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1

Electron cooling  

NASA Astrophysics Data System (ADS)

The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities—storage rings and traps being in operation or under development—is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler—recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

Meshkov, I.; Sidorin, A.

2004-10-01

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

ElectronicsCooling  

NSDL National Science Digital Library

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

2002-01-01

4

Coherent Electron Cooling  

SciTech Connect

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

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

2009-03-20

5

Coherent electron cooling  

SciTech Connect

Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

Litvinenko,V.

2009-05-04

6

ELECTRON COOLING OF RHIC.  

SciTech Connect

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

BEN-ZVI, I.; LITVINENKO, V.; BARTON, D.; ET AL.

2005-05-16

7

ELECTRON COOLING FOR RHIC.  

SciTech Connect

We introduce plans for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This project has a number of new features as electron coolers go: It will cool 100 GeV/nucleon ions with 50 MeV electrons; it will be the first attempt to cool a collider at storage-energy; and it will be the first cooler to use a bunched beam and a linear accelerator as the electron source. The linac will be superconducting with energy recovery. The electron source will be based on a photocathode gun. The project is carried out by the Collider-Accelerator Department at BNL in collaboration with the Budker Institute of Nuclear Physics.

BEN-ZVI,I.; AHRENS,L.; BRENNAN,M.; HARRISON,M.; KEWISCH,J.; MACKAY,W.; PEGGS,S.; ROSER,T.; SATOGATA,T.; TRBOJEVIC,D.; YAKIMENKO,V.

2001-06-18

8

Electron Cooling of RHIC  

SciTech Connect

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

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

2005-05-16

9

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

10

Electromagnetic electron temperature anisotropy instabilities  

NASA Technical Reports Server (NTRS)

This paper considers electromagnetic Vlasov instabilities driven by electron temperature anisotropies in a homogeneous, nonrelativistic magnetized plasma. Numerical solutions of the full linear dispersion equation for bi-Maxwellian distribution functions and instabilities propagating parallel to the magnetic field are presented. Parametric dependences of the maximum growth rates of the electron fire hose and whistler anisotropy instabilities are given.

Gary, S. P.; Madland, C. D.

1985-01-01

11

Antiproton and electron optics for electron cooling.  

National Technical Information Service (NTIS)

Optical issues for electron cooling in the Recycler are discussed. An optimal value of the antiproton beta-function depends on the cooling purposes (longitudinal or transverse), on the antiproton emittances and the energy spread. A proposal is suggested f...

A. V. Burov

2000-01-01

12

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

13

Power electronics cooling apparatus  

SciTech Connect

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, P.A.; Lindberg, F.A.; Garcen, W.

2000-01-18

14

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

15

Cooling Shelf For Electronic Equipment  

NASA Technical Reports Server (NTRS)

Heat-pipe action cools and maintains electronics at nearly constant temperature. System designed to control temperatures of spacecraft shelves or baseplates by combining honeycomb sandwich panel with reservoir of noncondensable gas and processing resulting device as variable-conductance heat pipe. Device provides flat surface for mounting heat-dissipating electronics that is effectively cooled and maintained at nearly constant temperature. Potentially useful in freeze drying, refrigeration, and air conditioning.

Tanzer, Herbert J.

1989-01-01

16

Electromagnetic Interference Tests for Electronic Equipment.  

National Technical Information Service (NTIS)

The report prescribes procedures and techniques for measuring frequencies and amplitudes of the electromagnetic interference characteristics (emission, compatibility, and susceptibility) of electronic and electromechanical equipment, systems and subsystem...

1974-01-01

17

Detailed Studies of Electron Cooling Friction Force.  

National Technical Information Service (NTIS)

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 des...

A. V. Fedotov

2005-01-01

18

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

19

Status of the Fermilab electron cooling project  

Microsoft Academic Search

A prototype of a 4.3-MeV electron cooling system has been assembled at Fermilab as part of the on-going R&D program in high-energy electron cooling. This electron cooler prototype will not demonstrate the actual cooling but it would allow to determine if the electron beam properties are suitable for antiproton beam cooling. An electron beam is accelerated by a 5-MV Pelletron

S. Nagaitsev; A. Burov; K. Carlson; V. Dudnikov; B. Kramper; T. Kroc; J. Leibfritz; M. McGee; G. Saewert; C. W. Schmidt; A. Shemyakin; A. Warner; S. Seletsky; V. Tupikov

2004-01-01

20

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

21

VORPAL Simulations Relevant to Coherent Electron Cooling  

Microsoft Academic Search

Coherent electron cooling (CEC)* combines the best features of electron cooling and stochastic cooling, via free-electron laser technology**, to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the â modulatorâ

G. I. Bell; D. L. Bruhwiler; A. V. Sobol; Ilan Ben-Zvi; Vladimir Litvinenko; Yaroslav Derbenev

2008-01-01

22

VORPAL simulations relevant to coherent electron cooling  

Microsoft Academic Search

Coherent electron cooling (CEC) [1] combines the best features of electron cooling and stochastic cooling, via free-electron laser technology [2], to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the

G. Bell; D. Bruhwiler; A. Sobol; I. Ben-Zvi; V. Litvinenko; Y. Derbenev

2008-01-01

23

Electromagnetic Pumps for Main Cooling Systems of Commercialized Sodium-Cooled Fast Reactor  

Microsoft Academic Search

An electromagnetic pump (EMP) has superior potential to improve the economic performance and ease of maintenance of sodium-cooled fast reactors. This study investigates the adequateness of a modular-type EMP system for large-sized (1,500MWe class) sodium-cooled fast reactors. A flow rate of over 500 m\\/min is required for the main circulating pump of such reactors. There is concern that such a

Kosuke AIZAWA; Yoshitaka CHIKAZAWA; Shoji KOTAKE; Kuniaki ARA; Rie AIZAWA; Hiroyuki OTA

2011-01-01

24

VORPAL Simulations Relevant to Coherent Electron Cooling  

SciTech Connect

Coherent electron cooling (CEC)* combines the best features of electron cooling and stochastic cooling, via free-electron laser technology**, to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the â modulatorâ and â kickerâ regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations*** of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results. In particular, we compare the semi-analytic binary collision model with electrostatic particle-in-cell (PIC).

Bell, G.I.; Bruhwiler, D.L.; Sobol, A.V.; Ben-Zvi, Ilan; Litvinenko, Vladimir; Derbenev, Yaroslav

2008-07-01

25

VORPAL simulations relevant to coherent electron cooling  

SciTech Connect

Coherent electron cooling (CEC) [1] combines the best features of electron cooling and stochastic cooling, via free-electron laser technology [2], to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the modulator and kicker regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations [3] of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results.

Bell,G.; Bruhwiler, D.; Sobol, A.; Ben-Zvi, I.; Litvinenko, V.; Derbenev, Y.

2008-06-23

26

SIMULATIONS OF HIGH-ENERGY ELECTRON COOLING.  

SciTech Connect

High-energy electron cooling of RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires a detailed calculation of the cooling process, which takes place simultaneously with various diffusive mechanisms in RHIC. In addition, many unexplored effects of high-energy cooling in a collider complicate the task of getting very accurate estimates of cooling times. To address these high-energy cooling issues, a detailed study of cooling dynamics based on computer codes is underway at Brookhaven National Laboratory. In this paper, we present an update on code development and its application to the high-energy cooling dynamics studies for RHIC.

FEDOTOV,A.V.; BEN-ZVI,I.; EIDELMAN, YU.; LITVINENKO, V.; MALITSKY, N.

2005-05-16

27

Fermilab electron cooling project: Engineering aspects of cooling section  

SciTech Connect

The Fermilab Electron Cooling project involves interacting a 4.3 MeV, 0.5 A DC electron beam with 8.9 GeV/c antiprotons in the FNAL Recycler Ring. This interaction occurs through a 20-meter long cooling section consisting of 10 solenoid modules. This cooling process would lead to an increase in the Tevatron collider luminosity needed to support RunIIb parameters. There are several important engineering aspects of this cooling section including: solenoid design, vacuum system design, magnetic shielding, support system, and alignment methods. Details of the engineering issues related to each of these areas is discussed.

Jerry R. Leibfritz et al.

2001-07-25

28

A System for Vapor Cooling Electronic Equipment.  

National Technical Information Service (NTIS)

The patent application pertains generally to heat transfer systems and more particularly to a closed system for cooling electronic equipment. A vapor cooling system comprises a liquid boiled by heat from a magnetron and collected and forced upward by the ...

H. Boehm

1976-01-01

29

Towards demonstration of electron cooling with bunched electron beam  

SciTech Connect

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

Fedotov, A.

2012-01-11

30

Planar Electromagnet Microwiggler for Free Electron Lasers.  

National Technical Information Service (NTIS)

An electromagnet planar microwiggler for use in free electron lasers was tested, constructed of current conductors wound on ferromagnetic cores. A prototype with a period of 1 cm and gap of 0.5 cm produced a peak field on axis in excess of 4.6 kG, with a ...

R. Stoner S. C. Chen G. Bekefi

1990-01-01

31

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

32

Advanced optical concepts for electron cooling  

Microsoft Academic Search

The results of explorations of non-traditional solutions of beam transport which could raise the electron cooling rates and efficiency are presented. The proposed optical elements, methods, and conceptual designs are summarized in the following. (1) Magnetized electron beam acceleration and transport with discontinuous solenoid to provide matching between the electron gun and solenoid of the cooling section. These concepts allow

Y. S. Derbenev

2000-01-01

33

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

34

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

35

Electronic cooling design and test validation  

Microsoft Academic Search

An analytical computer model has been used to design a counterflow air-cooled heat exchanger according to the cooling, structural and geometric requirements of a U.S. Navy shipboard electronics cabinet, emphasizing high reliability performance through the maintenance of electronic component junction temperatures lower than 110 C. Environmental testing of the design obtained has verified that the analytical predictions were conservative. Model

W. B. Murtha

1983-01-01

36

Electron Beam Size Measurements in the Fermilab Electron Cooling System.  

National Technical Information Service (NTIS)

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 si...

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

2006-01-01

37

Attainment of Electron Beam Suitable for Medium Energy Electron Cooling.  

National Technical Information Service (NTIS)

Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The ...

S. Seletskiy

2005-01-01

38

Electromagnetic electron beam instabilities - Hot, isotropic beams  

NASA Technical Reports Server (NTRS)

This paper considers the linear theory of electromagnetic instabilities driven by an electron beam in a homogeneous, nonrelativistic, Vlasov plasma. The beam is relatively hot, isotropic in its own frame, and streams parallel or antiparallel to a magnetic field B. Numerical solutions of the full dispersion equation for propagation parallel or antiparallel to B are presented, and the linear properties of the whistler heat flux and electron beam firehose instabilities are exhibited and compared. Under a broad range of parmameters the former mode has the lower beam speed threshold, and the larger maximum growth rate. In addition, it is demonstrated that, for a sufficiently large relative beam density, relative beam temperature, and plasma beta the whistler heat flux instability has a much lower beam speed threshold than the electrostatic electron beam instability. The application of these instabilities to first-order Fermi acceleration of electrons at space plasma shocks is discussed.

Gary, S. P.

1985-01-01

39

Capillary Assisted Thermosyphon For Shipboard Electronics Cooling.  

National Technical Information Service (NTIS)

Recent advances in capillary pumped loop technology were incorporated into the design of a vertical flat plate evaporator for cooling high power electronics aboard naval vessels. This investigation included the design, fabrication, and experimentation of ...

E. H. Larsen

2003-01-01

40

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 VORPAL 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. [Brookhaven National Lab, Upton, NY 11973 (United States); Bruhwiler, D. L.; Abell, D. T. [Tech-X Corp., Boulder, CO 80303 (United States); Sidorin, A. O. [JINR, Dubna (Russian Federation)

2006-03-20

41

Detailed Studies of Electron Cooling Friction Force  

NASA Astrophysics Data System (ADS)

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 VORPAL 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.

2006-03-01

42

ELECTRON COOLING IN THE RECYCLER COOLER  

SciTech Connect

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

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

2007-09-10

43

Investigation of Elliptical Cooling Channels for a Naval Electromagnetic Railgun.  

National Technical Information Service (NTIS)

The future Naval Electromagnetic Railgun will use a mega-ampere electrical current to generate an electromagnetic force which accelerates a projectile to hypersonic velocities. The applied current can raise the bulk temperature of the rails by over 100 de...

E. R. Kealey

2005-01-01

44

Electron Cooling Rates Characterization at Fermilab's Recycler.  

National Technical Information Service (NTIS)

A 0.1 A, 4.3 MeV DC electron beam is routinely used to cool 8 GeV antiprotons in Fermilab's Recycler storage ring. The primary function of the electron cooler is to increase the longitudinal phase-space density of the antiprotons for storing and preparing...

A. Shemyakin L. R. Prost

2007-01-01

45

Single Pass Electron Cooling Simulations for MEIC  

SciTech Connect

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

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

2013-12-01

46

Electromagnetic Turbulence Simulations with Kinetic Electrons  

NASA Astrophysics Data System (ADS)

Recently a new electromagnetic kinetic electron delta-f particle simulation model has been demonstrated to work well at large values of plasma beta times the ion-to-electron mass ratio [1,2]. The new simulation presented here uses a generalized split-weight scheme [3,4], where the adiabatic part is adjustable, along with a parallel canonical momentum formulation [5] and has been developed in three-dimensional toroidal flux-tube geometry. The model also includes electron-ion collisional effects and has been linearly benchmarked with continuum codes [6,7]. Electromagnetic simulations with kinetic electrons require a timestep approximately one-half that of electrostatic adiabatic electron simulations. Large box size simulations of 256 by 256 in units of ion gyroradius using a realistic mass ratios run well and detailed convergence studies have been done. Finite-beta reduction of energy transport, below the adiabatic electron level is observed for betas below the kinetic ballooning limit. For beta above the kinetic ballooning threshold fluxes are extremely high, and it is unlikely to be an experimentally relevant regime. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary. We have shown that the linear behavior of the zonal flow is not significantly affected by kinetic electrons. Zonal fields [9] are found to be very weak consistent with theoretical predictions for betas below the kinetic ballooning limit. Detailed spectral and cross-correlation analysis of the turbulent spectra will be presented in the various limits. Acknowledgments: Thanks to A.M. Dimits, D. Shumaker, LLNL; V.K. Decyk, J.N. Leboeuf UCLA, work done using the Summit Framework and supported by the DOE SciDAC Plasma Microturbulence Project. [1] Y. Chen and S.E. Parker, to appear in J. Comput. Phys. (2003). [2] Y. Chen, S.E. Parker, B.I. Cohen, A.M. Dimits, W.M. Nevins, D. Shumaker, V.K. Decyk and J.N. Leboeuf, to appear in Nuc. Fusion (2003). [3] I. Manuilskiy and W.W. Lee, Phys. Plasmas 7 1381 (2000). [4] Y. Chen and S.E. Parker, Phys. Plasmas 8 2095 (2001) [5] T.S. Hahm, W.W. Lee and A. Brizard, Phys. Fluids 31 1940 (1988). [6] W. Dorland et. al, Proc. 18th Int. Conf. on Fusion Energy, IAEA, Sorrento, Italy, 2000; W. Dorland, F. Jenko, M. Kotschenreuther and B.N. Rogers, Phys. Rev. Lett. 85, 5336 (2000). [7] J. Candy and R. Waltz, to appear in J. Comput. Physics (2003). [8] A.V. Gruzinov and P.H. Diamond, Phys. Plasmas 3 1854 (1996), L. Chen, Z. Lin R.B. White and F. Zonca, Nuc. Fusion 41 747 (2001); P.N. Gudzar, R.G. Kleva, A. Das and P.K. Kaw, Phys. Plasmas 8 3907 (2001).

Parker, Scott E.

2003-10-01

47

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

48

Electronic cooling design and test validation  

NASA Astrophysics Data System (ADS)

An analytical computer model has been used to design a counterflow air-cooled heat exchanger according to the cooling, structural and geometric requirements of a U.S. Navy shipboard electronics cabinet, emphasizing high reliability performance through the maintenance of electronic component junction temperatures lower than 110 C. Environmental testing of the design obtained has verified that the analytical predictions were conservative. Model correlation to the test data furnishes an upgraded capability for the evaluation of tactical effects, and has established a two-orders of magnitude growth potential for increased electronics capabilities through enhanced heat dissipation. Electronics cabinets of this type are destined for use with Vertical Launching System-type combatant vessel magazines.

Murtha, W. B.

1983-07-01

49

Influence of electron beam parameters on coherent electron cooling  

SciTech Connect

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

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

2012-05-20

50

Cooling of electrons in meteor trails  

NASA Astrophysics Data System (ADS)

An analysis is presented of inelastic collisions of electrons and air molecules in meteor trails, and the associated diffusion cooling. It is shown that the time of equalization of the electron temperature and the ambient air temperature is significantly less than that obtained in other studies which have taken into account only elastic collisions. In the former case, the equalization time amounts to several tens of milliseconds for the 95-105 km height range.

Levitskii, S. M.; Abdrakhmanov, N.

1981-08-01

51

Noise and Cooling in Electronics Packages  

Microsoft Academic Search

The noise produced by cooling air passing through electronics packages arises from two sources. One source is the noise of the air-moving fan of either an axial or centrifugal type. This noise may have both tonal and random components and is strongly dependent on the way that the fan is placed in the unit and on where its operation is

Richard H. Lyon; Arthur E. Bergles

2006-01-01

52

Stimulated electromagnetic emission near electron cyclotron harmonics in the ionosphere  

Microsoft Academic Search

Observations of electromagnetic emission stimulated by a high-frequency radio wave injected into the ionosphere from a ground-based powerful transmitter operated near harmonics of the ionospheric electron cyclotron frequency are reported. Significant changes in the spectrum of the stimulated electromagnetic radiation were obtained as the injected frequency was varied in small steps around these harmonics. The experimental results are attributed to

T. B. Leyser; B. Thide; H. Derblom; A. Hedberg; B. Lundborg; P. Stubbe; H. Kopka; M. Rietveld

1989-01-01

53

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

54

Electromagnetic Interference Measurements in Electronic Voice Switching Equipment Areas.  

National Technical Information Service (NTIS)

The report describes a measurement program, performed to determine electromagnetic interference characteristics of spaces in the Denver ARTCC and at the Millville, NJ RCAG site, where components of the Electronic Voice Switching (EVS) system may be instal...

M. V. Stone

1975-01-01

55

Communications-Electronic Intrasystem Electromagnetic Interference Measurement Techniques and Instrumentation.  

National Technical Information Service (NTIS)

This report concludes the results obtained during the Communications-Electronics Intrasystem Electromagnetic Interference Measurement Techniques and Instrumentation Project. The major effort consisted of an IEMCAP feasibility study, development of a broad...

L. E. Polisky J. W. Savage

1980-01-01

56

Communications-Electronic Intrasystem Electromagnetic Interference Measurement Techniques and Instrumentation.  

National Technical Information Service (NTIS)

This report presents the results obtained during the third quarter of the Communications-Electronics Intrasystem Electromagnetic Interference Measurement Techniques and Instrumentation Project. The period covered was 21 Dec. 1979 to 20 March 1980. The maj...

L. E. Polisky J. Savage

1980-01-01

57

Miniature loop heat pipes for electronics cooling  

Microsoft Academic Search

The paper is devoted to the development of miniature loop heat pipes (mLHPs) with a nominal capacity of 25–30 W and a heat-transfer distance up to 250 mm intended for cooling electronics components and CPU of mobile PC. It gives the results of investigating several prototypes of mLHPs incorporated into remote heat exchanger (RHE) systems in different conditions. It has

V. G. Pastukhov; Yu. F. Maidanik; C. V. Vershinin; M. A. Korukov

2003-01-01

58

Electron cooling device without bending magnets  

NASA Astrophysics Data System (ADS)

The scheme of an axisymmetric electron cooling device without bending magnets is proposed. Solutions for the most important elements, i.e., a gun and a recuperator, are considered. The main characteristics of the recuperator of the Faraday cup type having a reflector and a gun with a ring emitter are explored. In the gun, the beam is formed, the diameter of which is 40 mm and the dimension of a disturbance region is several millimeters.

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

1993-11-01

59

Electromagnetic Pumps for Fast Reactors Primary Cooling Circuits.  

National Technical Information Service (NTIS)

The review of the electromagnetic pump development for the main loops of the powerful atomic energy stations with fast neutron reactors is presented. The calculation results of the cylindrical pump at the p essure of 9x10 exp 5 Pa nad Na consumption of 15...

A. M. Andreev E. A. Bezgachev B. G. Karasev I. R. Kirillov A. P. Ogorodnikov

1977-01-01

60

Electromagnetic effects in relativistic electron beam plasma interactions  

SciTech Connect

Electromagnetic effects excited by intense relativistic electron beams in plasmas are investigated using a two-dimensional particle code. The simulations with dense beams show large magnetic fields excited by the Weibel instability as well as sizeable electromagnetic radiation over a significant range of frequencies. The possible relevance of beam plasma instabilities to the laser acceleration of particles is briefly discussed. 6 refs., 4 figs.

Kruer, W.L.; Langdon, A.B.

1985-02-13

61

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

62

Electron-ion collision operator in strong electromagnetic fields  

NASA Astrophysics Data System (ADS)

The pair electron-ion collision operator is found for the kinetic equation describing the one-particle drift distribution in strong electromagnetic fields [1]. The pair collisions are studied under the conditions when the oscillation velocity of an electron driven by an external electromagnetic wave is much larger than the electron drift velocity. The operator is presented in the Boltzmann form and describes collisions with both small and large changes of the particle momentum. In contrast with the Landau collision operator, which describes diffusion in the momentum space, the collision operator that we propose describes a new and very important effect, namely, Coulomb attraction of a wave-driven oscillating electron to an ion due to multiple returns of the electron to the same ion. This effect leads to a large increase of the collision cross-section of electron-ion collisions in strong laser fields, to increased efficiency of the Joule heating in plasma, to the generation of fast electrons through e-i collisions, etc. [4pt] [1] A. A. Balakin and G. M. Fraiman, Electron-ion collision operator in strong electromagnetic fields, EPL 93, 35001 (2011).

Fraiman, Gennadiy; Balakin, Alexey

2012-10-01

63

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

64

Electromagnetic environmental impact of power electronics equipment  

Microsoft Academic Search

A dramatic increase in the number of line-powered electronic equipment (computers and other office equipment, electronic ballasts, variable-speed drives, and consumer electronics, e.g., color televisions) has taken place. These items of equipment draw distorted, and often fluctuating, line current; they also generate high-frequency conducted and radiated noise due to the sharp edges of the waveforms characteristic of the switching power

RICHARD REDL

2001-01-01

65

Electromagnetic field generation by ATP-induced reverse electron transfer  

Microsoft Academic Search

This paper describes a mechanism to explain low-level light emission in biology. A biological analog of the electrical circuitry, modeled on the parallel plate capacitor, traversed by a helical structure, required to generate electromagnetic radiation in the optical spectral range, is described. The charge carrier required for the emissions is determined to be an accelerating electron driven by an ATP-induced

Richard H. Steele

2003-01-01

66

Electron-ion collision operator in strong electromagnetic fields  

NASA Astrophysics Data System (ADS)

The pair electron-ion collisions operator in strong electromagnetic fields is considered. In strong EM fields, the collision operator is derived allowing for the complex stochastic particle dynamics at the scattering. The resulting expression can be conditionally separated into the diffusion part (having a Landau-like operator form) and the fast-particle source.

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

2011-02-01

67

Electromagnetic Interference Generated from Fast Switching Power Electronic Devices  

Microsoft Academic Search

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

K. M. Muttaqi; M. E. Haque

2008-01-01

68

Communications-electronic intrasystem electromagnetic interference measurement technique and instrumentation  

Microsoft Academic Search

This report presents the results obtained during the second quarter of the communications-electronics intrasystem electromagnetic interference measurement techniques and instrumentation project. The period covered was 21 Sep. 1979 to 21 Dec 1979. The major efforts in the second quarter consisted of completing the IEMCAP feasibility study and developing a broadband measurement system for conducting EMC measurements. Bibtex entry for this

L. E. Polisky; T. E. Baldwin Jr.; J. Savage

1980-01-01

69

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

70

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

Code of Federal Regulations, 2010 CFR

... 2009-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2009-10-01

71

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

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Operating characteristics of electromagnetic, electronic, or electrical apparatus. 236.8 Section...Systems General § 236.8 Operating characteristics of electromagnetic, electronic, or electrical apparatus. Signal...

2013-10-01

72

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

73

Field measurements in the Fermilab electron cooling solenoid prototype  

SciTech Connect

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

A. C. Crawford et al.

2003-10-02

74

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

75

Progress with FEL-based coherent electron cooling  

SciTech Connect

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

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

2008-08-24

76

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

SciTech Connect

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

Hershcovitch,A.

2008-04-01

77

The solar coronal electron heating by short wavelength electromagnetic modes  

NASA Astrophysics Data System (ADS)

The electron heating of the solar coronal plasma has remained as one of the most important problems in solar physics. An explanation of the electron heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the electrons. Our objective here is to present an estimate for the electron heat in grate in the presence of finite amplitude short wavelength in comparison with the ion gyroradius dispersive electromagnetic (SWDEM) waves that propagate obliquely to the magnetic field in the solar corona, Specifically, it is demonstrated that the SWDEM waves can significantly contribute to the solar coronal electron heating via Joule heating involving electron-SWEDEM wave interactions. .

Shukla, Padma; Bingham, Robert; Stenflo, Lennart; Eliasson, B.

2010-11-01

78

The solar coronal electron heating by short wavelength electromagnetic modes  

NASA Astrophysics Data System (ADS)

The electron heating of the solar coronal plasma has remained as one of the most important problems in solar physics. An explanation of the electron heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the electrons. Our objective here is to present an estimate for the electron heating rate in the presence of finite amplitude short wavelength (in comparison with the ion gyroradius) dispersive electromagnetic (SWDEM) waves that propagate obliquely to the magnetic field in the solar corona. Specifically, it is demonstrated that the SWDEM waves can significantly contribute to the solar coronal electron heating via Joule heating involving electron-SWDEM wave interactions.

Shukla, P. K.; Bingham, R.

2006-10-01

79

Quantum electromagnetics of an electron near mirrors  

NASA Astrophysics Data System (ADS)

At a distance z from a perfect plane reflector of light (a perfect mirror) the total spin magnetic moment ? of an electron suffers (anisotropic) corrections ?? of relative order {delta;?}/{?} = {?? s}/{? 0} ? {e 2}/{(mz) 2}, provided ?0z ? 1. Here ? = 1 = c; ? 0 ? {|e|B 0}/{m} = ? s = ? c equals the spin-precession and cyclotron frequencies in the applied magnetic field B0. The radiative corrections in the opposite regime ?0z ? 1 (identified by stars ?) cannot be expressed in terms of magnetic moments alone; but {?? ?s}/{? 0} ? ( {e 2? 0}/{m 2z }) cos(2? 0z) . There are similarly-calculable but much larger corrections ?? c and ?? ?c to ? c. All such shifts are determined to leading order; the results are new except for ?? ?c. No wavenumber cutoff is needed. Subdivision of ?? into “Dirac” and “anomalous” parts proves eminently unhelpful. The appendices describe the renormalization procedures appropriate to such proximity effects; the classical and quantum models; and comment on the minor but often misunderstood role of mirror imperfections, and on cutoffs. Part II determines the shifts for an electron between parallel mirrors a distance L apart, as functions of position and of overline?0 ? {? 0L }/{?}. When overline?0 ? 1 , one finds {??}/{?} = {?? s}/{? 0} ? {e 2}/{(mL) 2}, while {?? c}/{? 0} ? {e 2}/{(mL)}. When overline?0 ? 1 , one finds {?? ?s}/{? 0} ? ( {e 2? 0}/{m 2L }) log[⋯] and {?? ?c}/{? 0} ? ( {e 2}/{mL}) log[⋯] , where [⋯] is |2 cos( {? overline?0}/{2})| or |2 sin( {?? 0}/{2})| . When such logarithms diverge, they must for perfect mirrors be replaced by log( {e 2? 20}/{m 2}) in ?? ?s, and by log( {e 2? 0}/{m}) in ?? ?c. For mirrors with finite skin depth ? 0 at frequency ? 0, they become log( ?0?0). Feynman-diagrammatic approaches, hitherto inconclusive, are reviewed. Reports that {??}/{?} ? {e 2}/{mL} stem either from an incorrect (irreparably gauge-dependent) argument, or, as shown by Kreuzer, apply only to {??( Dirac) }/{?} and to {??( anomalous) }/{?} separately, but not to their observable sum {??}/{?} itself. Appendices cover the technicalities of renormalization and position-dependence with partially discretized field modes.

Barton, G.; Fawcett, N. S. J.

1988-11-01

80

Communications-electronic intrasystem electromagnetic interference measurement techniques and instrumentation  

Microsoft Academic Search

This report presents the results obtained during the third quarter of the Communications-Electronics Intrasystem Electromagnetic Interference Measurement Techniques and Instrumentation Project. The period covered was 21 Dec. 1979 to 20 March 1980. The major effort in the third quarter consisted of completing the broadband measurement technique description and initiating the evaluation of MIL-STD-461A techniques. Bibtex entry for this abstract Preferred

L. E. Polisky; J. Savage

1980-01-01

81

Electron cooling for low-energy RHIC program  

SciTech Connect

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

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

2009-08-31

82

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

NASA Astrophysics Data System (ADS)

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. Lécrivain, 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 87Rb atoms to quantum degeneracy. Pure Bose-Einstein condensates containing 106 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.; Lécrivain, M.

2005-10-01

83

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

84

Kinetic electrons in global electromagnetic gyrokinetic particle simulations  

NASA Astrophysics Data System (ADS)

Employing an electromagnetic gyrokinetic simulation model,ootnotetextZ. Lin and L. Chen, Phys. Plasmas 8, 1447 (2001). kinetic electron dynamics in global tokamak geometry is investigated. The massless fluid electron model is developed as a base. We further evolve gyrokinetic equations for non-adiabatic kinetic electrons. To obtain the magnetic perturbation, the fluid-kinetic hybrid electron model^1 employs the inverse of the Faraday's law. Instead, the Ampere's law is used as a closure relation to avoid uncertainties in estimating ue|, the moment of the electron velocities. The physics goal is to investigate the finite beta effects on the turbulent transport, as well as ? particle driven turbulence.ootnotetextI. Holod, Z. Lin, et al., this conference. This work is supported by Department of Energy (DOE) Cooperative Agreement No. DE-FC02-03ER54695 (UCI), DOE Contract No. DE-AC02-76CH03073 (PPPL).

Nishimura, Y.; Wang, W.

2005-10-01

85

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

86

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

87

Cooling structure for EMC shielded high frequency electronics  

Microsoft Academic Search

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

W. Peter Siebert

2006-01-01

88

Facilities for Improving Evaluations of Electromagnetic Susceptibilities of Weapon Systems and Electronic Equipment.  

National Technical Information Service (NTIS)

A preliminary design of an improved testing facility for evaluating the electromagnetic susceptibility of weapon systems and electronic equipment is presented. The facility features a combination of the transverse electromagnetic (TEM) cell for low-freque...

M. T. Ma M. L. Crawford

1989-01-01

89

Application of superconductor–semiconductor Schottky barrier for electron cooling  

Microsoft Academic Search

Electronic cooling in superconductor–semiconductor–superconductor structures at sub kelvin temperatures has been demonstrated. Effect of the carrier concentration in the semiconductor on performance of the micro-cooler has been investigated.

Alexander Savin; Mika Prunnila; Jouni Ahopelto; Pasi Kivinen; Päivi Törmä; Jukka Pekola

2003-01-01

90

Nonlinear electromagnetic gyrokinetic particle simulations with the electron hybrid model  

NASA Astrophysics Data System (ADS)

The electromagnetic model with fluid electrons is successfully implemented into the global gyrokinetic code GTC. In the ideal MHD limit, shear Alfven wave oscillation and continuum damping is demonstrated. Nonlinear electromagnetic simulation is further pursued in the presence of finite ?i. Turbulence transport in the AITG unstable ? regime is studied. This work is supported by Department of Energy (DOE) Grant DE-FG02-03ER54724, Cooperative Agreement No. DE-FC02-04ER54796 (UCI), DOE Contract No. DE-AC02-76CH03073 (PPPL), and in part by SciDAC Center for Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas. Z. Lin, et al., Science 281, 1835 (1998). F. Zonca and L. Chen, Plasma Phys. Controlled Fusion 30, 2240 (1998); G. Zhao and L. Chen, Phys. Plasmas 9, 861 (2002).

Nishimura, Y.; Lin, Z.; Chen, L.; Hahm, T.; Wang, W.; Lee, W.

2006-10-01

91

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

92

Radiative recombination of ions and nuclei in electron cooling systems  

NASA Astrophysics Data System (ADS)

Experimental data on rates for the radiative recombination of nuclei (from helium to uranium) and various ions in interaction with an electron beam in electron cooling systems are reviewed. An analysis of the experimental data has yielded the dependence of the radiative recombination rate on the relative electron energy appreciably differently than the theoretical models obtained earlier by H. Kramers and R. Schuch. In addition, it is shown that the radiative recombination rate of nuclei in the experiment depends on the transverse electron energy as T {?/-0.82},which is also different from the results of the calculations by the theoretical model proposed by M. Bell and J. Bell. Experimental data on the cooling of ions in intermediate charge states are analyzed and the dependence of the radiative recombination rate on the charge state of the ion (electron-shell configuration) is shown. For some ion charge states, the rate of the process is of a resonance character. Loss to radiative recombination in the electron cooling system of the NICA Booster is evaluated for the Au32+, Au33+, Au50+, and Au51+ ion beams. Limitations imposed on the Au79+ beam lifetime by radiative recombination in the electron cooling system of the NICA Collider are analyzed. Possible ways to decrease the radiative recombination rate of nuclei by selecting the parameters of the electron cooling system for the NICA Collider are proposed.

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

2012-07-01

93

Superconducting shield for solenoid of electron cooling system  

NASA Astrophysics Data System (ADS)

Ensuring the high homogeneity of a magnetic field in the straight solenoid of an electron cooling system is a very important task. In the electron cooling system of the collider in the NICA project, it is planned to use superconducting solenoids for the generation of a longitudinal magnetic field. Using of the superconducting shield is proposed to achieve the required homogeneity of the magnetic field in the cooling section. This article discusses the design of the superconducting shield and presents experimental and numerical studies into the homogeneity of the magnetic field in solenoids with the superconducting shield.

Agapov, N. N.; Donets, D. E.; Drobin, V. M.; Kulikov, E. A.; Malinovski, H.; Pivin, R. V.; Smirnov, A. V.; Prokofichev, Yu. V.; Trubnikov, G. V.; Dorofeev, G. L.

2012-07-01

94

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

95

Stability of arbitrary electron velocity distribution functions to electromagnetic modes  

SciTech Connect

The stability of general electron distribution functions to purely electromagnetic modes is considered, so as to generalize the well-known stability analysis for bi-Gaussian distribution functions. The expansion of an arbitrary nonrelativistic distribution function into a modified version of Hermite-Gaussian modes yields the dispersion relation for electromagnetic modes in a compact form that depends on the coefficients of the expansion as well as the well-known plasma dispersion function and its derivatives. The coefficients of the expansion that enter the dispersion relation depend only on the zeroth and second moments from the direction of high temperature. The general dispersion relation is solved analytically for the frequency in the low anisotropy (kinetic) limit. Purely imaginary solutions can be found for distribution functions symmetric in the direction of the wavenumber. If, in addition to being symmetric, the distribution function is separable, the only quantity from the high-temperature direction that enters the equation for the frequency of the electromagnetic wave is the variance.

Tzoufras, M.; Ren, C.; Tsung, F. S.; Tonge, J. W.; Mori, W. B.; Fiore, M.; Fonseca, R. A.; Silva, L. O. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Departments of Mechanical Engineering and Physics and Astronomy, and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Department of Electrical Engineering and Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); GoLP/Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal)

2007-06-15

96

Effects of e-beam parameters on coherent electron cooling  

SciTech Connect

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

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

2011-03-28

97

Simulation on Generation of Electromagnetic Waves from Electron Beam: Application to Solar Type III Radio Bursts  

NASA Astrophysics Data System (ADS)

Using a two-dimensional electromagnetic and relativistic particle-in-cell (2-D EM PIC) code, we show that electromagnetic waves are excited with near fundamental plasma frequency from relativistic electron beam instability. It is also shown that electromagnetic waves with almost second harmonics can be emitted after a little time delay.

Sugiyama, D.; Sakai, J.; Nambu, M.

98

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

Microsoft Academic Search

This paper presents a two-phase cooling method using the R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PEs), such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles. 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; Curtis William Ayers; Burak Ozpineci; Kirk T. Lowe

2007-01-01

99

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

100

Electronics for a highly segmented electromagnetic calorimeter prototype  

NASA Astrophysics Data System (ADS)

A prototype of a highly segmented electromagnetic calorimeter has been developed. The detector tower is made of 24 layers of PHASE2/MIMOSA23 silicon sensors sandwiched between tungsten plates, with 4 sensors per layer, a total of 96 MIMOSA sensors, resulting in 39 MPixels for the complete prototype detector tower. The paper focuses on the electronics of this calorimeter prototype. Two detector readout and control systems are used, each containing two Spartan 6 and one Virtex 6 FPGA, running embedded Linux, each system serving 12 detector layers. In 550 ms a total of 4 Gbytes of data is read from the detector, stored in memory on the electronics and then shipped to the DAQ system via Gigabit ethernet.

Fehlker, D.; Alme, J.; van den Brink, A.; de Haas, A. P.; Nooren, G.-J.; Reicher, M.; Röhrich, D.; Rossewij, M.; Ullaland, K.; Yang, S.

2013-03-01

101

First results of electron cooling experiments at LEAR  

Microsoft Academic Search

The first results are presented of electron cooling experiments in the Low-Energy Antiproton Ring (LEAR) at CERN, performed with a proton beam of about 50 and 21 MeV. The number of stored protons ranged from 107 to 3 × 109. Cooling times of the order 1 s and proton drag rates of up to 0.7 MeV\\/s were obtained. The capture

Helmut Poth; W. Schwab; B. Seligmann; M. Wörtge; A. Wolf; S A Baird; M. Chanel; H. Haseroth; C. E. Hill; R. Ley; Django Manglunki; G. Tranquille; J. L. Vallet; P. F. Dittner

1989-01-01

102

Electromagnetic instabilities driven by cool heavy ion beams. [interacting with solar wind  

NASA Technical Reports Server (NTRS)

The effects of the mass and density of cool, heavy ion beams on the linear and nonlinear characteristics of right-hand resonant and nonresonant electromagnetic ion beam instabilities are analyzed. The magnetic helicity and Alfven speed for a computer simulated complete linear dispersion equation for electromagnetic instabilities are examined. The data reveal that the maximum growth rate of the resonant mode and the threshold velocity of the nonresonant mode decrease with beam mass; however, the maximum growth rate of the nonresonant mode and the threshold velocity of the resonant mode are independent of the beam mass. The role reversal of the instabilities which occur when a heavy ion beam is the more dense component is studied. The nonlinear behavior of the instabilities is described; variations in the magnetic field fluctuation levels and the beam mass dependence are investigated. It is observed that at low beam density the magnetic field fluctuation level increases with beam mass and at higher beam density the fluctuation level correlates with the core mass. The instability data are applied to observations of Venus and the Comet Giacobini-Zinner.

Winske, D.; Gary, S. P.

1986-01-01

103

Search for electron EDM with laser cooled radioactive atom  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

104

Cooling technology for electronic equipment; Proceedings of the International Symposium, Honolulu, HI, Mar. 1987  

NASA Astrophysics Data System (ADS)

Design and applications aspects of electronic-hardware cooling systems are examined in reviews and reports. Topics addressed include natural-convection air-cooling techniques, forced-convection air-cooling techniques, liquid cooling techniques, conduction cooling and internal resistances, thermal analysis and computer modeling, and thermal systems in electronic equipment. Diagrams, drawings, graphs, photographs, and tables of numerical data are provided.

Aung, Win

105

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

PubMed

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices. PMID:10608306

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

2000-01-01

106

Cooling Section Solenoid for the 5 MeV Fermilab Electron Cooling Project  

Microsoft Academic Search

The proposed electron cooling section solenoid will consist of ten 2-m long modules with a common ferromagnetic shield. Each module is a solenoid with a maximum longitudinal field of 150 G, flanked by 8-cm gaps for diagnostics, pump-out ports and correction coils. This paper discusses requirements on each module as well as the design criteria that would allow to keep

S. Nagaitsev; A. C. Crawford; V. Kashikhin; A. Makarov

2000-01-01

107

Arbitrary plasma shape and trapped electron modes in the GEM gyrokinetic electromagnetic turbulence simulation code  

Microsoft Academic Search

Here the recent developments in GEM, a quite comprehensive Gyrokinetic Electromagnetic (GEM) turbulence code are described. GEM is a deltaf particle turbulence simulation code that has kinetic electrons and electromagnetic perturbations. The key elements of the GEM algorithm are: (1) the parallel canonical formulation of the gyrokinetic system of equations; (2) an adjustable split-weight scheme for kinetic electrons; and (3)

Yang Chen; Scott Parker; Jianying Lang

2006-01-01

108

Cooling electronic equipment at simulated high altitude in hypobaric chambers  

NASA Astrophysics Data System (ADS)

An air cooling system has been designed to minimize electronic equipment failures during simulated exposures to 9,000 meters (29,000 ft) in hypobaric chambers. Air density, critical to convective heat transfer during electronic equipment operations, diminishes rapidly below 830 grams cubic meter (16,000 ft, 5,000 meters) resulting in equipment failures. Forced convection, using fans, can be effective up to 6,000meters but extensive equipment failures occur at higher altitudes. A newly designed cooling system incorporates a micrometer-like air flow control nozzle that directs compressed air onto the subject area. The design also accelerates surrounding air molecules to create a highly amplified flow by adding the entrained ambient air to the compressed air. Air flows may be directed on heat exchangers, power supplies, through ventilation ports, ports, to assist fan units, and for general in-cabinet cooling.

Devine, James A.

1987-08-01

109

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

110

Electron diffusion in tokamaks due to electromagnetic fluctuations  

SciTech Connect

Calculations for the stochastic diffusion of electrons in tokamaks due to a spectrum of electromagnetic drift fluctuations are presented. The parametric dependence of the diffusion coefficient on the amplitude and phase velocity of the spectrum, and the bounce frequency for the electrons is studied. The wavenumber spectrum is taken to be a low order (5 x 5) randomly-phased, isotropic, Monotonic spectrum extending from k /sub perpendicular min/ approx. = ..omega../sub ci//c/sub s/ to k/sub perpendicular max/ approx. = 3..omega../sub pe//c with different power laws of decrease phi k approx. = phi 1/k/sup m/, 1 less than or equal to m less than or equal to 3. A nonlinear Ohm's law is derived for the self-consistent relation between the electrostatic and parallel vector potentials. The parallel structure of the fluctuations is taken to be such that k parallel/sup nl/upsilon/sub e/ < w/sub k/ due to the nonlinear perpendicular motion of the electrons described in the nonlinear Ohm's law. The diffusion coefficient scales approximately as the neo-Alcator and Merezhkin-Mukhovatoc empirical formulas for plasma densities above a critical density.

Horton, W.; Choi, D.I.; Yushmanov, P.N.; Parail, V.V.

1986-05-01

111

Effect of a Strong Radiation Field on an Electron Moving in a Plane Electromagnetic Wave.  

National Technical Information Service (NTIS)

The effect of an external radiation field with arbitrary spectral composition on an electron which is moving in the field of a monochromatic plane electromagnetic wave (first wave) is considered. The change in the average energy of a relativistic electron...

I. M. Ternov V. R. Khalilov A. F. Zhuravlev G. A. Chizhov

1973-01-01

112

Designs for a 10.6 micrometer Electromagnetic Wiggler Free-Electron Laser (FEL).  

National Technical Information Service (NTIS)

The possibility of developing gyrotron-powered electromagnetic wiggler free-electron laser (FEL) oscillators is of considerable interest for reducing the electron energy required for operation in the infrared spectrum. This memorandum considers the design...

A. W. Fliflet W. M. Manheimer

1993-01-01

113

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

114

Electromagnetism.  

National Technical Information Service (NTIS)

This program demonstrates the characteristics of electromagnetism with iron filings and a compass. It shows the left-hand rule for determining current flow in an electromagnet. It illustrates the use of a dot and a cross to designate current flow.

1994-01-01

115

Electron trajectories and gain for an electromagnetic wiggler with ion-channel guiding  

SciTech Connect

A theory is developed for a free-electron laser with electromagnetic wiggler and ion-channel guiding. The electron trajectories due to a large amplitude backward propagating electromagnetic wiggler and an ion-channel electrostatic field are obtained and the stability of orbits is discussed. Then the gain equation describing the interaction between an electron and the radiation field is derived in the low-gain-per-pass limit. The results of a numerical study of electron orbits and gain are presented and discussed. It is shown that the maximum gain obtained in an electromagnetic wiggler is about twice the maximum gain obtained in a magnetostatic wiggler.

Esmaeilzadeh, Mahdi; Ghafouri, Vahid; Taghavi, Amin; Namvar, Esmaeil [Department of Physics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of); Department of Physics, Tarbiat Moallem University, 49 Dr Mofatteh Avenu, Tehran 15614 (Iran, Islamic Republic of)

2006-04-15

116

Electron Cooling and Debye-Waller Effect in Photoexcited Bismuth  

NASA Astrophysics Data System (ADS)

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

Arnaud, B.; Giret, Y.

2013-01-01

117

Progress on a cryogenically cooled RF gun polarized electron source  

SciTech Connect

RF guns have proven useful in multiple accelerator applications. An RF gun capable of producing polarized electrons is an attractive electron source for the ILC or an electron-ion collider. Producing such a gun has proven elusive. The NEA GaAs photocathode needed for polarized electron production is damaged by the vacuum environment in an RF gun. Electron and ion back bombardment can also damage the cathode. These problems must be mitigated before producing an RF gun polarized electron source. In this paper we report continuing efforts to improve the vacuum environment in a normal conducting RF gun by cooling it with liquid nitrogen after a high temperature vacuum bake out. We also report on a design of a cathode preparation chamber to produce bulk GaAs photocathodes for testing in such a gun. Future directions are also discussed.

Fliller, R.P., III; Edwards, H.; /Fermilab

2006-08-01

118

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.

119

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

120

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

121

Secondary electron current loss in electron cooling devices  

NASA Astrophysics Data System (ADS)

The efficiency of secondary electron capture in a recuperator with a longitudinal magnetic field is evaluated. To characterize this efficiency, the value of the collector secondary emission coefficient is introduced, for the calculation of which a simple formula is proposed. The effects determining the difference between the current losses in straight systems and devices with bending magnets are analyzed. It is experimentally shown that there is no unambiguous relation between the efficiency of the secondary electron capture by the collector and the current loss. The mechanism which determines the current loss in straight systems is suggested.

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

1994-12-01

122

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

Microsoft Academic Search

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

Akihiro Oto; Nobuyuki Naohara; Masayoshi Ishida; Toshitaka Kuroki; Kenji Katsuki; Ryouji Kumazawa

1995-01-01

123

Feasibility of Electron Cooling for Low-Energy RHIC Operation  

SciTech Connect

A concrete interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has recently emerged. Providing collisions in this energy range, which in the RHIC case is termed 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of a critical point on the QCD phase diagram. However, luminosity projections are relatively low for the lowest energy points of interest. Luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes the expected luminosity improvement with electron cooling, possible technical approaches and various limitations.

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

2008-04-01

124

Spectral structure of stimulated electromagnetic emissions between electron cyclotron harmonics  

Microsoft Academic Search

Experimental results concerning the spectrum of stimulated electromagnetic emissions (SEE) in the sidebands of a powerful high-frequency electromagnetic ordinary mode pump wave are presented. The pump wave was vertically injected into the ionospheric F region from the Sura ionospheric modification facility in Russia. We report detailed measurements of the commonly observed continuum, downshifted maximum, and broad upshifted maximum emissions for

T. B. Leyser; B. Thidé; M. Waldenvik; S. Goodman; V. L. Frolov; S. M. Grach; A. N. Karashtin; G. P. Komrakov; D. S. Kotik

1993-01-01

125

Two-phase flow instability analysis for transient electronics cooling  

Microsoft Academic Search

Because of increasing power densities, refrigeration systems are being explored for two-phase cooling of ultra high power electronic components. This paper presents a framework for the transient analysis of pressure-drop refrigerant flow instabilities under both steady-state and transient imposed heat loads. Based on an analytical two-phase flow model, the system pressure and other effects on flow characteristics are quantitatively studied,

TieJun Zhang; Yoav Peles; John T. Wen; Michael K. Jensen

2010-01-01

126

Two-Phase Closed-Loop Thermosyphon for Electronic Cooling  

Microsoft Academic Search

This study experimentally investigated the thermal performance of a two-phase closed-loop thermosyphon with a thermal resistance model for electronic cooling. The evaporator, rising tube, condenser, and falling tube, which are the four main devices, formed a closed-loop system with water as the working fluid. The experimental parameters were the evaporator surface type, fill ratio of working fluid, and input heating

C.-C. Chang; S.-C. Kuo; M.-T. Ke; S.-L. Chen

2010-01-01

127

Evaporative spray cooling of power electronics using high temperature coolant  

Microsoft Academic Search

A pressure atomized evaporative spray cooling nozzle array was used to thermally manage the power electronics of a 3 phase inverter module. The module tested was a COTS module manufactured by Semikron, Inc., and has a maximum DC power input of 180 kW (450 VDC and 400 A) with 25degC coolant. However, the standard heat sink that the module uses

Louis J. Turek; Daniel P. Rini; Benjamin A. Saarloos; Louis C. Chow

2008-01-01

128

Interaction of coherent electromagnetic waves with relativistic electrons in a medium  

Microsoft Academic Search

A MECHANISM is proposed here for producing coherent photons by the interaction in a medium of relativistic electrons (moving with velocity greater than the electromagnetic phase velocity in the medium) with coherent electromagnetic waves incident in the opposite direction. A new effect of potential use is exhibited; it is a consequence of two distinct physical phenomena acting synergistically to result

S. Schneider; R. Spitzer

1974-01-01

129

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

130

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

131

Efficiency of vacuum cleaning by an electron beam in the prototype of electron-cooling device  

NASA Astrophysics Data System (ADS)

A vacuum chamber of the electron-cooling device prototype was effectively cleaned by an electron beam. The outgassing rate of the vacuum chamber was decreased to values of order 10 -15 mbar l/s cm 2, and the coefficient of electron-induced desorption was lower than 10 -5 molecule/electron. In the absence of vacuum pumps a vacuum better than 10 -10 mbar was reached at a stationary current up to 2 A.

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

1998-02-01

132

Prospectus for an electron cooling system for the recycler  

SciTech Connect

The Recycler ring was added to the Main Injector (MI) project in 1997 as means to recover the antiprotons remaining at the end of Tevatron stores and to serve as a second stage accumulator to raise the maximum stack current. This report describes an electron cooling system with substan-tially higher stack capacity than the Recycler stochastic cooling system which could be brought into operation toward the end of Run II. It is the major component of a program to double the de-sign Run II luminosity and should have a positive effect on integrated luminosity soon after turn-on. The upgrade potential is intended to meet the longer term needs of the Laboratory?s luminosity upgrade program. The current experience with electron cooling is discussed to provide the ratio-nale for the choice of design parameters and to make clear the needs for additional development work. Both analytical and numerical development of the theory has been pursued to confirm that the limits in principle are well beyond foreseen need. The specific hardware described is not the only realization that has been considered, but it is in some ways the most conservative. The gen-eral scheme of using an electrostatic accelerator with high efficiency charge recovery was actively discussed in the 1980?s. Recent developments have served to build confidence in this approach, but, by whatever means realized, a Recycler electron cooling system will require significant extension of current practice. The Prospectus incorporates the ideas and understanding current 15 September 1998. Rapid progress toward a comprehensive development plan at this time means that its details will already differ from ideas now current.

J.A. MacLachlan, Editor

1998-11-01

133

Heating of the lower ionosphere electrons by electromagnetic radiation of lightning discharges  

SciTech Connect

This report investigates the heating effects on electrons that occur at the lower edge of the ionosphere due to the incidence of electromagnetic pulses radiated from discharges of lightning. Two tradiational models of the median return stroke is also considered.

Nickolaenko, A.P. [Institute of Radio Astronomy, Kharkov (Ukraine)] [Institute of Radio Astronomy, Kharkov (Ukraine); Hayakawa, M. [Univ. of Electro-Communications, Tokyo (Japan)] [Univ. of Electro-Communications, Tokyo (Japan)

1995-11-15

134

Graphical Study of Electromagnetic Wave Accessibility in Tokamak Plasmas Near the Electron-Cyclotron Frequency.  

National Technical Information Service (NTIS)

The accessibility of electron frequency range electromagnetic waves in magnetized inhomogeneous tokamak plasmas is studied using the cold plasma model. Simple equations for cutoff and resonance surfaces are obtained for parabolic density profile plasma. U...

C. S. Shibata A. Montes

1986-01-01

135

Electromagnetic-wave propagation and amplification in overdense plasmas: Application to free electron lasers  

NASA Astrophysics Data System (ADS)

Considering a propagation of electromagnetic (EM) waves through overdense homogeneous plasmas, a new regime of amplification of EM waves with frequencies below the plasma frequency has been found. An application to free electron lasers is suggested.

Matsko, Andrey B.; Rostovtsev, Yuri V.

1998-12-01

136

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

DOEpatents

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

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

2013-07-23

137

High power electronic devices cooling at minimum ventilation power  

NASA Astrophysics Data System (ADS)

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

Fabbri, Giampietro

2008-01-01

138

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

139

Electromagnets  

NSDL National Science Digital Library

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

Vu Bioengineering Ret Program

140

Rotational Cooling of HD+ by Superelastic Collisions with Electrons  

NASA Astrophysics Data System (ADS)

Rotational cooling of HD+ by superelastic collisions (SEC) with electrons was observed at the Heidelberg test storage ring by merging a beam of rotationally hot HD+ ions with an electron beam at zero relative energy. Neutral fragments resulting from DR events were recorded at different electron densities using a high resolution imaging detector and a large-area, energy sensitive detector. The data allowed to deduce the time dependence of the population of three groups of rotational angular momentum states J built on the vibrational ground state of the ion together with the corresponding DR rate coefficients. The latter are found to be (statistical uncertainties only) langle?rangle0,1,2 = 3.8(1), langle?rangle3,4 = 4.0(2), and langle?rangle5,6,7 = 9.0(1.3) in units of 10-8 cm3/s, in reasonable agreement with the average values derived within the MQDT approach. The time evolution of the population curves clearly reveals that rotational cooling by SEC takes place, which can be well described by using theoretical SEC rate coefficients obtained by combining the molecular R-matrix approach with the adiabatic nuclear rotation approximation. We verify the ?J = -2 coefficients, which are predicted to be dominant as opposed to the ?J = -1 coefficients and to amount to (1 - 2) · 10-6 cm3/s, to within 30%.

Schwalm, D.; Shafir, D.; Novotny, S.; Buhr, H.; Altevogt, S.; Faure, A.; Grieser, M.; Harvey, A. G.; Heber, O.; Hoffmann, J.; Kreckel, H.; Lammich, L.; Motapon, O.; Nevo, I.; Pedersen, H. B.; Rubinstein, H.; Schneider, I. F.; Tennyson, J.; Waffeu Tamo, F. O.; Wolf, A.; Zajfman, D.

2011-07-01

141

Competing Channels for Hot-Electron Cooling in Graphene  

NASA Astrophysics Data System (ADS)

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 (Telectron 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.

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

2014-06-01

142

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

143

Efficiency improvement of an electron collector intended for electron cooling systems using a Wien filter  

NASA Astrophysics Data System (ADS)

An efficient collector for high-voltage systems of electron cooling is presented. Its efficiency (ratio of the reflected electron current to the current of the main beam) is greatly improved by suppressing the reflected particle flux in the Wien filter. Secondary electrons deflect in crossed transverse electric and magnetic fields and are absorbed by a special receiver plate (secondary collector). The filter is designed so that the whole backward flow of electrons deflects even if the trajectory and main beam profile are distorted insignificantly. Experiments carried out on a special-purpose test bench show that such a filter raises the efficiency of the collector hundredfold (up to 10-6).

Bryzgunov, M. I.; Ivanov, A. V.; Panasyuk, V. M.; Parkhomchuk, V. V.; Reva, V. B.

2013-06-01

144

INTERACTION OF ELECTROMAGNETIC WAVE AND PLASMA SLAB WITH PARTIALLY LINEAR AND SINUSOIDAL ELECTRON DENSITY PROFILE  

Microsoft Academic Search

Interaction of an electromagnetic wave and an inhomoge- neous plasma slab with electron distribution in the form of partially linear and sinusoidal proflles is analysed to determine new re?ection, absorbtion and transmission characteristics. Broadband and tunable absorbtion performance of the plasma layer accompanied with narrow- band re?ection characteristic is presented as the function of electron density proflle parameters and external

S. Gurel; Emrah Oncu

2009-01-01

145

Long term exposure electromagnetic effects on discrete analog and digital electronic devices  

Microsoft Academic Search

A determination is made of the effects of long term exposure of analog and digital electronic devices to electromagnetic (EM) fields in the radio frequency range of 700 MHz to 18 GHz. Test results are used to determine short term and long term reliability of electronic devices and systems when exposed to EM environments. This study involves design and fabrication

G. J. Erickson; A. J. Pesta

1998-01-01

146

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

147

An experimental investigation of free convection cooling of electronic equipment  

NASA Astrophysics Data System (ADS)

An experimental study of free convection cooling of electronic components on PWB, which was placed horizontally in the cabinets, was carried out using the following two types of model cabinet: (1) the cabinets (200 x 150 mm in cross section, 80 mm high), which were made of acrylic resins plates (4 mm thick), had the ventilating small holes in the top panel and the bottom panel of them; and (2) the two-dimensional models of the cabinet (160 x 380 mm in cross section and 80 mm high) had many slits in the top panel of them. Numerical values of velocity of the ventilation, which were estimated by the heat balance analysis using the measured temperature, agreed with the values directly measured by LDV. It was demonstrated that the flow rate of ventilation could be estimated using the obtained relation between the ventilating air velocity and the mean temperature excess on the inner wall surface of the cabinets.

Miyamoto, M.; Katoh, Y.; Sakata, M.

1985-10-01

148

Electron cooling by diffusive normal metal-superconductor tunnel junctions  

NASA Astrophysics Data System (ADS)

We investigate heat and charge transport in NN'IS tunnel junctions in the diffusive limit. Here, N and S are massive normal and superconducting electrodes (reservoirs), N' is a normal metal strip, and I is an insulator. The flow of electric current in such structures at subgap bias is accompanied by heat transfer from the normal metal into the superconductor, which enables refrigeration of electrons in the normal metal. We show that the two-particle current due to Andreev reflection generates Joule heating, which is deposited in the N electrode and dominates over the single-particle cooling at low enough temperatures. This results in the existence of a limiting temperature for refrigeration. We consider different geometries of the contact, one dimensional and planar, which are commonly used in the experiments. We also discuss the applicability of our results to a double-barrier SINIS microcooler.

Vasenko, A. S.; Bezuglyi, E. V.; Courtois, H.; Hekking, F. W. J.

2010-03-01

149

Injection of ballistic hot electrons and cool holes in a two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

We have constructed a novel magnetic spectrometer to study the dynamics of hot electrons and cool missing electron states injected by quantum point contacts in the two-dimensional electron gas of a GaAs-Al xGa 1- x As heterostructure. The mean free path of these quasi-particles is found to be longer than recent theoretical estimates. The injection energy of the particles is found to be anomalously low as the point contact approaches pinch-off, and also for high bias voltages.

Williamson, J. G.; van Houten, H.; Beenakker, C. W. J.; Broekaart, M. E. I.; Spendeler, L. I. A.; van Wees, B. J.; Foxon, C. T.

1990-04-01

150

Optimal Fan Arrangement for Electronic Equipment with Multi-Fan CoolingSystem including Air Cooled Heat Sink with Fan  

NASA Astrophysics Data System (ADS)

Parametric study is conducted for optimizing the fan arrangement of the electronic equipment with several fans inthe equipment. Those fans are cooling for central processing unit (CPU), for power supply unit (PSU), and for the other devices in the equipment (system exhaust fan). We have used the Taguchi method of the experimental design for finding the optimal arrangement of those fans. The result shows system fans with high wind capacity does not always mean to enhance the cooling performance of the electronic equipment. When there is a system exhaust fan, it is recommended to set flow direction of CPU fan to up-flow, it is just opposite to flow direction of commercial CPU fan. This setting enables to exhaust the hot wasted air from CPU very efficiently. It is also found that the separation of the CPU from the PSU cooling system is an effective way to cool both components respectively.

Matsushima, Hitoshi; Terakado, Shuichi; Asano, Ichirou

151

A FIRST LOOK AT BEAM DIAGNOSTICS FOR THE RHIC ELECTRON COOLING PROJECT.  

SciTech Connect

High energy electron cooling [1] is essential to meet the luminosity specification for RHIC II [2]. In preparation for electron cooling, an Energy Recovery Linac (ERL) test facility [3] is under construction at BNL. A preliminary description of Diagnostics for the ERL was presented at an earlier workshop [4]. A significant portion of the eCooling Diagnostics will be a simple extension of those developed for the ERL test facility. In this paper we present a preliminary report on eCooling Diagnostics. We summarize the planned conventional Diagnostics, and follow with more detailed descriptions of Diagnostics specialized to the requirements of high-energy magnetized cooling.

CAMERON, P.; BEN-ZVI, I.; KEWISCH, J.; LITVINENKO, V.

2005-06-06

152

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

SciTech Connect

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

Budkin, G. V.; Tarasenko, S. A., E-mail: tarasenko@coherent.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2011-04-15

153

Multifrequency Doppler Radar Observations of Electron Gyroharmonic Effects during Electromagnetic Pumping of the Ionosphere  

Microsoft Academic Search

Experimental results of multifrequency HF Doppler radar studies during electromagnetic pumping of the ionosphere from the ground are reported. The Doppler shifts of the radar waves after turn-on of the vertically injected HF pump wave depend on the pump frequency and exhibit, at relatively large reflection altitudes, opposite signs for pump frequencies above or below an electron gyroharmonic. The results

S. Grach; G. Komrakov; M. Yurishchev; B. Thide; T. Leyser; T. Carozzi

1997-01-01

154

Study of harmonic generated by electromagnetic and electronic ballast used in street lighting  

Microsoft Academic Search

In this paper, several high power lighting networks based on high pressures sodium (HPS) lamps have been set up. These have been chosen because of they are used in public lighting. Both electromagnetic and electronic ballast have been used with the mentioned lamps. They have also been tested with different levels of power using dimming for a 220 V power

A. Gil-de-Castro; A. Moreno-Munoz; J. M. Flores Arias; V. Pallares-Lopez

2011-01-01

155

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

156

Diffusion of Electromagnetic Field into the Core of Inductor at Induction Accelerator of Electrons  

Microsoft Academic Search

Summary form only given. High energy electronic accelerator based on the inductive principle of particle interaction with accelerating field have used mostly the short pulses of voltage applied to each stage of accelerator. The typical width of pulse is concluded in the range 50... 250 nanoseconds. Such duration of electromagnetic process leads to necessity to use the magnetic material for

V. T. Chemerys; I. Borodiy

2007-01-01

157

Commissioning of Fermilab's Electron Cooling System for 8GeV Antiprotons  

Microsoft Academic Search

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

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

2005-01-01

158

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

Microsoft Academic Search

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

David L Bruhwiler

2005-01-01

159

A STRAIGHT SECTION DESIGN IN RHIC TO ALLOW HEAVY ION ELECTRON COOLING  

Microsoft Academic Search

The Relativistic Heavy Ion Collider (RHIC) has been continuously producing exciting results. One of the major luminosity limitations of the present collider is the intra beam scattering. A path towards the higher luminosities requires cooling of the heavy ion beams. Two projects in parallel electron and stochastic cooling are progressing very well. To allow interaction between electrons and the RHIC

D. Trbojevic; T. Roser; W. Mackay; J. Kewisch; S. Tepikian

2006-01-01

160

Reduced order modeling of power electronics cabinet with double-sided cooling  

Microsoft Academic Search

Thermal control of power electronics cabinets requires thermal characterization under multiple length scales and transport modes. Detailed numerical calculations or measurements are often time consuming or simply unfeasible. An efficient multiscale thermal modeling methodology is proposed for electronic cabinets with hybrid liquid, forced air convection, and thermoelectric cooling. Compact models are developed for complex components such as air-cooled heat sinks,

Qihong Nie; Yogendra Joshi

2008-01-01

161

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

162

Effects of trapped electrons on electromagnetic fields in an oblique shock wave  

SciTech Connect

A magnetosonic shock wave propagating obliquely to an external magnetic field can trap electrons and accelerate them to ultrarelativistic energies. The effect of trapped electrons on electromagnetic fields in a shock wave is studied by theory and particle simulations. The expressions for field strengths are analytically obtained, including the number of trapped electrons n{sub t} as a factor. It is shown that as n{sub t} increases, the magnitude of F increases, where F is the integral of the parallel electric field, E{sub ||}=(E{center_dot}B)/B, along B. Theoretical analysis also suggests that the increase in F causes the electrons to be trapped deeper and accelerated to higher kinetic energies. These theoretical predictions are verified with relativistic electromagnetic particle simulations.

Toida, Mieko; Shikii, Kenta [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

2009-11-15

163

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

164

Atomic systems with one and two active electrons in electromagnetic fields: Ionization and high harmonics generation  

NASA Astrophysics Data System (ADS)

We describe a theoretical procedure for solving the time-dependent Schrödinger equation (TDSE) for atomic systems with one or two valence electrons. Motion of the valence electrons is described by means of the Hartree-Fock potential including the exchange interaction. We apply the procedure to various physical phenomena occurring in atoms exposed to strong electromagnetic fields. As an illustration, we consider below the processes of high harmonics generation and attosecond pulses production.

Ivanov, I. A.; Kheifets, A. S.

2010-02-01

165

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

166

Status of the R&D Towards Electron Cooling of RHIC  

SciTech Connect

The physics interest in a luminosity upgrade of RHIC requires the development of a cooling-frontier facility. Detailed cooling calculations have been made to determine the efficacy of electron cooling of the stored RHIC beams. This has been followed by beam dynamics simulations to establish the feasibility of creating the necessary electron beam. Electron cooling of RHIC at collisions requires electron beam energy up to about 54 MeV at an average current of between 50 to 100 mA and a particularly bright electron beam. The accelerator chosen to generate this electron beam is a superconducting Energy Recovery Linac (ERL) with a superconducting RF gun with a laser-photocathode. An intensive experimental R&D program engages the various elements of the accelerator: Photocathodes of novel design, superconducting RF electron gun of a particularly high current and low emittance, a very high-current ERL cavity and a demonstration ERL using these components.

A. Favale; D. Holmes; J.J. Sredniawski; Hans Bluem; M.D. Cole; J. Rathke; T. Schultheiss; A.M.M. Todd; V.V. Parkhomchuk; V.B. Reva; J. Alduino; D.S. Barton; Dana Richard Beavis; I. Ben-Zvi; Michael Blaskiewicz; J.M. Brennan; Andrew Burrill; Rama Calaga; P. Cameron; X. Chang; K.A. Drees; A.V. Fedotov; W. Fischer; G. Ganetis; D.M. Gassner; J.G. Grimes; Hartmut Hahn; L.R. Hammons; A. Hershcovitch; H.C. Hseuh; D. Kayran; J. Kewisch; R.F. Lambiase; D.L. Lederle; Vladimir Litvinenko; C. Longo; W.W. MacKay; G.J. Mahler; G.T. McIntyre; W. Meng; B. Oerter; C. Pai; George Parzen; D. Pate; D. Phillips; S.R. Plate; Eduard Pozdeyev; Triveni Rao; J. Reich; Thomas Roser; A.G. Ruggiero; T. Russo; C. Schultheiss; Z. Segalov; J. Smedley; K. Smith; T. Tallerico; S. Tepikian; R. Than; R.J. Todd; Dejan Trbojevic; J.E. Tuozzolo; P. Wanderer; G. WANG; D. Weiss; Q. Wu; Kin Yip; A. Zaltsman; A. Burov; S. Nagaitsev; L.R. Prost; A.O. Sidorin; A.V. Smirnov; Yaroslav Derbenev; Peter Kneisel; John Mammosser; H. Phillips; Joseph Preble; Charles Reece; Robert Rimmer; Jeffrey Saunders; Mircea Stirbet; Haipeng Wang; A.V. Aleksandrov; D.L. Douglas; Y.W. Kang; D.T. Abell; G.I. Bell; David L. Bruhwiler; R. Busby; John R. Cary; D.A. Dimitrov; P. Messmer; Vahid Houston Ranjbar; D.S. Smithe; A.V. Sobol; P. Stoltz

2007-08-01

167

Comparison of Stimulated Electromagnetic Emissions from Long Time Langmuir and Upper Hybrid/Electron Bernstein Turbulence during Electromagnetic Pumping of the Ionospheric Plasma  

NASA Astrophysics Data System (ADS)

A powerful high frequency electromagnetic pump wave transmitted into the ionosphere from the ground excites plasma turbulence which causes electromagnetic radiation that can be detected on the ground. We report experimental results from using the EISCAT-Heating facility in Norway as the pump for the daytime ionospheric plasma, detection of the stimulated electromagnetic radiation, and probing of the Langmuir turbulence by the EISCAT-UHF and -VHF incoherent scatter radars. The long time scale frequency spectrum (several seconds integration time) of the radar scatter from near parallel to the geomagnetic field is compared to that of the stimulated electromagnetic emissions for different pump frequencies near the third electron gyro harmonic. It is found that the long time scale Langmuir turbulence which is strongly excited at the gyro harmonic as detected with the EISCAT-VHF radar does not cause significant electromagnetic radiation. This is contrary to the case of the upper hybrid/electron Bernstein turbulence excited at pump frequencies away from the gyro harmonic, which results in a rich spectrum of stimulated electromagnetic emissions. The experimental results appear to question our present understanding of the mechanisms for electromagnetic radiation from Langmuir turbulence.

Leyser, T. B.; Isham, B.; La Hoz, C.; Rietveld, M. T.; Hagfors, T.; Kofman, W.; Mishin, E.

2000-10-01

168

Medium energy electron cooling R and D at Fermilab -- Context and status  

SciTech Connect

Electron cooling at the proposed Recycler 8 GeV storage ring has been identified as a key element in exploiting the capacity of the Fermilab Main Injector for an additional factor of ten in Tevatron luminosity above the goal for the next collider run, ultimately to > 10{sup 33} cm{sup {minus}2}s{sup {minus}1}. The most basic requirement for increased luminosity is a large stack of antiprotons cooled to emittance comparable to that of the proton beam. Although electron cooling is inferior to the stochastic technique for cooling large emittance beams, its rate is practically independent of the antiproton intensity. For cooling intense beams of low or moderate emittance, electron cooling excels. The realization of electron cooling for 8 GeV antiprotons requires major extension of existing practice in electron energy and length of the cooling interaction region. It will require 4.3 MeV dc electron beam maintaining high quality and precise collinearity with the antiprotons over a 66 m straight section. The initial goal of the R and D project is 200 mA electron current in about three years; the plan is to reach 2 A over the following three years.

MacLachlan, J.A.

1996-05-01

169

Stimulated trapped electron acoustic wave scattering, electromagnetic soliton and ion vortices in intense laser interaction with subcritical plasmas  

SciTech Connect

Stimulated trapped electron acoustic wave scattering by a linearly polarized intense laser in a subcritical plasma is studied by particle simulation. The scattering process is a three-wave parametric decay of the laser pump into a critical Stokes electromagnetic sideband wave and the trapped electron acoustic wave. As the ion acoustic wave grows in time, it breaks locally, followed by a large relativistic electromagnetic soliton. A new phenomenon, MeV ion vortex in ion phase space, forms by local electromagnetic and electrostatic fields inside the soliton. It is found that the electron acoustic wave mode is similar to the kinetic electrostatic electron nonlinear waves.

Li Baiwen; Ishiguro, S.; Skoric, M. M.; Sato, T. [Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); Graduate University for Advanced Studies and National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Earth Simulator Center, JAMSTEC, 3173-25 Showa-cho, Yokohama-shi 236-0001 (Japan)

2007-03-15

170

Optimal Fan Arrangement for Electronic Equipment with Multi-Fan CoolingSystem including Air Cooled Heat Sink with Fan  

Microsoft Academic Search

Parametric study is conducted for optimizing the fan arrangement of the electronic equipment with several fans inthe equipment. Those fans are cooling for central processing unit (CPU), for power supply unit (PSU), and for the other devices in the equipment (system exhaust fan). We have used the Taguchi method of the experimental design for finding the optimal arrangement of those

Hitoshi Matsushima; Shuichi Terakado; Ichirou Asano

2009-01-01

171

Liquid cooling methods for power electronics in an automotive environment  

Microsoft Academic Search

This work compares the performance of “Liquid Pin” coolers and other advanced cooling techniques like “ShowerPower”, pin fin and microchannel. Water glycol mixture (40 % v\\/v glycol) is used as a cooling agent at temperatures of 5 °C, 20 °C, 40 °C and 60 °C. Various characteristics of the coolers like pressure drop, thermal resistance and impedance are examined.

M. Baumann; J. Lutz; W. Wondrak

2011-01-01

172

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

NASA Technical Reports Server (NTRS)

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

Levinson, Amir; Eichler, David

1992-01-01

173

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

174

Modulational instability of electromagnetic electron-cyclotron wave packets in the magnetosphere with non-Maxwellian electron distribution  

SciTech Connect

The satellite observations of the magnetosphere in the low-frequency ion dynamics revealed several facts: (1) localized structures for electric field signal parallel to the magnetic field; (2) anisotropy for the electron velocity distribution such that T{sub perpendicular}<electrons. Based on these evidences, a nonlinear model is presented to develop the electromagnetic electron-cyclotron (EMEC) theory to the non-Maxwellian plasmas. Then, the modulational instability analysis of EMEC waves is investigated.

Abbasi, H. [Faculty of Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Hakimi Pajouh, H. [Department of Physics, Alzahra University, Tehran 19834 (Iran, Islamic Republic of)

2008-09-15

175

Electromagnetic Instabilities, Filamentation, and Focusing of Relativistic Electron Beams  

Microsoft Academic Search

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

Roswell Lee; Martin Lampe

1973-01-01

176

Vibrational and rotational cooling of electrons by water vapor. [in cometary ionospheres  

NASA Technical Reports Server (NTRS)

The cooling of electrons by vibrational and rotational excitation of water molecules plays an important role in the thermal balance of electrons in cometary ionospheres. The energy-loss function for rotational excitation and deexcitation of H2O by electron impact is calculated theoretically. The rotational cooling rate is calculated using this loss function for a wide range of electron and neutral temperatures. The vibrational cooling rate is calculated using measured values of electron-impact vibrational excitation cross sections. Analytical formulas are provided for some of the cooling rates. The interaction of ions with H2O molecules is also discussed, and a formula is suggested for the momentum-transfer collision frequency.

Cravens, T. E.; Korosmezey, A.

1986-01-01

177

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

SciTech Connect

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

Hershcovitch, A.

2011-01-01

178

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

179

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

SciTech Connect

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

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

2001-10-11

180

Cryogenically cooled K-band high electron mobility transistor receiver for radio astronomical observation  

Microsoft Academic Search

A K-band receiver using cooled high electron mobility transistor (HEMT) amplifiers was developed at the Nobeyama Radio Observatory. A remarkable reduction in receiver noise temperature, T(rec), was obtained when it was cooled down to cryogenic temperature. The lowest T(rec) of 75 K was obtained at 23.4 GHz. This low noise characteristic reveals that the cooled HEMT amplifier is promising as

T. Kasuga; R. Kawabe; M. Ishiguro; K. Yamada; H. Kurihara; M. Niori; Y. Hirachi

1987-01-01

181

Cryogenically cooled K-band high electron mobility transistor receiver for radio astronomical observation  

NASA Astrophysics Data System (ADS)

A K-band receiver using cooled high electron mobility transistor (HEMT) amplifiers was developed at the Nobeyama Radio Observatory. A remarkable reduction in receiver noise temperature, T(rec), was obtained when it was cooled down to cryogenic temperature. The lowest T(rec) of 75 K was obtained at 23.4 GHz. This low noise characteristic reveals that the cooled HEMT amplifier is promising as a sensitive receiver for radio astronomical observations.

Kasuga, T.; Kawabe, R.; Ishiguro, M.; Yamada, K.; Kurihara, H.

1987-03-01

182

Smart pumpless loop for micro-channel electronic cooling using flat and enhanced surfaces  

Microsoft Academic Search

Two-phase cooling of a square simulated electronic device surface of 21.3 mm side was successfully carried out without the need for a pump. This smart, passive cooling system incorporates a self-enhancing and self-sustaining mechanism, wherein the system inherently enhances its cooling capacity by increasing the velocity of the two-phase mixture along the boiling surface when an increase in heat flux

Swaraj Mukherjee; Issam Mudawar

2003-01-01

183

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

184

A front-end electronics module for the PHENIX electromagnetic calorimeter  

Microsoft Academic Search

A front-end electronics module (FEM) has been developed for the PHENIX electromagnetic calorimeter. The FEM processes the signals received from each of 144 photomultiplier tubes and provides energy, timing and trigger information to the experiment's data collection and trigger systems. The FEM is designed to measure energies with a 14-bit dynamic range (approximately 1 MeV up to 16 GeV) with

A. L. Wintenberg; W. C. Allen; J. M. Branning; S. Q. Daniels; S. S. Frank; M. S. Musrock; D. E. Smith; P. W. Stankus; J. W. Walker; G. R. Young

1998-01-01

185

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

186

Electromagnetic ion cyclotron mode (ELF) waves generated by auroral electron precipitation  

Microsoft Academic Search

Narrow-banded ELF waves with frequencies between the local hydrogen and the singly-charged helium gyrofrequencies have been seen in the S3-3 satellite electric field wave data at altitudes between 800 and 8000 km. The waves are generated in or just below the auroral acceleration region by the accelerated electron beam and propagate in the Alfven-ion cyclotron branch of the cold electromagnetic

M. Temerin; R. L. Lysak

1984-01-01

187

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

National Technical Information Service (NTIS)

A new theoretical model is introduced to describe heterodyne mixer conversion efficiency and noise (from thermal fluctuation effects) in diffusion-cooled superconducting hot-electron bolometers. The model takes into account the non-uniform internal electr...

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

1998-01-01

188

Ultra-low-temperature cooling of two-dimensional electron gas  

NASA Astrophysics Data System (ADS)

A new design has been used for cooling GaAs/Al xGa 1- xAs sample to ultra-low-temperatures. The sample, with electrical contacts directly soldered to the sintered silver powder heat exchangers, was immersed in liquid 3He, which was cooled by a PrNI 5 nuclear refrigerator. The data analysis shows that the two-dimensional electron gas (2DEG) was cooled to 4.0 mK at the refrigerator base temperature Tb of 2.0 mK. The design with heat exchanger cooling is applicable to any ultra-low-temperature transport measurements of 2DEG system.

Xia, J. S.; Adams, E. D.; Shvarts, V.; Pan, W.; Stormer, H. L.; Tsui, D. C.

2000-05-01

189

Air cooling of front-end electronics for silicon detectors in a collider experiment  

NASA Astrophysics Data System (ADS)

We have investigated the feasibility of using room temperature air to cool front-end electronics for silicon microstrip and pad detectors in a collider experiment. Advantages of air cooling include minimal material in the path of the particles and no potential of coolant spills in the silicon region. A prototype cooling system was tested with heat provided by flat resistive heaters. Heat loads from 1 to 27 mW/channel were studied, making the results applicable to various silicon detector systems. The measurements are compared to cooling system performance predictions. A set of simple equations has been identified and tested which reliably describe the lab setup.

Lock, J. S.; Bertson, E.; Boissevain, J.; Clark, D. J.; Collier, W.; Hammock, R.; Jacak, B. V.; Morgan, A.; Roybal, P.; Shaheen, S.; Simon-Gillo, J.; Sullivan, J. P.

1994-06-01

190

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

191

Coupling of electrons to the electromagnetic field in a localized basis  

NASA Astrophysics Data System (ADS)

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.

Allen, Roland

2008-10-01

192

Coupling of electrons to the electromagnetic field in a localized basis  

NASA Astrophysics Data System (ADS)

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.

Allen, Roland E.

2008-08-01

193

Coupling of electrons to the electromagnetic field in a localized basis  

NASA Astrophysics Data System (ADS)

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.

Allen, Roland

2009-03-01

194

Materials selection for electronic enclosures in space environment considering electromagnetic interference effect  

NASA Astrophysics Data System (ADS)

Using low power electronic devices for space applications to reduce the mass and energy consumption has lead to electromagnetic interference (EMI) problem. Electronic enclosures are used to shield electronic devices against EMI. In the past, electromagnetic shielding has been mainly the only criteria considered in electronic enclosure design. However, there are several structural and thermal requirements for selection of shielding materials which should also be taken into account. In this research work, three quantitative materials selection methods, i.e. Digital Logic (DL), Modified Digital Logic (MDL), and Z-transformation, are employed to select the best material from among a list of candidate materials. Composite and metallic electronic enclosures are explored and the best material is selected. Z-transformation method is applicable to both of the considered case studies while DL and MDL can only be used for solving one of them. Z-transformation method ranks aluminum as the first choice among various metallic materials. The wide range of Z-transformation application and its practical results confirm the superiority of Z-transformation method over DL and MDL methods.

Fayazbakhsh, K.; Abedian, A.

2012-02-01

195

Combined Laser and Electron Cooling of Bunched C3+ Ion Beams at the Storage Ring ESR  

SciTech Connect

We report on first laser cooling studies of bunched beams of triply charged carbon ions stored at an energy of 1.46 GeV at the ESR (GSI). Despite for the high beam energy and charge state laser cooling provided a reduction of the momentum spread of one order of magnitude in space-charge dominated bunches as compared to electron cooling. For ion currents exceeding 10 {mu}A intra-beam-scattering losses could not be compensated by the narrow band laser system presently in use. Yet, no unexpected problems occurred encouraging the envisaged extension of the laser cooling to highly relativistic beams. At ESR, especially the combination with modest electron cooling provided three-dimensionally cold beams in the plasma parameter range of unity, where ordering effects can be expected and a still unexplained signal reduction of the Schottky signal is observed.

Schramm, U.; Bussmann, M.; Habs, D. [Department fuer Physik, LMU Muenchen, 85748 Garching (Germany); Kuehl, T.; Beller, P.; Franzke, B.; Nolden, F.; Steck, M. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Saathoff, G.; Reinhardt, S. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Karpuk, S. [Institut fuer Physik, Universitaet Mainz, Mainz (Germany)

2006-03-20

196

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

NASA Astrophysics Data System (ADS)

The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaska provides effective radiated powers in the megawatt range that have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. In recent HAARP heating experiments, it has been shown that during the Magnetized Stimulated Brillouin Scattering MSBS instability, the pumped electromagnetic wave may decay into an electromagnetic wave and a low frequency electrostatic wave (either ion acoustic IA wave or electrostatic ion cyclotron EIC wave). Using Stimulated Electromagnetic Emission (SEE) spectral features, side bands which extend above and below the pump frequency can yield significant diagnostics for the modified ionosphere. It has been shown that the IA wave frequency offsets can be used to measure electron temperature in the heated ionosphere and EIC wave offsets can be used as a sensitive method to determine the ion species by measuring ion mass using the ion gyro-frequency offset. The threshold of each emission line has been measured by changing the amplitude of pump wave. The experimental results aimed to show the threshold for transmitter power to excite IA wave propagating along the magnetic field lines as well as for EIC wave excited at an oblique angle relative to the background magnetic field. Another parametric decay instability studied is the ion Bernstein decay instability that has been attributed to the simultaneous parametric decay of electron Bernstein waves into multiple electron Bernstein and ion Bernstein waves. The SIB process is thought to involve mode conversion from EM to EB waves followed by parametric decay of the EB wave to multiple EB and IB waves. The parametric decay instability of ion Bernstein modes has been observed simultaneously for the first time at the third electron gyroharmonics during 2011 Summer Student Research Campaign SSRC at HAARP. The analytical results for the SIB waves at the 3rd and 4th gyroharmonics will be presented which shows good agreement with experimental data. The variation of Stimulated Electromagnetic Emission (SEE) spectrum during generation of the artificial plasma layer by HAARP transmitter has been studied during 2012 PARS campaign. It turns out that SEE features observed during the formation of artificial plasma layers may be used as a diagnostic tool to investigate the generation source of these artificial layers. Both experimental data and analytical results will be presented.

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

2012-12-01

197

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

198

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

SciTech Connect

The paper outlines features of the implicit hybrid simulation code ANTHEM, which uniquely provides histories for the transport and deposition of suprathermal and thermal electrons in laser-produced plasmas. The code models two-dimensional electron transport through steep density gradients and across contiguous collisional and collisionless target regions with the plasma dynamics dominated by self-consistent EPSILON and BETA fields. ANTHEM employs separate Eulerian fluid ion and thermal electron treatments and models suprathermal electrons as either a third fluid or as a set of collisional particle-in-cell (PIC) particles. The authors outline new techniques required to obtain implicit electromagnetic fields in two spatial dimensions permitting time steps well in excess of the local plasma period. A new implicit scattering model is discussed. The utility of our approach is demonstrated with sample applications to collisional surface transport on foil targets.

Mason, R.J.; Cranfill, C.W.

1986-02-01

199

Recycler Electron Cooling Project: Mechanical vibrations in the Pelletron and their effect on the beam  

SciTech Connect

The Fermilab's Recycler ring will employ an electron cooler to cool stored 8.9 GeV antiprotons [1]. The cooler is based on an electrostatic accelerator, Pelletron [2], working in an energy-recovery regime. A full-scale prototype of the cooler has been assembled and commissioned in a separate building [3]. The main goal of the experiments with the prototype was to demonstrate stable operation with a 3.5 MeV, 0.5 A DC electron beam while preserving a high beam quality in the cooling section. The quality is characterized, first of all, by a spread of electron velocities in the cooling section, which may be significantly affected by mechanical vibration of the Pelletron elements. This paper describes the results of vibration measurements in the Pelletron terminal and correlates them with the beam motion in the cooling section.

Kazakevich, Grigory M.; Burov, A.; Boffo, C.; Joireman, P.; Saewert, G.; Schmidt, C.W.; Shemyakin, A.; /Fermilab

2005-07-01

200

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

NASA Astrophysics Data System (ADS)

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 ? 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 (?/W) and (?/W)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.; Ang, L. K.; Koh, W. S.

2011-02-01

201

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

PubMed

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

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

2006-11-01

202

Comparison of Hybrid Electric Vehicle Power Electronics Cooling Options  

SciTech Connect

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

O'Keefe, M.; Bennion, K.

2008-01-01

203

An improved dispersion relation for parallel propagating electromagnetic waves in warm plasmas: Application to electron scattering  

NASA Astrophysics Data System (ADS)

An improved dispersion relation, with thermal corrections retained, for parallel propagating electromagnetic waves in a warm plasma is developed for both left?hand (L?) and right?hand (R?) polarized modes. Compared with the cold plasma dispersion relation, the derived dispersion relation is in much better agreement with the full hot plasma dispersion relation (including the wave growth rate). The pitch angle scattering rates of energetic electrons are compared between using cold and full dispersion relation. Significant differences are found when evaluating pitch angle scattering rate of MeV electron caused by He+ band waves in multiple ion plasmas. Due to He+ ion cyclotron absorption, the He+band electromagnetic ion cyclotron waves, which are able to resonate with MeV electrons (at large wave number), tend to be strongly suppressed. Less significant differences in scattering rate of electrons between using cold and hot dispersion relation are found in the case of L?mode waves in single H+ ion plasma and in the case of R?mode waves.

Chen, Lunjin; Thorne, Richard M.; Shprits, Yuri; Ni, Binbin

2013-05-01

204

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

205

Electron kinetic effects in atmosphere breakdown by an intense electromagnetic pulse.  

PubMed

A physical model is proposed for description of electron kinetics driven by a powerful electromagnetic pulse in the Earth's atmosphere. The model is based on a numerical solution to the Boltzmann kinetic equation for two groups of electrons. Slow electrons (with energies below a few keV) are described in a two-term approximation assuming a weak anisotropy of the electron distribution function. Fast electrons (with energies above a few keV) are described by a modified macroparticle method, taking into account the electron acceleration in the electric field, energy losses in the continuous deceleration approximation, and the multiple pitch angle scattering. The model is applied to a problem of the electric discharge in a nitrogen, which is preionized by an external gamma-ray source. It is shown that the runaway electrons have an important effect on the energy distribution of free electrons, and on the avalanche ionization rate. This mechanism might explain the observation of multiple lightning discharges observed in the Ivy-Mike thermonuclear test in the early 1950's. PMID:11970682

Solovyev, A A; Terekhin, V A; Tikhonchuk, V T; Altgilbers, L L

1999-12-01

206

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

207

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

208

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

209

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

210

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

NASA Astrophysics Data System (ADS)

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.; Uryupin, S. A.

2013-08-01

211

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

212

Liquid flow-through cooling of electronic modules  

Microsoft Academic Search

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

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

1994-01-01

213

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

214

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

215

Electron transitions and the spectrum of radiation emitted by an atom interacting with an ultrashort electromagnetic pulse  

Microsoft Academic Search

Electron transitions and the spectrum of radiation emitted by an atom interacting with an ultrashort electromagnetic pulse\\u000a are studied based on the sudden perturbation approximation. The excitation and ionization probabilities, the spectra of pulse\\u000a reradiation by the atom, and the reradiation cross sections are calculated. It is concluded that the reradiation of ultrashort\\u000a electromagnetic pulses by multielectron atoms is of

V. I. Matveev

2003-01-01

216

PM2D code simulation of electronic dynamics and electro-magnetic fields generation by ultra-short laser pulses interaction with matter  

Microsoft Academic Search

The results of numerical simulation of fast electrons motion and generated electro-magnetic fields at the picosecond pulse laser interaction with flat target are presented. The calculations were performed with PM2D code, where relativistic equation of electron motion joint with Maxwell equations is solved by particle method in cells. The efficiency of fast electrons energy conversion to the transverse electromagnetic wave

I. A. Litvinenko; V. A. Lykov

1997-01-01

217

Capacitive Electron Cooling in an Inductively Coupled Plasma Source/Capacitively Coupled Plasma Bias Reactor  

NASA Astrophysics Data System (ADS)

An electron cooling mechanism has been found in an inductively coupled plasma (ICP) source/capacitively coupled plasma (CCP) bias reactor. From the results of the measured electron energy probability function (EEPF), it was found that the temperature of low-energy electrons \\varepsilon < 5 eV decreased with electron density when the bias power exceeded 100 W. In the case of a high-density plasma with an electron density of around 1011/cm3, capacitive coupling is a cause of significant ion loss, and electron wall loss is also enhanced to maintain the flux balance. Because of this flux balance, the potential barrier that must be overcome by electrons in the sheath collapse phase decreases further. This change in potential barrier enhances the wall loss of low-energy electrons below 5 eV, and the effective electron temperature decreases with an increase in bias power.

Jun, Hyun-Su; Lee, Dong-Seok; Chang, Hong-Young

2013-10-01

218

Subnanosecond electron transport in a gas in the presence of polarized electromagnetic waves  

SciTech Connect

An ensemble of free electrons in a classical Boltzmann gas under equilibrium condition follow a square law for the number of collisions suffered during random walk, in the elastic limit [N{proportional_to}({lambda}/{lambda}){sup 2}]. This study reveals for the first time that in the same limit the dependence is considerably modified in the presence of linearly polarized electromagnetic waves. The phenomenon happens at time scales shorter ({approx}10{sup -10} s) than the characteristic discharge initiation time and the wave period. Considering the actual dependence of collision cross-sections on electron energy, a new relation is obtained, which tends to the classical result for the zero field case. The random walk parameter <{chi}{sup 2}> characterizes a true versus constrained random process. The implications of the new relation describing the phenomena are discussed in the light of applications.

Dey, Indranuj; Mathew, Jose V.; Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Jain, Sachin [Institute of Physics, Bhubaneswar 751005 (India)

2008-04-15

219

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

220

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

221

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

222

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

NASA Astrophysics Data System (ADS)

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

Green, Michael A.

2003-12-01

223

A numerical study of free convection cooling of electronic equipment  

NASA Astrophysics Data System (ADS)

A numerical analysis of free convection from electronic components on PWB placed horizontally in the cabinets is described. The effects of aspect ratio H/L (H is the height of cabinet, L is length of it), dimensionless heat conductance of cabinet walls and baffle plate located at open side of cabinets on the free convection heat transfer in the cabinets were numerically investigated using finite difference method. It was clarified that the overall heat transfer coefficient was about 20% lower than that of an upward facing heated plate placed horizontally in semi-infinite space, and the streamline patterns obtained by present numerical analysis were in good agreement with the flow patterns visualized in the previous experiments.

Miyamoto, M.; Katoh, Y.; Sakata, M.

1985-10-01

224

Quasi-Optical THz Mixer Based on a Nb Diffusion-Cooled Hot-Electron Bolometer.  

National Technical Information Service (NTIS)

This thesis describes the development of a diffusion-cooled quasi-optical Nb hot electron bolometer mixer (HEBM). This development is driven by the need for a sensitive heterodyne detector with a large IF bandwidth that will find its use in astronomical a...

W. Ganzevles

2003-01-01

225

Simulation aided design of a two-phase thermosyphon for power electronics cooling  

Microsoft Academic Search

In this paper we present a novel system for power electronics cooling consisting of a thermosyphon loop composed of an evaporator, to which the power modules are attached, and of a condenser, formed by a set of vertically mounted aluminum panels. To facilitate the optimization of the design of the condenser, which is critical for the whole system performance, we

Francesco Agostini; Thomas Gradinger; Carlo de Falco

2011-01-01

226

Use of Flow Network Modeling (FNM) for Enhancing the Design Process of Electronic Cooling Systems  

Microsoft Academic Search

This paper outlines the technique of Flow Network Modeling (FNM) for system-level thermal design of electronic devices. FNM is a generalized methodology involving representation of a cooling system as a network of components and flow paths for predicting systemwide distribution of flow rates, pressures, and temperatures. Performance of the individual components in the network is specified by overall flow and

Kanchan M. Kelkar; Amir Radmehr; Patrick J. Kelly; Suhas V. Patankar; Christian Belady

227

High Energy Electron Cooling to Improve the Luminosity and Lifetime in Colliding Beam Machines.  

National Technical Information Service (NTIS)

Electron cooling can be applied to improve the performance of high energy colliding beams of hadrons and e exp - p storage rings. Normal beam excitations such as multiple scattering, resonance growth, or beam--beam interaction can be controlled, leading t...

D. Cline A. Garren H. Herr F. E. Mills C. Rubbia

1979-01-01

228

SBIR Phase II Project, ParSEC - Parallel Simulation of Electron Cooling.  

National Technical Information Service (NTIS)

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). Located at Brookhaven National Laboratory (BNL), RHIC is the premier nuclear phy...

D. Bruhwiler

2005-01-01

229

Boiling Heat Transfer Enhancement Using Micro-Machined Porous Channels for Electronics Cooling  

Microsoft Academic Search

Boiling heat transfer enhancement for a passive electronics cooling design is presented in this paper. A novel pool boiling enhancement technique is developed and characterized. A combination of surface modification by metallic coating and micro-machined porous channels attached to the modified surface is tested and reported. An experimental rig is set up using a standard BGA package with 12 mm

Navas Khan; K. C. Toh; D. Pinjala

2008-01-01

230

2.3-Ghz Cryogenically Cooled HEMT (High Electron Mobility Transistor) Amplifier for DSS 13.  

National Technical Information Service (NTIS)

A prototype 2.3 GHz (S band) high electron mobility transistor (HEMT) amplifier/closed cycle refrigerator (CCR) system was installed in the DDS-13 feedcone, replacing the 2.3 GHz maser. The amplifier is cryogenically cooled to a physical temperature of 12...

L. Tanida

1987-01-01

231

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

SciTech Connect

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

Istomin, Ya. N. [P. N. Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation)] [P. N. Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Leyser, T. B. [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)] [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)

2013-05-15

232

High-Coherence Electron and Ion Bunches from Laser-Cooled Atoms  

NASA Astrophysics Data System (ADS)

Cold atom electron and ion sources produce electron bunches and ion beams by photoionisation of laser cooled atoms. They offer high coherence and the potential for high brightness, with applications including ultrafast electron diffractive imaging of dynamic processes at the nanoscale. Here we present our cold atom electron/ion source, with an electron temperature of less than 10 K and a transverse coherence length of 10 nm. We also discuss experiments investigating space-charge effects with ions and the production of ultra-fast electron bunches using a femto-second laser. In the latter experiment we show that it is possible to produce both cold and fast electron bunches with our source.

McCulloch, A. J.; Sheludko, D. V.; Putkunz, C. T.; Saliba, S. D.; Thompson, D. J.; Speirs, R. W.; Murphy, D.; Torrance, J.; Sparkes, B. M.; Scholten, R. E.

2014-04-01

233

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

234

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

235

Interplay of electrostatic and electromagnetic instabilities for relativistic electron beams in a plasma  

NASA Astrophysics Data System (ADS)

The physics of relativistic electron particle beams propagating through the plasma is of a significant interest for laboratory astrophysics, fast ignition, and Z-pinch research. Most attention has been directed towards the analysis of electromagnetic filamentation instabilities. On the other hand, there exists a broad class of very powerful electrostatic instabilities, e.g., the Buneman instability. The author considers in a unified fashion linear theory for both types of instabilities under conditions where there is no magnetic field in an unperturbed state (i.e., the beam current is fully neutralized by the plasma current). The following factors are taken into account: the beam energy and angular spread; plasma non-uniformity; particle collisions in the background plasma. The areas of the parameter domain where particular instability is prevalent are identified; the results are presented in the form of several easy-to-use diagrams. Prepared by LLNL under contract DE-AC52-07NA27344.

Ryutov, D. D.

2008-11-01

236

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

SciTech Connect

We 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 features. 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. Wiggle-plane focusing is produced by curved pole tips. The magnitude of random pole-to-pole field errors is minimized by a mechanical design concept that reduces tolerance stackup in critical locations. To date, we have tested 15 m of this wiggler, and our measurements have shown exceptionally low levels of random errors. 8 refs.

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

1987-01-01

237

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

238

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

239

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

240

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

241

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

242

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

243

Susceptibility of electronic equipment by electromagnetic fields simulated with a novel measurement technique based on conducted threats  

Microsoft Academic Search

Electronic circuits are of vital importance for the function of traffic systems, security systems and modern communication. A malfunction in one of these areas may cause casualties and economic disasters. Taken the aspect of electromagnetic terrorism into account a system with fast rise time tr and short pulse length tfwhm could be a very dangerous weapon, because it can be

M. Camp; R. Herschmann; H. Garbe

244

Parametric upward conversion of the electromagnetic wave frequency in a relativistic electron flux drifting in a magnetized plasma  

NASA Astrophysics Data System (ADS)

The paper is concerned with the combined effect of a plasma and of a magnetic field on the parametric interaction of two transverse electromagnetic waves with the space charge wave of a relativistic electron flux. It is shown that absolute instability is possible in such a system in addition to convective instability; the instability can be stabilized by selecting approximate parameters. The plasma existing in the drift region of the relativistic electron beam increases the amplification coefficient.

Draganov, A. B.; Kalmykov, A. M.

1985-12-01

245

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

246

Computational analysis of electron phonon cooling for a high-temperature superconductor terahertz thermal sensor  

NASA Astrophysics Data System (ADS)

The mathematical treatment of the time-dependent heat transfer differential equations, involving electron-phonon (e-p) cooling in the sensor film and phonon-phonon cooling in the sensor-substrate system, has been developed in an earlier paper (Kaila M M 2002 J. Supercond. 15 185). In this paper, the effect of the e-p coupling, in particular with reference to responsivity and conversion gain, is studied. This is done with reference to a typical high-temperature superconductor hot electron heterodyne receiver. An analysis is presented related to the effects of e-p coupling and the phonon specific heat in particular, in the form of three-dimensional graphics.

Kaila, M. M.

2004-01-01

247

Gap-reduced thermal paste package design for cooling single flip-chip electronic modules  

Microsoft Academic Search

A method of reducing the thermal paste chip-to-cap interface gap is presented to achieve enhanced cooling of single flip-chip electronic modules. The structure and assembly process steps of the gap reduction design are described. The thermal reliability of the design is evaluated by measuring the thermal resistance for several permutations of the structural design variables, allowing identification of an optimum

K. K. Sikka; H. T. Toy; D. L. Edwards; S. Iruvanti; E. M. Ingalls; P. W. DeHaven

2002-01-01

248

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

Microsoft Academic Search

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

Kambiz Vafai; Lu Zhu

1999-01-01

249

Numerical algorithms for modeling electron cooling in the presence of external fields  

Microsoft Academic Search

The design of the high-energy cooler for the Relativistic Heavy Ion Collider (RHIC) recently adopted a nonmagnetized approach. To prevent recombination between the fully stripped gold ions and co-propagating electrons, a helical undulator magnet has been proposed. In addition, to counteract space-charge defocusing, weak solenoids are proposed every 10 m. To understand the effect of these magnets on the cooling

G. I. Bell; D. L. Bruhwiler; A. Sobol; I. Ben-Zvi; A. Fedotov; V. Litvinenko

2007-01-01

250

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

SciTech Connect

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

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

2012-07-01

251

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

252

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

253

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

PubMed

The scheme of an internal injection of Au atoms into the working space of the "Krion-2" electron string ion source (ESIS) was applied and tested. In this scheme Au atoms are evaporated from the thin tungsten wire surface in vicinity of the source electron string. Ion beams with charge states up to Au51+ were produced. Ion-ion cooling with use of C and O coolant ions was studied. It allowed increasing of the Au51+ ion yield by a factor of 2. Ions of Kr up to charge state 28+ were also produced in the source. Electron strings were first formed with injection electron energy up to 6 keV. Methods to increase the ESIS ion output are discussed. PMID:19566200

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

2009-06-01

254

Large Bandwidth and Low Noise in a Diffusion-Cooled Hot-Electron Bolometer Mixer  

NASA Technical Reports Server (NTRS)

Heterodyne measurements have been made at 533 GHz using a novel superconducting hot-electron bolometer in a waveguide mixer. The bolometer is a 0.3 micrometer long niobium microbridge with a superconducting transition temperature of 5 K. The short length ensures that electron diffusion dominates over electron-phonon interactions as the electron cooling mechanism, which should allow heterodyne detection with intermediate frequencies (if) of several GHz. A Y-factor response of 1.15 dB has been obtained at an if of 1.4 GHz with 77 and 295 K loads, indicating a receiver noise temperature of 650 K DSB. The -3 dB rolloff in the if response occurs at 1.7 GHz.

Skalare, A.; McGrath, W. R.; Bumble, B.; LeDuc, H. G.; Burke, P. J.; Verheijen, A. A.; Schoelkopf, R. J.; Prober, D. E.

1996-01-01

255

Electron magnetic resonance of ferrofluids: Evidence for anisotropic resonance at 77 K in samples cooled in a magnetic field  

NASA Astrophysics Data System (ADS)

Evidence is presented from studies of electron magnetic resonance for the formation of linear chains in kerosene based Mn 0.1Fe 0.9Fe 2O 4 (MF1) ferrite ferrofluid cooled in a magnetic field. The resonance field at 77 K was found to depend on the field at which the sample was cooled. More interestingly, the samples cooled in a magnetic field exhibited anisotropy in a resonance field with 180° periodicity, giving evidence for frozen chains.

Sastry, M. D.; Babu, Y.; Goyal, P. S.; Mehta, R. V.; Upadhyay, R. V.; Srinivas, D.

1995-08-01

256

Smart, low-cost, pumpless loop for micro-channel electronic cooling using flat and enhanced surfaces  

Microsoft Academic Search

Two-phase cooling of a square simulated electronic device surface of 21.3 mm side was successfully carried out without the need for a pump. This smart, passive, low-cost cooling system incorporates a self-enhancing and self-sustaining mechanism, wherein the system inherently enhances its cooling capacity by increasing the velocity of the two-phase mixture along the boiling surface when an increase in heat

Swaraj Mukherjee; Issam Mudawar

2002-01-01

257

Polarization effect on the Raman backscattering of an electromagnetic wave propagating through an electron-positron-ion magnetoplasma  

NASA Astrophysics Data System (ADS)

The present study is devoted to the investigation of stimulated Raman backscattering of an intense, circularly polarized electromagnetic wave in magnetized electron-positron-ion plasma. The nonlinear dispersion relation as well as the growth rate of instability is achieved. The effects of external magnetic field, fraction of electron-positron pairs, pump frequency and also the kind of polarization on the growth rate is studied. It is shown that an admixture of e-p pairs to the ion-electron plasma modifies the behavior of plasma with respect to the external magnetic field.

Sepehri Javan, N.; Maraghechi, B.; Nemati Siahmazgi, R.

2013-12-01

258

Foil Cooling for the Rep-Rated Electron Beam Pumped Electra Laser  

NASA Astrophysics Data System (ADS)

The Electra program at the Naval Research Laboratory is developing the science and technologies for implementation of krypton-fluoride (KrF) lasers in inertial fusion energy. Large aperture KrF lasers are pumped by electron beams which transit a foil separating the gas target at >=1 atm pressure from the vacuum diode. A fraction of the beam energy is deposited in the foil and thus long term (>=10^8 shots), rep-rated (5 Hz) operation requires active cooling of the foil to prevent thermal yield relaxation and cycling fatigue. This paper will report on experimental data and theoretical analysis of two diverse approaches to foil thermal management: convective and conductive cooling. Convective turbulent cooling has been operational on the Electra main amp through the use of oscillating louvers within a gas recirculator containing the pumped lasing region. At 5 Hz the foil temperature (Tf) can be maintained at ˜400 ^oC for a 1 mil SS foil. Conduction cooling provides the simplest configuration with only the need for water channels in the ribs of the hibachi. For a 1 mil Al foil, Tf is predicted to be ˜140 ^oC at 5 Hz. Comparison of experimental and theoretical results and advanced foil materials will be discussed.

Giuliani, J. L.; Hegeler, F.; Wolford, M. F.; Abdel-Khalik, S.

2005-10-01

259

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

Microsoft Academic Search

We present what we believe is a new class of composite electromagnetic materials characterized by the concept of metamorphism, which we define in general terms. Metamorphic materials exhibit bulk electromagnetic transitions among states characterized by distinct ranges of values of their reflection coefficient. Each such state has unique physical properties induced by the corresponding values of the reflection coefficient. We

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

2006-01-01

260

Effect of electromagnetic ion cyclotron wave normal angle distribution on relativistic electron scattering in outer radiation belt  

Microsoft Academic Search

We present the equatorial and bounce-averaged pitch angle diffusion coefficients for the scattering relativistic electrons by He +-mode electromagnetic ion cyclotron waves. Both the model (prescribed) and self-consistent distributions over the wave normal angle are considered. The main results of our calculation can be summarized as follows: First, in comparison with field-aligned waves, intermediate and highly oblique waves decrease the

G. V. Khazanov; K. V. Gamayunov

2007-01-01

261

Effect of electromagnetic ion cyclotron wave normal angle distribution on relativistic electron scattering in outer radiation belt  

Microsoft Academic Search

We present the equatorial and bounce-averaged pitch angle diffusion coefficients for the scattering relativistic electrons by He+-mode electromagnetic ion cyclotron waves. Both the model (prescribed) and self-consistent distributions over the wave normal angle are considered. The main results of our calculation can be summarized as follows: First, in comparison with field-aligned waves, intermediate and highly oblique waves decrease the bounce-averaged

G. V. Khazanov; K. V. Gamayunov

2007-01-01

262

Self-similar modes of amplification and compression of electromagnetic pulses in their interaction with electron flows  

NASA Astrophysics Data System (ADS)

Self-similar solutions describing the amplification and compression of ultrashort electromagnetic pulses in their interaction with quasi-stationary electron flows are constructed on the basis of analogy with the coherent amplification of short optical pulses by inverted laser media. It is shown that the effects of amplification of pulses with their simultaneous compression are universal and must be observed for different mechanisms of induced radiation, including the Cherenkov and cyclotron mechanisms.

Ryskin, N. M.; Ginsburg, N. S.; Zotova, I. V.

2013-05-01

263

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

264

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

265

Razdelenie ehlektronov i adronov v yacheistom ehlektromagnitnom kalorimetre tipa sehdwich svinets-stsintillyator. (Electron and hadron discrimination in cell electromagnetic calorimeter of lead-scintillator sandwich type).  

National Technical Information Service (NTIS)

Additional light-guide-shifter which collects light only from scintillation plates arranged in maximum of electromagnetic shower is suggested to use to improve efficiency of electron and hadron separation in the module of hodoscopic detector GEPARD. Using...

Y. Ivanyushkin E. Kistenev V. M. Kubik Y. Pishchal'nikov A. G. Kholodenko

1988-01-01

266

About the role of the surface scattering of electrons on the effect of electromagnetic generation of sound (in English)  

NASA Astrophysics Data System (ADS)

A system consisting of sandwich structure: a halfspace (a dielectric or a conductor medium) and N-1 conductor films of thickness d is considered. A recursive relation for the sound wave amplitude in the case of specular reflection of the conduction electrons is derived. The dependence of the amplitude of the sound field as a function of the number of conductor films is studied. A numerical analysis about the role of the surface scattering of electrons on the effect of electromagnetic generation of sound is performed.

Galbova, O.; Ivanovski, G.

267

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

NASA Astrophysics Data System (ADS)

Gurevich et al. [1] postulated that the source of narrow bipolar pulses, a class of high energy pulses that occur during thunderstorms, could be a runaway electron avalanche driven by the intense electric fields of a thunderstorm. Recently, Watson and Marshall [2] used the modified transmission line model to test the mechanism of the source of narrow bipolar pulses. In a recent paper, Cooray and Cooray [3] demonstrated that the electromagnetic fields of accelerating charges could be used to evaluate the electromagnetic fields from electrical discharges if the temporal and spatial variation of the charges in the discharge is known. In the present study, those equations were utilized to evaluate the electromagnetic fields generated by a relativistic electron avalanche. In the analysis it is assumed that all the electrons in the avalanche are moving with the same speed. In other words, the growth or the decay of the number of electrons takes place only at the head of the avalanche. It is shown that the radiation is emanating only from the head of the avalanche where electrons are being accelerated. It is also shown that an analytical expression for the radiation field of the avalanche at any distance can be written directly in terms of the e-folding length of the avalanche. This makes it possible to extract directly the spatial variation of the e-folding length of the avalanche from the measured radiation fields. In the study this model avalanche was used to investigate whether it can be used to describe the measured electromagnetic fields of narrow bipolar pulses. The results obtained are in reasonable agreement with the two station data of Eack [4] for speeds of propagation around (2 - 2.5) x 10^8 m/s and when the propagation effects on the electric fields measured at the distant station is taken into account. [1] Gurevich et al. (2004), Phys. Lett. A., 329, pp. 348 -361. [2] Watson, S. S. and T. C. Marshall (2007), Geophys. Res. Lett., Vol. 34, L04816, doi: 10.1029/2006GL027426. [3] Cooray, V. and G. Cooray (2010), IEEE Transactions on Electromagnetic Compatibility, 52, No. 4, 944 - 955. [4] Eack, K. B. (2004), Geophys. Res. Lett., Vol. 31, L20102, doi: 10.1029/2005GL023975.

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

2011-12-01

268

Electron energy relaxation dynamics in GaAs quantum wells grown on Si: cool-hole effect  

NASA Astrophysics Data System (ADS)

Cool hole effect on hot electron energy relaxation dynamics in GaAs quantum wells grown on Si was investigated using photoreflectance and time-resolved photoluminescence spectroscopies. It was demonstrated that for the quantum wells in which there is a two- dimensional light (heavy) mass hole gas the electron energy relaxation is dominated by electron-hole (electron-longitudinal optical phonon) energy exchange.

Shum, Kai; Takiguchi, Yoshihiro; Mohaidat, Jihad M.; Alfano, Robert R.; Qiang, Hao; Pollak, Fred H.; Morkoc, Hadis

1992-10-01

269

Simulations of Electromagnetic Ion Cyclotron Waves and Their Effect on Ring Current Protons and Radiation Belt Electrons  

NASA Astrophysics Data System (ADS)

Using a two-dimensional hybrid code (particle ions and inertialess fluid electrons) in dipole geometry, we investigate the evolution of electromagnetic ion cyclotron waves and their effect on ring current protons and radiation belt electrons. Ion populations simulated include anisotropic ring current protons with perpendicular temperature greater than parallel temperature, and cold protons, helium ions, and oxygen ions. The waves are excited in the vicinity of the magnetic equator, and the dominant wave mode is the He+ wave band that asymptotes to the He+ gyrofrequency at large parallel component of the wave vector. The evolution of the ring current proton distribution can be followed during the entire simulation including precipitation loss to the ionosphere. Relativistic electrons are inserted into the simulation at various times to see how these particles are affected by the waves. Our calculations suggest that the pitch angle scattering and precipitation loss of relativistic electrons due to these waves is stronger than was previously thought.

Denton, R. E.

2013-12-01

270

To the theory of induced scattering of electromagnetic waves by an electron beam in a regular waveguide  

NASA Astrophysics Data System (ADS)

In this work, a formula for the amplification parameter (analogous to the Pierce parameter in travelling-wave tube theory) of regular waveguide modes is deduced in the case of induced scattering by an electron beam with an arbitrary electron density distribution in the cross section. The presence of an axial magnetic field transporting a beam along the interaction region is taken into account. Obtained results can be used for calculation of the amplification in free electron lasers with electromagnetic, magnetostatic or electrostatic pump and a definite beam transverse profile. In particular, expressions for amplification coefficients in the case of a thin-wall hollow electron beam propagating in a cylindrical waveguide, that takes into account the excitation of beam waves (space charge in TWT theory), are found. An analysis of the dependence of amplification on the guiding magnetic field value and hollow beam radius is carried out.

Karbushev, N. I.; Shatkus, A. D.

1991-07-01

271

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

272

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

273

Low-temperature two-phase micro-channel cooling for high-heat-flux thermal management of defense electronics  

Microsoft Academic Search

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

Jaeseon Lee; Issam Mudawar

2008-01-01

274

Dynamics of electronic transitions and reemission spectra of attosecond electromagnetic pulses  

NASA Astrophysics Data System (ADS)

The processes of reemission of attosecond electromagnetic pulses by systems in nonstationary states have been considered. The probabilities of the reemission of attosecond electromagnetic pulses at the resonance charge exchange of a proton on a hydrogen atom and at the decay of a quasistationary state, as well as the probabilities of the reemission of attosecond pulses by a system in a resonance external field, have been calculated as examples. The developed method can be applied to more complex targets, including targets in the collision state, and to various chemical reactions.

Matveev, V. I.; Makarov, D. N.

2014-05-01

275

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

SciTech Connect

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

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

2005-07-15

276

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

277

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

278

Electromagnetic environmental effects compendium  

NASA Astrophysics Data System (ADS)

This report summarizes the electromagnetic environmental effects (E3) program of the U.S. Army Communications-Electronics Command (CECOM). The report includes background information on CECOM's role in the Army E3 program, presents the approach used to identify the electromagnetic environment, summarizes E3 criteria (i.e., the CECOM model electromagnetic environment), and provides a sample E3 assessment. The report also discusses electromagnetic trends and their implications.

Brockel, Kenneth H.; Cofield, David; Deallaume, William; Gorr, Lanny; Major, Paul A.

1993-08-01

279

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

SciTech Connect

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

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

2005-11-01

280

Reduction of the friction force in electron cooling systems due to magnetic field errors  

NASA Astrophysics Data System (ADS)

Magnetic field errors can limit the dynamical friction force on co-propagating ions and, hence, increase the cooling time. We present theoretical and numerical results for reduction of the friction force due to bounded transverse magnetic field errors, as a function of wavelength. VORPAL [1] simulations using a binary collision algorithm [2] show that small-wavelength field errors affect the friction logarithmically, via the Coulomb log, while long-wavelength errors reduce the friction by effectively increasing the transverse electron temperature. A complete understanding of finite-time effects and the role of small impact parameter collisions is required to correctly interpret the simulation results. We show that the distribution of electron-ion impact parameters is similar to a Pareto distribution, for which the central limit theorem does not apply. A new code has been developed to calculate the cumulative distribution function of electron-ion impact parameters and thus correctly estimate the expectation value and uncertainty of the friction force. [1] C. Nieter and J. Cary, J. Comp. Phys. 196 (2004), p. 448. [2] G. Bell et al., J. Comp. Phys. 227 (2008), p. 8714.

Sobol, Andrey; Bell, George; Bruhwiler, David; Fedotov, Alexei; Litvinenko, Vladimir

2009-05-01

281

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

NASA Astrophysics Data System (ADS)

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

Solmeyer, Neal

282

The Nonlinear Absorption Coefficient of a Strong Electromagnetic Wave by Confined Electrons in Quantum Wells Under the Influences of Confined Phonons  

Microsoft Academic Search

The nonlinear absorption coefficient (NAC) of a strong electromagnetic wave (EMW) by confined electrons in quantum wells under the influences of confined phonons is theoretically studied by using the quantum transport equation for electrons. In comparison with the case of unconfined phonons, the dependence of the NAC on the energy (??), the amplitude (Eo) of external strong EMW, the width

N. Q. Bau; L. T. Hung; N. D. Nam

2010-01-01

283

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

284

Electromagnetic simulation of electronic packaging designs (95ERP003). 1995 LDRD final report  

Microsoft Academic Search

The primary focus of the project summarized in this report has been to evaluate the performance of the 3D, time-domain electromagnetic code DS13D in the simulation of structures used in microwave microelectronics circuits. We`ve adopted two test cases, coaxial and stripline transmission lines, for which well-known results are available so that results obtained with DS13D could be easily and accurately

Swegle

1996-01-01

285

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

286

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

NASA Astrophysics Data System (ADS)

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.

Kazinski, P. O.

2013-12-01

287

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

288

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

289

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

290

Kuehlung von Elektronischen Geraeten in Kampfflugzeugen (Cooling of Electronic Equipment in Fighter Aircraft).  

National Technical Information Service (NTIS)

Cooling systems for avionics purposes are discussed. The design and test requirements for the continuous and intermittent operation of equipment, and the sensitivity of avionics to cooling air temperature are discussed. Climatic conditions in aircraft and...

W. Senoner

1986-01-01

291

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

Microsoft Academic Search

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

Jaeseon Lee; Issam Mudawar

2009-01-01

292

Effect of Heating and Cooling of Photogenerated Electron--Hole Plasma in Optically Pumped Graphene on Population Inversion  

Microsoft Academic Search

We study the characteristics of photogenerated electron--hole plasma in optically pumped graphene layers at elevated (room) temperatures when the interband and intraband processes of emission and absorption of optical phonons play a crucial role. The electron--hole plasma heating and cooling as well as the effect of nonequilibrium optical phonons are taken into account. The dependences of the quasi-Fermi energy and

Victor Ryzhii; Maxim Ryzhii; Vladimir Mitin; Akira Satou; Taiichi Otsuji

2011-01-01

293

Conversion gain and fluctuation noise of phonon-cooled hot-electron bolometers in hot-spot regime  

Microsoft Academic Search

In this paper, a one-dimensional heat balance model for the hot-spot length of phonon-cooled hot-electron bolometer is set up and solved for the electron temperature profile along the bolometer bridge. A self-consistent theoretical method is presented to obtain the hot-spot length profile as a function of RF and bias heating power. This result is used to predict current-voltage characteristics. For

Harald F. Merkel; Pourya Khosropanah; Danny Wilms Floet; Pavel A. Yagoubov; Erik L. Kollberg

2000-01-01

294

8.4-GHz Cryogenically Cooled HEMT (High Electron Mobility Transistor) Amplifier for DSS (Deep Space Station) 13.  

National Technical Information Service (NTIS)

A prototype 8.4 GHz (X-band) high electron mobility transistor (HEMT) amplifier/closed cycle refrigerator system was installed in the Deep Space Station 13 feedcone in August 1987. The amplifier is cryogenically cooled to a physical temperature of 12 K an...

L. Tanida

1988-01-01

295

Production Techniques for the PALADIN Free-Electron Laser Wiggler Magnets.  

National Technical Information Service (NTIS)

More than 3000 high-quality, strip-wound, edge-cooled electromagnets for the PALADIN free-electron laser (FEL) experiment at the LLNL Advanced Test Accelerator (ATA) have been fabricated. Close attention to tooling, semiautomated techniques, and selective...

A. R. Harvey R. W. Johnson M. E. Morrison

1987-01-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

297

One dimensional electromagnetic simulation of multiple electron beams propagating in space plasmas  

Microsoft Academic Search

It is by now well known that electron beams play an important role in generating radio emissions such as type II and type III radio bursts, commonly observed by spacecraft in the interplanetary medium. Electron beams streaming back from Earth's bow shock into the solar wind have been proposed as a possible source for the electron plasma waves observed by

Fernando Simões Junior; Maria Virgínia Alves

2010-01-01

298

One-dimenssional electromagnetic simulation of multiple electron beams propagating in space plasmas  

Microsoft Academic Search

It is by now well known that electron beams play an important role in generating radio emissions such as type II and type III radio bursts, commonly observed by spacecraft in the interplanetary medium. Electron beams streaming back from Earth's bow shock into the solar wind have been proposed as a possible source for the electron plasma waves observed by

F. J. R. Simões; M. V. Alves; R. Gaelzer

2010-01-01

299

Electromagnetic simulation of electronic packaging designs (95-ERP-003). 1995 LDRD final report  

SciTech Connect

The primary focus of the project summarized in this report has been to evaluate the performance of the 3D, time-domain electromagnetic code DS13D in the simulation of structures used in microwave microelectronics circuits. We`ve adopted two test cases, coaxial and stripline transmission lines, for which well-known results are available so that results obtained with DS13D could be easily and accurately checked. Our goals have been three-fold: (1) To develop specialized mode-launching capabilities for single-mode signals typically found in test geometries and the diagnostics necessary to evaluate the performance of the code in modeling the propagation of those signals. (2) To analyze the effect of different zoning schemes on the accuracy with which the code models the propagation of signals through the geometries by checking against known analytic results and calculations performed with other codes. (3) To examine the effect of code modifications aimed at enhancing the accuracy of the simulations. The calculated transmission line impedance was chosen as the primary means of evaluating code performance. Since the lowest-order propagating modes for the test cases were transverse electromagnetic (TEM) modes, the computation of impedance was reasonably straightforward. Both time- and frequency-domain values (the latter obtained from the code output by post-processing with a discrete Fourier transform) were obtained and compared.

Swegle, J.A.

1996-05-01

300

Fe XXI Emission Line Ratios as Electron Temperature Diagnostics for the Coronae of Cool Stars  

NASA Astrophysics Data System (ADS)

Theoretical Fe xxi electron temperature and density sensitive emission line ratios are presented for R_1 = Ileft( {2s^2 2p^2 {}^3P_1 - 2s2p^3 {}^5S} right)/Ileft( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } right) and R_2 = Tleft( {2s^2 2p^2 {}^3P_1 - 2s2p^2 {}^1S} right)/Tleft( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } right) . A comparison of these with observational data for the 1973 December 17 solar flare, obtained by the Naval Research Laboratory's S082A and S082B spectrographs on board Skylab, reveals reasonably good agreement between theory and observation for R 1[= I(242.07 mathop ? limits^c)/I(1354.08 Å)], which provides some support for the accuracy of the atomic data adopted in the line ratio calculations. However, our results for R 2 indicate that the emission feature in flare spectra at 338.06 Å, previously identified as the Fe xxi 2s 22p 2 3 p 1 - 2s 22p 2 1 S line, is not due to this species but may be the Ca v 3p 4 3 p 1 - 3p 33d 3 P 2 transition. The potential of using R 1 as an electron temperature diagnostic for the Fe xxi line emitting regions of cool star coronae, through a combination of Extreme Ultraviolet Explorer and Hubble Space Telescope observations, is briefly discussed.

Keenan, F. P.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G.

1996-11-01

301

Sorption cooling: A valid extension to passive cooling  

Microsoft Academic Search

Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into

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

2008-01-01

302

Sorption cooling: a valid extension to passive cooling  

Microsoft Academic Search

Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into

Jan Doornink; Johannes Burger; Marcel ter Brake

2007-01-01

303

Self-induced transparency and electromagnetic pulse compression in a plasma or an electron beam under cyclotron resonance conditions.  

PubMed

Based on analogy to the well-known process of the self-induced transparency of an optical pulse propagating through a passive two-level medium we describe similar effects for a microwave pulse interacting with a cold plasma or rectilinear electron beam under cyclotron resonance condition. It is shown that with increasing amplitude and duration of an incident pulse the linear cyclotron absorption is replaced by the self-induced transparency when the pulse propagates without damping. In fact, the initial pulse decomposes to one or several solitons with amplitude and duration defined by its velocity. In a certain parameter range, the single soliton formation is accompanied by significant compression of the initial electromagnetic pulse. We suggest using the effect of self-compression for producing multigigawatt picosecond microwave pulses. PMID:21231673

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

2010-12-31

304

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

305

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

SciTech Connect

The physics and numerics of the hybrid electron transport code ANTHEM are described. The need for the hybrid modeling of laser generated electron transport is outlined, and a general overview of the hybrid implementation in ANTHEM is provided. ANTHEM treats the background ions and electrons in a laser target as coupled fluid components moving relative to a fixed Eulerian mesh. The laser converts cold electrons to an additional hot electron component which evolves on the mesh as either a third coupled fluid or as a set of Monte Carlo PIC particles. The fluids and particles move in two-dimensions through electric and magnetic fields calculated via the Implicit Moment method. The hot electrons are coupled to the background thermal electrons by Coulomb drag, and both the hot and cold electrons undergo Rutherford scattering against the ion background. Subtleties of the implicit E- and B-field solutions, the coupled hydrodynamics, and large time step Monte Carlo particle scattering are discussed. Sample applications are presented.

Mason, R.J.; Cranfill, C.W.

1985-01-01

306

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

307

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

SciTech Connect

The average number of collisions N of seed electrons with neutral gas atoms during random walk in escaping from a given volume, in the presence of polarized electromagnetic waves, is found to vary as N=B({lambda}/{lambda}){sup 2}/[1+C({lambda}/{lambda})]{sup 2}, indicating a modification to the conventional field free square law N=A({lambda}/{lambda}){sup 2}, where {lambda} is the characteristic diffusion length and {lambda} the mean free path. It is found that for the field free case A=1.5 if all the electrons originate at the center and is 1.25 if they are allowed to originate at any random point in the given volume. The B and C coefficients depend on the wave electric field and frequency. Predictions of true discharge initiation time {tau}{sub c} can be made from the temporal evolution of seed electrons over a wide range of collision frequencies. For linearly polarized waves of 2.45 GHz and electric field in the range (0.6-1.0)x10{sup 5} V/m, {tau}{sub c}=5.5-1.6 ns for an unmagnetized microwave driven discharge at 1 Torr argon.

Bhattacharjee, Sudeep; Paul, Samit [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

2009-10-15

308

Changes in mitochondrial functioning with electromagnetic radiation of ultra high frequency as revealed by electron paramagnetic resonance methods.  

PubMed

Abstract Purpose: To study the effects of electromagnetic radiation (EMR) of ultra high frequency (UHF) in the doses equivalent to the maximal permitted energy load for the staffs of the radar stations on the biochemical processes that occur in the cell organelles. Materials and methods: Liver, cardiac and aorta tissues from the male rats exposed to non-thermal UHF EMR in pulsed and continuous modes were studied during 28 days after the irradiation by the electron paramagnetic resonance (EPR) methods including a spin trapping of superoxide radicals. Results: The qualitative and quantitative disturbances in electron transport chain (ETC) of mitochondria are registered. A formation of the iron-nitrosyl complexes of nitric oxide (NO) radicals with the iron-sulphide (FeS) proteins, the decreased activity of FeS-protein N2 of NADH-ubiquinone oxidoreductase complex and flavo-ubisemiquinone growth combined with the increased rates of superoxide production are obtained. Conclusions: (i) Abnormalities in the mitochondrial ETC of liver and aorta cells are more pronounced for animals radiated in a pulsed mode; (ii) the alterations in the functioning of the mitochondrial ETC cause increase of superoxide radicals generation rate in all samples, formation of cellular hypoxia, and intensification of the oxide-initiated metabolic changes; and (iii) electron paramagnetic resonance methods could be used to track the qualitative and quantitative changes in the mitochondrial ETC caused by the UHF EMR. PMID:24597749

Burlaka, Anatoly; Selyuk, Marina; Gafurov, Marat; Lukin, Sergei; Potaskalova, Viktoria; Sidorik, Evgeny

2014-05-01

309

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

310

Electromagnetic analogies to general-Hamiltonian effective-mass electron wave propagation in semiconductors with spatially varying effective mass and potential energy  

Microsoft Academic Search

It is shown that exact, quantitative electromagnetic analogies exist for all forms of the general Hamiltonian [R. A. Morrow and K. R. Brownstein, Phys. Rev. B 30, 678 (1984)], which applies to single-band effective-mass electron wave propagation in semiconductors. It is further shown that these analogies are valid for propagation in the bulk, propagation past abrupt interfaces between materials, and

Gregory N. Henderson; Thomas K. Gaylord; Elias N. Glytsis

1992-01-01

311

FEM Electromagnetic Analysis and Thermal-Fluid Dynamics Analysis of Gaseous He Cooling For the Capacitive Tuner of The ITER ICRH Antenna  

Microsoft Academic Search

The object of the present work has been a preliminary design of the Helium cooling system for the capacitive tuning system of nuclear fusion reactor antennas. The use of Helium, instead of water, avoids the risk of serious problems if the cooling circuit would break, but the cooling process results to be less efficient. The finite element code ANSYS has

Francesca Cau; Pietro Testoni; Giuseppe Bosia; Piergiorgio Sonato

312

Electromagnetic Radiation: On Trial  

NSDL National Science Digital Library

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

313

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

National Technical Information Service (NTIS)

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 auto...

S. V. Narumanchi V. Hassani D. Bharathan

2005-01-01

314

Coupling of transient ultra wide band electro-magnetic fields to complex electronic systems  

Microsoft Academic Search

In this paper the coupling of transient ultra wide band field pulses to complex electronic systems is determined. Different test setups of microcontroller circuits were used to investigate the coupling effects and to describe the injected interference parameters.

M. Camp; H. Garbe; F. Sabath

2005-01-01

315

The quenching field effect on the motion of an electron in an electromagnetic field potential  

NASA Astrophysics Data System (ADS)

In this paper, the Feynman path integral approach based on the Gaussian wave packet approximation is employed to evaluate the coherence factor and the probability distribution for a single electron subjected to a magnetic field tailored by a variable on/off force. The quenching field effect is observed to create decoherence in the motion of the electron. The coherence factor is observed to decrease while the distribution probability function shows dephasing characteristics for weak and strong field strengths.

Fouokeng, Georges Collince; Tchoffo, Martin; Fai, Lukong Cornelius; Afuoti, Ngwa Engelbert; Kuetche, J. C. Ngana; Nouaze, A. M. Temgoua

2014-03-01

316

Effective source of sharp focused electromagnetic radiation of electrons with moderate relativistic energy  

Microsoft Academic Search

The new circulation scheme of intense bremsstrahlung source with a sharp directed flow of X-ray and gamma-photons is proposed. In traditional sources the summary output, due to notable self-absorption of generated photon in target, makes no more than 1\\/3 from all radiative electron losses. Besides because of strong electron scattering in the target material, the photon radiation happens in an

V. Grishint; S. Likhachev

2003-01-01

317

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

318

BRIEF COMMUNICATIONS: Calculation of the energy characteristics of a pulse-periodic electron-beam-controlled CO2 laser with a cooled active mixture  

Microsoft Academic Search

The optimal excitation conditions and energy characteristics are calculated for a pulse-periodic electron-beam-controlled CO2 laser with a cooled active mixture. A comparison is made with the characteristics of electron-beam-controlled lasers operating at room temperature. It is shown that cryogenic cooling of the active mixture enables the average output power of pulse-periodic industrial electron-beam-controlled CO2 lasers to be increased by a

E. P. Glotov; V. A. Danilychev; N. N. Sazhina; A. M. Soroka; N. V. Cheburkin

1982-01-01

319

A self-tuning electromagnetic vibration absorber with adaptive shunt electronics  

NASA Astrophysics Data System (ADS)

Tuned vibration absorbers (TVAs) are effective devices for vibration control in the presence of tonal excitation, but when the properties of the host structure change or the excitation frequency varies they become detuned and their performance can degrade to an unacceptable level. It is therefore desirable that the properties of the TVA can adapt to maintain optimal tuning. In this paper an electromagnetic device with an adaptive synthetic shunt impedance which provides a controllable effective mechanical stiffness and damping is proposed. The shunt impedance, comprising resistance and capacitance, is implemented digitally and can be altered in real-time to allow the system to adapt. A model-based feedforward controller is designed and implemented to adapt both the shunt resistance and capacitance to ensure the tuned frequency of the vibration absorber tracks the excitation frequency. This ensures that the system has optimal performance throughout a large range of excitation frequencies. Simulations and experimental results show that the adaptive controller can successfully adapt the system to track a variable excitation frequency and hence demonstrates better performance than the equivalent non-adaptive undamped system, as well as an optimally tuned damped system.

McDaid, A. J.; Mace, B. R.

2013-10-01

320

Blazar synchrotron emission of instantaneously power-law injected electrons under linear synchrotron, non-linear SSC, and combined synchrotron-SSC cooling  

NASA Astrophysics Data System (ADS)

Context. The broadband spectral energy distributions (SED) of blazars show two distinct components which in leptonic models are associated with synchrotron and synchrotron self-Compton (SSC) emission of highly relativistic electrons. In some sources the SSC component dominates the synchrotron peak by one or more orders of magnitude implying that the electrons mainly cool by inverse Compton collisions with their self-made synchrotron photons. Therefore, the linear synchrotron loss of electrons, which is normally invoked in emission models, has to be replaced by a nonlinear loss rate depending on an energy integral of the electron distribution. This modified electron cooling changes significantly the emerging radiation spectra. Aims: It is the purpose of this work to apply this new cooling scenario to relativistic power-law distributed electrons, which are injected instantaneously into the jet. Methods: We assume a spherical, uniform, nonthermal source, where the distribution of the electrons is spatially and temporally isotropic throughout the source. We will first solve the differential equation of the volume-averaged differential number density of the electrons, and then discuss their temporal evolution. Since any non-linear cooling will turn into linear cooling after some time, we also calculated the electron number density for a combined cooling scenario consisting of both the linear and non-linear cooling. For all cases, we will also calculate analytically the emerging optically thin time-integrated synchrotron intensity spectrum, also named the fluence, and compare it to a numerical solution. Results: The first result is that the combined cooling scenario depends critically on the value of the injection parameter ?0. For values ?0 ? 1 the electrons cool mainly linear, while in the opposite case the cooling begins non-linear and becomes linear for later times. Secondly, in all cased we find that for small normalized frequencies f < 1 the fluence spectra F(f) exhibit power-laws with constant spectral indices F(f) f-\\vartheta. We find for purely linear cooling \\vartheta_SYN = 1/2, and for purely non-linear cooling \\vartheta_SSC = 3/2. In the combined cooling scenario we obtain for the small injection parameter \\vartheta_1 = 1/2, and for the large injection parameter \\vartheta_2 = 3/2, which becomes \\vartheta_1 = 1/2 for very small frequencies. These identical behaviors, as compared to the existing calculations for monoenergetically injected electrons, prove that the spectral behavior of the total synchrotron fluence is independent from the functional form of the energy injection spectrum. Appendices are only available in electronic form at http://www.aanda.org

Zacharias, M.; Schlickeiser, R.

2010-12-01

321

Single and Multiple Volume Reflections of Ultra-Relativistic Electrons in a Bent Crystal as Tools for Intense Production of Electromagnetic Radiation  

NASA Astrophysics Data System (ADS)

Electromagnetic radiation emitted by ultrarelativistic volume-reflected and multi-volume-reflected electrons in a bent crystal is very intense and takes place over a broad angular range of the incident beam. Such radiation results to be nearly independent from the particles trajectory and charge. This paper describes the possible applications these features allow, from the production of a gamma or a positron source to the crystal-assisted collimation of future linear e+/e? colliders and crystal-based electromagnetic calorimeters.

Bandiera, L.; Mazzolari, A.; Bagli, E.; Berra, A.; Lietti, D.; De Salvador, D.; Guidi, V.; Prest, M.; Tikhomirov, V.; Vallazza, E.

2014-05-01

322

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

Microsoft Academic Search

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

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

1997-01-01

323

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

PubMed

Research and development on advanced high heat flux cooling technology for electronic devices has been carried out as the Project of Fundamental Technology Development for Energy Conservation, promoted by the New Energy and Industrial Technology Development Organization of Japan (NEDO). Based on the microgravity experiments on boiling heat transfer, the following useful results have obtained for the cooling of electronic devices. In subcooled flow boiling in a small channel, heat flux increases considerably more than the ordinary critical heat flux with microbubble emission in transition boiling, and dry out of the heating surface is disturbed. Successful enhancement of heat transfer is achieved by a capillary effect from grooved surface dual subchannels on the liquid supply. The critical heat flux increases 30-40 percent more than for ordinary subchannels. A self-wetting mechanism has been proposed, following investigation of bubble behavior in pool boiling of binary mixtures under microgravity. Ideas and a new concept have been proposed for the design of future cooling system in power electronics. PMID:15644356

Suzuki, Koichi; Kawamura, Hiroshi

2004-11-01

324

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

Microsoft Academic Search

The dissociation pathways of HeH+ 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

H. B. Pedersen; L. Lammich; C. Domesle; B. Jordon-Thaden; O. Heber; J. Ullrich; R. Treusch; N. Guerassimova; A. Wolf

2010-01-01

325

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

Microsoft Academic Search

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

H. B. Pedersen; L. Lammich; C. Domesle; B. Jordon-Thaden; J. Ullrich; A. Wolf; O. Heber; R. Treusch; N. Guerassimova

2010-01-01

326

Advanced fillers for electronics encapsulation and electro-magnetic compatibility (EMC)  

Microsoft Academic Search

EMC self-shielding in electronics packaging has become possible with the use of specially configured Ferro-silicate powder, which is a by-product from another process. Present transfer moulded microelectronics packages dominate the packaging of the multi-billion semiconductor devices manufactured annually. These make use primarily of epoxy thermosets which are compounded with compatible inorganic particle \\

Nihal Sinnadurai

2006-01-01

327

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

328

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

329

Syllabus Enhancement for Electromagnetic Course in Biomedical Electronics Engineering at Universiti Malaysia Perlis  

Microsoft Academic Search

Biomedical engineering has evolved over the years until now virtually all engineering disciplines are engaged in “the application\\u000a of engineering principles to problems of the life sciences”. Universiti Malaysia Perlis (UniMAP) is one of the public higher\\u000a learning institutions in Malaysia that offer Biomedical Electronics Engineering at the undergraduate level. One of the core\\u000a subjects in this program is Biomedical

Aisyah Hartini Jahidin; N. F. Mohd Nasir; M. S. A. Megat Ali; A. F. Mohd Salleh; N. Mustafa; A. Saidatul; Z. Zakaria

330

Electron wave-packet dynamics in a relativistic electromagnetic field: 3-D analytical approximation  

Microsoft Academic Search

A solution to the Klein Gordon equation for a laser-driven electron is constructed from a superposition of Volkov states. The time-and space-dependent three-dimensional superposition integral can be evaluated analytically for an initial Gaussian momentum distribution when the expression for relativistic energy is expanded in a Taylor series over the scaled initial momenta. The solution preserves many complicated wave-packet dynamics in

J. Peatross; C. Müller; C. H. Keitel

2007-01-01

331

Gyroresonant acceleration of electrons in the magnetosphere by superluminous electromagnetic waves  

Microsoft Academic Search

Superluminous auroral kilometric radiation originates in the auroral cavity of the Earth's magnetosphere as right-hand extraordinary (R-X) mode emissions, with additional contributions from the left-hand ordinary (L-O) and left-hand extraordinary (L-X) modes. The three modes can propagate into the outer radiation belt and undergo gyroresonant interaction with trapped energetic electrons over a broad extent of the outer magnetosphere. We develop

Danny Summers; Richard M. Thorne; Fuliang Xiao

2001-01-01

332

Noise Temperature and IF Bandwidth of a 530 GHz Heterodyne Receiver Employing a Diffusion-Cooled Superconducting Hot-Electron Mixer.  

National Technical Information Service (NTIS)

We report on the first heterodyne measurements with a diffusion-cooled hot-electron bolometer mixer in the submillimeter wave band, using a waveguide mixer cooled to 2.2 K. The best receiver noise temperature at a local oscillator frequency of 533 GHz and...

A. Skalare W. R. McGrath B. Bumble H. G. LeDuc P. J. Burke A. A. Verheijen D. E. Prober

1995-01-01

333

High current magnetized plasma discharges and electron beams for capture and cooling of charged leptons and hadrons  

SciTech Connect

Nowadays most magnetic lenses used to capture and to focus pions and muons utilize azimuthal magnetic fields generated by large axial currents, like horns or lithium rods (or even a Z-pinch at GSI). Capture and focusing angle is proportional to the product of the current and length of the lens. State-of-the-art for these lenses is no more than 750 kA and 70 cm. A meter long, multi-MA, magnetized axial discharges were generated by the early days of fusion. Lenses based of such devices can increase the capture angle of pions, e.g., by more than a factor of 2. Electron beam cooling is presently achieved in storage rings by having charged particles interact with a co-moving electron beam. In these devices, typical parameters are electron beam currents of about 1 A, an interaction length of about 1 meter, and interaction time of about 30 msec. Multi-MA electron beams can be used for single-pass final stage cooling in a number of machines. Calculations for some applications, as well as other advantages indicate that these schemes deserve further more serious consideration.

Hershcovitch, A.

1997-07-01

334

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

335

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

National Technical Information Service (NTIS)

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 h...

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

1999-01-01

336

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

337

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

338

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

National Technical Information Service (NTIS)

The Department of Defense has many systems that can benefit from the features of a cm-scale microrefrigerator. We are developing for DARPA a cm- scale Micro-Stirling Active Cooling Module (MS/ACM) microrefrigerator to benefit the DoD systems. Under a DARP...

D. S. Beck

2012-01-01

339

Analyzing the Processes of Excitation and Decay of Plasma Turbulence near the Fifth Electron Gyroharmonic using Stimulated Electromagnetic Emission of the Ionosphere  

Microsoft Academic Search

We present the results concerning the dynamics of stimulated electromagnetic emission (SEE) in the vicinity of the 5th electron gyroharmonic in the ionospheric-modification experiment. Measurements of the dynamic characteristics of different SEE features were performed at the “Sura” heating facility (Radiophysical Research Institute (NIRFI), Nizhny Novgorod) with the use of specialized equipment of the Swedish Institute of Space Physics, Uppsala Division

E. N. Sergeev; S. M. Grach; G. P. Komrakov; B. Thidé; T. B. Leyser; T. D. Carozzi; M. Holz

2002-01-01

340

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

NASA Astrophysics Data System (ADS)

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.; Huang, S. J.; Wang, J. X.; Wang, P. X.

2012-05-01

341

Fluid flow and heat transfer in liquid cooled foam heat sinks for electronic packages  

Microsoft Academic Search

In this paper, the fluid flow and heat transfer of liquid cooled foam heat sinks (FHSs) were experimentally investigated. Eight Open-celled copper foam materials with two pore densities of 60 and 100 PPI (pores per inch) and four porosities varying from 0.6 to 0.9 were bonded onto copper base plates to form the FHSs, which were then assembled on flip

H. Y. Zhang; D. Pinjala; Yogendra K. Joshi; T. N. Wong; K. C. Toh; M. K. Iyer

2005-01-01

342

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

343

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

NASA Astrophysics Data System (ADS)

We present a modified Bitter-type electromagnet which features high magnetic field, fine electronic properties and efficient heat removal. The electromagnet is constructed from a stack of copper layers separated by mica layers that have the same shape. A distinctive design of cooling channels on the insulating layers and the parallel ducts between the layers ensures low resistance for cooling water to flow. A continuous current control system is also made to regulate the current through the electromagnet. In our experiment, versatile electromagnets are applied to generate magnetic field and gradient field. From our measurements, a peak magnetic field of 1000 G and a peak gradient field of 80 G/cm are generated in the center of the apparatuses which are 7 cm and 5 cm away from the edge of each electromagnet with a current of 230 A and 120 A, respectively. With the effective feedback design in the current control system and cooling water flow of 3.8 l/min, the stability of the current through the electromagnets can reach 10-5.

Luan, Tian; Zhou, Tianwei; Chen, Xuzong; Ma, Zhaoyuan

2014-02-01

344

Electromagnetic Modeling of Display Module Interconnect  

Microsoft Academic Search

This paper deals with the use of the computational electromagnetic modeling into the electromagnetic design (EMD) of an electronic system as apart of design process. In this paper an electric and electromagnetic computational verification flow is suggested. As an application electromagnetic modeling of interconnect of display module is investigated using suggested the EMD computational verification flow

A. N. Arslan; V. Hurskainen; I. Pankinaho; I. Kelander; A. Rautio

2006-01-01

345

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

NSDL National Science Digital Library

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 usin

Murphy, Maureen K.

2010-07-01

346

CFD ANALYSIS IN A HEAT SINK FOR COOLING OF ELECTRONIC DEVICES  

Microsoft Academic Search

The reliability of electronic components is affected critically by the temperature at which the junction operates. As operating powers and speed increase, and as designers are forced to reduce overall system dimensions, the problems of extracting heat and controlling temperature can become crucial. The continuing increase of power densities in electronics packages and the simultaneous drive to reduce the size

347

A two-dimensional hot-spot mixer model for phonon-cooled hot electron bolometers  

Microsoft Academic Search

A hot spot model for superconducting hot electron bolometers is presented based on a two-dimensional heat transport equation for electrons and phonons including heat trapping due to quasiparticle bandgap gradients. Skin effect concentrates the RF heating in lateral regions of the bridge and the bias current in the center. A reduction in conversion gain compared to a one-dimensional hot spot

Harald F. Merkel; Pourya Khosropanah; Serguei Cherednichenko; K. S. Yngvesson; A. Adam; E. I. Kollberg

2001-01-01

348

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

349

Forced convective air cooling from electronic component arrays in a parallel plate channel  

NASA Astrophysics Data System (ADS)

This paper discusses air forced convection heat transfer from inline protruding elements arranged in eight rows. The streamwise and spanwise spacings between elements were varied using a splitter plate that can be positioned at three different modular configurations. A set of empirical formulas was presented to correlate the experimental data for the design of air cooling systems. Arrays of components with one odd- size module have been tested also. Experimental results show that blocks near the entrance and behind the odd- size module have improved performance compared with uniform arrangements. Accordingly, temperature sensitive components are suggested to be arranged in these locations.

Cai, D. Y.; Gan, Y. P.; Ma, C. F.; Li, Q. X.

1994-09-01

350

Desenvolvimento e simulacao computacional de bombas eletromagneticas termoeletricas para o controle do escoamento em reatores nucleares espaciais refrigerados a metal liquido. (Development and computational simulation of thermoelectric electromagnetic pumps for controlling the fluid flow in liquid metal cooled space nuclear reactors).  

National Technical Information Service (NTIS)

Thermoelectric Electromagnetic (TEEM) Pumps can be used for controlling the fluid flow in the primary and secondary circuits of liquid metal cooled space nuclear reactor. In order to simulate and to evaluate the pumps performance, in steady-state, the com...

E. M. Borges

1991-01-01

351

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

SciTech Connect

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

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

2004-11-01

352

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

SciTech Connect

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

MacLachlan, J. [ed.

1997-09-01

353

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Radiatively and tunnel-coupled surface electromagnetic waves in metal — dielectric structures  

NASA Astrophysics Data System (ADS)

The surface electromagnetic modes in five-layer metal — dielectric structures are investigated by a numerical computational method. The existence of two types of plasmon modes — radiatively and tunnel-coupled — is demonstrated. The mode type is determined by the specific geometry of the structure. The results of estimates of the effective refractive index of the plasmon leaky mode excited in an asymmetric three-layer metal — dielectric structure, are presented. The optical transparency effect, arising on excitation of the tunnel-coupled surface electromagnetic waves, is demonstrated experimentally.

Lyndin, N. M.; Svetikov, V. V.; Sychugov, V. A.; Usievich, B. A.; Yakovlev, V. A.

1999-09-01

354

32-GHz Cryogenically Cooled HEMT (High Electron Mobility Transitor) Low-Noise Amplifiers.  

National Technical Information Service (NTIS)

The cryogenic noise temperature performance of a two-stage and a three-stage 32 GHz High Electron Mobility Transistor (HEMT) amplifier was evaluated. The amplifiers employ 0.25 micrometer conventional AlGaAs/GaAs HEMT devices, hybrid matching input and ou...

J. J. Bautista G. G. Ortiz K. H. G. Duh W. F. Kopp P. Ho

1988-01-01

355

Physical Temperature of the Active Region in Cryogenically Cooled Indium Phosphide High-Electron Mobility Transistors  

Microsoft Academic Search

This article describes an experiment to measure the physical temperature of the active region of indium phosphide high-electron mobility transistors (HEMTs) while varying the chip temperature from 15 K to 50 K. The Pospieszalski HEMT device noise model predicts that the device noise temperature is dependent on the square root of the device-gate physical temperature. For this experiment the three-

J. J. Bautista; E. M. Long

2007-01-01

356

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

NASA Astrophysics Data System (ADS)

An experimental and analytical investigation of the steady-state thermal-hydraulic operating characteristics of a small-scale two-phase thermosiphon cooling actual power electronics are presented. Boiling heat transfer coefficients and circulation mass velocities were measured while varying heat load and pressure. Both a plain and augmented riser structure, utilizing micro-fins and reentrant cavities, were simultaneously tested. The boiling heat transfer coefficients increased with both increasing heat load and pressure. The mass velocity increased with increasing pressure while both increasing and then decreasing with increasing heat load. The reentrant cavity enhancement factor, a ratio of the augmented-to-plain riser nucleate boiling heat transfer coefficients, ranged from 1 to 1.4. High-speed photography revealed bubbly, slug, churn, wispy-annular and annular flow patterns. The experimental mass velocity and heat transfer coefficient data were compared to an analytical model with average absolute deviations of 16.3 and 26.3 percent, respectively.

Schrage, D. S.

1990-01-01

357

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

NASA Technical Reports Server (NTRS)

Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.

Loredo, Thomas J.; Lamb, Don Q.

1989-01-01

358

Experimental investigation of the ionospheric hysteresis effect on the threshold excitation level of the Stimulated Electromagnetic Emission (SEE) during heating at the second electron gyro-harmonic frequency  

NASA Astrophysics Data System (ADS)

Recent experimental observations of the stimulated electromagnetic emission (SEE) spectrum during heating at the second electron gyro-harmonic show structures ordered by ion gyro-frequency. The proposed generation mechanism considers parametric decay of a pump upper hybrid/electron Bernstein (UH/EB) wave into another UH/EB and a group of neutralized ion Bernstein waves. The presumption of the proposed mechanism is that the pump electromagnetic wave is converted into the UH/EB wave. This conversion process generates field aligned irregularity which exhibits hysteresis effect. The predicted ionospheric hysteresis effect is studied during the PARS 2012 at HAARP. The preliminary results are presented for the first time. Also, experimental study of the effects of 1) the transmitter beam angle and 2) the transmitter frequency offset relative to the second electron gyro-harmonic frequency on the ion gyro-harmonic structures in the SEE spectrum are provided. The aforementioned observations are compared to the predictions of the analytical model. Possible connection of the SEE spectral features and artificially generated ionospheric descending layer is also discussed

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

2012-12-01

359

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

360

Development of a Strong Electromagnet Wiggler.  

National Technical Information Service (NTIS)

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 magne...

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

1987-01-01

361

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

362

Visible spectroscopy of jet-cooled SiC2: Geometry and electronic structure  

Microsoft Academic Search

SiC2 has been prepared in a supersonic molecular beam by laser vaporization of a silicon carbide rod within a pulsed supersonic nozzle. Rotational analysis of the 0-0 band of the well-known 4980 A? band system of this molecule reveals that, contrary to previous assumptions, the molecule is triangular in both the ground and excited electronic states. In both states the

D. L. Michalopoulos; M. E. Geusic; P. R. R. Langridge-Smith; R. E. Smalley

1984-01-01

363

Neutrino signal of electron-capture supernovae from core collapse to cooling.  

PubMed

An 8.8M{?} electron-capture supernova was simulated in spherical symmetry consistently from collapse through explosion to essentially complete deleptonization of the forming neutron star. The evolution time (?9??s) is short because high-density effects suppress our neutrino opacities. After a short phase of accretion-enhanced luminosities (?200??ms), luminosity equipartition among all species becomes almost perfect and the spectra of ?{e} and ?{?,?} very similar, ruling out the neutrino-driven wind as r-process site. We also discuss consequences for neutrino flavor oscillations. PMID:20867357

Hüdepohl, L; Müller, B; Janka, H-T; Marek, A; Raffelt, G G

2010-06-25

364

Physical Temperature of the Active Region in Cryogenically Cooled Indium Phosphide High-Electron Mobility Transistors  

NASA Astrophysics Data System (ADS)

This article describes an experiment to measure the physical temperature of the active region of indium phosphide high-electron mobility transistors (HEMTs) while varying the chip temperature from 15 K to 50 K. The Pospieszalski HEMT device noise model predicts that the device noise temperature is dependent on the square root of the device-gate physical temperature. For this experiment the three-terminal HEMT device was separated into 2 two-terminal devices. One device was used as a heating element while the other served as a temperature-sensing element. The results indicate that the active device region is close to the chip ambient temperature.

Bautista, J. J.; Long, E. M.

2007-08-01

365

The recent and prospective developments of cooled IR FPAs for double application at Electron NRI  

NASA Astrophysics Data System (ADS)

xThe recent and prospective developments of monolithic silicon IR-Schottky-barrier staring focal plane arrays (IR SB FPAs), photodetector assembly, and digital thermal imaging cameras (TICs) at Electron National Research Institute (Electron NRI) are considered. Basic parameters for IR SB FPAs with 256x256 and 512x512 pixels, and TICs based on these arrays are presented. The problems emerged while proceeding from the developments of IR SB FPAs for the wavelength range from 3 ?m to 5 ?m to the developments of those ones for xLWIR range are indicated (an abrupt increase in the level of background architecture). Possibility for further improvement in basic parameters of IR SB FPAs are discussed (a decrease in threshold signal power down to 0.5÷1.0"1013 W/element with an increase in quantum efficiency, a decrease in output noise and proceeding to Schottky barriers of degenerated semiconductor/silicon heterojunction, and implementation of these array parameters in photodetector assembly with improved thermal background shielding taking into consideration an optical structure of TIC for concrete application). It is concluded that relative simplicity of the technology and expected low cost of monolithic silicon IR SB FPAs with basic parameters compared with hybrid IR FPAs for the wavelength ranges from 3 ?m to 5 ?m and from 8 ?m to 12 ?m maintain large monolithic IR SB FPAs as a basis for developments of double application digital TICs in the Russian Federation.

Arutunov, V. A.; Vasilyev, I. S.; Ivanov, V. G.; Prokofyev, A. E.

2003-09-01

366

Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 185 citations and includes a subject term index and title list.)

NONE

1994-02-01

367

Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search  

SciTech Connect

The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 204 citations and includes a subject term index and title list.)

Not Available

1994-12-01

368

Laser cooling and trapping of atomic particles. (Latest citations from the NTIS data base). Published Search  

SciTech Connect

The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications for high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion are examined. (Contains a minimum of 151 citations and includes a subject term index and title list.)

Not Available

1992-04-01

369

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

370

Electron impact induced fluorescence of dissociating fragments from jet-cooled methane, methanol and ethanol  

NASA Astrophysics Data System (ADS)

Dissociation fragments, following 20 keV electron impact on supersonic jet targets of methane, methanol and ethanol, have been analysed to determine rotational temperatures. The intensities of individual rotational lines of the CH A2 ?-X2?, CH B2?- -X2? and CH+A1 ?-X1?+ transitions were measured and fitted to Boltzmann distributions. The temperatures obtained were about 4000 K for the CH A-X, 2000 K for the B-X and 1650 K for the CH+A-X transitions. The recorded spectra showed distributions at single temperatures. The intensities were also fitted to theoretical distributions in order to obtain excess energies. Possible fragmentation mechanisms are discussed.

Kindvall, G.; Larsson, M.; Olsson, B. J.; Sigray, P.

1986-12-01

371

An experimental and ab initio study of the electronic spectrum of the jet-cooled F2BO free radical.  

PubMed

We have studied the [Formula: see text] (2)A1-[Formula: see text] (2)B2 laser-induced fluorescence (LIF) spectrum of the jet-cooled F2BO radical for the first time. The transition consists of a strong [Formula: see text] band at 446.5 nm and eight weak sequence bands to shorter wavelengths. Single vibronic level emission spectra obtained by laser excitation of individual levels of the [Formula: see text] state exhibit two electronic transitions: a very weak, sparse [Formula: see text]-[Formula: see text] band system in the 450-500 nm region and a stronger, more extensive set of [Formula: see text] (2)A1-[Formula: see text] (2)B1 bands in the 580-650 nm region. We have also performed a series of high level ab initio calculations to predict the electronic energies, molecular structures, vibrational frequencies, and rotational and spin-rotation constants in the [Formula: see text] (2)B2, [Formula: see text](2)B1 and [Formula: see text] (2)A1 electronic states as an aid to the analysis of the experimental data. The theoretical results have been used as input for simulations of the rotationally resolved [Formula: see text] (2)A1-[Formula: see text] (2)B2 [Formula: see text] LIF band and Franck-Condon profiles of the LIF and single vibronic level emission spectra. The agreement between the simulations obtained with purely ab initio parameters and the experimental spectra validates the geometries calculated for the ground and excited states and the conclusion that the radical has C2v symmetry in the [Formula: see text], [Formula: see text], and [Formula: see text] states. The spectra provide considerable new information about the vibrational energy levels of the [Formula: see text] and [Formula: see text] states, but very little for the [Formula: see text] state, due to the very restrictive Franck-Condon factors in the LIF spectra. PMID:24784265

Grimminger, Robert; Sheridan, Phillip M; Clouthier, Dennis J

2014-04-28

372

An experimental and ab initio study of the electronic spectrum of the jet-cooled F2BO free radical  

NASA Astrophysics Data System (ADS)

We have studied the tilde B 2A1-tilde X 2B2 laser-induced fluorescence (LIF) spectrum of the jet-cooled F2BO radical for the first time. The transition consists of a strong 0_0^0 band at 446.5 nm and eight weak sequence bands to shorter wavelengths. Single vibronic level emission spectra obtained by laser excitation of individual levels of the tilde B state exhibit two electronic transitions: a very weak, sparse tilde B-tilde X band system in the 450-500 nm region and a stronger, more extensive set of tilde B 2A1-tilde A 2B1 bands in the 580-650 nm region. We have also performed a series of high level ab initio calculations to predict the electronic energies, molecular structures, vibrational frequencies, and rotational and spin-rotation constants in the tilde X 2B2, tilde A2B1 and tilde B 2A1 electronic states as an aid to the analysis of the experimental data. The theoretical results have been used as input for simulations of the rotationally resolved tilde B 2A1-tilde X 2B2 0_0^0 LIF band and Franck-Condon profiles of the LIF and single vibronic level emission spectra. The agreement between the simulations obtained with purely ab initio parameters and the experimental spectra validates the geometries calculated for the ground and excited states and the conclusion that the radical has C2v symmetry in the tilde X, tilde A, and tilde B states. The spectra provide considerable new information about the vibrational energy levels of the tilde X and tilde A states, but very little for the tilde B state, due to the very restrictive Franck-Condon factors in the LIF spectra.

Grimminger, Robert; Sheridan, Phillip M.; Clouthier, Dennis J.

2014-04-01

373

BRIEF COMMUNICATIONS: Energy and spectral characteristics of a cw electron-beam-controlled CO2 laser with cryogenic cooling of the working mixture  

Microsoft Academic Search

An experimental investigation was made of the improvement in the energy characteristics of a cw electron-beam-controlled CO2 laser as a result of cooling of its working mixture to Tapprox200 K. A physical efficiency of 24% was achieved. The spectral composition of the radiation emitted by this CO2 laser was determined for different initial gas temperatures.

A. P. Averin; N. G. Basov; E. P. Glotov; V. A. Danilychev; G. N. Karpov; O. M. Kerimov; V. M. Krasovskii; M. M. Malysh; N. N. Sazhina; A. M. Soroka; V. E. Tsepelev; N. D. Ustinov; N. V. Cheburkin

1985-01-01

374

Cooling of Stored Beams  

SciTech Connect

Beam cooling methods developed for the accumulation of antiprotons are being employed to assist in the performance of experiments in Nuclear and Particle Physics with ion beams stored in storage rings. The physics of beam cooling, and the ranges of utility of stochastic and electron cooling are discussed in this paper.

Mills, F.

1986-06-10

375

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

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

376

Electromagnetic Suspension.  

National Technical Information Service (NTIS)

The electromagnetic suspension suggested differs from known suspensions in that its rotor is made in the form of a rod placed between the poles of the electromagnets of an n-phase system. This invention can be used in gravimetry and gyroscopic devices. (A...

B. V. Bolotov L. Z. Piven

1973-01-01

377

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

378

Virtual Electromagnet  

NSDL National Science Digital Library

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

Regents, The U.

2014-01-01

379

Cooling Rates in Splat Cooling.  

National Technical Information Service (NTIS)

Calculations and experimental observations made on cooling rates during splat quenching are presented. Three possible types of cooling behavior are discussed: ideal cooling, intermediate cooling, and Newtonian cooling. The effects of splatting-process var...

R. C. Ruhl

1966-01-01

380

Noise Temperature and IF Bandwidth of a 530 GHz Heterodyne Receiver Employing a Diffusion-Cooled Superconducting Hot-Electron Mixer  

NASA Technical Reports Server (NTRS)

We report on the first heterodyne measurements with a diffusion-cooled hot-electron bolometer mixer in the submillimeter wave band, using a waveguide mixer cooled to 2.2 K. The best receiver noise temperature at a local oscillator frequency of 533 GHz and an intermediate frequency of 1.4 GHz was 650 K (double sideband). The 3 dB IF roll-off frequency was around 1.7 to 1.9 GHz, with a weak dependence on the device bias conditions.

Skalare, A.; McGrath, W. R.; Bumble, B.; LeDuc, H. G.; Burke, P. J.; Verheijen, A. A.; Prober, D. E.

1995-01-01

381

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

382

Nuclear Electromagnetic Pulse Review  

Microsoft Academic Search

Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and

Michael Dinallo

2011-01-01

383

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

NASA Astrophysics Data System (ADS)

The dissociation pathways of HeH+ 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+(1s)+H(nl) and He(1snl)+H+ were separated and the He(1snl)+H+ channel was particularly studied by coincidence detection of the He and H+ fragments on two separate fragment detectors. At 32 nm excitation, the branching ratio between the product channels was found to be ?He++H/?He+H+=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?3-4) of the emerging atomic fragments irrespective of the initial vibrational excitation of HeH+. The fragment angular distributions showed that dissociation into the He+H+ channel mostly (~70%) proceeds through 1? states, while for the He++H channel 1? and 1? states are of about equal importance.

Pedersen, H. B.; Lammich, L.; Domesle, C.; Jordon-Thaden, B.; Heber, O.; Ullrich, J.; Treusch, R.; Guerassimova, N.; Wolf, A.

2010-08-01

384

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

385

Nuclear Electromagnetic Pulse Review  

NASA Astrophysics Data System (ADS)

Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets -- fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

Dinallo, Michael

2011-04-01

386

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

SciTech Connect

Nasr and Hasanbeigi in their comment [Phys. Plasmas 17, 093103 (2010)] have claimed that, in our recent paper [Phys. Plasmas 17, 093103 (2010)], incorrect initial conditions have been used based on dispersion relation (or normalized electromagnetic wave frequency {omega}{sub w}) and mean axial velocity {beta}{sub b}. We use a self-consistent method to calculate more accurate values of {omega}{sub w} and {beta}{sub b} and show that all results presented in our recent paper are correct.

Esmaeilzadeh, Mahdi; Taghavi, Amin [Department of Physics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of)

2011-05-15

387

Electromagnetic properties of open and closed overmoded slow-wave resonators for interaction with relativistic electron beams  

SciTech Connect

Specific slow wave structures are needed in order to produce coherent Cherenkov radiation in overmoded relativistic generators. The electromagnetic characteristics of such slow wave, resonant, finite length structures commonly used in relativistic backward wave oscillators have been studied both experimentally and theoretically. In experiments, perturbation techniques were used to study both the fundamental and higher order symmetric transverse magnetic (TM) modes. Finite length effects lead to end reflections and quantization of the wave number. The effects of end reflections in open slow wave structures were found from the spectral broadening of the discrete resonances of the different axial modes. The measured axial and radial field distributions are in excellent agreement with the results of a 2-D code developed for the calculation of the fields in these structures.

Main, W. (ACCURAY, Inc., Santa Clara, CA (United States)); Carmel, Y.; Weaver, J. (Univ. of Maryland, College Park, MD (United States). Inst. for Plasma Research) (and others)

1994-10-01

388

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

389

Survey Of Cooling Techniques  

NASA Technical Reports Server (NTRS)

Methods of maintaining electronics at best operating temperatures reviewed. Paper surveys cooling techniques for electronic components and sensors that must be kept at temperatures ranging from thousandths of kelvin to room temperature. Discusses characteristics of various coolers in terms of ground and space applications, cooling capacity, reliability, and temperature range. Also discusses briefly, cooling of conventional electronic circuitry operating few degrees above environmental temperature by natural or forced convection of air or liquid. At greater length, discusses passive and active refrigeration of "cold" electronic circuitry operating below environmental temperature.

Chan, Chung K.

1989-01-01

390

Electromagnetic particle simulation codes  

NASA Technical Reports Server (NTRS)

Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

Pritchett, P. L.

1985-01-01

391

Aircraft electromagnetic compatibility  

NASA Technical Reports Server (NTRS)

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

Clarke, Clifton A.; Larsen, William E.

1987-01-01

392

Electromagnetic Hypersensitivity  

Microsoft Academic Search

\\u000a Electromagnetic hypersensitive persons (EHS) attribute their nonspecific health symptoms to environmental electromagnetic\\u000a fields (EMF) of different sources in or outside their homes. In general, causal attribution is not restricted to specific\\u000a EMF frequencies but involves a wide range from extremely low frequencies (ELF) up to radio frequencies (RF) including mobile\\u000a telecommunication microwaves and radar. EHS argue that existing exposure limits

Norbert Leitgeb

393

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.

394

Noise Temperature and Absorbed LO Power Measurement Methods for NbN Phonon-Cooled Hot Electron Bolometric Mixers at Terahertz Frequencies  

Microsoft Academic Search

In this paper the absorbed LO power requirements and the noise performance of NbN based phonon-cooled hot electron bolometric (HEB) quasioptical mixers are investigated for RF frequencies in the 0.55-1.1 range The minimal measured DSB noise temperatures are about 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz and 1250 K at 1.1 THz.

Harald F. Merkel; Pavel A. Yagoubov; Matthias Kroug; Pourya Khosropanah; Erik L. Kollberg; Gregory N. Gol'tsman; Eugene M. Gershenzon

1998-01-01

395

Emergent electromagnetism in solids  

NASA Astrophysics Data System (ADS)

The electromagnetic field (EMF) is the most fundamental field in condensed-matter physics. Interaction between electrons, electron-ion interaction and ion-ion interaction are all of electromagnetic origin, while the other three fundamental forces, i.e. the gravitational force and weak and strong interactions, are irrelevant in the energy/length scales of condensed-matter physics. Also the physical properties of condensed matter, such as transport, optical, magnetic and dielectric properties, are almost described as their electromagnetic responses. In addition to this EMF, it often happens that the gauge fields appear as the emergent phenomenon in the low-energy sector due to the projection of the electronic wavefunctions onto the curved manifold of the Hilbert sub-space. These emergent EMFs play important roles in many places in condensed-matter physics including the quantum Hall effect, strongly correlated electrons and also in non-interacting electron systems. In this paper, we describe the fundamental idea behind it and some of its applications studied recently.

Nagaosa, Naoto; Tokura, Yoshinori

2012-01-01

396

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

397

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

398

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

Microsoft Academic Search

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

William M Fawley; Jean-Luc Vay

2009-01-01

399

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

400

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

401

Electromagnetic shocks on the optical cycle of ultrashort pulses in triple-resonance Lorentz dielectric media with subfemtosecond nonlinear electronic Debye relaxation.  

PubMed

The dynamical evolution of an intense ultrashort sub-10-fs two-cycle optical pulse is considered as it propagates through a transparent third-order dielectric medium characterized by three resonance lines and a finite sub-fs relaxation time of the electronic nonlinearity. Numerical integration of the full Maxwell's equations incorporating triple-resonance Lorentz linear dispersion and Debye nonlinear dispersion, for a linearly polarized electromagnetic pulse centered at lambda(0)=1.24 microm in the normal dispersion region near the zero dispersion wavelength, shows the formation of shocks occurring on the optical cycle due to the generation of optical harmonics. The finite relaxation time of the nonlinear electronic response (sub-fs time scale) (i) slows down the steepening rate of the optical cycle; (ii) does not limit the generation of strongly phase matched optical harmonics, and consequently the development of infinitely sharp edges on the optical cycle producing its breaking when linear dispersion is not included; (iii) reduces the production of phase matched harmonics and consequently the sharpening of the jumps when dispersion is present, compared to the case of an instantaneous nonlinear response; and (iv) reduces the harmonic spectrum spreading and modulation at later times on the appearance of self-steepening of the electric field envelope. PMID:11969852

Gilles, L; Moloney, J V; Vázquez, L

1999-07-01

402

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

Microsoft Academic Search

We propose a new particle acceleration mechanism. Electron can be accelerated to relativistic energy within a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic field resonance acceleration (EMRA). We find that the electron acceleration depends not only on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave frequency.

Hong Liu; X. T. He; S. G. Chen; W. Y. Zhang

2004-01-01

403

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

404

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

405

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

406

Cooling of a multichip electronic module by means of confined two-dimensional jets of dielectric liquid  

SciTech Connect

Experiments were performed to investigate single-phase heat transfer froma smooth 12.7 {times} 12.7 mm{sup 2} simulated chip to a two-dimensional jet of dielectric Fluorinert FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confined channel height, and impingement velocity have been examined. Channel height had a negligible effect ont eh theat transfer performance of the jet for the conditions of the present study. A correlation for the convective heat transfer coefficient is presented as a function of jet, width, heat length, flow velocity, and fluid properties. A self-contained multichip cooling module consisting of a 3 {times} 3 array of heat sources confirmed the uniformity and predictability of cooling for each of the nine chips, and proved the cooling module is well suited for packaging large arrays of high-power density chips.

Wadsworth, D.C.; Mudawar, I. (Purdue Univ., West Layfayette, IN (USA))

1990-11-01

407

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

408

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

409

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

410

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

411

Noise Temperature and IF Bandwidth of a 530GHz Diffusion-Cooled Hot-Electron Bolometer Mixer.  

National Technical Information Service (NTIS)

Superconducting hot-electron bolometers are currently of significant interest for use in heterodyne receivers at frequencies above 1 THz for radio astronomy applications. The mixing process in this type of device relies on heating of the electron gas, whi...

A. Skalare W. R. McGrath B. Bumble H. G. LeDuc P. J. Burke A. A. Verheijen D. E. Prober

1995-01-01

412

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

SciTech Connect

A fourfold increase in the conversion of thermal electron Bernstein waves ~EBW! to the extraordinary mode (X mode! was measured when the density scale length (Ln) was progressively shortened by a local boron nitride limiter in the scrape-off of an Ohmically heated National Spherical Torus Experiment plasma @M. Ono, S. Kaye, M. Peng et al., Proceedings of the 17th IAEA Fusion Energy Conference ~IAEA, Vienna, 1999!, Vol. 3, p. 1135#. The maximum conversion efficiency approached 50% when Ln was reduced to 0.7 cm, in agreement with theoretical predictions that used locally measured Ln . Calculations indicate that it is possible to establish Ln ,0.3 cm with a local limiter, a value predicted to attain ;100% EBW conversion to the X mode in support of proposed EBW heating and current drive scenarios. 2003 American Institute of Physics. @DOI: 10.1063/1.1564081#

Taylor, G. [Princeton Plasma Physics Laboratory (PPPL); Efthimion, P. C. [Princeton Plasma Physics Laboratory (PPPL); Jones, B. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B [Princeton Plasma Physics Laboratory (PPPL); Wilson, J. R. [Princeton Plasma Physics Laboratory (PPPL); Wilgen, John B [ORNL; Bell, Gary L [ORNL; Bigelow, Tim S [ORNL; Maingi, Rajesh [ORNL; Rasmussen, David A [ORNL; Harvey, R. W. [CompX, Del Mar, CA; Smirnov, A. [Moscow State University; Paoletti, F. [Columbia University; Sabbagh, S. A. [Columbia University

2003-01-01

413

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

414

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

415

Channel shape optimization of electromagnetic pumps  

SciTech Connect

Electromagnetic pumps are used for the transportation of liquid metals such as the cooling sodium of fast breeder nuclear reactors. The design of this induction machine is close to that of a tubular linear induction motor. In this paper, channels of variable cross section are used to improve the efficiency of electromagnetic pumps. The optimum channel shape is derived analytically and is then tested with a finite element code. The performances are compared with those of standard pumps.

Leboucher, L.; Boissonneau, P. [LEGI, Genoble (France). Inst. de Mecanique de Grenoble] [LEGI, Genoble (France). Inst. de Mecanique de Grenoble; Villani, D. [Framatome direction Novatome, Lyon (France)] [Framatome direction Novatome, Lyon (France)

1995-05-01

416

Slot design of optimized electromagnetic pump  

SciTech Connect

Electromagnetic pumps are used for the transportation of liquid metals such as the cooling sodium of fast breeder nuclear reactors. The design of this induction machine is close to that of a tubular linear induction motor. A non uniform slot distribution is used to optimize electromagnetic pumps. This geometry is tested with a finite element code. The performances are compared with the regular slot distribution of Industrial prototypes.

Leboucher, L. (LEGI, Grenoble (France). Institut de Mecanique); Villani, D. (Framatome direction Novatome, Lyon (France))

1993-11-01

417

Laser cooling and trapping of atomic particles. January 1970-September 1989 (Citations from the NTIS data base). Report for Jan 70-Sep 89  

SciTech Connect

This bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps with very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications include high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains 97 citations fully indexed and including a title list.)

Not Available

1989-11-01

418

Stochastic Cooling  

SciTech Connect

Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

Blaskiewicz, M.

2011-01-01

419

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

420

A hot-spot mixer model for phonon-cooled NbN hot electron bolometric mixers  

Microsoft Academic Search

Based on a one dimensional heat transport equation for the electrons in a super-conducting hot electron bolometer (HEB) a model for a hot spot mixer is see up. The hot spot parameters are applied in a small signal oscillator model predicting IV curves and conversion gain. Besides its normal resistance and its IF bandwidth a HEB around its optimal operating

Harald Merkel; Pourya Khosropanah; P. Yagoubov; E. Kollberg

1999-01-01

421

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Special features of the transmission of a train of electromagnetic waves across transparent plates  

NASA Astrophysics Data System (ADS)

An investigation is reported of the special features of the temporal and spectral characteristics of radiation reflected from and transmitted by a plane-parallel plate when this radiation is in the form of a train of plane electromagnetic waves which is limited in space. Attention is drawn to the possibility of conversion of trains of electromagnetic waves into a sequence of shorter trains separated by distances equal to their length. Possible applications of such trains are considered.

Bessonov, Evgenii G.; Vnukova, M. L.

1995-12-01

422

Electromagnetic Simulation Studies of Photocathode Sources  

Microsoft Academic Search

We present the results of electromagnetic simulation studies on space-charge dominated electron beams produced by photocathode sources. In particular, we demonstrate the computational requirements on the Green's function based simulation code IRPSS (Indiana Rf Photocathode Source Simulator) for obtaining relative space-charge electromagnetic field errors of at most 1%, and show how these fields compare with electrostatic based field solver methods.

Mark Hess; Chong Shik Park

2007-01-01

423

Superconducting electromagnetic thruster  

NASA Astrophysics Data System (ADS)

An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

Meng, James C.

1994-08-01

424

Superconducting electromagnetic thruster  

SciTech Connect

An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

Meng, J.

1993-02-11

425

Experimental investigation for enhancement of heat transfer from cooling of electronic components by circular air jet impingement  

NASA Astrophysics Data System (ADS)

An experimental investigation is carried out to study the enhancement of heat transfer from surface of the electronic components by impingement of a circular air jet. Local and stagnation Nusselt number on the impinged surface of the electronic components are presented for different nozzle configurations. Reynolds number, based on nozzle diameter ( d) is varied between 5,500 and 28,500 and nozzle-to-electronic component spacing from 2 to 10 nozzle diameters. The measured data were correlated into a simple equation and compared to the predictions of several other correlations proposed by other researchers. The heat transfer mechanisms involved in the enhanced performance are discussed. The study provides a lot of useful information for the application of impinging jet heat transfer in electronic industry.

Anwarullah, M.; Vasudeva Rao, V.; Sharma, K. V.

2012-09-01

426

Creating an Electromagnet  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

427

Electromagnetic microactuators  

NASA Astrophysics Data System (ADS)

High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

2013-05-01

428

Sorption cooling: a valid extension to passive cooling  

NASA Astrophysics Data System (ADS)

Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into limitations that prohibit accommodation on a spacecraft. The approach to this issue has been to find a technology able to supplement passive cooling for lower temperatures, which maintains as much as possible of the advantages of passive coolers. Sorption cooling employs a closed cycle Joule-Thomson expansion process to achieve the cooling effect. Sorption cells perform the compression phase in this cycle. At a low temperature and pressure, these cells adsorb the working fluid. At a higher temperature they desorb the fluid and thus produce a high-pressure flow to the restriction in the cold stage. The sorption process selected for this application is of the physical type, which is completely reversible. It does not suffer from degradation as is the case with chemical sorption of e.g. hydrogen in metal hydrides. Sorption coolers include no moving parts except for some check valves, they export neither mechanical vibrations nor electromagnetic interference, and are potentially very dependable due to their simplicity. The required cooling temperature determines the type of working fluid to be applied. Sorption coolers can be used in conjunction with passive cooling for heat rejection at different levels. This paper starts with a brief discussion on applications of passive coolers in different types of orbits and the limitations on passive cooling at low cooling temperatures. Next, the working principle of sorption cooling is summarized. The DARWIN mission is chosen as an example application of sorption and passive cooling and special attention is paid to the reduction of the radiator area needed by the sorption cooler. By examining the performance of alternative working fluids suitable for different cooling temperatures, the application field of this type of sorption cooling is currently expanded.

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

2007-10-01

429

Sorption cooling: A valid extension to passive cooling  

NASA Astrophysics Data System (ADS)

Passive cooling has shown to be a very dependable cryogenic cooling method for space missions. Several missions employ passive radiators to cool down their delicate sensor systems for many years, without consuming power, without exporting vibrations or producing electromagnetic interference. So for a number of applications, passive cooling is a good choice. At lower temperatures, the passive coolers run into limitations that prohibit accommodation on a spacecraft. The approach to this issue has been to find a technology able to supplement passive cooling for lower temperatures, which maintains as much as possible of the advantages of passive coolers. Sorption cooling employs a closed cycle Joule-Thomson expansion process to achieve the cooling effect. Sorption cells perform the compression phase in this cycle. At a low temperature and pressure, these cells adsorb the working fluid. At a higher temperature they desorb the fluid and thus produce a high-pressure flow to the expander in the cold stage. The sorption process selected for this application is of the physical type, which is completely reversible. It does not suffer from degradation as is the case with chemical sorption of, e.g., hydrogen in metal hydrides. Sorption coolers include no moving parts except for some check valves, they export neither mechanical vibrations nor electromagnetic interference, and are potentially very dependable due to their simplicity. The required cooling temperature determines the type of working fluid to be applied. Sorption coolers can be used in conjunction with passive cooling for heat rejection at different levels. This paper starts with a brief discussion on applications of passive coolers in different types of orbits and on the limitations of passive cooling for lower cooling temperatures. Next, the working principle of sorption cooling is summarized. The DARWIN mission is chosen as an example application of sorption and passive cooling and special attention is paid to the reduction of the radiator area needed by the sorption cooler. The application field of this type of sorption cooling in space missions is currently being expanded by examining the performance of alternative working fluids, suitable for different cooling temperatures.

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

2008-05-01

430

Electromagnetic strong plasma turbulence  

NASA Astrophysics Data System (ADS)

The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c<=v<=0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v>=0.1c to just free eigenstates for v<=0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

Melatos, A.; Jenet, F. A.; Robinson, P. A.

2007-02-01

431

Transient electromagnetic interference in substations  

Microsoft Academic Search

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

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

1994-01-01

432

Millimeter wave electromagnetic measurement techniques  

Microsoft Academic Search

This report presents the results of studies to develop the rationale for electromagnetic measurement techniques for use in the EMC evaluation of millimeter wave (MMW) communication-electronic equipment and systems. In the development of this rationale, seven basic tasks were performed. Under the first task, the EMC\\/EMI data requirements for MMW equipments and systems were established to provide a clear definition

E. E. Donaldson; J. C. Mantovani; G. B. Melson; D. W. Acree

1982-01-01

433

Antiproton cooling in the Fermilab Recycler Ring  

SciTech Connect

The 8.9-GeV/c Recycler antiproton storage ring is equipped with both stochastic and electron cooling systems. These cooling systems are designed to assist accumulation of antiprotons for the Tevatron collider operations. In this paper we report on an experimental demonstration of electron cooling of high-energy antiprotons. At the time of writing this report, the Recycler electron cooling system is routinely used in collider operations. It has helped to set recent peak luminosity records.

Nagaitsev, S.; Bolshakov, A.; Broemmelsiek, D.; Burov, Alexey V.; Carlson, K.; Gattuso, C.; Hu, M.; Kazakevich, G.; Kramper, B.; Kroc, T.; Leibfritz, J.; Prost, L.; Pruss, S.; Saewert, G; Schmidt, C.W.; Seletskiy, S.; Shemyakin, A.; Sutherland, M.; Tupikov, V.; Warner, A.; Zenkevich, P.; /Fermilab /Moscow, ITEP /Novosibirsk, IYF /Rochester U.

2005-12-01

434

Relativistic Particle Motion in Nonuniform Electromagnetic Waves.  

National Technical Information Service (NTIS)

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 vario...

G. Schmidt T. Wilcox

1973-01-01

435

Injection Molding Compound for Electromagnetic Shielding.  

National Technical Information Service (NTIS)

A thermoplastic injection molding compound with excellent electromagnetic shielding effectiveness has been developed as a material for housings of electronic equipment. The compound contains stainless steel fiber as an electroconductive filler and maintai...

H. Takahama H. Tamaki T. Herai

1988-01-01

436

Superconductive Levitated Armatures for Electromagnetic Launchers.  

National Technical Information Service (NTIS)

An electromagnetic railgun launcher and armature. The armature is made from superconducting material and is levitated between the rails of the launcher by the Meissner effect. The Meissner effect is created by cooling the armature and subjecting it to a m...

L. J. Jasper

1988-01-01

437

Electromagnetic valve  

US Patent & Trademark Office Database

In an electromagnetic valve, a composite valve case has a cylindrical hollow and a composite valve body formed in spool shape is slidably housed in the cylindrical hollow. The composite valve body has not only an inherent valve function for changing fluid path area according to its movement in the cylindrical hollow but also an armature function for constituting a magnetic circuit. The composite valve case has not only a cylinder function for allowing the valve body to slidably move but also a stator function for constituting a magnetic circuit. The composite valve body and the composite valve case are made of soft magnetic material and are provided at their surfaces with thin hardened layers formed by surface or heat treatment.

2003-12-30

438

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

439

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

440

Cooled Low-Noise HEMT Microwave Amplifiers  

NASA Technical Reports Server (NTRS)

Prototype cooled low-noise microwave amplifiers based on high-electron-mobility transistors (HEMT's) considered as replacements for cooled ruby masers used as low-noise receiver-front-end amplifiers in communications, radio science, radar systems, radio astronomy, and telemetry. HEMT amplifier operates at 12 K, requires less cooling power and operates at lower cost with simpler, more-reliable cooling system.

Bautista, J. Javier; Ortiz, Gerardo G.; Duh, Kuanghann George

1992-01-01

441

Electronic spectroscopy of jet-cooled HCP+: Molecular structure, phosphorus hyperfine structure, and Renner-Teller analysis  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence spectra of jet-cooled HCP+ and DCP+ have been obtained with the pulsed discharge technique using HCP/DCP and argon precursor mixtures. Transitions involving all of the excited state vibrations have been observed and a set of vibrational constants has been obtained. High-resolution spectra of the 2?3/2 components of the 000 bands of both isotopomers have been recorded, and these spectra show resolved phosphorus hyperfine structure which allowed the determination of the excited state Fermi contact parameter. The B values were used to obtain the ground and excited state effective geometric parameters as r0''(CH)=1.077(2) A?, r0''(CP)=1.6013(3) A?, r0'(CH)=1.082(2) A?, and r0'(CP)=1.5331(3) A?. A Renner-Teller analysis of the ground state vibrational energy levels obtained from the literature was attempted. All of the observed levels of DCP+ and the majority of those of HCP+ were satisfactorily fitted with a standard Renner-Teller model, but three HCP+ levels showed large systematic deviations which could not be accommodated by reassignments or improvements in the Fermi resonance Hamiltonian. Further improvements in the theory or in the experimental data will be needed to resolve this discrepancy.

Sunahori, Fumie X.; Zhang, Xiaopeng; Clouthier, Dennis J.

2007-09-01

442

a Spectroscopic Study of the Linear-Bent Electronic Transitions of Jet-Cooled BCl_2 and HBCl  

NASA Astrophysics Data System (ADS)

Laser induced fluorescence (LIF) and single vibronic level emission spectra (SVL) of jet-cooled BCl_2 and HBCl have been measured. The radicals were produced in a pulsed electric discharge of a mixture of BCl_3/Ar and BCl_3/H_2/Ar, respectively. The LIF spectra of both radicals are congested due to overlapping bands from the boron and chlorine isotopes. In addition, the ground and first excited states are the two Renner-Teller components of a ^2? state split by a strong vibronic interaction. The Franck-Condon profile of the tilde{A}^2B_1 - tilde{X}^2A_1 band system of BCl_2 and the tilde{A}^2A'' - tilde{X}^2A' system of HBCl are characteristic of linear-bent excitations. Excited state bending progressions have been identified in both species using the LIF-sync scan procedure in which the monochromator is offset by a value corresponding to a ground state fundamental frequency of the target molecule and scanned simultaneously with the dye laser. LIF spectra of individual isotopes can thus be recorded. Ground state vibrational frequencies have been deduced from SVL spectra. The emission spectra for BCl_2, are dominated by progressions in the symmetric stretching (?_1) and bending (?_2) modes. In the case of HBCl, progressions in the bending (?_2) and BCl stretching (?_3) modes were observed.

Nagarajan, Ramya; Yang, Jie; Clouthier, Dennis J.

2011-06-01

443

Research on the detuning system of a cooling electron beam for the dielectronic recombination experiment at CSRm  

NASA Astrophysics Data System (ADS)

A storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination (DR) experiments. In order to fulfill the requirement of DR measurements at the main Cooler Storage Ring, a detuning system for the precision control of the relative energy between the ion beam and the electron beam has been installed on the electron cooler device. The test run using 7.0 MeV/u C6+ beam was performed with recording the Schottky spectra and the ion beam currents. The influence of pulse heights and widths of the detuning voltage on the ion beam was analyzed. For the small pulse height, the experimental results from the Schottky spectra were in good agreement with the theoretical results. The frequency shift in the Schottky spectra was significantly reduced for the short pulse width. For the large pulse height, an oscillation phenomenon was observed and some effective ways to reduce the oscillation were pointed out. The detailed description of the phenomenon and the theoretical model based on the plasma oscillation is discussed in this paper. The overall results show that the new detuning system works properly, and could fulfill the requirements of future DR experiments.

Meng, Ling-Jie; Ma, Xin-Wen; V. Parkhomchuk, V.; Yang, Xiao-Dong; B. Reva, V.; Li, Jie; Mao, Li-Jun; Ma, Xiao-Ming; Yan, Tai-Lai; Xia, Jia-Wen; Yuan, You-Jin; Xu, Hu-Shan; Yang, Jian-Cheng; Xiao, Guo-Qing

2013-01-01

444

Radiation effect and relaxation layer in electro-magnetically driven strong shock waves  

NASA Astrophysics Data System (ADS)

Strong shock waves play a crucial role in many astrophysical phenomena. Ion-electron relaxation process and radiation affect the structure of strong shock waves. Since the non-linear nature of the relaxation process makes the plasma behavior extremely complicated, it requires well-defined shock wave formation to estimate the structure. We investigate electro-magnetically driven shock in laboratory experiments. The pulse power device with tapered electrodes can generate a quasi steady and 1-D shock [1], which allows for analysis of ion-electron relaxation and radiation processes. We will show results of electron temperature measurement by a line pair method and radiative cooling, which restricts the increase of electron temperature. [4pt] [1] K. Kondo, M. Nakajima, T. Kawamura and K. Horioka, Rev. Sci. Instr. 77, 036104 (2006).

Kondo, Kotaro; Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko

2009-11-01

445

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

446

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

447

Electromagnetic interference reduction using electromagnetic bandgap structures in packages, enclosures, cavities, and antennas  

Microsoft Academic Search

Electromagnetic interference (EMI) is a source of noise problems in electronic devices. The EMI is attributed to coupling between sources of radiation and components placed in the same media such as package or chassis. This coupling can be either through conducting currents or through radiation. The radiation of electromagnetic (EM) fields is supported by surface currents. Thus, minimizing these surface

Baharak Mohajer Iravani

2007-01-01

448

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

449

Coherent Superwide in Frequency Space Electromagnetic Pulse as a Soliton Propagating with Light Velocity  

Microsoft Academic Search

An electromagnetic soliton that cannot be described in terms of the envelope approximation can be excited by electromagnetic pulse or by electron bunch. This soliton is very important in the problems of the wake-field excitation, particle acceleration and formation of coherent superwide in frequency space electromagnetic pulse. Many investigations is devoted to the problem of existence of electromagnetic solitary perturbations.

Vladimir M. Khoruzhy; Vasili I. Maslov

1997-01-01

450

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

451

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

452

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

Microsoft Academic Search

We propose a new particle acceleration mechanism. Electron can be accelerated\\u000ato relativistic energy within a few electromagnetic wave cycles through the\\u000amechanism which is named electromagnetic and magnetic field resonance\\u000aacceleration (EMRA). We find that the electron acceleration depends not only on\\u000athe electromagnetic wave intensity, but also on the ratio between electron\\u000aLarmor frequency and electromagnetic wave frequency.

Hong Liu; X. T. He; S. G. Chen; W. Y. Zhang

2004-01-01

453

Cool Suit  

NASA Technical Reports Server (NTRS)

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

1987-01-01

454

Analysis of distributed cooled high power millimeter wave windows  

SciTech Connect

The sectional high-frequency (100--170 GHz) distributed cooled window has been investigated both electromagnetically and thermally previously using computational electromagnetics (EM) and thermal codes. Recent data describes the relationship to some experimental data for the window. Results are presented for time domain CW EM analyses and CW thermal and stress calculations.

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

1995-09-09

455

Nanostructured transparent thin films for frequency-selective electromagnetic shielding  

Microsoft Academic Search

SUMMARY Transparent electromagnetic shields are used in several industrial sectors. Examples are the displays of video terminals, of electrical and electronic equipment, of electromedical instruments, of portable electronic devices. They can also be exploited in automotive and aerospace applications to prevent the penetration into the craft, through the direct coupling with the windows, of high intensity electromagnetic fields (HIRF) emitted

M. D'Amore; M. S. Sarto; F. Sarto; A. Tamburrano

456

On the Electromagnetic Pulse Produced by Nuclear Explosions  

Microsoft Academic Search

The electromagnetic pulse (EMP) produced by the gamma rays from nuclear explosions is discussed. The gamma rays produce a current of Compton recoil electrons, and these electrons produce further ionization so that the air becomes conducting. The Compton current leads to the generation of electromagnetic fields according to Maxwell's equations. The conductivity tends to limit the magnitude of the fields.

Conrad Longmire

1978-01-01

457

On the electromagnetic pulse produced by nuclear explosions  

Microsoft Academic Search

The electromagnetic pulse (EMP) produced by the gamma rays from nuclear explosions is discussed. The gamma rays produce a current of Compton recoil electrons, and these electrons produce further ionization so that the air becomes conducting. The Compton current leads to the generation of electromagnetic fields according to Maxwell's equations. The conductivity tends to limit the magnitude of the fields.

CONRAD L. LONGMIRE

1978-01-01

458

The S1(1A1)-S0(1A1) Electronic Transition of Jet-Cooled o-Difluorobenzene.  

PubMed

A detailed study of the S1(1A1)-S0(1A1) transition of jet-cooled o-difluorobenzene has been completed using the two techniques of laser-induced fluorescence excitation and dispersed, single vibronic level fluorescence spectroscopy. Analysis of over 60 dispersed fluorescence spectra resulted in both the assignment of 22 excited state vibrational frequencies and the confirmation of 23 ground state frequencies. The spectrum is dominated by Franck-Condon activity in totally symmetric vibrations with long progressions in the ring-breathing mode, nu9. By analogy with benzene and the para- and meta-substituted isomers, two vibronic coupling mechanisms are postulated to be responsible for the wealth of weaker symmetry-forbidden structure that has been observed. Single quantum changes in b2 vibrations are postulated to appear due to first order vibronic coupling to a higher lying B2 electronic state. Combinations of b1 and a2 modes are postulated to appear from second order vibronic coupling to an A1 electronic state. This second order coupling causes a pronounced Duschinsky mixing among excited state b1 and a2 modes with respect to their ground state counterparts. Franck-Condon factors are calculated for the a1 progression-forming modes, anharmonic contributions are evaluated, one strong Fermi resonance is identified and analyzed, and the Duschinsky rotation matrix elements are evaluated for the most strongly affected modes, nu17 and nu18. Several transitions in the oDFB-oDFB van der Waals dimer and oDFB-Ar complex are also assigned in the spectrum. Copyright 1998 Academic Press. PMID:9724580

Swinn; Kable

1998-09-01

459

L- and U-shaped heat pipes thermal modules with twin fans for cooling of electronic system under variable heat source areas  

NASA Astrophysics Data System (ADS)

This study utilizes a versatile superposition method with thermal resistance network analysis to design and experiment on a thermal module with embedded six L-shaped or two U-shaped heat pipes and plate fins under different fan speeds and heat source areas. This type of heat pipes-heat sink module successively transfer heat capacity from a heat source to the heat pipes, the heat sink and their surroundings, and are suitable for cooling electronic systems via forced convection mechanism. The thermal resistances contain all major components from the thermal interface through the heat pipes and fins. Thermal performance testing shows that the lowest thermal resistances of the representative L- and U-shaped heat pipes-heat sink thermal modules are respectively 0.25 and 0.17 °C/W under twin fans of 3,000 RPM and 30 × 30 mm2 heat sources. The result of this work is a useful thermal management method to facilitate rapid analysis.

Wang, Jung-Chang

2014-04-01

460

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) [Austin, TX

1996-01-01