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1

Electron CoolingElectron Cooling Sergei Nagaitsev  

E-print Network

Electron CoolingElectron Cooling Sergei Nagaitsev FNAL - AD April 28, 2005 #12;Electron Cooling methods must "get around the theorem" e.g. by pushing phase-space around. #12;Electron Cooling - Nagaitsev 3 TodayToday''s Menus Menu What is cooling? Types of beam cooling Electron cooling Conclusions #12

Fermilab

2

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

3

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; Derbenev, Yaroslav

2009-03-01

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

Power electronics and electromagnetic compatibility  

Microsoft Academic Search

Recently, power electronics has become the dominant factor in the deterioration of the electromagnetic environment, causing declining quality of line power and increasing level of conducted EMI. This paper reviews the fundamentals of EMC in power electronics, including the terminology and categories of EMC, the propagation and generation of low-frequency and high-frequency disturbances, and the various agency regulations. The paper

R. Redl

1996-01-01

6

Electronics and Electromagnetism  

NASA Astrophysics Data System (ADS)

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

Nièpce, J.-C.; Givord, D.

7

Power electronics cooling apparatus  

DOEpatents

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

Sanger, Philip Albert (Monroeville, PA); Lindberg, Frank A. (Baltimore, MD); Garcen, Walter (Glen Burnie, MD)

2000-01-01

8

Direct cooled power electronics substrate  

DOEpatents

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

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

2010-09-14

9

Electron cooling experiments in CSR  

NASA Astrophysics Data System (ADS)

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400 MeV/u 12C6+ and 200 MeV/u 129Xe54+ were stored and cooled in the experimental ring CSRe, and the cooling force was measured in different conditions.

Yang, XiaoDong; Li, Jie; Mao, LiJun; Li, GuoHong; Ma, XiaoMing; Yan, TaiLai; Mao, RuiShi; Yang, JianCheng; Yuan, YouJin; Parkhomchuk, Vasily; Reva, Vladimir

2011-12-01

10

How Electrons consist of Electromagnetic Waves  

E-print Network

In this paper we investigate the connection between electrons and electromagnetic waves. We then propose how electrons could consist of electromagnetic waves. From this proposal we explain why electron-positron annihilation results in only gamma rays being formed, as well as how gamma rays can form electron-positron pairs. 1

Mark A. Newstead; Stephen C. Newstead

2011-01-01

11

Cylindric electron envelope for relativistic electron cooling  

SciTech Connect

Electron cooling requires small angles between the electrons and the cooled particles. In other words, the electron beam has to be of a cylindrical shape in the cooling section. How to satisfy this requirement for a specific case of a relativistic electron beam transport for the Fermilab electron cooling project? In fact, the requirement splits into two parts: for the beam centroid and its envelope. A straight centroid motion means a good field quality and zero initial conditions; this issue is not a subject of this paper. The cylindrical envelope requires proper initial conditions of the envelope at the entrance of the cooler, it is a problem of matching. A specific complex of measurements and calculations aimed at solving this problem is described here.

Burov, A.; Lebedev, V.; /Fermilab

2005-02-01

12

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

13

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

14

Coherent electron cooling demonstration experiment  

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, R.; Trbojevic, D.; Tuozzolo, J.; Wang, G.; Yakimenko, V.; Hutton, A.; Krafft, G.; Poelker, M.; Rimmer, R.; Bruhwiler, D.; Abell, D.T.; Nieter, C.; Ranjbar, V.; Schwartz, B.; Kholopov M.; Shevchenko, O.; McIntosh, P.; Wheelhouse, A.

2011-09-04

15

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

16

Electromagnetic instability in nonuniform resistive electron magnetohydrodynamics  

SciTech Connect

A local dispersion relation for electromagnetic modes in a nonuniform collisional magnetized electron plasma with fixed ion background is derived, taking into account equilibrium magnetic field and pressure gradients, as well as impurity radiation losses. The dispersion relation is then analyzed both analytically as well as numerically. It is found that for a low-{beta} plasma, the principal source for the generation of unstable modes is the impurity radiation loss; whereas for a high-{beta} plasma, the various effects such as the electron streaming, the electron{endash}ion collisions, finite electron thermal conductivity, and impurity radiation losses are shown to be responsible for unstable perturbations. The results should be useful in the interpretation of nonthermal electromagnetic fluctuations in nonuniform collision-dominated magnetoplasmas with impurities. {copyright} {ital 1996 American Institute of Physics.}

Mirza, A.M.; Murtaza, G. [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)] [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Shukla, P.K. [Institut fuer Theoretische Physik, Ruhr Universitaet Bochum, 44780 Bochum (Germany)] [Institut fuer Theoretische Physik, Ruhr Universitaet Bochum, 44780 Bochum (Germany)

1996-03-01

17

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

18

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

19

Sympathetic electromagnetically-induced-transparency laser cooling of motional modes in an ion chain.  

PubMed

We use electromagnetically-induced-transparency laser cooling to cool motional modes of a linear ion chain. As a demonstration, we apply electromagnetically-induced-transparency cooling on 24Mg+ ions to cool the axial modes of a 9Be+-24Mg+ ion pair and a 9Be+-24Mg+-24Mg+-9Be+ ion chain, thereby sympathetically cooling the 9Be+ ions. Compared to previous implementations of conventional Raman sideband cooling, we achieve approximately an order-of-magnitude reduction in the duration required to cool the modes to near the ground state and significant reduction in required laser intensity. PMID:25167259

Lin, Y; Gaebler, J P; Tan, T R; Bowler, R; Jost, J D; Leibfried, D; Wineland, D J

2013-04-12

20

DETAILED STUDIES OF ELECTRON COOLING FRICTION FORCE.  

SciTech Connect

High-energy electron cooling for RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires detailed simulation of the electron cooling process. The first step towards such calculations is to have an accurate description of the cooling force. Numerical simulations are being used to explore various features of the friction force which appear due to several effects, including the anisotropy of the electron distribution in velocity space and the effect of a strong solenoidal magnetic field. These aspects are being studied in detail using the VORFAL code, which explicitly resolves close binary collisions. Results are compared with available asymptotic and empirical formulas and also, using the BETACOOL code, with direct numerical integration of less approximate expressions over the specified electron distribution function.

FEDOTOV, A.V.; BRUHWILER, D.L.; ABELL, D.T.; SIDORIN, A.O.

2005-09-18

21

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

22

HIRFL-CSR electron cooling devices  

NASA Astrophysics Data System (ADS)

Electron cooling devices for HIRFL-CSR were under construction through collaboration between BINP and IMP [1]. The main parameters, design points and progress of the cooler devices will be presented. The electron motions in the gun region, adiabatic expansion region, toroid region and collector region were simulated with the help of numerical calculation. Cooling times of the typical heavy ions with injection energy were calculated with aid of the code. The prototypes of solenoid coils at the cooling section were fabricated and measured, the results show that the transverse components of the magnetic field for single coil is less than 2×10-4.

Yang, X. D.; Zhao, H. W.; Xia, J. W.; Zhan, W. L.; Wei, B. W.; Parkhomchuk, V. V.

2001-12-01

23

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

24

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

25

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

26

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

27

Electron Beam Size Measurements in the Fermilab Electron Cooling System  

NASA Astrophysics Data System (ADS)

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements.

Kroc, T. K.; Burov, A. V.; Bolshakov, T. B.; Shemyakin, A.; Seletskiy, S. M.

2006-03-01

28

Electron beam size measurements in the Fermilab Electron Cooling System  

SciTech Connect

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements.

Kroc, T.K.; Burov, A.V.; Bolshakov, T.B.; Shemyakin, A.; /Fermilab; Seletskiy, S.M.; /Rochester U.

2005-09-01

29

Survey and Alignment of the Fermilab Electron Cooling System  

SciTech Connect

The goal of achieving the Tevatron luminosity of 3 x 10{sup 32} cm{sup -2}s{sup -1} requires Electron Cooling in the Recycler Ring to provide an increased flux of antiprotons. The Fermilab Electron Cooling system has been designed to assist accumulation of antiprotons for the Tevatron collider operations. The installation along with the survey and alignment of the Electron Cooling system in the Recycler Ring were completed in November 2004. The Electron Cooling system was fully commissioned in May 2005 and the first cooling of antiprotons was achieved in July 2005. This paper discusses the alignment methodology employed to survey and align the Electron Cooling system.

Oshinowo, Babatunde O'Sheg; Leibfritz, Jerry

2006-09-01

30

Evaluation of Cooling Solutions for Outdoor Electronics  

E-print Network

The thermal management of an outdoor electronic enclosure can be quite challenging due to the additional thermal load from the sun and the requirement of having an air-sealed enclosure. It is essential to consider the effect of solar heating loads in the design process; otherwise, it can shorten the life expectancy of the electronic product or lead to catastrophic failure. In this paper we analyze and compare the effectiveness of different cooling techniques used for outdoor electronics. Various cooling techniques were compared like special coatings and paints on the outer surface, radiation shields, double-walled vented enclosures, fans for internal air circulation and air-to-air heat exchangers. A highly simplified, typical outdoor system was selected for this study measuring approximately 300x300x400 mm (WxLxH). Solar radiation was incident on 3 sides of the enclosure. There were 8 equally spaced PCBs inside the enclosure dissipating 12.5W each uniformly (100 watts total). A computational fluid dynamics (CFD) model of the system was built and analyzed. This was followed by building a mock-up of the system and conducting experiments to validate the CFD model. It was found that some of the simplest cooling techniques like white oil paint on the outer surface can significantly reduce the impact of solar loads. Adding internal circulation fans can also be very effective. Using air-to-air heat exchangers was found to be the most effective solution although it is more complex and costly.

Mahendra Wankhede; V. Khaire; A. Goswami; S. D. Mahajan

2008-01-07

31

Cooling an electron gas using quantum dot based electronic refrigeration  

E-print Network

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... of refrigerator is best suited to be used in conjunction with a dilution fridge or Helium-3 system to provide a final stage of cooling. The scheme was first investigated theoretically in 1993 by Edwards et al. but, to our knowledge, has never before been...

Prance, Jonathan Robert

2009-10-13

32

Emerging Two-Phase Cooling Technologies for Power Electronic Inverters  

Microsoft Academic Search

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

2005-01-01

33

Decoherence of electron beams by electromagnetic field fluctuations  

Microsoft Academic Search

Electromagnetic field fluctuations are responsible for the destruction of electron coherence (dephasing) in solids and in vacuum electron beam interference. The vacuum fluctuations are modified by conductors and dielectrics, as in the Casimir effect, and hence, bodies in the vicinity of the beams can influence the beam coherence. We calculate the quenching of interference of two beams moving in vacuum

Yehoshua Levinson

2004-01-01

34

Study of the electromagnetic fields in an electron RFQ structure  

Microsoft Academic Search

The increasing interest in high brightness electron injectors, especially with regard to FEL applications, stimulated us to study the feasibility of RFQ for electrons. In this paper, the correct electromagnetic fields are derived for a structure where it is no longer possible to use the T-K electrostatic approximation because the beam aperture is not much smaller than the wavelength.

L. Picardi; P. Raimondi; C. Ronsivalle

1991-01-01

35

BPM System for Electron Cooling in the Fermilab Recycler Ring  

NASA Astrophysics Data System (ADS)

We report a VXI based system used to acquire and process BPM data for the electron cooling system in the Fermilab Recycler ring. The BPM system supports acquisition of data from 19 BPM locations in five different sections of the electron cooling apparatus. Beam positions for both electrons and anti-protons can be detected simultaneously with a resolution of ±50 ?m. We calibrate the system independently for each beam type at each BPM location. We describe the system components, signal processing and modes of operation used in support of the electron-cooling project and present experimental results of system performance for the developmental electron cooling installation at Fermilab.

Joireman, Paul W.; Cai, Jerry; Chase, Brian E.; Saewert, Greg W.

2004-11-01

36

Microbunched electron cooling for high-energy hadron beams.  

PubMed

Electron and stochastic cooling are proven methods for cooling low-energy hadron beams, but at present there is no way of cooling hadrons as they near the TeV scale. In the 1980s, Derbenev suggested that electron instabilities, such as free-electron lasers, could create collective space charge fields strong enough to correct the hadron energies. This Letter presents a variation on Derbenev's electron cooling scheme using the microbunching instability as the amplifier. The large bandwidth of the instability allows for faster cooling of high-density beams. A simple analytical model illustrates the cooling mechanism, and simulations show cooling rates for realistic parameters of the Large Hadron Collider. PMID:24010445

Ratner, D

2013-08-23

37

ELECTRON COOLING AND ELECTRON-ION COLLIDERS AT BNL.  

SciTech Connect

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

BEN-ZVI,I.

2007-10-03

38

Electron Cooling of Highly Charged Ions in Penning Traps  

SciTech Connect

For recent and planned experiments like the CPT-tests with antihydrogen at CERN (ATHENA, ATRAP) or the QED-tests and various other investigations with slow highly charged ions at GSI (HTTRAP), the ions or antiprotons are cooled with electrons or positrons in Penning traps. In many of these applications an efficient and fast cooling is crucial. In particular for electron cooling of highly charged ions, like e.g. of U92+ in HITRAP, sufficiently large cooling rates are mandatory for avoiding too much losses by recombination or charge exchange processes. Here we present calculations of electron cooling and recombination losses of an ensemble of ions in a Penning traps based on a detailed description of the cooling force and the actual radiative ion-electron recombination rate. We focus on the cooling of highly charged ions, namely bare Uranium, in HITRAP. Both the associated cooling times and recombination losses strongly depend on the density of the electrons and the ratio of the number of ions to the number of electrons in the trap. Our analysis shows that electron cooling of bare Uranium with an initial energy of a few keV/u is feasible with a cooling time less than about a second at less than 10 percent recombination losses.

Zwicknagel, Guenter [Institut fuer Theoretische Physik, Universitaet Erlangen-Nuernberg, Staudtstr. 7, D - 91058 Erlangen (Germany)

2006-10-18

39

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.

40

Qubit logic modeling by electronic circuits and electromagnetic signals  

E-print Network

In the paper an approach is presented allowing to model quantum logic circuits by electronic gates for discrete spatially modulated electromagnetic signals. The designed circuitry is for modeling low scale quantum nets of general design and quantum devices based only on superposition principle of their work.

G. A. Kouzaev

2001-08-02

41

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

42

Electromagnetic solitary pulses in a magnetized electron-positron plasma.  

PubMed

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 Alfvén speed. They can be associated with localized electromagnetic field excitations in magnetized laboratory and space plasmas composed of electrons and positrons. PMID:22060541

Shukla, P K; Eliasson, B; Stenflo, L

2011-09-01

43

Free-electron lasers with electromagnetic standing wave wigglers  

Microsoft Academic Search

A detailed analysis of the electromagnetic standing wave wiggler for free-electron lasers (FEL's) is conducted for both circular and linear wiggler polarizations, following a single-particle approach. After determination of the unperturbed electron orbits in the wiggler field, the single-particle spontaneous emission spectrum and subsequently the gain in the low gain Compton regime (using the Einstein coefficient method) are explicitly calculated.

T. M. TRAN; BRUCE G. DANLY; J. S. Wurtele

1987-01-01

44

Relativistic electromagnetic waves in an electron-ion plasma  

NASA Technical Reports Server (NTRS)

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.

1987-01-01

45

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

46

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

47

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

E-print Network

Classical ``Dressing'' of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald Joseph densities of the fields of a free electron in a plane electromagnetic wave include interference terms of a free electron in a electromagnetic wave is one of the most commonly discussed topics in classical

McDonald, Kirk

48

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

E-print Network

Classical "Dressing" of a Free Electron in a Plane Electromagnetic Wave Kirk T. McDonald Joseph densities of the fields of a free electron in a plane electromagnetic wave include interference terms of a free electron in a electromagnetic wave is one of the most commonly discussed topics in classical

McDonald, Kirk

49

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

50

Efficient cooling with tool inserts manufactured by electron beam melting  

Microsoft Academic Search

Purpose – The purpose of this paper is to present a comparative study, regarding cooling time and dimensional accuracy, of conventional injection mold cooling channel layouts, using straight holes and a baffle, and free-form fabricated (FFF) layout, manufactured by the direct-metal rapid tooling (RT) method electron beam melting (EBM). Many other methods have been proven useful for RT, but the

L. E. Rännar; A. Glad; C. G. Gustafson

2007-01-01

51

PERFORMANCE TEST AT THE SIS ELECTRON COOLING DEVICE  

Microsoft Academic Search

The new electron cooling device for the heavy ion syn- chrotron SIS was operated at a test bench before integration in the accelerator. The results of performance tests will be reported. Prior to the tests the magnetic field in the cooling section was mapped and optimized with respect to angular fluctuations. They could be reduced to less than 0.04 mrad.

L. Groening; M. Steck; T. Winkler; Germany V. I. Kudelainen; V. V. Parkhomchuk; A. I. Sharapa; A. V. Shemyakin; B. M. Smirnov

52

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

53

Cooling of cryogenic electron bilayers via the Coulomb interaction  

E-print Network

Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

John King Gamble; Mark Friesen; Robert Joynt; S. N. Coppersmith

2011-04-13

54

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

55

Electromagnetic and thermal models of emission of a cooled directional for local endocavity hyperthermia  

NASA Astrophysics Data System (ADS)

Possibilities of creation of controlled temperature fields in deep-seated biological tissue with the use of a microwave endocavity applicator with directed emission and surface cooling are explored. Mathematical models are proposed and calculated that make it possible to construct electromagnetic and thermal fields in biotissue depending on the specific thermophysical and ultrasound characteristics of the medium being irradiated, and to reveal situations and effects which should be achieved to solve problems of practical medicine in the field of local microwave hyperthermia of tissues.

Volkov, B. V.; Sigal, V. L.; Panteleev, A. D.; Sidoruk, Yu. K.

1996-09-01

56

Feasibility of electron cooling and luminosity potentials of colliders  

SciTech Connect

Luminosity upgrades of colliders with hadron beams tend to require decreased and maintained beam emittances using a suitable cooling technique. The breakthroughs of recent years: realization of beam energy recovery in superconducting linear accelerators; flat to round beam transformations; and new beam transport concepts (discontinuous solenoid, circulator rings, hollow beams, dispersive cooling); have promoted the feasibility of efficient electron cooling of intense high energy hadron beams. Electron cooling, in cooperation with strong SRF fields in storage rings, will allow one to obtain very short hadron bunches, as result of which the luminosity can be raised by making a low beta-star. Short bunches also would make feasible crab crossing, that allows one to remove the parasitic beam-beam interactions and maximize the collision rate. Cooling also results in flatness of uncoupled beam equilibrium; this can be used to diminish the IBS impact on luminosity.

Yaroslav Derbenev

2004-07-02

57

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

SciTech Connect

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

Nelson, S.D.; Reitter, T.; Caplan, M. [and others

1995-05-12

58

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

59

Installation and Commissioning of the On-Detector Electronics for the CMS Electromagnetic Crystal Calorimeter  

E-print Network

The CMS electromagnetic barrel calorimeter is composed of 76,000 PbWO4 scintillating crystals. The scintillating light is captured by photodiodes, amplified and digitized. The conversion is performed inside the detector volume and data are transported through optical fibers to the off-detector electronics. About 25,000 Printed Circuit Boards of 5 different types and 5,500 Gigabit-Optical-Links and fibers should be installed and tested. The integration of electronics, cooling system, mechanical supports, low and high voltage distribution, synchronization and controls are discussed. Each step of the assembly sequence is followed by extensive test and quality control. Installation, commissioning strategy and the achieved system performance results are presented.

Biino, Cristina

2007-01-01

60

Two-phase cooling method using R134a refrigerant to cool power electronic devices  

Microsoft Academic Search

This paper presents a two-phase cooling method using R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PE) such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles (HEVs). The cooling method involves submerging PE devices in an R134a bath, which limits the junction temperature of PE devices while conserving weight

Jeremy B. Campbell; Leon M. Tolbert; Curt W. Ayers; Burak Ozpineci

2005-01-01

61

Properties of electrons scattered on a strong plane electromagnetic wave with a linear polarization: classical treatment  

E-print Network

The relations among the components of the exit momenta of ultrarelativistic electrons scattered on a strong electromagnetic wave of a low (optical) frequency and linear polarization are established using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum components of the electrons traversed the electromagnetic wave depend weakly on the initial values of the momenta. These electrons are mostly scattered at the small angles to the direction of propagation of the electromagnetic wave. The maximum Lorentz factor of the electrons crossed the electromagnetic wave is proportional to the work done by the electromagnetic field and is independent of the initial momenta. The momentum component parallel to the electric field strength vector of the electromagnetic wave is determined only by the diameter of the laser beam measured in the units of the classical electron radius. As for the reflected electrons, they for the most part l...

Bogdanov, O V

2014-01-01

62

Electron beam size measurements in a cooling solenoid  

SciTech Connect

The Fermilab Electron Cooling Project [1] requires a straight trajectory and constant beam size to provide effective cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper discusses the required beam parameters, the implementation of the measurement system and results for our application.

Kroc, T.K.; Burov, A.V.; Bolshakov, T.B.; Shemyakin, A.; /Fermilab; Seletskiy, S.M.; /Rochester U.

2005-05-01

63

Optimization of electron cooling by SIN tunnel junctions  

NASA Astrophysics Data System (ADS)

We report on the optimization of electron cooling by SIN tunnel junctions due to the advanced geometry of superconducting electrodes and very effective normal metal traps for more efficient removal of quasiparticles at temperatures from 25 to 500 mK. The maximum decrease in electron temperature of about 200 mK has been observed at bath temperatures 300-350 mK. We used four-junction geometry with Al-AlOx-Cr/Cu tunnel junctions and Au traps. Efficient electron cooling was realized due to the improved geometry of the cooling tunnel junctions (quadrant shape of the superconducting electrode) and optimized Au traps just near the junctions ({\\approx }0.5~\\micmu {\\mathrm {m}} ) to reduce reabsorption of quasiparticles after removing them from normal metal. The maximum cooling effect was increased from a temperature drop of d T = -56 mK (ordinary cross geometry) to -130 mK (improved geometry of superconducting electrodes) and to d T = -200 mK (improved geometry of superconducting electrodes and effective Au traps). The heating peak (instead of cooling) near the zero voltage across cooling junctions has been observed in practice for all samples at temperatures below 150 mK. For higher cooling voltages close to the superconducting gap, the heating was converted to cooling with decreased amplitude. The leakage resistance of the tunnel junctions gives a reasonable explanation of the heating peak. The phonon reabsorption due to the recombination of quasiparticles in superconducting electrodes gives an additional improvement in the theoretical fitting but could not explain the heating peak. An anomalous zero-bias resistance peak has been observed for all tested structures. The peak is explained by Coulomb blockade of tunnelling in transistor-type structures with relatively small tunnel junctions. The work on electron cooling is devoted to the development of a cold-electron bolometer (CEB) with capacitive coupling by SIN tunnel junctions to the antenna for sensitive detection in the terahertz region. Direct electron cooling of an absorber plays a crucial role in supersensitive detection in the presence of a realistic background power load.

Kuzmin, L.; Agulo, I.; Fominsky, M.; Savin, A.; Tarasov, M.

2004-05-01

64

Ultrarelativistic electron states in a general background electromagnetic field.  

PubMed

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 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. PMID:25105600

Di Piazza, A

2014-07-25

65

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

PubMed

Electromagnetic field (EMF) treatment is presented as an alternative physical treatment for the mitigation of biofouling adhered to the tubes of a heat exchanger-condenser cooled by seawater. During an experimental phase, a fouling biofilm was allowed to grow until experimental variables indicated that its growth had stabilised. Subsequently, EMF treatment was applied to seawater to eliminate the biofilm and to maintain the achieved cleanliness. The results showed that EMFs precipitated ions dissolved in the seawater. As a consequence of the application of EMFs, erosion altered the intermolecular bonding of extracellular polymers, causing the destruction of the biofilm matrix and its detachment from the inner surface of the heat exchanger-condenser tubes. This detachment led to the partial removal of a mature biofilm and a partial recovery of the efficiency lost in the heat transfer process by using a physical treatment that is harmless to the marine environment. PMID:24266611

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

2014-01-01

66

Electron Cooling in a Young Radio Supernova: SN 2012aw  

NASA Astrophysics Data System (ADS)

We present the radio observations and modeling of an optically bright Type II-P supernova (SN), SN 2012aw which exploded in the nearby galaxy Messier 95 (M95) at a distance of 10 Mpc. The spectral index values calculated using C, X, and K bands are smaller than the expected values for the optically thin regime. During this time, the optical bolometric light curve stays in the plateau phase. We interpret the low spectral-index values to be a result of electron cooling. On the basis of comparison between the Compton cooling timescale and the synchrotron cooling timescale, we find that the inverse Compton cooling process dominates over the synchrotron cooling process. We therefore model the radio emission as synchrotron emission from a relativistic electron population with a high energy cutoff. The cutoff is determined by comparing the electron cooling timescale, t cool, and the acceleration timescale, \\tilde{t}_{acc}. We constrain the mass-loss rate in the wind (\\dot{M}\\sim 1.9\\times 10^{-6}\\ M_{\\odot }\\,yr^{-1}) and the equipartition factor between relativistic electrons and the magnetic field (\\tilde{\\alpha }=\\epsilon _e/\\epsilon _B\\sim 1.12\\times 10^2) through our modeling of radio emission. Although the time of explosion is fairly well constrained by optical observations within about two days, we explore the effect of varying the time of explosion to best fit the radio light curves. The best fit is obtained for the explosion date as 2012 March 15.3 UT.

Yadav, Naveen; Ray, Alak; Chakraborti, Sayan; Stockdale, Christopher; Chandra, Poonam; Smith, Randall; Roy, Rupak; Bose, Subhash; Dwarkadas, Vikram; Sutaria, Firoza; Pooley, David

2014-02-01

67

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

68

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

69

Electron cooling in decaying low-pressure plasmas  

NASA Astrophysics Data System (ADS)

A simple analytical fluid dynamic model is developed for evaporative electron cooling in a low-pressure decaying plasma and compared to a two-dimensional simulation and experimental data for the particular case of argon. Measured electron temperature and density developments are fully reproduced by the ab initio model and the simulation. Further, it is shown that in the late afterglow thermalization of electrons occurs by coupling to the ion fluid via Coulomb collisions at sufficiently high electron densities and not by coupling to the neutral background.

Celik, Yusuf; Tsankov, Tsanko V.; Aramaki, Mitsutoshi; Yoshimura, Shinji; Luggenhölscher, Dirk; Czarnetzki, Uwe

2012-04-01

70

High density electronic packaging module with improved cooling assembly  

NASA Technical Reports Server (NTRS)

Cold plate increases heat transfer within high density electronic module. Tapered pins improve heat transfer process by providing larger surface pressure with increased planar area. Cooling technique increases thermal contact where planar area is limited, interface pressure increases the heat transfer coefficient.

Martin, J. H.

1971-01-01

71

Electromagnetic effects of neutrinos in an electron gas  

SciTech Connect

We study the electromagnetic properties of a system that consists of an electron background and a neutrino gas that may be moving or at rest, as a whole, relative to the background. The photon self-energy for this system is characterized by the usual transverse and longitudinal polarization functions, and two additional ones which are the focus of our calculations, that give rise to birefringence and anisotropic effects in the photon dispersion relations. Expressions for them are obtained, which depend on the neutrino number densities and involve momentum integrals over the electron distribution functions, and are valid for any value of the photon momentum and general conditions of the electron gas. Those expressions are evaluated explicitly for several special cases and approximations which are generally useful in astrophysical and cosmological settings. Besides studying the photon dispersion relations, we consider the macroscopic electrodynamic equations for this system, which involve the standard dielectric and permeability constants plus two additional ones related to the photon self-energy functions. As an illustration, the equations are used to discuss the evolution of a magnetic field perturbation in such a medium. This particular phenomena has also been considered in a recent work by Semikoz and Sokoloff as a mechanism for the generation of large-scale magnetic fields in the early Universe as a consequence of the neutrino-plasma interactions, and allows us to establish contact with a specific application in a well defined context, with a broader scope and from a very different point of view.

Nieves, Jose F.; Sahu, Sarira [Laboratory of Theoretical Physics, Department of Physics, P.O. Box 23343, University of Puerto Rico Rio Piedras, 00931-3343 (Puerto Rico); Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, C. U., A. Postal 70-543, 04510 Mexico DF (Mexico)

2005-04-01

72

Electromagnetic Waves and Bursty Electron Acceleration: Implications from Freja  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

73

Electromagnetic and electrostatic emissions from a thin electron beam in space plasma  

NASA Astrophysics Data System (ADS)

Electromagnetic and electrostatic emissions from a spatially confined thin electron beam in a space plasma is studied via electromagnetic particle simulations. We assumed a top-hat ion density model to compensate an excess charge induced by an electron beam injection to identify an effect of current injection from a charge injection effect. At the onset of an electron beam injection, impulsive electromagnetic waves are radiated, propagating away from the electron beam. The simulation system is a two-dimensional x-y plane with both a static magnetic field and an electron beam drift in the y-direction. Boundary conditions are open in the x-direction and periodic in the y-direction. The electromagnetic waves can propagate without reflection at the x-boundaries where a masking method is used to absorb outgoing waves. An instability similar to the conventional two-stream instability in a uniform beam-plasma system develops after the initial response, and beam electrons are diffused. During this quasi-steady period, both electromagnetic and electrostatic waves are excited through the Landau resonance with beam electrons. Electrostatic emissions are confined to a region close to the electron beam, while the electromagnetic emissions propagate away from the beam depending on wave normal angles relative to a static magnetic field. Spatial configuration of the electromagnetic wave spectra shows a close resemblance to a funnel shaped VLF emissions observed in the Spacelab-2 electron beam experiment.

Omura, Yoshiharu; Matsumoto, Hiroshi

1988-04-01

74

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

SciTech Connect

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

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

2007-01-01

75

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

76

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

77

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.

78

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). In order to create a large ...

Kwon, Daniel W., 1980-

2009-01-01

79

Weak and electromagnetic mechanisms of neutrino-pair photoproduction in a strongly magnetized electron gas  

SciTech Connect

Expressions for the power of neutrino radiation from a degenerate electron gas in a strong magnetic field are derived for the case of neutrino-pair photoproduction via the weak and electromagnetic interaction mechanisms (it is assumed that the neutrino possesses electromagnetic form factors). It is shown that the neutrino luminosity of a medium in the electromagnetic reaction channel may exceed substantially the luminosity in the weak channel. Relative upper bounds on the effective neutrino magnetic moment are obtained.

Borisov, A. V.; Kerimov, B. K.; Sizin, P. E., E-mail: borisov@phys.msu.ru [Moscow State University (Russian Federation)

2012-11-15

80

Principles of gyrotron powered electromagnetic wigglers for free-electron lasers  

Microsoft Academic Search

The operation of free-electron lasers (FEL's) with axial electron beams and high-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 cavities can significantly reduce required electron beam voltages, resulting in compact FEL's. Gain calculations in the low- and high-gain Compton regime are presented, including the

B. G. Danly; G. Bekefi; R. C. Davidson; R. J. Temkin; T. M. Tran; J. S. Wurtele

1987-01-01

81

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

82

Detecting and locating electronic devices using their unintended electromagnetic emissions  

NASA Astrophysics Data System (ADS)

Electronically-initiated explosives can have unintended electromagnetic emissions which propagate through walls and sealed containers. These emissions, if properly characterized, enable the prompt and accurate detection of explosive threats. The following dissertation develops and evaluates techniques for detecting and locating common electronic initiators. The unintended emissions of radio receivers and microcontrollers are analyzed. These emissions are low-power radio signals that result from the device's normal operation. In the first section, it is demonstrated that arbitrary signals can be injected into a radio receiver's unintended emissions using a relatively weak stimulation signal. This effect is called stimulated emissions. The performance of stimulated emissions is compared to passive detection techniques. The novel technique offers a 5 to 10 dB sensitivity improvement over passive methods for detecting radio receivers. The second section develops a radar-like technique for accurately locating radio receivers. The radar utilizes the stimulated emissions technique with wideband signals. A radar-like system is designed and implemented in hardware. Its accuracy tested in a noisy, multipath-rich, indoor environment. The proposed radar can locate superheterodyne radio receivers with a root mean square position error less than 5 meters when the SNR is 15 dB or above. In the third section, an analytic model is developed for the unintended emissions of microcontrollers. It is demonstrated that these emissions consist of a periodic train of impulses. Measurements of an 8051 microcontroller validate this model. The model is used to evaluate the noise performance of several existing algorithms. Results indicate that the pitch estimation techniques have a 4 dB sensitivity improvement over epoch folding algorithms.

Stagner, Colin Blake

83

Stimulated Raman up-conversion of electromagnetic waves by a gyrating electron beam  

NASA Technical Reports Server (NTRS)

A gyrating electron beam supports negative energy modes near the harmonics of electron-cyclotron frequency. An electromagnetic wave passing through such a beam parametrically up-converts into high-frequency electromagnetic modes separated from the pump frequency by the electron-cyclotron harmonics. The growth rate for this process varies directly as the oscillatory velocity of beam electrons caused by the pump and as square root of the beam density. It has a maximum at values of scattering angle close to 180 deg and is also implicitly dependent on the beam veocity and the cyclotron frequency of electrons. The effect of a cold electron component is to reduce the growth rate.

Sharma, O. P.; Patel, V. L.

1983-01-01

84

Energy conversion between electrons and phonons in heterostructures for thermionic cooling  

SciTech Connect

The energy conversion between electrons and phonons in a heterostructure is studied for thermionic cooling by using the hot electron approximation. Calculations show that the energy exchange rate between electrons and phonons should be small for a net cooling power, and the film thickness should be in the range of micron for effective cooling.

Zeng, T.; Chen, G.

1999-07-01

85

Luminosity of the NICA Collider in working mode with using electron cooling system  

NASA Astrophysics Data System (ADS)

The paper investigates the problem of balance between the intrabeam scattering, electron cooling and radiative recombination processes in the NICA Collider working mode with using of electron cooling system. The reducing methods of radiative recombination influence due to electron cooling are discussed.

Kuznetsov, A. B.; Meshkov, I. N.; Tuzikov, A. V.; Philippov, A. V.

2014-09-01

86

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

87

Theory of atoms in strong, pulsed electromagnetic fields: 2, A free electron and a harmonically bound electron  

SciTech Connect

Multiple scale methods are used to treat several ingredients of the theory of atoms in strong electromagnetic fields. First, a focused electromagnetic field is expanded. Second, a classical electron is described giving the ponderomotive potential. Third, the quantum electron is treated in the WKB approximation. Fourth, the one dimensional quantum harmonic oscillator is solved; and last the one dimensional square well, showing the low intensity limit of the theory.

Szoeke, A.; Garrison, J.

1987-07-01

88

Competing channels for hot-electron cooling in graphene.  

PubMed

We report on temperature-dependent photocurrent measurements of high-quality dual-gated monolayer graphene p-n junction devices. A photothermoelectric effect governs the photocurrent response in our devices, allowing us to track the hot-electron temperature and probe hot-electron cooling channels over a wide temperature range (4 to 300 K). At high temperatures (T > T(*)), we found that both the peak photocurrent and the hot spot size decreased with temperature, while at low temperatures (T < T(*)), we found the opposite, namely that the peak photocurrent and the hot spot size increased with temperature. This nonmonotonic temperature dependence can be understood as resulting from the competition between two hot-electron cooling pathways: (a) (intrinsic) momentum-conserving normal collisions that dominates at low temperatures and (b) (extrinsic) disorder-assisted supercollisions that dominates at high temperatures. Gate control in our high-quality samples allows us to resolve the two processes in the same device for the first time. The peak temperature T(*) depends on carrier density and disorder concentration, thus allowing for an unprecedented way of controlling graphene's photoresponse. PMID:24996107

Ma, Qiong; Gabor, Nathaniel M; Andersen, Trond I; Nair, Nityan L; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

2014-06-20

89

Densities of Electron's Continuum in Gravitational and Electromagnetic Fields  

E-print Network

Relativistic dynamics of distributed mass and charge densities of the extended classical particle is discussed for arbitrary gravitational and electromagnetic fields. Vector geodesic relations for material space densities are consequences of tensor gravitational equations for continuous sources and their fields. Classical four-flows of elementary material space depend on local four-potentials for charged densities, like in quantum theory. Six electromagnetic intensities can describe satisfactorily only the simplest, potential kind of continuous matter motion.

I. E. Bulyzhenkov

2012-11-18

90

Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

91

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

92

Relativistic electron pitch-angle scattering by electromagnetic ion cyclotron waves during geomagnetic storms  

Microsoft Academic Search

During magnetic storms, relativistic electrons execute nearly circular orbits about the Earth and traverse a spatially confined zone within the duskside plasmapause where electromagnetic ion cyclotron (EMIC) waves are preferentially excited. We examine the mechanism of electron pitch-angle diffusion by gyroresonant interaction with EMIC waves as a cause of relativistic electron precipitation loss from the outer radiation belt. Detailed calculations

Danny Summers; Richard M. Thorne

2003-01-01

93

Production of flickering aurora and field-aligned electron flux by electromagnetic ion cyclotron waves  

Microsoft Academic Search

Recent observations have suggested that flickering aurora is produced by a modulation of the field-aligned component of the electron flux within an auroral arc. It is proposed that a portion of the field-aligned electrons are of ionospheric origin and that these electrons are accelerated and their flux modulated by electromagnetic ion cyclotron waves that occur below the main acceleration region

M. Temerin; J. McFadden; M. Boehm; C. W. Carlson; W. Lotko

1986-01-01

94

A New Principle for Electronic Cooling of Mesoscopic Systems  

NASA Astrophysics Data System (ADS)

In many semiconductor heterostructures the electrons behave like a low-dimensional system and develop new properties susceptible to control by an external parameter. Mesoscopic transport and optical properties have been studied extensively in this way, but low-dimensional thermal properties have to date received much less attention. In this work(Luis G.C. Rego and George Kirczenow, Appl. Phys. Lett. 75) (15), 2262 (99) we present the concepts of a new form of cooling of semiconductor mesoscopic samples which could be used in low temperature experiments. The cooling is the result of a quasi-static expansion of the electrons occupying the quasi-2D subbands of a quantum well (QW) or a multiple-quantum-well array, induced by an external electric field applied perpendicularly to the QW plane. Under ideal conditions the final temperature is half of the original and the dynamics of the process is universal and reversible. The feasibility of the process is investigated by self-consistent calculations at temperatures below 1K.

Rego, Luis G. C.

2000-03-01

95

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

96

Macroscopic descriptions of non-linear electromagnetic interactions in many-electron systems  

NASA Astrophysics Data System (ADS)

Reduced-density-matrix descriptions are developed for linear and non-linear (possibly coherent) electromagnetic interactions of many-electron systems. Applications of interest include pump-probe optical phenomena in warm atomic vapors, partially-ionized plasmas, and condensed matter. Collision processes are treated within the framework of environmental perturbations, giving rise to decoherence and relaxation phenomena, and externally applied magnetic fields are taken into account on an equal footing with the electromagnetic fields. Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified manner. The standard Born (lowest-order-perturbation) and Markov (short-memory-time) approximations are systematically introduced within the framework of the general non-perturbative and non-Markovian formulations. A preliminary semi-classical perturbation-theory treatment of the electromagnetic interaction is adopted. However, it is emphasized that a quantized-electromagnetic-field approach will be necessary for a fully self-consistent quantum-mechanical formulation. The primary quantities of interest are the linear and the non-linear macroscopic electromagnetic-response tensors. Coherent initial electronic excitations and the full tetradic-matrix form of the Liouville-space self-energy operator representing the environmental interactions in the Markov approximation can incorporated in the expressions for these macroscopic electromagnetic-response tensors. Collisional interactions can be treated in various approximations for the Liouville-space self-energy operator, and the influence of Zeeman coherences on the macroscopic electromagnetic response can be investigated.

Jacobs, Verne L.

2013-09-01

97

Electromagnetic pulse threats to electronic information system and corresponding protection measures  

Microsoft Academic Search

Electromagnetic pulse (EMP) radiation shall seriously disturb electronic information system. The EMP energy coupled from different approaches can even destroy semiconductor elements inside the equipment, make the system to function improperly. Several expressions of minatory EMP are investigated in this paper. The coupling characteristics and threat mechanism of EMP radiation entering into electronic information system are analyzed, and the EMP

Sheng-quan Zheng; Dong-yun Hou; Qi-feng Liu; Feng Deng

2011-01-01

98

The Screening Effect in Electromagnetic Production of Electron Positron Pairs in Relativistic Nucleus-Atom Collisions  

NASA Technical Reports Server (NTRS)

We study the screening effects of the atomic electrons in the electromagnetic production of electron-positron pairs in relativistic nucleus-atom collisions for fixed target experiments. Our results are contrasted with those obtained in bare collisions, with particular attention given to its dependence on the beam energy and the target atom.

Wu, Jianshi; Derrickson, J. H.; Parnell, T. A.; Strayer, M. R.

1999-01-01

99

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 a reduction in the size of power electronic systems and potentially reducing the overall costs of electric

100

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

101

IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 55, NO. 1, JANUARY 2008 245 Cool Chips: Opportunities and Implications for  

E-print Network

by global chip cooling and that localized cooling can be more effective in removing hot-spots. Index Terms--CoolingIEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 55, NO. 1, JANUARY 2008 245 Cool Chips: Opportunities cooling could be an effective knob for power and thermal man- agement. This paper analyzes IC cooling

102

Enhanced electromagnetic emission from plasmas containing positive dust grains and electrons  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

103

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

104

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

105

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

106

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

107

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

108

Electron trajectory and growth rate in a two-stream electromagnetically pumped free electron laser and axial guide field  

SciTech Connect

The effects of two-stream on electromagnetic wiggler free electron lasers (TSEMWFEL) with an axial guiding magnetic field are studied. An analysis of the two-stream steady-state electron trajectories is given by solving the equation of motion in the axial guiding magnetic field and the electromagnetic wiggler. Numerical calculations are made to illustrate the effects of the dual electron beam on the trajectories. The dispersion relation is derived employing linear fluid theory. The characteristics of the dispersion relation are analyzed numerically. The result shows that the growth rate is considerably enhanced in comparison with single-stream. The maximum growth rate is studied numerically as a function of axial guiding magnetic field for multiple electron trajectories. It is shown that the maximum growth rate of TSEMWFEL increases and decreases with respect to the axial guiding field for different trajectories.

Mehdian, H.; Saviz, S. [Department of Physics and Institute for Plasma Research, Tarbiat Moallem University, 49, Dr. Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

2008-09-15

109

Analytical method of electromagnetic susceptibility of electronic equipments with enclosure in electric power system at system level  

Microsoft Academic Search

With the development of the power system, protection for the electromagnetic interference is very important. Although protective measures of electronic equipment are improved. But the chassis itself shielded by the existence of defects (such as ventilation holes), leading to the shielding performance decline. In this paper the transmission line matrix method is applied to study electromagnetic signals couple in electronic

Ge Guo; Weidong Zhang; Xiang Cui; Rui Lin

2008-01-01

110

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

111

Numerical simulation of electromagnetic emissions in the solar wind plasma with non-thermal electron distribution  

NASA Astrophysics Data System (ADS)

Dynamics of fundamental and second harmonic electromagnetic emissions are simulated in the solar wind plasma in the presence of non-thermal electron distribution function in which primary Langmuir waves are driven by an electron beam. The electron velocity distribution function is separated into two distributions representing the distribution of the ambient electrons (Maxwellian) and the suprathermal electrons (non-thermal electrons). The effects of the non-thermal electrons on the generation of primary Langmuir waves, emission rates of the fundamental (F) and harmonic waves (H) and their distributions are investigated. The both of the F and H emissions are sensitive to the characterizes of the non-thermal electrons. It is found that in the presence of non-thermal electrons the production of the Langmuir waves decreases and consequently the levels of fundamental and second harmonic waves are reduced. The emission rate of the fundamental transverse waves decreases and its peak moves slightly toward smaller wave-numbers.

Khalilpour, H.

2014-09-01

112

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

113

Electromagnetic transient simulation of power electronic equipment in power systems: challenges and solutions  

Microsoft Academic Search

The panel presentation identities requirements for electromagnetic transient simulation programs for simulating large power networks with embedded power electronics. Interpolation based simulation and other methods are discussed which provide precision in simulation of semiconductor switching events without a corresponding penalty in computer time. A method for accurately estimating power semiconductor losses without significant increase in the simulation time is discussed.

A. M. Gole

2006-01-01

114

Sodium-immersed self-cooled electromagnetic pump design and development of a large-scale coil for high temperature  

SciTech Connect

A sodium-immersed, self-cooled electromagnetic (EM) pump was recently studied as a prospective innovative technology to simplify a fast breeder reactor plant system. The EM pump for a primary pump, a pump type, was designed, and the structural concept and the system performance were clarified. For the flow control method, a constant voltage/frequency method was preferable from the point of view of pump performance and efficiency. The insulation life was tested on a large-scale coil at high temperature as part of the development of a large-capacity EM pump. Mechanical and electrical damage were not observed, and the insulation performance was quite good. The insulation system could also be applied to large-scale coils.

Oto, Akihiro [Toshiba Corp., Yokohama (Japan); Naohara, Nobuyuki [Central Research Institute of Electric Power Industry, Tokyo (Japan); Ishida, Masayoshi [Central Research Institute of Electric Power Industry, Kanagawa (Japan). Yokosuka Research Laboratory; Kuroki, Toshitaka [Toshiba Corp., Yokohama (Japan); Katsuki, Kenji; Kumazawa, Ryouji [Toshiba Corp., Yokohama (Japan)

1995-05-01

115

Low frequency electromagnetic oscillations in dense degenerate electron-positron pair plasma, with and without ions  

SciTech Connect

Quantum plasma oscillations are studied in a strongly magnetized, ultra-dense plasma with degenerate electrons and positrons. The dispersive role of electron and positron quantum effects on low frequency (in comparison to electron cyclotron frequency) shear electromagnetic wave is investigated by employing hydrodynamic formulation. In the presence of ions, the density balance changes, and the electromagnetic wave (with frequency lower than the ion cyclotron frequency) is shown to couple with electrostatic ion mode under certain conditions. For such low frequency waves, it is also seen that the contribution of electron and positron degeneracy pressure is dominant as compared to their diffraction effects. The results are analyzed numerically for illustrative purpose pointing out their relevance to the dense laboratory (e.g., super-intense laser-dense matter interactions) and astrophysical plasmas.

Khan, S. A. [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad 45320 (Pakistan); Ayub, M. K. [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad 45320 (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Pohang University of Science and Technology (POSTECH), Pohang, Gyunbuk 790-784 (Korea, Republic of); Ahmad, Ali [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad 45320 (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology, Islamabad 44000 (Pakistan)

2012-10-15

116

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

SciTech Connect

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

Komar, A.; Pokol, G. I. [Department of Nuclear Techniques, Budapest University of Technology and Economics, Association EURATOM, H-1111 Budapest (Hungary); Fueloep, T. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden)

2013-01-15

117

Shadowing of the electromagnetic field of a relativistic electron  

Microsoft Academic Search

In coherent radiation sources (diffraction radiation, Smith-Purcell effect,\\u000aetc.) based on relativistic electrons passing by a material radiator, the\\u000aelectron self-field is partly shadowed after each part of the radiator over a\\u000adistance of the order of the formation length g2l. This effect has been\\u000ainvestigated on coherent diffraction radiation (DR) by electron bunches. An\\u000aabsorbing half-plane screen was placed

G. Naumenko; X. Artru; A. Potylitsyn; Yu. Popov; L. Sukhikh

2009-01-01

118

Experimental demonstration of an electromagnetically pumped free-electron laser with a cyclotron-harmonic idler  

Microsoft Academic Search

A three-wave, free-electron laser was operated with a powerful 8.4-GHz electromagnetic ''pump'' wave replacing the usual magnetostatic wiggler. The presence of a uniform axial magnetic field Bâ produced cyclotron-harmonic ''idler'' waves. Peaks in the emission spectrum corresponding to cyclotron harmonics were observed covering a frequency range from 16.5 to 130 GHz. The frequency spectrum of this novel free-electron laser mechanism

R. A. Kehs; Y. Carmel; V. L. Granatstein; W. W. Destler

1988-01-01

119

Superluminal spectral densities of ultra-relativistic electrons in intense electromagnetic wave fields  

Microsoft Academic Search

Superluminal radiation from electrons accelerated in electromagnetic waves is investigated. The radiation field is a Proca\\u000a field with negative mass-square, minimally coupled to the electron current. The spectrum is continuous in the ultra-relativistic\\u000a regime, where steepest-descent asymptotics can be used to evaluate the power coefficients. The time averaging of Lissajous\\u000a orbits in polarized wave fields is discussed, and the tachyonic

R. Tomaschitz

2010-01-01

120

Electromagnetically Induced Transparency with an Ensemble of Donor-Bound Electron Spins in a Semiconductor  

E-print Network

We present measurements of electromagnetically induced transparency with an ensemble of donor- bound electrons in low-doped n-GaAs. We used optical transitions from the Zeeman-split electron spin states to a bound trion state in samples with optical densities of 0.3 and 1.0. The electron spin dephasing time T* \\approx 2 ns was limited by hyperfine coupling to fluctuating nuclear spins. We also observe signatures of dynamical nuclear polarization, but find these effects to be much weaker than in experiments that use electron spin resonance and related experiments with quantum dots.

Sladkov, Maksym; Bakker, M P; Onur, A R; Reuter, D; Wieck, A D; van der Wal, C H

2010-01-01

121

Electromagnetically Induced Transparency with an Ensemble of Donor-Bound Electron Spins in a Semiconductor  

E-print Network

We present measurements of electromagnetically induced transparency with an ensemble of donor- bound electrons in low-doped n-GaAs. We used optical transitions from the Zeeman-split electron spin states to a bound trion state in samples with optical densities of 0.3 and 1.0. The electron spin dephasing time T* \\approx 2 ns was limited by hyperfine coupling to fluctuating nuclear spins. We also observe signatures of dynamical nuclear polarization, but find these effects to be much weaker than in experiments that use electron spin resonance and related experiments with quantum dots.

Maksym Sladkov; A. U. Chaubal; M. P. Bakker; A. R. Onur; D. Reuter; A. D. Wieck; C. H. van der Wal

2010-07-06

122

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

123

Steady-state electron trajectories and growth rate in electromagnetically pumped free-electron laser with specific nonuniform magnetic field  

SciTech Connect

A theory of the dispersion relation for electromagnetically pumped free-electron laser in the presence of a special tapered axial guide magnetic field is presented. An analysis of the steady-state electron trajectories is obtained by solving the equations of motion. Next an eleventh-degree polynomial equation for electromagnetic and space-charge wave is derived. Numerical solution of the polynomial equation of the dispersion relation yield the complex wave number as a function of the frequency of the waves. These results are used to illustrate the dependence of growth rate curves on the axial guide field frequency. It is found that the tapered guide field shifts electron trajectories and enhances the growth rate in the comparison of employing uniform axial magnetic field, without needing a strong guide magnetic field.

Mehdian, H.; Jafari, S.; Hasanbeigi, A. [Department of Physics and Institute for Plasma Research, Tarbiat Moallem University, Tehran 15614 (Iran, Islamic Republic of)

2008-07-15

124

Production of flickering aurora and field-aligned electron flux by electromagnetic ion cyclotron waves  

NASA Technical Reports Server (NTRS)

Recent observations have suggested that flickering aurora is produced by a modulation of the field-aligned component of the electron flux within an auroral arc. It is proposed that a portion of the field-aligned electrons are of ionospheric origin and that these electrons are accelerated and their flux modulated by electromagnetic ion cyclotron waves that occur below the main acceleration region on auroral arc field lines. A model of the electromagnetic ion cyclotron wave shows that the parallel phase velocity of the wave increase as the wave propagates toward the ionosphere. A test particle calculation shows that ionospheric electrons trapped or reflected by the wave are accelerated to energies of several keV and that their flux is modulated at the wave frequency. The relative amplitudes of the model wave electric fields are consistent with the observations of small-scale low-frequency ionospheric and magnetospheric electric fields near auroral arcs of approximately 10 mV/m and 100 mV/m, respectively. The large-amplitude ion cyclotron waves also produce a ponderomotive force and a self-consistent ambipolar electric field. Energy considerations show that the downward energy flux in the electromagnetic ion cyclotron wave can be several percent of the total downward auroral electron energy flux.

Temerin, M.; Mcfadden, J.; Boehm, M.; Carlson, C. W.; Lotko, W.

1986-01-01

125

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

126

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

SciTech Connect

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

Zacharias, Michael; Schlickeiser, Reinhard, E-mail: mz@tp4.rub.de, E-mail: rsch@tp4.rub.de [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2012-12-20

127

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

128

A Unique Approach to Power Electronics and Motor Cooling in a Hybrid Electric Vehicle Environment  

SciTech Connect

An innovative system for cooling the power electronics of hybrid electric vehicles is presented. This system uses a typical automotive refrigerant R-134a (1,1,1,2 tetrafluoroethane) as the cooling fluid in a system that can be used as either part of the existing vehicle passenger air conditioning system or separately and independently of the existing air conditioner. Because of the design characteristics, the cooling coefficient of performance is on the order of 40. Because liquid refrigerant is used to cool the electronics directly, high heat fluxes can result while maintaining an electronics junction temperature at an acceptable value. In addition, an inverter housing that occupies only half the volume of a conventional inverter has been designed to take advantage of this cooling system. Planned improvements should result in further volume reductions while maintaining a high power level.

Ayers, Curtis William [ORNL; Hsu, John S [ORNL; Lowe, Kirk T [ORNL; Conklin, Jim [ORNL

2007-01-01

129

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

130

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 Abstract-The operation of free-electron lasers (FEL's) with axial electron beams and high-powerIEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-23, NO. 1, JANUARY 1987 103 Principles of Gyrotron

Wurtele, Jonathan

131

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

132

Cooling problems and thermal issues in high power electronics - a multi faceted design approach  

Microsoft Academic Search

This paper provides a review of some of the issues currently facing thermal designers of high power electronics. With the current market resistance to widely embrace advanced methods such as liquid cooling, air cooling will continue to be a popular choice (K. Azar, 8th THERMINIC workshop, 2002). As heat loads increase and system sizes reduce, further innovation and optimisation of

Masud Behnia; Luke Maguire; Graham Morrison

2004-01-01

133

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,

134

The Use of vapor chambers and heat pipes for cooling military embedded electronic devices  

Microsoft Academic Search

Increasing computing power in military embedded electronics require innovative thermal solutions to meet the rugged environments at which they are expected to perform. One of the major challenges in cooling these devices is the conduction resistance associated with transporting the dissipated power from a PCB through aluminum and copper to the external cooling locations (liquid, forced convection, or natural convection).

Matthew J. Connors; John A. Zunner

2009-01-01

135

Equations of motion for a free-electron laser with an electromagnetic pump field and an axial electrostatic field  

NASA Technical Reports Server (NTRS)

The equations of motion for a free-electron laser (FEL) with an electromagnetic pump field and a static axial electric field are derived using a Hamiltonian formalism. Equations governing the energy transfer between the electron beam and each of the electromagnetic fields are given, and the phase shift for each of the electromagnetic fields is derived from a linearized Maxwell wave equation. The relation between the static axial electric field and the resonant phase is given. Laser gain and the fraction of the electron energy converted to photon energy are determined using a simplified resonant particle model. These results are compared to those of a more exact particle simulation code.

Hiddleston, H. R.; Segall, S. B.

1981-01-01

136

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

137

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

138

Investigation of the surface current excitation by a relativistic electron electromagnetic field  

NASA Astrophysics Data System (ADS)

Surface current method and pseudo-photon ones are widely used in the problems of diffraction and transition radiation of relativistic electron in conductive targets. The simple analysis disclosed the contradiction between these methods in respect to the surface current excitation on target surfaces. This contradiction was resolved experimentally by the measurement of a surface current on the upstream and downstream target surfaces in diffraction radiation geometry. The experimental test showed, that no surface current is induced on the target downstream surface under the influence of a relativistic electron electromagnetic field in contrast to the upstream surface. This is important for the understanding of a forward transition and diffraction radiation nature and electromagnetic field evolution in interaction processes.

Naumenko, G.; Potylitsyn, A.; Popov, Yu; Sukhikh, L.; Shevelev, M.

2010-06-01

139

Electromagnetic levitation facility incorporating electron beam. [for vacuum heating and melting  

NASA Technical Reports Server (NTRS)

An electromagnetic levitation apparatus incorporating an electron beam for auxiliary heating and melting has been developed for experiments on containerless vacuum purification and undercooled solidification of high melting materials. Stable levitation of 10-g specimens of molten tungsten has been achieved and a variety of containerless solidification experiments is being performed, including pure polycrystalline castings and single tungsten crystals grown from the undercooled levitated melts.

Wouch, G.; Okress, E. C.; Frost, R. T.; Rutecki, D. J.

1975-01-01

140

A long electromagnetic wiggler for the PALADIN free-electron laser experiments  

Microsoft Academic Search

The authors have designed, built, and tested a 25.6-m-long wiggler for a free-electron-laser (FEL) experiment. It is a DC iron-core electromagnetic wiggler that incorporates a number of important and unique facilities. Permanent magnets are used to suppress saturation in the iron and extend the linear operating range. Steering-free excitation allows real-time adjustment of the field taper without causing beam steering.

G. A. Deis; A. R. Harvey; C. D. Parkison; D. Prosnitz; J. Rego; E. T. Scharlemann; K. Halbach

1988-01-01

141

Radiational self-polarization of electrons moving in the electromagnetic plane-wave field  

Microsoft Academic Search

Summary  The radiational self-polarization effect induced by spontaneous radiation is shown to be possible for an electron moving in\\u000a the electromagnetic plane-wave field. It is quite similar to the well-known Sokolov-Ternov effect, as regards the synchrotron\\u000a radiation. The physical analysis of the self-polarization process is given and qualitative estimates for experimental observation\\u000a of the predicted effect are discussed.

V. G. Bagrov; N. I. Fedosov; G. F. Kopytov; S. S. Oxsyzyan; V. B. Tlyachev

1989-01-01

142

Oblique electromagnetic instabilities for an ultra relativistic electron beam passing through a plasma  

E-print Network

We present an investigation of the electromagnetic instabilities which are trig gered when an ultra relativistic electron beam passes through a plasma. The linear growth rate is computed for every direction of propagation of the unstable modes, and temperatures are modelled using simple waterbag distribution functions. The ultra relativistic unstable spectrum is located around a very narrow band centered on a critical angle which value is given analytically. The growth rate of modes propagating in this direction decreases like k^(-1/3).

A. Bret

2006-04-07

143

Electron-positron pair production by electromagnetic pulses  

SciTech Connect

Electron-positron pair production in vacuum by a single focused laser pulse and by two counter-propagating colliding focused pulses is analyzed. A focused laser pulse is described using a realistic three-dimensional model based on an exact solution of Maxwell's equations. In particular, this model reproduces an important property of focused beams, namely, the existence of two types of waves with a transverse electric or magnetic vector (e-or h-polarized wave, respectively). The dependence of the number of produced pairs on the radiation intensity and focusing parameter is studied. It has been shown that the number of pairs produced in the field of a single e-polarized pulse is many orders of magnitude larger than that for an h-polarized pulse. The pulse-intensity dependence of the number of pairs produced by a single pulse is so sharp that the total energy of pairs produced by the e-polarized pulse with intensity near the intensity I{sub S} 4.65 x 10{sup 29} W/cm{sup 2} characteristic of QED is comparable with the energy of the pulse itself. This circumstance imposes a natural physical bound on the maximum attainable intensity of a laser pulse. For the case of two colliding circularly polarized pulses, it is shown that pair production becomes experimentally observable when the intensity of each beam is I {approx} 10{sup 26} W/cm{sup 2}, which is one to two orders of magnitude lower than that for a single pulse.

Bulanov, S. S. [Institute of Theoretical and Experimental Physics (Russian Federation)], E-mail: bulanov@itep.ru; Narozhny, N. B., E-mail: narozhny@theor.mephi.ru; Mur, V. D. [Moscow Engineering Physics Institute (State University) (Russian Federation); Popov, V. S. [Institute of Theoretical and Experimental Physics (Russian Federation)

2006-01-15

144

Influence on electron coherence from quantum electromagnetic fields in the presence of conducting plates  

E-print Network

The influence of electromagnetic vacuum fluctuations in the presence of the perfectly conducting plate on electrons is studied with an interference experiment. The evolution of the reduced density matrix of the electron is derived by the method of influence functional. We find that the plate boundary anisotropically modifies vacuum fluctuations that in turn affect the electron coherence. The path plane of the interference is chosen either parallel or normal to the plate. In the vicinity of the plate, we show that the coherence between electrons due to the boundary is enhanced in the parallel configuration, but reduced in the normal case. The presence of the second parallel plate is found to boost these effects. The potential relation between the amplitude change and phase shift of interference fringes is pointed out. The finite conductivity effect on electron coherence is discussed.

Jen-Tsung Hsiang; Da-Shin Lee

2005-12-06

145

Electron and phonon cooling in a superconductor-normal-metal-superconductor tunnel junction.  

PubMed

We present evidence for the cooling of normal-metal phonons, in addition to the well-known electron cooling, by electron tunneling in a superconductor-normal-metal-superconductor tunnel junction. The normal-metal electron temperature is extracted by comparing the device current-voltage characteristics to the theoretical prediction. We use a quantitative model for the heat transfer that includes the electron-phonon coupling in the normal metal and the Kapitza resistance between the substrate and the metal. It gives a very good fit to the data and enables us to extract an effective phonon temperature in the normal metal. PMID:17678393

Rajauria, Sukumar; Luo, P S; Fournier, T; Hekking, F W J; Courtois, H; Pannetier, B

2007-07-27

146

Sub-50-mK Electronic Cooling with Large-Area Superconducting Tunnel Junctions  

NASA Astrophysics Data System (ADS)

In electronic cooling with superconducting tunnel junctions, the cooling power is counterbalanced by the interaction with phonons and by the heat flow from the overheated leads. We study aluminum-based coolers that are equipped with a suspended normal metal and an efficient quasiparticle drain. At intermediate temperatures, the phonon bath of the suspended normal metal is cooled. By adjusting the junction transparency, we control the injection current and, thus, the temperature of the superconducting lead at the optimum cooling point. The best device shows remarkable cooling from 150 mK down to about 30 mK, a factor of 5 in temperature at a power of 40 pW. We discuss heat transport in our device and the reasons for cooling saturation at the low-temperature end.

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

2014-11-01

147

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

148

Coupling of electrons to the electromagnetic field in a localized basis  

E-print Network

Coupling of electrons to the electromagnetic field in a localized basis Roland E. Allen* Department of Physics, Texas A&M University, College Station, Texas 77843, USA #1;Received 3 June 2008; revised manuscript received 26 July 2008; published...? simulations for treating problems where standard Ehrenfest simulations will fail. DOI: 10.1103/PhysRevB.78.064305 PACS number#1;s#2;: 78.20.Bh, 71.15.Pd It is now possible to perform first-principles simulations of the coupled dynamics of electrons...

Allen, Roland E.

2008-01-01

149

Coupling of electrons to the electromagnetic field in a localized basis  

E-print Network

A simple formula is obtained for coupling electrons in a complex system to the electromagnetic field. It includes the effect of intra-atomic excitations and nuclear motion, and can be applied in. e.g., first-principles-based simulations of the coupled dynamics of electrons and nuclei in materials and molecules responding to ultrashort laser pulses. Some additional aspects of nonadiabatic dynamical simulations are also discussed, including the potential of "reduced Ehrenfest'" simulations for treating problems where standard Ehrenfest simulations will fail.

Roland E. Allen

2008-05-26

150

Gain-enhanced free-electron laser with an electromagnetic pump field  

NASA Technical Reports Server (NTRS)

The feasibility of enhancing the gain for the free electron laser (FEL) with an electromagnetic (EM) pump field has been considered. The enhancement is provided by reacceleration of the electrons in the interaction region by means of a static, axial electric field. A FEL utilizing a low energy electron beam and a wiggler magnet with a periodicity on the order of 1 cm would produce far infared (FIR) radiation with wavelengths on the order of a few hundred microns. The use of the FIR radiation as the pump field in a two-stage FEL is envisioned to obtain visible radiation with a low energy electron beam. A summary is provided regarding the theory and equations of motion for the EM-pumped FEL. The derived relations are applied to the second stage of such a two-stage FEL. The obtained equations have been incorporated into a computer code which has been used to calculate laser gain and energy conversion efficiency.

Hiddleston, H. R.; Segall, S. B.; Catella, G. C.

1982-01-01

151

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

152

Transmission of electromagnetic waves through a two-layer plasma structure with spatially nonuniform electron density.  

PubMed

Transmission of a p-polarized electromagnetic wave through a two-layer plasma structure with spatially nonuniform distributions of electron density in the layers is studied. The case, when the electromagnetic wave is obliquely incident on the structure and is evanescent in both plasma layers, is considered. The conditions for total transparency of the two-layer structure are found for the thin slab case and when the plasma inhomogeneity is weak. It is shown that the transmission coefficient of the p-polarized wave can be about unity, even if the plasma inhomogeneity is large. The effects of plasma inhomogeneity on transparency of the structure are more important if the slabs are thick, comparing with the case of thin layers. PMID:23214891

Denysenko, I B; Ivko, S; Smolyakov, A; Azarenkov, N A

2012-11-01

153

Electromagnetic wave instability in a relativistic electron-positron-ion plasma  

NASA Astrophysics Data System (ADS)

By employing the anisotropic plasma distribution function, the stability of circularly polarized electromagnetic (EM) waves is studied in a relativistically hot electron-positron-ion (e-p-i) plasma, investigating two specific scenarios. First, linear dispersion relations associated with the transverse EM waves are analyzed in different possible frequency regimes. The expression of the aperiodic hydrodynamic instability is obtained and numerically the transverse EM modes are shown to grow exponentially. Secondly, we have found that the transverse electromagnetic wave interact with a collisionless anisotropic e-p-i plasma and damp through the nonlinear Landau damping phenomena. Taking the effects of the latter into consideration, a kinetic nonlinear Schrödinger equation is derived with local and nonlocal nonlinearities, computing the damping rates. The present work should be helpful to understand the linear and nonlinear properties of the intense EM waves in hot relativistically astrophysical plasmas, e.g., pulsars, black holes, neutron stars, etc.

Rozina, C.; Tsintsadze, N. L.; Jamil, M.; Rasheed, A.; Ali, S.

2014-10-01

154

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

SciTech Connect

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

Chen, S. H.; Tai, L. C.; Liu, Y. L. [Department of Physics, National Central University, Jhongli 32001, Taiwan (China); Ang, L. K. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Koh, W. S. [Institute of High Performance Computing, A-STAR, Singapore 138632 (Singapore)

2011-02-15

155

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

156

Modeling of a microchannel evaporator for space electronics cooling: entropy generation minimization approach  

Microsoft Academic Search

The increasing heat dissipation from electronic devices on board satellites makes it necessary to find solutions for their cooling. In the present case, twenty electronic components in series need to dissipate a heat flux of 20 kW\\/m owing to microevaporators mounted in a refrigeration system. An approach for optimizing the design of the evaporators based on the entropy generation minimization

Pablo Bermejo; Rémi Revellin; Romain Charnay; Oliver Garbrecht; Julien Hugon; Jocelyn Bonjour

2013-01-01

157

Limitations in cooling electrons using normal-metal-superconductor tunnel junctions.  

PubMed

We demonstrate both theoretically and experimentally two limiting factors in cooling electrons using biased tunnel junctions to extract heat from a normal metal into a superconductor. First, when the injection rate of electrons exceeds the internal relaxation rate in the metal to be cooled, the electrons do not obey the Fermi-Dirac distribution, and the concept of temperature cannot be applied as such. Second, at low bath temperatures, states within the gap induce anomalous heating and yield a theoretical limit of the achievable minimum temperature. PMID:14995329

Pekola, J P; Heikkilä, T T; Savin, A M; Flyktman, J T; Giazotto, F; Hekking, F W J

2004-02-01

158

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

159

Heat transfer enhancement using Al 2O 3–water nanofluid for an electronic liquid cooling system  

Microsoft Academic Search

We have experimentally investigated the behaviour and heat transfer enhancement of a particular nanofluid, Al2O3 nanoparticle–water mixture, flowing inside a closed system that is destined for cooling of microprocessors or other electronic components. Experimental data, obtained for turbulent flow regime, have clearly shown that the inclusion of nanoparticles into distilled water has produced a considerable enhancement of the cooling block

Cong Tam Nguyen; Gilles Roy; Christian Gauthier; Nicolas Galanis

2007-01-01

160

Forced Convective Cooling of Foils in a Repetitively Pulsed Electron-Beam Diode  

Microsoft Academic Search

Electron-beam (e-beam)-pumped high-power gas lasers require the use of a transmission window\\/foil to separate the vacuum diode from the laser cell. Under repetitive operation, the foil is subject to an e-beam heat load and would eventually fail without cooling. This paper investigates forced convective cooling of a foil in the main amplifier of the Electra KrF laser by flowing the

Frank Hegeler; John L. Giuliani; John D. Sethian; Matthew C. Myers; Matthew F. Wolford; Patrick M. Burns; Moshe Friedman

2008-01-01

161

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

162

Particle-in-cell simulations of electromagnetic turbulence with kinetic electrons  

NASA Astrophysics Data System (ADS)

The accurate treatment of electron dynamics in global (toroidal) particle-in-cell simulations is a considerable challenge from the numerical standpoint. The large thermal velocity of the (transit) electrons imposes a stringent condition on the time step for a brute force method. In the electrostatic case, it has been shown that the splitting scheme [1] for the electron dynamics is more accurate, both in the linear and nonlinear regimes, that the conventional perturbative delta f scheme. We present the electromagnetic version of the splitting scheme and specifically discuss the issues of energy and momentum conservation properties, the importance of the initial loading in phase space [2], and the spatial and time resolution requirements.[1] J.L.V. Lewandowski, Physics of Plasmas, 8, 3204 (2003).[2] J.L.V. Lewandowski, Physics Letters A, 313, 291 (2003).

Lewandowski, Jerome

2006-04-01

163

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

164

Perpendicular propagating electromagnetic envelope solitons in electron-positron-ion plasma  

SciTech Connect

The nonlinear amplitude modulation of electromagnetic waves propagating perpendicular to the direction of ambient magnetic field in a uniform collisionless magnetized electron-positron-ion plasma is studied. The Krylov-Bogoliubov-Mitropolsky perturbation method is employed to derive nonlinear Schroedinger equation, which describes the amplitude dynamics of perturbed magnetic field. The modulation instability criterion reveals that the low frequency mode is always stable, whereas the high frequency mode becomes modulationally unstable for certain ranges of wave number and positron-to-electron density ratio. Furthermore, the positron-to-electron density ratio as well as the strength of ambient magnetic field is found to have significant effect on the solitary wave solutions of the nonlinear Schroedinger equation, namely, dark and bright envelope solitons.

Jehan, Nusrat [Department of Physics, Theoretical Plasma Physics Group, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Pakistan Atomic Energy Commission, P.O. Box 1114, Islamabad 44000 (Pakistan); Salahuddin, M. [Pakistan Atomic Energy Commission, P.O. Box 1114, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Department of Physics, Theoretical Plasma Physics Group, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2010-05-15

165

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

PubMed

Nonlinear propagation of fast and slow magnetosonic perturbation modes in an ultrarelativistic, ultracold, degenerate (extremely dense) electron positron (EP) plasma (containing ultrarelativistic, ultracold, degenerate electron and positron fluids) has been investigated by the reductive perturbation method. The Alfvén wave velocity is modified due to the presence of the enthalpy correction in the fluid equations of motion. The degenerate EP plasma system (under consideration) supports the Korteweg-de Vries (KdV) solitons, which are associated with either fast or slow magnetosonic perturbation modes. It is found that the ultrarelativistic model leads to compressive (rarefactive) electromagnetic solitons corresponding to the fast (slow) wave mode. There are certain critical angles, ?(c), at which no soliton solution is found corresponding to the fast wave mode. For the slow mode, the magnetic-field intensity affects both the soliton amplitude and width. It is also illustrated that the basic features of the electromagnetic solitary structures, which are found to exist in such a degenerate EP plasma, are significantly modified by the effects of enthalpy correction, electron and positron degeneracy, magnetic-field strength, and the relativistic effect. The applications of the results in a pair-plasma medium, which occurs in many astrophysical objects (e.g., pulsars, white dwarfs, and neutron stars) are briefly discussed. PMID:22463336

El-Taibany, W F; Mamun, A A

2012-02-01

166

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

167

Latitudinal dependence of nonlinear interaction between electromagnetic ion cyclotron wave and radiation belt relativistic electrons  

NASA Astrophysics Data System (ADS)

Electromagnetic ion cyclotron (EMIC) waves are long suggested to account for the rapid loss of radiation belt relativistic electrons. Here we perform both theoretical analysis and numerical simulation to comprehensively investigate the nonlinear interaction between EMIC wave and relativistic electrons. In particular, we emphasize the dependence of nonlinear processes on the electron initial latitude. The nonlinear phase trapping yields negative equatorial pitch angle transport, with efficiency varying over the electron initial latitude, implying that it can increase the loss rate predicted by quasilinear theory. The nonlinear channel effect phase bunching produces positive equatorial pitch angle transport, less dependent on the electron initial latitude, suggesting that it can decrease the loss rate predicted by quasilinear theory. The nonlinear cluster effect phase bunching alternately causes positive and negative equatorial pitch angle transport, quasi-periodically dependent on the electron initial latitude, suggesting that it can either decrease or increase the loss rate predicted by the quasilinear theory. Such latitudinal dependence of nonlinear processes should be taken into account in the evaluation of radiation belt electron loss rate driven by EMIC waves.

Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zheng, Huinan; Shen, Chao; Wang, Yuming; Wang, Shui

2013-06-01

168

PCB-Integrated Heat Exchanger for Cooling Electronics Using Microchannels Fabricated With the Direct-Write Method  

Microsoft Academic Search

The electronic industry has a growing need for efficient heat dissipation mechanisms such as micro heat exchanger systems. This active cooling approach requires the integration of microfluidic components near the main heat sources of the electronic devices. Despite the investigation of several micro-cooling configurations, their commercial utilization by the electronic industry is rather limited due to complex fabrication and integration

Ramzi Bey Oueslati; Daniel Therriault; Sylvain Martel

2008-01-01

169

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

NASA Astrophysics Data System (ADS)

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

2014-09-01

170

Chaotic behavior of nonlinearly coupled electrostatic and electromagnetic modes in electron-positron-ion magnetoplasma with equilibrium flows  

SciTech Connect

A new set of nonlinear equations has been derived to study the temporal behavior of low frequency electrostatic and electromagnetic ion-temperature-gradient driven modes in an electron-positron-ion (e-p-i) magnetoplasma. The temporal behavior of the nonlinear mode coupling equations, under certain conditions, are governed by the coupled equations, which are the generalization of Lorenz and Stenflo type equations, admitting chaotic behavior. The linear stability of the generalized Lorenz-Stenflo system of equations is also presented for electrostatic and electromagnetic cases. The results of present investigation should be useful to understand the nonlinear properties of electromagnetic/electrostatic waves in an e-p-i magnetoplasma.

Azeem, M.; Mirza, Arshad M. [Theoretical Plasma Physics Group, Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2006-06-15

171

Influence of non-linear interactions on electromagnetic-field propagation in quantized many-electron systems  

NASA Astrophysics Data System (ADS)

Non-linear interactions involving pump-probe optical phenomena, such as electromagnetically induced transparency, in quantized many-electron systems are investigated using a reduced-density-matrix approach. Time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations are developed in a unified manner and self-consistent manner. The standard Born (lowest-order perturbation-theory) and Markov (short-memory-time) approximations are systematically introduced within the framework of the general non-perturbative and non-Markovian formulations. A preliminary semiclassical perturbation-theory treatment of the electromagnetic interaction is adopted. However, it is emphasized that a quantized-electromagnetic-field approach is essential for a self-consistent quantum-mechanical formulation. Our primary result is the derivation of compact Liouville-space operator expressions for the linear and the general (n'th order) non-linear macroscopic electromagnetic-response tensors for moving many-electron system. These expressions can be evaluated for coherent initial electronic excitations and for the full tetradic-matrix form of the Liouville-space self-energy operator representing the environmental interactions in the Markov approximation. Environmental interactions can be treated in various approximations for the self-energy operator, and the influence of Zeeman coherences on electromagnetic-field propagation can be investigated by including an applied magnetic field on an equal footing with the electromagnetic fields.

Jacobs, Verne L.

2011-03-01

172

Neutrino pair emission off electrons in a strong electromagnetic wave field  

SciTech Connect

The emission of {nu}{nu} pairs off electrons in a polarized ultraintense electromagnetic (e.g., laser) wave field is analyzed. We elaborate on the significance of nonlinear electrodynamics effects (i.e., multiphoton processes) and the peculiarities of neutrino production. Special attention is devoted to the convergence of the reaction probabilities as a function of the number of absorbed photons. Expressions for large field intensities are provided. The asymmetry between the probabilities of electron and {mu}+{tau} neutrino production depends on initial conditions such as energy of the wave field photons and the field intensity. These findings differ from the lowest-order perturbative calculation of the reaction {gamma}+e{yields}e{sup '}+{nu}{nu}.

Titov, A. I. [Forschungzentrum Dresden-Rossendorf, 01314 Dresden (Germany); Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna 141980 (Russian Federation); Institute of Laser Engineering, Yamada-oka, Suita, Osaka 565-0871 (Japan); Kaempfer, B. [Forschungzentrum Dresden-Rossendorf, 01314 Dresden (Germany); Institut fuer Theoretische Physik, TU Dresden, 01062 Dresden (Germany); Takabe, H. [Institute of Laser Engineering, Yamada-oka, Suita, Osaka 565-0871 (Japan); Hosaka, A. [Research Center of Nuclear Physics, 10-1 Mihogaoka Ibaraki, 567-0047 Osaka (Japan)

2011-03-01

173

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

174

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

NASA Technical Reports Server (NTRS)

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

Hizanidis, Kyriakos

1989-01-01

175

Comment on ''Chaotic electron trajectories in an electromagnetic wiggler free-electron laser with ion-channel guiding'' [Phys. Plasmas 17, 093103 (2010)  

SciTech Connect

The chaotic electron dynamics in a free-electron laser with electromagnetic-wave wiggler and ion-channel has been recently reported by A. Taghavi et al.[Phys. Plasmas 17, 093103 (2010)]. We comment on the authors use of a set of initial condition that is not correct based on the dispersion relation and steady-state orbits.

Nasr, N.; Hasanbeigi, A. [Department of Physics and Institute for Plasma Research, Tarbiat Moallem University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

2011-05-15

176

Dispersion relation and growth rate in electromagnetically pumped free-electron lasers with ion-channel guiding  

SciTech Connect

A theory of electromagnetic-wave wiggler with ion-channel guiding is presented. Steady-state electron trajectories are obtained by solving the equations of motion for a single electron in a free-electron laser with electromagnetic-wave wiggler and ion-channel guiding field. The eighth-degree polynomial dispersion equation for electromagnetic and space charge waves in this configuration is derived. The characteristics of dispersion relation are analyzed in detail by numerical solutions. It is found that the growth rate for group I and II orbits has been affected by the presence of the ion-channel guiding and the growth rate for group II orbits is more affected.

Mehdian, H.; Hasanbeigi, A.; Jafari, S. [Department of Physics and Institute for Plasma Research, Tarbiat Moallem University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

2008-07-15

177

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

178

Passive cooling of electronic equipment rooms-thermal diode room construction  

Microsoft Academic Search

The authors introduce new technology for passive cooling of electronic equipment enclosures. The novel approach is simplistic and based on proven technology and does not pollute the atmosphere or require the use of electricity or the burning of fossil fuels. Details of the successful prototype vacuum panel heat exchanger (VPHE) and test rig are outlined together with the methodology for

R. K. Prudhoe; R. Henshaw; L. Doukas; R. Snow

1991-01-01

179

Large bandwidth and low noise in a diffusion-cooled hot-electron bolometer mixer  

E-print Network

Large bandwidth and low noise in a diffusion-cooled hot-electron bolometer mixer A. Skalare,a) W. R. McGrath, B. Bumble, and H. G. LeDuc Center for Space Microelectronics Technology, Jet Propulsion, indicating a receiver noise temperature of 650 K DSB. The 3 dB rolloff in the if response occurs at 1.7 GHz

Devoret, Michel H.

180

Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers  

E-print Network

Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers P. J, and H. G. LeDuc Center for Space Microelectronics Technology, Jet Propulsion Laboratory, Caltech study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot

Devoret, Michel H.

181

CFD for Electronics Cooling: MCAD and EDA embedded vs. stand-alone  

Microsoft Academic Search

Computational fluid dynamics (CFD) for electronics cooling (EC) has developed differently from general-purpose CFD, due to the nature of the market it serves. The benefits are clear - the use of EC CFD in product design has had a profound impact on both time-to-market and cost.

John D. Parry

2008-01-01

182

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

SciTech Connect

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

Kazinski, P.O., E-mail: kpo@phys.tsu.ru

2013-12-15

183

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

SciTech Connect

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

Mirzanejhad, Saeed; Sohbatzadeh, Farshad; Ghasemi, Maede; Sedaghat, Zeinab; Mahdian, Zeinab [Department of Physics, Faculty of Science, Mazandaran University, 47416-95447 Babolsar (Iran, Islamic Republic of)

2010-05-15

184

Micromachined cryogenic cooler for cooling electronic devices down to 30 K  

NASA Astrophysics Data System (ADS)

Cryogenic temperatures are required for improving the performance of electronic devices and for operating superconducting sensors and circuits. The broad implementation of cooling these devices has long been constrained by the availability of reliable and low cost cryocoolers. After the successful development of single-stage micromachined coolers able to cool to 100 K, we now present a micromachined two-stage microcooler that cools down to 30 K from an ambient temperature of 295 K. The first stage of the microcooler operates at about 94 K with nitrogen gas and pre-cools the second stage operating with hydrogen gas. The microcooler is made from just three glass wafers and operates with modest high-pressure gases and without moving parts facilitating high yield fabrication of these microcoolers. We have successfully cooled a YBCO film through its superconducting transition state to demonstrate a load on the microcooler at cryogenic temperatures. This work could expedite the application of superconducting and electronic sensors and detectors among others in medical and space applications.

Cao, H. S.; Holland, H. J.; Vermeer, C. H.; Vanapalli, S.; Lerou, P. P. P. M.; Blom, M.; ter Brake, H. J. M.

2013-02-01

185

Liquid Cooled Cold Plates for Industrial High-Power Electronic Devices---Thermal Design and Manufacturing Considerations  

Microsoft Academic Search

Electronics cooling research has been largely focused on high heat flux removal from computer chips in the recent years. However, the equally important field of high-power electronic devices has been experiencing a major paradigm shift from air cooling to liquid cooling over the last decade. For example, multiple 250-W insulated-gate bipolar transistors used in a power drive for a 7000-HP

Satish G. Kandlikar; Clifford N. Hayner II

2009-01-01

186

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

187

Nonlinear Interaction of Relativistic Electrons and Electromagnetic Ion Cyclotron Waves in a Two-wave Model  

NASA Astrophysics Data System (ADS)

Nonlinear interaction of relativistic electrons with a monochromatic electromagnetic ion cyclotron wave was investigated extensively in previous studies. Here we extend this work to investigate wave particle interactions in a two-wave model. By varying the separation of the two wave numbers, we calculate the Chirikov parameter, which measures the degree of the overlap of the resonant islands in the phase portrait. We demonstrate that the resonant islands highly overlap over a large range of the wave number separation, depending on which three typical regimes are identified. 1) a degenerate regime in which the effect of the two waves can be approximated by one wave model; 2) a transition regime where the resonant latitude of one wave moves equatorward and finally drops out of resonance with the electrons; 3) a non-overlap region where one wave is resonant with the electrons and the other is not. In the degenerate region, the concepts from the single wave interaction, i.e., phase bunching and phase trapping, still apply. When the particle initial pitch angle or the wave amplitude decreases, the length of the range of the degenerate region increases. In the transition region, the motions of the electrons are stochastic. In the non-overlap region, only the resonant wave is responsible for the electron scattering while the nonresonant wave contributes little. As one important application in the realistic space environment, we demonstrate that EMIC wave interactions with electrons can be treated by a single wave if the range of wave frequencies is located inside the degenerate region.

An, X.; Chen, L.; Bortnik, J.; Thorne, R. M.

2013-12-01

188

Precipitation of relativistic electrons by interaction with electromagnetic ion cyclotron waves  

NASA Astrophysics Data System (ADS)

On August 20, 1996, balloon-borne X-ray detectors observed an intense X-ray event as part of a French balloon campaign near Kiruna, Sweden, at 1532 UT (1835 magnetic local time), on an L shell of 5.8. The energy spectrum of this event shows the presence of X rays with energies >1 MeV, which are best accounted for by atmospheric bremsstrahlung from monoenergetic ~1.7 MeV precipitating electrons. Ultraviolet images from the Polar satellite and energetic particle data from the Los Alamos geosynchronous satellites show the onset of a small magnetospheric substorm 24 min before the start of the relativistic electron precipitation event. Since the balloon was south of the auroral oval and there was no associated increase in relativistic electron flux at geosynchronous altitude, the event is interpreted as the result of selective precipitation of ambient relativistic electrons from the radiation belts. Pitch angle scattering caused by resonance with electromagnetic ion cyclotron mode waves is the most likely mechanism for selective precipitation of MeV electrons. A model is presented in which wave growth is driven by temperature anisotropies in the drifting substorm-injected proton population. The model predicts that this wave growth and resonance with ~1.7 MeV electrons will occur preferentially in regions of density >10 cm-3, such as inside the duskside plasmapause bulge or detached plasma regions. The model predictions are consistent with the location of the balloon, the observed energies, and the timing with respect to the substorm energetic particle injection.

Lorentzen, K. R.; McCarthy, M. P.; Parks, G. K.; Foat, J. E.; Millan, R. M.; Smith, D. M.; Lin, R. P.; Treilhou, J. P.

2000-03-01

189

ELECTROMAGNETIC SIMULATIONS OF DIELECTRIC WALL ACCELERATOR STRUCTURES FOR ELECTRON BEAM ACCELERATION  

SciTech Connect

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

Nelson, S D; Poole, B R

2005-05-05

190

Electromagnetic fields from pulsed electron beam experiments in space - Spacelab-2 results  

NASA Technical Reports Server (NTRS)

During the Spacelab-2 mission a small satellite carrying various plasma diagnostic instruments was released from the Shuttle to coorbit at distances up to 300 m. During a magnetic conjunction of the Shuttle and the satellite an electron beam modulated at 1.22 kHz was emitted from the Shuttle during a 7 min period. The spatial structure of the electromagnetic fields generated by the beam was observed from the satellite out to a distance of 153 m perpendicular to the beam. The magnetic field amplitude of the strongest harmonics were comparable to the amplitude of simultaneously observed whistlers, while the electric field amplitudes were estimated to 1-10 mV/m.

Bush, R. I.; Reeves, G. D.; Banks, P. M.; Neubert, T.; Williamson, P. R.

1987-01-01

191

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

192

Observation of electron plasma waves inside large amplitude electromagnetic pulses in a temporally growing plasma  

SciTech Connect

Observation of electron plasma waves excited inside high power ({approx}10 kW) short pulse ({approx}20 {mu}s) electromagnetic (em) waves interacting with a gaseous medium (argon) in the pressure range 0.2-2.5 mTorr is reported. The waves have long wavelength ({approx}13 cm) and get damped at time scales slower ({approx}3 {mu}s) than the plasma period (0.1-0.3 {mu}s), the energy conveyed to the medium lead to intense ionization (ion density n{sub i} {approx} 10{sup 11} cm{sup -3} and electron temperature T{sub e} {approx} 6-8 eV) and rapid growth of the plasma ({approx}10{sup 5} s{sup -1}) beyond the waves. Time frequency analysis of the generated oscillations indicate the presence of two principal frequencies centered around 3.8 MHz and 13.0 MHz with a spread {Delta}f {approx} 4 MHz, representing primarily two population of electrons in the plasma wave. The experimental results are in reasonable agreement with a model that considers spatiotemporal forces of the em wave on the medium, space charges and diffusion.

Pandey, Shail; Bhattacharjee, Sudeep; Sahu, Debaprasad [Department of Physics, Indian Institute of Technology, Kanpur-208016 (India)

2012-01-15

193

Simulation of electron cooling and intrabeam scattering processes of a heavy ion beam in HIRFL-CSR  

NASA Astrophysics Data System (ADS)

This paper is devoted to the simulation of electron cooling and intrabeam scattering processes of a heavy ion beam in the proposed HIRFL-CSR, according to the analytical cooling force formulae and the intrabeam scattering growth rate expressions. Some important effects like the betatron and synchrotron oscillations, and space charge effect of the electron beam have been considered. Time evolution of beam emittances and momentum spread under joint action of the electron cooling and intrabeam scattering are shown. The dependence of ion beam properties in equilibrium on the number of particles and the electron current are presented.

Rao, Y. N.; Katayama, T.

1997-02-01

194

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

195

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

196

Millimeter wave and infrared electronics for investigations of acoustic-electromagnetic phenomena due to activity of Popocatepetl volcano  

Microsoft Academic Search

The report is devoted to millimeter and sub millimeter electronics intended for research of acoustic-electromagnetic phenomena caused by Popocatepetl volcano (Mexico). The main purpose is to present different types of sensors, one of them is based on a red and infra red silicon detector (avalanche photodiode with separated regions of absorption and multiplication). This sensor guarantees both a good sensibility

M. Tecpoyotl-T; D. Solovyev; V. Grimalsky; A. Torres-J; J. De La Hidalga-W; Ya. Kishenko

2001-01-01

197

Gyrotrons and dopplertrons - Electromagnetic wave generators based on coherent radiation from magneto-resonant, relativistic, electron beams  

Microsoft Academic Search

The application of magnetized, intense, relativistic-electron beams to the generation of electromagnetic radiation at wavelengths ranging from 10 cm down to a fraction of a millimeter has enabled significant advances to be made in peak power capabilities. The physical mechanisms are conveniently divided into three categories according to the experimental feature which determines the output wavelength. These categories are related

V. L. Granatstein

1978-01-01

198

COOLING RATES FOR RELATIVISTIC ELECTRONS UNDERGOING COMPTON SCATTERING IN STRONG MAGNETIC FIELDS  

SciTech Connect

For inner magnetospheric models of hard X-ray and gamma-ray emission in high-field pulsars and magnetars, resonant Compton upscattering is anticipated to be the most efficient process for generating continuum radiation. This is in part due to the proximity of a hot soft photon bath from the stellar surface to putative radiation dissipation regions in the inner magnetosphere. Moreover, because the scattering process becomes resonant at the cyclotron frequency, the effective cross section exceeds the classical Thomson value by over two orders of magnitude, thereby enhancing the efficiency of continuum production and the cooling of relativistic electrons. This paper presents computations of the electron cooling rates for this process, which are needed for resonant Compton models of non-thermal radiation from such highly magnetized pulsars. The computed rates extend previous calculations of magnetic Thomson cooling to the domain of relativistic quantum effects, sampled near and above the quantum critical magnetic field of 44.13 TG. This is the first exposition of fully relativistic, quantum magnetic Compton cooling rates for electrons, and it employs both the traditional Johnson and Lippmann cross section and a newer Sokolov and Ternov (ST) formulation of Compton scattering in strong magnetic fields. Such ST formalism is formally correct for treating spin-dependent effects that are important in the cyclotron resonance and has not been addressed before in the context of cooling by Compton scattering. The QED effects are observed to profoundly lower the rates below extrapolations of the familiar magnetic Thomson results, as expected, when recoil and Klein-Nishina reductions become important.

Baring, Matthew G.; Wadiasingh, Zorawar [Department of Physics and Astronomy, MS 108, Rice University, Houston, TX 77251 (United States); Gonthier, Peter L., E-mail: baring@rice.edu, E-mail: zw1@rice.edu, E-mail: gonthier@hope.edu [Department of Physics, Hope College, 27 Graves Place, Holland, MI 49423 (United States)

2011-05-20

199

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

200

ASSESSMENT OF HIGH-PERFORMANCE COMPACT MICRO BARE-TUBE HEAT EXCHANGERS FOR ELECTRONIC EQUIPMENT COOLING  

Microsoft Academic Search

In the present study, a micro bare-tube heat exchanger without conventional fins is proposed and evaluated for electronic equipment cooling application. A micro bare-tube heat exchanger composed of 0.5mm outer diameter copper tubes is manufactured and tested experimentally. The optimal dimensionless transverse and longitudinal tube pitches were PT = 2.28 and PL = 1.31, respectively. It is shown that the

N. Kasagi; N. Shikazono; Y. Suzuki; T. Oku

201

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

202

Low Energy Electron Cooling and Accelerator Physics for the Heidelberg CSR  

NASA Astrophysics Data System (ADS)

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 ˜ 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.; von Hahn, R.; Orlov, D.; Schwalm, D.; Wolf, A.; Zajfman, D.

2006-03-01

203

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

204

Role of Non-Linear Interactions in Electromagnetic-Field Propagation through Moving Many-Electron Atomic Systems  

NASA Astrophysics Data System (ADS)

Reduced-density-matrix descriptions are developed for the propagation of electromagnetic fields through moving many-electron atomic systems, taking into account center-of-mass motions, atomic collision processes, and applied magnetic fields. Time-domain (equation-of-motion) and the frequency-domain (resolvent- operator) formulations are developed in a unified manner. A semiclassical perturbative treatment of the electromagnetic interaction is employed to derive compact Liouville- space operator expressions for the general n'th-order non-linear macroscopic electromagnetic-response tensors. Coherent atomic excitations and the full tetradic- matrix form of the collision-radiative self-energy operator in the Markov approximation are taken into account.

Jacobs, Verne

2011-06-01

205

Influence of Non-Linear Interactions on the Propagation of Electromagnetic Fields in Moving Many-Electron Atomic Systems  

NASA Astrophysics Data System (ADS)

Reduced-density-matrix descriptions are developed for the propagation of electromagnetic fields in moving many-electron atomic systems, taking into account the center-of-mass motions, atomic collision processes, and applied magnetic fields. The time-domain (equation-of-motion) and the frequency-domain (resolvent- operator) formulations are developed in a unified manner. A semiclassical perturbative treatment of the electromagnetic interaction is employed to derive compact Liouville- space operator expressions for the general n'th-order non-linear macroscopic electromagnetic-response tensors. Coherent atomic excitations and the full tetradic- matrix form of the collision-radiative self-energy operator in the Markov approximation are taken into account.

Jacobs, Verne

2011-03-01

206

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

207

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

NASA Technical Reports Server (NTRS)

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

Mellott, Ken

2004-01-01

208

Light and electron microscope studies of effects of 50 Hz electromagnetic fields on preincubated chick embryo.  

PubMed

We investigated the effects of an electromagnetic field (EMF) of 50 Hz, 1.33-7.32 mT on sections of preincubated white leghorn chicken embryos using light, SEM and TEM microscopes. Five hundred healthy, fresh, and fertilized eggs (55-65 g) were divided into three groups of experimental (n = 18-20), control (n = 60), and sham (n = 50). Experimental eggs (inside the coil) were exposed to 15 different intensities (1.33-7.32 mT) for morphological surveys and to the known most effective intensities for light, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. Sham groups were located inside the same coil with no exposure for 24 h before incubation. Control, sham, and experimental groups were then incubated in an incubator (38 +/- 0.5 degrees C, 60% humidity) for 4 days. At the end of this period, embryos were removed from their shells, prepared for morphometric, light, and SEM/TEM studies. Results of light microscopic studies (serial sections, 6mu) and morphometric data showed significant differences between different groups (P < 0.005). Larger and abnormal brain cavities, spina bifida, monophthalmia, microphthalmia, anophthalmia, and growth retardation were shown on SEM. TEM sections demonstrated that the nucleus was condensed, the nuclear envelope disappeared, and mitochondria degenerated. Golgi apparatus and endoplasmic reticulum were the least affected organelles. The Telencephlon was the most affected region, and the retina was altered more than the lens. We conclude that EMFs affect the brain, especially the Telencephalon and eye of preincubated-exposed chick embryo at the morphological and cellular level, nuclei are the most affected part, and our data agrees with "Ubeda's windows effects" of EMFs on preincubated chick embryos. PMID:17613036

Lahijani, M Shams; Nojooshi, S Ebrahimi; Siadat, S F

2007-01-01

209

ccsd-00005837,version2-10Jul2005 Partially ferromagnetic electromagnet for trapping and cooling neutral atoms to  

E-print Network

nanokelvins. To reach these ultra low temperatures and enter the quantum degeneracy regime, evaporative cool applications, such as inertial sen- sors in space [15], mandate the highest gradients for the lowest power configuration [22] because it avoids trap losses due to nonadiabatic spin flips: a quadrupolar lin- ear trap

Boyer, Edmond

210

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

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

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

SciTech Connect

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

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

2010-01-01

213

Characterization of electromagnetic fields in an extended chamber at the Short Pulse Experimental Electron Device (SPEED) simulator  

Microsoft Academic Search

The electromagnetic (EM) fields present during testing in a large vacuum chamber at the Short Pulse Experimental Electron Device (SPEED) facility are observed and measured using B-dot and D-dot detectors. Because the cathode of the vacuum diode is exposed to the chamber, the EM fields are significant and could adversely affect nonfaraday-shielded experiments. The differential magnetic fields and electric fields

Kenneth K. Hunt

1993-01-01

214

Influence of longitudinal space charge fields on the modulation process of coherent electron cooling  

NASA Astrophysics Data System (ADS)

The initial modulation in the scheme for coherent electron cooling (CeC) rests on the screening of the ion charge by electrons. However, in a CeC system with a bunched electron beam, inevitably, a long-range longitudinal space charge force is introduced. For a relatively dense electron beam, its force can be comparable to, or even greater than, the attractive force from the ions. Hence, the influence of the space charge field on the modulation process could be important. If the 3D Debye lengths are much smaller than the extension of the electron bunch, the modulation induced by the ion happens locally. Then, in that case, we can approximate the long-range longitudinal space charge field as a uniform electric field across the region. As detailed in this paper, we developed an analytical model to study the dynamics of ion shielding in the presence of a uniform electric field. We solved the coupled Vlasov-Poisson equation system for infinite anisotropic electron plasma, and estimated the influences of the longitudinal space charge field to the modulation process for the experimental proof of the CeC principle at the Relativistic Heavy Ion Collider.

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

2014-10-01

215

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

PubMed

We have constructed an apparatus combining the experimental techniques of cold target recoil ion momentum spectroscopy and a laser cooled target. We measure angle differential cross sections in Li(+)+Na-->Li+Na(+) electron transfer collisions in the keV energy regime with a momentum resolution of 0.12 a.u. yielding an order of magnitude better angular resolution than previous measurements. We resolve Fraunhofer-type diffraction patterns in the differential cross sections. Good agreement with predictions of the semiclassical impact parameter method is obtained. PMID:11580506

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

2001-09-17

216

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

SciTech Connect

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

Hershcovitch,A.

2009-03-01

217

Validation of convection-limited cooling of samples for freeze-fracture electron microscopy.  

PubMed

Rapid freezing is the most important step in sample preparation for freeze-fracture and other cryotechniques for electron microscopy. A simple heat transfer model is experimentally validated to show that convection from the cryogen to the specimen is the limiting step in rapid freezing of small samples [Biot modulus, (hd/k) less than 1] by measuring cooling rates in a variety of samples, materials, and cryogens. In comparison to the commonly accepted conduction-limited model, the convection-limited model predicts, and our experiments show, that cooling rates are proportional to the surface area to volume ratio, independent of the sample thermal conductivity, and inversely proportional to the product of sample density and heat capacity. We show that almost any material can be frozen at similar rates if the sample thickness, the cryogen, and the method and velocity of contact with cryogen are similar. Liquid ethane or propane cooled to liquid nitrogen temperature are shown to give the best results. PMID:1960713

Bailey, S M; Zasadzinski, J A

1991-09-01

218

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

219

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

220

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

221

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

SciTech Connect

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

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

2005-02-02

222

Electromagnetic Abdulaziz Hanif  

E-print Network

of these wire strands will be wrapped into a cable. This electromagnet is then super-cooled with liquid helium are better conductors and have a greater effect on the magnetic field. The plate would be charged up

Masoudi, Husain M.

223

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

PubMed

Research on scale inhibition is of importance to improve the heat transfer efficiency of heat exchangers. The combined effect of high voltage electrostatic and variable frequency pulsed electromagnetic fields on calcium carbonate precipitation was investigated, both theoretically and experimentally. Using energy dispersive spectrum analysis, the predominant phase was found to be CaCO(3). The formed crystal phases mainly consist of calcite and aragonite, which is, in part, verified by theory. The results indicate that the setting of water flow velocity, and high voltage electrostatic and variable frequency pulsed electromagnetic fields is very important. Favorable values of these parameters can have a significant anti-scaling effect, with 68.95% of anti-scaling ratio for scale sample 13, while unfavorable values do not affect scale inhibition, but rather promoted fouling, such as scale sample 6. By using scanning electron microscopy analysis, when the anti-scaling ratio is positive, the particle size of scale was found to become smaller than that of untreated sample and the morphology became loose. The X-ray diffraction results verify that the good combined effect favors the appearance and growth of aragonite and restrains its transition to calcite. The mechanism for scale reduction is discussed. PMID:25259497

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

2014-01-01

224

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

225

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

226

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

NASA Astrophysics Data System (ADS)

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

Tanaka, Sei'ichi; Okuyama, Katsuhiko

2010-04-01

227

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

228

Design and performance of the lattice-cooled hot-electron terahertz mixer  

NASA Astrophysics Data System (ADS)

We present the measurements and the theoretical model of the frequency-dependent noise temperature of a superconductor lattice-cooled hot-electron bolometer mixer in the terahertz frequency range. The increase of the noise temperature with frequency is a cumulative effect of the nonuniform distribution of the high-frequency current in the bolometer and the charge imbalance, which occurs at the edges of the normal domain and at the contacts with normal metal. We show that under optimal operation the fluctuation sensitivity of the mixer is determined by thermodynamic fluctuations of the noise power, whereas at small biases there appears additional noise, which is probably due to the flux flow. We propose the prescription of how to minimize the influence of the current distribution on the mixer performance.

Semenov, A. D.; Hübers, H.-W.; Schubert, J.; Gol'Tsman, G. N.; Elantiev, A. I.; Voronov, B. M.; Gershenzon, E. M.

2000-12-01

229

Feasibility and electromagnetic compatibility study of the ClearPEM front-end electronics for simultaneous PET-MR imaging  

NASA Astrophysics Data System (ADS)

In this work we present a first feasibility study of the ClearPEM technology for simultaneous PET-MR imaging. The mutual electromagnetic interference (EMI) effects between both systems were evaluated on a 7 T magnet by characterizing the response behavior of the ClearPEM detectors and front-end electronics to pulsed RF power and switched magnetic field gradients; and by analyzing the MR system performance degradation from noise pickup into the RF receiver chain, and from magnetic susceptibility artifacts caused by PET front-end materials.

Neves, J. A.; Bugalho, R.; Gruetter, R.; Magill, A. W.; Ortigão, C.; Silva, J. C.; Silva, R.; Varela, J.

2013-02-01

230

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

E-print Network

In previous paper we have shown that there is a special kind of nonlinear electrodynamics - Curvilinear Wave Electrodynamics (CWED), whose equations are mathematically equivalent to the equations of quantum electrodynamics. The purpose of the present paper is to show that in framework of CWED the known solutions of the nonlinear electromagnetic equations can be considered as the approximate solutions of the nonlinear equation of CWED. Another purpose of this paper is to show, that these solutions allow the description of electron-like particle of CWED as point of non-point particles, depending on mathematical approach.

Alexander G. Kyriakos

2005-03-09

231

Explicit general solutions to relativistic electron dynamics in plane-wave electromagnetic fields and simulations of ponderomotive acceleration  

NASA Astrophysics Data System (ADS)

This study examines single-particle electron motions in both a plane electromagnetic wave and a Gaussian focus in vacuum. Exact, explicit analytic expressions for relativistic electron trajectories in a plane wave are obtained, using the proper time as a parameter, in the general case of arbitrary initial positions and velocities. It is shown that previous analyses can be completed using the proper-time parameter. The conditions under which localized oscillatory motions ('figure-of-eight' orbits) occur are derived from the new solutions. The general solutions are also connected with the figure-of-eight orbits by a Lorentz transformation. The analytic solutions for arbitrary initial conditions and an arbitrary initial field phase can be used to determine the ranges of electron ejection angle and emerging electron energy in a vacuum laser accelerator, in which electrons are ejected externally, and provide a basis for explaining the spectrum of nonlinear Thomson scattering radiation. Numerical solutions are used for electron motions in the focus of a Gaussian laser beam, and the mean motion allows one to test a new expression for the relativistic ponderomotive force. It is suggested that plane wave solutions can provide a basis for approximating the orbital motion of particles in Gaussian beams.

Yang, J.-H.; Craxton, R. S.; Haines, M. G.

2011-12-01

232

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

NASA Astrophysics Data System (ADS)

The velocity space scattering of an anisotropic electron beam (T?b/T?b>1) flowing along a background magnetic field B0 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 B0, 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 nb/ne?0.05 and beam temperature anisotropies Tb ?/Tb ??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.; Cowee, M. M.; Liu, K.; Peter Gary, S.; Winske, D.

2014-04-01

233

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

234

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

235

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

236

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

237

A conceptual design for an actively cooled high-average-power electron-beam absorber [for space power applications  

Microsoft Academic Search

A conceptual design of an electron-beam absorber system that uses water as both an energy absorber and a cooling medium is presented. This configuration uses an aluminum window to separate the water absorber from a vacuum beamline. Such an arrangement has several desirable features. First, any necessary reconfiguration for an increase or decrease in run time and\\/or beam power is

J. Van Sant; R. R. Stone; R. Hedtke; S.-W. Kang; D. Ng

1989-01-01

238

Pulse pile-up recovery for the front-end electronics of the PANDA Electromagnetic Calorimeter  

NASA Astrophysics Data System (ADS)

At the future Facility for Antiproton and Ion Research near Darmstadt in Germany the PANDA detector will be employed to study the charmonium spectrum and to search for narrow exotic hadronic states, predicted by Quantum Chromodynamics. In the PANDA experiment, 1.5 to 15 GeV/c anti-protons will annihilate with a hydrogen target at an average rate of 20MHz. Among the sub-detectors of PANDA is the Electromagnetic Calorimeter (EMC) planned for the studies of electromagnetic transitions and neutral meson decays. Due to the high annihilation rates, the EMC will be exposed to single-detector hit rates up to 500kHz, which may lead to pulse overlap. Hence, to recover the energy and time information of the overlapping pulses, a pulse pile-up recovery method is developed. The method is easy to implement in FPGA for online data processing. The Constant Fraction Timing algorithm is applied at the trailing edge to determine the time stamp of pile-up pulses. The energy and the time information of pile-up pulses can be recovered up to time differences of 50ns, equal to the pulse rise-time, in a large dynamic energy range.

Tambave, G.; Kavatsyuk, M.; Guliyev, E.; Schreuder, F.; Moeini, H.; Löhner, H.

2012-11-01

239

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

240

Relativistic electron precipitation events driven by electromagnetic ion-cyclotron waves  

NASA Astrophysics Data System (ADS)

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

2014-08-01

241

Thermal effects on the propagation of large-amplitude electromagnetic waves in magnetized relativistic electron-positron plasma.  

PubMed

The propagation of circularly polarized electromagnetic waves along a constant background magnetic field in an electron-positron plasma is calculated by means of both a fluid and a kinetic theory treatment. In the fluid theory, relativistic effects are included in the particle motion, the wave field, and in the thermal motion by means of a function f, which depends only on the plasma temperature. In this work we analyze the consistency of the fluid results with those obtained from a kinetic treatment, based on the relativistic Vlasov equation. The corresponding kinetic dispersion relation is numerically studied for various temperatures, and results are compared with the fluid treatment. Analytic expressions for the Alfvén velocity are obtained for the fluid and kinetic models, and it is shown that, in the kinetic treatment, the Alfvén branch is suppressed for large temperatures. PMID:23004888

Domínguez, Macarena; Muñoz, Víctor; Valdivia, Juan Alejandro

2012-05-01

242

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

243

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

NASA Technical Reports Server (NTRS)

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

Englert, G. W.

1972-01-01

244

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

NASA Astrophysics Data System (ADS)

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

Bhattacharjee, Sudeep; Dey, Indranuj; Paul, Samit

2013-04-01

245

On ion gyro-harmonic structuring in the stimulated electromagnetic emission spectrum during second electron gyro-harmonic heating  

NASA Astrophysics Data System (ADS)

Recent observations show that, during ionospheric heating experiments at frequencies near the second electron gyro-harmonic, discrete spectral lines separated by harmonics of the ion-gyro frequency appear in the stimulated electromagnetic emission (SEE) spectrum within 1 kHz of the pump frequency. In addition to the ion gyro-harmonic structures, on occasion, a broadband downshifted emission is observed simultaneously with these spectral lines. Parametric decay of the pump field into upper hybrid/electron Bernstein (UH/EB) and low-frequency ion Bernstein (IB) and oblique ion acoustic (IA) modes is considered responsible for generation of these spectral features. Guided by predictions of an analytical model, a two-dimensional particle-in-cell (PIC) computational model is employed to study the nonlinear processes during such heating experiments. The critical parameters that affect the spectrum, such as whether discrete gyro-harmonic on broadband structures is observed, include angle of the pump field relative to the background magnetic field, pump field strength, and proximity of the pump frequency to the gyro-harmonic. Significant electron heating along the magnetic field is observed in the parameter regimes considered.

Samimi, A.; Scales, W. A.; Bernhardt, P. A.; Briczinski, S. J.; Selcher, C. A.; McCarrick, M. J.

2012-11-01

246

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

SciTech Connect

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

Bhattacharjee, Sudeep; Paul, Samit [Department of Physics, Indian Institute of Technology, Kanpur 208016, Uttar Pradesh (India); Dey, Indranuj [Kyushu University, Kasuga Kouen 6-1, Kasuga City, 816-8580 (Japan)

2013-04-15

247

Compton Electrons and Electromagnetic Pulse in Supernovae and Gamma-Ray Bursts  

E-print Network

When gamma-rays emerge from a central source they may undergo Compton scattering in surrounding matter. The resulting Compton-scattered electrons radiate. Coherent radiation by such Compton electrons follows nuclear explosions above the Earth's atmosphere. Particle acceleration in instabilities produced by Compton electron currents may explain the radio emission by SN1998bw. Bounds on coherent radiation are suggested for supernovae and gamma-ray bursts; these bounds are very high, but it is unknown if coherent radiation occurs in these objects.

J. I. Katz

1999-08-19

248

CERENKOV RADIATION: Quantum theory of stimulated Cerenkov radiation of transverse electromagnetic waves by a low-density electron beam in a medium  

NASA Astrophysics Data System (ADS)

The quantum theory of stimulated Cerenkov radiation of transverse electromagnetic waves by an electron beam in an anisotropic medium is presented. Relativistic quantum nonlinear equations of the Cerenkov beam instability are obtained. In the linear approximation, the quantum dispersion equation is derived and the instability growth increments are determined. The nonlinear problem of the saturation of the quantum Cerenkov beam instability is solved.

Kuzelev, Mikhail V.

2010-01-01

249

Rotational analysis of A2A1-X2E electronic transition of the jet-cooled methylthio radical  

Microsoft Academic Search

A set of molecular parameters describing both the X and A states of CH3S, has been obtained by a joint fitting of the rotationally resolved electronic transitions observed in a free-jet-cooled laser-induced fluorescence study of CH3S and an earlier microwave study of its X state. The present work shows that, because of incomplete information, nearly all of the previously reported

Yen-Chu Hsu; Xianming Liu; Terry A. Miller

1989-01-01

250

On the use of a small-scale two-phase thermosiphon to cool high-power electronics  

Microsoft Academic Search

An experimental and analytical investigation of the steady-state thermal-hydraulic operating characteristics of a small-scale two-phase thermosiphon cooling actual power electronics are presented. Boiling heat transfer coefficients and circulation mass velocities were measured while varying heat load and pressure. Both a plain and augmented riser structure, utilizing micro-fins and reentrant cavities, were simultaneously tested. The boiling heat transfer coefficients increased with

D. S. Schrage

1990-01-01

251

Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 2. Evaluation for VLF chorus, ELF hiss, and electromagnetic ion cyclotron waves  

Microsoft Academic Search

Outer zone radiation belt electrons can undergo gyroresonant interaction with various magnetospheric wave modes including whistler-mode chorus outside the plasmasphere and both whistler-mode hiss and electromagnetic ion cyclotron (EMIC) waves inside the plasmasphere. To evaluate timescales for electron momentum diffusion and pitch angle diffusion, we utilize bounce-averaged quasi-linear diffusion coefficients for field-aligned waves with a Gaussian frequency spectrum in a

Danny Summers; Binbin Ni; Nigel P. Meredith

2007-01-01

252

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

253

Geant4 physics processes for microdosimetry simulation: Very low energy electromagnetic models for electrons in silicon  

NASA Astrophysics Data System (ADS)

The Energy-Loss Function (ELF) of silicon is used to calculate differential and total inelastic cross-sections of incident electrons. The model is validated in the 50 eV-50 keV incident energy range by comparing the inelastic cross-sections, stopping powers, and ranges to experimental and calculated data from the literature. It is applicable down to 16.7 eV. The cross sections are then used to simulate low-energy electron tracks in silicon with Geant4, using a similar implementation as the Geant4-DNA extension; this new Geant4 extension is called MuElec. Generation of low-energy electrons is clearly seen. The obtained ranges are consistent with experimental data.

Valentin, A.; Raine, M.; Sauvestre, J.-E.; Gaillardin, M.; Paillet, P.

2012-10-01

254

Electromagnetic electron whistler-cyclotron instability in bi-Kappa distributed plasmas  

NASA Astrophysics Data System (ADS)

We discuss the threshold conditions of the electron-whistler cyclotron instability in anisotropic bi-Kappa distributed plasmas. In anisotropic plasmas far from Maxwellian equilibrium, this instability represents one of the most plausible constraints for the electron temperature anisotropy T(e,?) > T(e,?) (where ? and ? denote directions relative to the local stationary magnetic field). In the context of a suprathermal solar wind, where the electron populations are well fitted by the advanced Kappa distribution functions, these models are expected to provide a more realistic description for the critical stability conditions. The unstable solutions are derived exactly numerically for the full range of values of the plasma beta including both the solar wind and magnetospheric plasma conditions, providing accurate physical correlations between the maximum growth rates and the threshold conditions. The lowest thresholds, which are the most relevant for the marginal stability, are found to decrease with the increase in density of the suprathermal populations. This result is correlated with an opposite effect on the corresponding growth rates (at low anisotropies), because their maximum values are enhanced in the presence of suprathermal electrons. The new marginal thresholds calculated with a bi-Kappa model are expected to provide better predictions for the limits of the temperature anisotropy in the solar wind.

Michno, M.; Lazar, M.; Poedts, S.

2013-12-01

255

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 of frequencies. Simulation and measurement results showing good isolation in the stop bands of the EBGs pair cavities [2]. To the best knowledge of the authors, methods to counter GHz range of vertical noise

Swaminathan, Madhavan

256

Compact infrared free-electron lasers based on gyrotron-powered electromagnetic wigglers  

Microsoft Academic Search

Free-electron lasers (FELs) capable of operating in vibrational infrared (IR) (3 - 30 micrometer) regime have been developed at a small number of fixed sites around the world. However, there is a need for portable systems capable of operating in the 3 - 5 and 8 - 13 micrometer atmospheric windows for remote sensing applications. Wider use of FELs is

Arne W. Fliflet; Wallace M. Manheimer; Phillip Sprangle

1997-01-01

257

Development of Nbn Hot Electron Bolometric Mixer for Terahertz Frequencies: the Phonon-Cooled Version  

NASA Astrophysics Data System (ADS)

NbN HEB mixers represent a promising approach for achieving receiver noise temperatures of a few times the quantum noise limit at frequencies above 1 THz. NbN HEB devices have been shown to have sufficient bandwidth for applications in astronomy, remote sensing, and plasma diagnostics in the FIR range. The NbN HEB is a phonon cooled bolometer in which the energy is transfered from the hot electrons to the substrate via inelastic collisions with phonons. The development of an NbN HEB mixer contained two steps: (1) implementing mixing in a comparatively large 'direct-coupled' prototype device which required LO power of a few milliwatts, and (2) optimization of the first step by the development of an 'antenna-coupled' (quasi-optically coupled) device with an LO power level of less than one ? W. The LO power was coupled to the antenna via an extended hemispherical lens (1.3 mm in diameter). The design, fabrication, and measurement stages were performed by a collaborative effort between a Russian team from the Department of Physics at Moscow State Pedagogical University in Moscow, the Submillimeter Technology Laboratory at UMass/Lowell and the Department of Electrical and Computer Engineering at UMass/Amherst. Mixing at 2.5 THz was demonstrated for the first time using the direct-coupled device achieving an intrinsic conversion loss of 23 dB. Sufficient level of LO power coupling at four different frequencies was demonstrated with the antenna-coupled device. The antenna/lens configuration has performed as well as expected insuring coupling to LO power of less than one ?W. A 3 dB conversion gain was demonstrated with the antenna-coupled device using a laser LO at 1.56 THz with an IF frequency of 500 KHz. A second laser was utilized as the rf source. Noise temperature for the NbN HEB mixer receiver of 5800 K has been demonstrated over the 1.25-1.75 GHz IF band. The mixer temperature was 2500 K and the total conversion loss was 27 dB. Further optimization of the receiver configuration and device fabrication as well as additional development in mixer modeling will gradually lead to lower noise temperatures.

Gerecht, Eyal

258

Progress of a room temperature electron cyclotron resonance ion source using evaporative cooling technology at Institute of Modern Physicsa)  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

259

FPGA Implementation of the Power Electronic Converter Model for Real-Time Simulation of Electromagnetic Transients  

Microsoft Academic Search

This paper presents an enhanced implementation methodology for the associated discrete circuit model of a power-electronic converter in a field-programmable gate array-based real-time power systems simulator. The simulator is intended for the testing and performance evaluation of digital control\\/protection platforms based on the hardware-in-the-loop concept. The salient features of the proposed implementation are: 1) It eliminates the need for corrective

Mahmoud Matar; Reza Iravani

2010-01-01

260

Amplification of electromagnetic waves by a ring-beam distribution of moderately relativistic electrons  

NASA Technical Reports Server (NTRS)

The possibility of a new mechanism for the excitation of unstable modes in cold background plasmas is indicated in this paper. These beam-cyclotron modes are excited by the presence of the ring-beam distribution of suprathermal electrons. The usual eigenmode excitation of a cold plasma is reviewed, and the new type of instability is examined using a single-harmonic approximation and multiharmonic treatment.

Shi, B. R.; Gaffey, J. D., Jr.; Wu, C. S.

1986-01-01

261

Tunability enhanced electromagnetic wiggler  

DOEpatents

The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

Schlueter, Ross D. (Albany, CA); Deis, Gary A. (Livermore, CA)

1992-01-01

262

Tunability enhanced electromagnetic wiggler  

DOEpatents

The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

Schlueter, R.D.; Deis, G.A.

1992-03-24

263

Effect of Oblique Electromagnetic Ion Cyclotron Waves on Relativistic Electron Scattering: CRRES Based Calculation  

NASA Technical Reports Server (NTRS)

We consider the effect of oblique EMIC waves on relativistic electron scattering in the outer radiation belt using simultaneous observations of plasma and wave parameters from CRRES. The main findings can be s ummarized as follows: 1. In 1comparison with field-aligned waves, int ermediate and highly oblique distributions decrease the range of pitc h-angles subject to diffusion, and reduce the local scattering rate b y an order of magnitude at pitch-angles where the principle absolute value of n = 1 resonances operate. Oblique waves allow the absolute va lue of n > 1 resonances to operate, extending the range of local pitc h-angle diffusion down to the loss cone, and increasing the diffusion at lower pitch angles by orders of magnitude; 2. The local diffusion coefficients derived from CRRES data are qualitatively similar to the local results obtained for prescribed plasma/wave parameters. Conseq uently, it is likely that the bounce-averaged diffusion coefficients, if estimated from concurrent data, will exhibit the dependencies similar to those we found for model calculations; 3. In comparison with f ield-aligned waves, intermediate and highly oblique waves decrease th e bounce-averaged scattering rate near the edge of the equatorial lo ss cone by orders of magnitude if the electron energy does not excee d a threshold (approximately equal to 2 - 5 MeV) depending on specified plasma and/or wave parameters; 4. For greater electron energies_ ob lique waves operating the absolute value of n > 1 resonances are more effective and provide the same bounce_averaged diffusion rate near the loss cone as fiel_aligned waves do.

Gamayunov, K. V.; Khazanov, G. V.

2007-01-01

264

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

265

The heat and cooling of electronically switching synchronous machine as a main drive of a car  

Microsoft Academic Search

The electromobil or hybrid-electromobil is equipped by an electric machine. This machine can work in a generator mode or in a motor mode. Because the size and weight of this type of machine are very limited, it is necessary (during the drive) to overload this machine for a short time. Consequently, the cooling system, the winding insulation system and power

Bohumil Skala

2011-01-01

266

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

267

Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping.  

PubMed

A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ?10^{4}?_{pe}^{-1}. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock. PMID:25238365

Stockem, A; Grismayer, T; Fonseca, R A; Silva, L O

2014-09-01

268

Electromagnetic Field Generation in the Downstream of Electrostatic Shocks Due to Electron Trapping  

NASA Astrophysics Data System (ADS)

A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ˜104?pe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

Stockem, A.; Grismayer, T.; Fonseca, R. A.; Silva, L. O.

2014-09-01

269

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

270

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

271

Ground level signal strength of electromagnetic waves generated by pulsed electron beams in space  

NASA Astrophysics Data System (ADS)

A theoretical study has been made of the signal strengths at ground level of waves generated by pulsed electron beams in space. The radiated energy is first calculated by an improved version of a theory based on coherent spontaneous emission. This theory evaluates the electric and magnetic field strengths and power fluxes in the far field by applying asymptotic expansion techniques. The power flowing out within a cone whose apex is located at the gun position is calculated, and the intersection of the rays in this cone with the earth's surface is determined by using Snell's law considerations. Ground signal levels are calculated for typical ionospheric conditions as a function of pulsing frequency for fixed beam voltage and for voltage adjusted for resonance between the waves and the particles. For short beams, the ground level signal strengths are relatively insensitive to the wave particle resonance condition, but for longer beams the associated peaking of the signal level begins to be observed. Finally, these results are compared against ambient noise levels to determine under which circumstances these ground signals can be detected.

Harker, K. J.; Neubert, T.; Banks, P. M.; Fraser-Smith, A. C.; Donohue, D. J.

1991-11-01

272

Nonlinear quantum theory of stimulated Cherenkov radiation of transverse electromagnetic waves from a low-density relativistic electron beam in a dielectric medium  

SciTech Connect

A nonlinear quantum theory of stimulated Cherenkov radiation of transverse electromagnetic waves from a low-density relativistic electron beam in an isotropic dielectric medium is presented. A quantum model based on the Klein-Gordon equation is used. The growth rates of beam instabilities caused by the effect of stimulated Cherenkov radiation have been determined in the linear approximation. Mechanisms of the nonlinear saturation of relativistic quantum Cherenkov beam instabilities have been analyzed and the corresponding analytical solutions have been obtained.

Bobylev, Yu. B.; Kuzelev, M. V. [Moscow State University, Faculty of Physics (Russian Federation)

2012-06-15

273

Comment on ''Electron acceleration by a short laser beam in the presence of a long-wavelength electromagnetic wave'' [J. Appl. Phys. 102, 056106 (2007)  

SciTech Connect

Gupta et al.[J. Appl. Phys. 102, 056106 (2007)] investigated vacuum electron acceleration by a short laser beam in the presence of a long-wavelength electromagnetic wave. However, we consider that their simulation results to be questionable. We have investigated their simulation in detail and present our own simulation results, which do not match the good acceleration as theirs given in the original paper.

Yuan, C. J.; Wang, P. X. [Applied Ion Beam Physics Laboratory, Key Laboratory of the Ministry of Education, China and Department of Nuclear Science and Technology, Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Huang, S. J. [Department of Physics, Zhanjiang Normal University, Zhanjiang, Guangdong Province 524048 (China); Wang, J. X. [State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062 (China)

2012-05-15

274

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

275

Possible Modification of the Cooling Index of Helium Pickup Ions by Electron Impact Ionization in the Inner Heliosphere  

NASA Astrophysics Data System (ADS)

Interstellar neutrals penetrating into the inner heliosphere are ionized by photoionization, charge exchange with solar wind ions, and by electron impact ionization. This process is the first step in the generation of interstellar pickup ions. Usually, ionization rates are assumed to increase with 1/r**2 as a neutral particle approaches the Sun. This assumption is not exactly true for electron impact ionization, because the electron temperature increases with decreasing distance from the Sun. Furthermore, there are two distinct populations of electrons, the so-called 'core' and 'halo' populations with different thermal distributions and different radial gradients in temperature. In the classical model of Vasyliunas and Siscoe (1976) newborn pickup ions fill a sphere in velocity distribution in the outward moving solar wind frame. As this distribution moves away from the Sun, it expands and cools adiabatically, with an adiabatic expansion coefficient of 3/2. This expansion coefficient can be determined experimentally, e.g., with observations of the velocity distributions of He pickup ions with ACE/SWICS. In our effort, to determine the influence of different parameters on the variability of the adiabatic expansion coefficient, we find that the deviation of the electron impact ionization rate plays only a minor role. The effect amounts to less than 10% near solar minimum and to less than 3% near solar maximum.

Bochsler, P. A.; Chen, J.; Moebius, E.; Gloeckler, G.

2013-12-01

276

Frequency bandwidth and conversion loss of a semiconductor heterodyne receiver with phonon cooling of two-dimensional electrons  

SciTech Connect

The temperature and concentration dependences of the frequency bandwidth of terahertz heterodyne AlGaAs/GaAs detectors based on hot electron phenomena with phonon cooling of two-dimensional electrons have been measured by submillimeter spectroscopy with a high time resolution. At a temperature of 4.2 K, the frequency bandwidth at a level of 3 dB (f{sub 3dB}) is varied from 150 to 250 MHz with a change in the concentration n{sub s} according to the power law f{sub 3dB} {proportional_to} n{sub s}{sup -0.5} due to the dominant contribution of piezoelectric phonon scattering. The minimum conversion loss of the semiconductor heterodyne detector is obtained in structures with a high carrier mobility ({mu} > 3 x 10{sup 5} cm{sup 2} V{sup -1} s{sup -1} at 4.2 K).

Shangina, E. L., E-mail: shangina@rplab.ru; Smirnov, K. V.; Morozov, D. V.; Kovalyuk, V. V.; Gol'tsman, G. N.; Verevkin, A. A. [Moscow State Pedagogical University (Russian Federation); Toropov, A. I. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2010-11-15

277

Rotational analysis of A2A1-X2E electronic transition of the jet-cooled methylthio radical  

NASA Astrophysics Data System (ADS)

A set of molecular parameters describing both the X and A states of CH3S, has been obtained by a joint fitting of the rotationally resolved electronic transitions observed in a free-jet-cooled laser-induced fluorescence study of CH3S and an earlier microwave study of its X state. The present work shows that, because of incomplete information, nearly all of the previously reported molecular parameters for CH3S must be significantly revised. The present observations show an unusual electronic structure for the radical, characterized by a short C-S bond distance and peculiar methyl group geometry in the ground state. The C-S bond is observed to lengthen markedly in the excited A state.

Hsu, Yen-Chu; Liu, Xianming; Miller, Terry A.

1989-06-01

278

Experiment to measure the electric dipole moment (edm) of the electron using laser-cooled Cs atoms  

NASA Astrophysics Data System (ADS)

The electron edm de is known to be smaller in magnitude than 1.6x10-27e.cm [1]. We will describe progress on an ongoing experiment designed to be sensitive to an electron EDM de as small as 10-29e.cm. The experiment will search for the resulting edm of the Cs atom, proportional to de, using laser-cooled Cs atoms held in an optical dipole force trap. Important features of the experiment include resonant optical cavities to accurately define the trapping laser field, in-vacuum high voltage electrodes, and methods to reduce magnetic noise to low levels, including the use of a novel titanium vacuum chamber [4pt] [1] B. C. Regan et al. Phys. Rev. Lett. 88, 071805 (2002)

Ihn, Yong-Sup; Heinzen, Daniel

2010-03-01

279

Experimental investigation on flow and heat transfer performance of a novel heat fin-plate radiator for electronic cooling  

NASA Astrophysics Data System (ADS)

Within the electronics industry, high degree of integration and enhanced performance has led to high heat dissipation electronic devices. This has identified the future development of very high heat flux components. In this paper, a novel and high efficient diffusion welded heat fin-plate radiator (HFPR) was proposed and designed. Various parameters affect the thermal performance of HFPR. The effect of three parameters: the working fluid filling ratios (8% < FR < 70%), the vacuum degrees (0.001 Pa < VD < 0.1 Pa), and the air flow velocities (0.5 m/s < u < 6 m/s) were investigated experimentally. Using distilled water and ethanol as working fluids, a series of tests were carried out to find the influence of the above parameters on steady-state heat transfer characteristics of HFPR. The experimental results indicated that the filling ratio and vacuum degree had a significant influence on thermal performance of HFPR. Also compared with cooling performance using distilled water and ethanol, the HFPR cooling component using distilled water had a stronger heat dissipation capacity for the same filling ratio. The results also can provide a basis for optimal design of HFPR structure.

Peng, Hao; Ling, Xiang

2009-10-01

280

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

281

Quantum logic readout and cooling of a single dark electron spin  

NASA Astrophysics Data System (ADS)

We study a single dark N2 electron spin defect in diamond, which is magnetically coupled to a nearby nitrogen-vacancy (NV) center. We perform pulsed electron spin resonance on this single spin by mapping its state to the NV center spin and optically reading out the latter. Moreover, we show that the NV center's spin polarization can be transferred to the electron spin by combined two decoupling control-NOT gates. These two results allow us to extend the NV center's two key properties—optical spin polarization and detection—to any electron spin in its vicinity. This enables dark electron spins to be used as local quantum registers and engineerable memories.

Shi, Fazhan; Zhang, Qi; Naydenov, Boris; Jelezko, Fedor; Du, Jiangfeng; Reinhard, Friedemann; Wrachtrup, Jörg

2013-05-01

282

Compliance of the CERN electronics used by the LHC Cryogenic System with the Electromagnetic Compatibility (EMC) Norm IEC 61000 4-4  

E-print Network

Within the ITER-CERN collaboration agreement, task “PROCUREMENT OF CRYOGENIC THERMOMETERS TO MONITOR ITER MAGNETS AND FEEDER TEMPERATURES”, CERN is recommending the use by ITER of LHC like electronics for the temperature channels. ITER require that any electronic equipment shall be qualified according to the standard IEC 61000 4-4 that refers to the Electromagnetic compatibility (EMC), Part 4: Testing and measurement techniques, Section 4: Electrical fast transient/burst immunity test (EFT/B). This document describes the qualification procedure and the results for the LHC like temperature measurement chains according to the procedures described in the standard.

Casas, J

2011-01-01

283

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

284

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

285

Simplified equivalent modelling of electromagnetic emissions from printed circuit boards.  

E-print Network

??Characterization of electromagnetic emissions from printed circuit boards (PCBs) is an important issue in electromagnetic compatibility (EMC) design and analysis of modern electronic systems. This… (more)

Tong, Xin

2010-01-01

286

Cooling strategies for embedded electronic components of wearable computers fabricated by shape deposition manufacturing  

Microsoft Academic Search

Rugged, portable computers that can be comfortably worn on the body and easily operated for maintenance applications are being designed and manufactured at Carnegie Mellon University. The recently developed process of Shape Deposition Manufacturing has created the opportunity to embed the electronics of wearable computers in a polymer composite substrate. As both a protective outer case and a conductive heat

Eric Egan; Cristina H. Amon

1996-01-01

287

Assessment of Thermal Control Technologies for Cooling Electric Vehicle Power Electronics  

Microsoft Academic Search

The U.S. Department of Energy (DOE) FreedomCAR Program's technical targets for the electric traction system (power electronics and electric machines) of advanced vehicles require significant reductions in volume, weight, and cost while also meeting performance and 15 year life requirements (1). The performance of the semiconductor switches and diodes, the ripple-current capability of the capacitors, and the life of the

Thomas Abraham; Kevin Bennion; Desikan Bharathan; Sreekant Narumanchi; Michael O'Keefe

288

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 (NRH) will be presented. It examined sizes, locations, and fluxes of close to 10'000 decimetric Type III bursts. The flux study suggests that electron beams related to Type III emission could be responsible for carrying energy away from the corona in a proportion similar to that of EUV nanoflare heating. This tentative conclusion was reached from comparing Type III dN/dS distributions to the dN/dS of EUV/SXR nano-/micro-flares. The biggest uncertainty is the radiative efficiency, i.e. the ratio of radiated energy in decimetric Type III bursts and the energy of the electrons in the beams associated with them. We will constrain this value through other, new observations: we have already computed the amount of Type III radiated energy from NRH observations, and we will now compare them with the amount of energy in the corresponding beam electron detected in-situ by the Wind spacecraft. Given our sample of close to 10'000 decimetric Type IIIs, we expect a decent amount of in-situ beam energy estimates from magnetically connected events. Moreover, we will compare with X-ray-derived energies from corresponding RHESSI (micro)flares, when such an association exists.

Saint-Hilaire, Pascal; Wang, L.; Christe, S. D.; Vilmer, N.; Kerdraon, A.; Lin, R. P.

2012-05-01

289

"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

290

Characterisation of electromagnetic compatibility drifts of nanoscale integrated  

E-print Network

Characterisation of electromagnetic compatibility drifts of nanoscale integrated circuit after interferences. For the first time an electromagnetic compatibility (EMC) qualification procedure is proposed to increasing usage of high speed and complex electronic systems, electromagnetic compatibility (EMC) is a major

Paris-Sud XI, Université de

291

Effects of nonlocal plasmons in gapped graphene micro-ribbon array and two-dimensional electron gas on near-field electromagnetic response in the deep subwavelength regime.  

PubMed

A self-consistent theory involving Maxwell's equations and a density-matrix linear-response theory is solved for an electromagnetically coupled doped graphene micro-ribbon array (GMRA) and a quantum well (QW) electron gas sitting at an interface between a half-space of air and another half-space of a doped semiconductor substrate, which supports a surface-plasmon mode in our system. The coupling between a spatially modulated total electromagnetic (EM) field and the electron dynamics in a Dirac-cone of a graphene ribbon, as well as the coupling of the far-field specular and near-field higher-order diffraction modes, are included in the derived electron optical-response function. Full analytical expressions are obtained with nonlocality for the optical-response functions of a two-dimensional electron gas and a graphene layer with an induced bandgap, and are employed in our numerical calculations beyond the long-wavelength limit (Drude model). Both the near-field transmissivity and reflectivity spectra, as well as their dependence on different configurations of our system and on the array period, ribbon width, graphene chemical potential of QW electron gas and bandgap in graphene, are studied. Moreover, the transmitted E-field intensity distribution is calculated to demonstrate its connection to the mixing of specular and diffraction modes of the total EM field. An externally tunable EM coupling among the surface, conventional electron-gas and massless graphene intraband plasmon excitations is discovered and explained. Furthermore, a comparison is made between the dependence of the graphene-plasmon energy on the ribbon's width and chemical potential in this paper and the recent experimental observation given by [Nat. Nanotechnol.6, 630-634 (2011)] for a GMRA in the terahertz-frequency range. PMID:23385917

Huang, Danhong; Gumbs, Godfrey; Roslyak, Oleksiy

2013-02-01

292

NbN phonon-cooled hot-electron bolometer mixer for terahertz heterodyne receivers  

NASA Astrophysics Data System (ADS)

We present the results of our studies of NbN phonon-cooled HEB mixers at terahertz frequencies. The mixers were fabricated from NbN film deposited on a high-resistivity Si substrate with an MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 x 0.2 ?m2 active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. The largest gain bandwidth of 5.2 GHz was achieved for a mixer based on 2 nm thick NbN film deposited on MgO layer over Si substrate. The gain bandwidth of the mixer based on 3.5 nm NbN film deposited on Si with MgO is 4.2 GHz and the noise bandwidth for the same device amounts to 5 GHz. We also present the results of our research into decrease of the direct detection contribution to the measured Y-factor and a possible error of noise temperature calculation. The use of a square nickel cell mesh as an IR-filter enabled us to avoid the effect of direct detection and measure apparent value of the noise temperature which was 16% less than that obtained using conventional black polyethylene IR-filter.

Gol'tsman, Gregory N.; Vachtomin, Yuriy B.; Antipov, Sergey V.; Finkel, Matvey I.; Maslennikov, Sergey N.; Smirnov, Konstantin V.; Polyakov, Stanislav L.; Svechnikov, Sergey I.; Kaurova, Natalia S.; Grishina, Elisaveta V.; Voronov, Boris M.

2005-03-01

293

The radiation of electromagnetic waves and the instability of electrons moving at super-light velocity in a medium  

Microsoft Academic Search

The features of the radiation of electromagnetic waves by particles or systems (atoms, molecules, etc.) moving in a medium or near a medium (the moderating system) at super-light velocity can often be successfully analysed by applying quantum considerations, even when the problem is a classical one. This is also the case for the radiation, absorption and amplification of waves in

V. L. Ginzburg; V. V. Zheleznyakov; V. Ya. Eidman

1962-01-01

294

Electromagnetic radiation from positive-energy bound electrons in the Coulomb field of a nucleus at rest in a strong uniform magnetic field  

NASA Astrophysics Data System (ADS)

A classical analysis is presented of the electromagnetic radiation emitted by positive-energy electrons performing bound motion in the Coulomb field of a nucleus at rest in a strong uniform magnetic field. Bounded trajectories exist and span a wide range of velocity directions near the nucleus (compared to free trajectories with similar energies) when the electron Larmor radius is smaller than the distance at which the electron-nucleus Coulomb interaction energy is equal to the mechanical energy of an electron. The required conditions occur in magnetic white dwarf photospheres and have been achieved in experiments on production of antihydrogen. Under these conditions, the radiant power per unit volume emitted by positive-energy bound electrons is much higher than the analogous characteristic of bremsstrahlung (in particular, in thermal equilibrium) at frequencies that are below the electron cyclotron frequency but higher than the inverse transit time through the interaction region in a close collision in the absence of a magnetic field. The quantum energy discreteness of positive-energy bound states restricts the radiation from an ensemble of bound electrons (e.g., in thermal equilibrium) to nonoverlapping spectral lines, while continuum radiative transfer is dominated by linearly polarized bremsstrahlung.

Arsenyev, S. A.; Koryagin, S. A.

2012-06-01

295

Electromagnetic radiation from positive-energy bound electrons in the Coulomb field of a nucleus at rest in a strong uniform magnetic field  

SciTech Connect

A classical analysis is presented of the electromagnetic radiation emitted by positive-energy electrons performing bound motion in the Coulomb field of a nucleus at rest in a strong uniform magnetic field. Bounded trajectories exist and span a wide range of velocity directions near the nucleus (compared to free trajectories with similar energies) when the electron Larmor radius is smaller than the distance at which the electron-nucleus Coulomb interaction energy is equal to the mechanical energy of an electron. The required conditions occur in magnetic white dwarf photospheres and have been achieved in experiments on production of antihydrogen. Under these conditions, the radiant power per unit volume emitted by positive-energy bound electrons is much higher than the analogous characteristic of bremsstrahlung (in particular, in thermal equilibrium) at frequencies that are below the electron cyclotron frequency but higher than the inverse transit time through the interaction region in a close collision in the absence of a magnetic field. The quantum energy discreteness of positive-energy bound states restricts the radiation from an ensemble of bound electrons (e.g., in thermal equilibrium) to nonoverlapping spectral lines, while continuum radiative transfer is dominated by linearly polarized bremsstrahlung.

Arsenyev, S. A.; Koryagin, S. A., E-mail: koryagin@appl.sci-nnov.ru [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

2012-06-15

296

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

297

Stimulated electromagnetic emission and plasma line during pump wave frequency stepping near 4th electron gyroharmonic at HAARP  

NASA Astrophysics Data System (ADS)

Concurrent observations of stimulated (secondary) electromagnetic emissions (SEE) and incoherent plasma line (PL) backscatter from the MUIR radar during HF pumping of the ionosphere by the HAARP heating facility (62.4(°) °N, 145.15(°) W, magnetic inclination ? = 75.8^circ) with the pump wave (PW) frequency sweeps about the fourth electron gyroharmonic (4f_c) are presented. The PW frequency f0 was changed every 0.2 s in a 1-kHz step, i.e. with the rate of r_{f_0}=5 kHz/s. PW was transmitted at the magnetic zenith (MZ). Prior to sweeping, PW was transmitted continuously (CW) during 2 min at f_0 = 5730 kHz <4f_c to create the “preconditioned” ionosphere with small-scale magnetic field-aligned irregularities. During CW pumping, a typical SEE spectrum for f_0<4f_c, containing the prominent downshifted maxi?m (DM) shifted by Delta f_{DM} = f_{DM}-f_0approx-9 kHz, developed in 5-10 s after PW turn on. The PL echoes were observed during 2-3 s from the range dsim 220 km corresponding to the altitude slightly above PW reflection height. After sim5 s the PL echoes descended to dsim 210-212 km corresponding to the height h = d / (sinalpha) by sim 7 km below the height where f_0 = 4f_c. During frequency sweeps, two upshifted features appeared in the SEE spectrum for f_0> 4f_c, namely BUM_S and BUM_D. The former (stationary broad upshifted maxi?m) peaks at Delta f_{BUMs} approx f0 - nfc (d) + 15-20 kHz and is a typical SEE spectral feature. The latter, the dynamic BUM_D at smaller Delta f, is observed only at high pump powers (ERP=1.7 GW) and corresponds to artificial descending plasma layers created in the F-region ionosphere [1]. In the experiment in question, the BUM_D was present for f_0> f^*, where f^* was 5805-5815 kHz during stepping up and sim 10 kHz less for stepping down, and located 8-10 km below the background F-layer. The mini?m DM which indicated that f_0=4f_c=f_{uh} in the background ionospheric plasma, was sim 5760 kHz. The PL was observed only for f_0< f^* and mainly from altitudes h where f_0 <4f_c. The height h decreased with increasing f_0 in accordance with the altitude dependence 4f_c(h), the difference Delta f_g = f_0 - 4f_c was kept constant during either sweeping up [-(4-8 kHz)] or sweeping down [-(18-22 kHz)]. This corresponds to the difference between the altitude where f_0=4f_c and the PL generation altitude by Delta h sim 1.5-3 km and 7-8 km, respectively. During stepping up, the PL was observed also from the ranges where f_0 > 4f_c. In this case we obtained Delta f_g sim 8-13 kHz corresponding to Delta h sim - 4 km. The PL has never been observed for f_0>f^*$. \\ 1. Sergeev E., Grach S., et al. //Phys. Rev. Lett., 110 (2013), 065002.

Grach, Savely; Sergeev, Evgeny; Shindin, Alexey; Mishin, Evgeny; Watkins, Brenton

298

Anomalous electron cooling observed by the eiscat within the dusty nightside auroral dynamo layer  

NASA Astrophysics Data System (ADS)

In the present study we analyze parameters of the lower ionosphere, measured by the EISCAT radar facility at the zenith of Tromsø auroral observatory during the ERRRIS campaign. Data used consists of 20 different nights of observations and includes approximately 2000 measurements. At that 75% and 25% of the data corresponds to measured ionospheric electric field that is below and above the threshold of the Farley-Buneman instability (which is 15-20 mV/m), respectively. In the first part of our analysis the height profiles of the electron and ion temperature difference (Te-Ti) (including standard deviation, STD) for both, small and large electric fields were calculated using the superimposed epoch method. It was shown that: 1) for the large electric fields the profile (Te-Ti) with Te>Ti takes the maximum (60-70 K) at 115 km in agreement with the standard conception; 2) for the small electric fields the thermal anomaly was revealed when Teelectron temperature can decrease whilst the ion temperature increases.

Timofeev, Evgeny; Kangas, Jorma; Vallinkoski, Matti; Shalimov, Sergey

299

Cooling in a compound bucket  

SciTech Connect

Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results.

Shemyakin, A.; Bhat, C.; Broemmelsiek, D.; Burov, A.; Hu, M.; /Fermilab

2007-09-01

300

1578 IEEEJOURNAL OF QUANTUMELECTRONICS.VOL.QE-23, NO. 9. SEPTEMBER 1987 Free-Electron Lasers with Electromagnetic Standing  

E-print Network

1578 IEEEJOURNAL OF QUANTUMELECTRONICS.VOL.QE-23, NO. 9. SEPTEMBER 1987 Free-Electron Lasers of the electroniagnetic standing wave wiggler for free-electron lasers (FEL's) is conducted for both circular and linear codes developed for conventional FEL's. I.INTRODUCTION IN a free-electron laser (FEL), thecoherent

Wurtele, Jonathan

301

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

302

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

303

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 plasmons with the same frequency as the outside electromagnetic waves but with a much shorter wavelength

Atwater, Harry

304

A Magic Electromagnetic Field  

E-print Network

An electromagnetic field of simple algebraic structure is simply derived. It turns out to be the G=0 limit of the charged rotating Kerr-Newman metrics. These all have gyromagnetic ratio 2, the same as the Dirac electron. The charge and current distributions giving this high gyromagnetic ratio have charges of both signs rotating at close to the velocity of light. It is conjectured that something similar may occur in the quantum electrodynamic charge distribution surrounding the point electron.

Donald Lynden-Bell

2002-07-02

305

Design, Analysis and Fabrication of a Graphite\\/Epoxy Electronics Enclosure Flanged Aperture, with Supporting Electromagnetic Interference Test Data  

Microsoft Academic Search

The structural design of a rectangular metal electronics enclosure for airborne or space applications is straightforward and contained in a number of texts. However, the design of a composite electronics enclosure, optimized for weight and structural and thermal load paths, has not been addressed. In particular, the design of flanges that attach the walls to one another or the enclosure

Jack C. Roberts; Paul D. Wienhold

1995-01-01

306

Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies  

Microsoft Academic Search

In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55-1.1 THz frequency range. The best results of the double-sideband (DSB) noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path

P. Yagoubov; M. Kroug; H. Merkel; E. Kollberg; G. Gol'Tsman; S. Svechnikov; E. Gershenzon

1998-01-01

307

Electromagnetic effects on geodesic acoustic modes  

NASA Astrophysics Data System (ADS)

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 ?e, the safety factor q, and the temperature ratio ? on GAM dispersion are analyzed.

Bashir, M. F.; Smolyakov, A. I.; Elfimov, A. G.; Melnikov, A. V.; Murtaza, G.

2014-08-01

308

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

309

Stochastic cooling  

SciTech Connect

Stochastic cooling is the damping of betatron oscillations and momentum spread of a particle beam by a feedback system. In its simplest form, a pickup electrode detects the transverse positions or momenta of particles in a storage ring, and the signal produced is amplified and applied downstream to a kicker. The time delay of the cable and electronics is designed to match the transit time of particles along the arc of the storage ring between the pickup and kicker so that an individual particle receives the amplified version of the signal it produced at the pick-up. If there were only a single particle in the ring, it is obvious that betatron oscillations and momentum offset could be damped. However, in addition to its own signal, a particle receives signals from other beam particles. In the limit of an infinite number of particles, no damping could be achieved; we have Liouville's theorem with constant density of the phase space fluid. For a finite, albeit large number of particles, there remains a residue of the single particle damping which is of practical use in accumulating low phase space density beams of particles such as antiprotons. It was the realization of this fact that led to the invention of stochastic cooling by S. van der Meer in 1968. Since its conception, stochastic cooling has been the subject of much theoretical and experimental work. The earliest experiments were performed at the ISR in 1974, with the subsequent ICE studies firmly establishing the stochastic cooling technique. This work directly led to the design and construction of the Antiproton Accumulator at CERN and the beginnings of p anti p colliding beam physics at the SPS. Experiments in stochastic cooling have been performed at Fermilab in collaboration with LBL, and a design is currently under development for a anti p accumulator for the Tevatron.

Bisognano, J.; Leemann, C.

1982-03-01

310

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

311

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

312

Self-consistent model of magnetospheric ring current and propagating electromagnetic ion cyclotron waves: 2. Wave-induced ring current precipitation and thermal electron heating  

NASA Astrophysics Data System (ADS)

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) currently developing in NASA Marshall Space Flight Center. 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 the simulation can be summarized as follows. First, 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 × 106 (cm2 s sr)-1 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 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. Second, 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. Third, 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 1011 eV/(cm2 s). The Coulomb energy degradation of the RC H+ and O+ ions maximizes at about 1011 eV/(cm2 s) and typically leads to electron energy deposition rates of about 2 × 1010 eV/(cm2 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 of 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.

2007-04-01

313

Electromagnetic Math  

NSDL National Science Digital Library

This book offers an introduction to the electromagnetic spectrum using examples of data from a variety of NASA missions and satellite technologies. The 84 problem sets included allow students to explore the concepts of waves, wavelength, frequency, and speed; the Doppler Shift; light; and the energy carried by photons in various bands of the spectrum. Extensive background information is provided which describes the nature of electromagnetic radiation.

314

Cooling for a rotating anode X-ray tube  

DOEpatents

A method and apparatus for cooling a rotating anode X-ray tube. An electromagnetic motor is provided to rotate an X-ray anode with cooling passages in the anode. These cooling passages are coupled to a cooling structure located adjacent the electromagnetic motor. A liquid metal fills the passages of the cooling structure and electrical power is provided to the motor to rotate the anode and generate a rotating magnetic field which moves the liquid metal through the cooling passages and cooling structure.

Smither, Robert K. (Hinsdale, IL)

1998-01-01

315

An Efficient Algorithm for Shielding Electromagnetic Topological Diagram  

Microsoft Academic Search

An electromagnetic topology method used to analyze interactions between electronic systems and electromagnetic environment is presented. Combining electromagnetic topology model with the graph theory, an efficient algorithm is obtained. The algorithm can find out all the paths which have a lower shielding coefficient than the given threshold K in the shielding electromagnetic topological diagram.

Yongfeng Wang; Chengda Yu; Chaowei Zhang

2010-01-01

316

Corona driven air propulsion for cooling of electronics F. Yang, N.E. Jewell-Larsen, D.L. Brown, K. Pendergrass, D.A. Parker, I.A. Krichtafovitch*, A.V. Mamishev  

E-print Network

Corona driven air propulsion for cooling of electronics F. Yang, N.E. Jewell-Larsen, D.L. Brown, K viscosity in narrow channels reduces the cooling efficiency of the heat sinks. Electrostatic air propulsion by the high intensity electric field at the tip, forming an ion stream between the corona and collector

Mamishev, Alexander

317

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.

Bacca, Sonia

2014-01-01

318

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

319

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

320

Radiative power and electron cooling rates for oxygen in steady-state and transient plasmas at densities beyond the coronal limit  

SciTech Connect

We have developed a time-dependent, collisional-radiative model to calculate radiative power and electron cooling rates for oxygen at intermediate densities (10/sup 16/ cm/sup -3/ less than or equal to n/sub e/ less than or equal to 10/sup 20/ cm/sup -3/) where the usual coronal approximation is not valid. Large differences from coronal values are predicted. The behavior of the steady-state radiative power loss coefficient, L/sub Z, is investigated as the electron density is increased. Generalized power loss coefficients applicable to transient plasmas are derived and applied to ionizing and recombining oxygen plasmas. Time-dependent effects are found to play a large role both in terms of the total radiated power and the net electron energy loss rate. 41 refs., 11 figs.

Keane, C.; Skinner, C.H.

1986-01-01

321

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals  

NASA Technical Reports Server (NTRS)

The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

Hartmann, S. R.; Happer, W.

1974-01-01

322

Electronic refrigeration at the quantum limit.  

PubMed

We demonstrate quantum-limited electronic refrigeration of a metallic island in a low-temperature microcircuit. We show that matching the impedance of the circuit enables refrigeration at a distance, of about 50 microm in our case, through superconducting leads with a cooling power determined by the quantum of thermal conductance. In a reference sample with a mismatched circuit this effect is absent. Our results are consistent with the concept of electromagnetic heat transport. We observe and analyze the crossover between electromagnetic and quasiparticle heat flux in a superconductor. PMID:19519012

Timofeev, Andrey V; Helle, Meri; Meschke, Matthias; Möttönen, Mikko; Pekola, Jukka P

2009-05-22

323

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

324

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

2011-04-15

325

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

326

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

327

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

Microsoft Academic Search

The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) has 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 electronics, is essential for the reliable operation of motors and power electronics. As part of a larger thermal management

C. W. Ayers; J. S. Hsu; K. T. Lowe

328

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

329

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

330

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

331

Electromagnetic Spectrum from QGP Fluid  

E-print Network

We calculate thermal photon and electron pair distribution 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 the source particles on the electromagnetic spectra.

T. Hirano; S. Muroya; M. Namiki

1997-08-29

332

Vehicle Electronics Exponential growth in automotive electronics as  

E-print Network

for Ensuring Electromagnetic Compatibility #12;Using Unintentional Emissions to Anticipate MOSFET and IGBT for designing electronic systems that are guaranteed to comply with their electromagnetic compatibility requirements. #12;Todd Hubing Electromagnetic Compatibility, EM Modeling, Fault Detection. Pierluigi Pisu Fault

Duchowski, Andrew T.

333

Enhanced Conversion of Thermal Electron Bernstein Waves to the Extraordinary Electromagnetic Mode on the National Spherical Torus Experiment (NSTX)  

SciTech Connect

A four-fold increase in the conversion of thermal electron-Bernstein waves (EBW) to the extraordinary mode (X-mode) was measured when the density scale length (L subscript ''n'') was progressively shortened by a local Boron nitride limiter in the scrape-off of an ohmically heated National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng, et al., Proceedings 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The maximum conversion efficiency approached 50% when L subscript ''n'' was reduced to 0.7 cm, in agreement with theoretical predictions that used locally measured L subscript ''n''. Calculations indicate that it is possible to establish L subscript ''n'' < 0.3 cm with a local limiter, a value predicted to attain approximately 100% EBW conversion to the X-mode in support of proposed EBW heating and current drive scenarios.

G. Taylor; P.C. Efthimion; B. Jones; B.P. LeBlanc; J.R. Wilson; J.B. Wilgen; G.L. Bell; T.S. Bigelow; R. Maingi; D.A. Rasmussen; R.W. Harvey; A.P. Smirnov; F. Paoletti; S.A. Sabbagh

2002-10-15

334

Thermal effects on the STAR electromagnetic calorimeter  

SciTech Connect

The STAR detector for the RHIC colliding beam accelerator is under construction at Brookhaven National Laboratory. This detector will consist of a number of subsystems. These include a silicon vertex detector (SVT) for charged particle tracks near the interaction region, a time projection chamber (TPC) for charged particle tracking, an array of plastic scintillation counters (CTB) in a layer around the TPC for triggering on charged particles, a conventional solenoidal magnet, and some additional small triggering detectors along the beam-line. An electromagnetic calorimeter (EMC) is an upgrade to the ``baseline`` detector configuration above. The conventional magnet and numerous electronic channels for the SVT and TPC subsystems will generate a considerable amount of heat during the operation of STAR. However, it is possible that a chiller for the magnet cooling water will not be available during some of the early STAR runs. As a result, the average magnet temperature may vary considerably between winter and summer. This note summarizes calculations and measurements performed to evaluate the effects of an elevated magnet temperature on the performance of the electromagnetic calorimeter.

Fornek, T.; Guarino, V.; Spinka, H.; Underwood, D. [Argonne National Lab., IL (United States). High Energy Physics Div.

1994-07-19

335

Comparison of SAR and induced current densities in adults and children exposed to electromagnetic fields from electronic article surveillance devices  

NASA Astrophysics Data System (ADS)

Electronic article surveillance (EAS) devices are widely used in most stores as anti-theft systems. In this work, the compliance with international guidelines in the human exposure to these devices is analysed by using the finite-difference time-domain (FDTD) method. Two sets of high resolution numerical phantoms of different size (REMCOM/Hershey and Virtual Family), simulating adult and child bodies, are exposed to a 10 MHz pass-by panel-type EAS consisting of two overlapping current-carrying coils. Two different relative positions between the EAS and the body (frontal and lateral exposures), which imply the exposure of different parts of the body at different distances, have been considered. In all cases, induced current densities in tissues of the central nervous system and specific absorption rates (SARs) are calculated to be compared with the limits from the guidelines. Results show that induced current densities are lower in the case of adult models as compared with those of children in both lateral and frontal exposures. Maximum SAR values calculated in lateral exposure are significantly lower than those calculated in frontal exposure, where the EAS-body distance is shorter. Nevertheless, in all studied cases, with an EAS driving current of 4 A rms, maximum induced current and SAR values are below basic restrictions.

Martínez-Búrdalo, M.; Sanchis, A.; Martín, A.; Villar, R.

2010-02-01

336

Particle acceleration through the resonance of high magnetic field and high frequency electromagnetic wave  

E-print Network

electromagnetic wave Hong Liu1,4 , X. T. He2,3 , S. G. Chen2 and W.Y.Zhang2 ¹Graduate School, China Academy a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave

Paris-Sud XI, Université de

337

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

338

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

339

Obtaining high-resolution images of biological macromolecules by using a cryo-electron microscope with a liquid-helium cooled stage.  

PubMed

To obtain high-resolution images of biological macromolecules, a cryo-electron microscope (cryo-EM) is useful to preserve the hydrated state of the molecules. In addition, the cryo-conditions reduce some of the electron radiation damage, although averaging is necessary to obtain the molecular resolution from biological macromolecules. For the averaging, the three reconstruction methods of electron crystallography, helical reconstruction, and single particle analysis facilitate the determination of the atomic models. Here we describe suitable techniques for high-resolution imaging in these three different methods, based on our experiences using cryo-EM with a liquid-helium cooled stage. Irradiation damage by the electron beam is the most serious problem in the structural analysis of a biological specimen, and we clearly show that further reduction of the specimen temperature, from liquid nitrogen to liquid helium temperature, improves the cryo-protection factor by at least two-fold for both glucose-embedded and frozen-hydrated specimens. We review the image processing, and then discuss the future prospects of cryo-EM. PMID:20869255

Mitsuoka, Kaoru

2011-02-01

340

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

Microsoft Academic Search

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

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

2009-01-01

341

Chapter 18. Electromagnetic and Electronic Systems Electromagnetic and Electronic Systems  

E-print Network

to find processes to grow the nanotubes directly on a conductive aluminum substrate. We have successfully. Nanotube-Enhanced Ultracapacitors for Improved Electrical Energy Storage Sponsors MIT Energy Initiative, J. Schindall The purpose of this project is to develop a practical electrical energy storage device

342

Development of a 3D numerical code to calculate the trajectories of the blow off electrons emitted by a vacuum surface discharge: Application to the study of the electromagnetic interference induced on a spacecraft  

NASA Astrophysics Data System (ADS)

A description of the electromagnetic behavior of a satellite subjected to an electric discharge is given using a specially developed numerical code. One of the particularities of vacuum discharges, obtained by irradiation of polymers, is the intense emission of electrons into the spacecraft environment. Electromagnetic radiation, associated with the trajectories of the particles around the spacecraft, is considered as the main source of the interference observed. In the absence of accurate orbital data and realistic ground tests, the assessment of these effects requires numerical simulation of the interaction between this electron source and the spacecraft. This is done by the GEODE particle code which is applied to characteristic configurations in order to estimate the spacecraft response to a discharge, which is simulated from a vacuum discharge model designed in laboratory. The spacecraft response to a current injection is simulated by the ALICE numerical three dimensional code. The comparison between discharge and injection effects, from the results given by the two codes, illustrates the representativity of electromagnetic susceptibility tests and the main parameters for their definition.

Froger, Etienne

1993-05-01

343

Corrosion study of heat exchanger tubes in pressurized water cooled nuclear reactors by conversion electron Mössbauer spectroscopy  

Microsoft Academic Search

57Fe-conversion electron Mössbauer spectroscopy (CEMS) — a sensitive tool to analyze the phase composition of corrosion products\\u000a on the surface of stainless steel — was applied to study real specimens from the Paks Nuclear Power Plant, Hungary. The primary\\u000a circuit side of the heat exchanger tubes was studied on selected samples cut out from the steam generators during regular\\u000a maintenance.

Z. Homonnay; P. Á. Szilágyi; E. Kuzmann; K. Varga; Z. Németh; A. Szabó; K. Radó; J. Schunk; P. Tilky; G. Patek

2007-01-01

344

Bremsstrahlung in the scattering of low-energy electrons by neutral atomic systems. [in atmosphere of sun and cool stars  

NASA Technical Reports Server (NTRS)

By elementary methods, the cross section for electron-atom and electron-molecule bremsstrahlung is computed in the limit when the incident electron energy is much less than Ry. The procedure employs the classical soft-photon emission probability formula for general (h/2pi)(omega), yielding a simple expression for the bremsstrahlung cross section in terms of the total elastic scattering cross section. The validity of the method is discussed, and results are compared with more elaborate and accurate calculations. Comparison is made with ('free-free') opacity calculations for the associated process at the temperature (6300 K) of the solar atmosphere. For chi sub omega = (h/2pi)(omega)/kT = 1, the computed absorption coefficient is within 2, 7, and 12 percent of accurate calculations for scatterings by H, He, and H2, respectively. The general dependence of the opacity on chi sub omega is described well by the simple formula, although the error is larger for higher chi sub omega; it is suggested that the inaccuracy at high frequencies is due to the failure of the soft-photon approximation.

Gould, R. J.

1985-01-01

345

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronics Program) in solid state electronics, quantum electronics, information electronics, control and optimization, and electromagnetic phenomena is presented. Results of the research to date are summarize...

M. Tinkham

1991-01-01

346

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronics Program) in solid state electronics, quantum electronics, information electronics, control and optimization, and electromagnetic phenomena is presented. Results of the research to date are summarize...

M. Tinkham

1987-01-01

347

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronic Program) in solid state electronics, quantum electronics, information electronics control and optimization and electromagnetic phenomenon is presented. Results of the research to date are summarized ...

M. Tinkham

1985-01-01

348

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

349

Electromagnetic generators for power harvesting  

Microsoft Academic Search

The design of electromagnetic generators that can be integrated within shoe soles is described. In this way, parasitic energy expended by a person when walking can be tapped and used to power portable electronic equipment. Designs are based on discrete permanent magnets and copper wire coils, and it is intended to improve performance by applying micro-fabrication technologies. Detailed descriptions of

M. Duffy; D. Carroll

2004-01-01

350

IEEE TRANSACTIONS ON MAGNETICS, VOL. 46, NO. 8, AUGUST 2010 2815 Identification of Equivalent Multipolar Electromagnetic Sources  

E-print Network

of magnetic induction in near field, dedicated to studies of electromagnetic compatibility, are proposed based. Index Terms--Electromagnetic compatibility, identification, magnetic field measurement, multipolar expansion, power electronics, transducers. I. INTRODUCTION F OR electromagnetic compatibility studies

Paris-Sud XI, Université de

351

Vibrational distributions of N2O+(A˜ 2?+) produced by electron impact on jet-cooled N2O  

Microsoft Academic Search

Fluorescence spectra of the N2O+(A˜ 2?+–X˜ 2&Pgr;i) system produced by electron impact on N2O have been studied in the impact energy range of 22–100 eV in order to determine vibrational-state distributions of the N2O+(A˜ 2?+) state. Emission bands from the 00, 21K1, 22K0, 11, 12, and 31 levels have been assigned. The populations of the 11 and 12 levels corrected

Ikuo Tokue; Mikio Kobayashi; Yoshio Ito

1992-01-01

352

Electromagnetic Transport from Microtearing Mode Turbulence  

SciTech Connect

This Letter presents nonlinear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high-{beta} discharge in the National Spherical Torus Experiment. The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free-streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

Guttenfelder, W.; Kaye, S. M.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R. [Princeton Plasma Physics Laboratory, Princeton New Jersey 08543 (United States); Candy, J. [General Atomics, San Diego, California 92186 (United States); Nevins, W. M.; Wang, E. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Yuh, H. [Nova Photonics Inc., Princeton, New Jersey 08540 (United States)

2011-04-15

353

Electromagnetic Transport From Microtearing Mode Turbulence  

SciTech Connect

This Letter presents non-linear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high beta discharge in the National Spherical Torus Experiment (NSTX). The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

Guttenfelder, W; Kaye, S M; Nevins, W M; Wang, E; Bell, R E; Hammett, G W; LeBlanc, B P; Mikkelsen, D R

2011-03-23

354

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

355

Noise and Bandwidth Measurements of Diffusion-Cooled Nb Hot-Electron Bolometer Mixers at Frequencies Above the Superconductive Energy Gap  

NASA Technical Reports Server (NTRS)

Diffusion-cooled Nb hot-electron bolometer (HEB) mixers have the potential to simultaneously achieve high intermediate frequency (IF) bandwidths and low mixer noise temperatures for operation at THz frequencies (above the superconductive gap energy). We have measured the IF signal bandwidth at 630 GHz of Nb devices with lengths L = 0.3, 0.2, and 0.1 micrometer in a quasioptical mixer configuration employing twin-slot antennas. The 3-dB EF bandwidth increased from 1.2 GHz for the 0.3 gm long device to 9.2 GHz for the 0.1 gm long device. These results demonstrate the expected 1/L squared dependence of the IF bandwidth at submillimeter wave frequencies for the first time, as well as the largest EF bandwidth obtained to date. For the 0.1 gm device, which had the largest bandwidth, the double sideband (DSB) noise temperature of the receiver was 320-470 K at 630 GHz with an absorbed LO power of 35 nW, estimated using the isothermal method. A version of this mixer with the antenna length scaled for operation at 2.5 THz has also been tested. A DSB receiver noise temperature of 1800 plus or minus 100 K was achieved, which is about 1,000 K lower than our previously reported results. These results demonstrate that large EF bandwidth and low-noise operation of a diffusion-cooled HEB mixer is possible at THz frequencies with the same device geometry.

Wyss, R. A.; Karasik, B. S.; McGrath, W. R.; Bumble, B.; LeDuc, H.

1999-01-01

356

IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 9, No. 2, JUNE 1999 4217 New Results for NbN Phonon-CooledHot Electron BolometricMixers Above 1 THz  

E-print Network

N Phonon-CooledHot Electron BolometricMixers Above 1 THz E. Gerecht, C. F. Musante, H. Jian, and K in terms of DSB receivernoise temperature(2,800Kat 1.56THz). TheLO sourcefor thesemix- ers is a gas laser. Receivernoisetemperaturesbelow1THz are typically450-600K and areexpectedto graduallyapproachthese levelsabove 1THz aswell. Nb

Massachusetts at Lowell, University of

357

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

358

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

359

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

360

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. 12 figs.

McEwan, T.E.

1996-11-19

361

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

362

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

363

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

364

ATHENA X-IFU detector cooling chain  

NASA Astrophysics Data System (ADS)

The TES (Transition Edge Sensors) micro-calorimeter detector technology in the X-IFU instrument for ATHENA (Astrophyics of the Hot and Energetic universe - Europe's next generation X-ray observatory ATHENA) will require cooling down to 50 mK, and a stable and quiet Electro-Magnetic and micro-vibrations environment. In order to achieve this temperature and environment, a cooling chain integrated in a compact cryostat with an optimized electromagnetic environment has to be developed. Critical technology developments are covered, such as mechanical cryocoolers, support structures, radiative and EMC shields, micro-vibrations reduction, and others.

Branco, M. B. C.; Charles, I.; Butterworth, J.

2014-07-01

365

Energy efficient liquid cooling  

Microsoft Academic Search

The theme of this paper is an investigation of the hydrodynamic performance of liquid pumps for electronics cooling applications, considered in conjunction with a range of primary heat exchangers. Pressure-flow characteristics of a set of geometrically- similar, miniature-scale centrifugal pumps are measured, and reductions in hydrodynamic efficiency are seen to occur below a critical Reynolds number. Six primary heat exchangers

Jeff Punch

2008-01-01

366

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

367

Electromagnetic compatibility  

Microsoft Academic Search

The ever-increasing number of applications of electrical and electronic equipment, is also giving rise to an increasing number of disappointments. This is because different pieces of equipment in use are found to interfere with each other. To mention some examples: the digital circuits in a home computer may cause interference in television reception; diathermy equipment produces a loud hum from

J. J. Goedbloed

1987-01-01

368

Particle acceleration by electromagnetic waves.  

PubMed

We consider the symmetry in the interaction of photons and electrons, which has led to a common description of electron and photon accelerations; effects such as photon Landau damping arise naturally from such a treatment. Intense electromagnetic waves can act as a photon mirror to charged particles. The subsequent acceleration is equivalent to the photon pulse accelerating electrons. During the interaction or reflection process, the charged particle can emit bursts of radiation similar to the radiation emitted from the particles during wave breaking of plasma waves. PMID:18218605

Bingham, R

2008-05-28

369

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

370

Ventilative cooling  

E-print Network

This thesis evaluates the performance of daytime and nighttime passive ventilation cooling strategies for Beijing, Shanghai and Tokyo. A new simulation method for cross-ventilated wind driven airflow is presented . This ...

Graça, Guilherme Carrilho da, 1972-

1999-01-01

371

Cool Vest  

NASA Technical Reports Server (NTRS)

ILC, Dover Division's lightweight cooling garment, called Cool Vest was designed to eliminate the harmful effects of heat stress; increases tolerance time in hot environments by almost 300 percent. Made of urethane-coated nylon used in Apollo, it works to keep the body cool, circulating chilled water throughout the lining by means of a small battery-powered pump. A pocket houses the pump, battery and the coolant which can be ice or a frozen gel, a valve control allows temperature regulation. One version is self-contained and portable for unrestrained movement, another has an umbilical line attached to an external source of coolant, such as standard tap water, when extended mobility is not required. It is reported from customers that the Cool Vest pays for itself in increased productivity in very high temperatures.

1982-01-01

372

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

373

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

374

Development of a 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 the wiggler field and operate at low current densities by virtue of their placement away from the midplane. We describe here the design approach used and test data from a 7-period wiggler prototype that includes curved pole tips to provide wiggle-plane focusing. 7 refs.

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

1987-01-01

375

IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. QE-20, NO. 6 , JUNE 1984 625 mixture at 7 torr. If the flow is insufficient, then the cooling  

E-print Network

. If the flow is insufficient, then the cooling system cannot remove enoughheat to compensateforthat which is being transferred into the tube through radiation and convectionandno CW lasing occurs. However, at high controls the outlet temperature of the cooling gas when a constantflowrate is maintained. Theresults

Rocca, Jorge J.

376

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

377

Investigation of electromagnetic welding  

E-print Network

We propose several methodologies to study and optimize the electromagnetic process for Electromagnetic Forming (EMF) and Welding (EMW), thereby lowering the necessary process energy up to a factor of three and lengthening ...

Pressl, Daniel G. (Daniel Gerd)

2009-01-01

378

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This web site contains materials about all parts of the electromagnetic spectrum. It describes each space telescope that NASA has launched as well as its observing range in the electromagnetic spectrum.

Astrophysics, Laboratory F.

2004-11-17

379

Electromagnetic Field Exposure Dosimeter.  

National Technical Information Service (NTIS)

The growing concern about adverse health effects caused by electromagnetic radiation prompted the ideas for this dosimeter. Data have been presented that ink prolonged exposure to electromagnetic radiation from power lines to leukemia and some types of ca...

A. C. Feaga, M. P. Hilliard, R. Link

1994-01-01

380

Shape optimization of electromagnet  

Microsoft Academic Search

The paper deals with finding the optimal shape of the electromagnet by changing skew keeper and skew pole shoe of the electromagnet so as to obtain maximum tensile force. The solution used numerical methods, especially the program COMSOL.

S. Zajaczek; L. Skr?iva?nek; L. Iva?nek

2010-01-01

381

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

382

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

383

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

384

Electromagnetic Interference (Emi)  

Microsoft Academic Search

\\u000a Electric and magnetic signals originating outside of a defibrillator may affect its operation, a phenomenon known as electromagnetic\\u000a interference (EMI). EMI usually refers to interference from environmental electromagnetic instrumentation and should be distinguished\\u000a from other sources of electromagnetic noise causing ICD malfunction (Table 1). Signals most likely to penetrate and affect\\u000a pacemakers and ICDs are electromagnetic waves or signals at

Mike Hardage; Philip D. Henry

385

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

386

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

387

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  

NASA Astrophysics Data System (ADS)

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.

2012-05-01

388

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

389

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

390

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

391

An electromagnetic actuated microvalve fabricated on a single wafer  

NASA Astrophysics Data System (ADS)

Microvalves are essential components of the miniaturization of the fluidic systems to control of fluid flow in a variety of applications as diverse as chemical analysis systems, micro-fuel cells, and integrated fluidic channel arrangements for electronic cooling. Using microvalves, these systems offer important advantages: they can operate using small sample volumes and provide rapid response time. This PhD dissertation presents the world first electromagnetically actuated microvalve fabricated on a single wafer with CMOS compatibility. In this dissertation, the design, fabrication, and testing results of two different types of electromagnetic microvalves are presented: the on/off microvalve and the bistable microvalve with latching mechanism. The microvalves operate with power consumption of less than 1.5 W and can control the volume flow rate of DI water, or a 50% diluted methanol solution in the range 1--50 muL/min. The leaking rate of the on/off microvalve is the order of 30 nL/min. The microvalve demonstrated a response time for latching of 10 ms in water and 0.2 ms in air. This work has resulted in a US patent, application no. 10/699,210. Other inventions that have been developed as a result of this research are bidirectional, and bistable-bidirectional microactuators with latching mechanism, that can be utilized for optical switch, RF relay, micro mirror, nano indenter, or nano printings.

Sutanto Bintoro, Jemmy

392

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

393

Research on the non-linear temperature field of molten metal shaped by an electromagnetic field in DS processing  

Microsoft Academic Search

A new directional solidification (DS) technique, combining electromagnetic shaping with liquid metal cooling, is established to confine and shape liquid metal by an electromagnetic field without the mold and carry out DS with a high-temperature gradient. The motion of the sample, heat radiation, and especially the material-property difference between the solid and the liquid, are considered for electromagnetic heating. Thereafter,

Jinshan Li; Qitang Hao; Shuangming Li; Hongchao Kou; Jianguo Li; Hengzhi Fu

2003-01-01

394

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

395

Cooling Vest  

NASA Technical Reports Server (NTRS)

Because quadriplegics are unable to perspire below the level of spinal injury, they cannot tolerate heat stress. A cooling vest developed by Ames Research Center and Upjohn Company allows them to participate in outdoor activities. The vest is an adaptation of Ames technology for thermal control garments used to remove excess body heat of astronauts. The vest consists of a series of corrugated channels through which cooled water circulates. Its two outer layers are urethane coated nylon, and there is an inner layer which incorporates the corrugated channels. It can be worn as a backpack or affixed to a wheelchair. The unit includes a rechargeable battery, mini-pump, two quart reservoir and heat sink to cool the water.

1983-01-01

396

Electromagnetic space-time crystals. III. Dispersion relations for partial solutions  

E-print Network

Partial solutions of the Dirac equation describing an electron motion in electromagnetic crystals created by plane waves with linear and circular polarizations are treated. It is shown that the electromagnetic crystal formed by circularly polarized waves possesses the spin birefringence.

G. N. Borzdov

2014-10-21

397

A 3.5 Tesla Laboratory Electromagnet  

NASA Astrophysics Data System (ADS)

We report the design and construction of a laboratory electromagnet utilizing HTS coils in an iron yoke with a magnetic flux density of 3.5 Tesla in a 50-mm air-gap. With continuing improvement in the performance of HTS "BSCCO" wire, several niche HTS magnet applications have become viable at current wire prices. In this instance, the HTS conductor confers the advantages of high field strength combined with compact size and energy efficiency, in an electromagnet of a format suitable for many materials' characterization techniques, such as vibrating-sample magnetometry, for which the current magnet will be employed. The magnet employs four HTS coils, with a total of 1.6 km of BSCCO wire, which are conduction cooled using a single-stage Gifford-McMahon cryocooler, delivering approximately 25 W of cooling power at the target 35 K operating temperature; HTS current leads are utilized to minimize heat leak to the cryogenic environment.

Pooke, D. M.; Chamritski, V.; Gibson, S.; Fee, M.; King, T.; Staines, M. P.; Flower, N. E.; Buckley, R. G.

2004-06-01

398

Electromagnetically driven dwarf tornados in turbulent convection  

NASA Astrophysics Data System (ADS)

Motivated by the concept of interdependency of turbulent flow and electromagnetic fields inside the spiraling galaxies, we explored the possibilities of generating a localized Lorentz force that will produce a three-dimensional swirling flow in weakly conductive fluids. Multiple vortical flow patterns were generated by combining arrays of permanent magnets and electrodes with supplied dc current. This concept was numerically simulated and applied to affect natural convection flow, turbulence, and heat transfer inside a rectangular enclosure heated from below and cooled from above over a range of Rayleigh numbers (104<=Ra<=5×109). The large-eddy simulations revealed that for low- and intermediate-values of Ra, the heat transfer was increased more than five times when an electromagnetic forcing was activated. In contrast to the generally accepted view that electromagnetic forcing will suppress velocity fluctuations and will increase anisotropy of turbulence, we demonstrated that localized forcing can enhance turbulence isotropy of thermal convection compared to its neutral state.

Kenjereš, Saša

2011-01-01

399

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

400

Physical mechanism of ion entrainment by the electron space charge in acceleration by the gradients of static magnetic and of electromagnetic fields  

Microsoft Academic Search

A theory of the physical mechanism of ion entrainment by accelerated electrons is presented. It is shown that under the influence of these fields the electrons describe helixes whose diameter and pitch vary along the axis of motion as a function of the difference between the cyclotron frequency and the frequency of the applied hf field. The space charge thus

Rene Bardet; Terenzio Consoli; Richard Geller

1965-01-01

401

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

402

Electromagnetic processes in the atmosphere of pulsars  

NASA Technical Reports Server (NTRS)

The work consists of two parts. The first deals with the fine structure of radio pulses. Based on kinetic theory, processes occurring in the plasma shell of a pulsar when external electromagnetic radiation is present are investigated. It is shown that electromagnetic waves cause electrons to drift relative to ions, and initiate longitudinal oscillations. A dispersion equation describing the longitudinal oscillations in magnetized plasma is derived. Conditions for excitation of oscillations are found. Correlation functions of electron density are calculated, along with the coefficients of electromagnetic wave scattering. It is shown that variations in the amplitude of pulsar pulses are associated with scintillations caused by fluctuations in the plasma electron density. The second part of the study presents a mechanism for the radio emission of pulsars. The model of a rotating and a pulsating star, a neutron star with dipolar or more complex magnetic field, is examined.

Yukhimuk, A. K.

1974-01-01

403

Radar electronic warfare  

Microsoft Academic Search

An overview of radar and electronic warfare is given. Definitions, common terms, and principles of radar and electronic warfare, and simple analyses of interactions between radar systems and electronic countermeasures (ECM) are presented. Electronic counter-countermeasure and electronic support measures are discussed. Background material in mathematics, electromagnetics, and probability necessary for an understanding of radar and electronic warfare is given and

August Golden Jr.

1987-01-01

404

An overview on packaging of microwave electronic devices operating in a cryogenic environment  

NASA Astrophysics Data System (ADS)

Microwave cryogenic electronics design involves not only electrical, RF and electromagnetically considerations but also mechanical and assembly aspects. Details heavily influence the final device performances. Radio astronomical science often requires cooling down front end parts of the receivers in order to increase the system sensitivity. In this paper we will introduce the device working environment, crucial aspects of the housing, and we will describe a variety of possible solutions.

Cremonini, Andrea; Mariotti, Sergio; Roda, Juri

2012-10-01

405

ELECTRICAL ENGINEERING at PORTLAND STATE UNIVERSITY Electrical Engineering deals with the study and application of electricity, electronics and electromagnetism. It covers a range of  

E-print Network

ELECTRICAL ENGINEERING at PORTLAND STATE UNIVERSITY Electrical Engineering deals with the study, electronics, telecommunications, etc. Electrical Engineers are typically concerned with using electricity to trans- mit energy and also to process information. Students must apply to the Electrical Engineering (EE

Bertini, Robert L.

406

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

407

Phenomenology of the deuteron electromagnetic form factors  

SciTech Connect

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. 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.

David Abbott; Abdellah Ahmidouch; H. Anklin; J. Arvieux; James P. Ball; Shelton Beedoe; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; K. Dow; Jean-Eric Ducret; Jim Dunne; Lars Ewell; L. Eyraud; C. Furget; Michel Garcon; Ron Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; A. Honegger; J. Jourdan; Serge Kox; Gerfried Kumbartzki; L. Lu; Allison Lung; Pete Markowitz; Justin McIntyre; David Meekins; F. Merchez; Joseph Mitchell; R. Mohring; S. Mtingwa; H. Mrktchyan; D. Pitz; Liming Qin; Ronald Ransome; J.-S. R'eal; Philip Roos; Paul Rutt; Reyad Sawafta; Stepan Stepanyan; Raphael Tieulent; E. Tomasi-Gustafsson; William Turchinetz; K. Vansyoc; J. Volmer; E. Voutier; Claude Williamson; Stephen Wood; Chen Yan; Jianguo Zhao; W. Zhao

2000-04-01

408

Phenomenology of the deuteron electromagnetic form factors  

SciTech Connect

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. 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.

David Abbott; Abdellah Ahmidouch; H. Anklin; J. Arvieux; James P. Ball; Shelton Beedoe; Elizabeth Beise; Louis Bimbot; Werner Boeglin; Herbert Breuer; Roger Carlini; Nicholas Chant; Samuel Danagoulian; K. Dow; Jean-Eric Ducret; Jim Dunne; Lars Ewell; L. Eyraud; C. Furget; Michel Garcon; Ron Gilman; Charles Glashausser; Paul Gueye; Kenneth Gustafsson; Kawtar Hafidi; A. Honegger; J. Jourdan; Serge Kox; Gerfried Kumbartzki; L. Lu; Allison Lung; Pete Markowitz; Justin McIntyre; David Meekins; F. Merchez; Joseph Mitchell; R. Mohring; S. Mtingwa; H. Mrktchyan; D. Pitz; Liming Qin; Ronald Ransome; J.-S. R'eal; Philip Roos; Paul Rutt; Reyad Sawafta; Stepan Stepanyan; Raphael Tieulent; E. Tomasi-Gustafsson; William Turchinetz; K. Vansyoc; J. Volmer; E. Voutier; Claude Williamson; Stephen Wood; Chen Yan; Jianguo Zhao; W. Zhao

2000-02-25

409

Compton Sources of Electromagnetic Radiation  

SciTech Connect

When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

Geoffrey Krafft,Gerd Priebe

2011-01-01

410

Cool It!  

NSDL National Science Digital Library

In this fun hands-on activity, learners use simple materials to investigate evaporation. How can the evaporation of water on a hot day be used to cool an object? Find out the experimental way! The activity is based on an episode of Cyberchase called "Digit's B-Day Surprise" and was developed to capture kids' interest in math using the appeal of the popular PBS series.

Wnet; Title Entertainment, Inc.

2009-01-01

411

Global cooling?  

PubMed

The world's inhabitants, including Scientists, live primarily in the Northern Hemisphere. It is quite natural to be concerned about events that occur close to home and neglect faraway events. Hence, it is not surprising that so little attention has been given to the Southern Hemisphere. Evidence for global cooling has been based, in large part, on a severe cooling trend at high northern latitudes. This article points out that the Northern Hemisphere cooling trend appears to be out of phase with a warming trend at high latitudes in the Southern Hemisphere. The data are scanty. We cannot be sure that these temperature fluctuations are be not the result of natural causes. How it seems most likely that human activity has already significantly perturbed the atmospheric weather system. The effect of particulate matter pollution should be most severe in the highly populated and industrialized Northern Hemisphere. Because of the rapid diffusion of CO(2) molecules within the atmosphere, both hemispheres will be subject to warming due to the atmospheric (greenhouse) effect as the CO(2) content of the atmosphere builds up from the combustion of fossil fuels. Because of the differential effects of the two major sources of atmospheric pollution, the CO(2) greenhouse effect warming trend should first become evident in the Southern Hemisphere. The socioeconomic and political consequences of climate change are profound. We need an early warning system such as would be provided by a more intensive international world weather watch, particularly at high northern and southern latitudes. PMID:17841800

Damon, P E; Kunen, S M

1976-08-01

412

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

413

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

414

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.

Research Experience for Teachers (RET) Program, Center of Advancement of Engineering Fibers and Films,

415

CO$_2$ cooling experience (LHCb)  

E-print Network

The thermal control system of the LHCb VErtex LOcator (VELO) is a two-phase C0$_2$ cooling system based on the 2-Phase Accumulator Controlled Loop (2PACL) method. Liquid carbon dioxide is mechanically pumped in a closed loop, chilled by a water-cooled freon chiller and evaporated in the VELO detector. The main goal of the system is the permanent cooling of the VELO silicon sensors and of the heat producing front-end electronics inside a vacuum environment. This paper describes the design and the performance of the system. First results obtained during commissioning are also presented.

Van Lysebetten, Ann; Verlaat, Bart

2007-01-01

416

Color-preserving daytime radiative cooling Linxiao Zhu, Aaswath Raman, and Shanhui Fan  

E-print Network

Color-preserving daytime radiative cooling Linxiao Zhu, Aaswath Raman, and Shanhui Fan Citation://apl.aip.org/features/most_downloaded Information for Authors: http://apl.aip.org/authors #12;Color-preserving daytime radiative cooling Linxiao Zhu-preserving daytime radiative cooling. The Earth's atmosphere has a transparency window for electromagnetic waves

Fan, Shanhui

417

Cryogenic Heat Pipe for Cooling High Temperature Superconductors with Application to  

E-print Network

Cryogenic Heat Pipe for Cooling High Temperature Superconductors with Application;#12;Cryogenic Heat Pipe for Cooling High Temperature Superconductors with Application to Electromagnetic at the Massachusetts Institute of Technology. 3 #12;#12;5 Cryogenic Heat Pipe for Cooling High Temperature

418

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

419

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.

420

Susceptibility of Civilian GPS Receivers to Electromagnetic Radiation  

Microsoft Academic Search

Civilian handheld global positioning system receivers were tested for their susceptibility against radiated electromagnetic disturbances of different characteristics and field levels. This susceptibility data were compared to the existing electromagnetic compatibility (EMC) immunity requirements for electronic devices. Some of the receivers were disrupted by continues waves at in- as well as out-of-band frequencies, at field levels far below the existing

D. Mansson; R. Thottappillil; T. Nilsson; O. Lunden; M. Backstrom

2008-01-01

421

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

422

Polarization of high energy gamma quanta in strong electromagnetic fields  

Microsoft Academic Search

The behaviour of refractive indices for gamma quanta with different polarization in strong electromagnetic fields has been considered by the operator quasiclassical method. Birefringence in uniform electromagnetic fields and in interplanar electric fields in single crystals has been analyzed. Possibilities to use this effect in obtaining linearly and circularly polarized gamma quanta as well as longitudinally polarized conversion electrons with

A. M. Frolov; V. A. Maisheev; V. L. Mikhaljov

1987-01-01

423

Radiated and nonradiated electromagnetic fields in an FEL amplifier  

Microsoft Academic Search

For a free-electron laser (FEL) amplifier model, which incorporates not only potential but also rotational nonradiated electromagnetic fields, we study the repercussions of account for those fields on the beam–microwave interaction. Equations of excitation for the radiated and nonradiated parts of the driven electromagnetic field are derived. A new analytical technique of approximate integration of the nonradiated part along the

V. A. Goryashko; K. Ilyenko; A. N. Opanasenko

2010-01-01

424

Radiated and nonradiated electromagnetic fields in an FEL amplifier  

Microsoft Academic Search

For a free-electron laser (FEL) amplifier model, which incorporates not only potential but also rotational nonradiated electromagnetic fields, we study the repercussions of account for those fields on the beam-microwave interaction. Equations of excitation for the radiated and nonradiated parts of the driven electromagnetic field are derived. A new analytical technique of approximate integration of the nonradiated part along the

V. A. Goryashko; K. Ilyenko; A. N. Opanasenko

2010-01-01

425

Drift effects on electromagnetic geodesic acoustic modes  

E-print Network

A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the $f\\sim 40$ kHz oscillation observed in TCABR [Yu. K. Kuznetsov $\\textit{et al.}$, Nucl. Fusion $\\bf{52}$, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is $\\lambda_r\\sim 25$ cm, i. e., an order of magnitude higher than the usual value for zonal flows (ZFs).

Sgalla, Reneé J F

2014-01-01

426

Ultrarelativistic electromagnetic pulses in plasmas  

NASA Technical Reports Server (NTRS)

The physical processes of a linearly polarized electromagnetic pulse of highly relativistic amplitude in an underdense plasma accelerating particles to very high energies are studied through computer simulation. An electron-positron plasma is considered first. The maximum momenta achieved scale as the square of the wave amplitude. This acceleration stops when the bulk of the wave energy is converted to particle energy. The pulse leaves behind as a wake a vacuum region whose length scales as the amplitude of the wave. The results can be explained in terms of a snow plow or piston-like action of the radiation on the plasma. When a mass ratio other than unity is chosen and electrostatic effects begin to play a role, first the ion energy increases faster than the electron energy and then the electron energy catches up later, eventually reaching the same value.

Ashour-Abdalla, M.; Leboeuf, J. N.; Tajima, T.; Dawson, J. M.; Kennel, C. F.

1981-01-01

427

Electromagnetic WavesElectromagnetic Waves In this chapter we will review selected properties of electromagnetic waves since  

E-print Network

of electromagnetic waves since radar involves the transmission, propagation and scattering of EM waves by various dielectric materials. Electric Field--charged bodies create an electric field which in turn constitutes material. This movement of electrons constitutes an electric current. Hence magnetic fields are associated

Rutledge, Steven

428

Analysis and utilization of Joule heating in an electromagnet integrated microfluidic device for biological applications  

Microsoft Academic Search

Joule heating in the electromagnetic cell sorting system is problematic. Our micro-device was fabricated for the rapid separation by high magnetic field gradients of electromagnet and dissipates the Joule heat energy that causes unnecessary heat-up in the device. By using a cooling channel embedded in microfluidic channel, Joule heat can be reduced to dissipate thermal energy to an active area

Suk-Heung Song; Bong-Seop Kwak; Hyo-Il Jung

2009-01-01

429

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

430

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

431

Excitation of high-frequency electromagnetic waves by energetic electrons with a loss cone distribution in a field-aligned potential drop  

NASA Technical Reports Server (NTRS)

The electron cyclotron maser instability (CMI) driven by momentum space anisotropy (df/dp (sub perpendicular) greater than 0) has been invoked to explain many aspects, such as the modes of propagation, harmonic emissions, and the source characteristics of the auroral kilometric radiation (AKR). Recent satellite observations of AKR sources indicate that the source regions are often imbedded within the auroral acceleration region characterized by the presence of a field-aligned potential drop. In this paper we investigate the excitation of the fundamental extraordinary mode radiation due to the accelerated electrons. The momentum space distribution of these energetic electrons is modeled by a realistic upward loss cone as modified by the presence of a parallel potential drop below the observation point. On the basis of linear growth rate calculations we present the emission characteristics, such as the frequency spectrum and the emission angular distribution as functions of the plasma parameters. We will discuss the implication of our results on the generation of the AKR from the edges of the auroral density cavities.

Fung, Shing F.; Vinas, Adolfo F.

1994-01-01

432

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

433

Electromagnetic compatibility overview  

NASA Technical Reports Server (NTRS)

An assessment of the electromagnetic compatibility impact of the Satellite Power System is discussed. The discussion is divided into two parts: determination of the emission expected from SPS including their spatial and spectral distributions, and evaluation of the impact of such emissions on electromagnetic systems including considerations of means for mitigating effects.

Davis, K. C.

1980-01-01

434

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.

435

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.

436

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

437

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

438

Electrode patterns in arc discharge simulations: effect of anode cooling  

NASA Astrophysics Data System (ADS)

Self-organized electrode patterns are often observed experimentally in diverse types of electrical discharges, including atmospheric-pressure electric arcs, but rarely captured in general-purpose computational plasma dynamics simulations. Time-dependent three-dimensional thermodynamic non-equilibrium (two-temperature) simulations reveal the spontaneous formation of self-organized anode attachment spot patterns in the free-burning arc, a canonical direct-current (dc) discharge with an axisymmetric electrode configuration and the absence of external forcing. The simulations are based on a monolithic fluid-electromagnetic plasma flow model numerically implemented within a second-order-accurate in space and time variational multiscale finite element framework. Simulation results show the gradual emergence of spot patterns with increasing levels of anode cooling: from a single diffuse spot for low cooling levels to the eventual coverage of the anode region by small spots for intense cooling. The characteristics of the patterns, such as the number, size and location of the spots, markedly depend on the imposed total current. Furthermore, the patterns transition from steady to dynamic with decreasing total current for high cooling levels. The pattern dynamics show the formation of new spots by the splitting of old ones occurring in the center of the plasma, as well as the movement and eventual extinction of spots at the plasma boundaries. The different types of anode patterns (from diffuse to self-organized spots) have a significant effect on the total voltage drop across the plasma column, but a minor effect on other plasma characteristics away from the anode region. The results indicate that thermal instability together with equilibration between heavy-species and electron energy have a dominant role in the formation of anode patterns in arc discharges.

Trelles, Juan Pablo

2014-10-01

439

Relativistic particle motion in nonuniform electromagnetic waves  

NASA Technical Reports Server (NTRS)

It is shown that a charged particle moving in a strong nonuniform electromagnetic wave suffers a net acceleration in the direction of the negative intensity gradient of the wave. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities can result.

Schmidt, G.; Wilcox, T.

1973-01-01

440

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

441

Extension of Chaos Anticontrol Applied to the Improvement of Switch-Mode Power Supply Electromagnetic Compatibility  

E-print Network

Electromagnetic Compatibility Cristina MOREL, Marc BOURCERIE, and Franc¸ois CHAPEAU-BLONDEAU Laboratoire d method improv- ing switch-mode power supplies electromagnetic compatibility (spectral peaks compliance for power electronic circuit designers. Such interfer- ence create significant electromagnetic compatibility

Chapeau-Blondeau, François

442

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

443

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

444

Electromagnetic conic sections Tevian Draya)  

E-print Network

Electromagnetic conic sections Tevian Draya) Department of Mathematics, Oregon State University electromagnetic conic sections. We then give a necessary and sufficient condition for a given vector field

445

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

446

Basic Discoveries in Electromagnetic Field Visualization  

NASA Astrophysics Data System (ADS)

Basic discoveries in the electromagnetic field visualization are presented, mentioning the late Dr. A. Tonomura's significant achievements in this field. First, the discovery of the electron biprism interferences by G. Möllenstedt and his colleagues was noted. Having studied Möllenstedt's interference experiments, A. Tonomura and his colleagues have extended the electron holography system to clearly prove the physical reality of vector potentials, the so-called Aharonov-Bohm effect. They also succeeded in observing the dynamic motions of magnetic flux quanta (fluxons) in a superconducting Nb film. In a joint research with A. Tonomura, we succeeded in visualizing a fluxon pinned by an insulating particle in a high-Tc Y-Ba-Cu-O superconductor by combining electron holography and scanning ion microscopy. As the study of a scalar potential, the visualization of the orbits of electron-induced secondary electrons around positively charged biological specimens was noted. Finally, although the electromagnetic field analysis using electron holography on the basis of Maxwell's equations seems to be promising, it is pointed out that there have been some controversies on the interpretation and treatment of electromagnetic field.

Shindo, Daisuke

2014-01-01

447

Electromagnetic interference analysis of magnetic resistance sensors inside a projectile under complex electromagnetic environments  

NASA Astrophysics Data System (ADS)

Accurate measurement of angular motion has long been recognized as a daunting task. In recent years the measurement of projectiles utilizing magnetic resistance sensors has become a hot research field. Electromagnetic interference on attitude measurement cannot be ignored in complex electromagnetic environments such as battlefield conditions. In this paper, the influence and function pattern of electromagnetic interference on the measuring performance are theoretically analyzed, and the shielding effectiveness (SE) simulation of projectile is conducted via software Computer Simulation Technology (CST). Considering the specific tests, the intensity of the influence is judged. The simulation indicates that the battlefield's complex electromagnetic environment influences the environment inside the projectile, especially its electronic components and capability. The research results can provide important theoretical support on the errors compensation and precision improvement of the projectile attitude measurement with Magnetic Resistance sensor.

Guo, Qingwei; Gao, Min; Lu, Zhicai; Yang, Peijie

2013-03-01

448

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.

449

Parametrically shielding electromagnetic fields by nonlinear metamaterials.  

PubMed

An analytical theory is developed for parametric interactions in metamaterial multilayer structures with simultaneous nonlinear electronic and magnetic responses and with a near-zero refractive index. We demonstrate theoretically that electromagnetic fields of certain frequencies can be parametrically shielded by a nonlinear left-handed material slab, where the permittivity and permeability are both negative. The skin depth is tunable, and even in the absence of material absorption, can be much less than the wavelength of the electromagnetic field being shielded. This exotic behavior is a consequence of the intricate nonlinear response in the left-handed materials and vanishing optical refractive index at the pump frequency. PMID:18352472

Feng, Simin; Halterman, Klaus

2008-02-15

450

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

451

Electromagnetic Calorimeter for Hades Experiment  

NASA Astrophysics Data System (ADS)

Electromagnetic calorimeter (ECAL) is being developed to complement the dilepton spectrometer HADES currently operating at GSI Darmstadt, Germany. ECAL will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 A GeV on the beam of future accelerator SIS100@FAIR. The calorimeter will also improve the electron-hadron separation and will as well be used for the detection of photons from strange resonances in elementary and heavy ion reactions. Calorimeter modules constructed of lead glass Cherenkov counter, photomultiplier, HV divider and optical fiber are described in the detail. Two prototypes of novel front-end electronics based on TRB3 are presented. A dedicated LED based system being developed to monitor the stability of the calorimeter during beamtime is introduced as well.

Kugler, A.; Blume, C.; Czyžycki, W.; Epple, E.; Fabbietti, L.; Galatyuk, T.; Golubeva, M.; Guber, F.; Hlavá?, S.; Ivashkin, A.; Kajetanowic, M.; Kardan, B.; Koenig, W.; Lapidus, K.; Lisowski, E.; Pietraszko, J.; Reshetin, A.; Rost, A.; Salabura, P.; Sobolev, Y. G.; Svoboda, O.; Tlusty, P.; Traxler, M.

2014-06-01

452

The Electromagnetic Spectrum  

NSDL National Science Digital Library

This interactive, online module reviews the basics of the the electromagnetic spectrum and makes the connection between radiation theory and the images we get from weather satellites. Students will learn about: the electromagnetic spectrum; electromagnetic waves; the electromagnetic spectrum and radiation theory; and how satellite radiometers "see" different sections of the spectrum. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

453

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

454

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