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1

Thermal transport: Cool electronics  

NASA Astrophysics Data System (ADS)

Although heat removal in electronics at room temperature is typically governed by a hierarchy of conduction and convection phenomena, heat dissipation in cryogenic electronics can face a fundamental limit analogous to that of black-body emission of electromagnetic radiation.

Cho, Jungwan; Goodson, Kenneth E.

2015-02-01

2

Water-cooled electronics  

Microsoft Academic Search

LHC experiments demand on cooling of electronic instrumentation will be extremely high. A large number of racks will be located in underground caverns and counting rooms, where cooling by conventional climatisation would be prohibitively expensive. A series of tests on the direct water cooling of VMEbus units and of their standard power supplies is reported. A maximum dissipation of 60W

G. Dumont; Ph. Fontaine Vive Roux; B. Righini

2000-01-01

3

ElectronicsCooling  

NSDL National Science Digital Library

An important concern facing electronics designers is heat dissipation. Especially in laptop computers and server farms, overheating can be a major problem. ElectronicsCooling is a free, quarterly publication that provides "practical information to the reader that relates to cooling of today's electronics." Every article since the magazine's debut in 1995 can be viewed from this site. Common topics are packaging, thermal design, and technical data related to many types of electronics. Contributions to ElectronicsCooling are generally from industry and academia.

2002-01-01

4

Coherent Electron Cooling  

SciTech Connect

Cooling intense high-energy hadron beams poses a major challenge for modern accelerator physics. The synchrotron radiation emitted from such beams is feeble; even in the Large Hadron Collider (LHC) operating with 7 TeV protons, the longitudinal damping time is about 13 hours. None of the traditional cooling methods seem able to cool LHC-class protons beams. In this Letter, we present a novel method of coherent electron cooling based on a high-gain free-electron laser (FEL). This technique could be critical for reaching high luminosities in hadron and electron-hadron colliders.

Litvinenko, Vladimir N. [Brookhaven National Laboratory, Upton, Long Island, New York (United States); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia (United States)

2009-03-20

5

Computational Electronics and Electromagnetics  

SciTech Connect

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.

DeFord, J.F.

1993-03-01

6

Electron Cooling of RHIC  

SciTech Connect

We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

I. Ben-Zvi; D.S. Barton; D.B. Beavis; M. Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X.Y. Chang; R. Connolly; Yu.I. Eidelman; A.V. Fedotov; W. Fischer; D.M. Gassner; H. Hahn; M. Harrison; A. Hershcovitch; H.-C. Hseuh; A.K. Jain; P.D.J. Johnson; D. Kayran; J. Kewisch; R.F. Lambiase; V. Litvinenko; W.W. MacKay; G.J. Mahler; N. Malitsky; G.T. McIntyre; W. Meng; K.A.M. Mirabella; C. Montag; T.C.N. Nehring; T. Nicoletti; B. Oerter; G. Parzen; D. Pate; J. Rank; T. Rao; T. Roser; T. Russo; J. Scaduto; K. Smith; D. Trbojevic; G. Wang; J. Wei; N.W.W. Williams; K.-C. Wu; V. Yakimenko; A. Zaltsman; Y. Zhao; D.T. Abell; D.L. Bruhwiler; H. Bluem; A. Burger; M.D. Cole; A.J. Favale; D. Holmes; J. Rathke; T. Schultheiss; A.M.M. Todd; A.V. Burov; S. Nagaitsev; J.R. Delayen; Y.S. Derbenev; L. W. Funk; P. Kneisel; L. Merminga; H.L. Phillips; J.P. Preble; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; J.S. Sekutowicz

2005-05-16

7

Computational electronics and electromagnetics  

SciTech Connect

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.

Shang, C. C.

1997-02-01

8

Advanced Cooling for Power Electronics  

Microsoft Academic Search

Power electronics devices such as MOSFET's, GTO's, IGBT's, IGCT's etc. are now widely used to efficiently deliver electrical power in home electronics, industrial drives, telecommunication, transport, electric grid and numerous other applications. This paper discusses cooling technologies that have evolved in step to remove increasing levels of heat dissipation and manage junction temperatures to achieve goals for efficiency, cost, and

Sukhvinder S. Kang

2012-01-01

9

Enhancement of electromagnetically induced transparency cooling by an optical cavity  

NASA Astrophysics Data System (ADS)

We theoretically investigate an enhanced electromagnetically induced transparency (EIT) cooling method by introducing a high finesse cavity. We find that the quantum destructive interference that is induced by the EIT effect and the cavity coupling can eliminate all of the heating effects in the cooling process by choosing appropriate parameters. Compared with the EIT cooling scheme, a lower final temperature can be obtained under the same conditions in our scheme.

Zhang, Jie; Zhang, Shuo; Ou, Bao-Quan; Wu, Wei; Chen, Ping-Xing

2014-11-01

10

Energy Efficient Electronics Cooling Project  

SciTech Connect

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.

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

2012-02-17

11

Cooling Technology for Electronic Computers  

NASA Astrophysics Data System (ADS)

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.

Nakayama, Wataru

12

Improved cooling of electromagnetics by directed airflow  

NASA Astrophysics Data System (ADS)

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.

Fain, Adam Matthew

13

MEIC Electron Cooling Simulation Using Betacool  

SciTech Connect

Electron cooling of ion beams is the most critical R&D issue in Jefferson Lab's MEIC design. In the ion collider ring, a bunched electron beam driven by an energy-recovery SRF linac assisted by a circulate ring will be employed to cool protons or ions with energies up to 100 GeV/u, a parameter regime that electron cooling has never been applied. It is essential to understand how efficient the electron cooling is, particularly in the high energy range, to confirm the feasibility of the design. Electron cooling is also important in LEIC design although the ion energy is 25 GeV/u, lower than MEIC. In this paper, we will present first results of the simulation studies of electron cooling processes in the collider ring of both MEIC and LEIC using BETACOOL code.

Zhang, He [JLAB; Zhang, Yuhong [JLAB

2013-12-01

14

Intermediate Energy Electron Cooling for Antiproton Sources  

NASA Astrophysics Data System (ADS)

Electron cooling at low energies ((gamma) slightly greater than one) has been shown to be an extremely effective means to increase the phase space density of proton beams. This document starts with a review of the progress made in low energy electron cooling, followed by a brief look at the parameters of intermediate energy electron cooling. ((gamma) of five to ten). The results of an emittance measurement done on an electrostatic accelerator are presented indicating that such a device would be ideal for intermediate energy electron cooling. A complete electron optics design of the system is done next, solving the beam envelope evolution problem in the presence of emittance, space charge, and acceleration. Application of intermediate energy electron cooling to the Fermilab antiproton source is theoretically studied. The amount of time it takes for the antiproton beam to cool is calculated including the effects of finite electron beam temperature, betatron oscillations, and intrabeam scattering. A four ampere electron beam will cool the Fermilab antiproton beam in half an hour. Lastly, the final equilibrium antiproton emittances obtainable are estimated. Equilibrium between the competing processes of intrabeam scattering and electron cooling exists when the transverse antiproton beam emittances are 0.12 (pi) mm-mr and the longitudinal antiproton beam emittance is (DELTA)p/p = 1 x 10('-5). This represents a phase space density increase of about 15 in each transverse plane, and an improvement of 20 in the energy resolution of the accumulator. Possible instabilities of such a dense beam are investigated.

Larson, Delbert John

15

Direct Liquid Cooling for Electronic Equipment  

SciTech Connect

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 with data center energy use modeling software to estimate overall site energy use. These estimates show that an overall data center energy savings of approximately 20 percent can be expected if a center is retrofitted as specified in the models used. Increasing the portion of heat captured by this technology is an area suggested for further development.

Coles, Henry; Greenberg, Steve

2014-03-01

16

Simulation study of electron response amplification in coherent electron cooling  

SciTech Connect

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.

Hao Y.; Litvinenko, V.N.

2012-05-20

17

Classical electromagnetic radiation of the Dirac electron  

NASA Technical Reports Server (NTRS)

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.

Lanyi, G.

1973-01-01

18

Electronics Cooling Fan Noise Prediction  

Microsoft Academic Search

Using the finite volume CFD software FLUENT, one fan was studied at a given flow rate (1.5m3\\/min) for three different operational rotating speeds : 2,000, 2,350 and 2,700 rpm. The turbulent air flow analysis predicts the acoustic behavior of the fan. The best fan operating window, i.e. the one giving the best ratio between noise emissions and cooling performance, can

Antoine Dozolme; Hossam Metwally; Thierry Marchal

2007-01-01

19

Application of refrigeration system in electronics cooling  

Microsoft Academic Search

An experimental investigation of the transient response of the vapor compression refrigeration (VCR) system to rapid change in evaporator (simulated electronics) heat load is presented. In this study, the VCR system is designed and constructed specifically for applications to cool high heat flux electronics and high-end computers. Temperature and pressure data were measured at pre-selected locations to study the behavior

A. G. Agwu Nnanna

2006-01-01

20

Power electronics substrate for direct substrate cooling  

DOEpatents

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.

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

21

Methods and apparatus for cooling electronics  

DOEpatents

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.

Hall, Shawn Anthony; Kopcsay, Gerard Vincent

2014-12-02

22

Single Pass Electron Cooling Simulations for MEIC  

SciTech Connect

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.

Bell, G. I. [Tech-X Corp.; Pogorelov, I. V. [Tech-X Corp.; Schwartz, B. T. [Tech-X Corp.; Zhang, Yuhong [JLAB; Zhang, He [JLAB

2013-12-01

23

Method of fabricating a cooled electronic system  

DOEpatents

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.

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

24

Thermoelectric Devices Cool, Power Electronics  

NASA Technical Reports Server (NTRS)

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.

2009-01-01

25

Thermoelectric cooler application in electronic cooling  

Microsoft Academic Search

This study addresses thermoelectric cooler (TEC) applications in the electronic cooling. The cold side temperature (Tc) and temperature difference between TEC cold and hot sides (?T=Th?Tc, Th=temperature of hot side of TEC) were used as the parameters. The cooling capacity, junction temperature, coefficient of performance (COP) of TEC and the required heat sink thermal resistance at the TEC hot side

Reiyu Chein; Guanming Huang

2004-01-01

26

Direct-Cooled Power Electronics Substrate  

SciTech Connect

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.

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

2008-12-23

27

Electromagnetic drift modes in an inhomogeneous electron gas  

Microsoft Academic Search

A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices.

P. K. Shukla; H. L. Pécseli; J. Juul Rasmussen

1986-01-01

28

FREE ELECTRON LASERS AND HIGH-ENERGY ELECTRON COOLING.  

SciTech Connect

Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation of such beams is too feeble to provide significant cooling: even in the Large Hadron Collider (LHC) with 7 TeV protons, the longitudinal damping time is about thirteen hours. Decrements of traditional electron cooling decrease rapidly as the high power of beam energy, and an effective electron cooling of protons or antiprotons at energies above 100 GeV seems unlikely. Traditional stochastic cooling still cannot catch up with the challenge of cooling high-intensity bunched proton beams--to be effective, its bandwidth must be increased by about two orders-of-magnitude. Two techniques offering the potential to cool high-energy hadron beams are optical stochastic cooling (OSC) and coherent electron cooling (CEC)--the latter is the focus of this paper. In the early 1980s, CEC was suggested as a possibility for using various instabilities in an electron beam to enhance its interaction with hadrons (i.e., cooling them). The capabilities of present-day accelerator technology, Energy Recovery Linacs (ERLs), and high-gain Free-Electron Lasers (FELs), finally caught up with the idea and provided the all necessary ingredients for realizing such a process. In this paper, we discuss the principles, and the main limitations of the CEC process based on a high-gain FEL driven by an ERL. We also present, and summarize in Table 1, some numerical examples of CEC for ions and protons in RHIC and the LHC.

LITVINENKO,V.N.

2007-08-31

29

Cooling of electronics in collider experiments  

SciTech Connect

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.

Richard P. Stanek et al.

2003-11-07

30

Potential Refrigerants for Power Electronics Cooling  

SciTech Connect

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.

Starke, M.R.

2005-10-24

31

Influence of electron beam parameters on coherent electron cooling  

SciTech Connect

Coherent electron cooling (CeC) promises to revolutionize the cooling of high energy hadron beams. The intricate dynamics of the CeC depends both on the local density and energy distribution of the beam. The variations of the local density (beam current) are inevitable in any realistic beam. Hence, in this paper we propose a novel method of beam conditioning. The conditioning provides compensation of effect from such variation by a correlated energy modulation. We use our analytical FEL model for an electron bunch with Gaussian line charge density and cosine-type energy variation along bunch. We analyze the phase variation between the electron density modulation at the exit of the FEL-amplifier and the ions inducing it in the modulator as a function of the peak current and the electron beam energy. Based on this analysis, electron bunch parameters for optimal CeC cooling are found numerically.

Wang G.; Hao, Y.; Litvinenko, V.N.; Webb, S.

2012-05-20

32

Cooling an electron gas using quantum dot based electronic refrigeration  

E-print Network

and theoretical investigation of a re- frigeration scheme that has the potential to cool 2DEGs below the temperatures currently available. Cooling to ever lower temperatures would be beneficial for studying fragile fractional quantum Hall states, non-Fermi-liquid... dots. Conventionally, low temperature measurements of 2DEGs are made by cooling the sample to 1.5 K with liquid Helium-4, to 300 mK with liquid Helium-3, or even down to a few mK using a dilution refrigerator. However, at lower temperatures the electron...

Prance, Jonathan Robert

2009-10-13

33

Thermal management of high power dissipation electronic packages: from air cooling to liquid cooling  

Microsoft Academic Search

Performance-driven electronic packaging demands for thermal solutions of high power dissipation such as enhanced air cooling or, alternatively, liquid cooling technologies. This paper reports the characterization of air-cooled vapor chamber heat sink (VCHS) and liquid cooled heat sinks (LCHS) for electronic packages with a targeted power dissipation of 140W. The test vehicle flip chip plastic BGA package (FC-PBGA) involves a

H. Y. Zhang; D. Pinjala; Poi-Siong Teo

2003-01-01

34

Measurement for electromagnetic susceptibility of the electronic medical equipment  

Microsoft Academic Search

In this paper, the electromagnetic immunity of electronic medical equipment was tested by employing a standard test method for medical equipment. In addition, the electromagnetic interference to the medical equipment caused by two different types of portable transceiver, have been studied. In this study, 20 pieces of medical equipment of 14 different types were investigated. They are a patient monitor,

Han-Kil Bae; Jong-Heon Kim

1999-01-01

35

Electromagnetically-induced-transparency-like ground-state cooling in a double-cavity optomechanical system  

NASA Astrophysics Data System (ADS)

We propose to cool a mechanical resonator close to its ground state via an electromagnetically-induced-transparency (EIT)-like cooling mechanism in a double-cavity optomechanical system, where an additional cavity couples to the original one in the standard optomechanical system. By choosing optimal parameters such that the cooling process of the mechanical resonator corresponds to the maximum value of the optical fluctuation spectrum and the heating process to the minimum one, the mechanical resonator can be cooled with the final mean phonon number less than that at the absence of the additional cavity. And we show the mechanical resonator may be cooled close to its ground state via such an EIT-like cooling mechanism even when the original resolved sideband condition is not fulfilled.

Guo, Yujie; Li, Kai; Nie, Wenjie; Li, Yong

2014-11-01

36

Simulation and Modeling Techniques for Signal Integrity and Electromagnetic Interference on High Frequency Electronic Systems.  

E-print Network

Simulation and Modeling Techniques for Signal Integrity and Electromagnetic Interference on High and Modeling Techniques for Signal Integrity and Electromagnetic Interference on High Frequency Electronic Integrity and Electromagnetic Interference on High Frequency Electronic Systems. by Luca Daniel Doctor

Daniel, Luca

37

Electromagnetic and thermal models of a water-cooled dipole radiating in a biological tissue  

Microsoft Academic Search

An insulated, water-cooled dipole, radiating in a biological tissue, is analyzed with a theoretical electromagnetic and thermal model. The SAR (specific absorption rate) and temperature distributions are calculated taking into account the effect of the water flowing inside the applicator. The steady-state temperatures in a dissipative medium, interacting with the dipole, are evaluated for several thicknesses of the external casing,

Guido Biffi Gentili; M. Leoncini; F. Gori

1991-01-01

38

Superconducting platinum silicide for electron cooling in silicon  

NASA Astrophysics Data System (ADS)

We demonstrate electron cooling in silicon using platinum silicide as a superconductor contact to selectively remove the highest energy electrons. The superconducting critical temperature of bulk PtSi is reduced from around 1 K to 0.79 K by using a thin film (10 nm) of PtSi, which enhances cooling performance at lower temperatures. We use an electron cooling model to infer that electrons in silicon are cooled from 100 mK to 50 mK in such a device.

Prest, M. J.; Richardson-Bullock, J. S.; Zhao, Q. T.; Muhonen, J. T.; Gunnarsson, D.; Prunnila, M.; Shah, V. A.; Whall, T. E.; Parker, E. H. C.; Leadley, D. R.

2015-01-01

39

A Fluid-kinetic Hybrid Electron Model for Electromagnetic Simulations  

SciTech Connect

A fluid-kinetic hybrid electron model for electromagnetic simulations of finite-beta plasmas is developed based on an expansion of the electron response using the electron-ion mass ratio as a small parameter (Here beta is the ratio of plasma pressure to magnetic pressure.) The model accurately recovers low-frequency plasma dielectric responses and faithfully preserves nonlinear kinetic effects (e.g., phase space trapping). Maximum numerical efficiency is achieved by overcoming the electron Courant condition and suppressing high-frequency modes. This method is most useful for nonlinear kinetic (particle-in-cell or Vlasov) simulations of electromagnetic microturbulence and Alfvenic instabilities in magnetized plasmas.

Zhihong Lin; Liu Chen

2001-01-30

40

Field measurements in the Fermilab electron cooling solenoid prototype  

SciTech Connect

To increase the Tevatron luminosity, Fermilab is developing a high-energy electron cooling system [1] to cool 8.9-GeV/c antiprotons in the Recycler ring. The schematic layout of the Recycler Electron Cooling (REC) system is shown in Figure 1. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through a cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 10{sup -4} rad, the cooling section will be immersed into a solenoidal field of 50-150G. As part of the R&D effort, a cooling section prototype consisting of 9 modules (90% of the total length of a future section) was assembled and measured. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of solenoid prototype field measurements. The design of the cooling section solenoid is discussed in Chapter 2. Chapter 3 describes details of a dedicated measurement system, capable of measuring small transverse field components, while the system's measurement errors are analyzed in Chapter 4. Chapter 5 contains measured field distributions of individual elements of the cooling section as well as an evaluation of the magnetic shielding efficiency. An algorithm of field adjustments for providing lowest possible electron trajectory perturbations is proposed in Chapter 6; also, this chapter shows the results of our first attempts of implementing the algorithm.

A. C. Crawford et al.

2003-10-02

41

Progress with FEL-based coherent electron cooling  

SciTech Connect

Cooling intense high-energy hadron beams remains a major challenge for accelerator physics. Synchrotron radiation is too feeble, while efficiency of two other cooling methods falls rapidly either at high bunch intensities (i.e. stochastic cooling of protons) or at high energies (i.e. e-cooling). The possibility of coherent electron cooling, based on high-gain FEL and ERL, was presented at last FEL conference [1]. This scheme promises significant increases in luminosities of modern high-energy hadron and electron-hadron colliders, such as LHC and eRHIC. In this paper we report progress made in the past year on the development of this scheme of coherent electron cooling (CeC), results of analytical and numerical evaluation of the concept as well our prediction for LHC and RHIC. We also present layout for proof-of-principle experiment at RHIC using our R&D ERL which is under construction.

Litvinenko,V.; Ben-Zvi, I.; Blaskiewicz, M.; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G.; Bell, G.; Bruhwiler, D.; Sobol, A.; Shevchenko, O.; Vinokurov, N.A.; Derbenev, Y.; Reiche, S.

2008-08-24

42

Cooling at the quantum limit and RF refrigeration  

E-print Network

31 (2002) #12;Electromagnetic transfer of heat (photons) Lattice Electrical environment Electron (electromagnetic) heat transport Cooling at the quantum limit: experiments RF refrigeration in a single;Conclusions Electromagnetic thermal coupling becomes important in small circuits at very low temperatures

Fominov, Yakov

43

Shear electromagnetic waves in strongly magnetized quantum electron positron plasmas  

Microsoft Academic Search

We study the dispersion properties of low-frequency (in comparison with the electron\\/positron gyrofrequency) shear electromagnetic waves in an ultra-cold quantum magnetoplasma composed of electrons and positrons. By using the electron and positron fluid velocities deduced from the quantum momentum equations, together with the continuity equations and Ampère's law, we derive the governing equation for the shear waves. This equation is

P. K. Shukla; L. Stenflo

2006-01-01

44

Advanced cooling techniques for FASTBUS electronics  

SciTech Connect

A multi-phase research and development effort has been conducted to explore improved cooling techniques for the FASTBUS system. The research was supported by the Fermi National Accelerator Laboratory. Some of the relevant, major requirements and limits of this system are: 1. The cooling system should not significantly interfere with the rapid handling of the cards; 2. The die temperatures of the integrated circuits should not exceed 85/sup 0/C; 3. The temperature differential between the dies of emitter coupled logic (ECL) circuits that connect directly to each other should not exceed 30/sup 0/C; 4. The temperature differential of the cooling air between any two points in the module should not exceed 20/sup 0/C; 5. In air cooled modules, the air temperature should not exceed 60/sup 0/C anywhere; and 6. The noise emanating from the computer should be at a tolerable level. The first requirement, together with some related considerations, virtually excludes any direct liquid cooling schemes. Thus heat removal from the chips themselves can be achieved either by convection to air or by a heat conducting structure which transfers the heat to the coolant used. The second through fourth requirements are generally rigorous. However, the fifth is for plastic encased microchips (CA3083 16-pin, high current transistor, dual in-line package) and can be relaxed for other types with lower internal thermal resistances. Our work can be divided into three parts. The first dealt with the development of an air cooled system based on the state-of-the-art of commercially available technology. The second explored various air cooling techniques and the third, examined methods where the heat from the chips was conducted to water cooled plates located parallel to the chip carrying cards.

Chato, J.C.; Golliher, E.L.; Downing, R.W.

1986-02-01

45

Absorption of electromagnetic radiation by semimetal electrons  

SciTech Connect

This paper investigates cyclotron photon resonance in textured bismuth where the electron energy in the conduction band is determined by an expression (presented), using perturbation theory methods. It is shown that the electron dispersion law, not being quadratic, results in spin splitting of the resonance peaks.

Sigachev, A.F.

1986-06-01

46

Cooling structure for EMC shielded high frequency electronics  

Microsoft Academic Search

Cooling of electronics is normally achieved using air passing through apertures in the enclosure; as a result the shielding effectiveness of the shielded enclosure is reduced. In this paper, the design of a new cooling structure and its evaluation in a wind tunnel is presented. The developed design presented here is a double heat sink in extruded aluminum. Into one

W. Peter Siebert

2006-01-01

47

Ground-state cooling for a trapped atom using cavity-induced double electromagnetically induced transparency.  

PubMed

We propose a cooling scheme for a trapped atom using the phenomenon of cavity-induced double electromagnetically induced transparency (EIT), where the atom comprising of four levels in tripod configuration is confined inside a high-finesse optical cavity. By exploiting one cavity-induced EIT, which involves one cavity photon and two laser photons, carrier transition can be eliminated due to the quantum destructive interference of excitation paths. Heating process originated from blue-sideband transition mediated by cavity field can also be prohibited due to the destructive quantum interference with the additional transition between the additional ground state and the excited state. As a consequence, the trapped atom can be cooled to the motional ground state in the leading order of the Lamb-Dicke parameters. In addition, the cooling rate is of the same order of magnitude as that obtained in the cavity-induced single EIT scheme. PMID:23481803

Yi, Zhen; Gu, Wen-ju; Li, Gao-xiang

2013-02-11

48

Progress on Analytical Modeling of Coherent Electron Cooling  

SciTech Connect

We report recent progresses on analytical studies of Coherent Electron Cooling. The phase space electron beam distribution obtained from the 1D FEL amplifier is applied to an infinite electron plasma model and the electron density evolution inside the kicker is derived. We also investigate the velocity modulation in the modulator and obtain a closed form solution for the current density evolution for infinite homogeneous electron plasma.

Wang, G.; Blaskiewicz, M.; Litvinenko, V.; Webb, S.

2010-05-23

49

The interaction of electromagnetic radiation with one-electron atoms  

E-print Network

The interaction of electromagnetic radiation with one-electron atoms January 21, 2002 1 Introduction We examine the interactions of radiation with a hydrogen-like atom as a simple ex- ample by passing radiation), spontaneous emission (radiation without any external stimulus), and the continuum

Landstreet, John D.

50

Electromagnetic generation of electronically steered ultrasonic bulk waves  

Microsoft Academic Search

The frequency dependence of the propagation direction of ultrasonic shear and longitudinal waves generated by a meander-line electromagnetic transducer (EMAT) at MHz frequencies has been determined. The results are found to agree well with theory and demonstrate that electronic beam steering is possible using EMAT's. The relative efficiency of generation in aluminum was also studied and, for a specific meander-line

T. J. Moran; R. M. Panos

1976-01-01

51

Electromagnetic Interference Generated from Fast Switching Power Electronic Devices  

Microsoft Academic Search

This paper investigates the negative effects of electromagnetic interference (EMI) due to fast switching power devices (high dv\\/dt and di\\/dt) used in power electronic converters and industrial equipment. Mitigation techniques have been explored to reduce EMI noise effectively. Remedial measures to reduce the risk of equipment malfunction and health risk due to EMI have been explored. In this paper, EMI

K. M. Muttaqi; M. E. Haque

2008-01-01

52

On a Nonlocal Electromagnetic Model for Electron and Muon Masses  

Microsoft Academic Search

In a phenomenological way, a non-local electromagnetic interaction with a Pauli term is assumed in order to explain the whole masses of electron and muon. Qualitative discussions are devoted to the properties of form factors on the asumption of similar internal structures for both particles.

J. L. Ferreira; Yasuhisa Katayama

1960-01-01

53

Electromagnetic solitary pulses in a magnetized electron-positron plasma  

SciTech Connect

A theory for large amplitude compressional electromagnetic solitary pulses in a magnetized electron-positron (e-p) plasma is presented. The pulses, which propagate perpendicular to the external magnetic field, are associated with the compression of the plasma density and the wave magnetic field. Here the solitary wave magnetic field pressure provides the restoring force, while the inertia comes from the equal mass electrons and positrons. The solitary pulses are formed due to a balance between the compressional wave dispersion arising from the curl of the inertial forces in Faraday's law and the nonlinearities associated with the divergence of the electron and positron fluxes, the nonlinear Lorentz forces, the advection of the e-p fluids, and the nonlinear plasma current densities. The compressional solitary pulses can exist in a well-defined speed range above the Alfven speed. They can be associated with localized electromagnetic field excitations in magnetized laboratory and space plasmas composed of electrons and positrons.

Shukla, P. K. [RUB International Chair, International Centre for Advanced Studies in Physical Sciences, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Eliasson, B. [Institut fuer Theoretische Physik, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Stenflo, L. [Department of Physics, Linkoeping University, SE-58183 Linkoeping (Sweden)

2011-03-15

54

Two-Phase Spray Cooling of Hybrid Vehicle Electronics  

Microsoft Academic Search

As part of the U.S. Department of Energy's (DOE's) Power Electronics and Electric Machines Program area, the DOE's National Renewable Energy Laboratory (NREL) is currently leading a national effort to develop next-generation cooling technologies for hybrid vehicle electronics. Spray cooling has been identified as a potential solution that can dissipate 150-200 W\\/cm2 while maintaining the chip temperature below 125degC. This

Issam Mudawar; Desikan Bharathan; Kenneth Kelly; Sreekant Narumanchi

2009-01-01

55

HIGH-CURRENT ERL-BASED ELECTRON COOLING FOR RHIC.  

SciTech Connect

The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R&D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC.

BEN-ZVI, I.

2005-09-18

56

Nonlinear Electromagnetic Response of a Uniform Electron Gas  

NASA Astrophysics Data System (ADS)

The linear electromagnetic response of a uniform electron gas to a longitudinal electric field is determined, within the self-consistent-field theory, by the linear polarizability and the Lindhard dielectric function. Using the same approach, we derive analytical expressions for the second- and third-order nonlinear polarizabilities of the three-, two-, and one-dimensional homogeneous electron gases with the parabolic electron energy dispersion. The results are valid both for degenerate (Fermi) and nondegenerate (Boltzmann) electron gases. A resonant enhancement of the second- and third-harmonics generation due to a combination of the single-particle and collective (plasma) resonances is predicted.

Mikhailov, S. A.

2014-07-01

57

Cooling of hot electrons in amorphous silicon  

SciTech Connect

Measurements of the cooling rate of hot carriers in amorphous silicon are made with a two-pump, one-probe technique. The experiment is simulated with a rate-equation model describing the energy transfer between a population of hot carriers and the lattice. An energy transfer rate proportional to the temperature difference is found to be consistent with the experimental data while an energy transfer independent of the temperature difference is not. This contrasts with the situation in crystalline silicon. The measured cooling rates are sufficient to explain the difficulty in observing avalanche effects in amorphous silicon.

Vanderhaghen, R.; Hulin, D.; Cuzeau, S.; White, J.O.

1997-07-01

58

Coherent electron cooling proof of principle instrumentation design  

SciTech Connect

The goal of the Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment being designed at RHIC is to demonstrate longitudinal (energy spread) cooling before the expected CD-2 for eRHIC. The scope of the experiment is to longitudinally cool a single bunch of 40 GeV/u gold ions in RHIC. This paper will describe the instrumentation systems proposed to meet the diagnostics challenges. These include measurements of beam intensity, emittance, energy spread, bunch length, position, orbit stability, and transverse and temporal alignment of electron and ion beams.

Gassner D. M.; Litvinenko, V.; Michnoff, R.; Miller, T.; Minty, M.; Pinayev, I.

2012-04-15

59

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

Code of Federal Regulations, 2010 CFR

... 2010-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2010-10-01

60

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

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2011-10-01

61

Emerging Two-Phase Cooling Technologies for Power Electronic Inverters  

SciTech Connect

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 National Laboratory (ORNL) is leading the research on a novel floating refrigerant loop that cools high-power electronic devices and the motor/generator with very low cooling energy. The loop can be operated independently or attached to the air conditioning system of the vehicle to share the condenser and other mutually needed components. The ability to achieve low cooling energy in the floating loop is attributable to the liquid refrigerant operating at its hot saturated temperature (around 50 C+). In an air conditioning system, the liquid refrigerant is sub-cooled for producing cool air to the passenger compartment. The ORNL floating loop avoids the sub-cooling of the liquid refrigerant and saves significant cooling energy. It can raise the coefficient of performance (COP) more than 10 fold from that of the existing air-conditioning system, where the COP is the ratio of the cooled power and the input power for dissipating the cooled power. In order to thoroughly investigate emerging two-phase cooling technologies, ORNL subcontracted three university/companies to look into three leading two-phase cooling technologies. ORNL's assessments on these technologies are summarized in Section I. Detailed descriptions of the reports by the three university/companies (subcontractors) are in Section II.

Hsu, J.S.

2005-08-17

62

Electron beam injection during active experiments. I - Electromagnetic wave emissions  

NASA Technical Reports Server (NTRS)

The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

Winglee, R. M.; Kellogg, P. J.

1990-01-01

63

Relativistic electromagnetic waves in an electron-ion plasma  

NASA Astrophysics Data System (ADS)

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.

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

1987-09-01

64

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

SciTech Connect

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.

Fauquembergue, M.; Riou, J-F.; Guerin, W.; Rangwala, S.; Moron, F.; Villing, A.; Le Coq, Y.; Bouyer, P.; Aspect, A.; Lecrivain, M. [Groupe d'Optique Atomique, Laboratoire Charles Fabry de l'Institut d'Optique, Unite Mixte de Recherche (UMR) 8501 du Centre National de la Recherche Scientifique (CNRS), Batiment 503 Campus Universitaire d'Orsay, 91403 Orsay Cedex (France); Systemes et Applications des Technologies de l'Information et de Energie - SATIE, Laboratoire de l'Ecole Normale Superieure de Cachan, Unite Mixte de Recherche (UMR) 8029 du Centre National de la Recherche Scientifique (CNRS), 61, Avenue du President Wilson, 94235 Cachan Cedex (France)

2005-10-15

65

Effects of e-beam parameters on coherent electron cooling  

SciTech Connect

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.

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

2011-03-28

66

Atom-membrane cooling and entanglement using cavity electromagnetically induced transparency  

SciTech Connect

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.

Genes, Claudiu; Ritsch, Helmut [Institute for Theoretical Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck (Austria); Drewsen, Michael; Dantan, Aurelien [QUANTOP, Danish National Research Foundation Center for Quantum Optics, Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2011-11-15

67

Prospects for Doppler cooling of three-electronic-level molecules  

SciTech Connect

Analogous to the extension of laser cooling techniques from two-level to three-level atoms, Doppler cooling of molecules with an intermediate electronic state is considered. In particular, we use a rate-equation approach to simulate cooling of SiO{sup +}, in which population buildup in the intermediate state is prevented by its short lifetime. We determine that Doppler cooling of SiO{sup +} can be accomplished without optically repumping from the intermediate state, at the cost of causing undesirable parity flips and rotational diffusion. Since the necessary repumping would require a large number of continuous-wave lasers, optical pulse shaping of a femtosecond laser is proposed as an attractive alternative. Other candidate three-electron-level molecules are also discussed.

Nguyen, J. H. V.; Odom, B. [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States)

2011-05-15

68

Stability conditions for a neutralised electron cooling beam  

Microsoft Academic Search

Charge neutralisation of the cooling electron beam, e.g. by stationary ions produced from the residual gas, is desirable to compensate the space-charge induced velocity spread which tends to reduce the cooling force. However, it has been demonstrated by Parkhomchuk and collaborators (1993) that two-stream instabilities, especially transverse dipole modes, are a serious threat to the stability. In the present report

Jacques Bosser; S. Maury; D. Mohl; F. Varenne; I. Meshkov; E M Syresin; E. Mustafin; P R Zenkevich

1995-01-01

69

Electromagnetic generation of electronically steered ultrasonic bulk waves  

Microsoft Academic Search

The frequency dependence of the propagation direction of ultrasonic shear and longitudinal waves generated by a meander-line electromagnetic transducer (EMAT) at MHz frequencies has been determined. The results are found to agree well with theory and demonstrate that electronic beam steering is possible using EMAT’s. The relative efficiency of generation in aluminum was also studied and, for a specific meander-line

T. J. Moran; R. M. Panos

1976-01-01

70

Search for electron EDM with laser cooled radioactive atom  

NASA Astrophysics Data System (ADS)

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.

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

71

VORPAL SIMULATIONS RELEVANT TO COHERENT ELECTRON COOLING  

E-print Network

for simulating the modulator and kicker regions, where the electron and hadron beams will co). At the same time, hadrons experience longitudinal dispersion. 3. Kicker: The electric field induced, 6] is an ideal tool for investigating the mod- ulator and kicker stages. These stages are similar

72

Numerical Study of Electromagnetic ETG Turbulence: -dependence of Electron Heat Transport  

E-print Network

Numerical Study of Electromagnetic ETG Turbulence: -dependence of Electron Heat Transport B. Labit. To this end, we have developed a 3D toroidal global fluid code that solves a non-linear electromagnetic model, that magnetic fluctuations play an important role in electron transport [1]. Electromagnetic effects

73

Passive Two-Phase Cooling of Automotive Power Electronics: Preprint  

SciTech Connect

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.

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

2014-08-01

74

A uniform temperature heat sink for cooling of electronic devices  

Microsoft Academic Search

Experimental investigation of a heat sink for cooling of electronic devices is performed. The objective is to keep the operating temperature at a relatively low level of about 323–333 K, using a dielectric liquid that boils at a lower temperature, while reducing the undesired temperature variation in the both streamwise and transverse directions. The experimental study is based on systematic

G. Hetsroni; A. Mosyak; Z. Segal; G. Ziskind

2002-01-01

75

Evolution of cooling technology for electrical, electronic, and microelectronic equipment  

Microsoft Academic Search

Selected aspects of cooling technology for electrical apparatus and electronic devices are considered for the past 80 years. The emphasis is on the past 50 years. The technology has evolved to meet the challenges of microminiaturization, and heat transfer considerations are now an integral part of the design procedure for microelectronic systems.

Arthur E. Bergles

2003-01-01

76

Miniature Vapor Compressor Refrigeration System for Electronic Cooling  

Microsoft Academic Search

This paper experimentally investigated the thermal performance of a miniature vapor compressor refrigeration system using a thermal resistance model for electronic cooling. The evaporator, compressor, expansion valve, and condenser are the four main devices forming the refrigeration system with R-134a as a working fluid. The experimental parameters considered were the openings of the expansion valve and input heating power. The

Chih-Chung Chang; Nai-Wen Liang; Sih-Li Chen

2010-01-01

77

Cooling of ions and antiprotons with magnetized electrons  

NASA Astrophysics Data System (ADS)

Electron cooling is a well-established method to improve the phase space quality of ion beams in storage rings. More recently antiprotons have been cooled in traps, first by electrons and then by positrons in order to produce antihydrogen atoms as simplest form of antimatter for CPT-tests. During these cooling processes the light particles are guided by strong external magnetic fields which imposes a challenge to the theoretical description. Within the binary collision model we treat the Coulomb interaction as second-order perturbation to the helix motion of the light particles and also by numerical simulations. In the complementary dielectric theory we calculate the polarization of the light particles by solving the nonlinear Vlasov-Poisson equation as well as linear response. It turns out that the linearization becomes dubious at low ion velocities. In the presence of a strong magnetic field the numerically expensive solution of the Vlasov-Poisson equation is the method of choice, alternatively one may employ the binary collision model. Within this approach simulations must be employed for a repulsive interaction, e.g. antiproton-electron, or for highly charged ions. Drag forces F? are given as functions of the ion velocity v?i and can be used as input for codes to calculate cooling times.

Möllers, B.; Toepffer, C.; Walter, M.; Zwicknagel, G.; Carli, C.; Nersisyan, H.

2004-10-01

78

Electron Cooling and Debye-Waller Effect in Photoexcited Bismuth  

NASA Astrophysics Data System (ADS)

By means of first principles calculations, we compute the effective electron-phonon coupling constant G0 governing the electron cooling in photoexcited bismuth. G0 strongly increases as a function of electron temperature, which can be traced back to the semimetallic nature of bismuth. We also use a thermodynamical model to compute the time evolution of both electron and lattice temperatures following laser excitation. Thereby, we simulate the time evolution of (1 -1 0), (-2 1 1) and (2 -2 0) Bragg peak intensities measured by Sciaini et al. [Nature (London) 458, 56 (2009)NATUAS0028-0836] in femtosecond electron diffraction experiments. The effect of the electron temperature on the Debye-Waller factors through the softening of all optical modes across the whole Brillouin zone turns out to be crucial to reproduce the time evolution of these Bragg peak intensities.

Arnaud, B.; Giret, Y.

2013-01-01

79

Classical "Dressing" of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald  

E-print Network

densities of the fields of a free electron in a plane electromagnetic wave include interference termsClassical "Dressing" of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald Joseph the interference between the driving wave and the static part of the electron's field. The interference between

McDonald, Kirk

80

Classical ``Dressing'' of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald  

E-print Network

densities of the fields of a free electron in a plane electromagnetic wave include interference termsClassical ``Dressing'' of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald Joseph the interference between the driving wave and the static part of the electron's field. The interference between

McDonald, Kirk

81

Application of thermoelectric cooling to electronic equipment: a review and analysis  

Microsoft Academic Search

This paper provides a review of thermoelectric cooling and its application to the cooling of electronic equipment. A background discussion of thermoelectric cooling is provided briefly citing early history, current developments, and the defining thermoelectric heat pumping equations. Several examples are provided of early IBM applications of thermoelectric cooling. An analysis to assess thermoelectric cooling enhancement in terms of increases

R. E. Simons; R. C. Chu

2000-01-01

82

Ultrarelativistic electron states in a general background electromagnetic field  

E-print Network

The feasibility of obtaining exact analytical results in the realm of QED in the presence of a background electromagnetic field is almost exclusively limited to a few tractable cases, where the Dirac equation in the corresponding background field can be solved analytically. This circumstance has restricted, in particular, the theoretical analysis of QED processes in intense laser fields to within the plane-wave approximation even at those high intensities, achievable experimentally only by tightly focusing the laser energy in space. Here, within the Wentzel-Kramers-Brillouin (WKB) or eikonal approximation, we construct analytically single-particle electron states in the presence of a background electromagnetic field of general space-time structure in the realistic assumption that the initial energy of the electron is the largest dynamical energy scale in the problem. The relatively compact expression of these states opens, in particular, the possibility of investigating analytically strong-field QED processes in the presence of spatially focused laser beams, which is of particular relevance in view of the upcoming experimental campaigns in this field.

A. Di Piazza

2014-07-27

83

Verification of electromagnetic fluid-kinetic hybrid electron model in global gyrokinetic particle simulation  

E-print Network

Verification of electromagnetic fluid-kinetic hybrid electron model in global gyrokinetic particle electromagnetic drift-Alfvenic instabilities in tokamak. In particular, we have recovered the b the finite-b effects in order to properly study the turbulent transport in burning plasmas. Electromagnetic

Lin, Zhihong

84

Cryogenic heat pipe for cooling high temperature superconductors with application to Electromagnetic Formation Flight Satellites .  

E-print Network

??An emerging method of propellant-less formation flight propulsion is the use of electromagnets coupled with reaction wheels. This technique is called Electromagnetic Formation Flight (EMFF).… (more)

Kwon, Daniel W., 1980-

2009-01-01

85

A Project for synchrotron with electron cooling for cancer therapy  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

86

Low Frequency Electromagnetic Background Radiation From Electron Acceleration Above Thunderclouds  

NASA Astrophysics Data System (ADS)

It was recently proposed that the acceleration of electrons during the growth and branching of streamers above thunderclouds initiated by intense lightning discharges could result in detectable low frequency electromagnetic radiation from several tens of kHz up to several hundreds of kHz (Qin et al., GRL, 2012). The intensity of the predicted radiation scales with the streamer density which is particularly large during spectacular sprite occurrences such as jellyfish sprites and/or dancing sprites. Dancing sprites are up to one second long sequences of consecutive sprites or sprite groups which are typically separated by some hundreds of milliseconds and which tend to follow the spatial development of large scale intracloud lightning discharges. A particularly spectacular series of 10 dancing sprite events over a Mediterranean mesoscale convective system was recorded with a low light video camera in south-eastern France during the early morning hours of August 31, 2012. Each dancing sprite event was composed of ~3-4 consecutive sprites or groups of sprites. All of these sprite occurrences were associated with a sudden enhancement ~2 uV/m/Hz-1/2 of the low frequency electromagnetic background radiation as measured with a radio receiver in south-west England. It is estimated that ~1000 streamers at a height of ~40 km are necessary to epxlain the observed electric field strengths. These sudden enhancements are superimposed on a more continuous low frequency electromagnetic background radiation which accompanies each dancing sprite event. It is speculated that this low frequency 'radio glow' results from filamentary streamers near the cloud top as a result of the large scale electrostatic charging of the thundercloud and that it may be used as an indicator for sprite occurrences in future studies.

Fullekrug, Martin; Mezentsev, Andrew; Soula, Serge; van der Velde, Oscar; Farges, Thomas

2013-04-01

87

Influence of electron evaporative cooling on ultracold plasma expansion  

SciTech Connect

The expansion of ultracold neutral plasmas (UCP) is driven primarily by the thermal pressure of the electron component and is therefore sensitive to the electron temperature. For typical UCP spatial extents, evaporative cooling has a significant influence on the UCP expansion rate at lower densities (less than 10{sup 8}/cm{sup 3}). We studied the effect of electron evaporation in this density range. Owing to the low density, the effects of three-body recombination were negligible. We modeled the expansion by taking into account the change in electron temperature owing to evaporation as well as adiabatic expansion and found good agreement with our data. We also developed a simple model for initial evaporation over a range of ultracold plasma densities, sizes, and electron temperatures to determine over what parameter range electron evaporation is expected to have a significant effect. We also report on a signal calibration technique, which relates the signal at our detector to the total number of ions and electrons in the ultracold plasma.

Wilson, Truman; Chen, Wei-Ting; Roberts, Jacob [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)] [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)

2013-07-15

88

SIMULATIONS OF RHIC COHERENT STABILITIES DUE TO WAKEFIELD AND ELECTRON COOLING  

SciTech Connect

The Electron cooling beam has both coherent and incoherent effects to the circulating ion beam. The incoherent longitudinal cooling could reduce the ion beam energy spread and hence cause 'over-cooling' of the ion beam. Depending on the beam densities and cooling length, the coherent interaction between the ion and electron beam could either damp or anti-damp the ion coherent motions. Using the tracking codes, TRANFT, the threshold for 'over-cooling' has been found and compared with theoretical estimation. The transverse coherent effect of electron cooling has been implemented into the codes and its effect for the bunched ion beam is shown.

WANG,G.; BLASKIEWICZ, M.

2007-06-25

89

The interference of electronic implants in low frequency electromagnetic fields.  

PubMed

Electronic implants such as cardiac pacemakers or nerve stimulators can be impaired in different ways by amplitude-modulated and even continuous electric or magnetic fields of strong field intensities. For the implant bearer, possible consequences of a temporary electromagnetic interference may range from a harmless impairment of his well-being to a perilous predicament. Electromagnetic interferences in all types of implants cannot be covered here due to their various locations in the body and their different sensing systems. Therefore, this presentation focuses exemplarily on the most frequently used implant, the cardiac pacemaker. In case of an electromagnetic interference the cardiac pacemaker reacts by switching to inhibition mode or to fast asynchronous pacing. At a higher disturbance voltage on the input of the pacemaker, a regular asynchronous pacing is likely to arise. In particular, the first-named interference could be highly dangerous for the pacemaker patient. The interference threshold of cardiac pacemakers depends in a complex way on a number of different factors such as: electromagnetic immunity and adjustment of the pacemaker, the composition of the applied low-frequency fields (only electric or magnetic fields or combinations of both), their frequencies and modulations, the type of pacemaker system (bipolar, unipolar) and its location in the body, as well as the body size and orientation in the field, and last but not least, certain physiological conditions of the patient (e.g. inhalation, exhalation). In extensive laboratory studies we have investigated the interference mechanisms in more than 100 cardiac pacemakers (older types as well as current models) and the resulting worst-case conditions for pacemaker patients in low-frequency electric and magnetic fields. The verification of these results in different practical everyday-life situations, e.g. in the fields of high-voltage overhead lines or those of electronic article surveillance systems is currently in progress. In case of the vertically-oriented electric 50 Hz fields preliminary results show that per 1 kV/m unimpaired electrical field strength (rms) an interference voltage of about 400 microVpp as worst-case could occur at the input of a unipolar ventricularly controlled, left-pectorally implanted cardiac pacemaker. Thus, already a field strength above ca. 5 kV/m could cause an interference with an implanted pacemaker. The magnetic fields induces an electric disturbance voltage at the input of the pacemaker. The body and the pacemaker system compose several induction loops, whose induced voltages rates add or subtract. The effective area of one representing inductive loop ranges from 100 to 221 cm2. For the unfavourable left-pectorally implantated and atrially-controlled pacemaker with a low interference threshold, the interference threshold ranges between 552 and 16 microT (rms) for magnetic fields at frequencies between 10 and 250 Hz. On this basis the occurrence of interferences with implanted pacemakers is possible in everyday-life situations. But experiments demonstrate a low probability of interference of cardiac pacemakers in practical situations. This apparent contradiction can be explained by a very small band of inhibition in most pacemakers and, in comparison with the worst-case, deviating conditions. PMID:12741329

Silny, J

2003-04-01

90

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

PubMed

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. PMID:11802505

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

2001-12-17

91

A Comparative Study of Cooling of High Power Density Electronics Using Sprays and Microjets  

Microsoft Academic Search

Direct cooling by means of jets and sprays has been considered as a solution to the problem of cooling of high power density electronic devices. Although both methods are capable of very high heat removal rates no criterion exists that helps one decide as to which one is preferable, when designing a cooling system for electronic applications. In this work,

Matteo Fabbri; Shanjuan Jiang; Vijay K. Dhir

2005-01-01

92

Air Cooling for High Temperature Power Electronics (Presentation)  

SciTech Connect

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.

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

2014-09-01

93

Electromagnets  

NSDL National Science Digital Library

This is an activity about the properties of electromagnets, which is a crucial underpinning for understanding how magnetic fields are generated in nature, in the surface of the Sun, and in the interior of Earth. Learners will create an electromagnet by letting an electric current flow through a wire to generate a magnetic field, which is then detected using a compass. This activity requires a thin insulated wire, pencil, battery, compass and paper clips. This is Activity 2 of the Magnetism and Electromagnetism teachers guide.

94

Electromagnets  

NSDL National Science Digital Library

In this investigation, students will construct electromagnets and test to see which variables make them stronger. Although elementary and middle school teachers are expected to have done this activity with their classes, teachers of younger students often

Horton, Michael

2009-05-30

95

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

DOEpatents

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.

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

2014-12-16

96

Electron-ion collisions in strong electromagnetic fields: Quantum mechanical consideration  

NASA Astrophysics Data System (ADS)

The quantum problem of electron-ion scattering in strong electromagnetic fields is studied by numerical simulations. The scattering characteristics are found to agree well with those earlier obtained in the classical limit. The simulations demonstrate the bunching of electrons during electron-ion collisions, which indicates the possibility of generation of attosecond pulses in strong fields.

Serebryakov, D. A.; Balakin, A. A.; Fraiman, G. M.

2014-09-01

97

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

SciTech Connect

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.

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

2005-12-01

98

innovati nNREL Helps Cool the Power Electronics in Electric Vehicles  

E-print Network

innovati nNREL Helps Cool the Power Electronics in Electric Vehicles Researchers at the National for cooling power electronics devices in hybrid and electric vehicles. In collaboration with 3M and Wolverine vehicles. Widespread use of advanced electric-drive vehicles--including electric vehicles (EVs) and hybrid

99

REVIEWS OF TOPICAL PROBLEMS: Electron cooling and new possibilities in elementary particle physics  

Microsoft Academic Search

This review is devoted to a new method in experimental physics---electron cooling, which opens the possibility of storing intense and highly monochromatic beams of heavy particles and carrying out a wide range of experiments with high luminosity and resolution. The method is based on the cooling of beams by an accompanying electron flux as the result of Coulomb collisions of

G. I. Budker; Aleksandr N. Skrinskii

1978-01-01

100

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

SciTech Connect

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.

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

101

Electromagnets  

NSDL National Science Digital Library

In this activity, the students will complete the grand challenge and design an electromagnet to separate steel from aluminum for the recycler. In order to do this, students compare the induced magnetic field of an electric current with the magnetic field of a permanent magnet and must make the former look like the latter. They discover that looping the current produces the desired effect and find ways to further strengthen the magnetic field.

Vu Bioengineering Ret Program

102

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

SciTech Connect

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.

Timofeev, I. V.; Annenkov, V. V. [Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

2014-08-15

103

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

104

Heat Driven Cooling Of Portable Electronics Using Thermoelectric Technology  

Microsoft Academic Search

A novel ldquoshunt attachrdquo configuration for chip-scale thermoelectric (TE) generation of electric power from microprocessor waste heat is described, modeled, and parametrically analyzed. The generated electricity is used to drive a cooling fan that convectively cools the chip. A prototype using heat-driven cooling through off-the-shelf TE modules and a low-voltage fan was built and successfully applied to the thermal management

Gary L. Solbrekken; Kazuaki Yazawa; Avram Bar-Cohen

2008-01-01

105

Nonlinear Interactions between Electromagnetic Waves and Electron Plasma Oscillations in Quantum Plasmas  

Microsoft Academic Search

We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger

P. K. Shukla; B. Eliasson

2007-01-01

106

Electromagnetic instability and stopping power of plasma for relativistic electron beams  

Microsoft Academic Search

The stopping power of a plasma for a relativistic electron beam (REB) is derived by taking a Weibel-type electromagnetic instability into account in a collisionless plasma. A quasi-linear theory is developed to derive the stopping power of the plasma due to the electromagnetic instability. The wave-particle interaction by use of the renormalization theory leads to a saturation level of instability.

Toshio Okada; Keishiro Niu

1980-01-01

107

One-electron atoms in Schwarzschild Universe Bare and electromagnetically dressed cases  

E-print Network

The quantum mechanics of one-electron atoms in presence of external electromagnetic fields is considered within Weber's framework. The results by the earlier studies are extended in the sense that for given source and field configurations the changes of the electromagnetic potentials due to the curved background are included. The formulation is specialized to the case with Schwarzschild background. The first corrections to the energy levels for bare atom and Zeeman/Stark effects are calculated, exhibiting possible changes in meaningful orders.

Abolfazl Jafari

2014-02-11

108

One-electron atoms in Schwarzschild Universe Bare and electromagnetically dressed cases  

E-print Network

The quantum mechanics of one-electron atoms in presence of external electromagnetic fields is considered within Weber's framework. The results by the earlier studies are extended in the sense that for given source and field configurations the changes of the electromagnetic potentials due to the curved background are included. The formulation is specialized to the case with Schwarzschild background. The first corrections to the energy levels for bare atom and Zeeman/Stark effects are calculated, exhibiting possible changes in meaningful orders.

Jafari, Abolfazl

2014-01-01

109

IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-23, NO. 1, JANUARY 1987 103 Principles of Gyrotron Powered Electromagnetic  

E-print Network

Powered Electromagnetic Wieelers for Free-Electron Lasersvu B.G.DANLY, G. BEKEFI, R. C. DAVIDSON, R-power electromagnetic wiggler fields such as those produced by high-power gyrotrons is discussed. The use of short wavelength electromagnetic wigglers in waveguides and resonant cav- ities can significantly reduce required

Wurtele, Jonathan

110

A Silicon / Tungsten Electromagnetic Calorimeter with Integrated Electronics  

SciTech Connect

We discuss progress and issues relevant to the design of a highly segmented silicon-tungsten electromagnetic calorimeter. Our design features a complete readout chip which is integrated onto each detector wafer, thus reducing the effective channel count by a factor of about 1000. We apply this design to the SD detector of the American LC Physics Group, but some elements could be applicable elsewhere.

Frey, R

2004-12-16

111

Trapping of electrons in troughs of self generated electromagnetic standing waves in a bounded plasma column  

SciTech Connect

Observations and measurements are reported on electron trapping in troughs of self-generated electromagnetic standing waves in a bounded plasma column confined in a minimum-B field. The boundaries are smaller than the free space wavelength of the waves. Earlier work of researchers primarily focused upon electron localization effects induced by purely electrostatic perturbation. We demonstrate the possibility in the presence of electromagnetic standing waves generated in the bounded plasma column. The electron trapping is verified with electrostatic measurements of the plasma floating potential, electromagnetic measurements of the wave field profile, and optical intensity measurements of Argon ionic line at 488?nm. The experimental results show a reasonably good agreement with predictions of a Monte Carlo simulation code that takes into account all kinematical and dynamical effects in the plasma in the presence of bounded waves and external fields.

Bhattacharjee, Sudeep; Sahu, Debaprasad; Pandey, Shail; Chatterjee, Sanghomitro [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India)] [Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Dey, Indranuj [Department of Advanced Energy Engineering Science, Kyushu University, Kasuga Kouen 6-1, Kasuga City 816-8580 (Japan)] [Department of Advanced Energy Engineering Science, Kyushu University, Kasuga Kouen 6-1, Kasuga City 816-8580 (Japan); Roy Chowdhury, Krishanu [Max Planck Institute for the Physics of Complex System, Dresden 01187 (Germany)] [Max Planck Institute for the Physics of Complex System, Dresden 01187 (Germany)

2014-01-15

112

Electron interference in mesoscopic devices in the presence of nonclassical electromagnetic fields  

E-print Network

The interaction of mesoscopic interference devices with nonclassical electromagnetic fields is studied. The external quantum fields induce a phase factor on the electric charges. This phase factor, which is a generalization of the standard Aharonov-Bohm phase factor, is in the case of nonclassical electromagnetic fields a quantum mechanical operator. Its expectation value depends on the density matrix describing the nonclassical photons and determines the interference. Several examples are discussed, which show that the quantum noise of the nonclassical photons destroys slightly the electron interference fringes. An interesting application arises in the context of distant electron interference devices, irradiated with entangled photons. In this case the interfering electrons in the two devices become entangled. The same ideas are applied in the context of SQUID rings irradiated with nonclassical electromagnetic fields. It is shown that the statistics of the Cooper pairs tunneling through the Josephson junction depend on the statistics of the photons.

D. I. Tsomokos; C. C. Chong; A. Vourdas

2005-02-18

113

Verification of electromagnetic fluid-kinetic hybrid electron model in global gyrokinetic particle simulation  

SciTech Connect

The fluid-kinetic hybrid electron model is verified in global gyrokinetic particle simulation of linear electromagnetic drift-Alfvenic instabilities in tokamak. In particular, we have recovered the {beta}-stabilization of the ion temperature gradient mode, transition to collisionless trapped electron mode, and the onset of kinetic ballooning mode as {beta}{sub e} (ratio of electron kinetic pressure to magnetic pressure) increases.

Holod, I.; Lin, Z. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2013-03-15

114

A robust platform cooled by superconducting electronic refrigerators  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

115

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

SciTech Connect

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.

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

2012-05-20

116

Antiproton momentum distributions as a measure of electron cooling force at the Fermilab Recycler  

SciTech Connect

The Fermilab Recycler is a fixed 8 GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel near the ceiling. Electron cooling of high energy antiprotons has recently been demosntrated [1] at the Recycler. Antiproton beam Schottky signals were used to measure the antiproton momentum distribution at equilibrium between a calibrated broadband diffusion source and electron cooling. The large Recycler momentum aperture, the dependence of the electron cooling force as a function of the antiproton momentum deviation and the calibrated diffusion source combine to give a unique sepectral measurement of the antiproton beam momentum distribution.

Broemmelsiek, D.R.; Nagaitsev, S.; /Fermilab

2006-06-01

117

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

SciTech Connect

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)

Andreev, A A; Galkin, A L; Kalashnikov, M P; Korobkin, V V; Romanovsky, Mikhail Yu; Shiryaev, O B [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2011-08-31

118

A System for Cooling Electronic Elements with an EHD Coolant Flow  

NASA Astrophysics Data System (ADS)

A system for cooling electronic components where the liquid coolant flow is forced with ion-drag type EHD micropumps was tested. For tests we used isopropyl alcohol as the coolant and CSD02060 diodes in TO-220 packages as cooled electronic elements. We have studied thermal characteristics of diodes cooled with EHD flow in the function of a coolant flow rate. The transient thermal impedance of the CSD02060 diode cooled with 1.5 ml/min EHD flow was 7.8°C/W. Similar transient thermal impedance can be achieved by applying to the diode a large RAD-A6405A/150 heat sink. We found out that EHD pumps can be successfully applied for cooling electronic elements.

Tanski, M.; Kocik, M.; Barbucha, R.; Garasz, K.; Mizeraczyk, J.; Kra?niewski, J.; Oleksy, M.; Hapka, A.; Janke, W.

2014-04-01

119

Cyclotron-undulator cooling of a free-electron-laser beam  

NASA Astrophysics Data System (ADS)

We propose methods of fast cooling of an electron beam, which are based on wiggling of particles in an undulator in the presence of an axial magnetic field. We use a strong dependence of the axial electron velocity on the oscillatory velocity, when the electron cyclotron frequency is close to the frequency of electron wiggling in the undulator field. The abnormal character of this dependence (when the oscillatory velocity increases with the increase of the input axial velocity) can be a basis of various methods for fast cooling of moderately relativistic (several MeV) electron beams.

Bandurkin, I. V.; Kuzikov, S. V.; Savilov, A. V.

2014-08-01

120

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

SciTech Connect

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 ??=?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.

Tur, A.; Fruit, G.; Louarn, P. [Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS UMR5277/Université Paul Sabatier, Toulouse (France)] [Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS UMR5277/Université Paul Sabatier, Toulouse (France); Yanovsky, V. [Institute for Single Crystals, National Academy of Sciences of Ukraine, Kharkov 61001 (Ukraine)] [Institute for Single Crystals, National Academy of Sciences of Ukraine, Kharkov 61001 (Ukraine)

2014-03-15

121

Kinetic theory of the electron bounce instability in two dimensional current sheets-Full electromagnetic treatment  

NASA Astrophysics Data System (ADS)

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 ? = Bz/Blobes, 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.

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

2014-03-01

122

COMMISSIONING OF THE ELECTRON COOLING DEVICE IN THE HEAVY ION SYNCHROTRON SIS  

Microsoft Academic Search

An electron cooling device has been installed and commis- sioned in the heavy ion synchrotron SIS. The ion beam is cooled and accumulated at the injection energy. The in- tensity of the synchrotron pulses can be increased by up to one order of magnitude in accumulation periods of less than 10 s. The beam emittances at injection energy result from

M. Steck; K. Blasche; H. Eickhoff; B. Franczak; B. Franzke; L. Groening; T. Winkler; V. A. Dolgashev; V. V. Parkhomchuk

123

Experimental investigation of a micro jets - based cooling package for electronic applications  

Microsoft Academic Search

At present, most of the electronic components are cooled by means of heat sinks attached to them and by blowing air with fans. Unfortunately, this technique does not allow removing very high power without the heat sinks size becoming bulky or the fan becoming too large. An even bigger limitation of direct air-cooling appears when dealing with high heat fluxes,

124

Effect of the electromagnetic environment on the single electron transistor  

Microsoft Academic Search

The influence of envirommental impedances on tunneling rates in a single electron transistor circuit is investigated. Effects of the finite gate capacitance and of stray capacitances at the tunnel junctions are considered. For the case of a low impedance environment the electron tunneling rates reduce to the so-called global rule rate while for a high impedance environment a modification of

Gert-Ludwig Ingold; Petra Wyrowski; Hermann Grabert

1991-01-01

125

The nonextensive parameter for nonequilibrium electron gas in an electromagnetic field  

NASA Astrophysics Data System (ADS)

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.

Yu, Haining; Du, Jiulin

2014-11-01

126

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

NASA Astrophysics Data System (ADS)

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.

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.

2014-12-01

127

Optimization of energy conversion during locking of electron bunches by electromagnetic wave in longitudinal electrostatic field  

Microsoft Academic Search

The variational method is used for theoretically optimizing the energy conversion during locking of long electron bunches by the longitudinal field component of a traveling electromagnetic wave with large amplitude E in a longitudinal electrostatic field of intensity E sub st. The governing three nonlinear equations and one inequality for such a distributed system are formulated so as to allow

Y. D. Belyavskiy

1984-01-01

128

Comment on ``Nonrelativistic electromagnetic surface waves: Dispersion properties in a magnetized dusty electron-positron plasma''  

NASA Astrophysics Data System (ADS)

The theory of electromagnetic surface modes propagating along the planar interface between dusty electron-positron plasma and vacuum is reexamined by the conventional matching method of boundary conditions. It is shown that in a magnetoplasma the direct use of specular reflection method is not appropriate and the derivations for the TM-mode dispersion relation [Phys. Rev. E 61, 4357 (2000)] are incorrect.

Misra, Amar P.; Chowdhury, A. Roy

2004-11-01

129

Shielding of a scanning electron microscope against external electro-magnetic fields  

Microsoft Academic Search

We use a box made of 8 mm thick 99.5% aluminium plates for the shielding of a scanning electron microscope against electromagnetic fields that cause distortion in image geometries. The pill-box construction requires a ceiling crane to fit the microscope column into the lower box and to move the upper box (about 150 kg) vertically (inspection, sample change). A knife

Heinz Hilbrecht; Michael Knappertsbusch; Hans R. Thierstein

1995-01-01

130

Comment on 'Nonrelativistic electromagnetic surface waves: Dispersion properties in a magnetized dusty electron-positron plasma'  

SciTech Connect

The theory of electromagnetic surface modes propagating along the planar interface between dusty electron-positron plasma and vacuum is reexamined by the conventional matching method of boundary conditions. It is shown that in a magnetoplasma the direct use of specular reflection method is not appropriate and the derivations for the TM-mode dispersion relation [Phys. Rev. E 61, 4357 (2000)] are incorrect.

Misra, Amar P.; Chowdhury, A. Roy [High Energy Physics Division, Department of Physics, Jadavpur University, Kolkata 700 032 (India)

2004-11-01

131

The excitation of coherent electromagnetic radiation in plasma waveguides by relativistic electron beams  

Microsoft Academic Search

A theoretical analysis is presented of the interaction between a monoenergetic relativistic electron beam and a bounded plasma and the conditions for the generation of electromagnetic radiation in a single mode by such a system are derived. Two specific geometries are considered: (a) a metallic waveguide of radius R, completely filled with plasma which is penetrated by a beam of

B. I. Aronov; L. S. Bogdankevich; A. A. Rukhadze

1976-01-01

132

2008 IEEE Electrical Performance of Electronic Packaging Suppression of Vertical Coupling using Electromagnetic Band Gap Structures  

E-print Network

2008 IEEE Electrical Performance of Electronic Packaging Suppression of Vertical Coupling using Electromagnetic Band Gap Structures Nithya Sankaran, Suzanne Huh, Madhavan Swaminathan and Rao Tummala Packaging are presented. I. Introduction Multilayer packaging plays a vital role in producing highly miniaturized, low

Swaminathan, Madhavan

133

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

SciTech Connect

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.

Wang, J. [Physics Department, Fudan University, Shanghai 210433 (China); Science and Technology on Plasma Physics Laboratory, Mianyang 621900 (China); 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., E-mail: yqgu@caep.ac.cn [Science and Technology on Plasma Physics Laboratory, Mianyang 621900 (China); Cao, L. H. [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

2014-10-15

134

The integration of liquid cryogen cooling and cryocoolers withsuperconducting electronic systems  

SciTech Connect

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.

Green, Michael A.

2003-07-09

135

Electronic Spectra of the Jet-Cooled Acetaminophen  

NASA Astrophysics Data System (ADS)

Resonant two-photon ionization (R2PI), laser induced fluorescence (LIF) and UV-UV double resonance spectra of the jet-cooled acetaminophen, widely used as a pain reliever and fever reducer, were obtained in the gas phase. Conformational characterizations for acetaminophen will be presented with an aid of spectroscopic techniques and DFT B3LYP calculations.

Lee, Seung Jun; Min, Ahreum; Kim, Yusic; Choi, Myong Yong; Chang, Jinyoung; Lee, Sang Hak; Kim, Seong Keun

2010-06-01

136

Diffuser cooling technology for electronic high-density packaging  

Microsoft Academic Search

The original airflow on the VAX 9000 prototype system was well below the rate required to achieve the established cooling and reliability goals. An investigation of the pressure losses through the system established that the exit grille was a major contributor to the overall pressure loss. It was also noted that a large portion of the energy introduced into the

Douglas A. Bailey

1994-01-01

137

One-electron atoms in Schwarzschild universe: bare and electromagnetically dressed cases  

NASA Astrophysics Data System (ADS)

The quantum mechanics of one-electron atoms in the presence of external electromagnetic fields is considered within Weber's framework. The results by the earlier studies are extended in the sense that for given source and field configurations the changes of the electromagnetic potentials due to the curved background are included. The formulation is specialized to the case with Schwarzschild background. The first corrections to the energy levels for bare atom and Zeeman/Stark effects are calculated, exhibiting possible changes in meaningful orders.

Jafari, Abolfazl

2014-06-01

138

Electrostatic and electromagnetic gyroharmonic emissions due to energetic electrons in magnetospheric plasma  

NASA Technical Reports Server (NTRS)

The paper derives the growth rates and growth lengths of the electrostatic emission for spatially homogeneous and inhomogeneous energetic electrons, and numerically evaluates the growth rate and growth length spectra for several parameter sets representative of magnetospheric plasmas. In addition, the growth rates are derived for the case of electromagnetic emission modeled by the ordinary mode. The numerical results of the electromagnetic and electrostatic cases are compared with observations made by satellites in the earth's magnetosphere. It is concluded that the electrostatic gyroharmonic excitation is possible without the cold composition of plasma which is often postulated in the existing literature.

Curtis, S. A.; Wu, C. S.

1979-01-01

139

Final Report for 'ParSEC-Parallel Simulation of Electron Cooling"  

SciTech Connect

The Department of Energy has plans, during the next two or three years, to design an electron cooling section for the collider ring at RHIC (Relativistic Heavy Ion Collider) [1]. Located at Brookhaven National Laboratory (BNL), RHIC is the premier nuclear physics facility. The new cooling section would be part of a proposed luminosity upgrade [2] for RHIC. This electron cooling section will be different from previous electron cooling facilities in three fundamental ways. First, the electron energy will be 50 MeV, as opposed to 100's of keV (or 4 MeV for the electron cooling system now operating at Fermilab [3]). Second, both the electron beam and the ion beam will be bunched, rather than being essentially continuous. Third, the cooling will take place in a collider rather than in a storage ring. Analytical work, in combination with the use and further development of the semi-analytical codes BETACOOL [4,5] and SimCool [6,7] are being pursued at BNL [8] and at other laboratories around the world. However, there is a growing consensus in the field that high-fidelity 3-D particle simulations are required to fully understand the critical cooling physics issues in this new regime. Simulations of the friction coefficient, using the VORPAL code [9], for single gold ions passing once through the interaction region, have been compared with theoretical calculations [10,11], and the results have been presented in conference proceedings papers [8,12,13,14] and presentations [15,16,17]. Charged particles are advanced using a fourth-order Hermite predictor corrector algorithm [18]. The fields in the beam frame are obtained from direct calculation of Coulomb's law, which is more efficient than multipole-type algorithms for less than {approx} 10{sup 6} particles. Because the interaction time is so short, it is necessary to suppress the diffusive aspect of the ion dynamics through the careful use of positrons in the simulations, and to run 100's of simulations with the same physical parameters but with different ''seeds'' for the particle loading. VORPAL can now be used to simulate other electron cooling facilities around the world, and it is also suitable for other accelerator modeling applications of direct interest to the Department of Energy. For example: (a) the Boersch effect in transport of strongly-magnetized electron beams for electron cooling sections, (b) the intrabeam scattering (IBS) effect in heavy ion accelerators, (c) the formation of crystalline beams and (d) target physics for heavy-ion fusion (HIF).

David L Bruhwiler

2005-09-16

140

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

NASA Technical Reports Server (NTRS)

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.

Levinson, Amir; Eichler, David

1992-01-01

141

Nonrelativistic electromagnetic surface waves: Dispersion properties in a magnetized dusty electron-positron plasma  

NASA Astrophysics Data System (ADS)

Nonrelativistic electromagnetic surface waves propagating on the plane interface between dusty electron-positron plasma and vacuum are investigated by specular reflection procedure. In the presence of an applied magnetic field (B0=B0y⁁) directed perpendicular to both the interface normal and the wave vector, transverse electromagnetic modes are studied in terms of the dispersion relation. The analytic modes are derived and discussed with the aid of some numerical analysis. The cold electromagnetic surface wave dispersion relation considering the effect of dust particle shows that possible modes appear only when the normalized frequency (?¯) and the wave vector (K¯) satisfy the condition ?¯?¯, where ?(=n0-/n0+) is the parameter of charge imbalance in the plasma and ?¯ is the normalized cyclotron frequency.

Cho, Sang-Hoon; Lee, Hee J.; Kim, Yong-Soo

2000-04-01

142

Electromagnetic Instabilities, Filamentation, and Focusing of Relativistic Electron Beams  

Microsoft Academic Search

We report nonlinear studies of the Weibel instability of a relativistic electron beam in a plasma. If nb<

Roswell Lee; Martin Lampe

1973-01-01

143

Electromagnetic Oscillations in Cylindrical Plasmas with Electron Beams Interactions  

NASA Astrophysics Data System (ADS)

The dispersion relation for a radial inhomogeneous cylindrical plasma in a strong magnetic field is studied. In order to determine the fundamental transversal magnetic mode (TM_01), we used a numerical algorithm based in expanded Fourier-Bessel functions. Both the effect of the electron beam-plasma interaction and the resonances for a finite transversal cylinder conductor are studied. We used different density profiles and temperatures for the plasma and the beam.

Devia, A.; Arango, P. J.; Barco, H.

144

Fabrication of a diffusion cooled superconducting hot electron bolometer for THz mixing applications  

Microsoft Academic Search

Recent interest in bolometers for heterodyne mixing applications has prompted development of microbridges which are small enough to allow electron diffusion to dominate over electron-phonon interaction as a cooling mechanism. Prior results at 533 GHz have demonstrated several GHz intermediate frequency (IF) bandwidth. Here we describe our processing method in which the bolometer element is a 10 nm thin film

Bruce Bumble; Henry G. LeDuc

1997-01-01

145

Piezoelectric ceramic bimorph coupled to thin metal plate as cooling fan for electronic devices  

Microsoft Academic Search

Several types of piezoelectric fans for cooling electronic devices were constructed and tested at 60 Hz, 110 V and 220 V, respectively. The aim of the work is to investigate the possibility of replacing the rotary type of fan in some noise-sensitive electronic devices. Different vibrating metal plates were tested and analyzed theoretically. It is found that the resonant frequency

Ju Hyun Yoo; Jae Il Hong; Wenwn Cao

2000-01-01

146

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

SciTech Connect

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.

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

2011-03-01

147

Effect of electron density profile on power absorption of high frequency electromagnetic waves in plasma  

SciTech Connect

Considering different typical electron density profiles, a multi slab approximation model is built up to study the power absorption of broadband (0.75-30 GHz) electromagnetic waves in a partially ionized nonuniform magnetized plasma layer. Based on the model, the power absorption spectra for six cases are numerically calculated and analyzed. It is shown that the absorption strongly depends on the electron density fluctuant profile, the background electron number density, and the collision frequency. A potential optimum profile is also analyzed and studied with some particular parameters.

Xi Yanbin; Liu Yue [MOE Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

2012-07-15

148

An electromagnetic/electrostatic dual cathode system for electron beam instruments  

NASA Technical Reports Server (NTRS)

A method of providing cathode redundancy which consists of two fixed cathodes and uses electromagnetic and/or electrostatic fields to direct the electron beam to the electron optical axis is presented, with application to the cathode system of the Scanning Electron Microscope and Particle Analyzer proposed for NASA's Mariner Mark II Comet Rendezvous/Asteroid Flyby projected for the 1990s. The symmetric double deflection system chosen has the optical property that the image of the effective electron source is formed above the magnet assembly near the apparent position of the effective source, and it makes the transverse positions of the electron sources independent of the electron beam energy. Good performance of the system is found, with the sample imaging resolution being the same as for the single-axis cathode.

Bradley, J. G.; Conley, J. M.; Wittry, D. B.; Albee, A. L.

1986-01-01

149

Transverse Feedback for Electron-Cooled DC-Beam at COSY  

SciTech Connect

At the cooler synchrotron COSY, high beam quality is achieved by means of beam cooling. In the case of intense electron-cooled beams, fast particle losses due to transverse coherent beam oscillations are regularly observed. To damp the instabilities a transverse feedback system was installed and successfully commissioned. Commissioning of the feedback system resulted in a significant increase of the e-cooled beam intensity by single injection and when cooling and stacking of repeated injections is applied. External experiments profit from the small diameter beams and the reduced halo. A transverse damping system utilizing a pick-up, signal processing electronics, power amplifiers, and a stripline deflector is introduced. Beam current and Schottky spectra measurements with the vertical feedback system turned on and off are presented.

Kamerdzhiev, V.; Dietrich, J. [Forschungszentrum Juelich GmbH, Institut fuer Kernphysik (Germany)

2004-11-10

150

Multi-objective thermal design optimization and comparative analysis of electronics cooling technologies  

Microsoft Academic Search

A multi-objective thermal design optimization and comparative study of electronics cooling technologies is presented. The cooling technologies considered are: continuous parallel micro-channel heat sinks, in-line and staggered circular pin-fin heat sinks, offset strip fin heat sinks, and single and multiple submerged impinging jet(s). Using water and HFE-7000 as coolants, Matlab’s multi-objective genetic algorithm functions were utilized to determine the optimal

Sidy Ndao; Yoav Peles; Michael K. Jensen

2009-01-01

151

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

152

Microminiature refrigerators for Joule-Thomson cooling of electronic chips and devices  

NASA Astrophysics Data System (ADS)

The speed, reliability, and noise characteristics of most semiconductor devices improve with cooling to cryogenic temperatures. In addition, certain unique capabilities become available at these temperatures through the use of superconducting electronics. Progress in the development of the technology for the selective or 'spot cooling' of devices and individual chips using microminiature Joule-Thomson refrigerators for the lower temperature range is discussed. Also discussed are the recent developmet of circuit board coolers for higher temperature applications for the cooling of CMOS, PALs, SRAM and DRAM devices, using related, compressed vapor refrigerators with higher refrigeration capacity than the low temperature, J-T refrigerators.

Little, W. A.

153

Hot Electron Cooling Dynamics of Nanolithographcally Prepared Au Arrays  

Microsoft Academic Search

The relaxation dynamics of Au arrays prepared via nanosphere lithography were investigated1 using femtosecond pump-probe spectroscopy. The hot electron relaxation dynamics of arrays of truncated tetrahedra shaped 90 nm gold nanoparticles on glass, 50nm gold thin film, and gold nanodots in solution are compared. The initial relaxation (due to the electron-phonon relaxation) of the Au array is longer (2.9 ps)

David Hathcock; Stephan Link; Mostafa El-Sayed

2003-01-01

154

Liquid flow-through cooling of electronic modules  

Microsoft Academic Search

Thermal management of future avionics modules will be a critical design issue. New advances in integrated circuit technology and electronic packaging will allow the design of densely populated electronics modules with potential power dissipation levels in excess of 1.0 W\\/cm(exp 2). While the module power level trend will be to increase, the maximum allowable junction temperature for integrated circuits may

S. Sridhar; M. D. Osterman; J. M. Carbonell; K. E. Herold

1994-01-01

155

Electromagnetic wave analogue of an electronic diode This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Electromagnetic wave analogue of an electronic diode This article has been downloaded from n ­ a c c e s s j o u r n a l f o r p h y s i c s New Journal of Physics Electromagnetic wave functionality for electromagnetic waves, an electromagnetic isolator, is based on the Faraday effect of rotation

Zheludev, Nikolay

156

Pitch-Angle Scattering of Relativistic Electrons by Electromagnetic Ion Cyclotron Waves in the Magnetosphere  

NASA Astrophysics Data System (ADS)

Electromagnetic ion cyclotron (EMIC) waves which propagate at frequencies near the proton gyrofrequency can interact with relativistic electrons in the outer radiation belt, through cyclotron resonance, and cause pitch-angle scattering. During magnetic storms EMIC wave amplitudes can exceed the level required for strong diffusion scattering and significant electron losses to the atmosphere can occur over many drift orbits. The Combined Release and Radiation Effects Satellite (CRRES) was ideally situated to observe EMIC waves in the middle magnetosphere. In this study observations from CRRES are used to obtain spectral properties of EMIC waves (1-10 nT), and thus determine typical pitch-angle diffusion coefficients, D? ? , during different phases of a storm. These diffusion rates are then compared to theoretical calculations assuming a simple functional form for D? ? based on quasi-linear theory that is valid for parallel propagating electromagnetic waves.

Loto'Aniu, T. M.; Thorne, R. M.; Fraser, B. J.; Horne, R.

2003-12-01

157

Microwave Reflection Measurements of Electron Densities in Electromagnetically Driven Shock-Produced Plasmas  

Microsoft Academic Search

The electron densities from 1013 to 1017 cm?3 in plasmas produced by electromagnetically driven, propagating, or reflected shock waves are measured by a microwave reflection method. The Mach number of the shock waves is varied from 9 to 25 in argon, air, and helium at initial pressures from 0.4 to 2.0 Torr. A 35-GHz microwave reflection probe is inserted into

Akimasa Funahashi; Susumu Takeda

1968-01-01

158

Charge Symmetry Breaking in Electromagnetic Nucleon Form Factors in Elastic Parity-Violating Electron-Nucleus Scattering  

E-print Network

The effects of charge symmetry breaking in nucleon electromagnetic form factors on parity- violating elastic electron-12C scattering is studied, and found to be much smaller than other known effects. The analysis of a planned experiment is discussed.

Miller, Gerald A

2014-01-01

159

Electromagnetic surface modes in a magnetized quantum electron-hole plasma.  

PubMed

The propagation of surface electromagnetic waves along a uniform magnetic field is studied in a quantum electron-hole semiconductor plasma. A forward propagating mode is found by including the effect of quantum tunneling. In the classical limit (??0), one of the low-frequency modes found is similar to an experimentally observed one in n-type InSb at room temperature. The surface modes are shown to be significantly modified in the case of high-conductivity semiconductor plasmas where electrons and holes may be degenerate. The effects of the external magnetic field and the quantum tunneling on the surface wave modes are discussed. PMID:21728700

Misra, A P

2011-05-01

160

Small Loop Heat Pipe with Plastic Wick for Electronics Cooling  

NASA Astrophysics Data System (ADS)

In this paper, fabrication and test results of a small loop heat pipe (LHP) for electric cooling over a distance of 1100 mm are discussed. Poly(tetrafluoroethylene) porous material with 1.2 µm pore radius was used as a wick material for a primary pump of the loop to satisfy in both high thermal performance and low cost. High-grade ethanol was selected as a working fluid inside the loop. The small LHP with an outer diameter of 12 mm and length of 77 mm of an evaporator was made of stainless steel. The vapor and liquid transport lines are 1.8 mm in inner diameter and 1100 mm in length respectively in order to demonstrate the long-distance heat transport in a small tube, against the frictional resistance in the loop. The start-up process was monitored with an infrared camera, and quick start-up and its stable operation after the start-up were visually demonstrated. The loop could operate up to 50 W heat load with the operating temperature of around 70 °C in the evaporator. The thermal resistance between the evaporator and the condenser of the loop was 0.58 K/W at 50 W.

Nagano, Hosei; Nishigawara, Masahito

2011-11-01

161

Thermomagnetic Convection in Square and Shallow Enclosures for Electronics Cooling  

Microsoft Academic Search

Combined temperature and magnetic field gradients established in ferrofluids induce thermomagnetic convection. We report a comparative numerical analysis of steady-state convection carried out for a square and a shallow enclosure under zero-gravity conditions. Two symmetrically placed, discrete, constant-flux flush-mounted heaters on the bottom wall of the cavities represent power-dissipating devices in electronics\\/MEMS applications. The sidewalls serve as heat sinks. A

Sumanta Banerjee; Achintya Mukhopadhyay; Swarnendu Sen; Ranjan Ganguly

2009-01-01

162

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

NASA Astrophysics Data System (ADS)

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 Campaign SSRC at HAARP. The analytical results for the SIB waves at the 3rd and 4th gyroharmonics will be presented which shows good agreement with experimental data. The variation of Stimulated Electromagnetic Emission (SEE) spectrum during generation of the artificial plasma layer by HAARP transmitter has been studied during 2012 PARS campaign. It turns out that SEE features observed during the formation of artificial plasma layers may be used as a diagnostic tool to investigate the generation source of these artificial layers. Both experimental data and analytical results will be presented.

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

2012-12-01

163

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

SciTech Connect

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.

Not Available

2011-07-01

164

Performance of two-step thermoelectric-adsorption heat pump for harsh environment electronics cooling  

Microsoft Academic Search

Performance of a two-stage thermoelectric adsorption heat pump for electronics cooling in a thermally harsh environment has been presented. Adsorption heat pumps have few moving parts, which make them suitable for use in harsh environments that are prone to mechanical shock and high temperatures. Use of a thermoelectric device for heat regeneration during the adsorption-desorption process promises to make the

Ashish Sinha; Yogendra Joshi

2010-01-01

165

Turbulence modelling and it's impact on CFD predictions for cooling of electronic components  

Microsoft Academic Search

This paper will discuss Computational Fluid Dynamics (CFD) results from an investigation into the accuracy of several turbulence models to predict air cooling for electronic packages and systems. Also new transitional turbulence models will be proposed with emphasis on hybrid techniques that use the k-? model at an appropriate distance away from the wall and suitable models, with wall functions,

K. K. Dhinsa; C. J. Bailey; K. A. Pericleous

2004-01-01

166

Metamorphic materials: bulk electromagnetic transitions realized in electronically reconfigurable composite media.  

PubMed

We present what we believe is a new class of composite electromagnetic materials characterized by the concept of metamorphism, which we define in general terms. Metamorphic materials exhibit bulk electromagnetic transitions among states characterized by distinct ranges of values of their reflection coefficient. Each such state has unique physical properties induced by the corresponding values of the reflection coefficient. We present a variety of physical realizations of the concept of metamorphic materials in microwave frequencies, showing with specific metallodielectric designs how transitions among metamorphic states can be obtained at the same frequency, for fixed material geometries, by electronic reconfigurability. We further show how a given material exhibiting certain metamorphic states at a given frequency can transform into a different combination of metamorphic states at different frequencies; i.e., metamorphic materials have a useful dispersive degree of freedom. PMID:17047724

Kyriazidou, Chryssoula A; Contopanagos, Harry F; Alexopoulos, Nicolaos G

2006-11-01

167

Effect of Higher Order Axial Electron Temperature on Self-Focusing of Electromagnetic Pulsed Beam in Collisional Plasma  

NASA Astrophysics Data System (ADS)

Effect of higher order axial electron temperature on self-focusing of electromagnetic pulsed beam in collisional plasma is investigated. It is shown that higher order axial electron temperature Tp4 is not trivial than Tp0 and Tp2, which can modify slightly radial redistribution of electron density and increases effective dielectric constant. As a result, on one hand, slightly reduce electromagnetic beam self-focusing in the course of oscillatory convergence, on the other hand, quicken beam divergence in the course of steady divergence, i.e., higher order axial electron temperature Tp4 can decrease the influence of collisional nonlinearity in collisional plasma.

Xia, Xiong-Ping; Yi, Lin

2012-05-01

168

Nonlinear interaction of intense electromagnetic waves with a magnetoactive electron-positron-ion plasma  

NASA Astrophysics Data System (ADS)

The nonlinear coupling between circularly polarized electromagnetic (CPEM) waves and acoustic-like waves in a magnetoactive electron-positron-ion (e-p-i) plasma is studied, taking into account the relativistic motion of electrons and positrons. The possibility of modulational instability and its growth rate as well as the envelope soliton formation and its characteristics in such plasmas are investigated. It is found that the growth rate of modulation instability increases in the case that ?c/? <1 (?c and ? are the electron gyrofrequency and the CPEM wave frequency, respectively) and decreases in the case that ?c/? >1. It is also shown that in a magnetoactive e-p-i plasma, the width of bright soliton increases/decreases in case of (?c/?)<1/(?c/?)>1 by increasing the magnetic field strength.

Khorashadizadeh, S. M.; Rastbood, E.; Zeinaddini Meymand, H.; Niknam, A. R.

2013-08-01

169

Nonlinear interaction of intense electromagnetic waves with a magnetoactive electron-positron-ion plasma  

SciTech Connect

The nonlinear coupling between circularly polarized electromagnetic (CPEM) waves and acoustic-like waves in a magnetoactive electron-positron-ion (e-p-i) plasma is studied, taking into account the relativistic motion of electrons and positrons. The possibility of modulational instability and its growth rate as well as the envelope soliton formation and its characteristics in such plasmas are investigated. It is found that the growth rate of modulation instability increases in the case that ?{sub c}/?<1 (?{sub c} and ? are the electron gyrofrequency and the CPEM wave frequency, respectively) and decreases in the case that ?{sub c}/?>1. It is also shown that in a magnetoactive e-p-i plasma, the width of bright soliton increases/decreases in case of (?{sub c}/?)<1/(?{sub c}/?)>1 by increasing the magnetic field strength.

Khorashadizadeh, S. M.; Rastbood, E.; Zeinaddini Meymand, H. [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of)] [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of); Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)

2013-08-15

170

Surface-plasmon-assisted electron pair formation in strong electromagnetic field  

NASA Astrophysics Data System (ADS)

In this work the strong electromagnetic field of femtosecond Ti:Sa lasers was used to excite surface plasmon oscillations (SPOs) in gold films at room temperature in the Kretschmann geometry. Experimental investigations were carried out using a surface plasmon near field scanning tunneling microscope, measuring its response to excitation at SPO hot spots on the gold surface. Furthermore, the spectra of photoelectrons, liberated by multiplasmon absorption, have also been measured by a time-of-flight spectrometer. In both cases new type of anomalies in both the STM and electron TOF signals have been measured in the same laser intensity range. The existence of these anomalies may be qualitatively understood, by using the intensity-dependent expression for the effective electron-electron scattering potential, derived earlier in a different context. In this theoretical work an effective attraction potential has been predicted in the presence of strong inhomogeneous radiation fields.

Kroó, N.; Rácz, P.; Varró, S.

2014-03-01

171

Cryogenic systems for proof of the principle experiment of coherent electron cooling at RHIC  

NASA Astrophysics Data System (ADS)

The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the beam luminosity in certain cases, by as much as tenfold. Within the scope of this project, a 112 MHz, 2MeV Superconducting Radio Frequency (SRF) electron gun and a 704 MHz 20MeV 5-cell SRF cavity will be installed at IP2 in the RHIC ring. The superconducting RF electron gun will be cooled in a liquid helium bath at 4.4 K. The 704 MHz 5-cell SRF cavity will be cooled in a super-fluid helium bath at 2.0 K. This paper discusses the cryogenic systems designed for both cavities. For the 112 MHz cavity cryogenic system, a condenser/boiler heat exchanger is used to isolate the cavity helium bath from pressure pulses and microphonics noise sources. For the 704 MHz 5-cell SRF cavity, a heat exchanger is also used to isolate the SRF cavity helium bath from noise sources in the sub-atmospheric pumping system operating at room temperature. Detailed designs, thermal analyses and discussions for both systems will be presented in this paper.

Huang, Yuenian; Belomestnykh, Sergey; Brutus, Jean Clifford; Lederle, Dewey; Orfin, Paul; Skaritka, John; Soria, Victor; Tallerico, Thomas; Than, Roberto

2014-01-01

172

Cryogenic systems for proof of the principle experiment of coherent electron cooling at RHIC  

SciTech Connect

The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the beam luminosity in certain cases, by as much as tenfold. Within the scope of this project, a 112 MHz, 2MeV Superconducting Radio Frequency (SRF) electron gun and a 704 MHz 20MeV 5-cell SRF cavity will be installed at IP2 in the RHIC ring. The superconducting RF electron gun will be cooled in a liquid helium bath at 4.4 K. The 704 MHz 5-cell SRF cavity will be cooled in a super-fluid helium bath at 2.0 K. This paper discusses the cryogenic systems designed for both cavities. For the 112 MHz cavity cryogenic system, a condenser/boiler heat exchanger is used to isolate the cavity helium bath from pressure pulses and microphonics noise sources. For the 704 MHz 5-cell SRF cavity, a heat exchanger is also used to isolate the SRF cavity helium bath from noise sources in the sub-atmospheric pumping system operating at room temperature. Detailed designs, thermal analyses and discussions for both systems will be presented in this paper.

Huang, Yuenian; Belomestnykh, Sergey; Brutus, Jean Clifford; Lederle, Dewey; Orfin, Paul; Skaritka, John; Soria, Victor; Tallerico, Thomas; Than, Roberto [Collider Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2014-01-29

173

Reflection of electromagnetic radiation from plasma with an anisotropic electron velocity distribution  

SciTech Connect

The reflection of a test electromagnetic pulse from the plasma formed as a result of tunnel ionization of atoms in the field of a circularly polarized high-power radiation pulse is analyzed using the kinetic approach to describe electron motion. It is shown that the reflected pulse is significantly amplified due to the development of Weibel instability. The amplification efficiency is determined by the maximum value of the instability growth rate, which depends on the degree of anisotropy of the photoelectron distribution function.

Vagin, K. Yu., E-mail: vagin@sci.lebedev.ru; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2013-08-15

174

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

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

175

THEORY OF UNIFORM-MOTION ELECTROMAGNETIC MACHINES Electron Tube Division, THOMSON-C. S. F., Paris, France  

E-print Network

252 THEORY OF UNIFORM-MOTION ELECTROMAGNETIC MACHINES G. MOURIER Electron Tube Division, THOMSON (moteurs, alternateurs, etc...) et les tubes électroniques de structure périodique, et on établit une...) and periodic-structure microwave electron tubes are made, and a common theory is elaborated. In the second part

Paris-Sud XI, Université de

176

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

SciTech Connect

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.

Rahmani, Z., E-mail: z.rahmani@kashanu.ac.ir; Jazi, B. [Department of Laser and Photonics, Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Heidari-Semiromi, E. [Department of Condense Matter, Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of)

2014-09-15

177

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

SciTech Connect

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.

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

178

Radiation of long electromagnetic waves by a modulated electron beam in the ionosphere  

NASA Astrophysics Data System (ADS)

Pulsed electron beams in the ionosphere radiate electromagnetic energy and, therefore, might work as wireless virtual antennas. Such virtual antennas would be most useful at low frequencies because small or moderate-size wire antennas work well at high frequencies. Natural beams radiate energy that propagates down through the ionosphere, but no experiment has used a man-made electron beam to produce radiation at the modulation frequency or its harmonics, and detected that radiation on the ground. The present report addresses the feasibility of such an experiment, and suggests preferred configurations. Motivated by communications applications, which require good time availability, it considers only phenomena, such as the triggering plasma of instabilities or guidance in transient ionospheric ducts.

Field, E. C.; Johnson, L. E.

1985-12-01

179

Electromagnetic surface modes in a magnetized quantum electron-hole plasma  

SciTech Connect

The propagation of surface electromagnetic waves along a uniform magnetic field is studied in a quantum electron-hole semiconductor plasma. A forward propagating mode is found by including the effect of quantum tunneling. In the classical limit (({h_bar}/2{pi}){yields}0), one of the low-frequency modes found is similar to an experimentally observed one in n-type InSb at room temperature. The surface modes are shown to be significantly modified in the case of high-conductivity semiconductor plasmas where electrons and holes may be degenerate. The effects of the external magnetic field and the quantum tunneling on the surface wave modes are discussed.

Misra, A. P. [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden)

2011-05-15

180

Low Noise in a Diffusion-Cooled Hot-Electron Mixer at 2.5 THz  

NASA Technical Reports Server (NTRS)

The noise performance of a Nb hot-electron bolometer mixer at 2.5 THz has been investigated. The devices are fabricated from a 12-nm-thick Nb film, and have a 0.30 micrometer x 0.15 micrometer in-plane size, thus exploiting diffusion as the electron cooling mechanism. The rf coupling was provided by a twin-slot planar antenna on an elliptical Si lens. The experimentally measured double sideband noise temperature of the receiver was as low as 2750 +/- 250 K with an estimated mixer noise temperature of approximately equal 900 K. The mixer bandwidth derived from both noise bandwidth and IF impedance measurements was approximately equal 1.4 GHz. These results demonstrate the low-noise operation of the diffusion-cooled bolometer mixer above 2 THz.

Karasik, B. S.; Gaidis, M. C.; McGrath, W. R.; Bumble, B.; LeDuc, H. G.

1997-01-01

181

Simultaneous observations of subauroral electron temperature enhancements and electromagnetic ion cyclotron waves  

NASA Technical Reports Server (NTRS)

Observational results from an investigation of LF (0.5-4.0 Hz) electromagnetic ion cyclotron waves and subauroral electron temperature enhancements recorded from the DE-2 satellite are presented. Four different wave events were analyzed, all recorded at magnetic latitudes from 57-60 deg, magnetic local times from 8-14 hr, and altitudes from 600-900 km. The peak wave amplitudes during the events ranged from 8-70 nT and 5-30 mV/m in the magnetic and electric field, respectively. Te enhancements at the time of the waves were observed in three of four events. A linear relationship between the wave magnetic field spectral density and Te enhancements was found for these events. The Te enhancements were also correlated with an enhanced flux of low energy electrons. During one event (82104) an enhanced flux of electrons were observed at energies up to 50 eV and at nearly all pitch angles, although the flux was largest in the precipitating and upflowing directions. It is suggested that the waves are responsible for heating the low energy electrons which precipitate to the ionosphere and produce the observed Te enhancements. The upflowing electron population appears to be heated at ionospheric altitudes, below the DE-2 satellite.

Erlandson, R. E.; Aggson, T. L.; Hogey, W. R.; Slavin, J. A.

1993-01-01

182

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

Microsoft Academic Search

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

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

2009-01-01

183

Analysis of two-layered micro-channel heat sink concept in electronic cooling  

Microsoft Academic Search

In this work, a new concept for a two-layered micro-channel heat sink with counter current flow arrangement for cooling of the electronic components is proposed. The thermal performance and the temperature distribution for these types of micro channels were analyzed and a procedure for optimizing the geometrical design parameters is presented. While the power supply system of the two-layered design

Kambiz Vafai; Lu Zhu

1999-01-01

184

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

SciTech Connect

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.

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

2012-07-01

185

Transient thermal and hydrodynamic model of flat heat pipe for the cooling of electronics components  

Microsoft Academic Search

The transient performance of a flat heat pipe (FHP) used to cool multiple electronics components, is presented in this paper. The fluid flows in both wick and vapor core were computed using a transient 2D hydrodynamic model (T2DHM). This model was coupled with a transient 3D thermal model (T3DTM) of the FHP wall, designed to calculate the heat transfer through

R. Sonan; S. Harmand; J. Pellé; D. Leger; M. Fakès

2008-01-01

186

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

187

A perturbation theory study of electron vortices in electromagnetic fields: the case of infinitely long line charge and magnetic dipole.  

PubMed

The novel discovery of electron vortices carrying quantized orbital angular momentum motivated intensive research of their basic properties as well as applications, e.g. structural characterization of magnetic materials. In this paper, the fundamental interactions of electron vortices within infinitely long atomic-column-like electromagnetic fields are studied based on the relativistically corrected Pauli-Schrödinger equation and the perturbation theory. The relative strengths of three fundamental interactions, i.e. the electron-electric potential interaction, the electron-magnetic potential/field interaction and the spin-orbit coupling are discussed. The results suggest that the perturbation energies of the last two interactions are in an order of 10(3)-10(4) smaller than that of the first one for electron vortices. In addition, it is also found that the strengths of these interactions are strongly dependant on the spatial distributions of the electromagnetic field as well as the electron vortices. PMID:24690540

Xie, L; Wang, P; Pan, X Q

2014-08-01

188

Low Energy Electron Cooling and Accelerator Physics for the Heidelberg CSR  

SciTech Connect

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.

Fadil, H.; Grieser, M.; Hahn, R. von; Orlov, D.; Schwalm, D.; Wolf, A. [Max-Planck-Institute fuer Kernphysik, Saupfercheckweg 1 D-69117 Heidelberg (Germany); Zajfman, D. [Max-Planck-Institute fuer Kernphysik, Saupfercheckweg 1 D-69117 Heidelberg (Germany); Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100 (Israel)

2006-03-20

189

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

NASA Technical Reports Server (NTRS)

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.

Koch, L. Danielle; VanZante, Dale E.

2006-01-01

190

The Effects of Frame and Inlet Sizes of Electronic Casing-Mounted Cooling Fans on Their PQ Characteristics  

Microsoft Academic Search

This paper describes the effects of frame and inlet sizes of an electronic casing on the cooling fan performance. The performance of air-cooling fans is defined by their P-Q characteristics. Recent studies report that P-Q curves of cooling fans depend considerably on their operational environments. It is impossible for accurate CFD (Computational Fluid Dynamics) analyses to be performed on the

Takashi Fukue; Takafumi Yoshimoto; Masaru Ishizuka; Shinji Nakagawa

2009-01-01

191

Stability of a transverse electromagnetic wave in electrons streaming parallel to an external electric field  

SciTech Connect

The stability of a circularly polarized electromagnetic wave convected by a dense electron beam in an external longitudinal electrostatic field is studied. It is shown that when the electron density in the stream is high enough the amplitude a of the wave is an S-shaped function of the potential U of the longitudinal field (in the quasistatic approximation). An approximate solution is found for the self-consistent problem. This is compared with the results of numerical simulation and the linear perturbation theory, which makes it possible to demonstrate and describe the instability of the quasistatic stream-wave system when the function a(U) is decreasing. The instability occurs regardless of the direction of the longitudinal field, associated with the negative sign of the wave energy, and can be interpreted as {open_quotes}slipping{close_quotes} of the fields inside the beam relative to the electron flow. The nature of the quasiequilibrium electron states when the function a(U) is decreasing is also discussed. 5 refs., 2 figs.

Minaev, Yu.A.; Pogorelov, E.N.

1992-09-01

192

Near-Infrared Spectroscopy at McDonald Observatory: B.1 The CoolSpec Electronics Control System  

E-print Network

Spec Electronics Control System CoolSpec is near-infrared, grating spectrometer available for use on the 2.7-m the spectrometer optics; the dewar is coupled to an independent near-infrared camera, ROKCAM (see Appendix A), which acts as the detector for the spectrometer. CoolSpec can perform J, H, and K-band spectroscopy

Colorado at Boulder, University of

193

Effect of Beam Current Fluctuations in the Electron Cooler on the Cooled Ion Beam in RHIC II.  

E-print Network

. Assuming that electron bunches have a uniform longitudinal distribution of length l and an axially of the cooling section that, as discussed above, justifies the impulse approximation of the interaction of RHIC

194

The interaction of electromagnetic wave and plasma wave in an electron beam-ion channel system  

SciTech Connect

The features of the waves and the instability induced by the interaction of electromagnetic (EM) wave with plasma wave in the electron beam-ion channel system are studied. Characteristics of waves in the system are displayed through the dispersion relation and two kinds of EM instabilities are found. The first one is excited by the interaction of the fast plasma wave and the forward EM wave, and the other one is induced by the coupling of the fast plasma wave and the backward EM wave, the numerical results show that this is caused by the virtual cathode oscillation. The conditions of these EM instabilities are given and the related physical mechanisms have been discussed in detail.

Su, D.; Tang, C. J. [Key Laboratory of High Energy Density Physics and Technology, Ministry of Education, Sichuan University, Chengdu, 610064 (China)

2011-02-15

195

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

SciTech Connect

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.

Zhukov, Alexander V., E-mail: alex-zhukov@sutd.edu.sg; Bouffanais, Roland [Singapore University of Technology and Design, 20 Dover Drive, Singapore 138682 (Singapore); Fedorov, E. G. [Volgograd State University of Architecture and Civil Engineering, 400074 Volgograd (Russian Federation); Belonenko, Mikhail B. [Laboratory of Nanotechnology, Volgograd Institute of Business, 400048 Volgograd (Russian Federation)

2014-05-28

196

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

SciTech Connect

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 easily scaleable for this larger load.

Lowe, K.T.

2005-10-07

197

Effects of finite electron mean free path on the attenuation, electromagnetic generation, and detection of ultrasonic shear waves in superconductors  

Microsoft Academic Search

Use of the general many-body formalism allows us to derive a system of equations describing the propagation of electromagnetic shear waves coupled to ultrasonic shear waves in normal and superconducting metals with arbitrary electron mean free paths. From this system of equations we derive general expressions in terms of correlation functions for the attenuation coefficient as well as for the

Kurt Scharnberg

1978-01-01

198

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

ERIC Educational Resources Information Center

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…

Murphy, Maureen Kendrick

2010-01-01

199

Nonlinear perpendicular propagation of ordinary mode electromagnetic wave packets in pair plasmas and electron-positron-ion plasmas  

Microsoft Academic Search

The nonlinear amplitude modulation of electromagnetic waves propagating in pair plasmas, e.g., electron-positron or fullerene pair-ion plasmas, as well as three-component pair plasmas, e.g., electron-positron-ion plasmas or doped (dusty) fullerene pair-ion plasmas, assuming wave propagation in a direction perpendicular to the ambient magnetic field, obeying the ordinary (O-) mode dispersion characteristics. Adopting a multiple scales (reductive perturbation) technique, a nonlinear

I. Kourakis; F. Verheest; N. F. Cramer

2007-01-01

200

Electromagnetic Abdulaziz Hanif  

E-print Network

Electromagnetic Propulsion Abdulaziz Hanif Electrical Engineering Department King Fahd University of spacecraft, which would be jolted through space by electromagnets, could take us farther than any of these other methods. When cooled to extremely low temperatures, electromagnets demonstrate an unusual behavior

Masoudi, Husain M.

201

Possible modification of the cooling index of interstellar helium pickup ions by electron impact ionization in the inner heliosphere  

NASA Astrophysics Data System (ADS)

neutrals penetrating into the inner heliosphere are ionized by photoionization, charge exchange with solar wind ions, and electron impact ionization. These processes comprise the first step in the evolution of interstellar pickup ion (PUI) distributions. Typically, PUI distributions have been described in terms of velocity distribution functions that cool adiabatically under solar wind expansion, with a cooling index of 3/2. Recently, the cooling index has been determined experimentally in observations of He PUI distributions with Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer and found to vary substantially over the solar cycle. The experimental determination of the cooling index depends on the knowledge of the ionization rates and their spatial variation. Usually, ionization rates increase with 1/r2 as neutral particles approach the Sun, which is not exactly true for electron impact ionization, because the electron temperature increases with decreasing distance from the Sun due to the complexity of its distributions and different radial gradients in temperature. This different dependence on distance may become important in the study of the evolution of PUI distributions and is suspected as one of the potential reasons for the observed variation of the cooling index. Therefore, we investigate in this paper the impact of electron ionization on the variability of the cooling index. We find that the deviation of the electron ionization rate from the canonical 1/r2 behavior of other ionization processes plays only a minor role.

Chen, Jun Hong; Bochsler, Peter; Möbius, Eberhard; Gloeckler, George

2014-09-01

202

Methods of beam cooling  

SciTech Connect

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.

Sessler, A.M.

1996-02-01

203

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

SciTech Connect

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.

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

2012-05-20

204

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

SciTech Connect

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.

Rufai, O. R., E-mail: rajirufai@gmail.com; Bharuthram, R., E-mail: rbharuthram@uwc.ac.za [University of the Western Cape, Belville (South Africa); Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: lakhina@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai (India)

2014-08-15

205

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

206

Cool Timepix - Electronic noise of the Timepix readout chip down to -125 °C  

NASA Astrophysics Data System (ADS)

The Timepix readout chip with its 65k pixels on a sensitive area of 14 mm×14 mm provides a fine spatial resolution for particle tracking or medical imaging. We explore the operation of Timepix in a dual-phase xenon environment (around -110 °C). Used in dual-phase xenon time projection chambers, e.g. for dark matter search experiments, the readout must have a sufficiently low detection limit for small energy deposits. We measured the electronic pixel noise of three bare Timepix chips. For the first time Timepix readout chips were cooled to temperatures as low as -125 °C. In this work, we present the results of analysing noise transition curves recorded while applying a well-defined charge to the pixel's input. The electronic noise reduces to an average of 99e-, a reduction of 23% compared to operation at room temperature.

Schön, R.; Alfonsi, M.; van Bakel, N.; van Beuzekom, M.; Koffeman, E.

2015-01-01

207

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

SciTech Connect

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.

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

2009-05-01

208

Investigation of negative ion generation in a cusp plasma electromagnetic trap with a hollow-cathode Penning source of electrons  

NASA Astrophysics Data System (ADS)

Results are reported from experimental studies of negative ion generation in a cusp plasma electromagnetic trap by using an electron beam injected into the trap. Owing to a wide energy distribution of the electron beam, a one-chamber scheme of negative ion generation could be realized in the trap. A negative hydrogen ion current of 300 ?A with a density of 0.7 mA/cm2 was obtained for an injected electron beam current of 300 mA at conditions far from optimum.

Petrushenya, A. A.; Borisko, V. N.

2004-05-01

209

Electronic properties of carbon nanotubes investigated by means of standard electromagnetic simulators  

NASA Astrophysics Data System (ADS)

Due to the formal analogy between Maxwell and Schrödinger equations, electromagnetic (e.m.) simulators may become a powerful numerical tool for the analysis of carrier transport in low-dimensional systems. In the following, we exploit this analogy in order to investigate the electronic properties of carbon nanotubes (CNTs). As a matter of fact, e.m. commercial solvers have reached a high degree of efficiency due to the demand of the high-speed and microwave circuit market. In this paper, we suggest applying e.m. numerical solvers to CNTs with a view to derive their main properties, such as dispersion curves and effective masses. In particular, we have used the “CST Microwave Studio,” implementing a finite element method (FEM). However, many other e.m. solvers are available, exploiting different approaches (FDTD, Method of Moment, TLM, etc.). In order to assess the validity of the approach, we have investigated an important example of band-gap distortion and splitting of degenerate states with respect to the angular momentum, due to an external electric field. The model can also be applied in order to better explain the behavior of metal-CNT contacts, representing a critical point for analysis and synthesis of nanotransistor devices.

Mencarelli, Davide; Rozzi, Tullio; Maccari, Luca; di Donato, Andrea; Farina, Marco

2007-02-01

210

JOURNAL DE PHYSIQUE Colloque C7, supplement au n7 , Tome 40, Juillet 1979, page C7-823 MEASUREMENT OF ELECTRON DENSITY BY ELECTROMAGNETIC WAVES  

E-print Network

MEASUREMENT OF ELECTRON DENSITY BY ELECTROMAGNETIC WAVES WHICH PROPAGATE ON A MAGNETIZED PLASMA COLUMN D surface wave propagation data has . . . K electromagnetic waves on an a x i a l l y magnetized been performed by H i d / 1 / . In t h i s paper we de- . r J plasma column of radins a enclosed in a glass tube

Boyer, Edmond

211

Influence of lateral target size on hot electron production and electromagnetic pulse emission from laser-irradiated metallic targets  

SciTech Connect

The influences of lateral target size on hot electron production and electromagnetic pulse emission from laser interaction with metallic targets have been investigated. Particle-in-cell simulations at high laser intensities show that the yield of hot electrons tends to increase with lateral target size, because the larger surface area reduces the electrostatic field on the target, owing to its expansion along the target surface. At lower laser intensities and longer time scales, experimental data characterizing electromagnetic pulse emission as a function of lateral target size also show target-size effects. Charge separation and a larger target tending to have a lower target potential have both been observed. The increase in radiation strength and downshift in radiation frequency with increasing lateral target size can be interpreted using a simple model of the electrical capacity of the target.

Chen Ziyu; Li Jianfeng; Yu Yong; Li Xiaoya; Peng Qixian; Zhu Wenjun [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Wang Jiaxiang [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

2012-11-15

212

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

PubMed

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 dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models 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. PMID:24291788

Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

2014-01-01

213

OTR measurements and modeling of the electron beam optics at the E-cooling facility  

SciTech Connect

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 {micro}m 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 {micro}s to 4 {micro}s. 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.

Warner, A.; Burov, Alexey V.; Carlson, K.; Kazakevich, G.; Nagaitsev, S.; Prost, L.; Sutherland, M.; Tiunov, M.; /Fermilab /Novosibirsk, IYF

2005-11-01

214

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

215

Low-Temperature Two-Phase Microchannel Cooling for High-Heat-Flux Thermal Management of Defense Electronics  

Microsoft Academic Search

For a given heat sink thermal resistance and ambient temperature, the temperature of an electronic device rises fairly linearly with increasing device heat flux. This relationship is especially problematic for defense electronics, where heat dissipation is projected to exceed 1000 W\\/cm2 in the near future. Direct and indirect low-temperature refrigeration cooling facilitate appreciable reduction in the temperature of both coolant

Jaeseon Lee; Issam Mudawar

2009-01-01

216

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

217

Gamma ray signatures of ultra high energy cosmic ray accelerators: electromagnetic cascade versus synchrotron radiation of secondary electrons  

E-print Network

We discuss the possibility of observing ultra high energy cosmic ray sources inhigh energy gamma rays. Protons propagating away from their accelerators produce secondary electrons during interactions with cosmic microwave background photons. These electrons start an electromagnetic cascade that results in a broad band gamma ray emission. We show that in a magnetized Universe ($B \\gtrsim 10^{-12}$ G) such emission is likely to be too extended to be detected above the diffusebackground. A more promising possibility comes from the detection of synchrotron photons from the extremely energetic secondary electrons. Although this emission is produced in a rather extended region of size $\\sim 10Mpc$, it is expected to be point-like and detectable at GeV energies if the intergalactic magnetic field is at the nanogauss level.

Stefano Gabici; Felix A. Aharonian

2006-10-12

218

Effects of impurity seeding and charge non-neutrality on electromagnetic electron temperature gradient modes in a tokamak  

SciTech Connect

A linear theory of toroidal electromagnetic electron temperature gradient (ETG) mode is reported. The effects such as Debye shielding, impurities, magnetic flutter perturbations {delta}B{sub perpendicular} and compressible parallel magnetic field perturbations {delta}B{sub parallel} are included in a fluid model. An eigenvalue equation is derived and solved analytically in local and semilocal limits. In the nonlocal limit, the eigenvalue equations are solved numerically. A comparison is also made of the linear thresholds obtained from this simple fluid model with previous gyrokinetic simulations. It is shown that the simple fluid theory results compare well with the thresholds obtained from gyrokinetic simulations.

Tangri, Varun; Singh, Raghvendra; Kaw, Predhiman [Institute For Plasma Research, Bhat, Gandhinagar, Gujarat 382 428 (India)

2005-07-15

219

Electron-phonon interaction in heavy fermion compounds. Electromagnetic generation of ultrasonic waves  

NASA Astrophysics Data System (ADS)

Electromagnetic generation of sound in the heavy fermion systems CeRu2Si2 and UPt3 is investigated. Two coupling mechanisms are identified: Grüneisen parameter coupling and Lorentz force coupling. The latter mechanism can be used to determine experimentally the skin effect penetration depth. Some special effects in UPt3 are mentioned.

Hampel, G.; Bruls, G.; Weber, D.; Kouroudis, I.; Lüthi, B.

1990-01-01

220

Electron-phonon interaction in heavy fermion compounds Electromagnetic generation of ultrasonic waves  

Microsoft Academic Search

Electromagnetic generation of sound in the heavy fermion systems CeRu2Si2 and UPt3 is investigated. Two coupling mechanisms are identified: Grüneisen parameter coupling and Lorentz force coupling. The latter mechanism can be used to determine experimentally the skin effect penetration depth. Some special effects in UPt3 are mentioned.

G. Hampel; G. Bruls; D. Weber; I. Kouroudis; B. Lüthi

1989-01-01

221

Electron-phonon interaction in heavy fermion compounds Electromagnetic generation of ultrasonic waves  

NASA Astrophysics Data System (ADS)

Electromagnetic generation of sound in the heavy fermion systems CeRu 2Si 2 and UPt 3 is investigated. Two coupling mechanisms are identified: Grüneisen parameter coupling and Lorentz force coupling. The latter mechanism can be used to determine experimentally the skin effect penetration depth. Some special effects in UPt 3 are mentioned.

Hampel, G.; Bruls, G.; Weber, D.; Kouroudis, I.; Lüthi, B.

1989-10-01

222

Simulation of fluid flow and heat transfer in microchannel cooling for LTCC electronic packages  

Microsoft Academic Search

The hydrodynamic and thermal characteristics of microchannel networks are investigated by finite element analysis with commercial software Fluent. The simulation model is based on fabricated thick film LTCC substrate with 3D cooling microchannels. A comparison of the cooling performance among fractal-shaped microchannel, parallel microchannel, serpentine microchannel, spiral microchannel is also conducted numerically based on the same heat flux and the

J. Zhang; Y. F. Zhang; M. Miao; Y. F. Jin; S. L. Bai; J. Q. Chen

2009-01-01

223

A conduction-cooled, 680-mm-long warm bore, 3-T Nb3Sn solenoid for a Cerenkov free electron laser  

Microsoft Academic Search

A compact, cryocooler cooled Nb3Sn superconducting magnet system for a Cerenkov free electron laser has been designed, fabricated and tested. The magnet is positioned directly behind the electron gun of the laser system. The solenoidal field compresses and guides a tube-shaped 100 A, 500 kV electron beam. A two-stage GM cryocooler, equipped with a first generation ErNi5 regenerator, cools the

W. A. J. Wessel; A. den Ouden; H. J. G. Krooshoop; H. H. J. ten Kate; T. Wieland; P. J. M. van der Slot

1999-01-01

224

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

SciTech Connect

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.

Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi [Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8568 (Japan)

2009-02-15

225

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

SciTech Connect

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.

Fawley, William M; Vay, Jean-Luc

2009-04-29

226

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

227

Large Bandwidth of NbN Phonon-Cooled Hot-Electron Bolometer Mixers on Sapphire Substrates  

Microsoft Academic Search

The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 nm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 j.t wide and 21.1, long, placed between Ti-Au contact pads. To

S. Cherednichenko; P. Yagoubov; K. Il'In; G. Gol'Tsman; E. Gershenzon

1997-01-01

228

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

DOEpatents

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.

Datskos, Panagiotis G. (Knoxville, TN); Rajic, Slobodan (Knoxville, TN); Datskou, Irene C. (Knoxville, TN); Egert, Charles M. (Oak Ridge, TN)

2002-01-01

229

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

E-print Network

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. 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 of 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.

P. O. Kazinski

2013-06-06

230

Self-Focused Electron and Positive-Ion Beams Produced by Heated or Cooled Pyroelectric Crystals in Dilute Gases  

NASA Astrophysics Data System (ADS)

Self-focusing, spatially stable, variable energy electron and positive-ion beams accelerated from LiNbO3 crystal surfaces in dilute gases after the crystal has been heated and returned to room temperature have been observed. A 4 mm dia x 10 mm cylindrical LiNbO3 crystal in <10 mtorr of dry N2 is heated from the + z base to 160^0 C and allowed to cool to room temperature after which spatially-stable electron beams are produced. A ZnS screen was placed at the focal length (16 cm) of the crystal and photographs of the beam spot were taken at different pressures. A 100 ?m surface barrier electron detector was used to determine the maximum electron beam energy (147keV). A similar crystal in 5x10-6 torr of dry N2 when heated from the z base accelerated N_2^+ ions up to 113 keV from the +z base on cooling. The dynamic behavior of the electron beam as pressure changes will be demonstrated on a CD rom and laptop. 1 J.D. Brownridge, S. M. Shafroth, D. Trott, B. Stoner, W. Hooke (Applied Physics Letts, Jan 22,01) 2. J.D. Brownridge, Nature (London) 358, 278 (1992) 3. J.D. Brownridge, and S. Raboy, J. Appl. Phys. 86, 640 (1999)

Brownridge, James; Shafroth, Stephen

2001-04-01

231

Hybrid two-dimensional Monte-Carlo electron transport in self-consistent electromagnetic fields  

Microsoft Academic Search

The physics and numerics of the hybrid electron transport code ANTHEM are described. The need for the hybrid modeling of laser generated electron transport is outlined, and a general overview of the hybrid implementation in ANTHEM is provided. ANTHEM treats the background ions and electrons in a laser target as coupled fluid components moving relative to a fixed Eulerian mesh.

R. J. Mason; C. W. Cranfill

1985-01-01

232

Novel approaches for the characterization of electromagnetic fields using electron Takeshi Kasama1,2  

E-print Network

to be transferred between the TEM specimen holder and a scanning electron microscope (SEM), a focused ion beam (FIB of up to ±70° with voltages applied to them in situ in the electron microscope. The second relates and electrostatic fields in materials in the transmission electron microscope (TEM) at a spatial resolution that can

Dunin-Borkowski, Rafal E.

233

The theoretical study on electronic structure and electromagnetic properties of ?-MnO2 based on crystal defects  

NASA Astrophysics Data System (ADS)

First-principles calculations based on density functional theory (DFT) have been carried out to investigate the effects of crystal defects (intrinsic vacancy defects and ion doping) on the microwave dielectric response and the correlative electromagnetic properties of ?-MnO2 systematically. The possible role of crystal defects in electromagnetic performance is studied utilizing density of states (DOS) and the bond length between the manganese and oxygen. Lattice distortion is induced by the introduction of crystal defects. The spin-electronic DOS demonstrates that Ni doping enhances the spin-polarization of MnO2, which indicates that the Ni-doped MnO2 possesses certain magnetic characteristic, which is helpful for magnetic loss. The emergence of a new defect mode, contributes to the relaxation polarization phenomenon, so as to enhance the dielectric loss ability. In addition, through the change of the bond length and pseudo gap width, it can be learned that the bond strength and covalency of Mn-O bonds are weakened, which increases the dielectric loss of MnO2. The results throw light on the exploration of theoretical research on the microwave absorbing properties of MnO2 with crystal defects.

Duan, Yuping; Chen, Junlei; Zhang, Yahong; Wang, Tongmin

2014-12-01

234

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

NASA Astrophysics Data System (ADS)

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.

Yurik, Roman; Tereshchenko, Evgeny; Baddeley, Lisa

235

Particle-in-cell simulations of velocity scattering of an anisotropic electron beam by electrostatic and electromagnetic instabilities  

SciTech Connect

The velocity space scattering of an anisotropic electron beam (T{sub ?b}/T{sub ?b}>1) flowing along a background magnetic field B{sub 0} through a cold plasma is investigated using both linear theory and 2D particle-in-cell simulations. Here, ? and ? represent the directions perpendicular and parallel to B{sub 0}, respectively. In this scenario, we find that two primary instabilities contribute to the scattering in electron pitch angle: an electrostatic electron beam instability and a predominantly parallel-propagating electromagnetic whistler anisotropy instability. Our results show that at relative beam densities n{sub b}/n{sub e}?0.05 and beam temperature anisotropies T{sub b?}/T{sub b?}?25, the electrostatic beam instability grows much faster than the whistler instabilities for a reasonably fast hot beam. The enhanced fluctuating fields from the beam instability scatter the beam electrons, slowing their average speed and increasing their parallel temperature, thereby increasing their pitch angles. In an inhomogeneous magnetic field, such as the geomagnetic field, this could result in beam electrons scattered out of the loss cone. After saturation of the electrostatic instability, the parallel-propagating whistler anisotropy instability shows appreciable growth, provided that the beam density and late-time anisotropy are sufficiently large. Although the whistler anisotropy instability acts to pitch-angle scatter the electrons, reducing perpendicular energy in favor of parallel energy, these changes are weak compared to the pitch-angle increases resulting from the deceleration of the beam due to the electrostatic instability.

Fu, X. R., E-mail: xrfu@lanl.gov; Cowee, M. M.; Winske, D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Liu, K. [Auburn University, Auburn, Alabama 36849 (United States)] [Auburn University, Auburn, Alabama 36849 (United States); Peter Gary, S. [Space Science Institute, Boulder, Colorado 80301 (United States)] [Space Science Institute, Boulder, Colorado 80301 (United States)

2014-04-15

236

Relativistic electron precipitation events driven by electromagnetic ion-cyclotron waves  

SciTech Connect

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.

Khazanov, G., E-mail: george.v.khazanov@nasa.gov; Sibeck, D. [NASA Goddard Space FlightCenter, Greenbelt, Maryland 20771 (United States); Tel'nikhin, A.; Kronberg, T. [Department of Physics and Technology, Altai State University, Barnaul (Russian Federation)

2014-08-15

237

Thermal optimisation of mechatronically integrated power electronics for an engine cooling fan using brushless technology  

Microsoft Academic Search

Mechatronical integration of power and control electronics directly into the actuators offers many advantages such as reduced costs, increased EMC, reduced volume or less weight. However mechatronical integration often is accompanied with undesired increase of thermal or mechanical loading of electronics. Computer-aided thermal\\/mechanical modelling and cosimulation of electronic housings for control and power electronics lead to optimised design of a

Th. Kaiser; W. Staiger; R. Orthmann; D. George; P. Huebner

2000-01-01

238

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

SciTech Connect

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.

Bulanov, Sergei V.; Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Bulanov, Stepan S. [University of California, Berkeley, California 94720 (United States)

2011-11-15

239

Optimization of electron beam—electromagnetic field interaction in multiwave Cerenkov generators  

NASA Astrophysics Data System (ADS)

In the paper, an overview of investigation results of three-centimeter wavelength range multiwave Cerenkov generators (MWCG) with different slow-wave structure (SWS) geometry is presented. Theoretical and experimental investigations of MWCG with a two-sectional SWS allowed to distinguish several generation regimes due to nonlinear interaction of TM01-mode longitudinal resonances. It is shown that the use of SWS with nonuniform sections allows to increase generation efficiency, to expand the region of parameters for stable generation, to reduce the influence of the gap between the beam and SWS on the output power, to narrow radiation spectrum. We associate further progress with development of new methods to control spatial-temporal topology of electromagnetic field in overmoded sectionalized SWS.

Koshelev, V. I.; Deichuly, M. P.

1999-05-01

240

Electronic tuning of magnetic permeability in Co2Z hexaferrite toward high frequency electromagnetic device miniaturization  

NASA Astrophysics Data System (ADS)

The magnetic and magnetostriction properties of Z-type cobalt-doped barium hexaferrite with perpendicular c-axis crystallographic texture are presented. The hexaferrite was utilized as a component in Co2Z/lead magnesium niobate-lead titanate multiferroic heterostructures whose tunability of permeability with electric field in terms of ferromagnetic resonance shift was supported by experiments and theoretical calculation. A permeability change of 16% was measured by an induced magnetic field of 38 Oe under the application of 6 kV/cm of electric field. These findings lay the foundation for the application of Z-type hexaferrites in tunable rf and microwave devices valued for sending, receiving, and manipulating electromagnetic signals.

Chen, Yajie; Daigle, Andrew; Fitchorov, Trifon; Hu, Bolin; Geiler, Michael; Geiler, Anton; Vittoria, C.; Harris, V. G.

2011-05-01

241

Numerical calculation of dynamical friction in electron cooling systems, including magnetic field perturbations and finite time effects  

SciTech Connect

The orders-of-magnitude higher luminosities required by future electron-ion collider concepts require a dissipative force to counteract the numerous factors acting to gradually increase the phase space volume of relativistic ion beams. High-energy electron cooling systems could provide the necessary dissipation via dynamical friction, but will have to be designed for new parameter regimes. It is expected that magnetic field errors, finite interaction time and other effects will reduce the dynamical friction and hence increase the cooling time, so improved understanding of the underlying dynamics is important. We present a generalized form of the classical field-free friction force equation, which conveniently captures some of these effects. Previous work (Bell et al 2008 J. Comput. Phys. 227 8714) shows both numerical and conceptual subtleties associated with undersampling of strong collisions, and we present a rigorous mathematical treatment of such difficulties, based on the use of a modified Pareto distribution for the electron-ion impact parameters. We also present a very efficient numerical algorithm for calculating the dynamical friction on a single ion in the field free case. For the case of arbitrary magnetic field errors, we present numerical simulation results, showing agreement with our generalized friction force formula.

Sobol, A.V.; Fedotov, A.; Bruhwiler, D.L.; Bell, G.I.; Litvinenko, V.

2010-09-24

242

Integrated three-dimensional module heat exchanger for power electronics cooling  

DOEpatents

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.

Bennion, Kevin; Lustbader, Jason

2013-09-24

243

Hybrid Liquid Immersion and Synthetic Jet Heat Sink for Cooling 3-D Stacked Electronics  

Microsoft Academic Search

This paper focuses on the design and parametric numerical study of a hybrid heat sink combining a liquid thermal interface with an array of synthetic jet actuators for 3-D chip stack cooling. The air-side heat sink exploits enhanced localized heat transfer achieved via a central array of synthetic jet actuators. The key focus of this paper is the numerical simulation

Krishna Kota; Pablo Hidalgo; Yogendra Joshi; Ari Glezer

2012-01-01

244

Narrow channel heat sink for cooling of high powered electronic components  

Microsoft Academic Search

The authors show the results of narrow channel heat sinks used for cooling of high powered components. The results of the experimental simulation for various air delivery methods are reported. The results show the difference in the thermal performance of the heat sink with top clearance versus ducted systems. In addition, effects of component layout power variation and air velocity

K. Azar; R. S. McLeod; R. E. Caron

1992-01-01

245

Televisions, Video Privacy, and Powerline Electromagnetic Interference  

E-print Network

Televisions, Video Privacy, and Powerline Electromagnetic Interference Miro Enev University that the power supplies of modern TVs produce discernible electromagnetic interference (EMI) signatures security, electromagnetic in- terference 1. INTRODUCTION It is known that consumer electronic devices can

Matsuoka, Yoky

246

New acceleration mechanism of electrons by an electromagnetic wave in a weakly magnetized plasma  

Microsoft Academic Search

The axial distribution of maximum energy of electrons accelerated by an EM wave in a weakly magnetized inhomogeneous Ar plasma is determined experimentally using a 10-Hz pulse discharge in a 1-m-long 60-cm-diameter chamber at pressure 300-400 microtorr with an 11-G external magnetic field. Plasma parameters include maximum density 2 x 10 to the 11th\\/cu cm, electron temperature 2.5-3 eV, and

Y. Nishida; M. Yoshizumi; R. Sugihara

1984-01-01

247

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

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, ?(s,2) and ?(s,3), were determined for four types of CuO nanoparticles. The ?(s,2) value was almost independent of the type of nanoparticle, whereas the ?(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. PMID:25382043

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

2014-01-01

248

In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap  

E-print Network

We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning-Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for measurement of the static magnetic field and the microwave electric field in the trap. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially-resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen.

C. Amole; M. D. Ashkezari; M. Baquero-Ruiz; W. Bertsche; E. Butler; A. Capra; C. L. Cesar; M. Charlton; A. Deller; N. Evetts; S. Eriksson; J. Fajans; T. Friesen; M. C. Fujiwara; D. R. Gill; A. Gutierrez; J. S. Hangst; W. N. Hardy; M. E. Hayden; C. A. Isaac; S. Jonsell; L. Kurchaninov; A. Little; N. Madsen; J. T. K. McKenna; S. Menary; S. C. Napoli; K. Olchanski; A. Olin; P. Pusa; C. Ø. Rasmussen; F. Robicheaux; E. Sarid; D. M. Silveira; C. So; S. Stracka; T. Tharp; R. I. Thompson; D. P. van der Werf; J. S. Wurtele

2014-05-04

249

In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap  

E-print Network

We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning-Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for measurement of the static magnetic field and the microwave electric field in the trap. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially-resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen.

Amole, C; Baquero-Ruiz, M; Bertsche, W; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Evetts, N; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Stracka, S; Tharp, T; Thompson, R I; van der Werf, D P; Wurtele, J S

2014-01-01

250

Direct Liquid Cooling of High Flux Micro and Nano Electronic Components  

Microsoft Academic Search

The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1 =kW\\/cm2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical thermal

Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

2006-01-01

251

Electromagnetically pumped free-electron laser in the scheme of separate interaction space from pump wave generator  

NASA Astrophysics Data System (ADS)

The theory of an electromagnetically pumped free-electron laser in the scheme of a separate interaction space from the pump wave generator is developed, taking into account the transverse inhomogeneity of incident and scattered waves, and the presence of a magnetic field of 20 kG focusing the particles. The nonlinear computation results, including the coupling coefficients, the excitation curves, powers and efficiency, etc., are obtained on a set of input parameters of our recently established accelerator and FEL system with a pulse high-current relativistic electron beam (600 kV, 3 kA, 70 ns). An experiment is demonstrated in which the relativistic backward wave corrugation oscillator provides a TM(sub 01) pump wave with the power of 100 MW at 3 cm wavelength and connects with a smooth tube interaction section to produce stimulated scattering radiation with integral power of 1 MW at 3-8 mm wavelengths. Also, the numerical and the measured results are compared and discussed.

Deng, Tianquan; Zhu, Hui; Liang, Zheng

1994-03-01

252

Electromagnetic Radiation: On Trial  

NSDL National Science Digital Library

This activity introduces students to the properties of electromagnetic radiation in a variety of ways. For example, they put the different types of the electromagnetic radiation on trial, selecting the judge, prosecutor, defense counsel, and jury, and learning about electromagnetic energy by arguing the pros and cons of each wavelength. During this activity, students are introduced to the general properties of electromagnetic waves, learn to analyze the relation between the specific properties of waves and their position in the electromagnetic spectrum, and discuss methods used to detect and analyze different waves. Students also learn about scientists whose work contributed to our understanding of electromagnetic energy. Students are encouraged to use an electronic bulletin board to communicate with each other, posting insights, ideas, evidence and questions on electromagnetic energy.

253

Influence of the Electromagnetic Environment on the Accuracy of the Single Electron Pump  

Microsoft Academic Search

We consider the 3-junction single electron pump with on-chip resistors (R-pump) driven by harmonic gates. We calculate the cotunneling error of the device as a function of the external resistance. It is shown that for suitable values of the parameters metrological accuracy can be achieved.

Vladimir Bubanja

2002-01-01

254

Heat Pipe Integrated in Direct Bonded Copper (DBC) Technology for Cooling of Power Electronics Packaging  

Microsoft Academic Search

Thermal dissipation in power electronics systems is becoming an extremely important issue with the continuous growth of power density in their components. The primary cause of failure in this equipment is excessive temperatures in the critical components, such as semiconductors and transformers. This problem is particularly important in power electronic systems for space applications. These systems are usually housed in

Mariya Ivanova; Yvan Avenas; Christian Schaeffer; Jean-Bernard Dezord; Juergen Schulz-Harder

2006-01-01

255

Low-noise electromagnetic {delta}f particle-in-cell simulation of electron Bernstein waves  

SciTech Connect

The conversion of the extraordinary (X) mode to an electron Bernstein wave (EBW) is one way to get rf energy into an overdense plasma. Analysis of this is complex, as the EBW is a fully kinetic wave, and so its linear propagation is described by an intractable integro-differential equation. Nonlinear effects cannot be calculated within this rubric at all. Full particle-in-cell (PIC) simulations cannot be used for these analyses, as the noise levels for reasonable simulation parameters are much greater than the typical rf amplitudes. It is shown that the delta-f computations are effective for this analysis. In particular, the accuracy of those computations has been verified by comparison with full PIC, cold plasma theory, and small gyroradius theory. This computational method is then used to analyze mode conversion in different frequency regimes. In particular, reasonable agreement with the theoretical predictions of Ram and Schultz [Phys. Plasmas 7, 4084 (2000)] in the linear regime is found, where 100% X-B mode conversion has been obtained when the driving frequency is less than twice the electron gyrofrequency. The results show that cold-plasma theory well predicts the mode conversion efficiency, as is consistent with the phase-space picture of mode conversion. From this it can be shown that nearly 100% X-B mode conversion cannot be obtained when the frequency is higher than the electron second harmonic cyclotron frequency.

Xiang Nong; Cary, John R.; Barnes, Daniel C.; Carlsson, John [Center for Integrated Plasma Studies, University of Colorado at Boulder, Boulder, Colorado 80309 (United States); Tech-X Corporation, 5621 Arapahoe Avenue, Suite A, Boulder, Colorado 80303 (United States)

2006-06-15

256

Rotational cooling of heteronuclear molecular ions with {sup 1}{sigma}, {sup 2}{sigma}, {sup 3}{sigma}, and {sup 2}{pi} electronic ground states  

SciTech Connect

The translational motion of molecular ions can be effectively cooled sympathetically to translational temperatures below 100 mK in ion traps through Coulomb interactions with laser-cooled atomic ions. The rovibrational degrees of freedom, however, are expected to be largely unaffected during translational cooling. We have previously proposed schemes for cooling of the internal degrees of freedom of such translationally cold but internally hot heteronuclear diatomic ions in the simplest case of {sup 1}{sigma} electronic ground-state molecules. Here we present a significant simplification of these schemes and make a generalization to the most frequently encountered electronic ground states of heteronuclear molecular ions: {sup 1}{sigma}, {sup 2}{sigma}, {sup 3}{sigma}, and {sup 2}{pi}. The schemes are relying on one or two laser-driven transitions with the possible inclusion of a tailored incoherent far-infrared radiation field.

Vogelius, I.S.; Madsen, L.B.; Drewsen, M. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark); Danish National Research Foundation Center for Quantum Optics and Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)

2004-11-01

257

Cooled Transmission-Mode NEA-Photocathode with a Band-Graded Active Layer for High Brightness Electron Source  

SciTech Connect

A Free-Electron Laser (FEL) places many exacting demands on a Negative Electron Affinity (NEA) photocathode, such as the need for an ultra-fast response time, low energy spread for emitted electrons, high quantum efficiency (Q.E.) and a high average photocurrent. However, these key requirements are conflicting, and cannot be fulfilled by conventional photocathode design. For example, to achieve {approx}10 ps response time, the photocathode active layer should be thinned to {approx}100-150 nm, but this thickness is insufficient to provide near-complete absorption of light with hv{approx_equal}{epsilon}{sub g} so high Q.E. cannot be achieved. Complete optical absorption and high Q.E. can be obtained using a thin active layer at higher photon energies, but this generates photoelectrons with excess kinetic energy within the semiconductor. These photoelectrons do not thermalise in a thin active layer, so yield a broad energy distribution in the emitted electrons. Moreover, cooling of the conventional semiconductor photocathode structure is ineffective due to its fragility, so it cannot be pressed firmly to a heat sink to attain good thermal contact. Consequently, the maximum CW photocurrent is limited to a few miiliamps. The goal of our work is to develop a new design of NEA-photocathode which is optimised for FEL applications.

Jones, L. B.; Militsyn, B. L.; Smith, S. L. [STFC Daresbury Laboratory, Warrington, WA4 4AD (United Kingdom); Rozhkov, S. A. [Novosibirsk State University, Novosibirsk, 630090 (Russian Federation); Bakin, V. V.; Kosolobov, S. N.; Scheibler, H. E. [Institute of Semiconductor Physics, Novosibirsk, 630090 (Russian Federation); Terekhov, A. S. [Novosibirsk State University, Novosibirsk, 630090 (Russian Federation); Institute of Semiconductor Physics, Novosibirsk, 630090 (Russian Federation)

2009-08-04

258

Electromagnetic formulation of global gyrokinetic particle simulation in toroidal geometry  

E-print Network

Electromagnetic formulation of global gyrokinetic particle simulation in toroidal geometry I. Holod online 9 December 2009 The fluid-kinetic hybrid electron model for global electromagnetic gyrokinetic the capabilities to describe low frequency processes in electromagnetic turbulence with electron dynamics

Lin, Zhihong

259

Toward sub-Kelvin resistive cooling and non destructive detection of trapped non-neutral electron plasma  

NASA Astrophysics Data System (ADS)

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 ?W corresponding to a drain current in the range 100–800 ? A. An additional contribution due to the gate noise has been identified when the drain current is below 300 ?A 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.

Di Domizio, S.; Krasnický, D.; Lagomarsino, V.; Testera, G.; Vaccarone, R.; Zavatarelli, S.

2015-01-01

260

Electromagnetic envelope solitons in ultrarelativistic inhomogeneous electron-positron-ion plasma  

NASA Astrophysics Data System (ADS)

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.

Du, Hong-E.; Cheng, Li-Hong; Yu, Zi-Fa; Xue, Ju-Kui

2014-08-01

261

Electromagnetic envelope solitons in ultrarelativistic inhomogeneous electron-positron-ion plasma  

SciTech Connect

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.

Du, Hong-E; Cheng, Li-Hong; Yu, Zi-Fa; Xue, Ju-Kui, E-mail: xuejk@nwnu.edu.cn [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070 (China)

2014-08-15

262

The cooling of particle beams  

SciTech Connect

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.

Sessler, A.M.

1994-10-01

263

Neutrinos from SN 1987A - Implications for cooling of the nascent neutron star and the mass of the electron antineutrino  

NASA Technical Reports Server (NTRS)

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.

Loredo, Thomas J.; Lamb, Don Q.

1989-01-01

264

The interplay of Kappa and core populations in the solar wind: Electromagnetic electron cyclotron instability  

NASA Astrophysics Data System (ADS)

Recently, a realistic parameterization was proposed for the kinetic anisotropy and the resulting instabilities in the solar wind plasma. This parameterization is based on observations of the particle velocity distribution, which always comprises a Maxwellian population at low energies, viz. the core, and a suprathermal halo in the tail of the distribution which is best described by the Kappa (power law) models. The cyclotron instability, driven by an anisotropic electron halo, was found to be inhibited by the finite thermal spread in the core, and this effect is highly dependent on the halo-core relative density. In this paper, the interplay between the Kappa and Maxwellian populations is further investigated for more complex (less idealized) situations when both the core and halo temperatures are anisotropic. Growth of this instability is markedly stimulated by the core anisotropy. The wave numbers that are stable for an isotropic core become unstable even for small anisotropies of this population. Just a modest increase of the core anisotropy from Ac=T?/T?=1.2 to 2 causes the growth rates to enhance by 1 order of magnitude, and the range of unstable wave numbers to extend considerably. When the anisotropies in the core and halo are comparable, the growth rate exhibits two distinct peaks, the first driven by the halo at lower wave numbers and the second driven by the core. However, the first peak is inhibited by the suprathermal populations, while the second peak is sustained, suggesting a more intricate connection between the core and Kappa populations.

Lazar, M.; Poedts, S.; Schlickeiser, R.

2014-12-01

265

Microslots : scalable electromagnetic instrumentation  

E-print Network

This thesis explores spin manipulation, fabrication techniques and boundary conditions of electromagnetism to bridge the macroscopic and microscopic worlds of biology, chemistry and electronics. This work is centered around ...

Maguire, Yael G., 1975-

2004-01-01

266

Modeling of thermal via heat transfer performance for power electronics cooling  

Microsoft Academic Search

For power electronics and Light Emitting Diode (LED) lighting applications, thermal management represents a critical factor having important consequences on electrical performance and overall cost of the assembly. Although advanced solutions for heat removal like Isolated Metal Substrates (IMS) base materials or thermally conductive epoxies have entered the market for a few years they still have a high price tag

Catalin Negrea; Paul Svasta

2011-01-01

267

"Do Type III-associated escaping electron beams cool the corona?"  

NASA Astrophysics Data System (ADS)

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.

Saint-Hilaire, P.; Wang, L.; Vilmer, N.; Kerdraon, A.

2012-12-01

268

A modified Bitter-type electromagnet and control system for cold atom experiments  

SciTech Connect

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}.

Luan, Tian; Zhou, Tianwei; Chen, Xuzong, E-mail: xuzongchen@pku.edu.cn [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)] [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Ma, Zhaoyuan, E-mail: zyma@siom.cas.cn [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)] [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2014-02-15

269

The enhancement effect in K-shell radiative recombination of familyseries Ufamilyseriesfontsize{10{12selectfont 92+}} ions with cooling electrons  

NASA Astrophysics Data System (ADS)

We report the results of the x-ray radiative recombination (RR) experiment at the electron cooler of the ESR storage ring performed, for the first time, for detuned (off-cooling) electron energies. In this experiment the recombination of stored, decelerated bare uranium ions with electrons in the energy range 0-1000 meV was studied by observing K-RR x-ray photons emitted from direct radiative recombination to the lowest n=1 state. In this way the RR process was studied in a state selective manner for several off-cooling electron energies. The measured dependency of the recombination rate on the relative electron energies for K-shell RR x-ray photons are compared with the predictions of both nonrelativistic and fully relativistic calculations for the radiative recombination. A role of the relativistic effects, which contribute substantially for higher relative electron energies, are discussed. Strong enhancement of the recombination rate is observed for the the zero relative electron energy (cooling condition) for the K-shell.

Bana?, D.; Pajek, M.; Stöhlker, Th.; Beyer, H. F.; Böhm, S.; Bosch, F.; Brandau, C.; Czarnota, M.; Chatterjee, S.; Dousse, J.-Cl.; Fritzsche, S.; Gumberidze, A.; Hagmann, S.; Kozhuharov, C.; Kumar, A.; Liesen, D.; Mokler, P. H.; Müller, A.; Reuschl, R.; Schmidt, E. W.; Sierpowski, D.; Spillmann, U.; Surzhykov, A.; Szlachetko, J.; Tashenov, S.; Trotsenko, S.; Verma, P.; Warczak, A.

2009-03-01

270

Measuring the electron electric dipole moment using laser-cooled cesium atoms in optical lattices  

NASA Astrophysics Data System (ADS)

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 Transmission Electron Microscopy (STEM); Matrix assisted laser desorption ionization/time of flight (MALDI-TOF), X-ray diffraction (XRD), Scanning Tunneling microscopy (STM); while catalytic activity was determined by diffuse reflectance infrared Fourier Transform Spectroscopy (DRIFTS), High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC).

Zhu, Kunyan

271

Hot-electron cooling by acoustic and optical phonons in monolayers of MoS2 and other transition-metal dichalcogenides  

NASA Astrophysics Data System (ADS)

We study hot-electron cooling by acoustic and optical phonons in monolayer MoS2. The cooling power P (Pe=P /n ) is investigated as a function of electron temperature Te (0-500 K) and carrier density n (1010-1013 cm-2) taking into account all relevant electron-phonon (el-ph) couplings. We find that the crossover from acoustic phonon dominated cooling at low Te to optical phonon dominated cooling at higher Te takes place at Te˜50 -75 K. The unscreened deformation potential (DP) coupling to the TA phonon is shown to dominate P due to acoustic phonon scattering over the entire temperature and density range considered. The cooling power due to screened DP coupling to the LA phonon and screened piezoelectric (PE) coupling to the TA and LA phonons is orders of magnitude lower. In the Bloch-Grüneisen (BG) regime, P ˜Te4(Te6) is predicted for unscreened (screened) el-ph interaction and P ˜n-1 /2(Pe˜n-3 /2) for both unscreened and screened el-ph interaction. The cooling power due to optical phonons is dominated by zero-order DP couplings and the Fröhlich interaction, and is found to be significantly reduced by the hot-phonon effect when the phonon relaxation time due to phonon-phonon scattering is large compared to the relaxation time due to el-ph scattering. The Te and n dependence of the hot-phonon distribution function is also studied. Our results for monolayer MoS2 are compared with those in conventional two-dimensional electron gases (2DEGs) as well as monolayer and bilayer graphene.

Kaasbjerg, Kristen; Bhargavi, K. S.; Kubakaddi, S. S.

2014-10-01

272

Dynamical arrest of electron transfer reorganization in super-cooled water.  

PubMed

This paper reports the results of Molecular Dynamics (MD) simulations of the solvent reorganization energy of electron transfer (ET) reactions in low-temperature solvents. Simulations are carried out for a model charge-transfer optical dye (p-nitroaniline) in SPC/E water in a range of temperatures down to the point of solvent ideal glass transition. We show a significant departure of the solvent reorganization energy, measured on a given time window, from its thermodynamic limit obtained by averaging over long simulation trajectories. Our results thus indicate that optical solvatochromism and activation parameters of ET reactions measured in viscous solvents will be significantly affected by the dynamical arrest of nuclear solvation when the experimental time scale becomes comparable to the characteristic relaxation time of the solvent. PMID:16305214

Ghorai, Pradip K; Matyushov, Dmitry V

2005-11-30

273

PHYSICS 417. Electromagnetism. Lecturer: Tim Gorringe.  

E-print Network

PHYSICS 417. Electromagnetism. Lecturer: Tim Gorringe. Office: CP273. Phone: 257-8740. Textbook: Electromagnetic Fields, R. Wangsness, 2nd Ed. Web page www.pa.uky.edu/gorringe/phy417/index.html Class hours: MWF-semester sequence on electromagnetic theory. 1 Course Objectives. The electromagnetic field binds electrons

MacAdam, Keith

274

PHYSICS 416. Electromagnetism. Lecturer: Tim Gorringe.  

E-print Network

PHYSICS 416. Electromagnetism. Lecturer: Tim Gorringe. Office: CP 273. Phone: 257-8740. Textbook: Electromagnetic Fields, R. Wangsness, 2nd Ed. Web page www.pa.uky.edu/gorringe/phy416/index.html Class hours: MWF-semester sequence on electromagnetic theory. 1 416/417 Course Objectives. The electromagnetic field binds electrons

MacAdam, Keith

275

Doubling of sensitivity and bandwidth in phonon-cooled hot-electron bolometer mixers  

NASA Astrophysics Data System (ADS)

NbN hot electron bolometer (HEB) mixers are at this moment the best heterodyne detectors for frequencies above 1 THz. However, the fabrication procedure of these devices is such that the quality of the interface between the NbN superconducting film and the contact structure is not under good control. This results in a contact resistance between the NbN bolometer and the contact pad. We compare identical bolometers, with different NbN - contact pad interfaces, coupled with a spiral antenna. We find that cleaning the NbN interface and adding a thin additional superconductor prior to the gold contact deposition improves the noise temperature and the bandwidth of the HEB mixers with more than a factor of 2. We obtain a DSB noise temperature of 950 K at 2.5 THz and a Gain bandwidth of 5-6 GHz. For use in real receiver systems we design small volume (0.15x1 micron) HEB mixers with a twin slot antenna. We find that these mixers combine good sensitivity (900 K at 1.6 THz) with low LO power requirement, which is 160 - 240 nW at the Si lens of the mixer. This value is larger than expected from the isothermal technique and the known losses in the lens by a factor of 3-3.5.

Baselmans, Jochem J. A.; Hajenius, Merlijn; Gao, Jianrong; Korte, Piet d.; Klapwijk, Teun M.; Voronov, Boris; Gol'tsman, Gregory

2004-10-01

276

Modelling of electromagnetic shielding structures for radiated EMI analysis.  

E-print Network

??Electromagnetic (EM) shielding has been used extensively in electronic products to reduce the radiated electromagnetic interference (EMI) from high-speed digital circuits so that the products… (more)

Wang, Zheng.

2008-01-01

277

Influence of the photonuclear effect on electron-neutrino-induced electromagnetic cascades under the Landau-Pomeranchuk-Migdal regime in standard rock  

E-print Network

The observation of earth skimming neutrinos has been proposed as a rather sensitive method to detect ultra-high energy (UHE) cosmic neutrinos. Energetic cosmic neutrinos can interact inside the rock and produce leptons via a charged current interaction. In the case of an incoming electron neutrino undergoing a charged current interaction, the produced UHE electron will induce an underground electromagnetic shower. At high energy (above 7.7 TeV in standard rock), such showers are subject to LPM (Landau, Pomeranchuk and Migdal) suppression of the radiative processes cross sections (bremsstrahlung and pair production). The consequence of this suppression is that showers are elongated. This effect will increase the detection probability of such events allowing deeper showers to emerge with detectable energies. On the other hand, the photonuclear processes which are usually neglected in electromagnetic showers with respect to radiative processes, turn out to become dominant in the LPM regime and will reduce the shower length. In this work, we have performed a complete Monte Carlo study of an underground shower induced by UHE electrons by taking into account both the LPM suppression and the photonuclear interaction. We will discuss the effects of both of these processes on the shower length and on the detectability of such events by ground arrays or fluorescence telescopes. We show that limits on neutrino fluxes that were obtained using simulations that were obviously neglecting photonuclear processes are overoptimistic and should be corrected.

Mathieu Tartare; Didier Lebrun; François Montanet

2012-11-29

278

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)

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

Samimi, A.; Scales, W.; Cruz, M.; Isham, B.; Bernhardt, P. A.

2012-12-01

279

GERA computer code for calculation of two-dimensional electromagnetic fields in resonators and electron-optical systems by the finite element method  

NASA Astrophysics Data System (ADS)

The GERA computer code designed for the computation of 2-D electromagnetic fields in resonators and electron-optical systems by the finite element method is described. Tetragonal and partial quadratic subparametric finite elements are used. The algebraic part of the program is realized on the basis of the program complex of the nonlinear algebra, which allows solution of the system of linear equations and analysis of the spectral composition of 10000 order matrices by direct methods using external memory. The results of numerical experiments are presented.

Khapalov, S. A.

280

Experimental investigation of dissociation pathways of cooled HeH{sup +} following valence electron excitation at 32 nm by intense free-electron-laser radiation  

SciTech Connect

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.

Pedersen, H. B.; Lammich, L. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Domesle, C.; Jordon-Thaden, B.; Ullrich, J.; Wolf, A. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Heber, O. [Department of Particle Physics, Weizmann Institute of Science, 76100 Rehovot (Israel); Treusch, R.; Guerassimova, N. [Hamburger Synchrotronstrahlungslabor at Deutsches Elektronen-Synchrotron, D-22607 Hamburg (Germany)

2010-08-15

281

Refrigerant directly cooled capacitors  

DOEpatents

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.

Hsu, John S. (Oak Ridge, TN); Seiber, Larry E. (Oak Ridge, TN); Marlino, Laura D. (Oak Ridge, TN); Ayers, Curtis W. (Kingston, TN)

2007-09-11

282

Electromagnetic fasteners  

Microsoft Academic Search

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

Randolph W. Crane; Donna J. Marts

1994-01-01

283

Zero-field detection of spin dependent recombination with direct observation of electron nuclear hyperfine interactions in the absence of an oscillating electromagnetic field  

NASA Astrophysics Data System (ADS)

Electrically detected magnetic resonance (EDMR) involves the electron paramagnetic resonance (EPR) study of spin dependent transport mechanisms such as spin dependent tunneling and spin dependent recombination (SDR) in solid state electronics. Conventional EPR measurements generally require strong static magnetic fields, typically 3 kG or greater, and high frequency oscillating electromagnetic fields, typically 9 GHz or higher. In this study, we directly demonstrate that, in the absence of the oscillating electromagnetic field, a very large SDR response (?1%) can be detected at zero magnetic field with associated hyperfine interactions at extremely low magnetic fields in a silicon carbide (SiC) diode at room temperature. The zero-field SDR (ZFSDR) response that we detect is unexpected in the conventional detection scheme of SDR via EDMR. We believe that our observations provide fundamental physical understanding of other recently reported zero-field phenomena such as singlet triplet mixing in double quantum dots and low-field giant magnetoresistance in organic semiconductors. Our work provides an unambiguous demonstration that the zero-field phenomenon we observe involves SDR. Measurements reported herein indicate that extremely useful low-field SDR and ZFSDR results can be acquired simply and inexpensively in systems of technological importance. This work also suggests the potential use of this new physics in applications including absolute magnetometry with self-calibration, spin based memories, quantum computation, and inexpensive low-field EDMR spectrometers for wafer/probing stations.

Cochrane, C. J.; Lenahan, P. M.

2012-12-01

284

Solutions of nonlinear equation of the curvilinear electromagnetic wave theory for point and non-point electron  

Microsoft Academic Search

In previous paper we have shown that there is a special kind of nonlinear\\u000aelectrodynamics - Curvilinear Wave Electrodynamics (CWED), whose equations are\\u000amathematically equivalent to the equations of quantum electrodynamics. The\\u000apurpose of the present paper is to show that in framework of CWED the known\\u000asolutions of the nonlinear electromagnetic equations can be considered as the\\u000aapproximate solutions

Alexander G. Kyriakos

2005-01-01

285

Dual electronic tunability of the dispersion characteristics of electromagnetic-spin waves in high-anisotropic layered multiferroic structures  

NASA Astrophysics Data System (ADS)

Electric and magnetic tuning of phase, frequency, and delay time of electromagnetic-spin waves in thin-film layered multiferroic structure (metal-dielectric gap-ferroelectric material-hexaferrite-dielectric substrate) is numerically simulated. The results are used to demonstrate prospects for application of layered multiferroic hexaferrite-ferroelectric structures in the construction of basically new devices for generation and processing of microwave signals under dual (electric and magnetic) tuning of the working characteristics in the subterahertz frequency range.

Sultanov, R. A.; Grigoryeva, N. Yu.; Kalinikos, B. A.

2014-11-01

286

Cooling performance of a variable speed CO 2 cycle with an electronic expansion valve and internal heat exchanger  

Microsoft Academic Search

The cooling performance of a CO2 cycle must be improved to develop a competitive air-conditioning system with the conventional air-conditioners using HFCs. In this study, the cooling performance of a variable speed CO2 cycle was measured and analyzed by varying the refrigerant charge amount, compressor frequency, EEV opening, and length of an internal heat exchanger (IHX). The basic CO2 system

Honghyun Cho; Changgi Ryu; Yongchan Kim

2007-01-01

287

All-optical NMR in semiconductors provided by resonant cooling of nuclear spins interacting with electrons in the resonant spin amplification regime  

NASA Astrophysics Data System (ADS)

Resonant cooling of different nuclear isotopes manifested in optically induced nuclear magnetic resonances (NMR) is observed in n-doped CdTe/(Cd,Mg)Te and ZnSe/(Zn,Mg)Se quantum wells and for donor-bound electrons in ZnSe:F and GaAs epilayers. By time-resolved Kerr rotation used in the regime of resonant spin amplification, we can expand the range of magnetic fields where the effect can be observed up to nuclear Larmor frequencies of 170 kHz. The mechanism of the resonant cooling of the nuclear spin system is analyzed theoretically. The developed approach allows us to model the resonant spin amplification signals with NMR features.

Zhukov, E. A.; Greilich, A.; Yakovlev, D. R.; Kavokin, K. V.; Yugova, I. A.; Yugov, O. A.; Suter, D.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Petrov, V. V.; Dolgikh, Yu. K.; Pawlis, A.; Bayer, M.

2014-08-01

288

Dynamic and Thermal Control of an Electromagnetic Formation Flight Testbed  

E-print Network

the mission. An alternative method for providing this relative position control is to use electromagnetic vehicle position and attitude using only electromagnetic forces and reaction wheels. A thorough. Innovations to the thermal system, used to cool the superconducting wire of the electromagnet, are described

289

Materials for electromagnetic interference shielding  

Microsoft Academic Search

Materials for the electromagnetic interference (EMI) shielding of electronics and radiation sources are reviewed, with emphasis\\u000a on composite materials and resilient EMI gasket materials, which shield mainly by reflection of the radiation at a high frequency.

D. D. L. Chung

2000-01-01

290

Electromagnetics from Simulation to Optimal Design  

E-print Network

1 Electromagnetics from Simulation to Optimal Design Christian Hafner Laboratory for Electromagnetic Fields and Microwave Electronics (IFH) ETH Zurich (Switzerland) Lab: http://www.ifh.ee.ethz.ch COG 23, 2013 #12;2 IFH courses · Advanced engineering electromagnetics (Leuchtmann, start spring 2014

Lang, Annika

291

Geant4 low energy electromagnetic physics  

Microsoft Academic Search

The Geant4 simulation toolkit includes a specialised package, implementing a precise treatment of electromagnetic interactions of particles with matter below 1 keV. The Geant4 low energy electromagnetic package provides a variety of models describing the electromagnetic processes of electrons and positrons, photons, charged hadrons and ions, taking into account detailed features, such as atomic shell effects and charge dependence. Those

S. Chauvie; S. Guatelli; V. Ivanchenko; F. Longo; A. Mantero; B. Mascialino; P. Nieminen; L. Pandola; S. Parlati; L. Peralta; M. G. Pia; M. Piergentili; P. Rodrigues; S. Saliceti; A. Trindade

2004-01-01

292

A technology that squeezes electromagnetic waves  

E-print Network

A technology that squeezes electromagnetic waves into minuscule structures may yield a new and manipulate visible light and other electromagnetic waves--could someday replace electronic circuits in micro match those of the electromagnetic field outside the metal. The result is the generation of surface

Atwater, Harry

293

Virtual Electromagnet  

NSDL National Science Digital Library

This is an interactive online activity, in which learners equip a virtual electromagnet and see how many iron filings it can pick up. Learners change various characteristics of the electromagnet including the number of windings, the gage of the wire, the current type (AC or DC), the material used in the wire, and the voltage on the power supply.

The University of California Regents

2014-01-01

294

Electromagnetic Attraction.  

ERIC Educational Resources Information Center

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)

Milson, James L.

1990-01-01

295

Electromagnetic effects on geodesic acoustic modes  

SciTech Connect

By using the full electromagnetic drift kinetic equations for electrons and ions, the general dispersion relation for geodesic acoustic modes (GAMs) is derived incorporating the electromagnetic effects. It is shown that m?=?1 harmonic of the GAM mode has a finite electromagnetic component. The electromagnetic corrections appear for finite values of the radial wave numbers and modify the GAM frequency. The effects of plasma pressure ?{sub e}, the safety factor q, and the temperature ratio ? on GAM dispersion are analyzed.

Bashir, M. F., E-mail: frazbashir@yahoo.com [Salam Chair in Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Department of Physics, G. C. University Lahore, Katchery Road, Lahore 54000 (Pakistan); Smolyakov, A. I. [University of Saskatchewan, 116 Science Place, Saskatoon S7N 5E2 (Canada); Institute of Tokamak Physics, NRC “Kurchatov Institute,” 123182 Moscow (Russian Federation); Elfimov, A. G. [Institute of Physics, University of São Paulo, São Paulo 05508-090 (Brazil); Melnikov, A. V. [Institute of Tokamak Physics, NRC “Kurchatov Institute,” 123182 Moscow (Russian Federation); National Research Nuclear University MEPhI, 115409, Moscow (Russian Federation); Murtaza, G. [Visiting Professor, Department of Physics, Quaid-e-Azam University, Islamabad (Pakistan)

2014-08-15

296

Stochastic Cooling  

SciTech Connect

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.

Blaskiewicz, M.

2011-01-01

297

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)

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.

Gan, L.; Cravens, T. E.

1992-01-01

298

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)

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 energy degradation of the RC H(+) and O(+) ions maximizes at about 10(exp 11) (eV/(cm(sup 2) (raised dot) s), and typically leads to electron energy deposition rates of about 2(raised dot) 10(exp 10) (eV/(cm(sup 2)(raised dot)s) which are observed during two periods; 32-48 hours, and 76-86 hours after 1 May, 0000 UT. The theoretically derived spatial structure of the thermal electron heating caused by interaction of the ring current with the plasmasphere is strongly supported by concurrent and conjugate plasma measurements from the plasmasphere, ring current, and topside ionosphere [Gurgiolo et al., 2005]. Finally, the wave induced intense electron heating has a structure of the spot-like patches along the most enhanced density gradients in the plasmasphere boundary layer and can be a possible driver to the observed but still not explained small-scale structures of enhanced emissions in the stable auroral red arcs.

Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.; Liemohn, M. W.

2007-01-01

299

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Cooled and uncooled single-channel deformable mirrors for industrial laser systems  

NASA Astrophysics Data System (ADS)

A study was made of bimorph mirrors intended for industrial laser systems. The technical characteristics of cooled single-channel deformable mirrors were investigated in detail. Preliminary tests were made on uncooled bimorph mirrors in industrial laser systems based on a cw CO2 laser with an output power in excess of 2 kW and on a pulsed copper vapour laser with an average power of 35 W.

Vinevich, B. S.; Zharikov, V. M.; Safronov, A. G.

1998-04-01

300

Electromagnetic fasteners  

DOEpatents

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.

Crane, Randolph W. (Idaho Falls, ID); Marts, Donna J. (Idaho Falls, ID)

1994-01-01

301

Aircraft electromagnetic compatibility  

NASA Technical Reports Server (NTRS)

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.

Clarke, Clifton A.; Larsen, William E.

1987-01-01

302

Electromagnetic particle simulation codes  

NASA Technical Reports Server (NTRS)

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.

Pritchett, P. L.

1985-01-01

303

DYNAMICS OF DECAY ELECTRONS AND SYNCHROTRON RADIATION IN A TEV MUON COLLIDER*  

E-print Network

of the vacuum tube and produce an ener- getic electromagnetic cascade in the superconducting coils of the magnetV! Such photons produce energetic showers when they contact the beam tube, contributing about as much heat-mcintyre@physics.tamu.edu LN2-cooled absorber tube #12;absorbers synchrotron radiation vacuum aperture muon beam decay electron

McIntyre, Peter

304

Powerful electromagnetic millimeter-wave oscillations produced by stimulated scattering of microwave radiation by relativistic electron beams  

NASA Astrophysics Data System (ADS)

The results of analytical and experimental studies of stimulated electron scattering in relativistic cm- and mm-wave generators are reported. Carcinotrons and an orotron served as pump generators equipped with corrugated sides to produce a weak harmonic. The resulting beam collided with an electron beam propagating in the opposite direction and produced a scattered beam. The scattered wave frequencies are quantified, noting that the waves in the carcinotrons sometimes satisfied the Bragg condition and run in opposite directions, reflect off one another, oscillate, and can satisfy a synchronism criterion, which induces stimulated scattering. Trials performed with three different generating systems and beam voltages showed that a first order harmonic in a periodic waveguide of the carcinotrons was the same frequency as the scattering radiation. It is concluded that stimulated scattering is a viable technique for obtaining strong single-mode mm-wave signals when mode selection is used.

Denisov, G. G.; Smorgonskii, A. V.; Gubanov, V. P.; Korovin, S. D.; Rostov, V. V.; Ialandin, M. I.

1984-10-01

305

Stochastic cooling at Fermilab  

SciTech Connect

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.

Marriner, J.

1986-08-01

306

Introduction to the special issue on high-power electromagnetics (HPEM) and intentional electromagnetic interference (IEMI)  

Microsoft Academic Search

A new threat to civil society has recently emerged. It is known as intentional electromagnetic interference (IEMI) and covers the threat of intense electromagnetic disturbances that may be applied to the sophisticated electronic systems that are so important to our daily lives. This paper provides a brief background for the threat, defines important terms, describes the different types of electromagnetic

William A. Radasky; Carl E. Baum; Manuem W. Wik

2004-01-01

307

Electromagnetic reactions on light nuclei  

E-print Network

Electromagnetic reactions on light nuclei are fundamental to advance our understanding of nuclear structure and dynamics. The perturbative nature of the electromagnetic probes allows to clearly connect measured cross sections with the calculated structure properties of nuclear targets. We present an overview on recent theoretical ab-initio calculations of electron-scattering and photonuclear reactions involving light nuclei. We encompass both the conventional approach and the novel theoretical framework provided by chiral effective field theories. Because both strong and electromagnetic interactions are involved in the processes under study, comparison with available experimental data provides stringent constraints on both many-body nuclear Hamiltonians and electromagnetic currents. We discuss what we have learned from studies on electromagnetic observables of light nuclei, starting from the deuteron and reaching up to nuclear systems with mass number A=16.

Sonia Bacca; Saori Pastore

2014-07-13

308

3D printed electromagnetic transmission and electronic structures fabricated on a single platform using advanced process integration techniques  

NASA Astrophysics Data System (ADS)

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.

Deffenbaugh, Paul Issac

309

Electromagnetic effects on quasilinear turbulent particle transport  

SciTech Connect

It is well known that a nonadiabatic part of the electron density response is needed for particle transport in tokamaks. Such main reactive effects are electron trapping and electromagnetic induction. Although electron trapping has been studied rather extensively, electromagnetic effects have hardly been studied at all although they are already included in transport codes. Here the electromagnetic effects have been analyzed and parameter studies have been performed, showing that an electromagnetic particle pinch may appear in the flat density regime, just as for the case of electron trapping although the conditions are more restrictive. The particle pinch is particularly sensitive to the direction of propagation of the eigenmode. The electromagnetic particle flux is found to be outward for modes propagating in the ion drift direction and inward for modes propagating in the electron drift direction. A pinch may be obtained rather close to the axis for International Thermonuclear Experimental Reactor simulation data.

Eriksson, Annika; Weiland, Jan [Radio and Space Science, Chalmers University of Technology and EURATOM-VR Association, S-412 96 Goeteborg (Sweden)

2005-09-15

310

Electromagnetic Theory 1 /56 Electromagnetic Theory  

E-print Network

Electromagnetic Theory 1 /56 Electromagnetic Theory Summary: · Maxwell's equations · EM Potentials · Equations of motion of particles in electromagnetic fields · Green's functions · Lienard-Weichert potentials · Spectral distribution of electromagnetic energy from an arbitrarily moving charge #12;Electromagnetic

Bicknell, Geoff

311

Sorption cooling: A valid extension to passive cooling  

NASA Astrophysics Data System (ADS)

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 reduction of the radiator area needed by the sorption cooler. The application field of this type of sorption cooling in space missions is currently being expanded by examining the performance of alternative working fluids, suitable for different cooling temperatures.

Doornink, D. J.; Burger, J. F.; ter Brake, H. J. M.

2008-05-01

312

Sorption cooling: a valid extension to passive cooling  

NASA Astrophysics Data System (ADS)

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 reduction of the radiator area needed by the sorption cooler. By examining the performance of alternative working fluids suitable for different cooling temperatures, the application field of this type of sorption cooling is currently expanded.

Doornink, Jan; Burger, Johannes; ter Brake, Marcel

2007-10-01

313

Magnetism and Electromagnetism  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Magnetism and Electromagnetism, is the fourteenth chapter in Volume I â Direct Current. A few of the topics covered in this chapter include: Permanent magnets; Electromagnetic induction; and Mutual inductance. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-07

314

Electromagnetic Signals from Bacterial DNA  

E-print Network

Chemical reactions can be induced at a distance due to the propagation of electromagnetic signals during intermediate chemical stages. Although is is well known at optical frequencies, e.g. photosynthetic reactions, electromagnetic signals hold true for muck lower frequencies. In E. coli bacteria such electromagnetic signals can be generated by electric transitions between energy levels describing electrons moving around DNA loops. The electromagnetic signals between different bacteria within a community is a "wireless" version of intercellular communication found in bacterial communities connected by "nanowires". The wireless broadcasts can in principle be of both the AM and FM variety due to the magnetic flux periodicity in electron energy spectra in bacterial DNA orbital motions.

A. Widom; J. Swain; Y. N. Srivastava; S. Sivasubramanian

2012-02-09

315

Gravitation and Electromagnetism  

E-print Network

The realms of gravitation, belonging to Classical Physics, and Electromagnetism, belonging to the Theory of the Electron and Quantum Mechanics have remained apart as two separate pillars, inspite of a century of effort by Physicists to reconcile them. In this paper it is argued that if we extend ideas of Classical spacetime to include in addition to non integrability non commutavity also, then such a reconcilation is possible.

B. G. Sidharth

2001-06-16

316

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)

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.

Graham, D. B.; Cairns, Iver H.; Skjaeraasen, O.; Robinson, P. A.

2012-02-01

317

Electromagnetic Effects in SDF Explosions  

Microsoft Academic Search

The notion of high ion and electron concentrations in the detonation of aluminized explosive mixtures has aroused some interest in electro-magnetic effects that the SDF charges might generate when detonated. Motivated by this interest we have started to investigate whether significant electro-magnetic effects show up in our small-scale experiments. However, the design of instrumentation for this purpose is far from

H Reichenbach; P Neuwald; A L Kuhl

2010-01-01

318

State-Selective X-Ray Study of the Radiative Recombination of U92+ Ions with Cooling Electrons  

NASA Astrophysics Data System (ADS)

We report on a state-selective x-ray experiment on recombination of bare U92+ ions with low-energy electrons which was performed, for the first time at non-zero relative electron energies (0-1000 meV), by observing the x-ray photons emitted directly from radiative recombination (RR) and subsequent deexcitation cascades (DC). The results are discussed in terms of the nonrelativistic dipole approximation (NDA). The recombination enhancement effect is observed for K-RR photons at zero relative energy, while for higher energies the discrepancies between data and NDA calculations indicate the importance of the relativistic effects.

Pajek, M.; Stöhlker, Th.; Bana?, D.; Beyer, H. F.; Böhm, S.; Bosch, F.; Brandau, C.; Czarnota, M.; Chatterjee, S.; Dousse, J.-Cl.; Gumberidze, A.; Hagmann, S.; Kozhuharov, C.; Liesen, D.; Müller, A.; Reuschl, R.; Schmidt, E. W.; Sierpowski, D.; Spillmann, U.; Szlachetko, J.; Tashenov, S.; Trotsenko, S.; Verma, P.; Wa?ek, M.; Warczak, A.; Wilk, A.

2006-11-01

319

Electromagnetic Geometry  

E-print Network

We show that Maxwell's electromagnetism can be mapped into the Born-Infeld theory in a curved space-time, which depends only on the electromagnetic field in a specific way. This map is valid for any value of the two lorentz invariants $F$ and $G$ confirming that we have included all possible solutions of Maxwell's equations. Our result seems to show that specifying the dynamics and the space-time structure of a given theory can be viewed merely as a choice of representation to describe the physical system.

M. Novello; F. T. Falciano; E. Goulart

2011-11-08

320

Electromagnet Lesson  

NSDL National Science Digital Library

This hands-on classroom activity will help students understand the connections between magnets and electricity generation. The learning cycle planner includes an exploration phase with a hands-on activity and a suggested video. The concept development phase suggests showing the film "Who Killed the Electric Car?" The main part of this learning unit is the electromagnet lesson, which is a two day small group activity in which students will create an electromagnet. This document may be downloaded in PDF file format; student worksheets are included.

Orzali, Joe

2011-12-08

321

Cavity Cooling with a Hot Cavity Vladan Vuletic  

E-print Network

of the Doppler effect. Conventional Doppler cooling therefore requires a closed two-level system. Alternatively extended electromagnetic modes. Conventional Doppler cooling [5], that makes use of the conservation, realize an atomic laser, or maybe build time machines? Doppler cooling relies on the anisotropic

Vuletic, Vladan

322

Electromagnetic Survey  

USGS Multimedia Gallery

USGS hydrologist conducts a broadband electromagnetic survey in New Orleans, Louisiana. The survey was one of several geophysical methods used during USGS applied research on the utility of the multi-channel analysis of surface waves (MASW) seismic method for non-invasive assessment of earthen levee...

323

Electromagnetic Survey  

USGS Multimedia Gallery

A USGS hydrologist conducts a near-surface electromagnetic induction survey to characterize the shallow earth. The survey was conducted as part of an applied research effort by the USGS Office of Groundwater Branch of Geophysics at Camp Rell, Connecticut, in 2008....

324

ECE 341: Electromagnetic Fields I EM devices and systems  

E-print Network

in material media - Electromagnetic induction - Inductance - Magnetic energy Applications: - ElectronicsECE 341: Electromagnetic Fields I EM devices and systems - Can compute and analyze potentials compositions - Can evaluate capacitance, inductance, resistance, and conductance of EM structures - Understands

Schumacher, Russ

325

Use of oolong tea extract staining of soft-tissue specimens in low-vacuum scanning electron microscope with a cooling stage.  

PubMed

For direct observation of the surface structures of soft-tissue specimens, we examined rat tracheal tissue in a low-vacuum scanning electron microscope (SEM) equipped with a cooling stage. In specimens fixed with glutaraldehyde and osmium tetroxide, back-scattered electron images of the surface structure could not be clearly observed in the low-vacuum SEM because of the disruption of fine structures and a low signal-to-noise (S/N) ratio. Processing of the specimens in 70% ethanol resulted in marked shrinkage, in contrast to results when processing in 30% ethanol. To overcome these problems, the trachea was initially fixed in 2.5% glutaraldehyde (0.1 M phosphate buffer pH 7.4), treated with a mixture of 0.2% oolong tea extract (OTE) and 2.5% glutaraldehyde, and postfixed in 1% osmium tetroxide. The sample was immersed in 30% ethanol and examined in a chilled SEM at -10 degrees C. The luminal coutour of the tracheal epithelial cells was clearly observed because of the decrease in shrinkage. Cilia of ciliated cells and microvilli of nonciliated cells were also clearly observed. These specimens also showed a high S/N ratio, thus allowing the observation of samples without the need for complete dehydration, critical-point drying, or metal coating. This OTE-incorporated conductive staining method is simple and rapid, and should prove to be highly useful for rapid SEM analyses of biological specimens. PMID:11956999

Sasaki, Y; Sato, S; Adachi, A; Dan, Y; Nishimura, M

2001-12-01

326

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Modeling and Computing Example for Effective Electromagnetic Parameters of Multiphase Composite Media  

NASA Astrophysics Data System (ADS)

A method using strong fluctuation theory (SFT) to compute the effective electromagnetic parameters of multiphase composite media, and common materials used to design radar-absorbing materials, is demonstrated. The effective electromagnetic parameters of ultrafine carbonyl-iron (DT-50) and fiber fabric, which are both multiphase composite media and represent coated and structured radar absorbing materials, respectively, are investigated, and the corresponding equations of electromagnetic parameters by using the SFT are attained. Moreover, we design a program to simplify the solutions, and the results are discussed.

Song, Wei-Li; Yuan, Jie; Hou, Zhi-Ling; Cao, Mao-Sheng

2009-05-01

327

Advanced Power Electronics and Electric Motors Annual Report -- 2013  

SciTech Connect

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.

Narumanchi, S.; Bennion, K.; DeVoto, D.; Moreno, G.; Rugh, J.; Waye, S.

2015-01-01

328

Electromagnetic interactions at RHIC and LHC  

E-print Network

At LHC energies the Lorentz factor will be 3400 for the Pb + Pb collisions and the electromagnetic interactions will play important roles. Cross sections for the electromagnetic particle productions are very large and can not be ignored for the lifetimes of the beams and background. In this article, we are going to study some of the electromagnetic processes at RHIC and LHC and show the cross section calculations of the electron-positron pair production with the giant dipole resonance of the ions.

M. C. Guclu

2008-11-15

329

Cool Shelter  

ERIC Educational Resources Information Center

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…

Praeger, Charles E.

2005-01-01

330

Cool Suit  

NASA Technical Reports Server (NTRS)

Acurex developed a heat stress alleviating, liquid cooled helmet liner for military pilots after a series of accidents in Vietnam suggested heat exhaustion as the cause. System pumped a cooled liquid through channels in the helmet liner proved effective in eliminating 40-60% of stored body heat.

1987-01-01

331

MEASURED RESULTS FOR NbN PHONON-COOLED HOT ELECTRON BOLOMETRIC MIXERS AT 0.6-0.75 THz, 1.56 THz, AND 2.5 THz  

E-print Network

MEASURED RESULTS FOR NbN PHONON-COOLED HOT ELECTRON BOLOMETRIC MIXERS AT 0.6-0.75 THz, 1.56 THz, AND 2.5 THz E. Gerecht, C. F. Musante, H. Jian, and K. S. Yngvesson Department of Electrical at frequencies above 1 THz. These HEB mixers have so far demonstrated a DSB noise temperature as low as 500 K

Yngvesson, K. Sigfrid

332

Electromagnetic Reciprocity.  

SciTech Connect

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 geophysical consultant ) and Dr. Chester J. Weiss (recently rejoined with Sandia National Laboratories) for many stimulating (and reciprocal!) discussions regar ding the topic at hand.

Aldridge, David F.

2014-11-01

333

Chapter 18. Electromagnetic and Electronic Systems Electromagnetic and Electronic Systems  

E-print Network

of cycles, since there is no redox chemical reaction), can be charged or discharged in just a few seconds (no redox reaction), and use benign materials (primarily aluminum, carbon, and cellulose). However

334

An optical-optical double resonance probe of the lowest triplet state of jet-cooled thiophosgene: rovibronic structures and electronic relaxation.  

PubMed

The vibrational structure, rotational structure, and electronic relaxation of the "dark" T1 3A2(n,pi*) state of jet-cooled thiophosgene have been investigated by two-color S2<--T1<--S0 optical-optical double resonance (OODR) spectroscopy, which monitors the S2-->S0 fluorescence generated by S2<--T1 excitation. This method is capable of isolating the T1 vibrational structure into a1, b1, and b2 symmetry blocks. The fluorescence-detected vibrational structure of the Tz spin state of T1 shows that the CS stretching frequency as well as the barrier height for pyramidal deformation are significantly greater in the 3A2(n,pi*) state than in the corresponding 1A2(n,pi*) state. The differing vibrational parameters of the T1 thiophosgene relative to the S1 thiophosgene can be attributed to the motions of unpaired electrons that are better correlated when they are in the excited singlet state than when they are in the triplet state of same electron configuration. A set of T1 structural parameters and the information concerning the T1 spin states have been obtained from least-square fittings of the rotationally resolved T1<--S0 excitation spectrum. The nearly degenerate mid R:x and mid R:y spin states are well removed from mid R:z spin component, indicating that T1 thiophosgene is a good example of case (ab) coupling. The decay of the mid R:z spin state of T1 thiophosgene, obtained from time-resolved S2<--T1<--S0 OODR experiment, is characteristic of strong-coupling intermediate-case decay in which an initial rapid decay is followed by recurrences and/or a long-lived quasiexponential decay. PMID:16599668

Fujiwara, Takashige; Lim, Edward C; Judge, Richard H; Moule, David C

2006-03-28

335

Precision Experiments With Stored And Cooled Highly Charged Ions  

NASA Astrophysics Data System (ADS)

Accumulation, storing and cooling techniques play an increasingly important role in many areas of science. These procedures can be applied in Penning traps and storage rings to ions. In this way, quantum electrodynamics can be tested in extreme electromagnetic fields by measuring hyperfine structure splittings. Lamb shifts, or g-factors in hydrogen-like heavy systems such as U91+ or Pb81+. In addition, fundamental constants or nuclear properties like the atomic mass can be determined. In the case of a radioactive ion, the fate of an individual ion, undergoing a nuclear decay, can be studied in detail by observing the disappearance of the signal of the mother and the appearance of that of the daughter isotope. Presently, the Highly-charged Ion TRAP (HITRAP) facility is being built up at GSI. Stable or radioactive highly charged ions are produced by colliding relativistic ions with a target. After electron cooling and deceleration in the storage ring ESR at GSI, these ions are ejected, decelerated further, and injected into a Penning trap where cooling to 4 K takes place. From there, the cooled highly charged ions such as hydrogen-like uranium are transferred at low energy to different experimental set-ups which are being built up by the international HITRAP Collaboration.

Kluge, H.-Jürgen

2006-11-01

336

Suppressing electromagnetic interference in direct current converters  

Microsoft Academic Search

Since James Clerk Maxwell established the electromagnetic field theory in 1865, multifarious electrical and electronic products have been invented, designed, produced, and widely deployed, such as wireless communication devices, electrical machines and motors. This has profoundly changed our world and our lives. Now we cannot live without electrical products anymore and, thus, we are surrounded with electromagnetic fields generated. On

Hong Li; Zhong Li; Bo Zhang; Wallace Tang; Wolfgang Halang

2009-01-01

337

Cooled railplug  

DOEpatents

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.

Weldon, William F. (Austin, TX)

1996-01-01

338

Physics-of-failure analysis of cooling fans  

Microsoft Academic Search

The use of cooling fans is a low-cost solution for thermal management in electronic products. Cooling fans are used to create designed airflow to cool down the host system. Since many failures in the field can be traced back to thermally­ related issues in electronic products, the reliability of cooling fans is a critical part of the overall reliability of

Xiaohang Jin; Michael H. Azarian; Chunpiu Lau; LL Cheng; Michael Pecht

2011-01-01

339

Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics.  

PubMed

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 distortion parameter (TDP). Thus, this material presents a viable and efficient alternative to existing materials for thermal management in electronics. PMID:24441433

Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

2014-03-01

340

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)

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 plasmaspheric electrons are considered; (i) the heat fluxes caused by the EMIC wave energy absorption due to Landau resonance, and (ii) the heat fluxes due to Coulomb energy degradation of the RC o(+) ions. The heat fluxes caused by the EMIC wave energy absorption due to Landau resonance are observed in the postnoon-premidnight MLT sector, and maximize at the magnitude of 10l1 (eV/(cm(sup 2)(raised dot) s) at L=3.25, MLT=22 at 3400 UT after 1 May, 0000 UT. The greatest Coulomb energy deposition rates are about 2 (raised dot) 10(sup 10)(eV/(cm(sup 2)(raised dot) s) and observed during two periods; 32-48 hours, and 76-86 hours after 1 May, 0000 UT. The theoretically derived spatial structure of the thermal electron heating caused by interaction of the RC with plasmasphere is strongly supported by concurrent and conjugate plasma measurements from the plasmasphere, the RC, and the topside ionosphere [Gurgiolo et al., 20051.

Khazanov, G. V.; Gamayunov, K. V.; Gallagher, D. L.

2006-01-01

341

Contribution of the ? electron to the N-H···O=C hydrogen bond: IR spectroscopic studies of the jet-cooled pyrrole-acetone binary clusters.  

PubMed

To investigate the ? bonding electron contribution to N-H···O=C hydrogen-bond (H-bond) formation, we applied IR cavity ringdown spectroscopy to jet-cooled pyrrole-acetone (Py-Ac) binary clusters. The observed NH stretching vibrations were analyzed by density functional theory (DFT), in which the energetically optimized structures, harmonic frequencies, and interaction energies were calculated for various sizes of binary clusters. We observed three NH stretching vibrations, ascribed to binary clusters at 3406, 3388, and 3335 cm(-1). These were assigned to H-bonded NH stretches of the Py(2)-Ac(1), Py(1)-Ac(1), and Py(1)-Ac(2) clusters, respectively. The Py(1)-Ac(1) cluster has a single N-H···O=C H-bonded structure with C(s) symmetry, while the Py(1)-Ac(2) cluster has a cyclic structure formed by a single N-H···O=C H-bond, dipole-dipole interactions, and weak CH H-bonds. A natural bond orbital (NBO) analysis was performed to reveal the H-bond strength in Py-Ac binary clusters. For the Py(1)-Ac(2) cluster, we found that the donor-acceptor interactions are not only the n ??* type (O atom lone pair to the NH anti-bonding orbitals), but also the ???* type (the CO ? bonding to the NH anti-bonding orbitals). By analyzing the relationship between the frequency shift and the stabilization energy in donor-acceptor interactions, we concluded that larger red-shift of the NH stretching vibration in the Py(1)-Ac(2) can be explained by not only the lone pair and the ? electron contributions to the N-H···O=C H-bond, but also the dipole-interaction between Py and non-H-bonded Ac. We also discussed the structures of Py(2)-Ac(1) clusters. PMID:22899308

Matsumoto, Yoshiteru; Iwamoto, Jun-ichi; Honma, Kenji

2012-10-01

342

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)

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.

Wang, Jung-Chang

2014-04-01

343

Transient electromagnetic interference in substations  

Microsoft Academic Search

Electromagnetic interference levels on sensitive electronic equipment are quantified experimentally and theoretically in air and gas insulated substations of different voltages. Measurement techniques for recording interference voltages and currents and electric and magnetic fields are reviewed and actual interference data are summarized. Conducted and radiated interference coupling mechanisms and levels in substation control wiring are described using both measurement results

C. M. Wiggins; D. E. Thomas; F. S. Nickel; T. M. Salas; S. E. Wright

1994-01-01

344

Creating an Electromagnet  

NSDL National Science Digital Library

Student teams investigate the properties of electromagnets. They create their own small electromagnet and experiment with ways to change its strength to pick up more paper clips. Students learn about ways that engineers use electromagnets in everyday applications.

Integrated Teaching And Learning Program

345

An experimental and ab initio study of the electronic spectrum of the jet-cooled F{sub 2}BO free radical  

SciTech Connect

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.

Grimminger, Robert; Clouthier, Dennis J., E-mail: dclaser@uky.edu [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Sheridan, Phillip M. [Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208 (United States)] [Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208 (United States)

2014-04-28

346

Advance in MEIC cooling studies  

SciTech Connect

Cooling of ion beams is essential for achieving a high luminosity for MEIC at Jefferson Lab. In this paper, we present the design concept of the electron cooling system for MEIC. In the design, two facilities are required for supporting a multi-staged cooling scheme; one is a 2 MeV DC cooler in the ion pre-booster; the other is a high electron energy (up to 55 MeV) ERL-circulator cooler in the collider ring. The simulation studies of beam dynamics in an ERL-circulator cooler are summarized and followed by a report on technology development for this cooler. We also discuss two proposed experiments for demonstrating high energy cooling with a bunched electron beam and the ERL-circulator cooler.

Zhang, Yuhong [JLAB, Newport News, VA (United States); Derbenev, Ya. [JLAB, Newport News, VA (United States); Douglas, D. [JLAB, Newport News, VA (United States); Hutton, A. [JLAB, Newport News, VA (United States); Kimber, A. [JLAB, Newport News, VA (United States); Li, R. [JLAB, Newport News, VA (United States); Nissen, E. [JLAB, Newport News, VA (United States); Tennant, [JLAB, Newport News, VA (United States); Zhang, H. [JLAB, Newport News, VA (United States)

2013-06-01

347

Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics  

NASA Astrophysics Data System (ADS)

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 distortion parameter (TDP). Thus, this material presents a viable and efficient alternative to existing materials for thermal management in electronics.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 temper

Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji

2014-02-01

348

Electromagnetic analysis of the experimental setup used to investigate the ratchet effect in two-dimensional electron system under microwave radiation  

Microsoft Academic Search

This paper addresses simulation and analysis of the experimental setup for investigation of ratchet effect on semiconductor heterojunctions with periodic array of artificial semi-disc shaped antidots. For the first time, the electromagnetic incident power across the sample is computed here and the uniformity of the incident electric field linear polarization is characterized. These two preliminary full-wave simulation results are very

A. Takacs; D. Medhat; H. Aubert; J. C. Portal

2009-01-01

349

Cooling Off  

NSDL National Science Digital Library

In this activity, learners are introduced to challenges of maintaining temperatures while living in space. Thinking and acting like scientists and engineers, learners experiment to learn how to measure the specific heat capacity (or simply, specific heat) of water and then design an improved cooling system like those used in spacesuits. This lesson is developed using a 5E model of learning. In the ENGAGE section of the lesson, learners look at NASA technology and its relationship to improvements in athletic clothing and equipment. They learn about technology in spacesuit design and the use of this technology in everyday life. Working in teams, students conduct experiments relating to specific heat capacity on a cooling system they design in the EXPLORE and EXPLAIN sections. They are challenged to improve the cooling system in the EXTEND section of this lesson. Learners assess their understanding and abilities throughout the lesson and revisit the Essential Questions during the EVALUATE section.

NASA

2014-06-27

350

Cooled railplug  

DOEpatents

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.

Weldon, W.F.

1996-05-07

351

k-space drift due to the density variation as a cause of electromagnetic emission generation of type III solar radio bursts by a non-gyrotropic electron beam  

NASA Astrophysics Data System (ADS)

It is widely accepted that there is a correlation between super-thermal electron beams and type III solar radio bursts. Whilst the correlation is an established fact, the actual mechanism that generates the type III burst emission is not yet fully determined. The main source of the uncertainty is current inability to send in-situ probes at distances 0.15 - 1.5Rsun from the solar surface (photosphere). The most widely accepted mechanism, that historically appeared first is the plasma emission. In plasma emission mechanism quasilinear theory, kinetic Fokker-Planck type equation for describing the dynamics of an electron beam is used, in conjunction with the spectral energy density evolutionary equations for Langmuir and ion-sound waves. Further, non-linear wave-wave interactions between Langmuir, ion-acoustic and EM waves produce emission at electron plasma frequency, ?pe or the second harmonic, 2?pe. A variant of the plasma emission mechanism is the stochastic growth theory, where density irregularities produce a random growth, in such a way that Langmuir waves are generated stochastically and quasilinear interactions within the Langmuir clumps cause the beam to fluctuate about marginal stability. The latter models have been used for producing the solar type III burst observable parameters. Other possible mechanisms include: linear mode conversion, antenna radiation and non-gyrotropic electron beam emission [1]. Recent works [2,3] elucidated further the non-gyrotropic electron beam emission, first proposed in Ref.[1]. In particular, the effect of electron beam pitch angle and density gradient on solar type III radio bursts was studied [2] and the role of electron cyclotron maser (ECM) emission with a possible mode coupling to the z-mode was explored [3]. In this contribution and paper [4], using large-scale Particle-In-Cell simulations, we explore the non-gyrotropic electron beam emission mechanism by studying the effects of electron beam kinetics and k-space drift, in long term evolution of electromagnetic emission generation of type III solar radio bursts. The following improvements and progress in understanding of the radio emission mechanism are made: (i) Improved numerical simulations with larger spatial domain and longer end-simulation times; (ii) The electron beam injection on a density plateau followed by a decreasing density gradient that mimics the Sun-earth system; (iii) Consideration of a ring and shifted ring electron initial velocity distribution functions; (iv) The role of the k-space drift in the radio emission; (v) Estimation of the ECM growth rate and its role in the emission generation. It is worthwhile to note that Ref.[3] proposed mode coupling on the density gradient as a source of radio emission as opposed to the k-space drift advocated in the present work. The situation is analogous to the auroral waves emitted near the plasma frequency in Earth auroral ionosphere [A. Layden, I. H. Cairns, P. A. Robinson, and J. LaBelle, J. Geophys. Res. 116, A12328 (2011)]. [1] D. Tsiklauri, "An alternative to the plasma emission model: Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts", Physics of Plasmas 18, 052903 (2011) [2] R. Pechhacker, D. Tsiklauri, "The effect of electron beam pitch angle and density gradient on solar type III radio bursts", Phys. Plasmas 19, 112903 (2012) [3] R. Pechhacker, D. Tsiklauri, "Electron cyclotron maser emission mode coupling to the z-mode on a longitudinal density gradient in the context of solar type III bursts", Phys. Plasmas 19, 110702 (2012) [4] H. Schmitz, D. Tsiklauri, "k-space drift due to the density variation as a cause of electromagnetic emission generation of type III solar radio bursts by a non-gyrotropic electron beam", Phys. Plasmas, in preparation, (2013)

Tsiklauri, David; Schmitz, Holger

2013-04-01

352

Electromagnetic topology: Characterization of internal electromagnetic coupling  

NASA Technical Reports Server (NTRS)

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.

Parmantier, J. P.; Aparicio, J. P.; Faure, F.

1991-01-01

353

Electromagnetic radiation from beam-plasma instabilities  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

354

Cooling vest  

NASA Technical Reports Server (NTRS)

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.

Kosmo, J.; Kane, J.; Coverdale, J.

1977-01-01

355

Narrow field electromagnetic sensor system and method  

DOEpatents

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.

McEwan, Thomas E. (Livermore, CA)

1996-01-01

356

Electromagnetic Field Theory  

E-print Network

Electromagnetic Field Theory BO THID� UPSILON BOOKS #12;#12;ELECTROMAGNETIC FIELD THEORY #12;#12;Electromagnetic Field Theory BO THID� Swedish Institute of Space Physics and Department of Astronomy and Space, Sweden UPSILON BOOKS · COMMUNA AB · UPPSALA · SWEDEN #12;Also available ELECTROMAGNETIC FIELD THEORY

Hart, Gus

357

Direct Liquid Cooling of High Flux Micro and Nano Electronic Components Boiling, evaporation, jet, and spray cooling, by suitable liquids such as fluorocarbons, might serve to control chip hot-spots and overheating  

Microsoft Academic Search

The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1k W\\/cm 2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical

Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

358

Cool Sportswear  

NASA Technical Reports Server (NTRS)

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.

1982-01-01

359

Cool Science  

NSDL National Science Digital Library

Science is quite cool, but you don't need to tell this to the dedicated team at the Howard Hughes Medical Institute. Their website, Cool Science, entertains questions of all kinds, encourages young scientists to "get their hands dirty", and also provides educators with a range of resources, including interactive media features, lesson plans, and lab exercises. These materials are contained with six primary sections: "For Educators", "Biointeractive", "For Curious Kids", and "Ask A Scientist". Educators of all stripes can use the "For Educators" area to focus in on resources organized by type, topic, grade level, and also to sign up for the resources RSS feed. Moving on, the "Biointeractive" area features archived video lectures, virtual labs, and another series of animations on stem cells, cancer, and immunology. There's a great deal to explore here, and it's a site that anyone with an interest in science will want to share with others.

360

7. Electromagnetic relations 1 7. ELECTROMAGNETIC RELATIONS  

E-print Network

7. Electromagnetic relations 1 7. ELECTROMAGNETIC RELATIONS Revised September 2005 by H.G. Spieler = 10-7 N A-2 ; c = 1 0 0 = 2.997 924 58 Ã? 108 m s-1 #12;2 7. Electromagnetic relations 7.1. Impedances of self-inductance L: Z = jL . Impedance of capacitance C: Z = 1/jC . Impedance of free space: Z = 0/ 0

361

CONTINUUM ELECTROMAGNETIC RADIATION FROM SOLAR FLARES  

Microsoft Academic Search

Continuum electromagnetic radiation from solar flares is discussed in ; terms of the energy loss processes of electrons in the solar atmosphere. It is ; shown that it is possible to attribute the continuum radiation both at radio ; frequencies and at visible frequencies to synchrotron radiation by exponential ; rigidity distributions of electrons. (auth);

W. A. Stein; E. P. Ney

1963-01-01

362

Electromagnetic compatibility design guideline for STADAN  

NASA Technical Reports Server (NTRS)

Procedures for achieving electromagnetic compatibility in electronic and electrical equipment for aerospace ground stations are investigated. The application of shielding theory to good design is treated and standards of good practice are outlined for bonding, grounding, wiring, and cabling. Some aspects of filter design are explained, and suggestions are given for the application of filters to electronic and electrical equipment.

Cowdell, R. B.; Hill, J. S.; Senn, J. C.; Shifman, J. C.; Skaggs, J. W.

1971-01-01

363

Ultrafast semiconductor spectroscopy using terahertz electromagnetic pulses  

Microsoft Academic Search

Terahertz electromagnetic pulses can serve as a new and unique tool for various types of spectroscopy. We first characterized the temporal and spatial properties of THz pulses generated from a large-aperture photoconductive antena, and then used them for the study of the ultrafast dynamics of electrons in semiconductros. We studied the dynamics of electrons generated by femtosecond optical pulses with

Toshiaki Hattori; Satoshi Arai; Keisuke Ohta; Aya Mochiduki; Shin-ichi Ookuma; Keiji Tukamoto; Rakchanok Rungsawang

2005-01-01

364

Electromagnetic Spectrum from QGP Fluid  

Microsoft Academic Search

We calculate thermal photon and electron pairdistribution from hot QCD matter produced in high energy heavy-ion collisions, based on a hydrodynamical model which is so tuned as to reproduce the recent experimental data at CERN SPS, and compare these electromagnetic spectra with experimental data given by CERN WA80 and CERES. We investigate mainly the effects of the off-shell properties of

Tetsufumi Hirano; Shin Muroya; Mikio Namiki

1997-01-01

365

Development of the strong electromagnet wiggler  

SciTech Connect

The Strong Electromagnet (SEM) wiggler is a permanent magnet-assisted electromagnet under development at the Lawrence Livermore National Laboratory (LLNL) as part of the Induction Linac Free-Electron-Laser (IFEL) program. This concept uses permanent magnets within the wiggler to provide a reverse bias flux in the iron and thus delay the onset of magnetic saturation. The electromagnet coils determine th4e wiggler field and operate at low current densities by virtue of their placement away from the midplane. The authors describe the design approach used and test data from a 7-period wiggler prototype that includes curved pole tips to provide wiggler-plane focusing.

Burns, M.J.; Deis, G.A.; Holmes, R.H.; Van Maren, R.D.; Halbach, K.

1988-03-01

366

Renovated cooling at PIMU  

NASA Astrophysics Data System (ADS)

An electronic temperature control system for the cool water circuit at the PIMU section is described. The system consists of a temperature reader, control, offset and switch print, a programmable logic circuit (plc) and a motor speed control unit for the ventilators. From 21 to 6 C, with every 1.4 C temperature increase an extra cooling unit is switched on up to 30 C; every unit is switched off 1.4 C lower than its switching on temperature. Switching on a unit, an air value is opened and a ventilator starts on 10% of its maximum power and is regulated with the temperature increase within the 1.4 C step.

Degroen, P.

1985-04-01

367

Quantum states and linear response in dc and electromagnetic fields for the charge current and spin polarization of electrons at the Bi/Si interface with the giant spin-orbit coupling  

SciTech Connect

An expansion of the nearly free-electron model constructed by Frantzeskakis, Pons, and Grioni [1] describing quantum states at the Bi/Si(111) interface with the giant spin-orbit coupling is developed and applied for the band structure and spin polarization calculation, as well as for the linear response analysis of the charge current and induced spin caused by a dc field and by electromagnetic radiation. It is found that the large spin-orbit coupling in this system may allow resolving the spin-dependent properties even at room temperature and at a realistic collision rate. The geometry of the atomic lattice combined with spin-orbit coupling leads to an anisotropic response for both the current and spin components related to the orientation of the external field. The in-plane dc electric field produces only the in-plane components of spin in the sample, while both the in-plane and out-of-plane spin components can be excited by normally propagating electromagnetic wave with different polarizations.

Khomitsky, D. V., E-mail: khomitsky@phys.unn.ru [Lobachevskii State University of Nizhni Novgorod (Russian Federation)

2012-05-15

368

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 Central

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). PMID:24089662

Gryz, Krzysztof

2013-01-01

369

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

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). PMID:24089662

Karpowicz, Jolanta; Gryz, Krzysztof

2013-01-01

370

Electromagnetic Calorimeter for HADES  

E-print Network

We propose to build the Electromagnetic calorimeter for the HADES di-lepton spectrometer. It will enable to measure the data on neutral meson production from nucleus-nucleus collisions, which are essential for interpretation of dilepton data, but are unknown in the energy range of planned experiments (2-10 GeV per nucleon). The calorimeter will improve the electron-hadron separation, and will be used for detection of photons from strange resonances in elementary and HI reactions. Detailed description of the detector layout, the support structure, the electronic readout and its performance studied via Monte Carlo simulations and series of dedicated test experiments is presented. The device will cover the total area of about 8 m^2 at polar angles between 12 and 45 degrees with almost full azimuthal coverage. The photon and electron energy resolution achieved in test experiments amounts to 5-6%/sqrt(E[GeV]) which is sufficient for the eta meson reconstruction with S/B ratio of 0.4% in Ni+Ni collisions at 8 AGeV. A purity of the identified leptons after the hadron rejection, resulting from simulations based on the test measurements, is better than 80% at momenta above 500 MeV/c, where time-of-flight cannot be used.

W. Czyzycki; E. Epple; L. Fabbietti; M. Golubeva; F. Guber; A. Ivashkin; M. Kajetanowicz; A. Krasa; F. Krizek; A. Kugler; K. Lapidus; E. Lisowski; J. Pietraszko; A. Reshetin; P. Salabura; Y. Sobolev; J. Stanislav; P. Tlusty; T. Torrieri; M. Traxler

2011-09-26

371

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...

372

Electromagnetic properties of neutrinos  

E-print Network

A short review on electromagnetic properties of neutrinos is presented. In spite of many efforts in the theoretical and experimental studies of neutrino electromagnetic properties, they still remain one of the main puzzles related to neutrinos.

Carlo Giunti; Alexander Studenikin

2010-06-08

373

Electromagnetic effects on transportation systems  

SciTech Connect

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.

Morris, M.E.; Dinallo, M.A.

1996-05-01

374

Electromagnetic Measurements at RHIC  

E-print Network

Electromagnetic Measurements at RHIC Hideki Hamagaki Center for Nuclear Study University of Tokyo #12;2/10/2005 "Electromagnetic measurements at RHIC"@ICPAQGP 05 Hideki Hamagaki 2 Prologue · EM probe and where they are produced; #12;2/10/2005 "Electromagnetic measurements at RHIC"@ICPAQGP 05 Hideki Hamagaki

Hamagaki, Hideki

375

Electromagnetic Measurements at RHIC  

E-print Network

Electromagnetic Measurements at RHIC Hideki Hamagaki Center for Nuclear Study Graduate School of Science the University of Tokyo #12;2006/06/29 "Electromagnetic measurements at RHIC"@ATHIC 2006 Hideki;2006/06/29 "Electromagnetic measurements at RHIC"@ATHIC 2006 Hideki Hamagaki 3 Prologue ­ scope of EM measurements · EM

Hamagaki, Hideki

376

The CPLEAR electromagnetic calorimeter  

NASA Astrophysics Data System (ADS)

A large-acceptance lead/gas sampling electromagnetic calorimeter (ECAL) was constructed for the CPLEAR experiment to detect photons from decays of ? 0s with momentum p?0 ? 800 MeV/ c. The main purpose of the ECAL is to determine the decay vertex of neutral-kaon decays K 0 ? ? 0? 0 ? 4? and K 0 ? ? 0? 0? 0 ? 6?. This requires a position-sensitive photon detector with high spatial granularity in r-, ?-, and z-coordinates. The ECAL - a barrel without end-caps located inside a magnetic field of 0.44 T - consists of 18 identical concentric layers. Each layer of {1}/{3} radiation length ( X0) contains a converter plate followed by small cross-section high-gain tubes of 2640 mm active length which are sandwiched by passive pick-up strip plates. The ECAL, with a total of 6 X0 has an energy resolution of {?(E)}/{E} ? {13%}/{(E( GeV) }and a position resolution of 4.5 mm for the shower foot. The shower topology allows separation of electrons from pions. The design, construction, read-out electronics, and performance of the detector are described.

Adler, R.; Backenstoss, G.; Bal, F.; Behnke, O.; Bloch, P.; Damianoglou, D.; Dechelette, P.; Dröge, M.; Eckart, B.; Felder, C.; Fetscher, W.; Fidecaro, M.; Garreta, D.; Gerber, H.-J.; Gumplinger, P.; Guyon, D.; Johner, H. U.; Lofstedt, B.; Kern, J.; Kokkas, P.; Krause, H.; Mall, U.; Marin, C.; Nanni, F.; Pagels, B.; Pavlopoulos, P.; Petit, P.; Polivka, G.; Rheme, Ch.; Ruf, T.; Santoni, C.; Schaller, L. A.; Schopper, A.; Tauscher, L.; Tschopp, H.; Weber, P.; Wendler, H.; Witzig, C.; Wolter, M.; Cplear Collaboration

1997-02-01

377

Health Monitoring of Cooling Fans Based on Mahalanobis Distance With mRMR Feature Selection  

Microsoft Academic Search

Cooling fans are widely used for thermal management in electronic products. The failure of cooling fans may cause electronic products to overheat, which can shorten the product's life, cause electronic components to burn, and even result in catastrophic consequences. Thus, there is a growing interest in health monitoring and anomaly detection for cooling fans in electronic products. A novel method

Xiaohang Jin; Eden W. M. Ma; L. L. Cheng; Michael Pecht

2012-01-01

378

Phenomenology of the Deuteron Electromagnetic Form Factors  

E-print Network

A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm^-1. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.

TheJLAB t20 collaboration; D. Abbott

2000-02-04

379

Semiconductor cooling by thin-film thermocouples  

NASA Technical Reports Server (NTRS)

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.

Tick, P. A.; Vilcans, J.

1970-01-01

380

Cooling tower  

SciTech Connect

This patent describes a cooling tower comprising: an outer structure composed of a side wall and a top cover; the top cover having an opening on its center with a deflection device for reducing re-circulation of air within the housing; a motor which is fixed in a motor seat and whose shaft forms a spindle which rotates a rotatable cylinder; a rotatable cylinder having sides which have a plurality of small apertures, a centrifugal fan being an integral part of the rotating cylinder, the bottom portion of the cylinder engaging the shaft of the motor, the centrifugal fan comprising: a first flange on the top portion, a second flange on the portion with apertures, a plurality of blades which are equally spaced and fixed between the first and second flanges; a screen positioned concentrically around the rotatable cylinder and secured onto the inside of the top cover of the outer structure, the screen comprising a net and a frame, the frame further comprising a flange and skirt, the frame being secured onto the inside of the top cover of the outer structure with the flange, the skirt extending upwards and inwards through the bottom portion of the rotatable cylinder, the net adherent to the frame.

Liu, W.H.

1987-08-18

381

Metallic Glass Cooling  

NASA Technical Reports Server (NTRS)

A sample of advanced metallic glass alloy cools down during an experiment with the TEMPUS furnace on STS-94, July 7, 1997, MET:5/23:35 (approximate). The sequence shows the sample glowing, then fading to black as scientists began the process of preserving the liquid state, but lowering the temperature below the normal solidification temperature of the alloy. This process is known as undercooling. (10 second clip covering approximately 50 seconds.) TEMPUS (stands for Tiegelfreies Elektromagnetisches Prozessiere unter Schwerelosigkeit (containerless electromagnetic processing under weightlessness). It was developed by the German Space Agency (DARA) for flight aboard Spacelab. The DARA project scientist was Igon Egry. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). DARA and NASA are exploring the possibility of flying an advanced version of TEMPUS on the International Space Station. (354KB JPEG, 2700 x 2038 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300189.html.

2003-01-01

382

A study on semisolid processing of A356 aluminum alloy through vacuum-assisted electromagnetic stirring  

Microsoft Academic Search

In this study, a vacuum-assisted electromagnetic stirring system was designed and manufactured in order to minimize the defects\\u000a such as porosities in the semisolid processing A356 aluminum alloy by electromagnetic stirring (EMS). A sleeve cooling system\\u000a was manufactured and two different cooling media (air and water) were tested for the stirred and unstirred slurries. For the\\u000a stirred slurry, the obtained

Il-Gab Chung; Amir Bolouri; Chung-gil Kang

383

Spin bath maser in a cryogenically cooled sapphire whispering gallery mode resonator  

E-print Network

We report the observation of a mechanism of maser generation in an ensemble of inter-coupled, inhomogeneously broadened two-level systems, enhanced by high quality factor electromagnetic cavity modes. In this previously unobserved form of population inversion, an inseparable quantum system leads to cavity-enhanced stimulated emission arising from interactions within an ensemble of two-level systems, as opposed to a traditional ensemble of noninteracting identical three level systems. The effect is observed in a cryogenically cooled whispering gallery mode sapphire resonator containing dilute Fe$^{3+}$ impurity ions. These ions exhibit strong spin-lattice interaction, leading to both electron spin resonance broadening and phonon mediated spin-spin coupling. The maser effect is due to a $\\left|1/2\\right\\rangle \\rightarrow \\left|3/2\\right\\rangle$ energy transition in electron spin angular momentum observed at zero external magnetic field. Both continuous and oscillating regimes are observed with corresponding th...

Bourhill, J; Goryachev, M; Creedon, D L; Farr, W G; Tobar, M E

2013-01-01

384

Simultaneously Forbidden Resonances and Ion Cooling  

NASA Astrophysics Data System (ADS)

Recently, an ion cooling scheme was proposed (Morigi, J. Eschnerand C. Keitel, Phys. Rev. Lett. 85), 4458 (2000) and experimentally demonstrated (C.F. Roos, et al., Phys. Rev. Lett. 85), 5547 (2000). This technique is based on the concept of simultaneously forbidden resonances (V.N. Smelyanskiy, R.S. Conti, and G.W. Ford, Phys. Rev. A 55), 2186 (1997) combined with electromagnetically induced transparency. Possible improvements and extensions will be discussed.

Conti, R. S.

2001-05-01

385

Film cooling performance of liner cooling devices  

Microsoft Academic Search

Data on the film cooling performance of several liner cooling devices are obtained over the range of velocity and density ratios relevant to gas turbines. Among the devices with tangential injection, the wiggle strip device and the machined ring with skirt construction provide the most effective film cooling. The addition of a skirt to the wiggle strip may improve its

B. R. Pai; R. Lakshminarayanan

1981-01-01

386

Electromagnetically Clean Solar Arrays  

NASA Technical Reports Server (NTRS)

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 wiring on the back of the panel. Each step increases the potential for occurrence of latent defects, loss of process control, and attrition of components. An EMCSA panel includes an integral cover made from a transparent material. The silicone cover supplants the individual cover glasses on the cells and serves as an additional unitary structural support that offers the advantage, relative to glass, of the robust, forgiving nature of the silcone material. The cover contains pockets that hold the solar cells in place during the lamination process. The cover is coated with indium tin oxide to make its surface electrically conductive, so that it serves as a contiguous, electrically grounded shield over the entire panel surface. The cells are mounted in proximity to metallic printed wiring. The painted-wiring layer comprises metal-film traces on a sheet of Kapton (or equivalent) polyimide. The traces include contact pads on one side of the sheet for interconnecting the cells. Return leads are on the opposite side of the sheet, positioned to form the return currents substantially as mirror images of, and in proximity to, the cell sheet currents, thereby minimizing magnetic moments. The printed-wiring arrangement mimics the back-wiring arrangement of conventional solar arrays, but the current-loop areas and the resulting magnetic moments are much smaller because the return-current paths are much closer to the solar-cell sheet currents. The contact pads are prepared with solder fo electrical and mechanical bonding to the cells. The pocketed cover/shield, the solar cells, the printed-wiring layer, an electrical bonding agent, a mechanical-bonding agent, a composite structural front-side face sheet, an aluminum honeycomb core, and a composite back-side face sheet are all assembled, then contact pads are soldered to the cells and the agents are cured in a single lamination process.

Stem, Theodore G.; Kenniston, Anthony E.

2008-01-01

387

Detailed observations of the source of terrestrial narrowband electromagnetic radiation  

Microsoft Academic Search

We present detailed observations of a region near the terrestrial plasmapause where narrowband electromagnetic radiation (previously called escaping nonthermal continuum radiation) is being generated. These observations show a direct correspondence between the narrowband radio emissions and electron cyclotron harmonic waves near the upper hybrid resonance frequency. In addition, electromagnetic radiation propagating in the Z-mode is observed in the source region

W. S. Kurth

1982-01-01

388

Amplification of electromagnetic waves in dusty nonstationary plasmas  

NASA Astrophysics Data System (ADS)

The propagation of electromagnetic radiation in multicomponent unmagnetized plasmas with dust particulates is investigated. It is demonstrated that the effect of capture of electrons by the dust particles can give rise to an amplification of the electromagnetic waves. The results could be important for the interpretation of high-frequency waves in space and astrophysical dusty plasmas.

Vladimirov, Sergey V.

1994-02-01

389

Amplification of electromagnetic waves in dusty nonstationary plasmas  

Microsoft Academic Search

The propagation of electromagnetic radiation in multicomponent unmagnetized plasmas with dust particulates is investigated. It is demonstrated that the effect of capture of electrons by the dust particles can give rise to an amplification of the electromagnetic waves. The results could be important for the interpretation of high-frequency waves in space and astrophysical dusty plasmas.

Sergey V. Vladimirov

1994-01-01

390

Narrowband Electromagnetic Emissions at Saturn Revisited: Cassini Observations  

Microsoft Academic Search

Voyager observations revealed the existence of a complex set of narrowband electromagnetic emissions at Saturn in the frequency range of 3 to 30 kHz. These were found to be generated by mode conversion from electrostatic upper hybrid waves into ordinary mode electromagnetic waves which could freely propagate from the source. The frequency spacings of the narrowband emissions near the electron

W. S. Kurth; D. A. Gurnett; B. Cecconi; G. B. Hospodarsky; W. M. Farrell; M. D. Desch; M. L. Kaiser; P. Canu

2005-01-01

391

Software Detection of Hardware Plateform Failures due to Electromagnetic Fields  

E-print Network

Software Detection of Hardware Plateform Failures due to Electromagnetic Fields MOTET Gilles1 of embedded electronic systems susceptibility to electromagnetic fields is often obtained by hardware devices the system safety as this technology is sensitive to the stresses of the environment and, in particular

Paris-Sud XI, Université de

392

Challenges of the naval electromagnetic environment for the EMC engineer  

Microsoft Academic Search

A naval ship has a dense electromagnetic environment onboard due to the presence of myriad electrical, electronic and electromechanical systems within a limited amount of space. These systems are expected to perform to their design potential based on which the ship's roles and missions are decided. However, mutual electromagnetic interference (EMI) between these systems degrades equipment performance, sometimes to such

K. R. Raghu

2003-01-01

393

Electromagnetic structure of pion  

SciTech Connect

In this work, we analyze the electromagnetic structure of the pion, an elementary particle composed by a quark-antiquark bound state, by considering the calculation of its electromagnetic radius and its electromagnetic form factor in low and intermediate energy range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion, in the formalism of the light-front field theory. In particular, it is considered a nonsymmetrical vertex for such a model, in which we have calculated the electromagnetic form factor of the pion in an optimized way, by varying its regulator mass, so that we can obtain the best value for the pion electromagnetic radius when compared with the experimental one. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

Mello, Clayton S.; Cruz Filho, Jose P.; Da Silva, Edson O.; El-Bennich, Bruno; De Melo, J. P.; Filho, Victo S. [Laboratorio de Fisica Teorica e Computacional (LFTC), Universidade Cruzeiro do Sul, 01506-000, Sao Paulo (Brazil)

2013-03-25

394

8.07 Electromagnetism II, Fall 2002  

E-print Network

Survey of basic electromagnetic phenomena: electrostatics, magnetostatics; electromagnetic properties of matter. Time-dependent electromagnetic fields and Maxwell's equations. Electromagnetic waves, emission, absorption, ...

Zwiebach, Barton

395

Exploring the Electromagnetic Spectrum  

NSDL National Science Digital Library

Students learn the basics of the electromagnetic spectrum and how various types of electromagnetic waves are related in terms of wavelength and energy. In addition, they are introduced to the various types of waves that make up the electromagnetic spectrum including, radio waves, ultraviolet waves, visible light and infrared waves. These topics help inform students before they turn to designing solutions to an overarching engineering challenge question.

2014-09-18

396

"Hearing" Electromagnetic Waves  

NASA Astrophysics Data System (ADS)

In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic waves. Moreover, students learn about the importance and historical development of communication systems, the basic principles of communication links, and the procedure to send information through an electromagnetic wave.1,2

Rojo, Marta; Muñoz, Juan

2014-12-01

397

Meson electromagnetic form factors  

E-print Network

The electromagnetic structure of the pseudoscalar meson nonet is completely described by the sophisticated Unitary&Analytic model, respecting all known theoretical properties of the corresponding form factors.

Stanislav Dubnicka; Anna Z. Dubnickova

2012-10-23

398

How Strong are Electromagnets?  

NSDL National Science Digital Library

This is an activity about electromagnetism. Using a battery and a length of wire, learners will construct an electromagnet and investigate the number of paperclips the electromagnet can hold for an electromagnet with twenty loops of wire versus one with forty loops of wire. A six to twelve volt battery, a large nail or metal rod, and insulated wire are required for this activity. This is the fourth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

399

Conversion of an Electromagnetic Wave into a Periodic Train of Solitons under Cyclotron Resonance Interaction with a Backward Beam of Unexcited Electron-Oscillators  

NASA Astrophysics Data System (ADS)

The possibility of the conversion of intense continuous microwave radiation into a periodic train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons.

Zotova, I. V.; Ginzburg, N. S.; Sergeev, A. S.; Kocharovskaya, E. R.; Zaslavsky, V. Yu.

2014-10-01

400

Interactions of 200 GeV muons in an electromagnetic streamer tube calorimeter  

Microsoft Academic Search

We have investigated the response of an electromagnetic streamer tube calorimeter to 200 GeV muons. Muons undergo electromagnetic interactions in the absorber plates and produce electrons, photons or electron pairs the energy of which is measured by the calorimeter. Occasionally also catastrophic energy losses occur, so that in these very rare cases muons could even be misinterpreted as electrons.

Rainer Baumgart; Claus Grupen; Hans-Jürgen Meyer; Ulrich Schäfer; Reinhard Werthenbach

1987-01-01

401

Quantum modulation against electromagnetic interference  

E-print Network

Periodic signals in electrical and electronic equipment can cause interference in nearby devices. Randomized modulation of those signals spreads their energy through the frequency spectrum and can help to mitigate electromagnetic interference problems. The inherently random nature of quantum phenomena makes them a good control signal. I present a quantum modulation method based on the random statistics of quantum light. The paper describes pulse width modulation schemes where a Poissonian light source acts as a random control that spreads the energy of the potential interfering signals. I give an example application for switching-mode power supplies and comment the further possibilities of the method.

Juan Carlos Garcia-Escartin

2014-11-26

402

Electromagnetic interference and solid state protective relays  

Microsoft Academic Search

This paper presents new information on the nature of the electromagnetic environment in an electric power station which can influence the performance of modern solid state protective relays and other sensitive electronic control and data processing equipments. Present industry standard tests do not simulate the full range of this environment and may need to be revised. The frequency spectrum of

W. C. Kotheimer; L. L. Mankoff

1977-01-01

403

Electromagnetism Adapted for Life Science Students  

ERIC Educational Resources Information Center

Describes the study of electronics as a terminal course in electromagnetism. A lecture-laboratory approach is used with a strong emphasis on practical experience. Outlines the major topics of the lecture program and describes the activities used in the laboratory. (GS)

Gurr, F. M.; And Others

1974-01-01

404

Conversion of an electromagnetic wave into a periodic train of solitons under cyclotron resonance interaction with a backward beam of unexcited electron-oscillators.  

PubMed

The possibility of the conversion of intense continuous microwave radiation into a periodic train of short pulses by means of resonant interaction with a beam of unexcited cyclotron electron oscillators moving backward is shown. In such a system there is a certain range of parameters where the incident stationary signal splits into a train of short pulses and each of them can be interpreted as a soliton. It is proposed to use this effect for amplitude modulation of radiation of short wavelength gyrotrons. PMID:25325645

Zotova, I V; Ginzburg, N S; Sergeev, A S; Kocharovskaya, E R; Zaslavsky, V Yu

2014-10-01

405

Rigorous Solutions of Electromagnetic Problems Involving Hundreds of Millions  

E-print Network

-of-the-art technology. Hence, many electromagnetic problems in the literature have been solved by resorting to various and radar-eluding stealth airborne targets,radiation from antennas and electronic devices,and transmission

Gürel, Levent

406

IR Spectroscopy Spectroscopy: Branch of science in which light or other electromagnetic radiation  

E-print Network

IR Spectroscopy Spectroscopy: Branch of science in which light or other electromagnetic radiation electromagnetic radiation, such as mass spectroscopy (also called mass spectrometry), or electron spectroscopy. This is a useful approach to study matter, since matter will interact with electromagnetic radiation to absorb

Sherrill, David

407

Electromagnetic Environment Measurement under Steady-State Conditions in Utility Substations  

Microsoft Academic Search

Electrical power substations use to be characterized as powerful electromagnetic environments. Electric and magnetic fields are generated during all operational conditions, even under steady-state system operation and can damage installed sensitive electronic devices. In this paper a pilot-substation is evaluated in order to verify how electromagnetic fields are distributed inside its installation. Steady state electromagnetic fields are evaluated. Grounding integrity

Cristina de Abreu Silveira; Caiuby Alves da Costa; R. da Costa e Silva; L. R. Soares; J. C. P. Guimaraes

2006-01-01

408

NISTHB 150-11 Electromagnetic  

E-print Network

NISTHB 150-11 NVLAP Electromagnetic Compatibility and Telecommunications Bethany Hackett Bradley. #12;NISTHB 150-11 NVLAP Electromagnetic Compatibility and Telecommunications Bethany Hackett Bradley Programs Dennis Camell Electromagnetics Division Physical Measurement Laboratory http://dx.doi.org/10

409

Venus rack cooling system  

SciTech Connect

A rack cooling system for the VENUS detector has been developed. It uses forced-air cooling and has enough cooling power for crates with as much as 1500 watts of power consumption. The design and the cooling performance for FASTBUS crates are reported.

Tanaka, R.; Arai, Y.; Ishihara, N.

1986-02-01

410

Hybrid methods for mixed signal circuits subject to on & off - board electromagnetic interference.  

E-print Network

??Electromagnetic Interference (EMI) disrupting operations of electronic systems has been studied for decades. Many theoretical techniques and protection mechanisms are proposed to reduce impact of… (more)

Bayram, Yakup

2006-01-01

411

Building an Electromagnet  

NSDL National Science Digital Library

Students design and construct an electromagnet that must pick up 10 staples. They begin with only minimal guidance, and after the basic concept is understood, are informed of the properties that affect the strength of that magnet. They conclude by designing their own electromagnet to complete the challenge of separating scrap steel from scrap aluminum for recycling and share it with the class.

Vu Bioengineering Ret Program

412

Electromagnetic Wave Dynamics in  

E-print Network

possibilities for strong localization of electromagnetic radiation in a dense and ultracold atomic gas sample the localization of light in ultracold samples of gas-phase Rb atoms has, until now, been focused on lightMesoscopic Electromagnetic Wave Dynamics in Ultracold Atomic Gases Robin Kaiser and Mark D. Havey

413

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This tutorial introduces students to the concepts of electromagnetic waves, wavelength, and the electromagnetic spectrum. Diagrams and written descriptions explain how wavelength is measured and explore the traditional divisions of the spectrum: radio, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

414

Electromagnetic Analysis: Concrete Results  

Microsoft Academic Search

Abstract Although the possibility of attacking smart - cards by analyz - ing their electromagnetic power radiation repeatedly appears in research papers, all accessible references evade the essence of reporting conclusive experiments where actual cryptographic algorithms such as des or rsa were successfully attacked This work describes electromagnetic experiments conducted on three dif - ferent cmos chips, featuring di erent

Karine Gandolfi; Christophe Mourtel; Francis Olivier

2001-01-01

415

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This is a lesson about the electromagnetic spectrum. Learners will read two pages of information about the electromagnetic spectrum and answer questions in an accompanying worksheet. This activity is from the Stanford Solar Center's All About the Sun: Sun and Stars activity guide for Grades 5-8 and can also accompany the Stanford Solar Center's Build Your Own Spectroscope activity.

416

SMILE Lab: Electromagnets  

NSDL National Science Digital Library

This site contains instructions for a fairly simple lab or demonstration using electromagnets. The electromagnets are made with nails, copper wire, and batteries. The lab includes a list of needed materials, the procedure that the students should follow, and a brief discussion of the physical concepts involved.

Johnson, Porter

2006-07-18

417

Introducing Electromagnetic Field Momentum  

ERIC Educational Resources Information Center

I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

Hu, Ben Yu-Kuang

2012-01-01

418

Electromagnetic interference in balanced converters .  

E-print Network

??In this dissertation, an investigation into reducing Electromagnetic Interference (EMI) through design is presented. Root generation mechanisms of Electromagnetic Interference are often neglected during the… (more)

Burford, Steven Trefor

2014-01-01

419

Constraining scenarios of the soft/hard transition for the pion electromagnetic form factor with expected data of 12-GeV Jefferson Lab experiments and of the Electron-Ion Collider  

E-print Network

It has been shown previously [PRD 88 (2013) 093005, arXiv:1310.1770] that a non-perturbative relativistic constituent-quark model for the $\\pi$-meson electromagnetic form factor allows for a quantitative description of the soft/hard transition, resulting in the correct Quantum-Chromodynamical asymptotics, including normalization, from the low-energy data without further parameter tuning. This happens universally whenever the constituent-quark mass is switched off. The energy range where the transition happens is therefore determined by the quark-mass running at intermediate energies and is not tightly constrained theoretically. Here we consider possible ways to pin down this energy range with coming experimental data. We demonstrate that expected experimental uncertainties of the 12-GeV Jefferson-Lab data are larger than the span of predictions of the model, so these data might be used for testing the model but not for determination of the soft/hard transition scale. Contrary, the projected Electron-Ion Colli...

Troitsky, S V

2015-01-01

420

Jet-cooled laser-induced fluorescence spectroscopy of cyclohexoxy: rotational and fine structure of molecules in nearly degenerate electronic States.  

PubMed

The rotational structure of the previously observed B?(2)A' ? X?(2)A? and B?(2)A' ? Ã(2)A' laser-induced fluorescence spectra of jet-cooled cyclohexoxy radical (c-C6H11O) [ Zu, L.; Liu, J.; Tarczay, G.; Dupré, P; Miller, T. A. Jet-cooled laser spectroscopy of the cyclohexoxy radical. J. Chem. Phys. 2004 , 120 , 10579 ] has been analyzed and simulated using a spectroscopic model that includes the coupling between the nearly degenerate X? and à states separated by ?E. The rotational and fine structure of these two states is reproduced by a 2-fold model using one set of molecular constants including rotational constants, spin-rotation constants (?'s), the Coriolis constant (A?t), the quenched spin-orbit constant (a?ed), and the vibronic energy separation between the two states (?E0). The energy level structure of both states can also be reproduced using an isolated-state asymmetric top model with rotational constants and effective spin-rotation constants (?'s) and without involving Coriolis and spin-orbit constants. However, the spin-orbit interaction introduces transitions that have no intensity using the isolated-state model but appear in the observed spectra. The line intensities are well simulated using the 2-fold model with an out-of-plane (b-) transition dipole moment for the B? ? X? transitions and in-plane (a and c) transition dipole moment for the B? ? à transitions, requiring the symmetry for the X? (Ã) state to be A? (A'), which is consistent with a previous determination and opposite to that of isopropoxy, the smallest secondary alkoxy radical. The experimentally determined Ã-X? separation and the energy level ordering of these two states with different (A' and A?) symmetries are consistent with quantum chemical calculations. The 2-fold model also enables the independent determination of the two contributions to the Ã-X? separation: the relativistic spin-orbit interaction (magnetic effect) and the nonrelativistic vibronic separation between the lowest vibrational energy levels of these two states due to both electrostatic interaction (Coulombic effect) and difference in zero-point energies (kinetic effect). PMID:25054559

Liu, Jinjun; Miller, Terry A

2014-12-26

421

The state of the art in hadron beam cooling  

SciTech Connect

Cooling of hadron beams (including heavy-ions) is a powerful technique by which accelerator facilities around the world achieve the necessary beam brightness for their physics research. In this paper, we will give an overview of the latest developments in hadron beam cooling, for which high energy electron cooling at Fermilab's Recycler ring and bunched beam stochastic cooling at Brookhaven National Laboratory's RHIC facility represent two recent major accomplishments. Novel ideas in the field will also be introduced.

Prost, L.R.; Derwent, P.; /Fermilab

2008-09-01

422

Electromagnetic Observables in Few-Nucleon Systems  

E-print Network

The electromagnetic probe is a very valuable tool to study the dynamics of few nucleons. It can be very helpful in shedding light on the not yet fully understood three-nucleon forces. We present an update on the theoretical studies of electromagnetic induced reactions, such as photo-disintegration and electron scattering off 4He. We will show that they potentially represent a tool to discriminate among three-nucleon forces. Then, we will discuss the charge radius and the nuclear electric polarizability of the 6He halo nucleus.

Sonia Bacca

2012-10-10

423

Electromagnetic Containerless Processing Facility TEMPUS (Tiegelfreies Elektromagnetisches  

NASA Technical Reports Server (NTRS)

TEMPUS, an electromagnetic levitation facility that allows containerless processing of metallic samples in microgravity, first flew on the IML-2 Spacelab mission. The principle of electromagnetic levitation is used commonly in ground-based experiments to melt and then cool metallic melts below their freezing points without solidification occurring. The TEMPUS operation is controlled by its own microprocessor system; although commands may be sent remotely from the ground and real time adjustments may be made by the crew. Two video cameras, a two-color pyrometer for measuring sample temperatures, and a fast infrared detector for monitoring solidification spikes, will be mounted to the process chamber to facilitate observation and analysis. In addition, a dedicated high-resolution video camera can be attached to the TEMPUS to measure the sample volume precisely.

1994-01-01

424

Amplified Thermionic Cooling Using Arrays of Nanowires  

NASA Technical Reports Server (NTRS)

A class of proposed thermionic cooling devices would incorporate precise arrays of metal nanowires as electron emitters. The proposed devices could be highly miniaturized, enabling removal of heat from locations, very close to electronic devices, that have previously been inaccessible for heat-removal purposes. The resulting enhancement of removal of heat would enable operation of the devices at higher power levels and higher clock speeds. Moreover, the mass, complexity, and bulk of electronic circuitry incorporating these highly miniaturized cooling devices could be considerably reduced, relative to otherwise equivalent circuitry cooled by conventional electromechanical, thermoelectric, and fluidic means. In thermionic cooling, one exploits the fact that because only the highest-energy electrons are thermionically emitted, collecting those electrons to prevent their return to the emitting electrode results in the net removal of heat from that electrode. Collection is effected by applying an appropriate positive bias potential to another electrode placed near the emitting electrode. The concept underlying the proposal is that the thermionic-emission current and, hence, the cooling effect attainable by use of an array of nanowires could be significantly greater than that attainable by use of a single emitting electrode or other electron- emitting surface. The wires in an array according to the proposal would protrude perpendicularly from a planar surface and their heights would be made uniform to within a sub-nanometer level of precision

Yang, Eui-Hyeok; Choi, Daniel; Shcheglov, Kirill; Hishinuma, Yoshikazu

2007-01-01

425

Towards realistic parametrization of the kinetic anisotropy and the resulting instabilities in space plasmas. Electromagnetic electron-cyclotron instability in the solar wind  

NASA Astrophysics Data System (ADS)

Measured in situ, the particle velocity distributions in the solar wind plasma reveal two distinct components: a Maxwellian (thermal) core, and a less dense but hotter suprathermal halo with a power-law distribution described by Lorentzian/Kappa distribution function. Despite this evidence, the existing attempts to parametrize anisotropic distributions and the resulting wave instabilities are limited to idealized models, which either ignore the suprathermal populations, or minimize the core, assuming it is cold. Here, a more realistic approach is identified, combining an isotropic Maxwellian core and an anisotropic bi-Kappa halo. This model is relevant at large heliocentric distances and for the slow winds, when the field-aligned strahl is less pronounced and kinetic energy densities in the core and halo are comparable. A comparative study with the cold-core-based model is performed on the electron whistler-cyclotron instability driven by the anisotropic halo. Derived exactly numerically, the instability thresholds and growth rates confirm the expectation that cyclotron instabilities are inhibited by the core thermal spread. This effect is enhanced by the increase of the halo-core relative density with heliocentric distance, suggesting that local conditions for this instability to develop at large radial distances in the solar wind are less favourable than predicted before.

Lazar, M.; Poedts, S.; Schlickeiser, R.; Dumitrache, C.

2015-01-01

426

I. What is electromagnetic radiation and the electromagnetic spectrum?  

E-print Network

i­1 I. What is electromagnetic radiation and the electromagnetic spectrum? What do light, X effects on matter. This "stuff" is called electromagnetic radiation, because it travels (radiates) and has electrical and magnetic effects. Electromagnetic radiation is the means for many of our interactions

Sitko, Michael L.

427

A Review of Cooling in Microchannels  

Microsoft Academic Search

Advancements in electronic performance result in a decrease in device size and increase in power density. Because of these advancements, current cooling mechanisms for electronic devices are beginning to be ineffective. Within the localized hot spots, the materials of the components are reaching temperature values that can lead to improper functioning of the device. Many techniques have been successful in

Jami F. Tullius; Robert Vajtai; Yildiz Bayazitoglu

2011-01-01

428

Equilibrium temperature of laser cooled atoms in squeezed vacuum  

NASA Technical Reports Server (NTRS)

It is shown that by squeezing the vacuum fluctuations of the electromagnetic field the quantum fluctuations of the optical forces exerted on laser cooled two-level atoms, can be dramatically modified. Under certain conditions, this modification in concert with the enhanced average forces can lead to equilibrium temperatures below those attained under normal vacuum fluctuations.

Shevy, Y.

1992-01-01

429

Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet  

NASA Technical Reports Server (NTRS)

In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

Scully, Robert

2012-01-01

430

Imagine the Universe: Electromagnetic Spectrum - Introduction  

NSDL National Science Digital Library

This is a beginning tutorial on the electromagnetic spectrum. It was developed by the Imagine the Universe project through NASA's Goddard Space Flight Center. It contains readable explanations of each type of radiation on the EM spectrum, a short quiz, and related "Cool Facts". It was designed to supplement lesson plans and activities created by the same team. See Related items below for links to lesson plans and other resources. This item is part of a larger collection of K-12 resources created by the High Energy Astrophysics Science Archive Research Center for NASA.

Lochner, Jim

2008-09-24

431

LBT adaptive secondary electronics  

NASA Astrophysics Data System (ADS)

The adaptive secondary mirror is a fundamental part in the LBT adaptive optics architecture. The thin, continuous mirror is controlled by 672 electromagnetic actuators (voice coil motors) with local position feedback (capacitive sensor) and allows to perform from tip-tilt to high order wavefront correction, but also chopping. The adaptive secondary is controlled by a DSP-based dedicated electronics. The control electronics does not only implement the mirror position control tasks, but does also realize the Real Time Reconstructor (RTR). The control system, while maintaining a similar architecture to the MMT adaptive secondary one, shows a substantial enhancement in terms of computational power, rising in the range of hundreds of Gigaflops. This allows to minimize the computational time required to apply the wavefront correction pattern from the wavefront sensor acquisition, even in case of high order reconstructor dynamics. The electronics is housed in compact cooled crates placed in the adaptive secondary hub. Apart from the power supply lines, it is connected to the other components of the adaptive control system just through a very high speed fiber optic link, capable of 2.9 Gigabit/s of actual data throughput. The control system has been designed according to modular concept, so that the number of channels can be easily increased or reduced for adapting the electronics to different correctors. A substantial effort has been dedicated to the flexibility and on-field configurability of system. In this frame, the same electronics (or part of it) can be easily adapted to become the building block for the data processing unit required for Multi-Conjugated Adaptive Optics

Biasi, Roberto; Andrighettoni, Mario; Veronese, Daniele; Biliotti, Valdemaro; Fini, Luca; Riccardi, Armando; Mantegazza, Paolo; Gallieni, Daniele

2003-02-01

432

Electromagnetic Radiations as a Fluid Flow  

E-print Network

We combine Maxwell's equations with Eulers's equation, related to a velocity field of an immaterial fluid, where the density of mass is replaced by a charge density. We come out with a differential system able to describe a relevant quantity of electromagnetic phenomena, ranging from classical dipole waves to solitary wave-packets with compact support. The clue is the construction of an energy tensor summing up both the electromagnetic stress and a suitable mass tensor. With this right-hand side, explicit solutions of the full Einstein's equation are computed for a wide class of wave phenomena. Since our electromagnetic waves may behave and interact exactly as a material fluid, they can create vortex structures. We then explicitly analyze some vortex ring configurations and examine the possibility to build a model for the electron.

Daniele Funaro

2009-11-25

433

Electromagnetic properties of viscous charged fluids  

E-print Network

We provide a general theoretical framework to describe the electromagnetic properties of viscous charged fluids, consisting for example of electrons in certain solids or plasmas. We confirm that finite viscosity leads to multiple modes of evanescent electromagnetic waves at a given frequency, one of which is characterized by a negative index of refraction, as previously discussed in a simplified model by one of the authors. In particular we explain how optical spectroscopy can be used to probe the viscosity. We concentrate on the impact of this on the coefficients of refraction and reflection at the sample-vacuum interface. Analytical expressions are obtained relating the viscosity parameter to the reflection and transmission coefficients of light. We demonstrate that finite viscosity has the effect to decrease the reflectivity of a metallic surface, while the electromagnetic field penetrates more deeply. While on a phenomenological level there are similarities to the anomalous skin effect, the model presente...

Forcella, Davide; Valentinis, Davide; van der Marel, Dirk

2014-01-01

434

The classical geometrization electromagnetism  

E-print Network

Following the line of the history, if by one side the electromagnetic theory was consolidated on the 19th century, the emergence of the special and the general relativity theories on the 20th century opened possibilities of further developments, with the search for the unification of the gravitation and the electromagnetism on a single unified theory. Some attempts to the geometrization of the electromagnetism emerged in this context, where these first models resided strictly on a classical basis. Posteriorly, they were followed by more complete and embracing quantum field theories. The present work reconsiders the classical viewpoint, with the purpose of showing that in a first order of approximation the electromagnetism constitutes a geometric structure aside other phenomena as gravitation. Even though being limited, the model is consistent and offers the possibility of an experimental test of validity.

C. A. Duarte

2015-02-11

435

Inverse problems in electromagnetics  

E-print Network

Two inverse problems in electromagnetics are investigated in this thesis. The first is the retrieval of the effective constitutive parameters of metamaterials from the measurement of the reflection and the transmission ...

Chen, Xudong, 1977-

2005-01-01

436

Electromagnetism in the Movies.  

ERIC Educational Resources Information Center

Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

Everitt, Lori R.; Patterson, Evelyn T.

1999-01-01

437

Purely electromagnetic spacetimes  

E-print Network

Electrovacuum solutions devoid of usual mass sources are classified in the case of one, two and three commuting Killing vectors. Three branches of solutions exist. Electromagnetically induced mass terms appear in some of them.

B. V. Ivanov

2007-12-15

438

An opening electromagnetic transducer  

NASA Astrophysics Data System (ADS)

Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

Sun, Yanhua; Kang, Yihua

2013-12-01

439

Electromagnetic rotational actuation.  

SciTech Connect

There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

Hogan, Alexander Lee

2010-08-01

440

Rock drilling, cooling liquids  

NSF Publications Database

Title : Rock drilling, cooling liquids Type : Antarctic EAM NSF Org: OD / OPP Date : October 23 ... impacts that could accrue from the use of cooling liquids during rock drilling. Our discussion of ...

441

Cooling Water System Optimization  

E-print Network

During summer months, many manufacturing plants have to cut back in rates because the cooling water system is not providing sufficient cooling to support higher production rates. There are many low/no-cost techniques available to improve tower...

Aegerter, R.

2005-01-01

442

Photocurrent measurements of supercollision cooling in graphene  

NASA Astrophysics Data System (ADS)

The cooling of hot electrons in graphene is the critical process underlying the operation of exciting new graphene-based optoelectronic and plasmonic devices, but the nature of this cooling is controversial. We extract the hot-electron cooling rate near the Fermi level by using graphene as a novel photothermal thermometer that measures the electron temperature (T(t)) as it cools dynamically. We find the photocurrent generated from graphene p-n junctions is well described by the energy dissipation rate CdT/dt=-A(T3-Tl3), where the heat capacity is C=?T and Tl is the base lattice temperature. These results are in disagreement with predictions of electron-phonon emission in a disorder-free graphene system, but in excellent quantitative agreement with recent predictions of a disorder-enhanced supercollision cooling mechanism. We find that the supercollision model provides a complete and unified picture of energy loss near the Fermi level over the wide range of electronic (15 to ~ 3,000K) and lattice (10-295K) temperatures investigated.

Graham, Matt W.; Shi, Su-Fei; Ralph, Daniel C.; Park, Jiwoong; McEuen, Paul L.

2013-02-01

443

Radial turbine cooling  

NASA Technical Reports Server (NTRS)

The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

Roelke, Richard J.

1992-01-01

444

Fast optical cooling of nanomechanical cantilever with the dynamical Zeeman effect  

E-print Network

We propose an efficient optical electromagnetically induced transparency (EIT) cooling scheme for a cantilever with a nitrogen-vacancy center attached in a non-uniform magnetic field using dynamical Zeeman effect. In our scheme, the Zeeman effect combined with the quantum interference effect enhances the desired cooling transition and suppresses the undesired heating transitions. As a result, the cantilever can be cooled down to nearly the vibrational ground state under realistic experimental conditions within a short time. This efficient optical EIT cooling scheme can be reduced to the typical EIT cooling scheme under special conditions.

Jian-Qi Zhang; Shuo Zhang; Jin-Hua Zou; Liang Chen; Wen Yang; Yong Li; Mang Feng

2013-07-15

445

Fast optical cooling of nanomechanical cantilever with the dynamical Zeeman effect.  

PubMed

We propose an efficient optical electromagnetically induced transparency (EIT) cooling scheme for a cantilever with a nitrogen-vacancy center attached in a non-uniform magnetic field using dynamical Zeeman effect. In our scheme, the Zeeman effect combined with the quantum interference effect enhances the desired cooling transition and suppresses the undesired heating transitions. As a result, the cantilever can be cooled down to nearly the vibrational ground state under realistic experimental conditions within a short time. This efficient optical EIT cooling scheme can be reduced to the typical EIT cooling scheme under special conditions. PMID:24514521

Zhang, Jian-Qi; Zhang, Shuo; Zou, Jin-Hua; Chen, Liang; Yang, Wen; Li, Yong; Feng, Mang

2013-12-01

446

Controlled Rate Cooling  

Technology Transfer Automated Retrieval System (TEKTRAN)

Controlled-rate cooling is one of several techniques available for the long-term storage of plants in liquid nitrogen. In this technique samples are slowly cooled to an intermediate temperature and then plunged in liquid nitrogen. Controlled rate cooling is based on osmotic regulation of cell conte...

447

Stochastic cooling in RHIC  

SciTech Connect

After the success of longitudinal stochastic cooling of bunched heavy ion beam in RHIC, transverse stochastic cooling in the vertical plane of Yellow ring was installed and is being commissioned with proton beam. This report presents the status of the effort and gives an estimate, based on simulation, of the RHIC luminosity with stochastic cooling in all planes.

Brennan,J.M.; Blaskiewicz, M. M.; Severino, F.

2009-05-04

448

Head cooling and heat  

Microsoft Academic Search

The effects of head and body cooling during hyperthermia were investigated to determine whether head cooling alone would overcome some of the problems of heat stress. Measurements of body temperature, heart rate, psychomotor performance and subjective comfort were made during cycles of head and body heating and cooling. Heart rates were highest with head and body heating, less with head

D. C. Reader; S. A. Nunneley; R. J. Maldonado

2009-01-01

449

Electromagnetic Effects in SDF Explosions  

SciTech Connect

The notion of high ion and electron concentrations in the detonation of aluminized explosive mixtures has aroused some interest in electro-magnetic effects that the SDF charges might generate when detonated. Motivated by this interest we have started to investigate whether significant electro-magnetic effects show up in our small-scale experiments. However, the design of instrumentation for this purpose is far from straightforward, since there are a number of open questions. Thus the main aim of the feasibility tests is to find - if possible - a simple and reliable method that can be used as a diagnostic tool for electro-magnetic effects. SDF charges with a 0.5-g PETN booster and a filling of 1 g aluminum flakes have been investigated in three barometric bomb calorimeters with volumes ranging from 6.3 l to of 6.6 l. Though similar in volume, the barometric bombs differed in the length-to-diameter ratio. The tests were carried out with the bombs filled with either air or nitrogen at ambient pressure. The comparison of the test in air to those in nitrogen shows that the combustion of TNT detonation products or aluminum generates a substantial increase of the quasi-steady overpressure in the bombs. Repeated tests in the same configuration resulted in some scatter of the experimental results. The most likely reason is that the aluminum combustion in most or all cases is incomplete and that the amount of aluminum actually burned varies from test to test. The mass fraction burned apparently decreases with increasing aspect ratio L/D. Thus an L/D-ratio of about 1 is optimal for the performance of shock-dispersed-fuel combustion. However, at an L/D-ratio of about 5 the combustion still yields appreciable overpressure in excess of the detonation. For a multi-burst scenario in a tunnel environment with a number of SDF charges distributed along a tunnel section a spacing of 5 tunnel diameter and a fuel-specific volume of around 7 l/g might provide an acceptable compromise between optimizing the combustion performance and keeping the number of elementary charges low. Further tests in a barometric bomb calorimeter of 21.2 l volume were performed with four types of aluminum. The mass fraction burned in this case appeared to depend on the morphology of the aluminum particles. Flake aluminum exhibited a better performance than granulated aluminum with particle sizes ranging from below 25 {micro}m to 125 {micro}m for the coarsest material. In addition, a feasibility study on electro-magnetic effects from SDF charges detonated in a tunnel has been performed. A method was developed to measure the local, unsteady electro-conductivity in the detonation/combustion products cloud. This method proved to yield reproducible results. A variety of methods were tested with regard to probing electro-magnetic pulses from the detonation of SDF charges. The results showed little reproducibility and were small compared to the effect from pulsed high voltage discharges of comparatively small energy (around 32 J). Thus either no significant electromagnetic pulse is generated in our small-scale tests or the tested techniques have to be discarded as too insensitive or too limited in bandwidth to detect possibly very high frequency electro-magnetic disturbances.

Reichenbach, H; Neuwald, P; Kuhl, A L

2010-02-12

450

Shock waves in charge-varying dusty plasmas and the effect of electromagnetic radiation  

Microsoft Academic Search

Nonlinear electrostatic wave structures in dusty plasmas in the presence of electromagnetic radiation are investigated. The dust charge variation is assumed to be caused by microscopic electron and ion currents at the grains as well as photoelectric current of electrons. Calculations of electromagnetic radiation effects are performed for the case of solar radiation spectrum in the vicinity of the earth.

S. I. Popel; A. A. Gisko; A. P. Golub; T. V. Losseva; R. Bingham; P. K. Shukla

2000-01-01

451

FOURFOUR--QUADRANT POWER SUPPLIESQUADRANT POWER SUPPLIES FOR STEERING ELECTROMAGNETSFOR STEERING ELECTROMAGNETS  

E-print Network

ELECTROMAGNETS FOR ELECTRONFOR ELECTRON--POSITRON COLLIDERPOSITRON COLLIDER O.O. BelikovBelikov V.V. KozakKozak A ELECTROMAGNETS FOR ELECTRONFOR ELECTRON--POSITRON COLLIDERPOSITRON COLLIDER O.O. BelikovBelikov V.V. KozakKozak A

Kozak, Victor R.

452

Kinetic Energy Harvesting Using Piezoelectric and Electromagnetic Technologies—State of the Art  

Microsoft Academic Search

This paper presents the latest progress in kinetic energy harvesting for wide applications ranging from implanted devices and wearable electronic devices to mobile electronics and self-powered wireless network nodes. The advances in energy harvesters adopting piezoelectric and electromagnetic transduction mechanisms are presented. Piezoelectric generators convert mechanical strain on the active material to electric charge while electromagnetic generators make use of

Alireza Khaligh; Peng Zeng; Cong Zheng

2010-01-01

453

Basic Electronics Tutorials  

NSDL National Science Digital Library

This site gives a number of tutorials and information to help students and instructors develop a knowledge and understanding of the basics of Electronics. Topics include amplifiers, inductors, capacitors, electromagnetism, transformers, transistors and more.

Storr, Wayne

454

Coupling of Gravitation and Electromagnetism in the Weak Field Approximation  

E-print Network

Using the weak field approximation, we can express the theory of general relativity in a Maxwell-type structure comparable to electromagnetism. We find that every electromagnetic field is coupled to a gravitoelectric and gravitomagnetic field. Acknowledging the fact that both fields originate from the same source, the particle, we can express the magnetic and electric field through their gravitational respective analogues using the proportionality coefficient k. This coefficient depends on the ratio of mass and charge and the ratio between the electromagnetic and gravitic-gravitomagnetic permittivity and permeability respectively. Although the coefficient is very small, the fact that electromagnetic fields in material media can be used to generate gravitational and gravitomagnetic fields and vice versa is not commonly known. We find that the coupling coefficient can be increased by massive ion currents, electron and nuclear spin-alignment. Advances in material sciences, cryogenic technology and high frequency electromagnetic fields in material media may lead to applications of the derived relationships.

M. Tajmar; C. de Matos

2000-03-03

455

Electromagnetically Induced Transparency from a Single Atom in Free Space  

E-print Network

We report an absorption spectroscopy experiment and the observation of electromagnetically induced transparency from a single trapped atom. We focus a weak and narrowband Gaussian light beam onto an optically cooled Barium ion using a high numerical aperture lens. Extinction of this beam is observed with measured values of up to 1.3 %. We demonstrate electromagnetically induced transparency of the ion by tuning a strong control beam over a two-photon resonance in a three-level lambda-type system. The probe beam extinction is inhibited by more than 75 % due to population trapping.

L. Slodicka; G. Hetet; S. Gerber; M. Hennrich; R. Blatt

2010-05-18

456

JPRS report: Science and technology. USSR: Electronics and electrical engineering  

NASA Astrophysics Data System (ADS)

s of research in electronics and electrical engineering are given. Research in broadcasting, consumer electronics, antennas, radio wave propagation, reliability, industrial electronics, electron devices, computers, microwave theory and techniques, electromagnetic compatibility, power engineering, electromagnetic fields, quantum electronics and solid state circuits is covered.

1990-03-01

457

Electromagnetic fields and health outcomes.  

PubMed

Over the past two decades, there has been increasing interest in the biological effects and possible health outcomes of weak, low-frequency electric and magnetic fields. Epidemiological studies on magnetic fields and cancer, reproduction and neurobehavioural reactions have been presented. More recently, neurological, degenerative and heart diseases have also been reported to be related to such electromagnetic fields. Furthermore, the increased use of mobile phones worldwide has focussed interest on the possible effects of radiofrequency fields of higher frequencies. In this paper, a summary is given on electromagnetic fields and health outcomes and what policy is appropriate--"no restriction to exposure", "prudent avoidance" or "expensive interventions"? The results of research studies have not been unambiguous; studies indicating these fields as being a health hazard have been published and so were studies indicating no risk at all. In "positive" studies, different types of effects have been reported despite the use of the same study design, e.g., in epidemiological cancer studies. There are uncertainties as to exposure characteristics, e.g., magnetic field frequency and exposure intermittence, and not much is known about possible confounding or effect-modifying factors. The few animal cancer studies reported have not given much help in risk assessment; and in spite of a large number of experimental cell studies, no plausible and understandable mechanisms have been presented by which a carcinogenic effect could be explained. Exposure to electromagnetic fields occurs everywhere: in the home, at work, in school, etc. Wherever there are electric wires, electric motors and electronic equipment, electromagnetic fields are created. This is one of the reasons why exposure assessment is difficult. For epidemiologists, the problems is not on the effect side as registers of diseases exist in many countries today. The problem is that epidemiologists do not know the relevant exposure characteristics to be used in their studies. In international guidelines, limits for restrictions of field exposure are several orders of magnitude above what can be measured from overhead power lines and found in "electrical" occupations. These guidelines emphasize that the state of scientific knowledge today does not warrant limiting exposure levels for the public and the work force, and that further data are required to confirm whether health hazards are present. In some countries, however, the "principle of caution" or "prudent avoidance" has been adopted; meaning the low-cost avoidance of unnecessary exposure as long as there is scientific uncertainty about its health effects. PMID:11603131

Knave, B

2001-09-01

458

Extending the limits of air cooling with thermoelectrically enhanced heat sinks  

Microsoft Academic Search

The prospects of using thermoelectric coolers (TECs) as a means to enhance heat sink performance and extend the limits of air cooling for electronics has considerable appeal when one considers the alternatives of liquid cooling. Historical analyses of TECs for electronics cooling only considered \\

Jim Bierschenk; Dwight Johnson

2004-01-01

459

Ionization in a quantized electromagnetic field  

SciTech Connect

An analytical expression for a matrix element of the transition from a bound state of an electron in an atom to continuum states is obtained by solving the problem of interaction of the electron with a quantized electromagnetic field. This expression is used to derive formulas for the photoelectron spectrum and the rate of ionization of the simplest model atomic system upon absorption of an arbitrary number of photons. The expressions derived are analyzed and compared with the corresponding relationships obtained via other approaches. It is demonstrated that there are differences as compared to the case of the classical field. In particular, the photoelectron spectrum exhibits dips due to the destructive interference of the transition amplitudes in the quantized electromagnetic field.

Gonoskov, I. A., E-mail: gonoskov@ufp.appl.sci-nnov.ru; Vugalter, G. A.; Mironov, V. A. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

2007-12-15

460

Inverter power module with distributed support for direct substrate cooling  

DOEpatents

Systems and/or methods are provided for an inverter power module with distributed support for direct substrate cooling. An inverter module comprises a power electronic substrate. A first support frame is adapted to house the power electronic substrate and has a first region adapted to allow direct cooling of the power electronic substrate. A gasket is interposed between the power electronic substrate and the first support frame. The gasket is configured to provide a seal between the first region and the power electronic substrate. A second support frame is adapted to house the power electronic substrate and joined to the first support frame to form the seal.

Miller, David Harold (San Pedro, CA); Korich, Mark D. (Chino Hills, CA); Ward, Terence G. (Redondo Beach, CA); Mann, Brooks S. (Redondo Beach, CA)

2012-08-21

461

Electromagnetic properties of baryons  

SciTech Connect

We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M. [Institut fuer Kernphysik, Universitaet Mainz, D-55099 Mainz (Germany); Martin-Camalich, J. [Departamento de Fisica Teorica and IFIC, Universidad de Valencia-CSIC, Spain and Department of Physics and Astronomy, University of Sussex, BN1 9Qh, Brighton (United Kingdom)

2011-10-21

462

Stochastic cooling in RHIC  

SciTech Connect

The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.

Brennan J. M.; Blaskiewicz, M.; Mernick, K.

2012-05-20

463

Nonlinear electromagnetic excitation of ultrasound in metals  

NASA Astrophysics Data System (ADS)

The nonlinear electromagnetic generation of longitudinal ultrasound under anomalous skin effect conditions is investigated theoretically. It is shown that, in the weak nonlinear regime, deformation force serves as the main source of excitation of double-frequency acoustic oscillations. This generation mechanism is related, on the one hand, to the strong spatial inhomogeneity of the electron distribution function, and, on the other, to the presence of a Lorentz force which is due to the magnetic field of the wave.

Vasilev, A. N.; Gulianskii, M. A.; Kaganov, M. I.

1986-07-01

464

Electromagnetic wave scattering in dusty plasmas  

NASA Astrophysics Data System (ADS)

The cross section for transition scattering of electromagnetic waves on charged dust particles in a plasma is calculated. For the case of nonlinear screening of the charged dust by the plasma particles, numerical and analytical results are presented, showing a significant enhancement, proportional to the square of the grain surface charge, in the cross section with respect to scattering by free electrons. The effect is independent of the sign of the charge for wavelengths larger than the Debye length.

Bingham, R.; de Angelis, U.; Tsytovich, V. N.; Havnes, O.

1991-03-01

465

Electromagnetic propulsion test facility  

NASA Technical Reports Server (NTRS)

A test facility for the exploration of electromagnetic propulsion concept is described. The facility is designed to accommodate electromagnetic rail accelerators of various lengths (1 to 10 meters) and to provide accelerating energies of up to 240 kiloJoules. This accelerating energy is supplied as a current pulse of hundreds of kiloAmps lasting as long as 1 millisecond. The design, installation, and operating characteristics of the pulsed energy system are discussed. The test chamber and its operation at pressures down to 1300 Pascals (10 mm of mercury) are described. Some aspects of safety (interlocking, personnel protection, and operating procedures) are included.

Gooder, S. T.

1984-01-01

466

Improved Electromagnetic Brake  

NASA Technical Reports Server (NTRS)

A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may still be possible to set the brake by applying an electromagnet current to aid the permanent magnetic field instead of canceling it, this action can mask an out-of-tolerance condition in the brake and it does not restore the fail-safe function of setting the brake when current is lost.

Martin, Toby B.

2004-01-01

467

Electromagnetic power absorber  

NASA Technical Reports Server (NTRS)

A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

Iwasaki, R. S. (inventor)

1979-01-01

468

3. ELECTROMAGNETIC COMPATIBILITY Abstract --The electromagnetic interference between the  

E-print Network

3. ELECTROMAGNETIC COMPATIBILITY Abstract -- The electromagnetic interference between the electromagnetic fields in 3D, assuming that the field is computed outside a sphere of radius r that contains impedance of the considered environment. - and are the magnetic and electric multipoles, respectively

Paris-Sud XI, Université de

469

Gas turbine cooling system  

DOEpatents

A gas turbine engine (10) having a closed-loop cooling circuit (39) for transferring heat from the hot turbine section (16) to the compressed air (24) produced by the compressor section (12). The closed-loop cooling system (39) includes a heat exchanger (40) disposed in the flow path of the compressed air (24) between the outlet of the compressor section (12) and the inlet of the combustor (14). A cooling fluid (50) may be driven by a pump (52) located outside of the engine casing (53) or a pump (54) mounted on the rotor shaft (17). The cooling circuit (39) may include an orifice (60) for causing the cooling fluid (50) to change from a liquid state to a gaseous state, thereby increasing the heat transfer capacity of the cooling circuit (39).

Bancalari, Eduardo E. (Orlando, FL)

2001-01-01

470

Canceling Electromagnetic Interference During Tests  

NASA Technical Reports Server (NTRS)

Old technique solves modern problem. Simple amplitude-and-phase-cancellation technique removes strong electromagnetic interference from received test signal, enabling recovery of relatively weak signal from device under test. Useful in outdoor tests of devices for electromagnetic compatibility.

Robinson, Paul A., Jr.; Edmonds, Larry D.

1988-01-01

471

8.07 Electromagnetism II, Fall 2005  

E-print Network

This course is the second in a series on Electromagnetism beginning with Electromagnetism I (8.02 or 8.022). It is a survey of basic electromagnetic phenomena: electrostatics; magnetostatics; electromagnetic properties of ...

Bertschinger, Edmund

472

Electromagnetic Radiation REFERENCE: Remote Sensing of  

E-print Network

1 CHAPTER 2: Electromagnetic Radiation Principles REFERENCE: Remote Sensing of the Environment John;2 Electromagnetic Energy Interactions Energy recorded by remote sensing systems undergoes fundamental interactions, creating convectional currents in the atmosphere. c) Electromagnetic energy in the form of electromagnetic

Gilbes, Fernando

473

Electromagnetically Induced Flows Michiel de Reus  

E-print Network

Electromagnetically Induced Flows in Water Michiel de Reus 8 maart 2013 () Electromagnetically Conclusion and future research () Electromagnetically Induced Flows 2 / 56 #12;1 Introduction 2 Maxwell Navier Stokes equations 5 Simulations 6 Conclusion and future research () Electromagnetically Induced

Vuik, Kees

474

Cooling Dry Cows  

E-print Network

T he drop in milk production in the summer causes sig- nificant economic losses in the dairy industry. That decrease in production is brought on by heat stress, and studies have documented that cooling lactat- ing cows increases their milk pro... studies have investigat- ed whether cooling dry cows affects postpartum milk produc- tion and reproductive measures, but the results so far have been inconclusive. In deciding whether to install cooling systems for dry cattle, producers should consider...

Stokes, Sandra R.

2000-07-17

475

S'COOL Flyer  

NSDL National Science Digital Library

This flyer is a two-page overview of the Student Cloud Observations On-Line (S'COOL) education project. It covers the project's educational contributions, societal benefits, educational outgrowths, and scientific findings. The flyer shows the numbers and locations of S'COOL participation and regional observation coverage. It also contains URLs for online resources (e.g., GLOBE contrail education and S-COOL Website).

2005-01-01

476

Heating and cooling  

NSDL National Science Digital Library

Heating and cooling homes and businesses require a major energy commitment. This informational piece, part of a series about the future of energy, introduces students to the energy needed to heat and cool homes and workplaces. Students explore energy requirements in the home and at work and discuss current technologies to improve heating and cooling efficiencies. Articles on heat pumps and solar heating and cooling techniques are accessible from a sidebar. A link to a PBS NewsHour article on air conditioning efficiency and a link to material discussing alternatives to air conditioning are also provided. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

477

Semioptimal practicable algorithmic cooling  

SciTech Connect

Algorithmic cooling (AC) of spins applies entropy manipulation algorithms in open spin systems in order to cool spins far beyond Shannon's entropy bound. Algorithmic cooling of nuclear spins was demonstrated experimentally and may contribute to nuclear magnetic resonance spectroscopy. Several cooling algorithms were suggested in recent years, including practicable algorithmic cooling (PAC) and exhaustive AC. Practicable algorithms have simple implementations, yet their level of cooling is far from optimal; exhaustive algorithms, on the other hand, cool much better, and some even reach (asymptotically) an optimal level of cooling, but they are not practicable. We introduce here semioptimal practicable AC (SOPAC), wherein a few cycles (typically two to six) are performed at each recursive level. Two classes of SOPAC algorithms are proposed and analyzed. Both attain cooling levels significantly better than PAC and are much more efficient than the exhaustive algorithms. These algorithms are shown to bridge the gap between PAC and exhaustive AC. In addition, we calculated the number of spins required by SOPAC in order to purify qubits for quantum computation. As few as 12 and 7 spins are required (in an ideal scenario) to yield a mildly pure spin (60% polarized) from initial polarizations of 1% and 10%, respectively. In the latter case, about five more spins are sufficient to produce a highly pure spin (99.99% polarized), which could be relevant for fault-tolerant quantum computing.

Elias, Yuval [Schulich Faculty of Chemistry, Technion City, Haifa 32000 (Israel); Mor, Tal [Computer Science Department, Technion City, Haifa 32000 (Israel); Weinstein, Yossi [Physics Department, Technion City, Haifa 32000 (Israel)

2011-04-15

478

Passive containment cooling system  

DOEpatents

A containment cooling system utilizes a naturally induced air flow and a gravity flow of water over the containment shell which encloses a reactor core to cool reactor core decay heat in two stages. When core decay heat is greatest, the water and air flow combine to provide adequate evaporative cooling as heat from within the containment is transferred to the water flowing over the same. The water is heated by heat transfer and then evaporated and removed by the air flow. After an initial period of about three to four days when core decay heat is greatest, air flow alone is sufficient to cool the containment.

Conway, Lawrence E. (Robinson Township, Allegheny County, PA); Stewart, William A. (Penn Hills Township, Allegheny County, PA)

1991-01-01

479

Electromagnetic radiations from rocks  

Microsoft Academic Search

To test the possibility of the emission of electromagnetic waves from rocks, experiments have been made to measure the electric field by using mainly granite samples that were struck together or struck by a hammer or a weight and were fractured by a bending moment. The wide-band (10 Hz to 100 kHz) waveforms of electric signals were digitally recorded. Roughly

Toshio Ogawa; Kazuo Oike; Taiji Miura

1985-01-01

480

Simple Superconducting "Permanent" Electromagnet  

NASA Technical Reports Server (NTRS)

Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

Israelson, Ulf E.; Strayer, Donald M.

1992-01-01