide the opportunities for developing a nanogenerator-based built-in power source for self-powered wearable electronics such as an electronic watch.

  8. Dispersion characteristics of the electromagnetic waves in a relativistic electron beam guided by the ion channel

    SciTech Connect

    Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Ghasemi, Maede; Sedaghat, Zeinab; Mahdian, Zeinab

    2010-05-15

    In this article, the dispersion characteristics of the paraxial (near axis) electromagnetic (EM) waves in a relativistic electron beam guided by the ion channel are investigated. Equilibrium fields such as ion-channel electrostatic field and self-fields of relativistic electron beam are included in this formalism. In accordance with the equilibrium field structure, radial and azimuthal waves are selected as base vectors for EM waves. It is shown that the dispersion of the radially polarized EM and space charge waves are influenced by the equilibrium fields, but azimuthally polarized wave remain unaffected. In some wave number domains, the radially polarized EM and fast space charge waves are coupled. In these regions, instability is analyzed as a function of equilibrium structure. It is shown that the total equilibrium radial force due to the ion channel and electron beam and also relativistic effect play a key role in the coupling of the radially polarized EM wave and space charge wave. Furthermore, some asymptotic behaviors such as weak and strong ion channel, nonrelativistic case and cutoff frequencies are discussed. This instability could be used as an amplification mechanism for radially polarized EM waves in a beam-plasma system where a relativistic electron beam is guided by the ion channel.

  9. Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic

    SciTech Connect

    Istomin, Ya. N.; Leyser, T. B.

    2013-05-15

    Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.

  10. Electronics and Sensor Cooling with a Stirling Cycle for Venus Surface Mission

    NASA Technical Reports Server (NTRS)

    Mellott, Ken

    2004-01-01

    The inhospitable ambient surface conditions of Venus, with a 450 C temperature and 92 bar pressure, may likely require any extended-duration surface exploratory mission to incorporate some type of cooling for probe electronics and sensor devices. A multiple-region Venus mission study was completed at NASA GRC in December of 2003 that resulted in the preliminary design of a kinematically-driven, helium charged, Stirling cooling cycle with an estimated over-all COP of 0.376 to lift 100 watts of heat from a 200 C cold sink temperature and reject it at a hot sink temperature of 500 C. This paper briefly describes the design process and also describes and summarizes key features of the kinematic, Stirling cooler preliminary design concept.

  11. 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

  12. Electron interaction with the spin angular momentum of the electromagnetic field

    NASA Astrophysics Data System (ADS)

    O’Connell, R. F.

    2017-02-01

    We give a simple derivation and expansion of a recently proposed new relativistic interaction between the electron and the spin angular momentum of the electromagnetic field in quantum electrodynamics (QED). Our derivation is based on the work of Møller, who pointed out that, in special relativity, a particle with spin must always have a finite extension. After generalizing Møller’s classical result to include both rotation and quantum effects, we show that it leads to a new contribution to the energy, which is the special relativistic interaction term. In addition, we show that all relativistic terms involving spin terms arising from the Dirac equation may be obtained by this method.

  13. ELECTROMAGNETIC SIMULATIONS OF DIELECTRIC WALL ACCELERATOR STRUCTURES FOR ELECTRON BEAM ACCELERATION

    SciTech Connect

    Nelson, S D; Poole, B R

    2005-05-05

    Dielectric Wall Accelerator (DWA) technology incorporates the energy storage mechanism, the switching mechanism, and the acceleration mechanism for electron beams. Electromagnetic simulations of DWA structures includes these effects and also details of the switch configuration and how that switch time affects the electric field pulse which accelerates the particle beam. DWA structures include both bi-linear and bi-spiral configurations with field gradients on the order of 20MV/m and the simulations include the effects of the beampipe, the beampipe walls, the DWA High Gradient Insulator (HGI) insulating stack, wakefield impedance calculations, and test particle trajectories with low emittance gain. Design trade-offs include the transmission line impedance (typically a few ohms), equilibration ring optimization, driving switch inductances, and layer-to-layer coupling effects and the associated affect on the acceleration pulse's peak value.

  14. Nonlinear dispersion and transverse profile of intense electromagnetic waves, propagating through electron-positron-ion hot magnetoplasma

    SciTech Connect

    Javan, N. Sepehri Homami, S. H. H.

    2015-02-15

    Self-guided nonlinear propagation of intense circularly-polarized electromagnetic waves in a hot electron-positron-ion magnetoplasma is studied. Using a relativistic fluid model, a nonlinear equation is derived, which describes the interaction of the electromagnetic wave with the plasma in the quasi-neutral approximation. Transverse Eigen modes, the nonlinear dispersion relation and the group velocity are obtained. Results show that the transverse profile in the case of magnetized plasma with cylindrical symmetry has a radially damping oscillatory form. Effect of applying external magnetic fields, existence of the electron-positron pairs, changing the amplitude of the electromagnetic wave, and its polarization on the nonlinear dispersion relation and Eigen modes are studied.

  15. Interaction of a two-dimensional electromagnetic breather with an electron inhomogeneity in an array of carbon nanotubes

    SciTech Connect

    Zhukov, Alexander V. Bouffanais, Roland; Fedorov, E. G.; Belonenko, Mikhail B.

    2014-05-28

    Propagation of ultrashort laser pulses through various nano-objects has recently became an attractive topic for both theoretical and experimental studies due to its promising perspectives in a variety of problems of modern nanoelectronics. Here, we study the propagation of extremely short two-dimensional bipolar electromagnetic pulses in a heterogeneous array of semiconductor carbon nanotubes. Heterogeneity is defined as a region of enhanced electron density. The electromagnetic field in an array of nanotubes is described by Maxwell's equations, reduced to a multidimensional wave equation. Our numerical analysis shows the possibility of stable propagation of an electromagnetic pulse in a heterogeneous array of nanotubes. Furthermore, we establish that, depending on its speed of propagation, the pulse can pass through the area of increased electron concentration or be reflected therefrom.

  16. Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells.

    PubMed

    Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

    2016-08-08

    A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries.

  17. Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

    PubMed Central

    Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

    2016-01-01

    A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries. PMID:27499446

  18. Modelization For Electromagnetic Electron Scattering at Low Energies for Radiotherapy applications.

    NASA Astrophysics Data System (ADS)

    Nazaryan, Vahagn; Gueye, Paul

    2006-03-01

    Since release of the GEANT4 particle simulation toolkit in 2003, there has been a growing interest in its applications to medical physics. The applicability of GEANT4 to radiotherapy has been a subject of several investigations in recent years, and it was found to be of great use. Its low-energy model allows for electromagnetic interaction simulations down to 250 eV. The electron physics data are obtained from the Lawrence Livermore National Laboratory's Evaluated Electron Data Library (EEDL). At very lower energies (below 10 MeV), some of the tabulated data in EEDL have big uncertainties (more than 50%), and rely on various extrapolations to energy regions where there is no experimental data. We have investigated the variations of these cross-section data to radiotherapy applications. Our study suggests a strong need for better theoretical models of electron interactions with matter at these energies, and the necessity of new and more reliable experimental data. The progress towards such theoretical model will be presented.

  19. Unified Electromagnetic-Electronic Design of Light Trapping Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Boroumand, Javaneh; Das, Sonali; Vázquez-Guardado, Abraham; Franklin, Daniel; Chanda, Debashis

    2016-08-01

    A three-dimensional unified electromagnetic-electronic model is developed in conjunction with a light trapping scheme in order to predict and maximize combined electron-photon harvesting in ultrathin crystalline silicon solar cells. The comparison between a bare and light trapping cell shows significant enhancement in photon absorption and electron collection. The model further demonstrates that in order to achieve high energy conversion efficiency, charge separation must be optimized through control of the doping profile and surface passivation. Despite having a larger number of surface defect states caused by the surface patterning in light trapping cells, we show that the higher charge carrier generation and collection in this design compensates the absorption and recombination losses and ultimately results in an increase in energy conversion efficiency. The fundamental physics behind this specific design approach is validated through its application to a 3 μm thick functional light trapping solar cell which shows 192% efficiency enhancement with respect to the bare cell of same thickness. Such a unified design approach will pave the path towards achieving the well-known Shockley-Queisser (SQ) limit for c-Si in thin-film (<30 μm) geometries.

  20. Fraunhofer diffraction of atomic matter waves: electron transfer studies with a laser cooled target.

    PubMed

    van der Poel, M; Nielsen, C V; Gearba, M A; Andersen, N

    2001-09-17

    We have constructed an apparatus combining the experimental techniques of cold target recoil ion momentum spectroscopy and a laser cooled target. We measure angle differential cross sections in Li(+)+Na-->Li+Na(+) electron transfer collisions in the keV energy regime with a momentum resolution of 0.12 a.u. yielding an order of magnitude better angular resolution than previous measurements. We resolve Fraunhofer-type diffraction patterns in the differential cross sections. Good agreement with predictions of the semiclassical impact parameter method is obtained.

  1. The influence of longitudinal space charge fields on the modulation process of coherent electron cooling

    SciTech Connect

    Wang, G.; Blaskiewicz, M.; Litvinenko, V. N.

    2014-05-21

    Initial modulation in Coherent electron cooling (CeC) scheme relies on ion charge screening by electrons. In a CeC system with bunched electron beam, the long-range longitudinal space charge force is inevitably induced. For a relatively dense electron beam, it can be comparable or even greater than the attractive force from the ion. Hence, space-charge field influence to the modulation process could be important. If the longitudinal Debye length is much smaller than the electron bunch length, the modulation induced by the ion happens locally. In this case, the long-range longitudinal space charge field can be approximated as a uniform electric field across the region. In this paper we developed an analytical model to study the dynamics of ion shielding in the presence of a uniform electric field. We are solving the coupled Vlasov-Poisson equation system for infinite anisotropic electron plasma and estimate the influences of the longitudinal space charge field to the modulation process. We present numerical estimates for a case of the proof of CeC principle experiment at RHIC.

  2. Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling.

    PubMed

    Tokiwa, Yoshifumi; Piening, Boy; Jeevan, Hirale S; Bud'ko, Sergey L; Canfield, Paul C; Gegenwart, Philipp

    2016-09-01

    Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with (3)He gas are widely used for cooling below 1 K. However, usage of the gas has been increasingly difficult because of the current worldwide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require (3)He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1-x Sc x Co2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.

  3. Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling

    DOE PAGES

    Tokiwa, Yoshifumi; Piening, Boy; Jeevan, Hirale S.; ...

    2016-09-09

    Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with 3He gas are widely used for cooling below 1 Kelvin. However, usage of the gas has been increasingly difficult because of the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas.more » This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1$-$xScxCo2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. Lastly, this study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.« less

  4. Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling

    PubMed Central

    Tokiwa, Yoshifumi; Piening, Boy; Jeevan, Hirale S.; Bud’ko, Sergey L.; Canfield, Paul C.; Gegenwart, Philipp

    2016-01-01

    Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with 3He gas are widely used for cooling below 1 K. However, usage of the gas has been increasingly difficult because of the current worldwide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1−xScxCo2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration. PMID:27626073

  5. Self-focusing of coaxial electromagnetic beams in a plasma with electron temperature dependent electron-ion recombination coefficient

    NASA Astrophysics Data System (ADS)

    Misra, Shikha; Sodha, M. S.; Mishra, S. K.

    2017-02-01

    An analytical formulation, describing the propagation of multiple coaxial Gaussian electromagnetic (em) beams in a self-formed plasma channel with dominant collisional nonlinearity has been developed; the generation/recombination of high energy plasma particles has been considered as an additional source of plasma non-linearity in addition to Ohmic heating. Well versed paraxial approach in the vicinity of the intensity maximum has been adopted to solve the wave equation and examine the non-linear propagation of em beams while the dielectric function in the presence of the em field is determined from the balance of partial pressure gradient of electron/ion gas with the space charge field and energy balance of plasma particles. On the basis of the analysis the influence of this novel non-linearity on the propagation features like electron temperature, dielectric function and critical curves are derived numerically and graphically presented. The inclusion of this novel nonlinearity results in reduced focusing effect. The three regime characteristic features viz. oscillatory focusing/defocusing and steady divergence of beam propagation have also been worked out.

  6. An Electromagnetic Spectrum for Millennial Students: Teaching Light, Color, Energy, and Frequency Using the Electronic Devices of Our Time

    ERIC Educational Resources Information Center

    Murphy, Maureen Kendrick

    2010-01-01

    In this article, a comparison of student learning outcomes is made in sophomore-level physical science classes using a "traditional" pedagogical approach versus a "modern" approach. Specifically, when students were taught the electromagnetic spectrum using diagrams and examples that incorporate technological advances and electronic devices of our…

  7. [Dose distributions of fast electrons with an energy of 7-24 Mev in electromagnetic beam formation].

    PubMed

    Shambulov, R S; Khvan, G V; Saĭbekov, T S; Azhigaliev, N A; Shuinbekov, A D

    1983-03-01

    The formation of a wide beam is found necessary for a clinical application of a fast electron beam. A method of formation using thin dispersion foils is the most common one. An electromagnetic method of formation has been worked out, and dose distributions of fast electrons formed by this method have been compared in the tissue equivalent medium with those formed with the help of dispersion foils. The effect of some of the individual units of the forming device in these two methods of formation has been assessed. The experiment was conducted on medical beta-trons B-15 and B-5M-25 manufactured in the USSR. The depth dose distributions of fast electrons along the beam central axis in the electromagnetic formation for electrons with an energy of 7-24 MEV, field 8 X 10 cm and DSS = 90 cm are presented. It has been established that the beam intensity in the electromagnetic formation is higher than in the utilization of dispersion foils. Depth dose distribution is better in the electromagnetic formation than in the utilization of dispersion foils.

  8. Laser cooling of the AlCl molecule with a three-electronic-level theoretical model

    NASA Astrophysics Data System (ADS)

    Wan, Mingjie; Yuan, Di; Jin, Chengguo; Wang, Fanhou; Yang, Yujie; Yu, You; Shao, Juxiang

    2016-07-01

    Feasibility of laser-cooling AlCl molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the X1Σ+, a3Π, and A1Π states are studied based on multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with ACVQZ basis set, spin-orbit coupling effects are considered at the MRCI+Q level. Highly diagonally distributed Franck-Condon factors (f00 = 0.9988 and f11 = 0.9970) and branching ratios (R00 = 0.9965, R01 = 2.85 × 10-3, R02 = 6.35 × 10-4, and R03 = 2.05 × 10-6) for the A 1 Π 1 ( ν ' = 0 ) → X 1 Σ0 + + ( ν ″ = 0 ) transition are determined. A sufficiently radiative lifetime τ (A1Π1) = 4.99 ns is predicted for rapid laser cooling. The proposed cooling wavelength is deep in the ultraviolet region at λ00 = 261.75 nm. Total emission rates for the a 3 Π 0 + → X 1 Σ0 + + , a 3 Π 1 → X 1 Σ0 + + , A1Π1 → a3Π0+, and A1Π1 → a3Π1 transitions are particularly small (˜10 s-1-650 s-1). The calculated vibrational branching loss ratio to the intermediate a3Π0+ and a3Π1 states can be negligible. The results imply the probability of laser cooling AlCl molecule with three-electronic-level.

  9. Issues concerning high current lower energy electron beams required for ion cooling between EBIS LINAC and booster

    SciTech Connect

    Hershcovitch,A.

    2009-03-01

    Some issues, regarding a low energy high current electron beam that will be needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, are examined. Options for propagating such an electron beam, as well as the effect of neutralizing background plasma on electron and ion beam parameters are calculated. Computations and some experimental data indicate that none of these issues is a show stopper.

  10. Ion acoustic solitons and supersolitons in a magnetized plasma with nonthermal hot electrons and Boltzmann cool electrons

    SciTech Connect

    Rufai, O. R. Bharuthram, R.; Singh, S. V. Lakhina, G. S.

    2014-08-15

    Arbitrary amplitude, ion acoustic solitons, and supersolitons are studied in a magnetized plasma with two distinct groups of electrons at different temperatures. The plasma consists of a cold ion fluid, cool Boltzmann electrons, and nonthermal energetic hot electrons. Using the Sagdeev pseudo-potential technique, the effect of nonthermal hot electrons on soliton structures with other plasma parameters is studied. Our numerical computation shows that negative potential ion-acoustic solitons and double layers can exist both in the subsonic and supersonic Mach number regimes, unlike the case of an unmagnetized plasma where they can only exist in the supersonic Mach number regime. For the first time, it is reported here that in addition to solitions and double layers, the ion-acoustic supersoliton solutions are also obtained for certain range of parameters in a magnetized three-component plasma model. The results show good agreement with Viking satellite observations of the solitary structures with density depletions in the auroral region of the Earth's magnetosphere.

  11. Frequency-Domain Analysis of Diffusion-Cooled Hot-Electron Bolometer Mixers

    NASA Technical Reports Server (NTRS)

    Skalare, A.; McGrath, W. R.; Bumble, B.; LeDuc, H. G.

    1998-01-01

    A new theoretical model is introduced to describe heterodyne mixer conversion efficiency and noise (from thermal fluctuation effects) in diffusion-cooled superconducting hot-electron bolometers. The model takes into account the non-uniform internal electron temperature distribution generated by Wiedemann-Franz heat conduction, and accepts for input an arbitrary (analytical or experimental) superconducting resistance-versus- temperature curve. A non-linear large-signal solution is solved iteratively to calculate the temperature distribution, and a linear frequency-domain small-signal formulation is used to calculate conversion efficiency and noise. In the small-signal solution the device is discretized into segments, and matrix algebra is used to relate the heating modulation in the segments to temperature and resistance modulations. Matrix expressions are derived that allow single-sideband mixer conversion efficiency and coupled noise power to be directly calculated. The model accounts for self-heating and electrothermal feedback from the surrounding bias circuit.

  12. The design and implementation of the machine protection system for the Fermilab electron cooling facility

    SciTech Connect

    Warner, A.; Carmichael, L.; Carlson, K.; Crisp, J.; Goodwin, R.; Prost, L.; Saewert, G.; Shemyakin, A.; /Fermilab

    2009-05-01

    The Fermilab Recycler ring employs an electron cooler to store and cool 8.9-GeV antiprotons. The cooler is based on a 4.3-MV, 0.1-A, DC electrostatic accelerator for which current losses have to remain low ({approx}10{sup -5}) in order to operate reliably. The Machine Protection System (MPS) has been designed to interrupt the beam in a matter of 1-2 {micro}s when losses higher than a safe limit are detected, either in the accelerator itself or in the beam lines. This paper highlights the various diagnostics, electronics and logic that the MPS relies upon to successfully ensure that no damage be sustained to the cooler or the Recycler ring.

  13. Electron cooling system in the booster synchrotron of the HIAF project

    NASA Astrophysics Data System (ADS)

    Mao, L. J.; Yang, J. C.; Xia, J. W.; Yang, X. D.; Yuan, Y. J.; Li, J.; Ma, X. M.; Yan, T. L.; Yin, D. Y.; Chai, W. P.; Sheng, L. N.; Shen, G. D.; Zhao, H.; Tang, M. T.

    2015-06-01

    The High Intensity heavy ion Accelerator Facility (HIAF) is a new accelerator complex under design at the Institute of Modern Physics (IMP). The facility is aiming at the production of high intensity heavy ion beams for a wide range of experiments in high energy density physics, nuclear physics, atomic physics and other applications. It consists of a superconducting electron-cyclotron-resonance ion source and an intense proton ion source, a linear accelerator, a 34 Tm booster synchrotron ring, a 43 Tm multifunction compression synchrotron ring, a 13 Tm high precision spectrometer ring and several experimental terminals. A magnetized electron cooling device is supposed to be used in the booster ring for decreasing the transverse emittance of injected beams. The conceptual design and main parameters of this cooler are presented in this paper.

  14. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

    NASA Astrophysics Data System (ADS)

    Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

    2017-02-01

    Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

  15. Electron Lenses and Cooling for the Fermilab Integrable Optics Test Accelerator

    SciTech Connect

    Stancari, G.; Burov, A.; Lebedev, V.; Nagaitsev, S.; Prebys, E.; Valishev, A.

    2015-11-05

    Recently, the study of integrable Hamiltonian systems has led to nonlinear accelerator lattices with one or two transverse invariants and wide stable tune spreads. These lattices may drastically improve the performance of high-intensity machines, providing Landau damping to protect the beam from instabilities, while preserving dynamic aperture. The Integrable Optics Test Accelerator (IOTA) is being built at Fermilab to study these concepts with 150-MeV pencil electron beams (single-particle dynamics) and 2.5-MeV protons (dynamics with self fields). One way to obtain a nonlinear integrable lattice is by using the fields generated by a magnetically confined electron beam (electron lens) overlapping with the circulating beam. The required parameters are similar to the ones of existing devices. In addition, the electron lens will be used in cooling mode to control the brightness of the proton beam and to measure transverse profiles through recombination. More generally, it is of great interest to investigate whether nonlinear integrable optics allows electron coolers to exceed limitations set by both coherent or incoherent instabilities excited by space charge.

  16. Status of proof-of-principle experiment for coherent electron cooling

    SciTech Connect

    Pinayev I.; Belomestnykh, S.; Bengtsson, J.; Ben-Zvi, I.; Elizarov, A. et al

    2012-05-20

    Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o'clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters. We use a dogleg to merge the electron and ion beams. The ions 'imprint' their distribution into the electron beam via a space charge density modulation. The modulation is amplified in an FEL comprised of a 7-m long helical wiggler. The ions are co-propagating with electron beam through the FEL. The ion's average velocity is matched to the group velocity of the wave-packet of e-beam density modulation in the FEL. A three-pole wiggler at the exit of the FEL tune the phase of the wave-packet so the ion with the central energy experience the maximum of the e-beam density modulation, where electric field is zero. The time-of-flight dependence on ion's provides for the electrical field caused by the density modulation to reduce energy spread of the ion beam. The used electron beam is bent off the ion path and damped.

  17. Design of a Prototype EHD Air Pump for Electronic Chip Cooling Applications

    NASA Astrophysics Data System (ADS)

    Emmanouil, D. Fylladitakis; Antonios, X. Moronis; Konstantinos, Kiousis

    2014-05-01

    This paper presents the design, optimization and fabrication of an EHD air pump intended for high-power electronic chip cooling applications. Suitable high-voltage electrode configurations were selected and studied, in terms of the characteristics of the generated electric field, which play an important role in ionic wind flow. For this purpose, dedicated software is used to implement finite element analysis. Critical design parameters, such as the electric field intensity, wind velocity, current flow and power consumption are investigated. Two different laboratory prototypes are fabricated and their performances experimentally assessed. This procedure leads to the fabrication of a final prototype, which is then tested as a replacement of a typical fan for cooling a high power density electronic chip. To assist towards that end, an experimental thermal testing setup is designed and constructed to simulate the size of a personal computer's CPU core of variable power. The parametric study leads to the fabrication of experimental single-stage EHD pumps, the optimal design of which is capable of delivering an air flow of 51 CFM with an operating voltage of 10.5 kV. Finally, the theoretical and experimental results are evaluated and potential applications are proposed.

  18. Methods of beam cooling

    SciTech Connect

    Sessler, A.M.

    1996-02-01

    Diverse methods which are available for particle beam cooling are reviewed. They consist of some highly developed techniques such as radiation damping, electron cooling, stochastic cooling and the more recently developed, laser cooling. Methods which have been theoretically developed, but not yet achieved experimentally, are also reviewed. They consist of ionization cooling, laser cooling in three dimensions and stimulated radiation cooling.

  19. Scattering of relativistic and ultra-relativistic electrons by obliquely propagating Electromagnetic Ion Cyclotron waves

    NASA Astrophysics Data System (ADS)

    Uzbekov, Bogdan; Shprits, Yuri Y.; Orlova, Ksenia

    2016-10-01

    Electromagnetic Ion Cyclotron (EMIC) waves are transverse plasma waves that are generated in the Earth magnetosphere by ring current protons with temperature anisotropy in three different bands: below the H+, He+ and O+ ion gyrofrequencies. EMIC events are enhanced during the main phase of a geomagnetic storm when intensifications in the electric field result in enhanced injections of ions and are usually confined to high-density regions just inside the plasmapause or within drainage plumes. EMIC waves are capable of scattering radiation belt electrons and thus provide an important link between the intensification of the electric field, ion populations, and radiation belt electrons. Bounce-averaged diffusion coefficients computed with the assumption of parallel wave propagation are compared to the results of the code that uses the full cold plasma dispersion relation taking into account oblique propagation of waves and higher-order resonances. We study the sensitivity of the scattering rates to a number of included higher-order resonances, wave spectral distribution parameters, wave normal angle distribution parameters, ambient plasma density, and ion composition. Inaccuracies associated with the neglect of higher-order resonances and oblique propagation of waves are compared to potential errors introduced by uncertainties in the model input parameters.

  20. Theoretical study of electromagnetic electron cyclotron waves in the presence of AC field in Uranian magnetosphere

    NASA Astrophysics Data System (ADS)

    Pandey, R. S.; Kaur, Rajbir

    2015-10-01

    Electromagnetic electron cyclotron (EMEC) waves with temperature anisotropy in the magnetosphere of Uranus have been studied in present work. EMEC waves are investigated using method of characteristic solution by kinetic approach, in presence of AC field. In 1986, Voyager 2 encounter with Uranus revealed that magnetosphere of Uranus exhibit non-Maxwellian high-energy tail distribution. So, the dispersion relation, real frequency and growth rate are evaluated using Lorentzian Kappa distribution function. Effect of temperature anisotropy, AC frequency and number density of particles is found. The study is also extended to oblique propagation of EMEC waves in presence and absence of AC field. Through comprehensive mathematical analysis it is found that when EMEC wave propagates parallel to intrinsic magnetic field of Uranus, its growth is more enhanced than in case of oblique propagation. Results are also discussed in context to magnetosphere of Earth and also gives theoretical explanation to existence of high energetic particles observed by Voyager 2 in the magnetosphere of Uranus. The results can present a further insight into the nature of electron-cyclotron instability condition for the whistler mode waves in the outer radiation belts of Uranus or other space plasmas.

  1. Pitch-angle diffusion of electrons through growing and propagating along a magnetic field electromagnetic wave in Earth's radiation belts

    SciTech Connect

    Choi, C.-R. Dokgo, K.; Min, K.-W.; Woo, M.-H.; Choi, E.-J.; Hwang, J.; Park, Y.-D.; Lee, D.-Y.

    2015-06-15

    The diffusion of electrons via a linearly polarized, growing electromagnetic (EM) wave propagating along a uniform magnetic field is investigated. The diffusion of electrons that interact with the growing EM wave is investigated through the autocorrelation function of the parallel electron acceleration in several tens of electron gyration timescales, which is a relatively short time compared with the bounce time of electrons between two mirror points in Earth's radiation belts. Furthermore, the pitch-angle diffusion coefficient is derived for the resonant and non-resonant electrons, and the effect of the wave growth on the electron diffusion is discussed. The results can be applied to other problems related to local acceleration or the heating of electrons in space plasmas, such as in the radiation belts.

  2. Pulse length of ultracold electron bunches extracted from a laser cooled gas

    PubMed Central

    Franssen, J. G. H.; Frankort, T. L. I.; Vredenbregt, E. J. D.; Luiten, O. J.

    2017-01-01

    We present measurements of the pulse length of ultracold electron bunches generated by near-threshold two-photon photoionization of a laser-cooled gas. The pulse length has been measured using a resonant 3 GHz deflecting cavity in TM110 mode. We have measured the pulse length in three ionization regimes. The first is direct two-photon photoionization using only a 480 nm femtosecond laser pulse, which results in short (∼15 ps) but hot (∼104 K) electron bunches. The second regime is just-above-threshold femtosecond photoionization employing the combination of a continuous-wave 780 nm excitation laser and a tunable 480 nm femtosecond ionization laser which results in both ultracold (∼10 K) and ultrafast (∼25 ps) electron bunches. These pulses typically contain ∼103 electrons and have a root-mean-square normalized transverse beam emittance of 1.5 ± 0.1 nm rad. The measured pulse lengths are limited by the energy spread associated with the longitudinal size of the ionization volume, as expected. The third regime is just-below-threshold ionization which produces Rydberg states which slowly ionize on microsecond time scales.

  3. Simulation of Electron Beam Dynamics in the 22 MeV Accelerator for a Coherent Electron Cooling Proof of Principle Experiment

    SciTech Connect

    Owen, Justin

    2013-12-01

    Coherent electron cooling (CeC) offers a potential new method of cooling hadron beams in colliders such as the Relativistic Heavy Ion Collider (RHIC) or the future electron ion collider eRHIC. A 22 MeV linear accelerator is currently being built as part of a proof of principle experiment for CeC at Brookhaven National Laboratory (BNL). In this thesis we present a simulation of electron beam dynamics including space charge in the 22 MeV CeC proof of principle experiment using the program ASTRA (A Space charge TRacking Algorithm).

  4. Propagation and Generation of Electromagnetic Waves at Proton Gyrofrequencies in a Relativistic Electron-Positron Plasma. II. Excitation of Electromagnetic Waves

    NASA Astrophysics Data System (ADS)

    Zheleznyakov, V. V.; Bespalov, P. A.

    2016-04-01

    In part I of this work [1], we study the dispersion characteristics of low-frequency waves in a relativistic electron-positron plasma. In part II, we examine the electromagnetic wave instability in this plasma caused by an admixture of nonrelativistic protons with energy comparable with the energy of relativistic low-mass particles. The instability occurs in the frequency band between the fundamental harmonic of proton gyrofrequency and the fundamental harmonic of relativistic electron gyrofrequency. The results can be used for the interpretation of known observations of the pulsar emissions obtained with a high time and frequency resolution. The considered instability can probably be the initial stage of the microwave radio emission nanoshots typical of the pulsar in the Crab Nebula.

  5. Super-heavy electron material as metallic refrigerant for adiabatic demagnetization cooling

    SciTech Connect

    Tokiwa, Yoshifumi; Piening, Boy; Jeevan, Hirale S.; Bud'ko, Sergey L.; Canfield, Paul C.; Gegenwart, Philipp

    2016-09-09

    Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, because the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity, and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with 3He gas are widely used for cooling below 1 Kelvin. However, usage of the gas has been increasingly difficult because of the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. We show that a new type of refrigerant, the super-heavy electron metal YbCo2Zn20, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. This method has a number of advantages, including much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb1$-$xScxCo2Zn20 by partial Sc substitution, with x ~ 0.19. The substitution induces chemical pressure that drives the materials to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures, enabling final temperatures well below 100 mK. This performance has, up to now, been restricted to insulators. For nearly a century, the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. Lastly, this study opens new possibilities of using itinerant magnetic moments for cryogen-free refrigeration.

  6. Consumer Electronics Testing to Fast-Rise EMP (Electromagnetic Pulse) (VEMPS (Vertical Electromagnetic Pulse Simulator) 2 Development)

    DTIC Science & Technology

    1989-06-01

    complete descrip- tion of all test configurations used at FEMPS, see Erler and Dancz [7]. Three types of test data were collected throughout the test...under HDL contract DAAL02-87-C-0052 (November 1987). 7. J. Erler and J. Dancz, Consumer Electronics Updated Test Plan, Sci- ence Applications...International Corporation, SAIC-102-87-021, under HDL contract DAAL02-86-D-0041 (15 July 1987). 8. J. Erler and W. Byers, FEMPS Consumer Electronics Tests

  7. Strong neutrino cooling by cycles of electron capture and decay in neutron star crusts

    SciTech Connect

    Schatz, Hendrik; Gupta, Sanjib; Moeller, Peter; Beard, Mary; Brown, Edward; Deibel, A. T.; Gasques, Leandro; Hix, William Raphael; Keek, Laurens; Lau, Rita; Steiner, Andrew M; Wiescher, Michael

    2013-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This Urca mechanism has been studied in the context of white dwarfs13 and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models1, 2 computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface.

  8. Pumped helium system for cooling positron and electron traps to 1.2 K

    NASA Astrophysics Data System (ADS)

    Wrubel, J.; Gabrielse, G.; Kolthammer, W. S.; Larochelle, P.; McConnell, R.; Richerme, P.; Grzonka, D.; Oelert, W.; Sefzick, T.; Zielinski, M.; Borbely, J. S.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.; Müllers, A.; Walz, J.; Speck, A.

    2011-06-01

    Extremely precise tests of fundamental particle symmetries should be possible via laser spectroscopy of trapped antihydrogen ( H¯) atoms. H¯ atoms that can be trapped must have an energy in temperature units that is below 0.5 K—the energy depth of the deepest magnetic traps that can currently be constructed with high currents and superconducting technology. The number of atoms in a Boltzmann distribution with energies lower than this trap depth depends sharply upon the temperature of the thermal distribution. For example, ten times more atoms with energies low enough to be trapped are in a thermal distribution at a temperature of 1.2 K than for a temperature of 4.2 K. To date, H¯ atoms have only been produced within traps whose electrode temperature is 4.2 K or higher. A lower temperature apparatus is desirable if usable numbers of atoms that can be trapped are to eventually be produced. This report is about the pumped helium apparatus that cooled the trap electrodes of an H¯ apparatus to 1.2 K for the first time. Significant apparatus challenges include the need to cool a 0.8 m stack of 37 trap electrodes separated by only a mm from the substantial mass of a 4.2 K Ioffe trap and the substantial mass of a 4.2 K solenoid. Access to the interior of the cold electrodes must be maintained for antiprotons, positrons, electrons and lasers.

  9. Current-Induced Cooling Phenomenon in a Two-Dimensional Electron Gas Under a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Hirayama, Naomi; Endo, Akira; Fujita, Kazuhiro; Hasegawa, Yasuhiro; Hatano, Naomichi; Nakamura, Hiroaki; Shirasaki, Ryōen; Yonemitsu, Kenji

    2013-07-01

    We investigate the spatial distribution of temperature induced by a dc current in a two-dimensional electron gas (2DEG) subjected to a perpendicular magnetic field. We numerically calculate the distributions of the electrostatic potential ϕ and the temperature T in a 2DEG enclosed in a square area surrounded by insulated-adiabatic (top and bottom) and isopotential-isothermal (left and right) boundaries (with ϕ left< ϕ right and T left= T right), using a pair of nonlinear Poisson equations (for ϕ and T) that fully take into account thermoelectric and thermomagnetic phenomena, including the Hall, Nernst, Ettingshausen, and Righi-Leduc effects. We find that, in the vicinity of the left-bottom corner, the temperature becomes lower than the fixed boundary temperature, contrary to the naive expectation that the temperature is raised by the prevalent Joule heating effect. The cooling is attributed to the Ettingshausen effect at the bottom adiabatic boundary, which pumps up the heat away from the bottom boundary. In order to keep the adiabatic condition, downward temperature gradient, hence the cooled area, is developed near the boundary, with the resulting thermal diffusion compensating the upward heat current due to the Ettingshausen effect.

  10. Modulation and filamentation instability of ultrarelativistic electromagnetic waves in electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Rozina, Ch.; Tsintsade, N. L.; Maryam, N.; Komal, S.

    2016-11-01

    In this study, we have analytically investigated the effects of nonlinear Landau damping on the temporal growth rate of modulation and filamentation instabilities. Here, the nonlocal nonlinear Landau damping phenomena is appearing due to the nonlinear interaction between ultrarelativistic electromagnetic (UREM) wave (having wave vector normal to the beam) and electron-positron-ion plasma. We found that the ultrarelativistic ponderomotive force is linear, while usually it is nonlinear in relativistic case. We construct three dimensional kinetic nonlinear Schrödinger equation for a slowly varying spatio and temporal amplitude of UREM waves. The equations are then Fourier analyzed to obtain dispersion relation, which admit both modulation and filamentation instabilities. It is shown that nonlinear Landau damping is the main source of modulation instability, for a particular condition taking into account later one the maximum growth rate of modulation instability obtained as a function of amplitude of UREM waves and is displayed graphically. Further, it is shown that for an oscillating density profile, plane wave of uniform intensity becomes unstable and gets filamented. Growth rate of stationary state filament is found to be a function of amplitude of UREM waves and is emphasized that the maximum value of growth rate of filamentation instability is further increased in the presence of nonlinear Landau damping term. Finally, the growth rate of non stationary state filamentation instability is calculated and is shown that the characteristic growth length increases both with perpendicular wave vector and the amplitude of UREM waves.

  11. Standing electromagnetic solitons in hot ultra-relativistic electron-positron plasmas

    SciTech Connect

    Heidari, E.; Aslaninejad, M.; Eshraghi, H.; Rajaee, L.

    2014-03-15

    Using a one-dimensional self-consistent fluid model, we investigate standing relativistic bright solitons in hot electron-positron plasmas. The positron dynamics is taken into account. A set of nonlinear coupled differential equations describing the evolution of electromagnetic waves in fully relativistic two-fluid plasma is derived analytically and solved numerically. As a necessary condition for the existence of standing solitons the system should be relativistic. For the case of ultra-relativistic plasma, we investigate non-drifting bright solitary waves. Detailed discussions of the acceptable solutions are presented. New single hump non-trivial symmetric solutions for the scalar potential were found, and single and multi-nodal symmetric and anti-symmetric solutions for the vector potential are presented. It is shown that for a fixed value of the fluid velocity excited modes with more zeros in the profile of the vector potential show a higher magnitude for the scalar potential. An increase in the plasma fluid velocity also increases the magnitude of the scalar potential. Furthermore, the Hamiltonian and the first integral of the system are given.

  12. Oblique electromagnetic electron cyclotron waves for Kappa distribution with AC field in planetary magnetospheres

    NASA Astrophysics Data System (ADS)

    Pandey, R. S.; Kaur, Rajbir

    2015-08-01

    The dispersion relation for obliquely propagating relativistic electromagnetic electron cyclotron (EMEC) waves in collision-less magnetoplasma is obtained. Investigations for EMEC waves in magnetosphere of Jupiter, Saturn and Uranus have been done, in presence of perpendicular AC electric field for Kappa distribution function. The relativistic temporal growth rate is calculated using method of characteristic solution. Using the data provided by spacecrafts like Cassini, Voyager 1 and 2, while exploring the magnetosphere of Jupiter, Saturn and Uranus, is used to plot graphs showing growth rate being effected by various parameters. Comprehensive parametric analysis have been done at different radial distances of the planets. It is concluded that beside huge difference in magnetospheric configuration, temperature anisotropy remains the main source of energy in case of Jupiter and Uranus. While studying EMEC waves in magnetosphere of Saturn, it is inferred that growth rate attains maximum magnitude when angle of propagation increases. Also, the results and its interpretations explain how the growth of EMEC wave modifies in different magnetospheric conditions.

  13. Prototype of readout electronics for the LHAASO KM2A electromagnetic particle detectors

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Chang, Jing-Fan; Wang, Zheng; Fan, Lei

    2016-07-01

    The KM2A (one kilometer square extensive air shower array) is the largest detector array in the LHAASO (Large High Altitude Air Shower Observatory) project. The KM2A consists of 5242 EDs (Electromagnetic particle Detectors) and 1221 MDs (Muon Detectors). The EDs are distributed and exposed in the wild. Two channels, anode and dynode, are employed for the PMT (photomultiplier tube) signal readout. The readout electronics designed in this paper aims at accurate charge and arrival time measurement of the PMT signals, which cover a large amplitude range from 20 P.E. (photoelectrons) to 2 × 105 P.E. By using a “trigger-less” architecture, we digitize signals close to the PMTs. All digitized data is transmitted to DAQ (Data Acquisition) via a simplified White Rabbit protocol. Compared with traditional high energy experiments, high precision of time measurement over such a large area and suppression of temperature effects in the wild become the key techniques. Experiments show that the design has fulfilled the requirements in this project. Supported by National Natural Science Foundation of China (11375210) and the Knowledge Innovation Fund of IHEP, Beijing

  14. Electron cooling and finite potential drop in a magnetized plasma expansion

    SciTech Connect

    Martinez-Sanchez, M.; Navarro-Cavallé, J.; Ahedo, E.

    2015-05-15

    The steady, collisionless, slender flow of a magnetized plasma into a surrounding vacuum is considered. The ion component is modeled as mono-energetic, while electrons are assumed Maxwellian upstream. The magnetic field has a convergent-divergent geometry, and attention is restricted to its paraxial region, so that 2D and drift effects are ignored. By using the conservation of energy and magnetic moment of particles and the quasi-neutrality condition, the ambipolar electric field and the distribution functions of both species are calculated self-consistently, paying attention to the existence of effective potential barriers associated to magnetic mirroring. The solution is used to find the total potential drop for a set of upstream conditions, plus the axial evolution of various moments of interest (density, temperatures, and heat fluxes). The results illuminate the behavior of magnetic nozzles, plasma jets, and other configurations of interest, showing, in particular, in the divergent plasma the collisionless cooling of electrons, and the generation of collisionless electron heat fluxes.

  15. Electronic spectra of jet-cooled isoindoline: Spectroscopic determination of energy difference between conformational isomers

    NASA Astrophysics Data System (ADS)

    Tanaka, Sei'ichi; Okuyama, Katsuhiko

    2010-04-01

    The electronic spectra of jet-cooled isoindoline between the electronic ground (S0) state and the ππ ∗ lowest-excited singlet state (S1) were observed by the fluorescence excitation and single-vibronic-level dispersed fluorescence methods. The low-frequency progression due to the puckering vibration appeared in both spectra. Analysis of dispersed spectra together with geometry optimization at the level of B3LYP/6-311+G(d) indicated the presence of conformational isomers possessing axial and equatorial N-H bonds with respect to the molecular plane. The 0-0 bands of the axial and equatorial conformers were measured at 37 022 and 36 761 cm-1, respectively. Three common levels in the S1 state accessible from the respective S0-state zero levels were observed. From their transition frequencies, the S0-state energy difference between the isomers was determined to be 47.7±0.2 cm-1, where the axial conformer was more stable. In the S1 state, the energy difference was 213.7±0.2 cm-1, and the equatorial conformer was more stable. The cause of switching from a stable conformation upon excitation is discussed in terms of the electron conjugation between the π∗ orbital in benzene and the lone pair orbital of nitrogen.

  16. OTR Measurements and Modeling of the Electron Beam Optics at the E-Cooling Facility

    NASA Astrophysics Data System (ADS)

    Warner, A.; Burov, A.; Carlson, K.; Kazakevich, G.; Nagaitsev, S.; Prost, L.; Sutherland, M.; Tiunov, M.

    2006-03-01

    Optics of the electron beam accelerated in the Pelletron, intended for the electron cooling of 8.9 GeV antiprotons in the Fermilab recycler storage ring, has been studied. The beam profile parameters were measured under the accelerating section using Optical Transition Radiation (OTR) monitor. The monitor employs a highly-reflective 2 inch-diameter aluminum OTR-screen with a thickness of 5 μm and a digital CCD camera. The measurements were done in a pulse-signal mode in the beam current range of 0.03-0.8 A and at pulse durations ranging from 1 μs to 4 μs. Differential profiles measured in pulsed mode are compared with results obtained by modeling of the DC beam dynamics from the Pelletron cathode to the OTR monitor. The modeling was done with SAM, ULTRASAM and BEAM programs. An adjustment of the magnetic fields in the lenses of the accelerating section was done in the simulations. The simulated electron beam optics downstream of the accelerating section was in good agreement with the measurements made with pulsed beam.

  17. Progress towards an electron electric dipole moment measurement with laser-cooled atoms

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal

    This dissertation recounts the progress made towards a measurement of the electron electric dipole moment. The existence of a permanent electric dipole moment of any fundamental particle would imply that both time reversal and parity invariance are violated. If an electric dipole moment were measured within current experimental limits it would be the first direct evidence for physics beyond the standard model. For our measurement we use laser-cooled alkali atoms trapped in a pair of 1D optical lattices. The lattices run through three electric field plates so that the two groups of atoms see opposing electric fields. The measurement chamber is surrounded by a four layer mu-metal magnetic shield. Under electric field quantization, the atoms are prepared in a superposition of magnetic sublevels that is sensitive to the electron electric dipole moment in Ramsey-like spectroscopy. The experiment requires very large electric fields and very small magnetic fields. Engineering a system compatible with both of these goals simultaneously is not trivial. Searches for electric dipole moments using neutral atoms in optical lattices have much longer possible interaction times and potentially give more precise information about the inherent symmetry breaking than other methods. This comes at the cost of a higher sensitivity to magnetic fields and possible sources of error associated with the trapping light. If noise and systematic errors can be controlled to our design specifications our experiment will significantly improve the current experimental limit of the electron electric dipole moment.

  18. Injection method of barrier bucket supported by off-aligned electron cooling for CRing of HIAF

    NASA Astrophysics Data System (ADS)

    Shen, Guo-Dong; Yang, Jian-Cheng; Xia, Jia-Wen; Mao, Li-Jun; Yin, Da-Yu; Chai, Wei-Ping; Shi, Jian; Sheng, Li-Na; Smirnov, A.; Wu, Bo; Zhao, He

    2016-08-01

    A new accelerator complex, HIAF (the High Intensity Heavy Ion Accelerator Facility), has been approved in China. It is designed to provide intense primary and radioactive ion beams for research in high energy density physics, nuclear physics, atomic physics as well as other applications. In order to achieve a high intensity of up to 5×1011 ppp 238U34+, the Compression Ring (CRing) needs to stack more than 5 bunches transferred from the Booster Ring (BRing). However, the normal bucket to bucket injection scheme can only achieve an intensity gain of 2, so an injection method, fixed barrier bucket (BB) supported by electron cooling, is proposed. To suppress the severe space charge effect during the stacking process, off-alignment is adopted in the cooler to control the transverse emittance. In this paper, simulation and optimization with the BETACOOL program are presented. Supported by New Interdisciplinary and Advanced Pilot Fund of Chinese Academy of Sciences

  19. Air-Cooled Heat Exchanger for High-Temperature Power Electronics: Preprint

    SciTech Connect

    Waye, S. K.; Lustbader, J.; Musselman, M.; King, C.

    2015-05-06

    This work demonstrates a direct air-cooled heat exchanger strategy for high-temperature power electronic devices with an application specific to automotive traction drive inverters. We present experimental heat dissipation and system pressure curves versus flow rate for baseline and optimized sub-module assemblies containing two ceramic resistance heaters that provide device heat fluxes. The maximum allowable junction temperature was set to 175 deg.C. Results were extrapolated to the inverter scale and combined with balance-of-inverter components to estimate inverter power density and specific power. The results exceeded the goal of 12 kW/L and 12 kW/kg for power density and specific power, respectively.

  20. Modular jet impingement assemblies with passive and active flow control for electronics cooling

    DOEpatents

    Zhou, Feng; Dede, Ercan Mehmet; Joshi, Shailesh

    2016-09-13

    Power electronics modules having modular jet impingement assembly utilized to cool heat generating devices are disclosed. The modular jet impingement assemblies include a modular manifold having a distribution recess, one or more angled inlet connection tubes positioned at an inlet end of the modular manifold that fluidly couple the inlet tube to the distribution recess and one or more outlet connection tubes positioned at an outlet end of the modular manifold that fluidly coupling the outlet tube to the distribution recess. The modular jet impingement assemblies include a manifold insert removably positioned within the distribution recess and include one or more inlet branch channels each including an impinging slot and one or more outlet branch channels each including a collecting slot. Further a heat transfer plate coupled to the modular manifold, the heat transfer plate comprising an impingement surface including an array of fins that extend toward the manifold insert.

  1. Effects of electromagnetic wiggler and ion channel guiding on equilibrium orbits and waves propagation in a free electron laser

    SciTech Connect

    Amri, Hassan Ehsani; Mohsenpour, Taghi

    2016-02-15

    In this paper, an analysis of equilibrium orbits for electrons by a simultaneous solution of the equation of motion and the dispersion relation for electromagnetic wave wiggler in a free-electron laser (FEL) with ion-channel guiding has been presented. A fluid model has been used to investigate interactions among all possible waves. The dispersion relation has been derived for electrostatic and electromagnetic waves with all relativistic effects included. This dispersion relation has been solved numerically. For group I and II orbits, when the transverse velocity is small, only the FEL instability is found. In group I and II orbits with relatively large transverse velocity, new couplings between other modes are found.

  2. Electronic Combat in Space: Examining the Legality of Fielding a Space-Based Disruptive Electromagnetic Jamming System

    DTIC Science & Technology

    2007-06-15

    particles ( asteroids and meteoroids), energetic charged particles (ions, protons, electrons, etc.), and electromagnetic and ionizing radiation (x-rays...space that the US feared , and it was that sanctuary that the US sought to preserve in order to maintain relative parity on the land, sea and in the air...actions in space. This duality is not new for Americans. It began with the fear of waking up under a communist moon manifested after the launch of

  3. Improvement of the technique of identification of electrons and positrons with use of electromagnetic calorimeter of the CLAS detector

    SciTech Connect

    Gevorgyan, N. E.; Dashyan, N. B.; Paremuzyan, R. G.; Stepanyan, S. G.

    2010-01-01

    We study the dependence of the sensitivity of response of the electromagnetic calorimeter of CLAS plant on the momenta of electrons and positrons. We made calculation of this dependence and elaborated a method for its employment in identification of e- and e+. We have shown that the new method of selection of e- and e+ improves the quality of identification by about 10%. We used the experimental data obtained with the plant CLAS of linear accelerator at Jefferson laboratory (USA).

  4. Design principles and applications of a cooled CCD camera for electron microscopy.

    PubMed

    Faruqi, A R

    1998-01-01

    Cooled CCD cameras offer a number of advantages in recording electron microscope images with CCDs rather than film which include: immediate availability of the image in a digital format suitable for further computer processing, high dynamic range, excellent linearity and a high detective quantum efficiency for recording electrons. In one important respect however, film has superior properties: the spatial resolution of CCD detectors tested so far (in terms of point spread function or modulation transfer function) are inferior to film and a great deal of our effort has been spent in designing detectors with improved spatial resolution. Various instrumental contributions to spatial resolution have been analysed and in this paper we discuss the contribution of the phosphor-fibre optics system in this measurement. We have evaluated the performance of a number of detector components and parameters, e.g. different phosphors (and a scintillator), optical coupling with lens or fibre optics with various demagnification factors, to improve the detector performance. The camera described in this paper, which is based on this analysis, uses a tapered fibre optics coupling between the phosphor and the CCD and is installed on a Philips CM12 electron microscope equipped to perform cryo-microscopy. The main use of the camera so far has been in recording electron diffraction patterns from two dimensional crystals of bacteriorhodopsin--from wild type and from different trapped states during the photocycle. As one example of the type of data obtained with the CCD camera a two dimensional Fourier projection map from the trapped O-state is also included. With faster computers, it will soon be possible to undertake this type of work on an on-line basis. Also, with improvements in detector size and resolution, CCD detectors, already ideal for diffraction, will be able to compete with film in the recording of high resolution images.

  5. Low-Cost Tracking Ground Terminal Designed to Use Cryogenically Cooled Electronics

    NASA Technical Reports Server (NTRS)

    Wald, Lawrence W.; Romanofsky, Robert R.; Warner, Joseph D.

    2000-01-01

    A computer-controlled, tracking ground terminal will be assembled at the NASA Glenn Research Center at Lewis Field to receive signals transmitted by the Glenn's Direct Data Distribution (D3) payload planned for a shuttle flight in low Earth orbit. The terminal will enable direct data reception of up to two 622-megabits-per-second (Mbps) beams from the space-based, K-band (19.05-GHz) transmitting array at an end-user bit error rate of up to 10(exp -12). The ground terminal will include a 0.9-m-diameter receive-only Cassegrain reflector antenna with a corrugated feed horn incorporating a dual circularly polarized, K-band feed assembly mounted on a multiaxis, gimbaled tracking pedestal as well as electronics to receive the downlink signals. The tracking system will acquire and automatically track the shuttle through the sky for all elevations greater than 20 above the horizon. The receiving electronics for the ground terminal consist of a six-pole microstrip bandpass filter, a three-stage monolithic microwave integrated circuit (MMIC) amplifier, and a Stirling cycle cryocooler (1 W at 80 K). The Sterling cycle cryocooler cools the front end of the receiver, also known as the low-noise amplifier (LNA), to about 77 K. Cryocooling the LNA significantly increases receiver performance, which is necessary so that it can use the antenna, which has an aperture of only 0.9 m. The following drawing illustrates the cryoterminal.

  6. An experimental study of the interaction between a pulsed electron beam and a large-amplitude electromagnetic wave

    NASA Astrophysics Data System (ADS)

    Kalinin, Yu. A.; Starodubov, A. V.; Fokin, A. S.

    2015-01-01

    We experimentally investigate the interaction between an electron beam with a periodically varying diameter and a large-amplitude electromagnetic wave. The effect of different factors on the pulsed beam formation and current density in bunches is established. Compared with the electron beam deceleration circuits (low-voltage vircator systems), the generators based on pulsed turbulent beams have a broader band due to the formation of a large number of space charge bunches and an integral power efficiency that is higher by a factor of 2-2.5.

  7. The electromagnetic radiation fields of a relativistic electron avalanche with special attention to the origin of narrow bipolar pulses

    NASA Astrophysics Data System (ADS)

    Cooray, G. V.; Cooray, G. K.

    2011-12-01

    Gurevich et al. [1] postulated that the source of narrow bipolar pulses, a class of high energy pulses that occur during thunderstorms, could be a runaway electron avalanche driven by the intense electric fields of a thunderstorm. Recently, Watson and Marshall [2] used the modified transmission line model to test the mechanism of the source of narrow bipolar pulses. In a recent paper, Cooray and Cooray [3] demonstrated that the electromagnetic fields of accelerating charges could be used to evaluate the electromagnetic fields from electrical discharges if the temporal and spatial variation of the charges in the discharge is known. In the present study, those equations were utilized to evaluate the electromagnetic fields generated by a relativistic electron avalanche. In the analysis it is assumed that all the electrons in the avalanche are moving with the same speed. In other words, the growth or the decay of the number of electrons takes place only at the head of the avalanche. It is shown that the radiation is emanating only from the head of the avalanche where electrons are being accelerated. It is also shown that an analytical expression for the radiation field of the avalanche at any distance can be written directly in terms of the e-folding length of the avalanche. This makes it possible to extract directly the spatial variation of the e-folding length of the avalanche from the measured radiation fields. In the study this model avalanche was used to investigate whether it can be used to describe the measured electromagnetic fields of narrow bipolar pulses. The results obtained are in reasonable agreement with the two station data of Eack [4] for speeds of propagation around (2 - 2.5) x 10^8 m/s and when the propagation effects on the electric fields measured at the distant station is taken into account. [1] Gurevich et al. (2004), Phys. Lett. A., 329, pp. 348 -361. [2] Watson, S. S. and T. C. Marshall (2007), Geophys. Res. Lett., Vol. 34, L04816, doi: 10

  8. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Spin-dependent electron transport of a waveguide with Rashba spin-orbit coupling in an electromagnetic field

    NASA Astrophysics Data System (ADS)

    Xiao, Xian-Bo; Li, Xiao-Mao; Chen, Yu-Guang

    2009-12-01

    We investigate theoretically the spin-dependent electron transport in a straight waveguide with Rashba spin-orbit coupling (SOC) under the irradiation of a transversely polarized electromagnetic (EM) field. Spin-dependent electron conductance and spin polarization are calculated as functions of the emitting energy of electrons or the strength of the EM field by adopting the mode matching approach. It is shown that the spin polarization can be manipulated by external parameters when the strength of Rashba SOC is strong. Furthermore, a sharp step structure is found to exist in the total electron conductance. These results can be understood by the nontrivial Rashba subbands intermixing and the electron intersubband transition when a finite-range transversely polarized EM field irradiates a straight waveguide.

  9. Combined effect of constant high voltage electrostatic field and variable frequency pulsed electromagnetic field on the morphology of calcium carbonate scale in circulating cooling water systems.

    PubMed

    Zhao, Ju-Dong; Liu, Zhi-An; Zhao, Er-Jun

    2014-01-01

    Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed.

  10. Trajectories of electrons with large longitudinal momenta in the phase plane during surfatron acceleration by an electromagnetic wave

    SciTech Connect

    Mkrtichyan, G. S.

    2015-07-15

    The trajectories of electrons with large longitudinal momenta in the phase plane in the course of their surfatron acceleration by an electromagnetic wave propagating in space plasma across the external magnetic field are analyzed. Electrons with large longitudinal momenta are trapped immediately if the initial wave phase Ψ(0) on the particle trajectory is positive. For negative values of Ψ(0), no electrons trapping by the wave is observed over the available computational times. According to numerical calculations, the trajectories of trapped particles in the phase plane have a singular point of the stable focus type and the behavior of the trajectory corresponds to the motion in a complex nonstationary effective potential well. For some initial phases, electrons are confined in the region of the accelerating electric field for relatively short time, the energy gain being about 50–130% and more.

  11. Efficient Coupling of Thermal Electron Bernstein Waves to the Ordinary Electromagnetic Mode on the National Spherical Torus Experiment (NSTX)

    SciTech Connect

    G. Taylor; P.C. Efthimion; B.P. LeBlanc; M.D. Carter; J.B. Caughman; J.B. Wilgen; J. Preinhaelter; R.W. Harvey; S.A. Sabbagh

    2005-02-02

    Efficient coupling of thermal electron Bernstein waves (EBW) to ordinary mode (Omode) electromagnetic radiation has been measured in plasmas heated by energetic neutral beams and high harmonic fast waves in the National Spherical Torus Experiment (NSTX) [M. Ono, S. Kaye, M. Peng, et al., Proceedings 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol.3, p. 1135]. The EBW to electromagnetic mode coupling efficiency was measured to be 0.8 {+-} 0.2, compared to a numerical EBW modeling prediction of 0.65. The observation of efficient EBW coupling to O-mode, in relatively good agreement with numerical modeling, is a necessary prerequisite for implementing a proposed high power EBW current drive system on NSTX.

  12. Analysis of the damage threshold of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xi, Xiao-Wen; Chai, Chang-Chun; Liu, Yang; Yang, Yin-Tang; Fan, Qing-Yang; Shi, Chun-Lei

    2016-08-01

    An electromagnetic pulse (EMP)-induced damage model based on the internal damage mechanism of the GaAs pseudomorphic high electron mobility transistor (PHEMT) is established in this paper. With this model, the relationships among the damage power, damage energy, pulse width and signal amplitude are investigated. Simulation results show that the pulse width index from the damage power formula obtained here is higher than that from the empirical formula due to the hotspot transferring in the damage process of the device. It is observed that the damage energy is not a constant, which decreases with the signal amplitude increasing, and then changes little when the signal amplitude reaches up to a certain level. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  13. Experimental observations of nonlinearly enhanced 2omega-UH electromagnetic radiation excited by steady-state colliding electron beams

    NASA Technical Reports Server (NTRS)

    Intrator, T.; Hershkowitz, N.; Chan, C.

    1984-01-01

    Counterstreaming large-diameter electron beams in a steady-state laboratory experiment are observed to generate transverse radiation at twice the upper-hybrid frequency (2omega-UH) with a quadrupole radiation pattern. The electromagnetic wave power density is nonlinearly enhanced over the power density obtained from a single beam-plasma system. Electromagnetic power density scales exponentially with beam energy and increases with ion mass. Weak turbulence theory can predict similar (but weaker) beam energy scaling but not the high power density, or the predominance of the 2omega-UH radiation peak over the omega-UH peak. Significant noise near the upper-hybrid and ion plasma frequencies is also measured, with normalized electrostatic wave energy density W(ES)/n(e)T(e) approximately 0.01.

  14. New computational approaches to the N-body problem with applications to electron cooling of heavy ion beams

    NASA Astrophysics Data System (ADS)

    Abeyratne, Pulukkuttige D. Sumana

    Thomas Jefferson National Accelerator Facility (JLab) has proposed a new Electron- Ion Collider, JLEIC. In this collider, a polarized electron beam and a counter rotating ion beam collide at the interaction point(s). A critical problem for the JLEIC collider is cooling the ion beam to ensure small emittance and to achieve high luminosity. Since electron cooling --a method of cooling 'hot' ion beams through Coulomb interactions with 'cold' electron beams--is one of the most effective cooling methods, it will be used by JLEIC. However, the most naive way of calculating Coulomb forces through the pair-wise method becomes infeasible even with the most high performing computers since the computational complexity grows O(N2), where N is the number of particles as large as 1011. In this dissertation, we have developed new computational tools and a high performance computer code that allows, for the first time, a particle-based simulation of realistic electron cooling scenarios of heavy ion beams. Our toolset, collectively referred to as the Particles High-Order Adaptive Dynamics (PHAD), contains three specific tools. The first tool, the adaptive multi-level Fast Multipole Method, reduces the computational cost of computing Coulomb forces to only O(N). Our platform supports particles of any complex distribution (2D or 3D). The second tool, the Picard iteration-based integrator, resolves close encounters of particles efficiently and accurately. Finally, the third tool, the Strang operator splitting, reduces the runtime while maintaining the accuracy. The high performance code is comprised of these three main components. Although, the proposed toolset is both precise and fast, completely simulating the electron cooling of the ion beam still takes a long time on a modern computer cluster due to the millions of small time steps that needs to be simulated. In order to overcome this challenge, we have developed an MPI-parallel high performance computer code to speed up our

  15. Effect of Material Inhomogeneity on Thermal Performance of a Rheocast Aluminum Heatsink for Electronics Cooling

    NASA Astrophysics Data System (ADS)

    Payandeh, M.; Belov, I.; Jarfors, A. E. W.; Wessén, M.

    2016-06-01

    The relation between microstructural inhomogeneity and thermal conductivity of a rheocast component manufactured from two different aluminum alloys was investigated. The formation of two different primary α-Al particles was observed and related to multistage solidification process during slurry preparation and die cavity filling process. The microstructural inhomogeneity of the component was quantified as the fraction of α 1-Al particles in the primary Al phase. A high fraction of coarse solute-lean α 1-Al particles in the primary Al phase caused a higher thermal conductivity of the component in the near-to-gate region. A variation in thermal conductivity through the rheocast component of 10% was discovered. The effect of an inhomogeneous temperature-dependent thermal conductivity on the thermal performance of a large rheocast heatsink for electronics cooling in an operation environment was studied by means of simulation. Design guidelines were developed to account for the thermal performance of heatsinks with inhomogeneous thermal conductivity, as caused by the rheocasting process. Under the modeling assumptions, the simulation results showed over 2.5% improvement in heatsink thermal resistance when the higher conductivity near-to-gate region was located at the top of the heatsink. Assuming homogeneous thermo-physical properties in a rheocast heatsink may lead to greater than 3.5% error in the estimation of maximum thermal resistance of the heatsink. The variation in thermal conductivity within a large rheocast heatsink was found to be important for obtaining of a robust component design.

  16. Abnormal responses of electronic pocket dosimeters caused by high frequency electromagnetic fields emitted from digital cellular telephones.

    PubMed

    Deji, Shizuhiko; Nishizawa, Kunihide

    2005-09-01

    High frequency electromagnetic fields emitted from digital cellular telephones (cell phones) occasionally cause abnormally high and erroneous indicated dose readings on electronic pocket dosimeters (EPDs). Electric field strength distribution around a cell phone transmitting 1.5 GHz band with a maximum power of 0.8 W was analyzed by using an isotropic probe with tri-axial dipole antennas. Five types of EPDs were exposed to the fields for 50 s under configurations relative to the cell phone. The electric field distribution expanded around the phone's antenna and had a maximum electric field strength of 36.5 +/- 0.3 V m(-1). The cell phone gave rise to erroneous indicated dose readings on four out of five EPDs. The maximum value of erroneous indicated dosage for 50 s reached 1,283 microSv, which was about 2.6% of the annual effective dose limit of 50 mSv. The electromagnetic susceptibility of the EPDs was higher in the sections where the semiconductor detectors or electric circuit boards were located. The distance required to prevent electromagnetic interference differed for each EPD and ranged from 2.0 to 21.0 cm from the cell phone. The electric and magnetic field immunity levels of the EPDs varied from 9.2 V m(-1) to greater than 37.6 V m(-1), and from 0.03 A m(-1) to greater than 0.51 A m(-1). The EPDs displayed erroneous dose readings during exposure but recovered their normal performance after the cell phone ceased transmitting. The electromagnetic immunity levels of the EPDs were either equal to or greater than the IEC-standard. The immunity levels should be enhanced greater than the IEC-standard from the standpoint of radiation protection. The simplest and most reliable measure to prevent potential malfunction is to prohibit the radiation workers from carrying cell phones to their workplace.

  17. Transport-Coefficient Dependence of Current-Induced Cooling Effect in a Two-Dimensional Electron Gas

    NASA Astrophysics Data System (ADS)

    Hirayama, Naomi; Endo, Akira; Fujita, Kazuhiro; Hasegawa, Yasuhiro; Hatano, Naomichi; Nakamura, Hiroaki; Shirasaki, Ryōen; Yonemitsu, Kenji

    2012-06-01

    The dependence of the current-induced cooling effect on the electron mobility μ e is explored for a two-dimensional electron gas (2DEG) subjected to a perpendicular magnetic field. We calculate the distributions of the electrochemical potentials and the temperatures under a magnetic field, fully taking account of thermoelectric and thermomagnetic phenomena. Whereas the electrochemical potential and the electric current remain qualitatively unchanged, the temperature distribution exhibits drastic mobility dependence. The lower-mobility system has cold and hot areas at opposite corners, which results from the heat current brought about by the Ettingshausen effect in the vicinity of the adiabatic boundaries. The cooling effect is intensified by an increase in μ e. Intriguingly, the cold and hot areas change places with each other as the mobility μ e is further increased. This is because the heating current on the adiabatic edges due to the Righi-Leduc effect exceeds that due to the Ettingshausen effect in the opposite direction.

  18. 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.

  19. Apparatus and method for detecting electromagnetic radiation using electron photoemission in a micromechanical sensor

    DOEpatents

    Datskos, Panagiotis G.; Rajic, Slobodan; Datskou, Irene C.; Egert, Charles M.

    2002-01-01

    A micromechanical sensor and method for detecting electromagnetic radiation involve producing photoelectrons from a metal surface in contact with a semiconductor. The photoelectrons are extracted into the semiconductor, which causes photo-induced bending. The resulting bending is measured, and a signal corresponding to the measured bending is generated and processed. A plurality of individual micromechanical sensors can be arranged in a two-dimensional matrix for imaging applications.

  20. Electron acceleration by an electromagnetic wave propagating across a magnetic field in periodic structures

    NASA Astrophysics Data System (ADS)

    Buts, V. A.; Ognivenko, V. V.

    1990-05-01

    The possibility of the acceleration of charged particles captured by an electromagnetic wave propagating across a constant magnetic field in periodic slow-wave structures is demonstrated. A plane waveguide with perfectly conducting walls is examined as an example of an electrodynamic structure in which such an acceleration mechanism is possible. The acceleration rate is determined, and the stability of captured particle motion is investigated.

  1. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma

    SciTech Connect

    Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi

    2009-02-15

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45 GHz, 2.5 kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10 W) separate frequency (1-2.1 GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35 mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1 mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic.

  2. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma.

    PubMed

    Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi

    2009-02-01

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45 GHz, 2.5 kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10 W) separate frequency (1-2.1 GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35 mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1 mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic.

  3. FULL ELECTROMAGNETIC SIMULATION OF FREE-ELECTRON LASER AMPLIFIER PHYSICS VIA THE LORENTZ-BOOSTED FRAME APPROACH

    SciTech Connect

    Fawley, William M; Vay, Jean-Luc

    2009-04-29

    Numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame[1]. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor gamma_F , the red-shifted FEL radiation and blue shifted undulator have identical wavelengths and the number of required time-steps (presuming the Courant condition applies) decreases by a factor of 2(gamma_F)**2 for fully electromagnetic simulation. We have adapted the WARP code [2]to apply this method to several FEL problems involving coherent spontaneous emission (CSE) from pre-bunched ebeams, including that in a biharmonic undulator.

  4. Electron acceleration by an obliquely propagating electromagnetic wave in the regime of validity of the Fokker-Planck-Kolmogorov approach

    NASA Technical Reports Server (NTRS)

    Hizanidis, Kyriakos; Vlahos, L.; Polymilis, C.

    1989-01-01

    The relativistic motion of an ensemble of electrons in an intense monochromatic electromagnetic wave propagating obliquely in a uniform external magnetic field is studied. The problem is formulated from the viewpoint of Hamiltonian theory and the Fokker-Planck-Kolmogorov approach analyzed by Hizanidis (1989), leading to a one-dimensional diffusive acceleration along paths of constant zeroth-order generalized Hamiltonian. For values of the wave amplitude and the propagating angle inside the analytically predicted stochastic region, the numerical results suggest that the diffusion probes proceeds in stages. In the first stage, the electrons are accelerated to relatively high energies by sampling the first few overlapping resonances one by one. During that stage, the ensemble-average square deviation of the variable involved scales quadratically with time. During the second stage, they scale linearly with time. For much longer times, deviation from linear scaling slowly sets in.

  5. Toroidal Electromagnetic Particle-in-Cell Code with Gyro-kinetic Electron and Fully-kinetic ion

    NASA Astrophysics Data System (ADS)

    Lin, Jingbo; Zhang, Wenlu; Liu, Pengfei; Li, Ding

    2016-10-01

    A kinetic simulation model has been developed using gyro-kinetic electron and fully-kinetic ion by removing fast gyro motion of electrons using the Lie-transform perturbation theory. A particle-in-cell kinetic code is developed based on this model in general magnetic flux coordinate systems, which is particularly suitable for simulations of toroidally confined plasma. Single particle motion and field solver are successfully verified respectively. Integrated electrostatic benchmark, for example the lower-hybrid wave (LHW) and ion Bernstein wave (IBW), shows a good agreement with theoretical results. Preliminary electromagnetic benchmark of fast wave at lower hybrid frequency range is also presented. This code can be a first-principal tool to investigate high frequency nonlinear phenomenon, such as parametric decay instability, during lower-hybrid current drive (LHCD) and ion cyclotron radio frequency heating (ICRF) with complex geometry effect included. Supported by National Special Research Program of China For ITER and National Natural Science Foundation of China.

  6. Progress of a room temperature electron cyclotron resonance ion source using evaporative cooling technology at Institute of Modern Physics

    SciTech Connect

    Lu, W.; Xiong, B.; Guo, S. Q.; Cao, R.; Ruan, L.; Zhang, X. Z.; Sun, L. T.; Feng, Y. C.; Ma, B. H.; Zhao, H. W.

    2014-02-15

    A new room temperature ECR ion source, Lanzhou Electron Cyclotron Resonance ion source No. 4 (LECR4, previously named DRAGON), is under intense construction at Institute of Modern Physics. LECR4 is designed to operate with 18 GHz microwave frequency. The maximum axial magnetic fields are 2.3 T at injection and 1.3 T at extraction, and the radial field at the plasma chamber wall of 76 mm inner diameter is 1.0–1.2 T. One of the unique features for LECR4 is that its axial solenoids are winded with solid square copper wires which are immersed in a kind of special evaporative cooling medium for cooling purpose. Till now, a prototype of the cooling system has been successfully constructed and tested, which has demonstrated that the cooling efficiency of the designed system could meet the requirements of LECR4 under the routine operation conditions. All the main components of the ion source have been completed. Assembly and commissioning is ongoing. The latest developments and test results will be presented in this paper.

  7. Progress of a room temperature electron cyclotron resonance ion source using evaporative cooling technology at Institute of Modern Physics.

    PubMed

    Lu, W; Xiong, B; Zhang, X Z; Sun, L T; Feng, Y C; Ma, B H; Guo, S Q; Cao, R; Ruan, L; Zhao, H W

    2014-02-01

    A new room temperature ECR ion source, Lanzhou Electron Cyclotron Resonance ion source No. 4 (LECR4, previously named DRAGON), is under intense construction at Institute of Modern Physics. LECR4 is designed to operate with 18 GHz microwave frequency. The maximum axial magnetic fields are 2.3 T at injection and 1.3 T at extraction, and the radial field at the plasma chamber wall of 76 mm inner diameter is 1.0-1.2 T. One of the unique features for LECR4 is that its axial solenoids are winded with solid square copper wires which are immersed in a kind of special evaporative cooling medium for cooling purpose. Till now, a prototype of the cooling system has been successfully constructed and tested, which has demonstrated that the cooling efficiency of the designed system could meet the requirements of LECR4 under the routine operation conditions. All the main components of the ion source have been completed. Assembly and commissioning is ongoing. The latest developments and test results will be presented in this paper.

  8. Motion of ionized electrons under the intense electromagnetic field of the beam

    SciTech Connect

    Kamiya, Y.

    1983-09-01

    The motion of an electron ionized from residual gas by the beam becomes relativistic in the case of a high-density beam as in SLC, while the ions produced by the beam remain nonrelativistic. The ionized relativistic electron will be dragged by the beam, and will go away from the beam (electron beam) before the beam passes, even for the very short bunch of SLC. In this note, we discuss the motions of electrons ionized by the electron beam or by the positron beam. We assume that the density of the beam is uniform and the shape cylindrical (transversely round and longitudinally rectangular).

  9. The applicability range of different forms of the radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions)

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Esirkepov, T. Zh; Kando, M.; Koga, J. K.; Bulanov, S. V.

    2013-02-01

    When the effects of radiation reaction dominate the interaction of electrons with intense laser pulses, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crucially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possess unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency.

  10. Theory of hysteresis during electron heating of electromagnetic wave scattering by self-organized dust structures in complex plasmas

    SciTech Connect

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-07-15

    Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.

  11. Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability

    NASA Astrophysics Data System (ADS)

    Shaaban, S. M.; Lazar, M.; Poedts, S.; Elhanbaly, A.

    2016-06-01

    In collision-poor plasmas from space, e.g., the solar wind and planetary magnetospheres, the kinetic anisotropy of the plasma particles is expected to be regulated by the kinetic instabilities. Driven by an excess of ion (proton) temperature perpendicular to the magnetic field (T_{perp}>T_{allel}), the electromagnetic ion-cyclotron (EMIC) instability is fast enough to constrain the proton anisotropy, but the observations do not conform to the instability thresholds predicted by the standard theory for bi-Maxwellian models of the plasma particles. This paper presents an extended investigation of the EMIC instability in the presence of suprathermal electrons which are ubiquitous in these environments. The analysis is based on the kinetic (Vlasov-Maxwell) theory assuming that both species, protons and electrons, may be anisotropic, and the EMIC unstable solutions are derived numerically providing an accurate description for conditions typically encountered in space plasmas. The effects of suprathermal populations are triggered by the electron anisotropy and the temperature contrast between electrons and protons. For certain conditions the anisotropy thresholds exceed the limits of the proton anisotropy measured in the solar wind considerably restraining the unstable regimes of the EMIC modes.

  12. Integrated three-dimensional module heat exchanger for power electronics cooling

    DOEpatents

    Bennion, Kevin; Lustbader, Jason

    2013-09-24

    Embodiments discussed herein are directed to a power semiconductor packaging that removes heat from a semiconductor package through one or more cooling zones that are located in a laterally oriented position with respect to the semiconductor package. Additional embodiments are directed to circuit elements that are constructed from one or more modular power semiconductor packages.

  13. Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xiao-Wen, Xi; Chang-Chun, Chai; Gang, Zhao; Yin-Tang, Yang; Xin-Hai, Yu; Yang, Liu

    2016-04-01

    The damage effect and mechanism of the electromagnetic pulse (EMP) on the GaAs pseudomorphic high electron mobility transistor (PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900), and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  14. The spectral forms of the stimulated electromagnetic emission near the 3-rd electron gyroharmonic at the SPEAR heating facility

    NASA Astrophysics Data System (ADS)

    Yurik, Roman; Tereshchenko, Evgeny; Baddeley, Lisa

    The results of the stimulated electromagnetic emission (SEE) observations of the final heating campaign with the SPEAR (Space Plasma Exploration by Active Radar) heating facility are reported. The presented observations were carried out in November 2013 on the Spitsbergen archipelago. The SEE observations were undertaken using the Polar Geophysical Institute (PGI) HF-interferometer, situated about 30~km from SPEAR at the geophysical observatory in Barensburg. The HF interferometer was modified such that it was possible to measure the polarization parameters of the received signal. The observatory also contains additional diagnostic equipment, such as magnetometers and receiving station of the RTU PGI KSC RAS, which were also utilized during the campaign. As a result of the observations the spectral forms of steady-state stimulated electromagnetic emission were obtained when the SPEAR heating facility operate in the frequency range from 4.14 MHz to 4.26 MHz (about 0.1 off the electron gyro frequency) under the day-time conditions. Lisa Baddeley’s research is supported by the Research Council of Norway/CoE under contract 223252/F50. SPEAR is supported by the Norwegian Research Council (grant 191628). The authors acknowledge Russian Foundation for Basic Research (Grant No. 13-05-12005-OFI-M) for financial support and participants of the heating campaign.

  15. Electromagnetic Aharonov-Bohm effect in a two-dimensional electron gas ring

    NASA Astrophysics Data System (ADS)

    van der Wiel, W. G.; Nazarov, Yu. V.; de Franceschi, S.; Fujisawa, T.; Elzerman, J. M.; Huizeling, E. W.; Tarucha, S.; Kouwenhoven, L. P.

    2003-01-01

    We define a mesoscopic ring in a two-dimensional electron gas interrupted by two tunnel barriers, enabling us to apply a well-defined potential difference between the two halves of the ring. The electron interference in the ring is modified using a perpendicular magnetic field and a bias voltage. We observe clear Aharonov-Bohm oscillations up to the quantum Hall regime as a function of both parameters. The electron travel time between the barriers is found to increase with the applied magnetic field. Introducing a scattering model, we develop a method to measure the nonequilibrium electron dephasing time, which becomes very short at high voltages and magnetic fields. The relevance of electron-electron interactions is discussed.

  16. Relativistic electron precipitation events driven by electromagnetic ion-cyclotron waves

    SciTech Connect

    Khazanov, G. Sibeck, D.; Tel'nikhin, A.; Kronberg, T.

    2014-08-15

    We adopt a canonical approach to describe the stochastic motion of relativistic belt electrons and their scattering into the loss cone by nonlinear EMIC waves. The estimated rate of scattering is sufficient to account for the rate and intensity of bursty electron precipitation. This interaction is shown to result in particle scattering into the loss cone, forming ∼10 s microbursts of precipitating electrons. These dynamics can account for the statistical correlations between processes of energization, pitch angle scattering, and relativistic electron precipitation events, that are manifested on large temporal scales of the order of the diffusion time ∼tens of minutes.

  17. Self-Induced Transparency and Electromagnetic Pulse Compression in a Plasma or an Electron Beam under Cyclotron Resonance Conditions

    SciTech Connect

    Ginzburg, N. S.; Zotova, I. V.; Sergeev, A. S.

    2010-12-30

    Based on analogy to the well-known process of the self-induced transparency of an optical pulse propagating through a passive two-level medium we describe similar effects for a microwave pulse interacting with a cold plasma or rectilinear electron beam under cyclotron resonance condition. It is shown that with increasing amplitude and duration of an incident pulse the linear cyclotron absorption is replaced by the self-induced transparency when the pulse propagates without damping. In fact, the initial pulse decomposes to one or several solitons with amplitude and duration defined by its velocity. In a certain parameter range, the single soliton formation is accompanied by significant compression of the initial electromagnetic pulse. We suggest using the effect of self-compression for producing multigigawatt picosecond microwave pulses.

  18. Lorentz-Abraham-Dirac versus Landau-Lifshitz radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions).

    PubMed

    Bulanov, Sergei V; Esirkepov, Timur Zh; Kando, Masaki; Koga, James K; Bulanov, Stepan S

    2011-11-01

    When the parameters of electron-extreme power laser interaction enter the regime of dominated radiation reaction, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crucially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possesses unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency. For this, a class of the exact solutions to the nonlinear problems of charged particle motion in the time-varying electromagnetic field is used.

  19. Lorentz-Abraham-Dirac versus Landau-Lifshitz radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions)

    NASA Astrophysics Data System (ADS)

    Bulanov, Sergei V.; Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K.; Bulanov, Stepan S.

    2011-11-01

    When the parameters of electron-extreme power laser interaction enter the regime of dominated radiation reaction, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crucially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possesses unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency. For this, a class of the exact solutions to the nonlinear problems of charged particle motion in the time-varying electromagnetic field is used.

  20. Random walk study of electron motion in helium in crossed electromagnetic fields

    NASA Technical Reports Server (NTRS)

    Englert, G. W.

    1972-01-01

    Random walk theory, previously adapted to electron motion in the presence of an electric field, is extended to include a transverse magnetic field. In principle, the random walk approach avoids mathematical complexity and concomitant simplifying assumptions and permits determination of energy distributions and transport coefficients within the accuracy of available collisional cross section data. Application is made to a weakly ionized helium gas. Time of relaxation of electron energy distribution, determined by the random walk, is described by simple expressions based on energy exchange between the electron and an effective electric field. The restrictive effect of the magnetic field on electron motion, which increases the required number of collisions per walk to reach a terminal steady state condition, as well as the effect of the magnetic field on electron transport coefficients and mean energy can be quite adequately described by expressions involving only the Hall parameter.

  1. Improvement of cooling performance for electronic devices by nucleate boiling of immisible mixtures

    NASA Astrophysics Data System (ADS)

    Okayama, Satoshi; Iwata, Keisuke; Shinmoto, Yasuhisa; Ohta, Haruhiko

    2016-09-01

    The employment of immiscible mixtures in nucleate boiling improves the cooling performance drastically. Increase of CHF is possible by high subcooling of less-volatile liquid compressed by high-vapor pressure of more-volatile component. In addition, the reduction of surface temperature from that of pure less-volatile liquid is resulted from the co-existed vapor of more-volatile component. And the increase of pressure above the atmospheric keeping low liquid temperature is possible to prevent the mixing of incondensable gases. Furthermore, boiling can be initiated at lower surface temperature, which is required for the cooling of e.g. automobile inverters accompanied by large variation of thermal load. The performance of immiscible mixtures in nucleate boiling are summarized with reference to new data for Novec7100/water and FC72/ethanol and existing data obtained by the present authors.

  2. Random walk of electrons in a gas in the presence of polarized electromagnetic waves: Genesis of a wave induced discharge

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Sudeep; Paul, Samit

    2009-10-01

    The average number of collisions N of seed electrons with neutral gas atoms during random walk in escaping from a given volume, in the presence of polarized electromagnetic waves, is found to vary as N =B(Λ /λ)2/[1+C(Λ /λ)]2, indicating a modification to the conventional field free square law N =A(Λ /λ)2, where Λ is the characteristic diffusion length and λ the mean free path. It is found that for the field free case A =1.5 if all the electrons originate at the center and is 1.25 if they are allowed to originate at any random point in the given volume. The B and C coefficients depend on the wave electric field and frequency. Predictions of true discharge initiation time τc can be made from the temporal evolution of seed electrons over a wide range of collision frequencies. For linearly polarized waves of 2.45 GHz and electric field in the range (0.6-1.0)×105 V/m, τc=5.5-1.6 ns for an unmagnetized microwave driven discharge at 1 Torr argon.

  3. Electron random walk and collisional crossover in a gas in presence of electromagnetic waves and magnetostatic fields

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Sudeep; Dey, Indranuj; Paul, Samit

    2013-04-01

    This paper deals with random walk of electrons and collisional crossover in a gas evolving toward a plasma, in presence of electromagnetic (EM) waves and magnetostatic (B) fields, a fundamental subject of importance in areas requiring generation and confinement of wave assisted plasmas. In presence of EM waves and B fields, the number of collisions N suffered by an electron with neutral gas atoms while diffusing out of the volume during the walk is significantly modified when compared to the conventional field free square law diffusion; N =1.5(Λ /λ)2, where Λ is the characteristic diffusion length and λ is the mean free path. There is a distinct crossover and a time scale associated with the transition from the elastic to inelastic collisions dominated regime, which can accurately predict the breakdown time (τc) and the threshold electric field (EBD) for plasma initiation. The essential features of cyclotron resonance manifested as a sharp drop in τc, lowering of EBD and enhanced electron energy gain is well reproduced in the constrained random walk.

  4. Thermal Analysis and Design of Air Cooled Electronic Circuit Boards Using a Desktop Computer.

    DTIC Science & Technology

    1980-06-01

    tabular and graphical. By using internal selection of heat transfer corre- lations, the THERMELEX system depends only on input of physical parameters...only on input of physical parameters for thermal predictions. 4 TABLE OF CONTENTS I. INTRODUCTION---------------------------------------- 13 A...depending only on natural circulation for cooling. The major emphasis over the last 15 years has been a continuing effort toward a reduction in physical

  5. Electromagnetic cyclotron-loss-cone instability associated with weakly relativistic electrons

    NASA Technical Reports Server (NTRS)

    Wong, H. K.; Wu, C. S.; Ke, F. J.; Schneider, R. S.; Ziebell, L. F.

    1982-01-01

    The amplification of fast extraordinary mode waves at frequencies very close to the electron cyclotron frequency, due to the presence of a population of energetic electrons with a loss-cone type distribution, is studied. Low-energy background electrons are included in the analysis. Two types of loss-cone distribution functions are considered, and it is found that the maximum growth rates for both distribution functions are of the same order of magnitude. When the thermal effects of the energetic electrons are included in the dispersion equation, the real frequencies of the waves are lower than those obtained by using the cold plasma approximation. This effect tends to enhance the growth rate. An idealized case including a parallel electric field such that the distribution function of the trapped energetic electrons is modified is also considered. It is assumed that the parallel electric field can remove the low-energy background electrons away from the source region of radiation. Both these effects increase the growth rate.

  6. Adsorption behavior of beryllium(II) on copper-oxide nanoparticles dispersed in water: A model for (7)Be colloid formation in the cooling water for electromagnets at high-energy accelerator facilities.

    PubMed

    Bessho, Kotaro; Kanaya, Naoki; Shimada, Saki; Katsuta, Shoichi; Monjushiro, Hideaki

    2014-01-01

    The adsorption behavior of Be(II) on CuO nanoparticles dispersed in water was studied as a model for colloid formation of radioactive (7)Be nuclides in the cooling water used for electromagnets at high-energy proton accelerator facilities. An aqueous Be(II) solution and commercially available CuO nanoparticles were mixed, and the adsorption of Be(II) on CuO was quantitatively examined. From a detailed analysis of the adsorption data measured as a function of the pH, it was confirmed that Be(II) is adsorbed on the CuO nanoparticles by complex formation with the hydroxyl groups on the CuO surface (>S-OH) according to the following equation: n > S-OH + Be(2+) ⇔ (>S-O)n Be((2-n)+) + nH(+) (n = 2, 3) S : solid surface. The surface-complexation constants corresponding to the above equilibrium, β(s,2) and β(s,3), were determined for four types of CuO nanoparticles. The β(s,2) value was almost independent of the type of nanoparticle, whereas the β(s,3) values varied with the particle size. These complexation constants successfully explain (7)Be colloid formation in the cooling water used for electromagnets at the 12-GeV proton accelerator facility.

  7. Ultrafast Relaxation Dynamics of Photoexcited Heme Model Compounds: Observation of Multiple Electronic Spin States and Vibrational Cooling.

    PubMed

    Govind, Chinju; Karunakaran, Venugopal

    2017-04-04

    Hemin is a unique model compound of heme proteins carrying out variable biological functions. Here, the excited state relaxation dynamics of heme model compounds in the ferric form are systematically investigated by changing the axial ligand (Cl/Br), the peripheral substituent (vinyl/ethyl-meso), and the solvent (methanol/DMSO) using femtosecond pump-probe spectroscopy upon excitation at 380 nm. The relaxation time constants of these model compounds are obtained by global analysis. Excited state deactivation pathway of the model compounds comprising the decay of the porphyrin excited state (S*) to ligand to metal charge transfer state (LMCT, τ1), back electron transfer from metal to ligand (MLCT, τ2), and relaxation to the ground state through different electronic spin states of iron (τ3 and τ4) are proposed along with the vibrational cooling processes. This is based on the excited state absorption spectral evolution, similarities between the transient absorption spectra of the ferric form and steady state absorption spectra of the low-spin ferrous form, and the data analysis. The observation of an increase of all the relaxation time constants in DMSO compared to the methanol reflects the stabilization of intermediate states involved in the electronic relaxation. The transient absorption spectra of met-myoglobin are also measured for comparison. Thus, the transient absorption spectra of these model compounds reveal the involvement of multiple iron spin states in the electronic relaxation dynamics, which could be an alternative pathway to the ground state beside the vibrational cooling processes and associated with the inherent features of the heme b type.

  8. Ion Gyro-Harmonic Structuring in the Stimulated Electromagnetic Emission Spectrum During Second Electron Gyro-Harmonic Heating

    NASA Astrophysics Data System (ADS)

    Scales, Wayne; Bernhardt, Paul; Samimi, Alireza; Bricinsky, Stanley; Selcher, Craig

    2012-07-01

    Recent observations of Stimulated Electromagnetic Emissions SEEs have shown structures ordered by the ion gyro-frequency. In particular, during experiments in which the heating frequency is near the second electron gyro-harmonic, unique discrete spectral features separated by the ion gyro-frequency have been observed within about 1 kHz of the pump frequency. On occasion, a broadband spectral feature near 500 Hz is observed that coexists with the ion gyro-harmonic spectral features. Explanations for these spectral features have been based on parametric decay of the pump field into upper hybrid/electron Bernstein and ion Bernstein and oblique ion acoustic waves at the upper hybrid layer. This presentation will first review important characteristics of these ion gyro-harmonic spectral features obtained during some recent experiments at the High Frequency Active Auroral Research HAARP facility. These characteristics are then compared to predications of an analytical model for three-wave parametric decay of the pump field into upper hybrid/electron Bernstein and ion Bernstein and oblique ion acoustic waves. It is shown from the analytical theory that important pump field parameters that influence the spectral characteristics include the angle of the pump field relative the background magnetic field, the frequency of the pump relative to the second gyro-harmonic, and the pump field strength. Two Dimensional Particle-In-Cell simulations are used to investigate aspects of the nonlinear evolution such as irregularity development and field aligned electron heating in more detail. These simulations show favorable comparisons with the analytical theory predications as well as the experimental observations. Finally, possibilities for utilizing the experimentally observed SEE spectra for diagnostic purposes are discussed.

  9. Electromagnetic interchange-like mode and zonal flow in electron-magnetohydrodynamic plasma

    SciTech Connect

    Chakrabarti, Nikhil; Horiuchi, Ritoku

    2006-10-15

    A numerical simulation of the nonlinear state of interchange instability associated with electron inertia in an unmagnetized plasma is studied. It is shown that a self-consistent sheared transverse electron current flow is generated due to nonlinear mechanisms. This zonal flow can reduce the growth rate of the magnetic interchange-like instability and reach a steady state. The zonal flow generation mechanisms are discussed by truncated Fourier mode representation. In the truncated model, three mode equations are considered that have an exact analytic solution that matches well with the numerical solution. The effect of different boundary conditions in such investigations is also discussed.

  10. APPLICATIONS OF LASERS AND OTHER TOPICS IN LASER PHYSICS AND TECHNOLOGY: Emission of surface electromagnetic waves in the case of resonance tunneling of electrons

    NASA Astrophysics Data System (ADS)

    Belenov, É. M.; Luskinovich, P. N.; Romanenko, V. I.; Sobolev, A. G.; Uskov, A. V.

    1987-10-01

    A calculation is made of the spectral density of the intensity of surface electromagnetic waves excited by the passage of a current across metal-barrier-metal tunnel structures when there are quantum potential wells inside the barrier. It is shown that quasilevels in these quantum wells give rise to narrow peaks in the spectrum of the excited surface electromagnetic waves and that the quantum efficiency of the excitation of such waves by tunneling electrons can reach unity. The peak positions can be controlled by altering the voltage across a tunnel structure.

  11. Shaping of nested potentials for electron cooling of highly-charged ions in a cooler Penning trap

    NASA Astrophysics Data System (ADS)

    Paul, Stefan; Kootte, Brian; Lascar, Daniel; Gwinner, Gerald; Dilling, Jens; Titan Collaboration

    2016-09-01

    TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) is dedicated to mass spectrometry and decay spectroscopy of short-lived radioactive nuclides in a series of ion traps including a precision Penning trap. In order to boost the achievable precision of mass measurements TITAN deploys an Electron Beam Ion Trap (EBIT) providing Highly-Charged Ions (HCI). However, the charge breeding process in the EBIT leads to an increase in the ion bunch's energy spread which is detrimental to the overall precision gain. To reduce this effect a new cylindrical Cooler PEnning Trap (CPET) is being commissioned to sympathetically cool the HCI via a simultaneously trapped electron plasma. Simultaneous trapping of ions and electrons requires a high level of control over the nested potential landscape and sophisticated switching schemes for the voltages on CPET's multiple ring electrodes. For this purpose, we are currently setting up a new experimental control system for multi-channel voltage switching. The control system employs a Raspberry Pi communicating with a digital-to-analog board via a serial peripheral interface. We report on the implementation of the voltage control system and its performance with respect to electron and ion manipulation in CPET. University of British Columbia, Vancouver, BC, Canada.

  12. Contributions to the second workshop on medium energy electron cooling - MEEC96

    SciTech Connect

    MacLachlan, J.

    1997-09-01

    MEEC96 was a workshop devoted primarily to discussion within four working groups, not a mini-conference of prepared reports. Therefore, although there are contributions bearing the name of a single author, much of what was learned came in extemporaneous discussion of the issues posed to the participants. The original plan to produce formal proceedings has been dropped because of the limited number of participants willing to write up their own contributions and because of the difficulty of converting free-wheeling discussion to the written word. The premsise for the 1996 gathering was to set a critique of Fermilab`s R&D effort at cooling a ring of 8 GeV {bar p}`s. Separate abstracts have been submitted to the energy database for contributions to this workshop.

  13. Development of an electric field application system with transparent electrodes towards the electron EDM measurement with laser-cooled Fr atoms

    NASA Astrophysics Data System (ADS)

    Ishikawa, Taisuke; Ando, Shun; Aoki, Takahiro; Arikawa, Hiroshi; Harada, Ken-Ichi; Hayamizu, Tomohiro; Inoue, Takeshi; Itoh, Masatoshi; Kawamura, Hirokazu; Kato, Ko; Sakamoto, Kosuke; Uchiyama, Aiko; Sakemi, Yasuhiro

    2014-09-01

    The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. This work is supported by Grants-in-Aid for Scientific Research (No. 26220705) and Tohoku University's Focused Research Project.

  14. Toward sub-Kelvin resistive cooling and non destructive detection of trapped non-neutral electron plasma

    NASA Astrophysics Data System (ADS)

    Di Domizio, S.; Krasnický, D.; Lagomarsino, V.; Testera, G.; Vaccarone, R.; Zavatarelli, S.

    2015-01-01

    A resonant circuit tuned to a particular frequency of the motion of charged particles stored in a Penning trap and connected to a low noise amplifier allows, at the same time, cooling and non destructive detection of the particles. Its use is widely diffused when single or few particles are stored near the centre of a hyperbolic Penning trap. We present a consistent model that predicts the shape of the induced signal when the tuned circuit is used to detect and cool the axial motion of a cold non neutral plasma stored in an open-ended cylindrical Penning trap. The model correctly accounts for the not negligible axial plasma size. We show that the power spectrum of the signal measured across the tuned circuit provides information about the particle number and insights about the plasma temperature. We report on the design of a HEMT-based cryogenic amplifier working at 14.4 MHz and 4.2 K and the results of the noise measurements. We have measured a drain current noise in the range from 6 to 17 pA/√Hz, which corresponds to an increase of the tuned circuit equivalent temperature of at maximum 0.35 K. The cryogenic amplifier has a very low power consumption from few tens to few hundreds of μW corresponding to a drain current in the range 100-800 μ A. An additional contribution due to the gate noise has been identified when the drain current is below 300 μA above that value an upper limit of the increase of the equivalent tuned circuit temperature due to this contribution of 0.02 K has been obtained. These features make the tuned circuit connected to this amplifier a promising device for detecting and cooling the axial motion of an electron plasma when the Penning trap is mounted inside a dilution refrigerator.

  15. Electromagnetic acceleration of material from a plate hit by a pulsed electron beam

    SciTech Connect

    Garcia, M.

    1998-04-16

    An intense pulsed electron beam traversing a thin metal plate creates a volume of dense plasma. Current flows in this plasma as a result of the charge and magnetic field introduced by the relativistic electrons. A magnetic field may linger after the electron beam pulse because of the conductivity of the material. This field decays by both diffusing out of the conducting matter and causing it to expand. If the magnetized matter is of low density and high conductivity it may expand quickly. Scaling laws for this acceleration are sought by analyzing the idealization of a steady axisymmetric flow. This case simplifies a general formulation based on both Euler`s and Maxwell`s equations. As an example, fluid with conductivity {sigma} = 8 x 10{sup 4} Siemens/m, density {rho} = 8 x 10{sup -3} kg/m{sup 3}, and initially magnetized to B = 1 Tesla can accelerate to v = 10{sup 4} m/s within a distance comparable to L = 1 mm and a time comparable to {sigma}{mu}L{sup 2} = 100 ns, which is the magnetic diffusion time. If instead, {sigma} = 8 x 10{sup 3} Siemens/m and {rho} = 8 x 10{sup -5} kg/m{sup 3} then v = 10{sup 5} m/s with a magnetic diffusion time {sigma}{mu}L{sup 2} = 10 ns. These idealized flows have R{sub M} = {sigma}{mu}vL = 1, where R{sub M} is the magnetic Reynolds number. The target magnetizes by a thermal electric effect.

  16. Kinetic description of a free electron laser with an electromagnetic-wave wiggler and ion-channel guiding by using the Einstein coefficient technique

    NASA Astrophysics Data System (ADS)

    Mehdian, H.; AbasiRostami, S.; Hasanbeigi, A.

    2016-04-01

    A theoretical study of electron trajectories and gain in a free electron laser (FEL) with an electromagnetic-wave wiggler and ion-channel guiding is presented based on the Einstein coefficient method. The laser gain in the low-gain regime is obtained for the case of a cold tenuous relativistic electron beam, where the beam plasma frequency is much less than the radiation frequency propagating in this configuration. The resulting gain equation is analyzed numerically over a wide range of system parameters.

  17. Photodetachment, electron cooling, and recombination, in a series of neat aliphatic room temperature ionic liquids.

    PubMed

    Molins i Domenech, Francesc; Healy, Andrew T; Blank, David A

    2015-08-14

    Transient absorption following photodetachment of a series of neat methyl-alkyl-pyrrolidinium bis(trifluoromethylsulfonyl)amides at 6.20 eV was measured with sub-picosecond time resolution in the visible and near-IR portions of the spectrum. This series spans the onset of structuring in the liquids in the form of polarity alternation. Excitation promotes the electron into a delocalized state with a very large reactive radius. Strong transient absorption is observed in the visible spectrum with a ∼700 fs lifetime, and much weaker, long-lived absorption is observed in the near-IR spectrum. Absorption in the visible is shown to be consistent with the hole, and absorption in the near-IR is assigned to the free solvated electron. Yield of free electrons is estimated at ∼4%, is insensitive to the size of the cation, and is determined in less than 1 ps. Solvation of free electrons depends strongly on the size of the cation and correlates well with the viscosity of the liquid. In addition to radiolytic stability of the aliphatic cations, ultrafast, efficient recombination of separated charge in NTf2 (-) based ionic liquids following photo-excitation near the band-gap may prevent subsequent reactive damage associated with anions.

  18. Dynamic changes of emitting electron distribution in the jet of 3C 279: signatures of acceleration and cooling

    NASA Astrophysics Data System (ADS)

    Yan, Dahai; He, Jianjian; Liao, Jinyuan; Zhang, Li; Zhang, Shuang-Nan

    2016-02-01

    We study the dynamic changes of electron energy distribution (EED) through systematically analysing the quasi-simultaneous spectral energy distributions (SEDs) of the flat spectrum radio quasar 3C 279 in different states. With Markov chain Monte Carlo technique we model fourteen SEDs of 3C 279 using a leptonic model with a three-parameter log-parabola EED. The 14 SEDs can be satisfactorily fitted with the one-zone leptonic model. The observed γ rays in 13 states are attributed to Compton scattering of external infrared photons from a surrounding dusty torus. The curved γ ray spectrum observed during 2014 2-8 April is well explained by the external Compton of dust radiation. It is found that there is a clear positive correlation between the curvature parameter b of the EED and the electron peak energy γ ^' }_pk. No significant correlation between b and the synchrotron peak frequency νs is found, due to the varied product of Doppler factor and fluid magnetic field from state to state. We interpret the correlation of b-γ ^' }_pk in a stochastic acceleration scenario. This positive correlation is in agreement with the prediction in the stage when the balance between acceleration and radiative cooling of the electrons is nearly established in the case of the turbulence spectral index q = 2.

  19. Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling

    SciTech Connect

    Grapes, Michael D.; LaGrange, Thomas; Reed, Bryan W.; Campbell, Geoffrey H.; Friedman, Lawrence H.; LaVan, David A.; Weihs, Timothy P.

    2014-08-15

    Nanocalorimetry is a chip-based thermal analysis technique capable of analyzing endothermic and exothermic reactions at very high heating and cooling rates. Here, we couple a nanocalorimeter with an extremely fast in situ microstructural characterization tool to identify the physical origin of rapid enthalpic signals. More specifically, we describe the development of a system to enable in situ nanocalorimetry experiments in the dynamic transmission electron microscope (DTEM), a time-resolved TEM capable of generating images and electron diffraction patterns with exposure times of 30 ns–500 ns. The full experimental system consists of a modified nanocalorimeter sensor, a custom-built in situ nanocalorimetry holder, a data acquisition system, and the DTEM itself, and is capable of thermodynamic and microstructural characterization of reactions over a range of heating rates (10{sup 2} K/s–10{sup 5} K/s) accessible by conventional (DC) nanocalorimetry. To establish its ability to capture synchronized calorimetric and microstructural data during rapid transformations, this work describes measurements on the melting of an aluminum thin film. We were able to identify the phase transformation in both the nanocalorimetry traces and in electron diffraction patterns taken by the DTEM. Potential applications for the newly developed system are described and future system improvements are discussed.

  20. On the use of a small-scale two-phase thermosiphon to cool high-power electronics

    NASA Astrophysics Data System (ADS)

    Schrage, D. S.

    1990-01-01

    An experimental and analytical investigation of the steady-state thermal-hydraulic operating characteristics of a small-scale two-phase thermosiphon cooling actual power electronics are presented. Boiling heat transfer coefficients and circulation mass velocities were measured while varying heat load and pressure. Both a plain and augmented riser structure, utilizing micro-fins and reentrant cavities, were simultaneously tested. The boiling heat transfer coefficients increased with both increasing heat load and pressure. The mass velocity increased with increasing pressure while both increasing and then decreasing with increasing heat load. The reentrant cavity enhancement factor, a ratio of the augmented-to-plain riser nucleate boiling heat transfer coefficients, ranged from 1 to 1.4. High-speed photography revealed bubbly, slug, churn, wispy-annular and annular flow patterns. The experimental mass velocity and heat transfer coefficient data were compared to an analytical model with average absolute deviations of 16.3 and 26.3 percent, respectively.

  1. Neutrinos from SN 1987A - Implications for cooling of the nascent neutron star and the mass of the electron antineutrino

    NASA Technical Reports Server (NTRS)

    Loredo, Thomas J.; Lamb, Don Q.

    1989-01-01

    Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.

  2. The effects of electromagnetic field on the microstructure of seminal vesicles in rat: a light and transmission electron microscope study.

    PubMed

    Khaki, Amir Afshin; Zarrintan, Sina; Khaki, Arash; Zahedi, Afshin

    2008-03-01

    In the industrial world, almost everyone is unavoidably exposed to ambient electromagnetic field (EMF) generated from various technical and household appliances. Controversy exists about the effects of EMF on various tissues of the living bodies. Seminal vesicles as one of these accessory glands play an important role in natural seminal fluid formation and the effects of EMF on its tissue is worthy of investigation. In order to examine this 30 rat were selected and kept for one weeks in quarantine and 15 (experimental group) were exposed to 50 Hz (non-ionizing radiation) during postnatal life for 2 months. The materials were processed and observed under a light and transmission electron microscope. In the experimental rats epithelial and basal cells showed significant destructions presented by heterochromatin and dense nuclei. Cell debris and abnormal areas was recognizable in the stromal connective tissue. Obvious vacuolization was present within the epithelial cell cytoplasm and also between the cellular organelles. The nuclei of the endothelial cells of the blood vessels were more rigid and endothelial cell cytoplasm contained a lot of vacuoles and pinoctotic vesicles. The results suggested that EMF exposure may cause profound changes in the vesicle seminal tissues. Therefore exposure to EMF may result in pathological changes that lead to sub fertility and infertility.

  3. Electromagnetic envelope solitons in ultrarelativistic inhomogeneous electron-positron-ion plasma

    SciTech Connect

    Du, Hong-E; Cheng, Li-Hong; Yu, Zi-Fa; Xue, Ju-Kui

    2014-08-15

    The nonlinear interaction of ultra-intense short laser beam and homogeneous/inhomogeneous electron-positron-ion (e-p-i) plasma is investigated. It is found that soliton solutions can exist in both homogeneous and inhomogeneous e-p-i plasma. The influence of the positron density, the phase velocity, the inhomogeneity nature, and the Hamiltonian of the system on the soliton structure is investigated. The evolution of envelope solitons in homogeneous e-p-i plasma is analyzed analytically by using a two-time-scale method and confirmed by numerical simulations. However, the soliton solutions can exist in inhomogeneous e-p-i plasma only when the positron density is high enough. Furthermore, the phase diagram for existing envelope soliton in positron density and phase velocity of the wave plane is obtained.

  4. Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping.

    PubMed

    Stockem, A; Grismayer, T; Fonseca, R A; Silva, L O

    2014-09-05

    A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ∼10(4)ωpe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

  5. The development of a room temperature electron cyclotron resonance ion source (Lanzhou electron cyclotron resonance ion source No. 4) with evaporative cooling technology at Institute of Modern Physics

    NASA Astrophysics Data System (ADS)

    Lu, W.; Sun, L. T.; Qian, C.; Guo, J. W.; Fang, X.; Feng, Y. C.; Yang, Y.; Ma, H. Y.; Zhang, X. Z.; Ma, B. H.; Xiong, B.; Guo, S. Q.; Ruan, L.; Zhao, H. W.

    2015-04-01

    LECR4 (Lanzhou electron cyclotron resonance ion source No. 4) has been successfully constructed at IMP and has also been connected with the Low Energy Beam Transport (LEBT) and Radio Frequency Quadrupole (RFQ) systems. These source magnet coils are cooled through evaporative cooling technology, which is the first attempt with an ECR ion source in the world. The maximum mirror field is 2.5 T (with iron plug) and the effective plasma chamber volume is 1.2 l. It was designed to be operated at 18 GHz and aimed to produce intense multiple charge state heavy ion beams for the linear injector project SSC-Linac at IMP. In February 2014, the first analyzed beam at 18 GHz was extracted. During about three months' commissioning, some outstanding results have been achieved, such as 1.97 emA of O6+, 1.7 emA of Ar8+, 1.07 emA of Ar9+, and 118 euA of Bi28+. The source has also successfully delivered O5+ and Ar8+ ion beams for RFQ commissioning in April 2014. This paper will give a brief overview of the design of LECR4. Then, the latest results of this source at 18 GHz will be presented.

  6. The development of a room temperature electron cyclotron resonance ion source (Lanzhou electron cyclotron resonance ion source No. 4) with evaporative cooling technology at Institute of Modern Physics

    SciTech Connect

    Lu, W. Sun, L. T.; Qian, C.; Feng, Y. C.; Ma, H. Y.; Zhang, X. Z.; Ma, B. H.; Zhao, H. W.; Guo, J. W.; Fang, X.; Yang, Y.; Xiong, B.; Guo, S. Q.; Ruan, L.

    2015-04-15

    LECR4 (Lanzhou electron cyclotron resonance ion source No. 4) has been successfully constructed at IMP and has also been connected with the Low Energy Beam Transport (LEBT) and Radio Frequency Quadrupole (RFQ) systems. These source magnet coils are cooled through evaporative cooling technology, which is the first attempt with an ECR ion source in the world. The maximum mirror field is 2.5 T (with iron plug) and the effective plasma chamber volume is 1.2 l. It was designed to be operated at 18 GHz and aimed to produce intense multiple charge state heavy ion beams for the linear injector project SSC-Linac at IMP. In February 2014, the first analyzed beam at 18 GHz was extracted. During about three months’ commissioning, some outstanding results have been achieved, such as 1.97 emA of O{sup 6+}, 1.7 emA of Ar{sup 8+}, 1.07 emA of Ar{sup 9+}, and 118 euA of Bi{sup 28+}. The source has also successfully delivered O{sup 5+} and Ar{sup 8+} ion beams for RFQ commissioning in April 2014. This paper will give a brief overview of the design of LECR4. Then, the latest results of this source at 18 GHz will be presented.

  7. The development of a room temperature electron cyclotron resonance ion source (Lanzhou electron cyclotron resonance ion source No. 4) with evaporative cooling technology at Institute of Modern Physics.

    PubMed

    Lu, W; Sun, L T; Qian, C; Guo, J W; Fang, X; Feng, Y C; Yang, Y; Ma, H Y; Zhang, X Z; Ma, B H; Xiong, B; Guo, S Q; Ruan, L; Zhao, H W

    2015-04-01

    LECR4 (Lanzhou electron cyclotron resonance ion source No. 4) has been successfully constructed at IMP and has also been connected with the Low Energy Beam Transport (LEBT) and Radio Frequency Quadrupole (RFQ) systems. These source magnet coils are cooled through evaporative cooling technology, which is the first attempt with an ECR ion source in the world. The maximum mirror field is 2.5 T (with iron plug) and the effective plasma chamber volume is 1.2 l. It was designed to be operated at 18 GHz and aimed to produce intense multiple charge state heavy ion beams for the linear injector project SSC-Linac at IMP. In February 2014, the first analyzed beam at 18 GHz was extracted. During about three months' commissioning, some outstanding results have been achieved, such as 1.97 emA of O(6+), 1.7 emA of Ar(8+), 1.07 emA of Ar(9+), and 118 euA of Bi(28+). The source has also successfully delivered O(5+) and Ar(8+) ion beams for RFQ commissioning in April 2014. This paper will give a brief overview of the design of LECR4. Then, the latest results of this source at 18 GHz will be presented.

  8. The cooling of particle beams

    SciTech Connect

    Sessler, A.M.

    1994-10-01

    A review is given of the various methods which can be employed for cooling particle beams. These methods include radiation damping, stimulated radiation damping, ionization cooling, stochastic cooling, electron cooling, laser cooling, and laser cooling with beam coupling. Laser Cooling has provided beams of the lowest temperatures, namely 1 mK, but only for ions and only for the longitudinal temperature. Recent theoretical work has suggested how laser cooling, with the coupling of beam motion, can be used to reduce the ion beam temperature in all three directions. The majority of this paper is devoted to describing laser cooling and laser cooling with beam coupling.

  9. Do Type III-associated Escaping Electron Beams Cool The Corona?

    NASA Astrophysics Data System (ADS)

    Saint-Hilaire, Pascal; Wang, L.; Christe, S. D.; Vilmer, N.; Kerdraon, A.; Lin, R. P.

    2012-05-01

    A recent study of decimetric Type III radio burst emission from data from the Nancay Radio Heliograph (NRH) will be presented. It examined sizes, locations, and fluxes of close to 10'000 decimetric Type III bursts. The flux study suggests that electron beams related to Type III emission could be responsible for carrying energy away from the corona in a proportion similar to that of EUV nanoflare heating. This tentative conclusion was reached from comparing Type III dN/dS distributions to the dN/dS of EUV/SXR nano-/micro-flares. The biggest uncertainty is the radiative efficiency, i.e. the ratio of radiated energy in decimetric Type III bursts and the energy of the electrons in the beams associated with them. We will constrain this value through other, new observations: we have already computed the amount of Type III radiated energy from NRH observations, and we will now compare them with the amount of energy in the corresponding beam electron detected in-situ by the Wind spacecraft. Given our sample of close to 10'000 decimetric Type IIIs, we expect a decent amount of in-situ beam energy estimates from magnetically connected events. Moreover, we will compare with X-ray-derived energies from corresponding RHESSI (micro)flares, when such an association exists.

  10. "Do Type III-associated escaping electron beams cool the corona?"

    NASA Astrophysics Data System (ADS)

    Saint-Hilaire, P.; Wang, L.; Vilmer, N.; Kerdraon, A.

    2012-12-01

    A recent study of decimetric Type III radio burst emission from data from the Nancay Radio Heliograph will be presented. It examined sizes, locations, and fluxes of close to 10'000 decimetric Type III bursts. The flux study suggests that electron beams related to Type III emission could be responsible for carrying energy away from the corona in a proportion similar to EUV nanoflares. This tentative conclusion was reached from comparing Type III dN/dS distributions to the dN/dS of EUV/SXR nano-/micro-flares. The biggest uncertainty is the radiative efficiency, i.e. the ratio of radiated energy in decimetric Type III bursts and the energy of the electrons in the beams associated with them. We will constrain this value through other, new observations: we have already computed the amount of Type III radiated energy from NRH observations, and we will now compare them with the amount of energy in the corresponding beam electron detected in-situ by the Wind spacecraft. Given our sample of close to 10'000 decimetric Type IIIs, we expect a decent amount of in-situ beam energy estimates from magnetically connected events. Moreover, we will compare with X-ray-derived energies from corresponding RHESSI (micro)flares, when such an association exists.

  11. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  12. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  13. High frequency electromagnetic modes in a weakly magnetized relativistic electron plasma

    NASA Astrophysics Data System (ADS)

    Abbas, Gohar; Murtaza, G.; Kingham, R. J.

    2010-07-01

    Using the linearized Vlasov-Maxwell model, the polarization tensor for a weakly magnetized electron plasma is derived. For isotropic relativistic Maxwellian velocity distribution function, dispersion relations are obtained for both parallel and perpendicular propagations. The integrals (called Meijer G functions) that arise due to relativistic effects are examined in various limits and dispersion relations are derived for the nonrelativistic, weakly, strongly, and ultrarelativistic Maxwellian velocity distributions. It is generally observed that the propagation domains of the modes are enlarged as one proceeds from the nonrelativistic to the highly relativistic regime. Resultantly, due to the relativistic effects, the Whistler mode is suppressed in the R-wave, the nonpropagation band of X-mode is reduced, and the X-mode itself approaches the O-mode. Further, the results derived in the ultra- and nonrelativistic limits found to be in agreement with the earlier calculations [G. Abbas et al. Phys. Scr. 76, 649 (2007); F. F. Chen, Introduction to Plasma Physics and Controlled Fusion (Plenum, New York, 1984), Vol. 1].

  14. Enhancement of Natural Convection by Carbon Nanotube Films Covered Microchannel-Surface for Passive Electronic Cooling Devices.

    PubMed

    Zhang, Guang; Jiang, Shaohui; Yao, Wei; Liu, Changhong

    2016-11-16

    Owing to the outstanding properties of thermal conduction, lightweight, and chemical durability, carbon nanotubes (CNTs) have revealed promising applications in thermal management materials. Meanwhile, the increasingly popular portable electronics and the rapid development of space technology need lighter weight, smaller size, and more effective thermal management devices. Here, a novel kind of heat dissipation devices based on the superaligned CNT films and underlying microchannels is proposed, and the heat dissipation properties are measured at the natural condition. Distinctive from previous studies, by combining the advantages of microchannels and CNTs, such a novel heat dissipation device enables superior natural convection heat transfer properties. Our findings prove that the novel CNT-based devices could show an 86.6% larger total natural heat dissipation properties than bare copper plate. Further calculations of the radiation and natural convection heat transfer properties demonstrate that the excellent passive cooling properties of these CNT-based devices are primarily caused by the reinforcement of the natural convection heat transfer properties. Furthermore, the heat dissipation mechanisms are briefly discussed, and we propose that the very high heat transfer coefficients and the porous structures of superaligned CNT films play critical roles in reinforcing the natural convection. The novel CNT-based heat dissipation devices also have advantages of energy-saving, free-noise, and without additional accessories. So we believe that the CNT-based heat dissipation devices would replace the traditional metal-finned heat dissipation devices and have promising applications in electronic devices, such as photovoltaic devices, portable electronic devices, and electronic displays.

  15. Precise convective cooling simulation of electronic equipment under various g-conditions

    NASA Astrophysics Data System (ADS)

    Adam, Johannes; Stuempel, Dieter; Rath, Michael

    1991-12-01

    Using the thermohydraulic code 'THEBES' a three dimensional flow analysis of a Spacelab rack under forced convection and a combined convective, conductive and radiative analysis of a closed electronic box under various g conditions are presented. The capabilities and features of THEBES are described. The motivation to extend the thermal analysis cycle for better treatment of fluid flow and solid to air heat transfer is discussed. It is proposed to include THEBES in a thermal analysis toolsat and present a concept for integration of THEBES with ESABASE.

  16. Neutrino Signal of Electron-Capture Supernovae from Core Collapse to Cooling

    SciTech Connect

    Huedepohl, L.; Mueller, B.; Janka, H.-T.; Marek, A.; Raffelt, G. G.

    2010-06-25

    An 8.8M{sub {center_dot}}electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time ({approx}9 s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities ({approx}200 ms), luminosity equipartition among all species becomes almost perfect and the spectra of {nu}{sub e} and {nu}{sub {mu},{tau}}very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

  17. Measuring the electron electric dipole moment using laser-cooled cesium atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Zhu, Kunyan

    Semiconductor photocatalysis is a dynamic field at the forefront of environmental and energy research. This dissertation has focused on the development of novel nanomaterials to exceed performance for environmental and energy related applications in both liquid and gas phases as compared to traditional materials. This project investigated the impact of size of noble metal clusters on photocatalytic activity induced by UV and visible light. Compared to larger particles, sub-nanometer particles have shown much better activity for catalytic reactions in both liquid and gas phases. These nanoclusters supported on various semiconductors, such as TiO2 and CdS showed outstanding catalytic properties for oxidation of phenol in gas phase, removal of NO2 from gas phase via both oxidation and reduction routes and hydrogen production from water. The catalytic activities of sub-nanometer particles were much higher than those of known commercially available catalysts. Overall, this project has provided the first ever demonstration of the unique properties of ultra-small nanoparticles in sub-nanometer range for photocatalytic applications. Additionally, this project has focused on utilization of novel nanostructures to provide a high surface area support for photocatalysts and to achieve better dispersion of nanoparticles. More specifically, this research has focused on a new generation of highly ordered mesoporous SBA-15 sieves, which have large pore diameter (22 nm) and short pore length (500 nm), which were subsequently templated to facilitate photo-oxidation reactions. In addition, this project has focused on inverse opal structures to facilitate a better light capture inside these 3D structures, which can potentially lead to enhancement of photocatalytic reactions. All catalysts and catalysts' precursors were characterized using high resolution electron microscopy (HR-EM), which included Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Scanning

  18. Neutrino signal of electron-capture supernovae from core collapse to cooling.

    PubMed

    Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

    2010-06-25

    An 8.8M{⊙} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (∼9  s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (∼200  ms), luminosity equipartition among all species becomes almost perfect and the spectra of ν{e} and ν{μ,τ} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations.

  19. The recent and prospective developments of cooled IR FPAs for double application at Electron NRI

    NASA Astrophysics Data System (ADS)

    Arutunov, V. A.; Vasilyev, I. S.; Ivanov, V. G.; Prokofyev, A. E.

    2003-09-01

    The recent and prospective developments of monolithic silicon IR-Schottky-barrier staring focal plane arrays (IR SB FPAs), photodetector assembly, and digital thermal imaging cameras (TICs) at Electron National Research Institute (Electron NRI) are considered. Basic parameters for IR SB FPAs with 256x256 and 512x512 pixels, and TICs based on these arrays are presented. The problems emerged while proceeding from the developments of IR SB FPAs for the wavelength range from 3 μm to 5 μm to the developments of those ones for xLWIR range are indicated (an abrupt increase in the level of background architecture). Possibility for further improvement in basic parameters of IR SB FPAs are discussed (a decrease in threshold signal power down to 0.5-1.0"1013 W/element with an increase in quantum efficiency, a decrease in output noise and proceeding to Schottky barriers of degenerated semiconductor/silicon heterojunction, and implementation of these array parameters in photodetector assembly with improved thermal background shielding taking into consideration an optical structure of TIC for concrete application). It is concluded that relative simplicity of the technology and expected low cost of monolithic silicon IR SB FPAs with basic parameters compared with hybrid IR FPAs for the wavelength ranges from 3 μm to 5 μm and from 8 μm to 12 μm maintain large monolithic IR SB FPAs as a basis for developments of double application digital TICs in the Russian Federation.

  20. Cooling and Laser-Induced Fluorescence of Electronically-Excited He2 in a Supersonic Microcavity Plasma Jet

    NASA Astrophysics Data System (ADS)

    Su, Rui; Mironov, Andrey; Houlahan, Thomas, Jr.; Eden, J. Gary; LaboratoryOptical Physics; Engineering Team

    2016-09-01

    Laser-induced fluorescence (LIF) resulting from transitions between different electronic states of helium dimers generated within a microcavity plasma jet was studied with rotational resolution. In particular, the d3Σu+ , e3Πg and f3Σu+ states, all having electronic energies above 24 eV, are populated by a microplasma in 4 bar of helium gas and rotationally cooled through supersonic expansion. Analysis of two dimensional maps (spectrograms) of dimer emission spectra as a function of distance from the nozzle orifice indicates collisional coupling during the expansion between the lowest rotational levels of the e3Πg , f3Σu+ states and high rotational levels (around N=11) of the d3Σu+ state (all of which are in the v = 0 vibrational state). In an attempt to verify the coupling, a scanning dye laser (centered near 596 nm) pumps the b3Πg -> f3Σu+ transition of the molecule several hundred micrometers downstream of the nozzle. As a result, the emission intensities of relevant rotational lines are observed to be enhanced. This research shows the potential of utilizing microcavity plasma jets as a tool to study and manipulate the collisional dynamics of highly-excited diatomic molecules.

  1. Giant electromagnetic vortex and MeV monoenergetic electrons generated by short laser pulses in underdense plasma near quarter critical density region.

    PubMed

    Zhidkov, Alexei; Nemoto, Koshichi; Nayuki, Takuya; Oishi, Yuji; Fuji, Takashi

    2007-07-01

    Very efficient generation of monoenergetic, about 1MeV , electrons from underdense plasma with its electron density close to the critical, when irradiated by an intense femtosecond laser pulse, is found via two dimensional particle-in-cell simulation. The stimulated Raman scattering of a laser pulse with frequency omega< or =2omega(pl max) gives rise to a giant electromagnetic vortex. In contrast to electron acceleration by the well-known laser pulse wake, injected plasma electrons are accelerated up to vortex ponderomotive potential forming a quite monoenergetic distribution. A relatively high charge of such an electron source makes very efficient generation of soft gamma rays with homega>300 keV .

  2. Liquid nitrogen cooled integrated power electronics module with high current carrying capability and lower on resistance

    NASA Astrophysics Data System (ADS)

    Ye, Hua; Lee, Changwoo; Simon, Randy W.; Haldar, Pradeep; Hennessy, Michael J.; Mueller, Eduard K.

    2006-11-01

    This letter presents the development of high-performance integrated cryogenic power modules, where both driver components and power metal-oxide semiconductor field-effect transistors are integrated in a single package, to be used in a 50kW prototype cryogenic inverter operating at liquid nitrogen temperature. The authors have demonstrated a compact high-voltage, cryogenic integrated power module that exhibited more than 14 times improvement in on-resistance and continuous current carrying capability exceeding 40A. The modules are designed to operate at liquid nitrogen temperature with extreme thermal cycling. The power electronic modules are necessary components that provide control and switching for second generation, yttrium barium copper oxide-based high temperature superconductor devices including cables, motors, and generators.

  3. Cooling of Stored Beams

    SciTech Connect

    Mills, F.

    1986-06-10

    Beam cooling methods developed for the accumulation of antiprotons are being employed to assist in the performance of experiments in Nuclear and Particle Physics with ion beams stored in storage rings. The physics of beam cooling, and the ranges of utility of stochastic and electron cooling are discussed in this paper.

  4. A modified Bitter-type electromagnet and control system for cold atom experiments

    SciTech Connect

    Luan, Tian; Zhou, Tianwei; Chen, Xuzong; Ma, Zhaoyuan

    2014-02-15

    We present a modified Bitter-type electromagnet which features high magnetic field, fine electronic properties and efficient heat removal. The electromagnet is constructed from a stack of copper layers separated by mica layers that have the same shape. A distinctive design of cooling channels on the insulating layers and the parallel ducts between the layers ensures low resistance for cooling water to flow. A continuous current control system is also made to regulate the current through the electromagnet. In our experiment, versatile electromagnets are applied to generate magnetic field and gradient field. From our measurements, a peak magnetic field of 1000 G and a peak gradient field of 80 G/cm are generated in the center of the apparatuses which are 7 cm and 5 cm away from the edge of each electromagnet with a current of 230 A and 120 A, respectively. With the effective feedback design in the current control system and cooling water flow of 3.8 l/min, the stability of the current through the electromagnets can reach 10{sup −5}.

  5. A modified Bitter-type electromagnet and control system for cold atom experiments.

    PubMed

    Luan, Tian; Zhou, Tianwei; Chen, Xuzong; Ma, Zhaoyuan

    2014-02-01

    We present a modified Bitter-type electromagnet which features high magnetic field, fine electronic properties and efficient heat removal. The electromagnet is constructed from a stack of copper layers separated by mica layers that have the same shape. A distinctive design of cooling channels on the insulating layers and the parallel ducts between the layers ensures low resistance for cooling water to flow. A continuous current control system is also made to regulate the current through the electromagnet. In our experiment, versatile electromagnets are applied to generate magnetic field and gradient field. From our measurements, a peak magnetic field of 1000 G and a peak gradient field of 80 G/cm are generated in the center of the apparatuses which are 7 cm and 5 cm away from the edge of each electromagnet with a current of 230 A and 120 A, respectively. With the effective feedback design in the current control system and cooling water flow of 3.8 l/min, the stability of the current through the electromagnets can reach 10(-5).

  6. Linear and nonlinear coupling of electromagnetic and electrostatic fluctuations with one dimensional trapping of electrons using product bi (r,q) distribution

    NASA Astrophysics Data System (ADS)

    Aziz, Tahir; Masood, W.; Qureshi, M. N. S.; Shah, H. A.; Yoon, P. H.

    2016-06-01

    In the present paper, we have investigated the ramifications of adiabatic trapping of electrons using a bi product ( r , q ) distribution function on obliquely propagating Alfven waves in a low β plasma. In this regard, we have analyzed the linear and nonlinear dispersion characteristics of finite amplitude coupled kinetic Alfven-acoustic solitary waves using the two-potential theory and employing Sagdeev potential approach. We have deliberated upon the results of the present inquest and highlighted its importance by citing works that have reported the simultaneous presence of electromagnetic pulses and flat-topped distribution of electrons.

  7. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons.

    PubMed

    Smith, Ray T; Jjunju, Fred P M; Young, Iain S; Taylor, Stephen; Maher, Simon

    2016-07-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting's theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.

  8. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons

    NASA Astrophysics Data System (ADS)

    Smith, Ray T.; Jjunju, Fred P. M.; Young, Iain S.; Taylor, Stephen; Maher, Simon

    2016-07-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting's theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.

  9. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons

    PubMed Central

    Smith, Ray T.; Jjunju, Fred P. M.; Young, Iain S.; Taylor, Stephen

    2016-01-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting’s theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond. PMID:27493580

  10. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1994-02-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 185 citations and includes a subject term index and title list.)

  11. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 204 citations and includes a subject term index and title list.)

  12. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-04-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications for high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion are examined. (Contains a minimum of 151 citations and includes a subject term index and title list.)

  13. Cooling in a compound bucket

    SciTech Connect

    Shemyakin, A.; Bhat, C.; Broemmelsiek, D.; Burov, A.; Hu, M.; /Fermilab

    2007-09-01

    Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results.

  14. Noise Temperature and IF Bandwidth of a 530 GHz Heterodyne Receiver Employing a Diffusion-Cooled Superconducting Hot-Electron Mixer

    NASA Technical Reports Server (NTRS)

    Skalare, A.; McGrath, W. R.; Bumble, B.; LeDuc, H. G.; Burke, P. J.; Verheijen, A. A.; Prober, D. E.

    1995-01-01

    We report on the first heterodyne measurements with a diffusion-cooled hot-electron bolometer mixer in the submillimeter wave band, using a waveguide mixer cooled to 2.2 K. The best receiver noise temperature at a local oscillator frequency of 533 GHz and an intermediate frequency of 1.4 GHz was 650 K (double sideband). The 3 dB IF roll-off frequency was around 1.7 to 1.9 GHz, with a weak dependence on the device bias conditions.

  15. Experimental investigation of dissociation pathways of cooled HeH{sup +} following valence electron excitation at 32 nm by intense free-electron-laser radiation

    SciTech Connect

    Pedersen, H. B.; Lammich, L.; Domesle, C.; Jordon-Thaden, B.; Ullrich, J.; Wolf, A.; Heber, O.; Treusch, R.; Guerassimova, N.

    2010-08-15

    The dissociation pathways of HeH{sup +} have been investigated below the first ionization continuum by photoabsorption at 32 nm, using fragment momentum imaging in a crossed-beams experiment at the free-electron laser in Hamburg (FLASH). Investigations were done both for ions with several vibrational levels excited in the ion source and for ions vibrationally cooled in an electrostatic ion trap prior to the irradiation. The product channels He{sup +}(1s)+H(nl) and He(1snl)+H{sup +} were separated and the He(1snl)+H{sup +} channel was particularly studied by coincidence detection of the He and H{sup +} fragments on two separate fragment detectors. At 32 nm excitation, the branching ratio between the product channels was found to be {sigma}{sub He}{sup +}{sub +H}/{sigma}{sub He+H}{sup +}=0.96{+-}0.11 for vibrationally hot and 1.70{+-}0.48 for vibrationally cold ions. The spectra of kinetic energy releases for both channels revealed that photodissociation at 32 nm leads to high Rydberg states (n > or approx. 3-4) of the emerging atomic fragments irrespective of the initial vibrational excitation of HeH{sup +}. The fragment angular distributions showed that dissociation into the He+H{sup +} channel mostly ({approx}70%) proceeds through {sup 1{Pi}} states, while for the He{sup +}+H channel {sup 1{Sigma}} and {sup 1{Pi}} states are of about equal importance.

  16. Experimental investigation of the ionospheric hysteresis effect on the threshold excitation level of the Stimulated Electromagnetic Emission (SEE) during heating at the second electron gyro-harmonic frequency

    NASA Astrophysics Data System (ADS)

    Samimi, A.; Scales, W.; Cruz, M.; Isham, B.; Bernhardt, P. A.

    2012-12-01

    Recent experimental observations of the stimulated electromagnetic emission (SEE) spectrum during heating at the second electron gyro-harmonic show structures ordered by ion gyro-frequency. The proposed generation mechanism considers parametric decay of a pump upper hybrid/electron Bernstein (UH/EB) wave into another UH/EB and a group of neutralized ion Bernstein waves. The presumption of the proposed mechanism is that the pump electromagnetic wave is converted into the UH/EB wave. This conversion process generates field aligned irregularity which exhibits hysteresis effect. The predicted ionospheric hysteresis effect is studied during the PARS 2012 at HAARP. The preliminary results are presented for the first time. Also, experimental study of the effects of 1) the transmitter beam angle and 2) the transmitter frequency offset relative to the second electron gyro-harmonic frequency on the ion gyro-harmonic structures in the SEE spectrum are provided. The aforementioned observations are compared to the predictions of the analytical model. Possible connection of the SEE spectral features and artificially generated ionospheric descending layer is also discussed

  17. Refrigerant directly cooled capacitors

    DOEpatents

    Hsu, John S.; Seiber, Larry E.; Marlino, Laura D.; Ayers, Curtis W.

    2007-09-11

    The invention is a direct contact refrigerant cooling system using a refrigerant floating loop having a refrigerant and refrigeration devices. The cooling system has at least one hermetic container disposed in the refrigerant floating loop. The hermetic container has at least one electronic component selected from the group consisting of capacitors, power electronic switches and gating signal module. The refrigerant is in direct contact with the electronic component.

  18. Stimulated electromagnetic emission and plasma line during pump wave frequency stepping near 4th electron gyroharmonic at HAARP

    NASA Astrophysics Data System (ADS)

    Grach, Savely; Sergeev, Evgeny; Shindin, Alexey; Mishin, Evgeny; Watkins, Brenton

    Concurrent observations of stimulated (secondary) electromagnetic emissions (SEE) and incoherent plasma line (PL) backscatter from the MUIR radar during HF pumping of the ionosphere by the HAARP heating facility (62.4(°) °N, 145.15(°) W, magnetic inclination α = 75.8^circ) with the pump wave (PW) frequency sweeps about the fourth electron gyroharmonic (4f_c) are presented. The PW frequency f0 was changed every 0.2 s in a 1-kHz step, i.e. with the rate of r_{f_0}=5 kHz/s. PW was transmitted at the magnetic zenith (MZ). Prior to sweeping, PW was transmitted continuously (CW) during 2 min at f_0 = 5730 kHz <4f_c to create the “preconditioned” ionosphere with small-scale magnetic field-aligned irregularities. During CW pumping, a typical SEE spectrum for f_0<4f_c, containing the prominent downshifted maxiμm (DM) shifted by Delta f_{DM} = f_{DM}-f_0approx-9 kHz, developed in 5-10 s after PW turn on. The PL echoes were observed during 2-3 s from the range dsim 220 km corresponding to the altitude slightly above PW reflection height. After sim5 s the PL echoes descended to dsim 210-212 km corresponding to the height h = d / (sinalpha) by sim 7 km below the height where f_0 = 4f_c. During frequency sweeps, two upshifted features appeared in the SEE spectrum for f_0> 4f_c, namely BUM_S and BUM_D. The former (stationary broad upshifted maxiμm) peaks at Delta f_{BUMs} approx f0 - nfc (d) + 15-20 kHz and is a typical SEE spectral feature. The latter, the dynamic BUM_D at smaller Delta f, is observed only at high pump powers (ERP=1.7 GW) and corresponds to artificial descending plasma layers created in the F-region ionosphere [1]. In the experiment in question, the BUM_D was present for f_0> f^*, where f^* was 5805-5815 kHz during stepping up and sim 10 kHz less for stepping down, and located 8-10 km below the background F-layer. The miniμm DM which indicated that f_0=4f_c=f_{uh} in the background ionospheric plasma, was sim 5760 kHz. The PL was observed only for f_0

  19. Computer Simulation of Interactions between High-Power Electromagnetic Fields and Electronic Systems in a Complex Environment.

    DTIC Science & Technology

    1997-05-01

    and immune to interior resonance corruption. This work lays a foundation for the development of a very useful and powerful technique, which...show that the resulting solution has a good efficiency and accuracy and is completely immune to the problem of interior resonance . The technical...electromagnetic modeling for high-frequency MRI applications," International Society for Magnetic Resonance in Medicine Fifth Scientific Meeting, Vancouver, Canada

  20. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Relativistic kinematics of the electromagnetic fields of a guided mode

    NASA Astrophysics Data System (ADS)

    Rivlin, Lev A.

    2000-02-01

    It is shown that during the observation of a wave in a waveguide from a comoving reference system travelling at a velocity equal to the group velocity of the wave, the wave propagation is halted and the electromagnetic energy contained in the waveguide proves to be stationary. The nonzero rest mass of the photons in the waveguide is equivalent to this rest energy and is identical with the rest mass measured in dynamic experiments.

  1. Investigating the electron density of multi-MeV X-ray-induced air plasmas at low pressures based on electromagnetic resonant cavity analysis

    NASA Astrophysics Data System (ADS)

    Ribière, M.; d'Almeida, T.; Cessenat, O.; Maulois, M.; Pouzalgues, R.; Crabos, B.; Delbos, C.; Garrigues, A.; Azaïs, B.

    2016-12-01

    We investigate air plasmas generated by multi-MeV pulsed X-rays at pressures ranging from 10-5 to 10-1 mbar. The experimental approach used for these studies is based on measurements of resonant frequencies damping and shift for different electromagnetic modes within a cylindrical cavity. Time-integrated electron densities in X-ray-induced air plasmas are inferred from the damping rate of the measured magnetic fields and their corresponding frequency shifts. In the present study, electron densities ranging from 108 to 109 cm-3 at pressures ranging from 10-3 to 10-1 mbar have been measured. Experimental results were confronted to 3D Maxwell-Vlasov Particle-In-Cell simulations incorporating a radiation-induced electric conductivity model. The method used in this work enables determining microscopic and macroscopic physical quantities within low pressure air plasmas generated by pulsed X-ray.

  2. Formation of very hard electron and gamma-ray spectra of flat-spectrum radio quasars in the fast-cooling regime

    NASA Astrophysics Data System (ADS)

    Yan, Dahai; Zhang, Li; Zhang, Shuang-Nan

    2016-07-01

    In the external Compton scenario, we investigate the formation of a very hard electron spectrum in the fast-cooling regime, using a time-dependent emission model. It is shown that a very hard electron distribution, N^' }_e({γ ^' })∝ {γ ^' }^{-p}, with spectral index p ˜ 1.3 is formed below the minimum energy of injection electrons when inverse Compton scattering takes place in the Klein-Nishina regime, i.e. inverse Compton scattering of relativistic electrons on broad-line region radiation in flat-spectrum radio quasars. This produces a very hard gamma-ray spectrum and can explain in reasonable fashion the very hard Fermi-Large Area Telescope (LAT) spectrum of the flat-spectrum radio quasar 3C 279 during the extreme gamma-ray flare in 2013 December.

  3. Electromagnetic fields of a relativistic electron avalanche with special attention to the origin of lightning signatures known as narrow bipolar pulses

    NASA Astrophysics Data System (ADS)

    Cooray, Vernon; Cooray, Gerald; Marshall, Thomas; Arabshahi, Shahab; Dwyer, Joseph; Rassoul, Hamid

    2014-11-01

    In the present study, electromagnetic fields of accelerating charges were utilized to evaluate the electromagnetic fields generated by a relativistic electron avalanche. In the analysis it is assumed that all the electrons in the avalanche are moving with the same speed. In other words, the growth or the decay of the number of electrons takes place only at the head of the avalanche. It is shown that the radiation is emanating only from the head of the avalanche where electrons are being accelerated. It is also shown that an analytical expression for the radiation field of the avalanche at any distance can be written directly in terms of the e-folding length of the avalanche. This model of the avalanche was utilized to test the idea whether the source of the lightning signatures known as narrow bipolar pulses could be relativistic avalanches. The idea was tested by using the simultaneously measured electric fields of narrow bipolar pulses at two distances, one measured far away from the source and the other in the near vicinity. The avalanche parameters were extracted from the distant field and they are used to evaluate the close field. The results show that the source of the NBP can be modeled either as a single or a multiple burst of relativistic avalanches with speed of avalanches in the range of 2-3 × 108 m/s. The multiple avalanche model agrees better with the experimental data in that it can also generate the correct signature of the time derivatives and the HF and VHF radiation bursts of NBP.

  4. Ab initio study on the electronic states and laser cooling of AlCl and AlBr

    NASA Astrophysics Data System (ADS)

    Rong, Yang; Bin, Tang; Tao, Gao

    2016-04-01

    We investigate whether AlCl and AlBr are promising candidates for laser cooling. We report new ab initio calculations on the ground state X1Σ+ and two low-lying states (A1Π and a3Π) of AlCl and AlBr. The calculated spectroscopic constants show good agreement with available theoretical and experimental results. We also obtain the permanent dipole moments (PDMs) curve at multi-reference configuration interaction (MRCI) level of theory. The transition properties of A1Π and a3Π states are predicted, including the transition dipole moments (TDMs), Franck-Condon factors (FCFs), radiative times and radiative width. The calculated radiative lifetimes are of the order of a nanosecond, implying that they are sufficiently short for rapid laser cooling. Both AlCl and AlBr have highly diagonally distributed FCFs which are crucial requirement for molecular laser cooling. The results demonstrate the feasibility of laser cooling AlCl and AlBr, and we propose laser cooling schemes for AlCl and AlBr.

  5. Cooling of a multichip electronic module by means of confined two-dimensional jets of dielectric liquid

    NASA Astrophysics Data System (ADS)

    Wadsworth, D. C.; Mudawar, I.

    1990-11-01

    Experiments were performed to investigate single-phase heat transfer from a smooth 12.7 x 12.7-sq-mm simulated chip to a two-dimensional jet of dielectric FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confinement channel height, and impingement velocity have been examined. Channel height had a negligible effect on the heat-transfer performance of the jet. A correlation for the convective heat-transfer coefficient is presented as a function of jet width, heater length, flow velocity, and fluid properties. A self-contained multichip cooling module consisting of a 3 x 3 array of heat sources confirmed the uniformity and predictability of cooling for each of the nine chips, and proved the cooling module is well suited for packaging large arrays of high-power-density chips.

  6. Cooling of a multichip electronic module by means of confined two-dimensional jets of dielectric liquid

    SciTech Connect

    Wadsworth, D.C.; Mudawar, I. )

    1990-11-01

    Experiments were performed to investigate single-phase heat transfer froma smooth 12.7 {times} 12.7 mm{sup 2} simulated chip to a two-dimensional jet of dielectric Fluorinert FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confined channel height, and impingement velocity have been examined. Channel height had a negligible effect ont eh theat transfer performance of the jet for the conditions of the present study. A correlation for the convective heat transfer coefficient is presented as a function of jet, width, heat length, flow velocity, and fluid properties. A self-contained multichip cooling module consisting of a 3 {times} 3 array of heat sources confirmed the uniformity and predictability of cooling for each of the nine chips, and proved the cooling module is well suited for packaging large arrays of high-power density chips.

  7. Radiative power and electron cooling rates for oxygen in steady-state and transient plasmas at densities beyond the coronal limit

    SciTech Connect

    Keane, C.; Skinner, C.H.

    1986-01-01

    We have developed a time-dependent, collisional-radiative model to calculate radiative power and electron cooling rates for oxygen at intermediate densities (10/sup 16/ cm/sup -3/ less than or equal to n/sub e/ less than or equal to 10/sup 20/ cm/sup -3/) where the usual coronal approximation is not valid. Large differences from coronal values are predicted. The behavior of the steady-state radiative power loss coefficient, L/sub Z, is investigated as the electron density is increased. Generalized power loss coefficients applicable to transient plasmas are derived and applied to ionizing and recombining oxygen plasmas. Time-dependent effects are found to play a large role both in terms of the total radiated power and the net electron energy loss rate. 41 refs., 11 figs.

  8. Assessment of Electromagnetic Interference with Active Cardiovascular Implantable Electronic Devices (CIEDs) Caused by the Qi A13 Design Wireless Charging Board

    PubMed Central

    Seckler, Tobias; Jagielski, Kai; Stunder, Dominik

    2015-01-01

    Electromagnetic interference is a concern for people wearing cardiovascular implantable electronic devices (CIEDs). The aim of this study was to assess the electromagnetic compatibility between CIEDs and the magnetic field of a common wireless charging technology. To do so the voltage induced in CIEDs by Qi A13 design magnetic fields were measured and compared with the performance limits set by ISO 14117. In order to carry this out a measuring circuit was developed which can be connected with unipolar or bipolar pacemaker leads. The measuring system was positioned at the four most common implantation sites in a torso phantom filled with physiological saline solution. The phantom was exposed by using Helmholtz coils from 5 µT to 27 µT with 111 kHz sine-bursts or by using a Qi A13 design wireless charging board (Qi-A13-Board) in two operating modes “power transfer” and “pinging”. With the Helmholtz coils the lowest magnetic flux density at which the performance limit was exceeded is 11 µT. With the Qi-A13-Board in power transfer mode 10.8% and in pinging mode 45.7% (2.2% at 10 cm distance) of the performance limit were reached at maximum. In neither of the scrutinized cases, did the voltage induced by the Qi-A13-Board exceed the performance limits. PMID:26024360

  9. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  10. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  11. Physical principles of the amplification of electromagnetic radiation due to negative electron masses in a semiconductor superlattice

    NASA Astrophysics Data System (ADS)

    Shorokhov, A. V.; Pyataev, M. A.; Khvastunov, N. N.; Hyart, T.; Kusmartsev, F. V.; Alekseev, K. N.

    2015-02-01

    In a superlattice placed in crossed static electric and magnetic fields, under certain conditions, the inversion of electron population can appear at which the average energy of electrons is above the middle of the mini-band and the effective mass of the electron is negative. This is the implementation of the negative effective mass amplifier and generator (NEMAG) in the superlattice. It can result in the amplification and generation of terahertz radiation even in the absence of negative differential conductivity.

  12. Analysis of the dependence of surfatron acceleration of electrons by an electromagnetic wave in space plasma on the particle momentum along the wave front

    SciTech Connect

    Erokhin, A. N.; Zol’nikova, N. N.; Erokhin, N. S.

    2016-01-15

    Based on the numerical solution of the nonlinear nonstationary second-order equation for the wave phase on the particle trajectory, the dynamics of surfatron acceleration of electrons by an electromagnetic wave propagating across the external magnetic field in space plasma is analyzed as a function of the electron momentum along the wave front. Numerical calculations show that, for strongly relativistic initial values of the electron momentum component along the wave front g{sub y}(0) (the other parameters of the problem being the same), electrons are trapped into the regime of ultrarelativistic surfatron acceleration within a certain interval of the initial wave phase Ψ(0) on the particle trajectory. It is assumed in the calculations that vertical bar Ψ(0) vertical bar ≤ π. For strongly relativistic values of g{sub y}(0), electrons are immediately trapped by the wave for 19% of the initial values of the phase Ψ(0) (favorable phases). For the rest of the values of Ψ(0), trapping does not occur even at long times. This circumstance substantially simplifies estimations of the wave damping due to particle acceleration in subsequent calculations. The dynamics of the relativistic factor and the components of the electron velocity and momentum under surfatron acceleration is also analyzed. The obtained results are of interest for the development of modern concepts of possible mechanisms of generation of ultrarelativistic particle fluxes in relatively calm space plasma, as well as for correct interpretation of observational data on the fluxes of such particles and explanation of possible reasons for the deviation of ultrarelativistic particle spectra detected in the heliosphere from the standard power-law scalings and the relation of these variations to space weather and large-scale atmospheric processes similar to tropical cyclones.

  13. Stochastic Cooling

    SciTech Connect

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  14. Electron impact cross-sections and cooling rates for methane. [in thermal balance of electrons in atmospheres and ionospheres of planets and satellites in outer solar system

    NASA Technical Reports Server (NTRS)

    Gan, L.; Cravens, T. E.

    1992-01-01

    Energy transfer between electrons and methane gas by collisional processes plays an important role in the thermal balance of electrons in the atmospheres and ionospheres of planets and satellites in the outer solar system. The literature is reviewed for electron impact cross-sections for methane in this paper. Energy transfer rates are calculated for elastic and inelastic processes using a Maxwellian electron distribution. Vibrational, rotational, and electronic excitation and ionization are included. Results are presented for a wide range of electron temperatures and neutral temperatures.

  15. Modeling of Electromagnetic Heating in RF Copper Accelerating Cavities

    SciTech Connect

    Awida, M. H.; Gonin, I.; Romanov, Romanov; Khabiboulline, T.; Yakovlev, V.

    2016-01-17

    Electromagnetic heating is a critical issue in normal conducting copper RF cavities that are employed in particle accelerators. With several tens to hundreds of kilowatts dissipated RF power, there must be an effective cooling scheme whether it is water or air based or even a combination of both. In this paper we investigate the electromagnetic heating in multiple cavities that were designed at Fermilab exploring how the electromagnetic and thermal analyses are coupled together to properly design the cooling of such cavities.

  16. Extensive theoretical study on electronically excited states of calcium monochloride: Molecular laser cooling and production of ultracold chlorine atoms

    NASA Astrophysics Data System (ADS)

    Fu, Mingkai; Ma, Haitao; Cao, Jianwei; Bian, Wensheng

    2016-05-01

    Nine doublet Λ-S states of calcium monochloride (CaCl) are calculated using the internally contracted multireference configuration interaction method with the Davidson correction. Both the core subvalence and spin-orbit coupling effects are taken into account. Laser cooling of CaCl and production of ultracold chlorine atoms are investigated and assessed. Our computed spectroscopic constants and radiative lifetimes match the available experimental data very well. The determined Franck-Condon factors and vibrational branching ratios of the A 2 Π 1 / 2 ( ν ' ) ← X 2 Σ1 / 2 + ( ν ) transition are highly diagonally distributed and the evaluated radiative lifetime for the A2Π1/2(ν' = 0) state is 28.2 ns, which is short enough for rapid laser cooling. Subsequently, detection of cold molecules via resonance enhanced multiphoton ionization to determine the final quantum state populations is discussed and the ionization energy calculated. A multi-pulse excitation scheme is proposed for producing ultracold chlorine atoms from zero-energy photodissociation of the cooled CaCl. Our results demonstrate the possibility of producing ultracold CaCl molecules and Cl atoms.

  17. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  18. Conduction cooling: multicrate fastbus hardware

    SciTech Connect

    Makowiecki, D.; Sims, W.; Larsen, R.

    1980-11-01

    Described is a new and novel approach for cooling nuclear instrumentation modules via heat conduction. The simplicity of liquid cooled crates and ease of thermal management with conduction cooled modules are described. While this system was developed primarily for the higher power levels expected with Fastbus electronics, it has many general applications.

  19. Information Security due to Electromagnetic Environments

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Hidenori; Seto, Shinji

    Generally, active electronic devices emit slightly unintentional electromagnetic noise. From long ago, electromagnetic emission levels have been regulated from the aspect of electromagnetic compatibility (EMC). Also, it has been known the electromagnetic emissions have been generated from the ON/OFF of signals in the device. Recently, it becomes a topic of conversation on the information security that the ON/OFF on a desired signal in the device can be reproduced or guessed by receiving the electromagnetic emission. For an example, a display image on a personal computer (PC) can be reconstructed by receiving and analyzing the electromagnetic emission. In sum, this fact makes known information leakage due to electromagnetic emission. “TEMPEST" that has been known as a code name originated in the U. S. Department of Defense is to prevent the information leakage caused by electromagnetic emissions. This paper reports the brief summary of the information security due to electromagnetic emissions from information technology equipments.

  20. Self-consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2. Wave Induced Ring Current Precipitation and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.; Liemohn, M. W.

    2007-01-01

    This paper continues presentation and discussion of the results from our new global self-consistent theoretical model of interacting ring current ions and propagating electromagnetic ion cyclotron waves [Khazanov et al., 2006]. To study the effects of electromagnetic ion cyclotron wave propagation and refraction on the wave induced ring current precipitation and heating of the thermal plasmaspheric electrons, we simulate the May 1998 storm. The main findings after a simulation can be summarized as follows. Firstly, the wave induced ring current precipitation exhibits quite a lot of fine structure, and is highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 x 10(exp 6) (cm(raised dot) s(raised dot) sr(raised dot) (sup -1)) are observed during the maill and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not connected to the most intense waves in simple manner. The characteristics of the wave power spectral density distribution over the wave normal angle are extremely crucial for the effectiveness of the ring current ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from RAM [Kozyra et al., 1997a] reveals that although we observe a qualitative agreement between the localizations of the wave induced precipitations in the models, there is no quantitative agreement between the magnitudes of the fluxes. The quantitative differences are mainly due to a qualitative difference between the characteristics of the wave power spectral density distributions over the wave normal angle in RAM and in our model. Thirdly, the heat fluxes to plasmaspheric electrons caused by Landau resonate energy absorption from electromagnetic ion cyclotron waves are observed in the postnoon-premidnight MLT sector, and can reach the magnitude of 10(exp 11) eV/(cm(sup 2)(raised dot)s). The Coulomb

  1. Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio.

    PubMed

    Hori, Masaki; Aghai-Khozani, Hossein; Sótér, Anna; Barna, Daniel; Dax, Andreas; Hayano, Ryugo; Kobayashi, Takumi; Murakami, Yohei; Todoroki, Koichi; Yamada, Hiroyuki; Horváth, Dezső; Venturelli, Luca

    2016-11-04

    Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio [Formula: see text] can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10(-9) to 16 × 10(-9) About 2 × 10(9) antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, [Formula: see text] was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10(-10).

  2. Parametric Excitation of Very Low Frequency (VLF) Electromagnetic Whistler Waves and Interaction with Energetic Electrons in Radiation Belt

    NASA Astrophysics Data System (ADS)

    Sotnikov, V.; Kim, T.; Caplinger, J.; Main, D.; Mishin, E.; Gershenzon, N.; Genoni, T.; Paraschiv, I.; Rose, D.

    2016-09-01

    The concept of a parametric antenna in ionospheric plasma is analyzed. Such antennas are capable of exciting electromagnetic radiation fields, specifically the creation of whistler waves generated at the very low frequency (VLF) range, which are also capable of propagating large distances away from the source region. The mechanism of whistler wave generation is considered a parametric interaction of quasi-electrostatic low oblique resonance (LOR) oscillations excited by 1conventional loop antenna. The transformation of LOR waves on quasi-neutral density perturbations in the near field of an antenna gives rise to whistler waves on combination frequencies. It is shown in this work that the amplitude of these waves can considerably exceed the amplitude of whistler waves directly excited by a loop. Additionally, particle-in-cell (PIC) simulations, which demonstrate the excitation and spatial structure of VLF waves excited by a loop antenna, is presented. Possible applications including the wave-particle interactions to mitigate performance anomalies of Low Earth Orbit (LEO) satellites, active space experiments, communication via VLF waves, and modification experiments in the ionosphere will be discussed.

  3. Joint Services Electronics Program.

    DTIC Science & Technology

    1987-12-31

    neceeemar and Identify by black number) INFORMATION ELECTRONICS QUANTUM ELECTRONICS SOLID STATE ELECTRONICS ELECTROMAGNETICS 20. ABSTRACT (Continue an...Electromagnetics, two in Quantum Electronics, and two in Information Electrn, i DD N 1473 EDITION OF I NOV OS IS OBSOLETED J, A"" UNCLASSIFIED...units in Solid State Electronics, two in Electromagnetics, two in Quantum Electronics, and two in Information Electronics. The Solid State Electronics

  4. Nuclear Electromagnetic Pulse Review

    NASA Astrophysics Data System (ADS)

    Dinallo, Michael

    2011-04-01

    Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets - fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

  5. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  6. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  7. Electromagnetic shocks on the optical cycle of ultrashort pulses in triple-resonance Lorentz dielectric media with subfemtosecond nonlinear electronic Debye relaxation.

    PubMed

    Gilles, L; Moloney, J V; Vázquez, L

    1999-07-01

    The dynamical evolution of an intense ultrashort sub-10-fs two-cycle optical pulse is considered as it propagates through a transparent third-order dielectric medium characterized by three resonance lines and a finite sub-fs relaxation time of the electronic nonlinearity. Numerical integration of the full Maxwell's equations incorporating triple-resonance Lorentz linear dispersion and Debye nonlinear dispersion, for a linearly polarized electromagnetic pulse centered at lambda(0)=1.24 microm in the normal dispersion region near the zero dispersion wavelength, shows the formation of shocks occurring on the optical cycle due to the generation of optical harmonics. The finite relaxation time of the nonlinear electronic response (sub-fs time scale) (i) slows down the steepening rate of the optical cycle; (ii) does not limit the generation of strongly phase matched optical harmonics, and consequently the development of infinitely sharp edges on the optical cycle producing its breaking when linear dispersion is not included; (iii) reduces the production of phase matched harmonics and consequently the sharpening of the jumps when dispersion is present, compared to the case of an instantaneous nonlinear response; and (iv) reduces the harmonic spectrum spreading and modulation at later times on the appearance of self-steepening of the electric field envelope.

  8. Laser cooling and trapping of atomic particles. January 1970-September 1989 (Citations from the NTIS data base). Report for Jan 70-Sep 89

    SciTech Connect

    Not Available

    1989-11-01

    This bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps with very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications include high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains 97 citations fully indexed and including a title list.)

  9. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  10. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  11. Stochastic cooling at Fermilab

    SciTech Connect

    Marriner, J.

    1986-08-01

    The topics discussed are the stochastic cooling systems in use at Fermilab and some of the techniques that have been employed to meet the particular requirements of the anti-proton source. Stochastic cooling at Fermilab became of paramount importance about 5 years ago when the anti-proton source group at Fermilab abandoned the electron cooling ring in favor of a high flux anti-proton source which relied solely on stochastic cooling to achieve the phase space densities necessary for colliding proton and anti-proton beams. The Fermilab systems have constituted a substantial advance in the techniques of cooling including: large pickup arrays operating at microwave frequencies, extensive use of cryogenic techniques to reduce thermal noise, super-conducting notch filters, and the development of tools for controlling and for accurately phasing the system.

  12. Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

    NASA Technical Reports Server (NTRS)

    Hartmann, S. R.; Happer, W.

    1974-01-01

    The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

  13. Sorption cooling: a valid extension to passive cooling

    NASA Astrophysics Data System (ADS)

    Doornink, Jan; Burger, Johannes; ter Brake, Marcel

    2007-10-01

    Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into limitations that prohibit accommodation on a spacecraft. The approach to this issue has been to find a technology able to supplement passive cooling for lower temperatures, which maintains as much as possible of the advantages of passive coolers. Sorption cooling employs a closed cycle Joule-Thomson expansion process to achieve the cooling effect. Sorption cells perform the compression phase in this cycle. At a low temperature and pressure, these cells adsorb the working fluid. At a higher temperature they desorb the fluid and thus produce a high-pressure flow to the restriction in the cold stage. The sorption process selected for this application is of the physical type, which is completely reversible. It does not suffer from degradation as is the case with chemical sorption of e.g. hydrogen in metal hydrides. Sorption coolers include no moving parts except for some check valves, they export neither mechanical vibrations nor electromagnetic interference, and are potentially very dependable due to their simplicity. The required cooling temperature determines the type of working fluid to be applied. Sorption coolers can be used in conjunction with passive cooling for heat rejection at different levels. This paper starts with a brief discussion on applications of passive coolers in different types of orbits and the limitations on passive cooling at low cooling temperatures. Next, the working principle of sorption cooling is summarized. The DARWIN mission is chosen as an example application of sorption and passive cooling and special attention is paid to the

  14. Sorption cooling: A valid extension to passive cooling

    NASA Astrophysics Data System (ADS)

    Doornink, D. J.; Burger, J. F.; ter Brake, H. J. M.

    2008-05-01

    Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into limitations that prohibit accommodation on a spacecraft. The approach to this issue has been to find a technology able to supplement passive cooling for lower temperatures, which maintains as much as possible of the advantages of passive coolers. Sorption cooling employs a closed cycle Joule-Thomson expansion process to achieve the cooling effect. Sorption cells perform the compression phase in this cycle. At a low temperature and pressure, these cells adsorb the working fluid. At a higher temperature they desorb the fluid and thus produce a high-pressure flow to the expander in the cold stage. The sorption process selected for this application is of the physical type, which is completely reversible. It does not suffer from degradation as is the case with chemical sorption of, e.g., hydrogen in metal hydrides. Sorption coolers include no moving parts except for some check valves, they export neither mechanical vibrations nor electromagnetic interference, and are potentially very dependable due to their simplicity. The required cooling temperature determines the type of working fluid to be applied. Sorption coolers can be used in conjunction with passive cooling for heat rejection at different levels. This paper starts with a brief discussion on applications of passive coolers in different types of orbits and on the limitations of passive cooling for lower cooling temperatures. Next, the working principle of sorption cooling is summarized. The DARWIN mission is chosen as an example application of sorption and passive cooling and special attention is paid to the

  15. Heavy atom nitroxyl radicals. VI. The electronic spectrum of jet-cooled H2PO, the prototypical phosphoryl free radical

    NASA Astrophysics Data System (ADS)

    Gharaibeh, Mohammed A.; Clouthier, Dennis J.; Tarroni, Riccardo

    2011-12-01

    The previously unknown electronic spectrum of the H2PO free radical has been identified in the 407-337 nm region using a combination of laser-induced fluorescence and single vibronic level emission spectroscopy. High level ab initio predictions of the properties of the ground and first two excited doublet states were used to identify the spectral region in which to search for the electronic transition and were used to aid in the analysis of the data. The band system is assigned as the {tilde B}2A'-{tilde X}2A' electronic transition which involves promotion of an electron from the π to the π* molecular orbital. The excited state r0 molecular structure was determined by rotational analysis of high resolution LIF spectra to be r(PO) = 1.6710(2) Å, r(PH) = 1.4280(6) Å, θ(HPO) = 105.68(7)°, θ(HPH) = 93.3(2)°, and the out-of-plane angle = 66.8(2)°. The structural changes on electronic excitation, which include substantial increases in the PO bond length and out-of-plane angle, are as expected based on molecular orbital theory and our previous studies of the isoelectronic H2AsO, Cl2PS, and F2PS free radicals.

  16. 3D printed electromagnetic transmission and electronic structures fabricated on a single platform using advanced process integration techniques

    NASA Astrophysics Data System (ADS)

    Deffenbaugh, Paul Issac

    3D printing has garnered immense attention from many fields including in-office rapid prototyping of mechanical parts, outer-space satellite replication, garage functional firearm manufacture, and NASA rocket engine component fabrication. 3D printing allows increased design flexibility in the fabrication of electronics, microwave circuits and wireless antennas and has reached a level of maturity which allows functional parts to be printed. Much more work is necessary in order to perfect the processes of 3D printed electronics especially in the area of automation. Chapter 1 shows several finished prototypes of 3D printed electronics as well as newly developed techniques in fabrication. Little is known about the RF and microwave properties and applications of the standard materials which have been developed for 3D printing. Measurement of a wide variety of materials over a broad spectrum of frequencies up to 10 GHz using a variety of well-established measurement methods is performed throughout chapter 2. Several types of high frequency RF transmission lines are fabricated and valuable model-matched data is gathered and provided in chapter 3 for future designers' use. Of particular note is a fully 3D printed stripline which was automatically fabricated in one process on one machine. Some core advantages of 3D printing RF/microwave components include rapid manufacturing of complex, dimensionally sensitive circuits (such as antennas and filters which are often iteratively tuned) and the ability to create new devices that cannot be made using standard fabrication techniques. Chapter 4 describes an exemplary fully 3D printed curved inverted-F antenna.

  17. Antiproton cooling in the Fermilab Recycler Ring

    SciTech Connect

    Nagaitsev, S.; Bolshakov, A.; Broemmelsiek, D.; Burov, Alexey V.; Carlson, K.; Gattuso, C.; Hu, M.; Kazakevich, G.; Kramper, B.; Kroc, T.; Leibfritz, J.; Prost, L.; Pruss, S.; Saewert, G; Schmidt, C.W.; Seletskiy, S.; Shemyakin, A.; Sutherland, M.; Tupikov, V.; Warner, A.; Zenkevich, P.; /Fermilab /Moscow, ITEP /Novosibirsk, IYF /Rochester U.

    2005-12-01

    The 8.9-GeV/c Recycler antiproton storage ring is equipped with both stochastic and electron cooling systems. These cooling systems are designed to assist accumulation of antiprotons for the Tevatron collider operations. In this paper we report on an experimental demonstration of electron cooling of high-energy antiprotons. At the time of writing this report, the Recycler electron cooling system is routinely used in collider operations. It has helped to set recent peak luminosity records.

  18. Development of the Measurement System for the Search of an Electric Dipole Moment of the Electron with Laser-Cooled Francium Atoms

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Ishikawa, T.; Itoh, M.; Kato, K.; Kato, T.; Kawamura, H.; Nataraj, H. S.; Sato, T.; Uchiyama, A.; Aoki, T.; Furukawa, T.; Hatakeyama, A.; Hatanaka, K.; Imai, K.; Murakami, T.; Shimizu, Y.; Wakasa, T.; Yoshida, H. P.; Sakemi, Y.

    2014-03-01

    We plan to measure the permanent electric dipole moment (EDM) of the electron, which has the sensitivity to the CP violation in theories beyond the standard model by using the laser-cooled francium (Fr) atom. This paper reports the present status of the EDM measurement system. A high voltage application system was constructed in order to produce the strong electric field (100 kV/cm) needed for the experiment. After conditioning, the leakage current was 10 pA when a high voltage of 43 kV was applied. Also, a drift of an environmental field was measured at the planned location of the Fr-EDM experiment. The drift is suppressed at present down to the level of 10 pT by installing a 4-layermagnetic shield. Improvements are still needed to reach the required field stability of 1 fT.

  19. The Torsion-Inversion Energy Levels in the S1( n, π*) Electronic State of Acetaldehyde from High-Resolution Jet-Cooled Fluorescence Excitation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, H.; Lim, E. C.; Muñoz-Caro, C.; Niño, A.; Judge, R. H.; Moule, D. C.

    1996-01-01

    The laser-induced fluorescence excitation spectrum (LIF) of acetaldehyde that results from the emission from theS1(n, π*) electronic state has been observed under very high resolution with a CW pulse-amplified laser under jet-cooled conditions. The origins of seven bands were determined by rotational analyses with a rigid-rotor Hamiltonian. The origins were fitted to a set of levels that were obtained from a Hamiltonian that employed flexible torsion-wagging large amplitude coordinates. The potential surface derived from the fitting procedure yielded barriers to torsion and inversion of 721.43 and 585.13 cm-1, respectively. Minima in the potential hypersurface at θ = 58.6° and α = 35.7° defined the corresponding equilibrium positions for the torsion and wagging coordinates.

  20. Electronic spectroscopy of jet-cooled HCP+: molecular structure, phosphorus hyperfine structure, and Renner-Teller analysis.

    PubMed

    Sunahori, Fumie X; Zhang, Xiaopeng; Clouthier, Dennis J

    2007-09-14

    Laser-induced fluorescence spectra of jet-cooled HCP(+) and DCP(+) have been obtained with the pulsed discharge technique using HCPDCP and argon precursor mixtures. Transitions involving all of the excited state vibrations have been observed and a set of vibrational constants has been obtained. High-resolution spectra of the (2)Pi(32) components of the 0(0) (0) bands of both isotopomers have been recorded, and these spectra show resolved phosphorus hyperfine structure which allowed the determination of the excited state Fermi contact parameter. The B values were used to obtain the ground and excited state effective geometric parameters as r(0) (")(CH)=1.077(2) A, r(0) (")(CP)=1.6013(3) A, r(0) (')(CH)=1.082(2) A, and r(0) (')(CP)=1.5331(3) A. A Renner-Teller analysis of the ground state vibrational energy levels obtained from the literature was attempted. All of the observed levels of DCP(+) and the majority of those of HCP(+) were satisfactorily fitted with a standard Renner-Teller model, but three HCP(+) levels showed large systematic deviations which could not be accommodated by reassignments or improvements in the Fermi resonance Hamiltonian. Further improvements in the theory or in the experimental data will be needed to resolve this discrepancy.

  1. Experimental evaluation of cooling efficiency of the high performance cooling device

    NASA Astrophysics Data System (ADS)

    Nemec, Patrik; Malcho, Milan

    2016-06-01

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  2. The effect of Non- ionizing electromagnetic field with a frequency of 50 Hz in Rat ovary: A transmission electron microscopy study

    PubMed Central

    Khaki, Amir Afshin; Khaki, Arash; Ahmadi, Seyed Shahin

    2016-01-01

    Background: Recently, there are increasing concerns and interests about the potential effects of Electromagnetic Field (EMF) on both human and animal health. Objective: The goal of this study was to evaluate the harmful effects of 50 Hz non-ionizing EMF on rat oocytes. Materials and Methods: In this experimental study 30 rats were randomly taken from laboratory animals and their ags and weights were determined. These 3 month's old rats were randomly divided into 3 groups. The control group consisted of 10 rats without receiving any treatment and kept under normal conditions. Experimental group 1 (10 rats) received EMF for 8 weeks (3 weeks intrauterine +5 weeks after births) and experimental group 2 (10 rats) received EMF for 13 weeks (3 weeks intrauterine +10 weeks after birth). After removing the ovaries and isolating follicles, granulosa cells were fixed in glutaraldehyde and osmium tetroxide. Electron microscopy was used to investigate the traumatic effects of EMF on follicles. Results: In control group nucleus membrane and mitochondria in follicle’s cytoplasm seemed normal in appearance. Theca layer of primary follicles in experimental group was separated clearly, zona layer demonstrated trot with irregular thickness and ovarian stroma seemed isolated with dilated vessels showing infiltration. Conclusion: According to the results of this study, it can be concluded that EMF has harmful effects on the ovarian follicles. PMID:27200427

  3. Three-dimensional electromagnetic strong turbulence: Dependence of the statistics and dynamics of strong turbulence on the electron to ion temperature ratio

    NASA Astrophysics Data System (ADS)

    Graham, D. B.; Cairns, Iver H.; Skjaeraasen, O.; Robinson, P. A.

    2012-02-01

    The temperature ratio Ti/Te of ions to electrons affects both the ion-damping rate and the ion-acoustic speed in plasmas. The effects of changing the ion-damping rate and ion-acoustic speed are investigated for electrostatic strong turbulence and electromagnetic strong turbulence in three dimensions. When ion damping is strong, density wells relax in place and act as nucleation sites for the formation of new wave packets. In this case, the density perturbations are primarily density wells supported by the ponderomotive force. For weak ion damping, corresponding to low Ti/Te, ion-acoustic waves are launched radially outwards when wave packets dissipate at burnout, thereby increasing the level of density perturbations in the system and thus raising the level of scattering of Langmuir waves off density perturbations. Density wells no longer relax in place so renucleation at recent collapse sites no longer occurs, instead wave packets form in background low density regions, such as superpositions of troughs of propagating ion-acoustic waves. This transition is found to occur at Ti/Te ≈ 0.1. The change in behavior with Ti/Te is shown to change the bulk statistical properties, scaling behavior, spectra, and field statistics of strong turbulence. For Ti/Te>rsim0.1, the electrostatic results approach the predictions of the two-component model of Robinson and Newman, and good agreement is found for Ti/Te>rsim0.15.

  4. Electromagnetic Gyrokinetic Simulations

    SciTech Connect

    Wan, W

    2003-11-19

    A new electromagnetic kinetic electron {delta} particle simulation model has been demonstrated to work well at large values of plasma {beta} times the ion-to-electron mass ratio. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfven wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. zonal fields are found to be very weak, consistent with theoretical predictions for {beta} below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.

  5. COOLING DYNAMICS STUDIES AND SCENARIOS FOR THE RHIC COOLER.

    SciTech Connect

    FEDOTOV,A.V.; BEN-ZVI,I.; LITVINENKO, V.

    2005-05-16

    In this paper, we discuss various electron cooling dynamics studies for RHIC. We also present simulations [1] of various possibilities of using electron cooling at RHIC, which includes cooling at the top energy, pre-cooling at low energy, aspects of transverse and longitudinal cooling and their impact on the luminosity. Electron cooling at various collision energies both for heavy ions and protons is also discussed.

  6. Bremsstrahlung in the scattering of low-energy electrons by neutral atomic systems. [in atmosphere of sun and cool stars

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1985-01-01

    By elementary methods, the cross section for electron-atom and electron-molecule bremsstrahlung is computed in the limit when the incident electron energy is much less than Ry. The procedure employs the classical soft-photon emission probability formula for general (h/2pi)(omega), yielding a simple expression for the bremsstrahlung cross section in terms of the total elastic scattering cross section. The validity of the method is discussed, and results are compared with more elaborate and accurate calculations. Comparison is made with ('free-free') opacity calculations for the associated process at the temperature (6300 K) of the solar atmosphere. For chi sub omega = (h/2pi)(omega)/kT = 1, the computed absorption coefficient is within 2, 7, and 12 percent of accurate calculations for scatterings by H, He, and H2, respectively. The general dependence of the opacity on chi sub omega is described well by the simple formula, although the error is larger for higher chi sub omega; it is suggested that the inaccuracy at high frequencies is due to the failure of the soft-photon approximation.

  7. Cool & Connected

    EPA Pesticide Factsheets

    The Cool & Connected planning assistance program helps communities develop strategies and an action plan for using broadband to promote environmentally and economically sustainable community development.

  8. Cooling wall

    SciTech Connect

    Nosenko, V.I.

    1995-07-01

    Protecting the shells of blast furnaces is being resolved by installing cast iron cooling plates. The cooling plates become non-operational in three to five years. The problem is that defects occur in manufacturing the cooling plates. With increased volume and intensity of work placed on blast furnaces, heat on the cast iron cooling plates reduces their reliability that limits the interim repair period of blast furnaces. Scientists and engineers from the Ukraine studied this problem for several years, developing a new method of cooling the blast furnace shaft called the cooling wall. Traditional cast iron plates were replaced by a screen of steel tubes, with the area between the tubes filled with fireproof concrete. Before placing the newly developed furnace shaft into operation, considerable work was completed such as theoretical calculations, design, research of temperature fields and tension. Continual testing over many years confirms the value of this research in operating blast furnaces. The cooling wall works with water cooling as well as vapor cooling and is operating in 14 blast furnaces in the Ukraine and two in Russia, and has operated for as long as 14 years.

  9. Evidence that the maximum electron energy in hotspots of FR II galaxies is not determined by synchrotron cooling

    NASA Astrophysics Data System (ADS)

    Araudo, Anabella T.; Bell, Anthony R.; Crilly, Aidan; Blundell, Katherine M.

    2016-08-01

    It has been suggested that relativistic shocks in extragalactic sources may accelerate the highest energy cosmic rays. The maximum energy to which cosmic rays can be accelerated depends on the structure of magnetic turbulence near the shock but recent theoretical advances indicate that relativistic shocks are probably unable to accelerate particles to energies much larger than a PeV. We study the hotspots of powerful radiogalaxies, where electrons accelerated at the termination shock emit synchrotron radiation. The turnover of the synchrotron spectrum is typically observed between infrared and optical frequencies, indicating that the maximum energy of non-thermal electrons accelerated at the shock is ≲ TeV for a canonical magnetic field of ˜100 μG. Based on theoretical considerations we show that this maximum energy cannot be constrained by synchrotron losses as usually assumed, unless the jet density is unreasonably large and most of the jet upstream energy goes to non-thermal particles. We test this result by considering a sample of hotspots observed with high spatial resolution at radio, infrared and optical wavelengths.

  10. The mechanism of slow hot-hole cooling in lead-iodide perovskite: first-principles calculation on carrier lifetime from electron-phonon interaction.

    PubMed

    Kawai, Hiroki; Giorgi, Giacomo; Marini, Andrea; Yamashita, Koichi

    2015-05-13

    We report on an analysis of hot-carrier lifetimes from electron-phonon interaction in lead iodide perovskites using first-principles calculations. Our calculations show that the holes in CsPbI3 have very long lifetimes in the valence band region situated 0.6 eV below the top of the valence band. On the other hand, no long lifetime is predicted in PbI3(-). These different results reflect the different electronic density of states (DOSs) in the valence bands, that is, a small DOS for the former structure while a sharp DOS peak for the latter structure. We propose a reduction of the relaxation paths in the small valence DOS as being the origin of the slow hot-hole cooling. Analyzing the generalized Eliashberg functions, we predict that different perovskite A-site cations do not have an impact on the carrier decay mechanism. The similarity between the DOS structures of CsPbI3 and CH3NH3PbI3 enables us to extend the description of the decay mechanism of fully inorganic CsPbI3 to its organic-inorganic counterpart, CH3NH3PbI3.

  11. Cool Shelter

    ERIC Educational Resources Information Center

    Praeger, Charles E.

    2005-01-01

    Amid climbing energy costs and tightening budgets, administrators at school districts, colleges and universities are looking for all avenues of potential savings while promoting sustainable communities. Cool metal roofing can save schools money and promote sustainable design at the same time. Cool metal roofing keeps the sun's heat from collecting…

  12. The S1( 1A1)- S0( 1A1) Electronic Transition of Jet-Cooled o-Difluorobenzene

    NASA Astrophysics Data System (ADS)

    Swinn, Anna K.; Kable, Scott H.

    1998-09-01

    A detailed study of theS1(1A1)-S0(1A1) transition of jet-cooledo-difluorobenzene has been completed using the two techniques of laser-induced fluorescence excitation and dispersed, single vibronic level fluorescence spectroscopy. Analysis of over 60 dispersed fluorescence spectra resulted in both the assignment of 22 excited state vibrational frequencies and the confirmation of 23 ground state frequencies. The spectrum is dominated by Franck-Condon activity in totally symmetric vibrations with long progressions in the ring-breathing mode, ν9. By analogy with benzene and thepara- andmeta-substituted isomers, two vibronic coupling mechanisms are postulated to be responsible for the wealth of weaker symmetry-forbidden structure that has been observed. Single quantum changes inb2vibrations are postulated to appear due to first order vibronic coupling to a higher lyingB2electronic state. Combinations ofb1anda2modes are postulated to appear from second order vibronic coupling to anA1electronic state. This second order coupling causes a pronounced Duschinsky mixing among excited stateb1anda2modes with respect to their ground state counterparts. Franck-Condon factors are calculated for thea1progression-forming modes, anharmonic contributions are evaluated, one strong Fermi resonance is identified and analyzed, and the Duschinsky rotation matrix elements are evaluated for the most strongly affected modes, ν17and ν18. Several transitions in theoDFB-oDFB van der Waals dimer andoDFB-Ar complex are also assigned in the spectrum.

  13. Noise and Bandwidth Measurements of Diffusion-Cooled Nb Hot-Electron Bolometer Mixers at Frequencies Above the Superconductive Energy Gap

    NASA Technical Reports Server (NTRS)

    Wyss, R. A.; Karasik, B. S.; McGrath, W. R.; Bumble, B.; LeDuc, H.

    1999-01-01

    Diffusion-cooled Nb hot-electron bolometer (HEB) mixers have the potential to simultaneously achieve high intermediate frequency (IF) bandwidths and low mixer noise temperatures for operation at THz frequencies (above the superconductive gap energy). We have measured the IF signal bandwidth at 630 GHz of Nb devices with lengths L = 0.3, 0.2, and 0.1 micrometer in a quasioptical mixer configuration employing twin-slot antennas. The 3-dB EF bandwidth increased from 1.2 GHz for the 0.3 gm long device to 9.2 GHz for the 0.1 gm long device. These results demonstrate the expected 1/L squared dependence of the IF bandwidth at submillimeter wave frequencies for the first time, as well as the largest EF bandwidth obtained to date. For the 0.1 gm device, which had the largest bandwidth, the double sideband (DSB) noise temperature of the receiver was 320-470 K at 630 GHz with an absorbed LO power of 35 nW, estimated using the isothermal method. A version of this mixer with the antenna length scaled for operation at 2.5 THz has also been tested. A DSB receiver noise temperature of 1800 plus or minus 100 K was achieved, which is about 1,000 K lower than our previously reported results. These results demonstrate that large EF bandwidth and low-noise operation of a diffusion-cooled HEB mixer is possible at THz frequencies with the same device geometry.

  14. Beam cooling: Principles and achievements

    SciTech Connect

    Mohl, Dieter; Sessler, Andrew M.

    2003-05-18

    After a discussion of Liouville's theorem, and its implications for beam cooling, a brief description is given of each of the various methods of beam cooling: stochastic, electron, radiation, laser, ionization, etc. For each, we present the type of particle for which it is appropriate, its range of applicability, and the currently achieved degree of cooling. For each method we also discuss the present applications and, also, possible future developments and further applications.

  15. The effects of an electromagnetic field on the boundary tissue of the seminiferous tubules of the rat: A light and transmission electron microscope study.

    PubMed

    Khaki, A A; Tubbs, R S; Shoja, M M; Rad, J S; Khaki, A; Farahani, R M; Zarrintan, S; Nag, T C

    2006-08-01

    Human beings are unavoidably exposed to ambient electromagnetic fields (EMF) generated from various electrical devices and from power transmission lines. Controversy exists about the effects of EMF on various organs. One of the critical issues is that EMF may adversely affect the reproductive system. In order to examine this 30 rat pups were exposed to 50 Hz EMF (non-ionising radiation) during in utero development (approximately 3 weeks) and postnatal life (5 weeks). Groups of exposed rats were subsequently left in an environment free of EMF in order to observe recovery, if any, from the changes induced by EMF on the boundary tissue of the seminiferous tubules. The materials were processed and observed under a light and a transmission electron microscope. In the experimental rats boundary tissue was found disrupted at various layers. This tissue showed infoldings, which were perhaps due to the loss of collagen and reticular fibrils from the inner and outer non-cellular layers. The outer non-cellular layer, which was thinner than that of the control, was stripped away from the myoid cell layer in multiple regions, giving a "blister-like" appearance. The myoid cells showed fewer polyribosomes, pinocytotic vesicles and glycogen granules. Most mitochondria were found to lack cristae. The connections between individual myoid cells were apparently lost. There were signs of recovery in the boundary tissue following withdrawal from EMF exposure. These results suggest that EMF exposure may cause profound changes in the boundary tissue of the seminiferous tubules. Therefore exposure to EMF may result in pathological changes that lead to subfertility and infertility.

  16. Cooled railplug

    DOEpatents

    Weldon, William F.

    1996-01-01

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers.

  17. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a

  18. Anisotropic conducting films for electromagnetic radiation applications

    DOEpatents

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  19. Advanced Power Electronics and Electric Motors Annual Report -- 2013

    SciTech Connect

    Narumanchi, S.; Bennion, K.; DeVoto, D.; Moreno, G.; Rugh, J.; Waye, S.

    2015-01-01

    This report describes the research into advanced liquid cooling, integrated power module cooling, high temperature air cooled power electronics, two-phase cooling for power electronics, and electric motor thermal management by NREL's Power Electronics group in FY13.

  20. Cool School.

    ERIC Educational Resources Information Center

    Stephens, Suzanne

    1980-01-01

    The design for Floyd Elementary School in Miami (Florida) seeks to harness solar energy to provide at least 70 percent of the annual energy for cooling needs and 90 percent for hot water. (Author/MLF)

  1. Cool Vest

    NASA Technical Reports Server (NTRS)

    1982-01-01

    ILC, Dover Division's lightweight cooling garment, called Cool Vest was designed to eliminate the harmful effects of heat stress; increases tolerance time in hot environments by almost 300 percent. Made of urethane-coated nylon used in Apollo, it works to keep the body cool, circulating chilled water throughout the lining by means of a small battery-powered pump. A pocket houses the pump, battery and the coolant which can be ice or a frozen gel, a valve control allows temperature regulation. One version is self-contained and portable for unrestrained movement, another has an umbilical line attached to an external source of coolant, such as standard tap water, when extended mobility is not required. It is reported from customers that the Cool Vest pays for itself in increased productivity in very high temperatures.

  2. Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics.

    PubMed

    Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

    2014-03-07

    Increasing functional complexity and dimensional compactness of electronic devices have led to progressively higher power dissipation, mainly in the form of heat. Overheating of semiconductor-based electronics has been the primary reason for their failure. Such failures originate at the interface of the heat sink (commonly Cu and Al) and the substrate (silicon) due to the large mismatch in thermal expansion coefficients (∼300%) of metals and silicon. Therefore, the effective cooling of such electronics demands a material with both high thermal conductivity and a similar coefficient of thermal expansion (CTE) to silicon. Addressing this demand, we have developed a carbon nanotube-copper (CNT-Cu) composite with high metallic thermal conductivity (395 W m(-1) K(-1)) and a low, silicon-like CTE (5.0 ppm K(-1)). The thermal conductivity was identical to that of Cu (400 W m(-1) K(-1)) and higher than those of most metals (Ti, Al, Au). Importantly, the CTE mismatch between CNT-Cu and silicon was only ∼10%, meaning an excellent compatibility. The seamless integration of CNTs and Cu was achieved through a unique two-stage electrodeposition approach to create an extensive and continuous interface between the Cu and CNTs. This allowed for thermal contributions from both Cu and CNTs, resulting in high thermal conductivity. Simultaneously, the high volume fraction of CNTs balanced the thermal expansion of Cu, accounting for the low CTE of the CNT-Cu composite. The experimental observations were in good quantitative concurrence with the theoretically described 'matrix-bubble' model. Further, we demonstrated identical in-situ thermal strain behaviour of the CNT-Cu composite to Si-based dielectrics, thereby generating the least interfacial thermal strain. This unique combination of properties places CNT-Cu as an isolated spot in an Ashby map of thermal conductivity and CTE. Finally, the CNT-Cu composite exhibited the greatest stability to temperature as indicated by its low

  3. L- and U-shaped heat pipes thermal modules with twin fans for cooling of electronic system under variable heat source areas

    NASA Astrophysics Data System (ADS)

    Wang, Jung-Chang

    2014-04-01

    This study utilizes a versatile superposition method with thermal resistance network analysis to design and experiment on a thermal module with embedded six L-shaped or two U-shaped heat pipes and plate fins under different fan speeds and heat source areas. This type of heat pipes-heat sink module successively transfer heat capacity from a heat source to the heat pipes, the heat sink and their surroundings, and are suitable for cooling electronic systems via forced convection mechanism. The thermal resistances contain all major components from the thermal interface through the heat pipes and fins. Thermal performance testing shows that the lowest thermal resistances of the representative L- and U-shaped heat pipes-heat sink thermal modules are respectively 0.25 and 0.17 °C/W under twin fans of 3,000 RPM and 30 × 30 mm2 heat sources. The result of this work is a useful thermal management method to facilitate rapid analysis.

  4. Flow-Induced Vibration of a Reed in a Channel: Effect of Reed Shape on Convective Heat Transfer with Application to Electronic Cooling

    NASA Astrophysics Data System (ADS)

    Rips, Aaron; Shoele, Kourosh; Glezer, Ari; Mittal, Rajat

    2015-11-01

    Flow-induced vibration of a reed (a thin plate or flag) in a channel can improve heat transfer efficiency in forced convection applications, allowing for more heat transfer for the same fan power. Such systems have wide ranging applications in electronic and power cooling. We investigate the effect of 3D reed shape on heat transfer enhancement. To study 3D effects, we first use 2D fluid-structure interaction (FSI) simulations of an optimized reed (in terms of mass and stiffness) to generate a prescribed reed motion. We then apply that motion to a pseudo 3D reed (i.e. infinitely stiff in the spanwise direction) and study the heat transfer enhancement in a 3D channel. This method allows us to explore a large parameter space exhaustively, and using this method, we examine the effect of several parameters, such as reed planform and spanwise gap, on the heat transfer enhancements for forced convection in a channel. Simulations indicate that these geometrical feature have a significant effect on the vortex dynamics in the wake as well as the heat transfer efficiency. This work was supported by grants from AFOSR, EPRI and NSF.

  5. Superconducting electromagnetic thruster

    SciTech Connect

    Meng, J.

    1993-02-11

    An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

  6. Stability of cooled beams

    NASA Astrophysics Data System (ADS)

    Bosser, J.; Carli, C.; Chanel, M.; Madsen, N.; Maury, S.; Möhl, D.; Tranquille, G.

    2000-02-01

    Because of their high density together with extremely small spreads in betatron frequency and momentum, cooled beams are very vulnerable to incoherent and coherent space-charge effects and instabilities. Moreover, the cooling system itself, i.e. the electron beam in the case of e-cooling, presents large linear and non-linear "impedances" to the circulating ion beam, in addition to the usual beam-environment coupling impedances of the storage ring. Beam blow-up and losses, attributed to such effects, have been observed in virtually all the existing electron cooling rings. The adverse effects seem to be more pronounced in those rings, like CELSIUS, that are equipped with a cooler capable of reaching the presently highest energy (100-300 keV electrons corresponding to 180-560 MeV protons). The stability conditions will be revisited with emphasis on the experience gained at LEAR. It will be argued that for all present coolers, three conditions are necessary (although probably not sufficient) for the stability of intense cold beams: (i) operation below transition energy, (ii) active damping to counteract coherent instability, and (iii) careful control of the e-beam neutralisation. An extrapolation to the future "medium energy coolers", planned to work for (anti)protons of several GeV, will also be attempted.

  7. Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2; Waves, Precipitating Ring Current Ions, and Thermal Electron Heating

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

    2006-01-01

    This paper is dedicated to further presentations and discussions of the results from our new global self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2006; here referred to as Paper 1]. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation [for details see Paper 1]. To demonstrate the effects of the EMIC wave propagation and refraction on the RC proton precipitations and heating of the thermal plasmaspheric electrons we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. Firstly, the wave induced precipitations have a quite fine structure, and are highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 (raised dot) 10(exp 6) [(cm (raised dot) s (raised dot) sr)(sup -l)] are observed during the main and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not simply connected to the most intense EMIC waves. The character of the EMIC wave power spectral density distribution over the equatorial wave normal angle is an extremely crucial for the effectiveness of the RC ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from other ring current model [Kozyra et al., 1997] reveals that although we observe a qualitative agreement between localizations of the wave induced fluxes in the models, there is no quantitative agreement between the magnitudes of these fluxes. These differences are mainly due to a qualitative difference between the characters of the EMIC wave power spectral density distributions over the equatorial wave normal angle. Finally, the two energy sources to the

  8. An experimental and ab initio study of the electronic spectrum of the jet-cooled F{sub 2}BO free radical

    SciTech Connect

    Grimminger, Robert; Clouthier, Dennis J.; Sheridan, Phillip M.

    2014-04-28

    We have studied the B{sup ~} {sup 2}A{sub 1}–X{sup ~} {sup 2}B{sub 2} laser-induced fluorescence (LIF) spectrum of the jet-cooled F{sub 2}BO radical for the first time. The transition consists of a strong 0{sub 0}{sup 0} band at 446.5 nm and eight weak sequence bands to shorter wavelengths. Single vibronic level emission spectra obtained by laser excitation of individual levels of the B{sup ~} state exhibit two electronic transitions: a very weak, sparse B{sup ~}–X{sup ~} band system in the 450–500 nm region and a stronger, more extensive set of B{sup ~} {sup 2}A{sub 1}–A{sup ~} {sup 2}B{sub 1} bands in the 580–650 nm region. We have also performed a series of high level ab initio calculations to predict the electronic energies, molecular structures, vibrational frequencies, and rotational and spin-rotation constants in the X{sup ~} {sup 2}B{sub 2}, A{sup ~2}B{sub 1} and B{sup ~} {sup 2}A{sub 1} electronic states as an aid to the analysis of the experimental data. The theoretical results have been used as input for simulations of the rotationally resolved B{sup ~} {sup 2}A{sub 1}–X{sup ~} {sup 2}B{sub 2} 0{sub 0}{sup 0} LIF band and Franck-Condon profiles of the LIF and single vibronic level emission spectra. The agreement between the simulations obtained with purely ab initio parameters and the experimental spectra validates the geometries calculated for the ground and excited states and the conclusion that the radical has C{sub 2v} symmetry in the X{sup ~}, A{sup ~}, and B{sup ~} states. The spectra provide considerable new information about the vibrational energy levels of the X{sup ~} and A{sup ~} states, but very little for the B{sup ~} state, due to the very restrictive Franck-Condon factors in the LIF spectra.

  9. Effectiveness-weighted control method for a cooling system

    SciTech Connect

    Campbell, Levi A.; Chu, Richard C.; David, Milnes P.; Ellsworth Jr., Michael J.; Iyengar, Madhusudan K.; Schmidt, Roger R.; Simons, Robert E.

    2015-12-15

    Energy efficient control of cooling system cooling of an electronic system is provided based, in part, on weighted cooling effectiveness of the components. The control includes automatically determining speed control settings for multiple adjustable cooling components of the cooling system. The automatically determining is based, at least in part, on weighted cooling effectiveness of the components of the cooling system, and the determining operates to limit power consumption of at least the cooling system, while ensuring that a target temperature associated with at least one of the cooling system or the electronic system is within a desired range by provisioning, based on the weighted cooling effectiveness, a desired target temperature change among the multiple adjustable cooling components of the cooling system. The provisioning includes provisioning applied power to the multiple adjustable cooling components via, at least in part, the determined control settings.

  10. Effectiveness-weighted control of cooling system components

    DOEpatents

    Campbell, Levi A.; Chu, Richard C.; David, Milnes P.; Ellsworth Jr., Michael J.; Iyengar, Madhusudan K.; Schmidt, Roger R.; Simmons, Robert E.

    2015-12-22

    Energy efficient control of cooling system cooling of an electronic system is provided based, in part, on weighted cooling effectiveness of the components. The control includes automatically determining speed control settings for multiple adjustable cooling components of the cooling system. The automatically determining is based, at least in part, on weighted cooling effectiveness of the components of the cooling system, and the determining operates to limit power consumption of at least the cooling system, while ensuring that a target temperature associated with at least one of the cooling system or the electronic system is within a desired range by provisioning, based on the weighted cooling effectiveness, a desired target temperature change among the multiple adjustable cooling components of the cooling system. The provisioning includes provisioning applied power to the multiple adjustable cooling components via, at least in part, the determined control settings.

  11. Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics

    NASA Astrophysics Data System (ADS)

    Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

    2014-02-01

    Increasing functional complexity and dimensional compactness of electronic devices have led to progressively higher power dissipation, mainly in the form of heat. Overheating of semiconductor-based electronics has been the primary reason for their failure. Such failures originate at the interface of the heat sink (commonly Cu and Al) and the substrate (silicon) due to the large mismatch in thermal expansion coefficients (~300%) of metals and silicon. Therefore, the effective cooling of such electronics demands a material with both high thermal conductivity and a similar coefficient of thermal expansion (CTE) to silicon. Addressing this demand, we have developed a carbon nanotube-copper (CNT-Cu) composite with high metallic thermal conductivity (395 W m-1 K-1) and a low, silicon-like CTE (5.0 ppm K-1). The thermal conductivity was identical to that of Cu (400 W m-1 K-1) and higher than those of most metals (Ti, Al, Au). Importantly, the CTE mismatch between CNT-Cu and silicon was only ~10%, meaning an excellent compatibility. The seamless integration of CNTs and Cu was achieved through a unique two-stage electrodeposition approach to create an extensive and continuous interface between the Cu and CNTs. This allowed for thermal contributions from both Cu and CNTs, resulting in high thermal conductivity. Simultaneously, the high volume fraction of CNTs balanced the thermal expansion of Cu, accounting for the low CTE of the CNT-Cu composite. The experimental observations were in good quantitative concurrence with the theoretically described `matrix-bubble' model. Further, we demonstrated identical in-situ thermal strain behaviour of the CNT-Cu composite to Si-based dielectrics, thereby generating the least interfacial thermal strain. This unique combination of properties places CNT-Cu as an isolated spot in an Ashby map of thermal conductivity and CTE. Finally, the CNT-Cu composite exhibited the greatest stability to temperature as indicated by its low thermal

  12. Cryogenic Cooling of Infrared Electronics

    DTIC Science & Technology

    1986-05-01

    Stirling cryocooler one of the most compact, efficient, and reliable of the devices yet commercialized. 21 A wide variety of Stirling cryocoolers have...Considerable effort has been expended in improving the components of the Stirling cryocooler , especially in terms of minimizing the wear of the...classes of devices, the choice depending on the application. One of the early contemporary integrated mechanical Stirling cryocoolers was developed by

  13. Cooling Vest

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Because quadriplegics are unable to perspire below the level of spinal injury, they cannot tolerate heat stress. A cooling vest developed by Ames Research Center and Upjohn Company allows them to participate in outdoor activities. The vest is an adaptation of Ames technology for thermal control garments used to remove excess body heat of astronauts. The vest consists of a series of corrugated channels through which cooled water circulates. Its two outer layers are urethane coated nylon, and there is an inner layer which incorporates the corrugated channels. It can be worn as a backpack or affixed to a wheelchair. The unit includes a rechargeable battery, mini-pump, two quart reservoir and heat sink to cool the water.

  14. Cooled railplug

    DOEpatents

    Weldon, W.F.

    1996-05-07

    The railplug is a plasma ignitor capable of injecting a high energy plasma jet into a combustion chamber of an internal combustion engine or continuous combustion system. An improved railplug is provided which has dual coaxial chambers (either internal or external to the center electrode) that provide for forced convective cooling of the electrodes using the normal pressure changes occurring in an internal combustion engine. This convective cooling reduces the temperature of the hot spot associated with the plasma initiation point, particularly in coaxial railplug configurations, and extends the useful life of the railplug. The convective cooling technique may also be employed in a railplug having parallel dual rails using dual, coaxial chambers. 10 figs.

  15. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  16. Electromagnetic strong plasma turbulence

    SciTech Connect

    Melatos, A.; Jenet, F. A.; Robinson, P. A.

    2007-02-15

    The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c{<=}v{<=}0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v{>=}0.1c to just free eigenstates for v{<=}0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

  17. Electromagnetic Environmental Effects System Testing

    DTIC Science & Technology

    2009-09-02

    4) Anritsu 68369A/NV. e. Stub Radiator. f . Capacitor, 10 microfara, Solar Electronics 6512-106R, 7113-106R, or similar. g. LISNs, Solar ...GENERATED ELECTROSTATIC DISCHARGE (HESD) ............................................................................. E-1 F . PRECIPITATION...STATIC (P-STATIC) ................................................ F -1 G. HAZARDS OF ELECTROMAGNETIC RADIATION TO FUEL (HERF

  18. Cooling vest

    NASA Technical Reports Server (NTRS)

    Kosmo, J.; Kane, J.; Coverdale, J.

    1977-01-01

    Inexpensive vest of heat-sealable urethane material, when strapped to person's body, presents significant uncomplicated cooling system for environments where heavy accumulation of metabolic heat exists. Garment is applicable to occupations where physical exertion is required under heavy protective clothing.

  19. Electromagnetic Transport From Microtearing Mode Turbulence

    SciTech Connect

    Guttenfelder, W; Kaye, S M; Nevins, W M; Wang, E; Bell, R E; Hammett, G W; LeBlanc, B P; Mikkelsen, D R

    2011-03-23

    This Letter presents non-linear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high beta discharge in the National Spherical Torus Experiment (NSTX). The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

  20. Cooling Mechanical Oscillators by Coherent Control

    NASA Astrophysics Data System (ADS)

    Frimmer, Martin; Gieseler, Jan; Novotny, Lukas

    2016-10-01

    In optomechanics, electromagnetic fields are harnessed to control a single mode of a mechanically compliant system, while other mechanical degrees of freedom remain unaffected due to the modes' mutual orthogonality and high quality factor. Extension of the optical control beyond the directly addressed mode would require a controlled coupling between mechanical modes. Here, we introduce an optically controlled coupling between two oscillation modes of an optically levitated nanoparticle. We sympathetically cool one oscillation mode by coupling it coherently to the second mode, which is feedback cooled. Furthermore, we demonstrate coherent energy transfer between mechanical modes and discuss its application for ground-state cooling.

  1. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-01-01

    The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  2. Radiative cooling for thermophotovoltaic systems

    NASA Astrophysics Data System (ADS)

    Zhou, Zhiguang; Sun, Xingshu; Bermel, Peter

    2016-09-01

    Radiative cooling has recently garnered a great deal of attention for its potential as an alternative method for photovoltaic thermal management. Here, we will consider the limits of radiative cooling for thermal management of electronics broadly, as well as a specific application to thermal power generation. We show that radiative cooling power can increase rapidly with temperature, and is particularly beneficial in systems lacking standard convective cooling. This finding indicates that systems previously operating at elevated temperatures (e.g., 80°C) can be passively cooled close to ambient under appropriate conditions with a reasonable cooling area. To examine these general principles for a previously unexplored application, we consider the problem of thermophotovoltaic (TPV) conversion of heat to electricity via thermal radiation illuminating a photovoltaic diode. Since TPV systems generally operate in vacuum, convective cooling is sharply limited, but radiative cooling can be implemented with proper choice of materials and structures. In this work, realistic simulations of system performance are performed using the rigorous coupled wave analysis (RCWA) techniques to capture thermal emitter radiation, PV diode absorption, and radiative cooling. We subsequently optimize the structural geometry within realistic design constraints to find the best configurations to minimize operating temperature. It is found that low-iron soda-lime glass can potentially cool the PV diode by a substantial amount, even to below ambient temperatures. The cooling effect can be further improved by adding 2D-periodic photonic crystal structures. We find that the improvement of efficiency can be as much as an 18% relative increase, relative to the non-radiatively cooled baseline, as well as a potentially significant improvement in PV diode lifetime.

  3. Cooling and recombination processes in cometary plasma

    NASA Technical Reports Server (NTRS)

    Wallis, M. K.; Ong, R. S. B.

    1976-01-01

    The ion electron plasma in comets is examined for cooling processes which result from its interactions with the neutral coma. A cometary coma model is formulated that is composed predominantly of H2O and its decomposition products where electrons are cooled in a variety of processes at rates varying with energy. It is shown that solar plasma plus accumulated cometary ions and electrons is affected very strongly as it flows into the coma. The electrons are rapidly cooled and all but some 10% of the ions undergo charge exchange. Photodissociation of H2O is assumed where ion electron recombination is the dominant loss process.

  4. Cool Sportswear

    NASA Technical Reports Server (NTRS)

    1982-01-01

    New athletic wear design based on the circulating liquid cooling system used in the astronaut's space suits, allows athletes to perform more strenuous activity without becoming overheated. Techni-Clothes gear incorporates packets containing a heat-absorbing gel that slips into an insulated pocket of the athletic garment and is positioned near parts of the body where heat transfer is most efficient. A gel packet is good for about one hour. Easily replaced from a supply of spares in an insulated container worn on the belt. The products, targeted primarily for runners and joggers and any other athlete whose performance may be affected by hot weather, include cooling headbands, wrist bands and running shorts with gel-pack pockets.

  5. On steady electromagnetic equilibria

    NASA Astrophysics Data System (ADS)

    Lehnert, B.

    1986-12-01

    The existence of steady electromagnetic equilibrium states predicted by an extended Lorentz invariant formulation of Maxwell's equations is analyzed. General equilibrium solutions are outlined which lead to integrated field quantities of the system, such as total charge qo, magnetic moment Mo, mass mo and angular momentum so. The quantization of moMo/qo in terms of Bohr magnetons is shown to be equivalent to the proposed resonance condition of circulating self-confined radiation. Exact equilibrium solutions were deduced in two simple cases, thereby leading to a so of the same order as that of the electron, and to a qo one order of magnitude larger than the electronic charge. A variational procedure is suggested in search for states of minimum charge, under the subsidiary quantum conditions on moMo/qo and so, i.e., by varying the profile of the electric space charge distribution.

  6. Cooling technique

    DOEpatents

    Salamon, Todd R; Vyas, Brijesh; Kota, Krishna; Simon, Elina

    2017-01-31

    An apparatus and a method are provided. Use is made of a wick structure configured to receive a liquid and generate vapor in when such wick structure is heated by heat transferred from heat sources to be cooled off. A vapor channel is provided configured to receive the vapor generated and direct said vapor away from the wick structure. In some embodiments, heat conductors are used to transfer the heat from the heat sources to the liquid in the wick structure.

  7. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments.

  8. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, T.E.

    1996-11-19

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments. 12 figs.

  9. Electromagnetic radiation from beam-plasma instabilities

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.; Whelan, D. A.

    1982-01-01

    The mechanism by which unstable electrostatic waves of an electron-beam plasma system are converted into observed electromagnetic waves is of great current interest in space plasma physics. Electromagnetic radiation arises from both natural beam-plasma systems, e.g., type III solar bursts and kilometric radiation, and from man-made electron beams injected from rockets and spacecraft. In the present investigation the diagnostic difficulties encountered in space plasmas are overcome by using a large laboratory plasma. A finite diameter (d approximately equal to 0.8 cm) electron beam is injected into a uniform quiescent magnetized afterglow plasma of dimensions large compared with electromagnetic wavelength. Electrostatic waves grow, saturate and decay within the uniform central region of the plasma volume so that linear mode conversion on density gradients can be excluded as a possible generation mechanism for electromagnetic waves.

  10. Electromagnetic launcher

    SciTech Connect

    Laskaris, E.T.; Chari, M.V.K.

    1990-11-20

    This paper describes an electromagnetic launcher. It comprises: a stationary superconductive coil situated coaxially in a cylindrical vacuum vessel for providing a magnetic field. The superconductive coil having a central aperture, the vacuum vessel having an axially extending bore passing through the central aperture of the superconducting coil; a resistive coil situated coaxially with the superconductive coil and movable axially relative to the stationary superconductive coil, the outer diameter of the resistive coil being smaller than the inner diameter of the bore permitting the resistive coil to pass therethrough; launch activating means coupled to the resistive coil. The launch activating means comprising a shaft joined at one end to the resistive coil, a tube open at both ends, a sliding piston situated in the tube and connected to the other end of the shaft; and power supply means coupled to the resistive coil for providing current of a desired direction and magnitude, so that energization of the resistive coil in the presence of the radial field component of the magnetic field of the superconductive coil creates an axial force on the movable coil, the direction and magnitude of which is dependent on the direction and magnitude of the current in the resistive coil.

  11. Electromagnetic launchers

    NASA Astrophysics Data System (ADS)

    Kolm, H.; Mongeau, P.; Williams, F.

    1980-09-01

    Recent advances in energy storage, switching and magnet technology make electromagnetic acceleration a viable alternative to chemical propulsion for certain tasks, and a means to perform other tasks not previously feasible. Applications include the acceleration of gram-size particles for hypervelocity research and the initiation of fusion by impact, a replacement for chemically propelled artillery, the transportation of cargo and personnel over inaccessible terrain, and the launching of space vehicles to supply massive space operations, and for the disposal of nuclear waste. The simplest launcher of interest is the railgun, in which a short-circuit slide or an arc is driven along two rails by direct current. The most sophisticated studied thus far is the mass driver, in which a superconducting shuttle bucket is accelerated by a line of pulse coils energized by capacitors at energy conversion efficiencies better than 90%. Other accelerators of interest include helical, brush-commutated motors, discrete coil arc commutated drivers, flux compression momentum transformers, and various hybrid electrochemical devices.

  12. Cooling device

    SciTech Connect

    Teske, L.

    1984-02-21

    A cooling device is claimed for coal dust comprising a housing, a motor-driven conveyor system therein to transport the coal dust over coolable trays in the housing and conveyor-wheel arms of spiral curvature for moving the coal dust from one or more inlets to one or more outlets via a series of communicating passages in the trays over which the conveyor-wheel arms pass under actuation of a hydraulic motor mounted above the housing and driving a vertical shaft, to which the conveyor-wheel arms are attached, extending centrally downwardly through the housing.

  13. REACTOR COOLING

    DOEpatents

    Quackenbush, C.F.

    1959-09-29

    A nuclear reactor with provisions for selectively cooling the fuel elements is described. The reactor has a plurality of tubes extending throughout. Cylindrical fuel elements are disposed within the tubes and the coolant flows through the tubes and around the fuel elements. The fuel elements within the central portion of the reactor are provided with roughened surfaces of material. The fuel elements in the end portions of the tubes within the reactor are provlded with low conduction jackets and the fuel elements in the region between the central portion and the end portions are provided with smooth surfaces of high heat conduction material.

  14. Compatibility, Electromagnetic

    DTIC Science & Technology

    1979-10-12

    maicatons-el.ectronaas *C-E) equipment. It describes procedures zo dcr=Lne that C--c. *qtu~ent and symceo.s Incorporaz.s the basr availible technologyi ior...numerous locatio)ns for mobile testing, a mobile electronic countermeasures envir=nmeat genorator installation, a mobile and seaiLwbila onvironaftnt

  15. Electromagnetically driven liquid iris

    NASA Astrophysics Data System (ADS)

    Jang, Deasung; Jeong, Jin Won; Lee, Dae Young; Kim, Dae Geun; Chung, Sang Kug

    2016-11-01

    This paper describes a tunable liquid iris driven by electromagnetic actuation for miniature cameras. To examine the magnetic effect on a ferrofluid, the contact angle modification of a sessile ferrofluid droplet is tested using a neodymium magnet and an electric coil which 2.5 A current is applied to. The contact angle variations of the ferrofluid droplet for each test are 21.3 and 18.1 degrees, respectively. As a proof of concept, a pretest of a tunable iris actuated by electromagnetic effect is performed by using a hollow cylinder cell. As applying the current, the aperture diameter is adjusted from 4.06 mm at 0A to 3.21 mm at 2.0A. Finally, a tunable liquid iris (9 x 9 x 2 mm3) , consisting of two connected circular microchannels, is realized using MEMS technology. the aperture diameter of the tunable liquid iris is able to be modified from 1.72 mm at 0 A to 1.15 mm at 2.6 A. This tunable optical iris has potential applications not only for portable electronic devices but also in biomedical fields such as optical coherence tomography and microsurgery. This work was supported by 2016 Research Fund of Myongji University.

  16. The HPS electromagnetic calorimeter

    DOE PAGES

    Balossino, I.; Baltzell, N.; Battaglieri, M.; ...

    2017-02-22

    The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called "heavy photon". Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015-2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. Finally, the detector is a homogeneous calorimeter, made of 442 lead-tungsten (PbWOmore » $$_4$$) scintillating crystals, each read-out by an avalanche photodiode coupled to a custom trans-impedance amplifier.« less

  17. Supercooling effects in Cu-10 wt pct Co alloys solidified at different cooling rates

    NASA Technical Reports Server (NTRS)

    Munitz, A.; Elder-Randall, S. P.; Abbaschian, R.

    1992-01-01

    Electromagnetic levitation and electron beam surface melting were employed to study the effects of supercooling and cooling rate on the solidification of Cu-10 wt pct Co alloys. Two major effects were observed in the supercooled alloys: the nucleation of a metastable copper-rich phase which contains 13 wt pct to 20 wt pct Co in samples supercooled between 105 and 150 K and liquid phase separation which occurs in samples supercooled 150 K or more. The microstructure of the electron beam melted surfaces consisted of very fine spheres which were similar to those of the sample supercooled more than 150 K but with a refined microstructure. The results indicate that a dynamic bulk supercooling of 150 K may exist in the molten pool during the solidification of electron beam melted surfaces.

  18. An assessment of hazards caused by electromagnetic interaction on humans present near short-wave physiotherapeutic devices of various types including hazards for users of electronic active implantable medical devices (AIMD).

    PubMed

    Karpowicz, Jolanta; Gryz, Krzysztof

    2013-01-01

    Leakage of electromagnetic fields (EMF) from short-wave radiofrequency physiotherapeutic diathermies (SWDs) may cause health and safety hazards affecting unintentionally exposed workers (W) or general public (GP) members (assisting patient exposed during treatment or presenting there for other reasons). Increasing use of electronic active implantable medical devices (AIMDs), by patients, attendants, and workers, needs attention because dysfunctions of these devices may be caused by electromagnetic interactions. EMF emitted by 12 SWDs (with capacitive or inductive applicators) were assessed following international guidelines on protection against EMF exposure (International Commission on Nonionizing Radiation Protection for GP and W, new European directive 2013/35/EU for W, European Recommendation for GP, and European Standard EN 50527-1 for AIMD users). Direct EMF hazards for humans near inductive applicators were identified at a distance not exceeding 45 cm for W or 62 cm for GP, but for AIMD users up to 90 cm (twice longer than that for W and 50% longer than that for GP because EMF is pulsed modulated). Near capacitive applicators emitting continuous wave, the corresponding distances were: 120 cm for W or 150 cm for both-GP or AIMD users. This assessment does not cover patients who undergo SWD treatment (but it is usually recommended for AIMD users to be careful with EMF treatment).

  19. Electromagnetic vibration process for producing bulk metallic glasses.

    PubMed

    Tamura, Takuya; Amiya, Kenji; Rachmat, Rudi S; Mizutani, Yoshiki; Miwa, Kenji

    2005-04-01

    It is known that the cooling rate from the liquid state is an important factor in the production of bulk metallic glasses. However, the effects of other factors such as electric and magnetic fields have not been thoroughly investigated. Here, we present a new method for producing bulk metallic glasses by using electromagnetic vibrations with simultaneous imposition of an alternating electric current and a magnetic field. This method was found to be effective in enhancing apparent glass-forming ability in Mg65-Cu25-Y10 (atomic percent) alloys. Indeed, larger bulk metallic glasses could be obtained by the electromagnetic vibration process under the same cooling conditions. We presume that disappearance or decrement of clusters by the electromagnetic vibrations applied to the liquid state cause suppression of crystal nucleation. This electromagnetic vibration process should be effective in other bulk metallic glass systems if the clusters in the liquid state cause the crystal nucleation.

  20. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  1. A Determination of the Risk of Intentional and Unintentional Electromagnetic Radiation Emitters Degrading Installed Components in Closed Electromagnetic Environments

    DTIC Science & Technology

    2015-06-01

    transfer can be advantageous in various applications. Exposing sensitive electronic components to a time-varying electromagnetic field increases the...risk of an electronic upset in those components that will degrade the functionality of installed systems. This risk determination should provide a...applications. Exposing sensitive electronic components to a time-varying electromagnetic field increases the risk of an electronic upset in those

  2. Nucleate Boiling Heat Transfer Study of Direct Immersion Cooling of a 3X3 Array of Vertically Orientated Electronic Components in a Dielectric Liquid

    DTIC Science & Technology

    1992-09-01

    73 v APPENDIX B. SAMPLE CALCULATIONS ............................. 81 A. DETERMINATION OF INPUT POWER OF CHIP...produced by the Melcor corporation and were utilized to remove the heat from the condenser. The cooling devices were normally operated at 2.0 volts and 0.4...DETERMINATION OF INPUT POWER OF CHIP For this sample calculation, the power drop across chip 2 was determined: Powerl- Voltl*Volt2/Resistl where Voltl and

  3. COHERENCE PROPERTIES OF ELECTROMAGNETIC RADIATION,

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , COHERENT SCATTERING), (*COHERENT SCATTERING, ELECTROMAGNETIC RADIATION ), LIGHT, INTERFERENCE, INTENSITY, STATISTICAL FUNCTIONS, QUANTUM THEORY, BOSONS, INTERFEROMETERS, CHINA

  4. Electromagnetic Education in India

    ERIC Educational Resources Information Center

    Bajpai, Shrish; Asif, Siddiqui Sajida; Akhtar, Syed Adnan

    2016-01-01

    Out of the four fundamental interactions in nature, electromagnetics is one of them along with gravitation, strong interaction and weak interaction. The field of electromagnetics has made much of the modern age possible. Electromagnets are common in day-to-day appliances and are becoming more conventional as the need for technology increases.…

  5. Fundamentals of Electromagnetic Phenomena

    NASA Astrophysics Data System (ADS)

    Lorrain, Paul; Corson, Dale R.; Lorrain, Francois

    Based on the classic Electromagnetic Fields and Waves by the same authors, Fundamentals of Electromagnetic Phenomena capitalizes on the older text's traditional strengths--solid physics, inventive problems, and an experimental approach--while offering a briefer, more accessible introduction to the basic principles of electromagnetism.

  6. Actively controlling coolant-cooled cold plate configuration

    DOEpatents

    Chainer, Timothy J.; Parida, Pritish R.

    2016-04-26

    Cooling apparatuses are provided to facilitate active control of thermal and fluid dynamic performance of a coolant-cooled cold plate. The cooling apparatus includes the cold plate and a controller. The cold plate couples to one or more electronic components to be cooled, and includes an adjustable physical configuration. The controller dynamically varies the adjustable physical configuration of the cold plate based on a monitored variable associated with the cold plate or the electronic component(s) being cooled by the cold plate. By dynamically varying the physical configuration, the thermal and fluid dynamic performance of the cold plate are adjusted to, for example, optimally cool the electronic component(s), and at the same time, reduce cooling power consumption used in cooling the electronic component(s). The physical configuration can be adjusted by providing one or more adjustable plates within the cold plate, the positioning of which may be adjusted based on the monitored variable.

  7. Electromagnetic pulses bone healing booster

    NASA Astrophysics Data System (ADS)

    Sintea, S. R.; Pomazan, V. M.; Bica, D.; Grebenisan, D.; Bordea, N.

    2015-11-01

    Posttraumatic bone restoration triggered by the need to assist and stimulate compensatory bone growth in periodontal condition. Recent studies state that specific electromagnetic stimulation can boost the bone restoration, reaching up to 30% decrease in recovery time. Based on the existing data on the electromagnetic parameters, a digital electronic device is proposed for intra oral mounting and bone restoration stimulation in periodontal condition. The electrical signal is applied to an inductive mark that will create and impregnate magnetic field in diseased tissue. The device also monitors the status of the electromagnetic field. Controlled wave forms and pulse frequency signal at programmable intervals are obtained with optimized number of components and miniaturized using surface mounting devices (SMD) circuits and surface mounting technology (SMT), with enhanced protection against abnormal current growth, given the intra-oral environment. The system is powered by an autonomous power supply (battery), to limit the problems caused by powering medical equipment from the main power supply. Currently the device is used in clinical testing, in cycles of six up to twelve months. Basic principles for the electrical scheme and algorithms for pulse generation, pulse control, electromagnetic field control and automation of current monitoring are presented, together with the friendly user interface, suitable for medical data and patient monitoring.

  8. Electromagnetic effects on transportation systems

    SciTech Connect

    Morris, M.E.; Dinallo, M.A.

    1996-05-01

    Electronic and electrical system protection design can be used to eliminate deleterious effects from lightning, electromagnetic interference, and electrostatic discharges. Evaluation of conventional lightning protection systems using advanced computational modeling in conjunction with rocket-triggered lightning tests suggests that currently used lightning protection system design rules are inadequate and that significant improvements in best practices used for electronic and electrical system protection designs are possible. A case study of lightning induced upset and failure of a railway signal and control system is sketched.

  9. Principles of electromagnetic theory

    SciTech Connect

    Kovetz, A.H. )

    1990-01-01

    This book emphasizes the fundamental understanding of the laws governing the behavior of charge and current carrying bodies. Electromagnetism is presented as a classical theory, based-like mechanics-on principles that are independent of the atomic constitution of matter. This book is unique among electromagnetic texts in its treatment of the precise manner in which electromagnetism is linked to mechanics and thermodynamics. Applications include electrostriction, piezoelectricity, ferromagnetism, superconductivity, thermoelectricity, magnetohydrodynamics, radiation from charged particles, electromagnetic wave propagation and guided waves. There are many worked examples of dynamical and thermal effects of electromagnetic fields, and of effects resulting from the motion of bodies.

  10. Renewable Heating and Cooling

    EPA Pesticide Factsheets

    Renewable heating and cooling is a set of alternative resources and technologies that can be used in place of conventional heating and cooling technologies for common applications such as water heating, space heating, space cooling and process heat.

  11. Writing about Cool: Teaching Hypertext as Juxtaposition.

    ERIC Educational Resources Information Center

    Rice, Jeff

    2003-01-01

    Frames a rhetoric of "cool" by describing how temporal events in the respective fields of writing, technology, and cultural studies seen in juxtaposition provide a model for electronic research. Examines how students working with hypertext, drawing from these works and juxtapositions, are able to not only write about cool, but are able…

  12. Semiconductor cooling by thin-film thermocouples

    NASA Technical Reports Server (NTRS)

    Tick, P. A.; Vilcans, J.

    1970-01-01

    Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices.

  13. Restaurant food cooling practices.

    PubMed

    Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

    2012-12-01

    Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study.

  14. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Kees de Jager

    2004-08-01

    Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor.

  15. Compton Sources of Electromagnetic Radiation

    SciTech Connect

    Geoffrey Krafft,Gerd Priebe

    2011-01-01

    When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

  16. Electromagnetically Clean Solar Arrays

    NASA Technical Reports Server (NTRS)

    Stem, Theodore G.; Kenniston, Anthony E.

    2008-01-01

    The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the

  17. Ultrafast electron transport in graphene and magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Turchinovich, Dmitry

    2016-03-01

    Ultrafast terahertz spectroscopy is an ideal tool for observation of dynamics of charge, lattice and spin in solids on the most elementary timescale: in the regime ωτ ~ 1, where ω is the electromagnetic wave oscillation frequency, and τ is the characteristic timescale at which the fundamental phenomena in the three subsystems comprising the solid occur. In this paper two case studies will be discussed. (i) Ultrafast electron transport in graphene. We will show, that the free-carrier conductivity of graphene in arbitrary ultrafast, (sub-)picosecond electric fields is defined by the thermodynamic balance maintained within the electronic structure of graphene acting as thermalized electron gas. Within this simple thermodynamic picture, the electron gas quasi-instantaneously increases its temperature by absorbing the energy of driving ultrafast electric field, and at the same time cools down via a time-retarded, few picosecond-long process of phonon emission. The asymmetry in electron heating and cooling dynamics leads to heat accumulation in the electron population of graphene, concomitantly lowering the chemical potential for hotter electrons, and thereby reducing the intraband conductivity of graphene - an effect crucially important for understanding of ultrafast graphene transistors and photodetectors. (ii) We will also discuss the fundamental observation of spin-controlled electron conduction of Fermilevel electrons in ferromagnetic metals, and will directly quantify the Mott picture of conduction in ferromagnets - the effect directly employed in modern magnetic sensor technologies such as giant magnetoresistance.

  18. Electromagnetic Radiation Analysis

    DTIC Science & Technology

    1978-04-10

    A methodology is given for determining whether electromagnetic radiation of sufficient strength to cause performance degradation to the test item...exists at the test item location. The results of an electromagnetic radiation effects test are used to identify the radio frequencies and electromagnetic ... radiation levels to which the test item is susceptible. Further, using a test bed, comparisons are made with the representative signal levels to

  19. Electron beam focusing system

    SciTech Connect

    Dikansky, N.; Nagaitsev, S.; Parkhomchuk, V.

    1997-09-01

    The high energy electron cooling requires a very cold electron beam. Thus, the electron beam focusing system is very important for the performance of electron cooling. A system with and without longitudinal magnetic field is presented for discussion. Interaction of electron beam with the vacuum chamber as well as with the background ions and stored antiprotons can cause the coherent electron beam instabilities. Focusing system requirements needed to suppress these instabilities are presented.

  20. Excitation of high-frequency electromagnetic waves by energetic electrons with a loss cone distribution in a field-aligned potential drop

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.; Vinas, Adolfo F.

    1994-01-01

    The electron cyclotron maser instability (CMI) driven by momentum space anisotropy (df/dp (sub perpendicular) greater than 0) has been invoked to explain many aspects, such as the modes of propagation, harmonic emissions, and the source characteristics of the auroral kilometric radiation (AKR). Recent satellite observations of AKR sources indicate that the source regions are often imbedded within the auroral acceleration region characterized by the presence of a field-aligned potential drop. In this paper we investigate the excitation of the fundamental extraordinary mode radiation due to the accelerated electrons. The momentum space distribution of these energetic electrons is modeled by a realistic upward loss cone as modified by the presence of a parallel potential drop below the observation point. On the basis of linear growth rate calculations we present the emission characteristics, such as the frequency spectrum and the emission angular distribution as functions of the plasma parameters. We will discuss the implication of our results on the generation of the AKR from the edges of the auroral density cavities.