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Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Increased protein synthesis by cells exposed to a 1,800-MHz radio-frequency mobile phone electromagnetic field, detected by proteome profiling  

Science Journals Connector (OSTI)

To investigate whether or not low intensity radio frequency electromagnetic field exposure (RF-EME) associated...

Christopher Gerner; Verena Haudek…

2010-08-01T23:59:59.000Z

2

Response of radio frequency superconducting quantum interference devices to electromagnetic interference  

SciTech Connect (OSTI)

A number of applications of high-temperature superconductor radio frequency superconducting quantum interference devices (rf SQUIDs) require a certain immunity of these sensors against electromagnetic interference (EMI). We have investigated effects of electromagnetic radiation in the high-frequency and ultrahigh-frequency range on various types of rf SQUIDs. It has been found that EMI of sufficient field strength reduces the voltage versus flux transfer function, and thus increases the flux noise of the SQUIDs. SQUIDs with a wire wound tank circuit coil have been found to be more sensitive to EMI than SQUIDs integrated into a superconducting microstrip resonator. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Mueck, M.; Dechert, J.; Gail, J.; Kreutzbruck, M.; Schoene, S.; Weidl, R. [Institut fuer Angewandte Physik, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)] [Institut fuer Angewandte Physik, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

1995-09-01T23:59:59.000Z

3

Enhancement of electromagnetic propagation through complex media for Radio Frequency Identification  

E-Print Network [OSTI]

In this thesis, I present and examine the fundamental limitations involved in Radio Frequency Identification (RFID) as well as provide a means to improve reader-tag communication in ultra high frequency RFID systems. The ...

Marti, Uttara P

2005-01-01T23:59:59.000Z

4

On the imaging of radio-frequency electromagnetic data forcross-borehole mineral exploration  

Science Journals Connector (OSTI)

......the subsurface. borehole|electromagnetic...determine future drilling or excavation targets...the Chinese JW-4 borehole electric-field...targets are rare. The large conductivity contrast...the transmitter borehole (Fig. 12). The...separations much larger than a characteristic......

L. Yu; M. Chouteau; D. E. Boerner; J. Wang

1998-11-01T23:59:59.000Z

5

Development of an international standard for electromagnetic interference (EMI)/radio frequency interference (RFI)  

SciTech Connect (OSTI)

This paper covers the development of an international standard that establishes the requirements for electromagnetic compatibility testing of instrumentation and control equipment supplied for use in systems important to safety at nuclear power plants. The standard lists the applicable IEC standards (principally the IEC 61000 series) which define the general test methods, and provides the necessary application-specific parameters and criteria to ensure that nuclear safety requirements are met. This standard was prepared with the leadership by the Russian National Committee representatives to the International Electrotechnical Commission (IEC). (authors)

Sarylov, V. [EMC Test Center, NUIT, FSUE RIPT, Moscow (Russian Federation); Shumov, S. [FSUE SEC SNIIP, Moscow (Russian Federation); Quinn, E. [ANS, Dana Point, CA (United States)

2006-07-01T23:59:59.000Z

6

Radio-Frequency and ELF Electromagnetic Energies: A handbook for health professionals  

Science Journals Connector (OSTI)

...the areas that are most objective. The important introductory chapter on general concepts is naive and confused. Simple, fundamental matters, such as the part of the Lorentz force law that pertains to magnetic fields, are mishandled, and the section called "Free-Space Impedance" is bizarre. Weaknesses... We live in a sea of electromagnetic fields. But the sea is shallow, and the fields are so minute that they are detectable only with sophisticated technology and are arguably undetectable by biologic systems and, hence, harmless. But a host of biologic ...

Adair R.K.

1995-11-09T23:59:59.000Z

7

Radio frequency accelerating cavity having slotted irises for damping certain electromagnetic modes  

DOE Patents [OSTI]

An accelerating cavity is disclosed having one or more iris structures mounted therein for strongly damping unwanted frequencies that are generated in the cavity by bunches of particles in a particle beam that is accelerated through the cavity during its operation. Each of the iris structures is characterized by containing a plurality of radial slots therein that extend from the central aperture through the iris member to the perimeter thereof. The outer end of each of the radial slots includes an enlarged portion that is effective to prevent undesired frequencies from being reflected back into the center aperture of the iris member. Waveguide means connect the outer ends of the radial slots to frequency damping means or to a dump or dumps. 17 figures.

Palmer, R.B.

1991-05-21T23:59:59.000Z

8

Radio frequency accelerating cavity having slotted irises for damping certain electromagnetic modes  

DOE Patents [OSTI]

An accelerating cavity having one or more iris structures mounted therein for strongly damping unwanted frequencies that are generated in the cavity by bunches of particles in a particle beam that is accelerated through the cavity during its operation. Each of the iris structures is characterized by containing a plurality of radial slots therein that extend from the central aperture through the iris member to the perimeter thereof. The outer end of each of the radial slots includes an enlarged portion that is effective to prevent undesired frequencies from being reflected back into the center aperture of the iris member. Waveguide means connect the outer ends of the radial slots to frequency damping means or to a dump or dumps.

Palmer, Robert B. (Shoreham, NY)

1991-01-01T23:59:59.000Z

9

Stabilized radio frequency quadrupole  

DOE Patents [OSTI]

Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

1984-12-25T23:59:59.000Z

10

Frequencies for Radio Astronomy  

Science Journals Connector (OSTI)

... must therefore be achieved through the combined action of three international scientific unions, IAU (astronomy), COSPAR (space) and URSI (radio), which jointly delegate members to an ... jointly delegate members to an Inter-Union Commission for the Allocation of Frequencies for Radio Astronomy and Space Science (IUCAF). This Commission discusses the scientific case for protecting various ...

F. G. SMITH

1970-10-31T23:59:59.000Z

11

Stabilized radio-frequency quadrupole  

DOE Patents [OSTI]

A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

1982-09-29T23:59:59.000Z

12

Microwave and Radio Frequency Workshop  

Broader source: Energy.gov [DOE]

At the Microwave and Radio Frequency Workshop (held in Long Beach, CA, on July 25, 2012), academic and industry experts discussed the existing and emerging electrotechnologies – such as microwave ...

13

Intelligent Radio Frequency (RF) Monitoring  

E-Print Network [OSTI]

? Intelligent Radio Frequency (RF) Monitoring ? 2009 Armstrong International, Inc. www.armstronginternational.com 2 ?Expect many enjoyable experiences!? David M. Armstrong Present Process Challenges ? Identifying a failure ? Procedure.... Armstrong Steam Trap Challenges ? Identifying a failure ? Manpower ? Location ? Magnitude of failure ? Energy loss ? Loss of heat transfer ? Justification for repair ? ?Speed of Implementation? ? Environmental concerns Manpower Location 4...

Kimbrough, B.

14

METHODS OF RADIO-FREQUENCY CURRENT DRIVE  

E-Print Network [OSTI]

METHODS OF RADIO-FREQUENCY CURRENT DRIVE N. J. FISCH* Princeton Plasma Physics Laboratory-670 Radio-frequency waves can penetrate thermonuclear plasmas, depositing momentum and energy with great. INTRODUCTION Using radio-frequency (rf) waves to drive the toroidal current in tokamak reactors is attractive

15

Photonic Radio-Frequency Phase Detector based on Radio-Frequency to Intermediate-Frequency Phase Mapping  

Science Journals Connector (OSTI)

A photonic radio-frequency phase detector based on radio-frequency (RF) to intermediate-frequency mapping is demonstrated, and the theoretical principle of the design is explained.

Sun, Dongning; Dong, Yi; Wang, Siwei; Xia, Zongyang; Xie, Weilin; Shi, Hongxiao; Yi, Lilin; Hu, Weisheng

16

Synchrotron Radiation at Radio Frequencies from Cosmic Ray Air Showers  

E-Print Network [OSTI]

We review some of the properties of extensive cosmic ray air showers and describe a simple model of the radio-frequency radiation generated by shower electrons and positrons as they bend in the Earth's magnetic field. We perform simulations by calculating the trajectory and radiation of a few thousand charged shower particles. The results are then transformed to predict the strength and polarization of the electromagnetic radiation emitted by the whole shower.

Denis A. Suprun; Peter W. Gorham; Jonathan L. Rosner

2003-06-06T23:59:59.000Z

17

Synchrotron Radiation at Radio Frequencies from Cosmic Ray Air Showers  

E-Print Network [OSTI]

We review some of the properties of extensive cosmic ray air showers and describe a simple model of the radio-frequency radiation generated by shower electrons and positrons as they bend in the Earth's magnetic field. We perform simulations by calculating the trajectory and radiation of a few thousand charged shower particles. The results are then transformed to predict the strength and polarization of the electromagnetic radiation emitted by the whole shower.

Suprun, D A; Rosner, Jonathan L; Suprun, Denis A.; Gorham, Peter W.; Rosner, Jonathan L.

2003-01-01T23:59:59.000Z

18

High power radio frequency attenuation device  

DOE Patents [OSTI]

A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

Kerns, Quentin A. (Bloomingdale, IL); Miller, Harold W. (Winfield, IL)

1984-01-01T23:59:59.000Z

19

Radio Frequency Identification : regulating information privacy protection  

E-Print Network [OSTI]

As applications of Radio Frequency Identification (RFID) become more profuse, the technology itself is stirring up some controversy. Due to its potential for amassing large amounts of information about both people and ...

Laufer, Deanna (Deanna Raquel)

2007-01-01T23:59:59.000Z

20

Resonant circuit which provides dual-frequency excitation for rapid cycling of an electromagnet  

DOE Patents [OSTI]

Disclosed is a novel ring-magnet control circuit that permits synchrotron repetition rates much higher than the frequency of the sinusoidal guide field of the ring magnet during particle acceleration. The control circuit generates sinusoidal excitation currents of different frequencies in the half waves. During radio-frequency acceleration of the synchrotron, the control circuit operates with a lower frequency sine wave and, thereafter, the electromagnets are reset with a higher-frequency half sine wave.

Praeg, W.F.

1982-03-09T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

STIMULATED ELECTROMAGNETIC EMISSIONS BY HIGH-FREQUENCY ELECTROMAGNETIC PUMPING OF THE  

E-Print Network [OSTI]

STIMULATED ELECTROMAGNETIC EMISSIONS BY HIGH-FREQUENCY ELECTROMAGNETIC PUMPING OF THE IONOSPHERIC.S.A. Abstract. A high frequency electromagnetic pump wave transmitted into the ionospheric plasma from the ground can stimulate electromagnetic radiation with frequencies around that of the ionospher- ically

22

Radio frequency communication system utilizing radiating transmission lines  

DOE Patents [OSTI]

A radio communication system for use in tunnels, mines, buildings or other shielded locations in which a pair of radiating transmission lines (30), (31) extend through such location in spaced coextensive relation to each other. Each transmission line (30), (31) has at least one unidirectional amplifier (32), (33) interposed therein with the sense of the unidirectional amplifier (32) of one transmission line (30) being opposite to the sense of the unidirectional amplifier (33) of the other transmission line (31). Each of the amplifiers (32), (33) has a gain which is less than the coupling loss between the transmission lines (30), (31). Two or more mobile transceivers (35) in the location served by the system are coupled to the transmission lines (30), (31) by electromagnetic wave propagation in space in order to communicate directly with each other at a given radio frequency within the frequency range of the system.

Struven, Warren C. (San Carlos, CA)

1984-01-01T23:59:59.000Z

23

LOFAR, a new low frequency radio telescope  

E-Print Network [OSTI]

LOFAR, the Low Frequency Array, is a large radio telescope consisting of approximately 100 soccer-field sized antenna stations spread over a region of 400 km in diameter. It will operate at frequencies from ~10 to 240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its superb sensitivity will allow for studies of a broad range of astrophysical topics, including reionisation, transient radio sources and cosmic rays, distant galaxies and AGNs. In this contribution a status rapport of the LOFAR project and an overview of the science case is presented.

H. J. A. Rottgering

2003-09-19T23:59:59.000Z

24

Heating mechanisms in radio-frequency-driven ultracold plasmas  

Science Journals Connector (OSTI)

Several mechanisms by which an external electromagnetic field influences the temperature of a plasma are studied analytically and specialized to the system of an ultracold plasma (UCP) driven by a uniform radio-frequency (rf) field. Heating through collisional absorption is reviewed and applied to UCPs. Furthermore, it is shown that the rf field modifies the three-body recombination process by ionizing electrons from intermediate high-lying Rydberg states and upshifting the continuum threshold, resulting in a suppression of three-body recombination. Heating through collisionless absorption associated with the finite plasma size is calculated in detail, revealing a temperature threshold below which collisionless absorption is ineffective.

P. W. Smorenburg; L. P. J. Kamp; O. J. Luiten

2012-06-20T23:59:59.000Z

25

Frequency spectrum analysis of electromagnetic waves radiated by electrical discharges  

Science Journals Connector (OSTI)

In this study, we analyzed the frequency spectrum of the electromagnetic waves radiated by an electric discharge as a basic method for developing an on-line diagnostic technique for power equipment installed inside closed-switchboards. In order to simulate ... Keywords: closed-switchboard, electromagnetic shielding room, electromagnetic wave, frequency spectrum, local discharge, series arc discharge

Hyeon-Kyu Cha; Sun-Jae Kim; Dae-Won Park; Gyung-Suk Kil

2011-03-01T23:59:59.000Z

26

Burst Radio-Frequency Excited Pulsed Hollow-Cathode Lamp  

Science Journals Connector (OSTI)

Transient emission characteristics of a hollow-cathode lamp driven by a pulsed current in combination with a radio-frequency burst signal are described. The radio-frequency field...

Araki, Tsutomu; Walters, John P; Minami, Shigeo

1980-01-01T23:59:59.000Z

27

A Framework for Radio Frequency Spectrum Measurement and Analysis  

E-Print Network [OSTI]

A Framework for Radio Frequency Spectrum Measurement and Analysis V. Rory Petty ITTC-FY2008-TR allocation and the burgeoning problem of spectrum scarcity have prompted an examination of how the radio frequency spectrum is utilized. The radio frequency spectrum is an important national resource that impacts

Kansas, University of

28

SOME UNSOLVED CHALLENGES IN RADIO-FREQUENCY HEATING AND  

E-Print Network [OSTI]

SOME UNSOLVED CHALLENGES IN RADIO-FREQUENCY HEATING AND CURRENT DRIVE N. J. FISCH* Princeton Plasma in the electronic version. I. INTRODUCTION There are many methods by which radio-frequency (rf) waves drive, 2013 doi:10.13182/FST13-682 Several unsolved challenges in radio-frequency heating and current drive

29

Rotating-radio-frequency ion traps T. Hasegawa*  

E-Print Network [OSTI]

rf ion trap, the rotating-radio-frequency rotating-rf trap, in which the motion of a charged particleRotating-radio-frequency ion traps T. Hasegawa* Department of Physics, Keio University, Kanagawa and Technology, Boulder, Colorado 80305, USA Received 9 July 2005; published 20 October 2005 We discuss a radio-frequency

30

Radio frequency (RF) heated supersonic flow laboratory  

SciTech Connect (OSTI)

A unique supersonic flow apparatus which employs an inductively-coupled, radio frequency (RF) torch to supply high enthalpy source gas to the nozzle inlet is described. The main features of this system are the plasma tube, a cooled nozzle assembly, and a combustion/expansion chamber with a heat exchanger. A description of these components with current test data is presented. In addition, a discussion of anticipated experiments utilizing this system is included.

Wantuck, P.; Watanabe, H.

1990-01-01T23:59:59.000Z

31

Impact of Mobile Transmitter Sources on Radio Frequency Wireless Energy Harvesting  

E-Print Network [OSTI]

1 Impact of Mobile Transmitter Sources on Radio Frequency Wireless Energy Harvesting Antonio Organization, Tata Consultancy Services, India. Abstract--Wireless energy harvesting sensor networks consti battery resource, but are able to re-charge themselves through directed electromagnetic energy transfer

Sanyal, Sugata

32

Two Phase Spectrum Sharing for Frequency-Agile Radio Networks  

E-Print Network [OSTI]

1 Two Phase Spectrum Sharing for Frequency-Agile Radio Networks Zhenhua Feng and Yaling Yang of modern radios. We solve a joint spectrum sharing and end-to-end rate control problems for general technologies (e.g. software defined radio and cognitive radios) enable more flexible spectrum access through

Ha, Dong S.

33

2010 Raj JainCSE574sWashington University in St. Louis Radio FrequencyRadio Frequency  

E-Print Network [OSTI]

. Louis RFID ReadersRFID Readers Sends a pulse of radio energy and listens for tags response Readers may24-1 ©2010 Raj JainCSE574sWashington University in St. Louis Radio FrequencyRadio Frequency;24-3 ©2010 Raj JainCSE574sWashington University in St. Louis What is RFID?What is RFID? Radio Frequency

Jain, Raj

34

Effect of resonance in external radio-frequency circuit on very high frequency plasma discharge  

SciTech Connect (OSTI)

A fully electromagnetic plasma model for an asymmetric capacitively coupled plasma discharge is used to understand the interaction between the external radio-frequency (rf) distributed circuit and the plasma. The plasma is excited using a 150 MHz rf source connected to the top electrode, the bottom electrode is connected to a shorted transmission line, and the electrodes are separated from the chamber walls through dielectric rings. Under typical conditions, the electron density peaks in the center of the plasma chamber due to the standing electromagnetic wave and the rf current from the top electrode primarily returns through the bottom electrode. When the electrical length of the bottom transmission line is adjusted such that it presents a large (open-circuit) impedance at the plasma chamber interface, the rf return current shifts from the bottom electrode to the chamber wall. As a consequence, the peak in electron density also moves from the center of the chamber toward its outer periphery.

Rauf, Shahid; Chen Zhigang; Collins, Ken [Applied Materials, Inc., 974 E. Arques Avenue, M/S 81517 Sunnyvale, California 94085 (United States)

2010-05-15T23:59:59.000Z

35

Definition: Frequency-Domain Electromagnetics Survey | Open Energy  

Open Energy Info (EERE)

Frequency-Domain Electromagnetics Survey Frequency-Domain Electromagnetics Survey Jump to: navigation, search Dictionary.png Frequency-Domain Electromagnetics Survey Frequency-domain electromagnetic techniques are continuous wave field methods which enable the mapping of the electrical conductivity of the subsurface through electromagnetic induction.[1] View on Wikipedia Wikipedia Definition Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829. Around 1830 to 1832, Joseph Henry made a similar discovery, but did not publish his findings until later. Faraday's

36

Definition: Frequency-Domain Electromagnetic Survey | Open Energy  

Open Energy Info (EERE)

Electromagnetic Survey Electromagnetic Survey Jump to: navigation, search Dictionary.png Frequency-Domain Electromagnetic Survey Frequency-domain electromagnetic techniques are continuous wave field methods which enable the mapping of the electrical conductivity of the subsurface through electromagnetic induction.[1] Also Known As Controlled-Source EM References ↑ http://library.seg.org/doi/pdf/10.1190/1.1441531 Ret LikeLike UnlikeLike You like this.Sign Up to see what your friends like. rieved from "http://en.openei.org/w/index.php?title=Definition:Frequency-Domain_Electromagnetic_Survey&oldid=591411" Category: Definitions What links here Related changes Special pages Printable version Permanent link Browse properties About us Disclaimers Energy blogs Linked Data Developer services

37

Radio frequency ion source operated with field effect transistor based radio frequency system  

SciTech Connect (OSTI)

Characteristics of radio frequency (RF) plasma production are investigated using a field effect transistor inverter power supply as an RF wave source. With the frequency of around 0.3 MHz, an electron density over 10{sup 18} m{sup -3} is produced in argon plasma. Although lower densities are obtained in hydrogen plasma, it drastically increased up to 5x10{sup 18} m{sup -3} with an axial magnetic field of around 100 G applied in the driver region. Effects of the magnetic field and gas pressure are investigated in the RF produced plasma with the frequency of several hundred kilohertz.

Ando, A.; Komuro, A.; Matsuno, T. [Department of Electrical Engineering, Tohoku University, Sendai 980-8759 (Japan); Tsumori, K.; Takeiri, Y. [National Institute for Fusion Science, Toki 509-5292 (Japan)

2010-02-15T23:59:59.000Z

38

The Gaseous Electronics Conference radio-frequency reference cell: A defined parallel-plate radio-frequency system for experimental  

E-Print Network [OSTI]

The Gaseous Electronics Conference radio-frequency reference cell: A defined parallel-plate radio-frequency publication 3 September1993) A "referencecell" for generatingradio-frequency(rf) glow dischargesin gasesat a frequencyof 13.56MHz is described.The referencecell provides an experimental platform for comparing plasma

Kushner, Mark

39

2006 Raj JainCSE574sWashington University in St. Louis Radio FrequencyRadio Frequency  

E-Print Network [OSTI]

18-1 ©2006 Raj JainCSE574sWashington University in St. Louis Radio FrequencyRadio Frequency;18-3 ©2006 Raj JainCSE574sWashington University in St. Louis What is RFID?What is RFID? ! Radio Frequency #. 96-bit block of read- only storage (ROM). " Read-write memory. " Tags may have embedded sensors (tire

Jain, Raj

40

An improved integrally formed radio frequency quadrupole  

DOE Patents [OSTI]

An improved radio frequency quadrupole is provided having an elongate housing with an elongate central axis and top, bottom and two side walls symmetrically disposed about the axis, and vanes formed integrally with the walls, the vanes each having a cross-section at right angles to the central axis which tapers inwardly toward the axis to form electrode tips spaced from each other by predetermined distances. Each of the four walls, and the vanes integral therewith, is a separate structural element having a central lengthwise plane passing through the tip of the vane, the walls having flat mounting surfaces at right angles to and parallel to the control plane, respectively, which are butted together to position the walls and vane tips relative to each other. 4 figs.

Abbott, S.R.

1987-10-05T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Trirotron: triode rotating beam radio frequency amplifier  

DOE Patents [OSTI]

High efficiency amplification of radio frequencies to very high power levels including: establishing a cylindrical cloud of electrons; establishing an electrical field surrounding and coaxial with the electron cloud to bias the electrons to remain in the cloud; establishing a rotating electrical field that surrounds and is coaxial with the steady field, the circular path of the rotating field being one wavelength long, whereby the peak of one phase of the rotating field is used to accelerate electrons in a beam through the bias field in synchronism with the peak of the rotating field so that there is a beam of electrons continuously extracted from the cloud and rotating with the peak; establishing a steady electrical field that surrounds and is coaxial with the rotating field for high-energy radial acceleration of the rotating beam of electrons; and resonating the rotating beam of electrons within a space surrounding the second field, the space being selected to have a phase velocity equal to that of the rotating field to thereby produce a high-power output at the frequency of the rotating field.

Lebacqz, Jean V. (Stanford, CA)

1980-01-01T23:59:59.000Z

42

Low Audio-frequency Electromagnetic Signals of Natural Origin  

Science Journals Connector (OSTI)

... a year ago, we undertook a programme of measurement of natural electromagnetic signals in the audio-frequency range 25-130 cycles/sec, with the view of gathering evidence concerning their ...

R. E. HOLZER; O. E. DEAL

1956-03-17T23:59:59.000Z

43

Method and apparatus for radio frequency ceramic sintering  

DOE Patents [OSTI]

Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents. 6 figures.

Hoffman, D.J.; Kimrey, H.D. Jr.

1993-11-30T23:59:59.000Z

44

Method and apparatus for radio frequency ceramic sintering  

DOE Patents [OSTI]

Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents.

Hoffman, Daniel J. (Oak Ridge, TN); Kimrey, Jr., Harold D. (Knoxville, TN)

1993-01-01T23:59:59.000Z

45

Frequency-Domain Electromagnetic Survey | Open Energy Information  

Open Energy Info (EERE)

Frequency-Domain Electromagnetic Survey Frequency-Domain Electromagnetic Survey Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Frequency-Domain Electromagnetic Survey Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Geophysical Techniques Exploration Sub Group: Electrical Techniques Parent Exploration Technique: Electromagnetic Profiling Techniques Information Provided by Technique Lithology: Detection of high-conductivity bodies in the subsurface. Stratigraphic/Structural: Hydrological: Thermal: Detection of the presence of a thermal anomaly through its resistivity signature. Cost Information Low-End Estimate (USD): 2,928.38292,838 centUSD 2.928 kUSD 0.00293 MUSD 2.92838e-6 TUSD / mile Median Estimate (USD): 4,505.20450,520 centUSD

46

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

E-Print Network [OSTI]

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

Daniel, Luca

47

Electromagnetic source localization with finite set of frequency measurements  

E-Print Network [OSTI]

A phase conjugation algorithm for localizing an extended radiating electromagnetic source from boundary measurements of the electric field is presented. Measurements are taken over a finite number of frequencies. The artifacts related to the finite frequency data are tackled with $l_1-$regularization blended with the fast iterative shrinkage-thresholding algorithm with backtracking of Beck & Teboulle.

Abdul Wahab; Amer Rasheed; Rab Nawaz; Saman Anjum

2014-09-16T23:59:59.000Z

48

High-power radio-frequency attenuation device  

DOE Patents [OSTI]

A resistor device for attenuating radio frequency power includes a radio frequency conductor connected to a series of fins formed of high relative magnetic permeability material. The fins are dimensional to accommodate the skin depth of the current conduction therethrough, as well as an inner heat conducting portion where current does not travel. Thermal connections for air or water cooling are provided for the inner heat conducting portions of each fin. Also disclosed is a resistor device to selectively alternate unwanted radio frequency energy in a resonant cavity.

Kerns, Q.A.; Miller, H.W.

1981-12-30T23:59:59.000Z

49

New design of a radio-frequency plasma torch  

Science Journals Connector (OSTI)

A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a radio-frequency (rf) plasma torch. The method employed here is based ... rates without interfering with the...

Toyonobu Yoshida; Kunihiko Nakagawa…

1981-03-01T23:59:59.000Z

50

Radio-frequency-excited carbon dioxide metal waveguide laser  

Science Journals Connector (OSTI)

A new type of waveguide laser is described in which a single-surface concave metal waveguide also doubles as the grounded electrode in a radio-frequency-excited gaseous discharge. The...

Grossman, Jonathan G; Casperson, Lee W; Stafsudd, Oscar M

1983-01-01T23:59:59.000Z

51

Radio frequency identification enabled wireless sensing for intelligent food logistics  

Science Journals Connector (OSTI)

...Hoekstra, Bastien Chopard and Peter Coveney Radio frequency identification enabled wireless sensing for intelligent food logistics Zhuo Zou Qiang Chen Ismail Uysal Lirong Zheng Phil. Trans. R. Soc. A 372, 20130313 (13 June 2014; Published online...

2014-01-01T23:59:59.000Z

52

Radio frequency overview of the high explosive radio telemetry project  

SciTech Connect (OSTI)

High explosive radio telemetry (HERT) is a project that is being developed jointly by Los Alamos National Laboratory and AlliedSignal Federal Manufacturing and Technologies. The ultimate goal is to develop a small, modular telemetry system capable of high-speed detection of explosive events, with an accuracy on the order of 10 nanoseconds. The reliable telemetry of this data, from a high-speed missile trajectory, is a very challenging opportunity. All captured data must be transmitted in less than 20 microseconds of time duration. This requires a high bits/Hertz microwave telemetry modulation code to insure transmission of the data with the limited time interval available.

Bracht, R. [Los Alamos National Lab., NM (United States); Dimsdle, J.; Rich, D.; Smith, F. [AlliedSignal Federal Manufacturing and Technologies, Kansas City, MO (United States)

1998-12-31T23:59:59.000Z

53

Dual radio frequency plasma source: Understanding via electrical asymmetry effect  

SciTech Connect (OSTI)

On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies ({xi}), ourstudies also predict local maxima for odd integer values of 2{xi} as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources.

Bora, B. [Departamento de Plasma Termonuclear, Comision Chilena de Energia Nuclear (CCHEN), Casilla 188-D, Santiago (Chile); Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Bhuyan, H.; Favre, M.; Wyndham, E. [Departamento de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Wong, C. S. [Plasma Technology Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2013-04-21T23:59:59.000Z

54

Method and Apparatus for Pasteurizing Shell Eggs Using Radio Frequency  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Method and Apparatus for Pasteurizing Shell Eggs Using Radio Frequency Method and Apparatus for Pasteurizing Shell Eggs Using Radio Frequency Heating" Inventors..--.. Christopher D. Brunkhorst, David J. Geveke, Andrew B. W. Bigley. This disclosure is directed to a system for pasteurizing shell eggs. The system includes an egg rotating assembly structured to rotate the egg, and electrodes that are in contact with the egg. The system is structured so that, as the rotating assembly rotates the egg, radio frequency energy is directed to the egg to pasteurize it. Nearly 200 million "shell eggs" are consumed in the United States (US) each day. "Shell eggs" are non-powdered conventional eggs that are naturally produced by hens. Shell eggs are among the most nutritious foods on earth and can be part of a healthy diet. However, some unbroken, clean, fresh

55

Low frequency radio spectrum and spectral turnover of LS 5039  

E-Print Network [OSTI]

LS 5039, a possible black hole x-ray binary, was recently observed with Giant Meterwave Radio Telescope. The observed spectrum presented here shows that the spectrum is inverted at the low frequency. When combined with the archival data with orbital phase similar to the present observations, it shows a clear indication of a spectral turnover. The combined data are fitted with a broken power-law and the break frequency signifies a possible spectral turnover of the spectrum around 964 MHz. Truly simultaneous observations in radio wavelength covering a wide range of frequencies are required to fix the spectrum and the spectral turn over which will play a crucial role in developing a deeper understanding of the radio emitting jet in LS 5039.

Sagar Godambe; Subir Bhattacharyya; Nilay Bhatt; Manojendu Choudhury

2008-07-15T23:59:59.000Z

56

Method for imaging with low frequency electromagnetic fields  

DOE Patents [OSTI]

A method is described for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The travel times corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter [alpha] for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography. 13 figures.

Lee, K.H.; Xie, G.Q.

1994-12-13T23:59:59.000Z

57

Method for imaging with low frequency electromagnetic fields  

DOE Patents [OSTI]

A method for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The traveltimes corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter .alpha. for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography.

Lee, Ki H. (Lafayette, CA); Xie, Gan Q. (Berkeley, CA)

1994-01-01T23:59:59.000Z

58

Plasma Paramagnetism in Radio-Frequency Fields  

Science Journals Connector (OSTI)

A study by experiment, simulation, and theory has found that a plasma responds paramagnetically to the external rf magnetic field applied perpendicular to the static magnetic field with frequency ?frequency. This effect can be exploited in the rf plugging and heating of plasmas; it explains the earlier rf plugging experiment (type-3 coil) of Watari et al. at Nagoya and possibly the rf heating experiment of Dikii et al. on the Uragan stellarator.

Y. Ohsawa; M. Inutake; T. Tajima; T. Hatori; T. Kamimura

1979-10-22T23:59:59.000Z

59

The characteristics of atmospheric radio frequency discharges with frequency increasing at a constant power density  

SciTech Connect (OSTI)

A computational model is used to investigate the characteristics of atmospheric radio frequency discharges by increasing frequency from 20 to 100 MHz at a constant power density. The simulation results show that increasing frequency can effectively enhance electron density before the transition frequency but after it the ignition is quenched then the electron density decreases. However this simulation also indicates the maximum time-averaged electron energy reduces monotonically with the excitation frequency increasing at a constant power density.

Zhang Yuantao; Li Qingquan; Lou Jie; Li Qingmin [School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China)

2010-10-04T23:59:59.000Z

60

Theory of shear suppression of edge turbulence by externally driven radio-frequency waves  

Science Journals Connector (OSTI)

Here, we propose and analyze a technique for active suppression of tokamak edge turbulence. Suppression occurs due to the effects of a sheared radial electric field generated by externally driven radio-frequency waves. Plasma flow is induced by radially varying wave-driven Reynolds and magnetic stresses, and opposed by neoclassical damping. For Alfvénic flow drive, the predicted shear flow profile is determined by ion inertia and electron dissipation effects. Results indicate that a modest amount of absorbed power is required for edge-turbulence suppression. More generally, several novel results in the theory of momentum transport by electromagnetic fluctuations are presented.

G. G. Craddock and P. H. Diamond

1991-09-16T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Emission of Radio-Frequency Waves from Plasmas  

Science Journals Connector (OSTI)

Observations of the radio-frequency emission from extraterrestrial plasmas and plasmas produced in the laboratory are described and various attempts at interpretation of the results are reviewed. Estimates are made of the probable loss of radiant energy from plasmas in proposed thermonuclear reactors.

G. Bekefi; Sanborn C. Brown

1961-01-01T23:59:59.000Z

62

Localized radio frequency communication using asynchronous transfer mode protocol  

DOE Patents [OSTI]

A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.

Witzke, Edward L. (Edgewood, NM); Robertson, Perry J. (Albuquerque, NM); Pierson, Lyndon G. (Albuquerque, NM)

2007-08-14T23:59:59.000Z

63

"Magic" radio-frequency dressing for trapped atomic microwave clocks  

E-Print Network [OSTI]

It has been proposed to use magnetically trapped atomic ensembles to enhance the interrogation time in microwave clocks. To mitigate the perturbing effects of the magnetic trap, "near-magic field" configurations are employed, where the involved clock transition becomes independent of the atoms potential energy to first order. Still, higher order effects are a dominating source for dephasing, limiting the perfomance of this approach. Here we propose a simple method to cancel the energy dependence to both, first and second order, using weak radio-frequency dressing. We give values for dressing frequencies, amplitudes, and trapping fields for 87Rb atoms and investigate quantitatively the robustness of these "second-order magic" conditions to variations of the system parameters. We conclude that radio-frequency dressing can suppress field-induced dephasing by at least one order of magnitude for typical experimental parameters.

Kazakov, Georgy A

2014-01-01T23:59:59.000Z

64

Radio Frequency Diesel Particulate Filter Sensor Reduces Fuel Consumption, Wins R&D 100 Award  

Office of Energy Efficiency and Renewable Energy (EERE)

Radio Frequency Diesel Particulate Filter Sensor (RF-DPF) is a sensor that uses radio frequencies to measure the amount and distribution of soot and ash in the filters that remove particulate matter from the exhaust of diesel engines.

65

Temporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath  

E-Print Network [OSTI]

and within a radio-frequency (RF) biased plasma sheath is studied experimentally with a pulsed laserTemporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath B; therefore, radio-frequency (RF) biases which result in zero net electrical current to the substrate

California at Los Angles, University of

66

Terahertz bandwidth integrated radio frequency spectrum analyzer via nonlinear optics  

E-Print Network [OSTI]

We report an integrated all-optical radio frequency spectrum analyzer based on a ~ 4cm long doped silica glass waveguide, with a bandwidth greater than 2.5 THz. We use this device to characterize the intensity power spectrum of ultrahigh repetition rate mode-locked lasers at repetition rates up to 400 GHz, and observe dynamic noise related behavior not observable with other techniques.

Ferrera, Marcello; Pasquazi, Alessia; Peccianti, Marco; Clerici, Matteo; Caspani, Lucia; Chu, Sai T; Little, Brent E; Morandotti, Roberto; Moss, David J

2014-01-01T23:59:59.000Z

67

Longitudinal capture in the radio-frequency-quadrupole structure  

SciTech Connect (OSTI)

The radio-frequency-quadrupole (RFQ) linac structure not only can attain easily transverse focusing in the low-beta region, but also can obtain very high capture efficiency because of its low beta-lambda and low-particle rigidity. An optimization study of the zero space-charge longitudinal capture in an RFQ linac that yields configurations with large capture efficiency is described.

Inagaki, S.

1980-03-01T23:59:59.000Z

68

Elimination of Radio-Frequency Noise by Identifying and Diverting Large RF Ground Currents  

SciTech Connect (OSTI)

The problem of electromagnetic interference in scientific instruments is compounded for high-power plasma experiments by the large currents and voltages as well as by the broad bandwidths of the instruments. Ground loops are known to allow stray magnetic fields to drive large ground currents that can induce spurious signals and damage electronics. Furthermore, even when a ground loop is broken, capacitive coupling can still permit the flow of radio-frequency current, resulting in high-frequency spurious signals that can overwhelm the desired signal. We present the effects of RF ground loops on the output of vacuum photodiodes used in the Caltech Solar Loop Experiment and demonstrate the elimination of the spurious signals by diverting the ground currents away from the most vulnerable point of the signal line. Techniques for identifying the RF ground loops are also discussed. These techniques should be valuable in many high-power systems where interference from spurious coupling is an issue.

Perkins, R. J.; Bellan, P. M. [Applied Physics, California Institute of Technology (United States)

2011-12-23T23:59:59.000Z

69

Frequency-domain multiscale quantum mechanics/electromagnetics simulation method  

SciTech Connect (OSTI)

A frequency-domain quantum mechanics and electromagnetics (QM/EM) method is developed. Compared with the time-domain QM/EM method [Meng et al., J. Chem. Theory Comput. 8, 1190–1199 (2012)], the newly developed frequency-domain QM/EM method could effectively capture the dynamic properties of electronic devices over a broader range of operating frequencies. The system is divided into QM and EM regions and solved in a self-consistent manner via updating the boundary conditions at the QM and EM interface. The calculated potential distributions and current densities at the interface are taken as the boundary conditions for the QM and EM calculations, respectively, which facilitate the information exchange between the QM and EM calculations and ensure that the potential, charge, and current distributions are continuous across the QM/EM interface. Via Fourier transformation, the dynamic admittance calculated from the time-domain and frequency-domain QM/EM methods is compared for a carbon nanotube based molecular device.

Meng, Lingyi; Yin, Zhenyu; Yam, ChiYung, E-mail: yamcy@yangtze.hku.hk, E-mail: ghc@everest.hku.hk; Koo, SiuKong; Chen, GuanHua, E-mail: yamcy@yangtze.hku.hk, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong)] [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong); Chen, Quan; Wong, Ngai [Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)] [Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)

2013-12-28T23:59:59.000Z

70

Radio frequency coupling apparatus and method for measuring minority carrier lifetimes in semiconductor materials  

DOE Patents [OSTI]

An apparatus for measuring the minority carrier lifetime of a semiconductor sample using radio-frequency coupling. The measuring apparatus includes an antenna that is positioned a coupling distance from a semiconductor sample which is exposed to light pulses from a laser during sampling operations. A signal generator is included to generate high frequency, such as 900 MHz or higher, sinusoidal waveform signals that are split into a reference signal and a sample signal. The sample signal is transmitted into a sample branch circuit where it passes through a tuning capacitor and a coaxial cable prior to reaching the antenna. The antenna is radio-frequency coupled with the adjacent sample and transmits the sample signal, or electromagnetic radiation corresponding to the sample signal, to the sample and receives reflected power or a sample-coupled-photoconductivity signal back. To lower impedance and speed system response, the impedance is controlled by limiting impedance in the coaxial cable and the antenna reactance. In one embodiment, the antenna is a waveguide/aperture hybrid antenna having a central transmission line and an adjacent ground flange. The sample-coupled-photoconductivity signal is then transmitted to a mixer which also receives the reference signal. To enhance the sensitivity of the measuring apparatus, the mixer is operated to phase match the reference signal and the sample-coupled-photoconductivity signal.

Johnston, Steven W. (Golden, CO); Ahrenkiel, Richard K. (Lakewood, CO)

2002-01-01T23:59:59.000Z

71

Three-Dimensional Electromagnetic High Frequency Axisymmetric Cavity Scars.  

SciTech Connect (OSTI)

This report examines the localization of high frequency electromagnetic fi elds in three-dimensional axisymmetric cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This report treats both the case where the opposing sides, or mirrors, are convex, where there are no interior foci, and the case where they are concave, leading to interior foci. The scalar problem is treated fi rst but the approximations required to treat the vector fi eld components are also examined. Particular att ention is focused on the normalization through the electromagnetic energy theorem. Both projections of the fi eld along the scarred orbit as well as point statistics are examined. Statistical comparisons are m ade with a numerical calculation of the scars run with an axisymmetric simulation. This axisymmetric cas eformstheoppositeextreme(wherethetwomirror radii at each end of the ray orbit are equal) from the two -dimensional solution examined previously (where one mirror radius is vastly di ff erent from the other). The enhancement of the fi eldontheorbitaxiscanbe larger here than in the two-dimensional case. Intentionally Left Blank

Warne, Larry K.; Jorgenson, Roy E.

2014-10-01T23:59:59.000Z

72

SUBJECT: Effective Date: Policy Number: Radio Frequency Spectrum 12-15-10 4-011  

E-Print Network [OSTI]

SUBJECT: Effective Date: Policy Number: Radio Frequency Spectrum 12-15-10 4-011 Supersedes: Page. POLICY STATEMENT: Radio frequency spectrum is a critical resource that must be managed to eliminate be approved by UCF Computer Services & Telecommunications to provide spectrum coordination and avoid radio

Glebov, Leon

73

Characterization of microstructure with low frequency electromagnetic techniques  

SciTech Connect (OSTI)

A new computational method for characterizing the relationship between surface crystallography and electrical conductivity in anisotropic materials with low frequency electromagnetic techniques is presented. The method is discussed from the standpoint of characterizing the orientation of a single grain, as well as characterizing statistical information about grain ensembles in the microstructure. Large-area electron backscatter diffraction (EBSD) data was obtained and used in conjunction with a synthetic aperture approach to simulate the eddy current response of beta annealed Ti-6Al-4V. Experimental eddy current results are compared to the computed eddy current approximations based on electron backscatter diffraction (EBSD) data, demonstrating good agreement. The detectability of notches in the presence of noise from microstructure is analyzed with the described simulation method and advantages and limitations of this method are discussed relative to other NDE techniques for such analysis.

Cherry, Matthew R.; Sathish, Shamachary [University of Dayton Research Institute, Structural Integrity Division, 300 College Park, Dayton, OH 45469-0020 (United States); Pilchak, Adam L.; Blodgett, Mark P. [Air Force Research Laboratory, Materials and Manufacturing Directorate (AFRL/RXCM), 2230 10th St., WPAFB, OH 45433 (United States); Cherry, Aaron J. [Southwest Ohio Council for Higher Education, 3155 Research Blvd., Suite 204, Dayton, OH 45420-4015 (United States)

2014-02-18T23:59:59.000Z

74

Hermetic aluminum radio frequency interconnection and method for making  

DOE Patents [OSTI]

The present invention provides a light-weight, hermetic coaxial radio-frequency (RF) interconnection having an electrically conductive outer housing made of aluminum or an aluminum alloy, a central electrical conductor made of ferrous or non-ferrous material, and a cylinder of dielectric material comprising a low-melting-temperature, high-thermal-expansion aluminophosphate glass composition for hermetically sealing between the aluminum-alloy outer housing and the ferrous or non-ferrous center conductor. The entire RF interconnection assembly is made permanently hermetic by thermally fusing the center conductor, glass, and housing concurrently by bringing the glass to the melt point by way of exposure to an atmospheric temperature sufficient to melt the glass, less than 540.degree. C., but that does not melt the center conductor or the outer aluminum or aluminum alloy housing. The composition of the glass used is controlled to provide a suitable low dielectric constant so that an appropriate electrical characteristic impedance, for example 50 ohms, can be achieved for an electrical interconnection that performs well at high radio frequencies and also provides an interconnection maintaining a relatively small physical size.

Kilgo, Riley D. (Albuquerque, NM); Kovacic, Larry (Albuquerque, NM); Brow, Richard K. (Rolla, MO)

2000-01-01T23:59:59.000Z

75

Two-Dimensional Numerical Modeling of Radio-Frequency Ion Engine Discharge  

E-Print Network [OSTI]

Two-Dimensional Numerical Modeling of Radio-Frequency Ion Engine Discharge Michael Meng-Tsuan Tsay-Frequency Ion Engine Discharge Michael Meng-Tsuan Tsay, Manuel Martinez-Sanchez August 2010 SSL # 14 Modeling of Radio-Frequency Ion Engine Discharge by Michael Meng-Tsuan Tsay Submitted to the Department

76

Effect of radio frequency discharge power on dusty plasma parameters  

SciTech Connect (OSTI)

The parameters of a two-dimensional dusty plasma consisting of six, 9 mum diameter particles trapped inside a radio frequency (rf) plasma sheath have been measured as a function of rf power in a 13.5 mtorr (1.8 Pa) argon discharge. The center-of-mass and breathing frequencies are found by projecting the cluster's Brownian motion onto the associated normal mode. The center-of-mass frequency (i.e., radial confinement) is insensitive to rf power. The Debye shielding parameter kappa, as found from the breathing frequency, increases from approx =0.5 to 2 as the square root of rf power. The Debye length decreases from approx =2.7 to 0.7 mm as the inverse of the square root of rf power. The average particle charge qapprox =-17 000e is effectively independent of rf power. These results are consistent with an electron temperature that is independent of rf power and an ion density that is directly proportional to rf power, where the Debye length is determined by the ion density in combination with the electron temperature.

Sheridan, T. E. [Department of Physics and Astronomy, Ohio Northern University, Ada, Ohio 45810 (United States)

2009-08-01T23:59:59.000Z

77

Influence of excitation frequency on plasma parameters and etching characteristics of radio-frequency discharges  

Science Journals Connector (OSTI)

Abstract Plasma parameters such as electron density, electron-collision rate, resonance frequency and the bias voltage were shown to be important for the characterization of radio-frequency (RF) plasmas. By means of self-excited electron resonance spectroscopy (SEERS), the plasma parameters were compared at two different frequencies, 13.56 \\{MHz\\} and 40.68 MHz, in argon, oxygen, fluorine and their mixtures at low pressure. Upon increasing the generator frequency, more RF power has to be applied to achieve the same bias voltage. At the lower pressure, the bias voltage indicates the mean energy of the ions impacting on the substrate and causing damage at the surface. The experimental results show that generally more power was dissipated in the plasma instead of the sheath if the frequency of the substrate generator was decreased. This results in a significantly higher electron density at the higher frequency. The increase of mean ion energy, owing to lower sheath thickness, has to be taken into account as a second-order effect. In order to show the influence of frequency for process applications, the etch rate of SiO2 on silicon was determined in CF4. For the same generator power, there is no well-pronounced dependence of the etch rate of SiO2 on silicon (CF4) on the frequency. For the same bias voltage, the etch rate of SiO2 increases roughly with the frequency.

M. Klick; L. Eichhorn; W. Rehak; M. Kammeyer; H. Mischke

1999-01-01T23:59:59.000Z

78

Radio-frequency probes of Antarctic ice at South Pole  

E-Print Network [OSTI]

System Sciences O p e n A cce ss Discussions Radio-frequency probes of Antarctic ice at South Pole D. Besson1 and I. Kravchenko2 1University of Kansas, Department of Physics and Astronomy, Lawrence, KS 66045-7582, USA 2University of Nebraska – Lincoln... to successive waveforms. Each 0.5 meter division horizontally corresponds to approximately 5 ns. -20 -10 0 10 20 Rx v ol ta ge ( V, a ft er s ca li ng ; of fs e Time (ns, relative) 6 us echo (Vx1) 9.6 us echo (Vx1.3) 13.9 us echo (Vx3.5) 17.2 us echo (Vx10...

Besson, David Zeke; Kravchenko, I.

2013-05-16T23:59:59.000Z

79

Radio-frequency glow discharge spectrometry:: A critical review  

Science Journals Connector (OSTI)

This paper presents a critical review of analytical radio frequency glow discharge spectrometry (rf-GDS). The historical foundations of rf-GDS are described, and current knowledge of the fundamental physics of analytical rf glow discharges is discussed. Additionally, instrumentation, methodologies, and applications of rf glow discharge optical emission spectrometry (rf-GDOES) and mass spectrometry (rf-GDMS) are reviewed. Although other rf-GDS techniques have appeared [e.g. rf glow discharge atomic absorption spectrophotometry (rf-GDAAS)], the emphasis is placed upon rf-GDOES and rf-GDMS, because they have received by far the most interest from analytical chemical metrologists. This review also provides explanations of some developments that are needed for further progress in the field of analytical rf-GDS.

Michael R. Winchester; Richard Payling

2004-01-01T23:59:59.000Z

80

Binary high-frequency-carrier diffractive optical elements: electromagnetic theory  

Science Journals Connector (OSTI)

Using rigorous electromagnetic diffraction theory, we evaluate the potential performance and the limitations of coding diffractive optical elements in the form of a...

Noponen, Eero; Turunen, Jari

1994-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Self-consistent modeling of radio-frequency plasma generation in stellarators  

Science Journals Connector (OSTI)

A self-consistent model of radio-frequency (RF) plasma generation in stellarators in the ion cyclotron frequency range is described. The model includes equations ... of electron energy balance takes into account ...

V. E. Moiseenko; Yu. S. Stadnik; A. I. Lysoivan; V. B. Korovin

2013-11-01T23:59:59.000Z

82

A multibeam radio-frequency ion source with a discharge chamber inside a resonator  

Science Journals Connector (OSTI)

The design of a multibeam ion source with a discharge chamber inside a half-wavelength radio-frequency (RF) resonator with a spiral load ... resonator. The RF oscillator operating at a frequency of 38 MHz is grou...

B. Yu. Bogdanovich; V. P. Zubovskii…

2008-09-01T23:59:59.000Z

83

Tabu Search for Frequency Assignment in Mobile Radio Networks \\Lambda  

E-Print Network [OSTI]

in a regular spiral pattern to minimize the electromagnetic interference between adjacent pairs · Often used foil or braid to insulate the pair from electromagnetic interference · UTP (unshielded twisted pair

Hao, Jin-Kao

84

The driving frequency effects on the atmospheric pressure corona jet plasmas from low frequency to radio frequency  

Science Journals Connector (OSTI)

Lately the atmospheric pressure jet type coronaplasma which has been typically driven by dc to low frequency (LF: several tens of kHz) is often generated by using radio frequency of 13.56 MHz. Yet the relationship between the plasma and its driving frequency has seldom been investigated. Hence in this study dependence of the atmospheric pressurecoronaplasmacharacteristics on the driving frequency was explored experimentally from LF to rf (5 kHz–13.56 MHz). The plasmas generated by the driving frequency under 2 MHz were cylindrical shape of several tens of millimeters long while the 13.56 MHz plasma is spherical and a few millimeters long. As the driving frequency was increased the plasma length became shortened. At the lower driving frequencies (below 2 MHz) the plasmas existed as positive streamer and negative glow for each half period of the applied voltage but the discharge was more continuous in time for the 13.56 MHz plasma. It was inferred from the measured I–V curves that the higher driving frequency induced higher discharge currents and the gas temperature was increased as the driving frequency was increased.

Dan Bee Kim; H. Jung; B. Gweon; S. Y. Moon; J. K. Rhee; W. Choe

2011-01-01T23:59:59.000Z

85

Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using the  

E-Print Network [OSTI]

Detectability of Radio Frequency Interference due to Spread Spectrum Communication Signals using-- Analysis of detectability of the kurtosis algorithm for pulsed-sinusoidal Radio Frequency Interference (RFI) has already been performed in detail. The detectability for wide- band spread-spectrum RFI

Ruf, Christopher

86

An intelligent approach to handle False-Positive Radio Frequency Identification Anomalies  

Science Journals Connector (OSTI)

Radio Frequency Identification RFID technology allows wireless interaction between tagged objects and readers to automatically identify large groups of items. This technology is widely accepted in a number of application domains, however, it suffers ... Keywords: Bayesian Network, False-Positive Anomaly, Neural Network, Non-Monotonic Reasoning, Radio Frequency Identification --Rfid

Peter Darcy; Bela Stantic; Abdul Sattar

2011-11-01T23:59:59.000Z

87

Single-cycle radio-frequency pulse generation by an optoelectronic  

E-Print Network [OSTI]

Single-cycle radio-frequency pulse generation by an optoelectronic oscillator Etgar C. Levy,1-locking of an optoelectronic oscillator which generates a single-cycle radio-frequency pulse train. The measured pulse to pulse by a passive mode-locked oscillator. The passive mode-locked optoelectronic oscillator is important

Horowitz, Moshe

88

Large area radio frequency plasma for microelectronics processing Z. Yu and D. Shaw  

E-Print Network [OSTI]

focus on wide area plasma uniformity and undesired antenna window erosion caused by the plasma. OurLarge area radio frequency plasma for microelectronics processing Z. Yu and D. Shaw Colorado State November 1994 Radio-frequency rf inductively coupled planar plasma ICP provides a better way to generate

Collins, George J.

89

Resonant-frequency discharge in a multi-cell radio frequency cavity  

SciTech Connect (OSTI)

We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problems related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.

Popovic, S; Upadhyay, J.; Mammosser, J.; Nikolic, M; Vuskovic, L

2014-11-07T23:59:59.000Z

90

Effects of radio frequency bias frequency and radio frequency bias pulsing on SiO{sub 2} feature etching in inductively coupled fluorocarbon plasmas  

SciTech Connect (OSTI)

The effect of radio frequency (rf) bias frequency on SiO{sub 2} feature etching using inductively coupled fluorocarbon plasmas is investigated. It is found that the rf bias frequency can have an important effect on SiO{sub 2} feature etch rate, microtrenching phenomena, and SiO{sub 2}-to-photoresist etch selectivity. In addition, the effect of rf bias pulsing on inductively coupled fluorocarbon plasma SiO{sub 2} etching has been studied and a model that describes the data well is presented. The model assumes that fluorocarbon deposition occurs while the rf bias is off, fluorocarbon etching occurs during the first part of time that the bias is on, and substrate etching occurs once the fluorocarbon material has been removed from the substrate. (c) 2000 American Vacuum Society.

Schaepkens, M. [Physics Department, University at Albany, Albany, New York 12222 (United States)] [Physics Department, University at Albany, Albany, New York 12222 (United States); Oehrlein, G. S. [Physics Department, University at Albany, Albany, New York 12222 (United States)] [Physics Department, University at Albany, Albany, New York 12222 (United States); Cook, J. M. [Lam Research Corporation, Fremont, California 94538-6470 (United States)] [Lam Research Corporation, Fremont, California 94538-6470 (United States)

2000-03-01T23:59:59.000Z

91

Chapter 1.6.7 - Biological Effects of Radio-Frequency Fields  

Science Journals Connector (OSTI)

Publisher Summary This chapter discusses the biological effect of radio-frequency (rf) fields. It has initiated many investigations on biological effects of low-level electromagnetic fields. The aim of the chapter is to present a critical review of the current knowledge of the effects of rf fields on biological systems and to introduce various setups designed to test the influence of rf fields on these systems especially for the mobile communication frequency range (200 \\{MHz\\} to 2.5 GHz). In experiments whose aim is to test the effects of rf fields on technical or biological systems, the design of the exposure setup is a very important step. Insufficient knowledge of the field distribution inside the specimen will lead to wrong results. Independent of the outcome itself, wrong positive as well as wrong negative results may be the consequence and the experimental work and the money invested will be wasted. Testing the effects of rf fields on biological systems needs both detailed knowledge about the actual field distribution inside the specimen and well-documented reliable biological processes whose potential changes may finally be put down to the presence of an rf field.

R. Meyer; J. Streckert; V. Hansen

2002-01-01T23:59:59.000Z

92

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect (OSTI)

Ceralink Inc. developed FastFuse™, a rapid, new, energy saving process for lamination of glass and composites using radio frequency (RF) heating technology. The Inventions and Innovations program supported the technical and commercial research and development needed to elevate the innovation from bench scale to a self-supporting technology with significant potential for growth. The attached report provides an overview of the technical and commerical progress achieved for FastFuse™ during the course of the project. FastFuse™ has the potential to revolutionize the laminate manufacturing industries by replacing energy intensive, multi-step processes with an energy efficient, single-step process that allows higher throughput. FastFuse™ transmits RF energy directly into the interlayer to generate heat, eliminating the need to directly heat glass layers and the surrounding enclosures, such as autoclaves or vacuum systems. FastFuse™ offers lower start-up and energy costs (up to 90% or more reduction in energy costs), and faster cycles times (less than 5 minutes). FastFuse™ is compatible with EVA, TPU, and PVB interlayers, and has been demonstrated for glass, plastics, and multi-material structures such as photovoltaics and transparent armor.

Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

2009-11-11T23:59:59.000Z

93

Radio-frequency quadrupole vane-tip geometries  

SciTech Connect (OSTI)

Radio-frequency quadrupole (RFQ) linacs are becoming widely accepted in the accelerator community. They have the remarkable capability of simultaneously bunching low-energy ion beams and accelerating them to energies at which conventional accelerators can be used, accomplishing this with high-transmission efficiencies and low-emittance growths. The electric fields, used for radial focusing, bunching, and accelerating, are determined by the geometry of the vane tips. The choice of the best vane-tip geometry depends on considerations such as the peak surface electric field, per cent of higher multipole components, and ease of machining. We review the vane-tip geometry based on the ideal two-term potential function and briefly describe a method for calculating the electric field components in an RFQ cell with arbitrary vane-tip geometry. We describe five basic geometries and use the prototype RFQ design for the Fusion Materials Irradiation Test (FMIT) accelerator as an example to compare the characteristics of the various geometries.

Crandall, K.R.; Mills, R.S.; Wangler, T.P.

1983-01-01T23:59:59.000Z

94

Method of making radio frequency ion source antenna  

DOE Patents [OSTI]

In the method, the radio frequency (RF) antenna is made by providing a clean coil made of copper tubing or other metal conductor, which is coated with a tacky organic binder, and then with a powdered glass frit, as by sprinkling the frit uniformly over the binder. The coil is then heated internally in an inert gas atmosphere, preferably by passing an electrical heating current along the coil. Initially, the coil is internally heated to about 200.degree. C. to boil off the water from the binder, and then to about 750.degree. C.-850.degree. C. to melt the glass frit, while also burning off the organic binder. The melted frit forms a molten glass coating on the metal coil, which is then cooled to solidify the glass, so that the metal coil is covered with a thin continuous homogeneous impervious glass coating of substantially uniform thickness. The glass coating affords complete electrical insulation and complete dielectric protection for the metal coil of the RF antenna, to withstand voltage breakdown and to prevent sputtering, while also doubling the plasma generating efficiency of the RF antenna, when energized with RF power in the vacuum chamber of an ion source for a particle accelerator or the like. The glass frit preferably contains apprxoimately 45% lead oxide.

Ehlers, Kenneth W. (Alamo, CA); Leung, Ka-Ngo (Hercules, CA)

1988-01-01T23:59:59.000Z

95

Radio-frequency plasma transducer for use in harsh environments  

SciTech Connect (OSTI)

We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer, eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0-5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate.

May, Andrew; Andarawis, Emad [GE Global Research, 1 Research Circle, Niskayuna, New York 12309 (United States)

2007-10-15T23:59:59.000Z

96

Radio-frequency plasma transducer for use in harsh environments  

Science Journals Connector (OSTI)

We describe a compact transducer used to generate and modulate low-intensity radio-frequency atmospheric pressure plasma (RF-APP) for high temperature gap measurement and generation of air-coupled ultrasound. The new transducer consists of a quarter-wave transmission line where the ground return path is a coaxial solenoid winding. The RF-APP is initiated at the open end of the transmission line and stabilized by passive negative feedback between the electrical impedance of the plasma and the energy stored in the solenoid. The electrical impedance of the plasma was measured at the lower-voltage source end of the transducer eliminating the need to measure kilovolt-level voltages near the discharge. We describe the use of a 7 MHz RF-APP prototype as a harsh-environment clearance sensor to demonstrate the suitability of plasma discharges for a common nondestructive inspection application. Clearance measurements of 0 – 5 mm were performed on a rotating calibration target with a measurement precision of 0.1 mm and a 20 kHz sampling rate.

Andrew May; Emad Andarawis

2007-01-01T23:59:59.000Z

97

Mapping subsurface fractures by radio-frequency holography: a simulation  

Science Journals Connector (OSTI)

......B. , 1970. Handbook of Electromagnetic...entropy image restoration in astronomy...Aperture and Array System Design, Including...be equal to a power of 2. magnitude...is equal to a power of 2. We assume...B., 1970. Handbook of Electromagnetic...entropy image restoration in astronomy......

Paul Lorrain

1991-08-01T23:59:59.000Z

98

Energy Saving Glass Lamination via Selective Radio-Frequency Heating  

SciTech Connect (OSTI)

This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for potential RF lamination users. A path to industrial energy benefits and revenue through industrial equipment sales was established in a partnership with Thermex Thermatron, a manufacturer of RF equipment.

Shulman, Holly S.; Allan, Shawn M.

2009-11-11T23:59:59.000Z

99

H- radio frequency source development at the Spallation Neutron Source  

SciTech Connect (OSTI)

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

Welton, Robert F [ORNL; Pennisi, Terry R [ORNL; Roseberry, Ron T [ORNL; Stockli, Martin P [ORNL

2012-01-01T23:59:59.000Z

100

Analytical model for the radio-frequency sheath  

Science Journals Connector (OSTI)

A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary symmetry. The externally applied rf voltage is assumed to be sinusoidal, although the model can be extended to arbitrary wave forms, e.g., for dual-frequency discharges. The model calculates explicitly the cubic correction parameter in the charge-voltage relation for the case of highly asymmetric discharges. It is shown that the cubic correction is generally moderate but more pronounced in the collisionless case. The analytical results are compared to experimental data from the literature obtained by laser electric field measurements of the mean and dynamic fields in the capacitive sheath for various gases and pressures. Very good agreement is found throughout.

Uwe Czarnetzki

2013-12-03T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Radio Frequency & Microwave Energy for the Petro Chemical Industry  

E-Print Network [OSTI]

Electro-Magnetic Energy has finally made its way into the Petro-Chemical market twenty-five years after market acceptance in the Food Processing Industry. Major factors influencing this change are tighter environmental regulations, price competition...

Raburn, R.

102

E-Print Network 3.0 - applied radio frequency Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

lines. In addition, we scale our results to the same assumed cosmology and radio frequency (408 MHz... Mon. Not. R. Astron. Soc. (2008) doi:10.1111j.1365-2966.2007.12752....

103

Electrical Features of Radio-frequency, Atmospheric-pressure, Bare-metallic-electrode Glow Discharges  

Science Journals Connector (OSTI)

Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas with bare metallic electrodes have promising prospects in the fields of plasma-aided etching, deposition, disinfection and sterilization, ....

He-Ping Li; Wen-Ting Sun; Hua-Bo Wang; Guo Li…

2007-10-01T23:59:59.000Z

104

Negative ion-containing plasma in parallel-plate radio-frequency discharge in oxygen  

Science Journals Connector (OSTI)

The properties of a plasma in a parallel-plate radio frequency (rf) symmetric discharge of 13.56 MHz in oxygen have been investigated. The plasma contains negative ions. The temperature and density ... .6 eV, dep...

H. Amemiva; N. Yasuda; M. Endou

1994-09-01T23:59:59.000Z

105

Decontamination of VX Surrogate Malathion by Atmospheric Pressure Radio-frequency Plasma Jet  

Science Journals Connector (OSTI)

Decontamination of the VX surrogate (malathion) by the atmospheric pressure radio-frequency plasma jet (APPJ) was investigated. Optical emission ... the neutral gas temperature. The effects of RF input power and ...

Wen-Chao Zhu; Bai-Rong Wang; Hai-Ling Xi…

2010-06-01T23:59:59.000Z

106

Radio-frequency-induced optical gain in Pr3+:Y2SiO5  

Science Journals Connector (OSTI)

We report an observation of radio-frequency (RF)-induced transparency in an optically dense medium of Pr3+-doped Y2SiO5. We observed that the optical...

Ham, B S; Shahriar, M S; Hemmer, P R

1998-01-01T23:59:59.000Z

107

Radio-frequency Ar plasma treatment on muga silk fiber: correlation between physicochemical and surface morphology  

Science Journals Connector (OSTI)

Radio-frequency (RF) Ar plasma treatment is carried out on natural muga silk fibers in a capacitively coupled plasma reactor. The physical and thermal properties of the muga fibers are investigated at an RF power...

Dolly Gogoi; Joyanti Chutia…

2012-11-01T23:59:59.000Z

108

Characteristics of single and dual radio-frequency (RF) plasma sheaths  

Science Journals Connector (OSTI)

The characteristics of radio-frequency (RF) plasma sheaths have been topics of much scientific ... in the study of physical phenomena in dusty plasmas. The sheaths behave special properties under various ... as c...

Zhong-ling Dai; You-nian Wang

2006-06-01T23:59:59.000Z

109

Infrared radio-frequency double resonance of 13CH3OH  

Science Journals Connector (OSTI)

Infrared radio-frequency double-resonance spectroscopy has been carried out for 13CH3OH. Four K-type doublet transitions have been observed below 1 GHz, using the...

Petersen, J C

1987-01-01T23:59:59.000Z

110

Encoding, application and association of radio frequency identification tags on high speed manufacturing lines  

E-Print Network [OSTI]

One of the entry points of radio frequency identification technology in supply chain applications is at the manufacturing line, after production, as packaged goods leave for the next link of the network of suppliers, ...

Fonseca, Herbert Moreti, 1973-

2004-01-01T23:59:59.000Z

111

Integrating Radio Frequency Identification (RFID) data with Electronic Data Interchange (EDI) business processes  

E-Print Network [OSTI]

Radio Frequency Identification (RFID) technology, an important component in the enterprise IT infrastructure, must be integrated into the legacy IT system. This thesis studies how RFID technology can be integrated into the ...

Chen, Yan (Yan Henry), 1976-

2005-01-01T23:59:59.000Z

112

Investigation of inherent radio frequency oscillation and minor switching in amorphous chalcogenide semiconductors  

E-Print Network [OSTI]

INVESTIGATION OF INHERENT RADIO FREQUENCY OSCILLATION AND MINOR SWITCHING IN AMORPHOUS CHALCOGENIDE SEMICONDUCTORS A Thesis by ROBERT WAYNE GILL JR. Submitted to the Graduate College of Texas AAM University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE August 1971 Major Subject: Electrical Engineering INVESTIGATION OF INHERENT RADIO FREQUENCY OSCILLATION AND MINOR SWITCHING IN AMORPHOUS CHALCOGENIDE SEMICONDUCTORS A Thesis by ROBERT WAYNE GILL JR...

Gill, Robert Wayne

1971-01-01T23:59:59.000Z

113

Radio-frequency reflectometry on an undoped AlGaAs/GaAs single electron transistor  

SciTech Connect (OSTI)

Radio frequency reflectometry is demonstrated in a sub-micron undoped AlGaAs/GaAs device. Undoped single electron transistors (SETs) are attractive candidates to study single electron phenomena, due to their charge stability and robust electronic properties after thermal cycling. However, these devices require a large top-gate, which is unsuitable for the fast and sensitive radio frequency reflectometry technique. Here, we demonstrate that rf reflectometry is possible in an undoped SET.

MacLeod, S. J.; See, A. M.; Keane, Z. K.; Scriven, P.; Micolich, A. P.; Hamilton, A. R., E-mail: Alex.Hamilton@unsw.edu.au [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Aagesen, M.; Lindelof, P. E. [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)] [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)

2014-01-06T23:59:59.000Z

114

Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators  

SciTech Connect (OSTI)

The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC. Simulations studies and measurements were conducted that clearly show the correlation between RF noise and longitudinal bunch emittance, identify the major LLRF noise contributions, and determine the RF component dominating this effect. With these results, LHC upgrades and alternative algorithms are evaluated to reduce longitudinal emittance growth during operations. The applications of this work are described with regard to future machines and analysis of new technical implementations, as well as to possible future work which would continue the directions of this dissertation.

Mastoridis, Themistoklis; /Stanford U., Elect. Eng. Dept. /SLAC

2011-03-01T23:59:59.000Z

115

Radio frequency identification enabled wireless sensing for intelligent food logistics  

Science Journals Connector (OSTI)

...semi-passive ultrahigh frequency (UHF) RFID...functionalities, energy source, processing and storage capabilities...backscattering in high frequency (HF) or UHF...changes as a response to the varying...low-cost and energy-efficient under...

2014-01-01T23:59:59.000Z

116

Frequency effects on the electron density and {alpha}-{gamma} mode transition in atmospheric radio frequency discharges  

SciTech Connect (OSTI)

In this paper, a one-dimensional model is explored to investigate the frequency effects on the characteristics of atmospheric radio frequency discharges at a given power. The simulation data and analytical results show that the improvement of electron density can be observed with better discharge stability by increasing excitation frequency in an appropriate range. Using the analytical equations deduced from the model, the mean electron density could be inferred by means of the measured parameters. The {alpha}-{gamma} mode transition especially in high frequency discharges is also analytically discussed based on the theoretical equations.

Zhang Yuantao [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China); Cui Shaoyan [School of Mathematics and Information, Ludong University, Yantai, Shandong Province 264025 (China)

2011-08-15T23:59:59.000Z

117

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect (OSTI)

This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North America. The second task dealt with a study of current lamination processes in the various laminate industries, and development of concepts for integrating RF lamination into new or existing processes. The third task explored the use of a non-destructive technique for analyzing laminate adhesion with the University of Illinois at Urbana-Champaign. The fourth task focused on developing concepts for curved glass lamination using RF lamination. The fifth and sixth tasks together comprised an analysis of laminate product markets, ranking for applicability and commercialization potential, and the development of commercialization strategies for those products. In addition, throughout the project as new experimental data and conventional process data were obtained, the benefits analysis of RF lamination was refined. The goals of the project described above were achieved, positioning RF lamination for the next stage growth envisioned in the original Industrial Grand Challenge proposal. Working with Pilkington North America, lamination of flat autoglass with PVB was achieved, meeting all 16 stringent industry tests. In particular, PVB laminates made with RF lamination passed environmental tests including the high temperature, 120 C bake test, without significant formation of bubbles (defects). The adhesion of PVB to glass was measured using the pummel method. Adhesion values ranging from 1 to 7 out of 10 were obtained. The significant process parameters affecting the environmental and adhesion performance were identified through a designed experiment. Pre-lamination process variables including PVB storage humidity and the de-airing process (vacuum or nip rolling) were significant, as well as the level of pressure applied to the laminate during the RF process. Analysis of manufacturing with RF lamination equipment, based on the processes developed indicated that 3 RF presses could replace a typical auto-industry autoclave to achieve equal or greater throughput with possibly less capital cost and smaller footprint. Concepts for curved lamination identifying castable molds for

Allan, Shawn M.

2012-02-27T23:59:59.000Z

118

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect (OSTI)

This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North America. The second task dealt with a study of current lamination processes in the various laminate industries, and development of concepts for integrating RF lamination into new or existing processes. The third task explored the use of a non-destructive technique for analyzing laminate adhesion with the University of Illinois at Urbana-Champaign. The fourth task focused on developing concepts for curved glass lamination using RF lamination. The fifth and sixth tasks together comprised an analysis of laminate product markets, ranking for applicability and commercialization potential, and the development of commercialization strategies for those products. In addition, throughout the project as new experimental data and conventional process data were obtained, the benefits analysis of RF lamination was refined. The goals of the project described above were achieved, positioning RF lamination for the next stage growth envisioned in the original Industrial Grand Challenge proposal. Working with Pilkington North America, lamination of flat autoglass with PVB was achieved, meeting all 16 stringent industry tests. In particular, PVB laminates made with RF lamination passed environmental tests including the high temperature, 120 ���°C bake test, without significant formation of bubbles (defects). The adhesion of PVB to glass was measured using the pummel method. Adhesion values ranging from 1 to 7 out of 10 were obtained. The significant process parameters affecting the environmental and adhesion performance were identified through a designed experiment. Pre-lamination process variables including PVB storage humidity and the de-airing process (vacuum or nip rolling) were significant, as well as the level of pressure applied to the laminate during the RF process. Analysis of manufacturing with RF lamination equipment, based on the processes developed indicated that 3 RF presses could replace a typical auto-industry autoclave to achieve equal or greater throughput with possibly less capital cost and smaller footprint. Concepts for curved lamination id

Allan, Shawn M.; Baranova, Inessa; Poley, Joseph; Reis, Henrique

2012-02-27T23:59:59.000Z

119

The effect of electromagnetic forces on the penetrator formation during high-frequency electric resistance welding  

Science Journals Connector (OSTI)

During high-frequency electric resistance welding (HF-ERW), the electromagnetic force induced by the high-frequency electric current was studied to improve the understanding of penetrator formation mechanism. ERW melting zone behavior is investigated by the cinematography and the three-dimensional numerical analysis of electromagnetic field around molten metal bridge. Based on the results, the penetrator formation is mainly influenced by the narrow gap shape, the variation of electromagnetic forces along the narrow gap, the molten metal bridge traveling speed, and the second bridge formation frequency. Electromagnetic force acting on the molten metal bridge is rapidly decreasing as the bridge is traveling away from the apex point. The ‘comet’ shape narrow gap produced by the variation of Lorentz forces makes the bridge pushing pressure decrease. Due to the decrease of electromagnetic force and pushing pressure, the sweeping speed of molten metal bridge slows down until the bridge reaches the welding point. Previous molten metal bridge traveling is arrested when the next bridge is formed before the previous bridge arrives at the welding point. Thus, the molten metal and oxide are refilled into the narrow gap due to the capillary force and then remained as a penetrator. According to the analysis of penetrator formation mechanism, the new penetrator formation model is proposed.

Choong-Myeong Kim; Jung-Kyu Kim

2009-01-01T23:59:59.000Z

120

A stable frequency comb directly referenced to rubidium electromagnetically induced transparency and two-photon transitions  

SciTech Connect (OSTI)

We demonstrate an approach to create a stable erbium-fiber-based frequency comb at communication band by directly locking the combs to two rubidium atomic transitions resonances (electromagnetically induced transparency absorption and two-photon absorption), respectively. This approach directly transfers the precision and stability of the atomic transitions to the comb. With its distinguishing feature of compactness by removing the conventional octave-spanning spectrum and f-to-2f beating facilities and the ability to directly control the comb's frequency at the atomic transition frequency, this stable optical comb can be widely used in optical communication, frequency standard, and optical spectroscopy and microscopy.

Hou, Dong; Wu, Jiutao; Zhang, Shuangyou; Ren, Quansheng; Zhang, Zhigang; Zhao, Jianye, E-mail: zhaojianye@pku.edu.cn [Department of Electronics, Peking University, Beijing, 100871 (China)

2014-03-17T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

PARTICLE FILTER BASED MULTI-SENSOR FUSION FOR SOLVING LOW FREQUENCY ELECTROMAGNETIC NDE INVERSE PROBLEMS  

E-Print Network [OSTI]

PARTICLE FILTER BASED MULTI-SENSOR FUSION FOR SOLVING LOW FREQUENCY ELECTROMAGNETIC NDE INVERSE 48824 khantari,sdass@msu.edu, r.pradeep@ieee.org Abstract: Flaw profile characterization from NDE from multi-sensor data is considered. The NDE inverse problem is posed as a statistical inverse problem

Dass, Sarat C.

122

Propagation of Audio-Frequency Radio Waves to Great Distances  

Science Journals Connector (OSTI)

... distances from the source clearly showed that the main concentration of energy lay in the audio-frequency band below 10 kc./s. and that the higher-frequency components moved forward ... selective absorption, which, together with the low attenuation at the extreme ends of the audio-frequency range, accounts for the observed long-distance propagation characteristics of atmospherics1. As is ...

F. W. CHAPMAN; R. C. V. MACARIO

1956-05-19T23:59:59.000Z

123

Preface to Special Topic: Advances in Radio Frequency Physics in Fusion Plasmas  

SciTech Connect (OSTI)

It has long been recognized that auxiliary plasma heating will be required to achieve the high temperature, high density conditions within a magnetically confined plasma in which a fusion “burn” may be sustained by copious fusion reactions. Consequently, the application of radio and microwave frequency electromagnetic waves to magnetically confined plasma, commonly referred to as RF, has been a major part of the program almost since its inception in the 1950s. These RF waves provide heating, current drive, plasma profile control, and Magnetohydrodynamics (MHD) stabilization. Fusion experiments employ electromagnetic radiation in a wide range of frequencies, from tens of MHz to hundreds of GHz. The fusion devices containing the plasma are typically tori, axisymmetric or non, in which the equilibrium magnetic fields are composed of a strong toroidal magnetic field generated by external coils, and a poloidal field created, at least in the symmetric configurations, by currents flowing in the plasma. The waves are excited in the peripheral regions of the plasma, by specially designed launching structures, and subsequently propagate into the core regions, where resonant wave-plasma interactions produce localized heating or other modification of the local equilibrium profiles. Experimental studies coupled with the development of theoretical models and advanced simulation codes over the past 40+ years have led to an unprecedented understanding of the physics of RF heating and current drive in the core of magnetic fusion devices. Nevertheless, there are serious gaps in our knowledge base that continue to have a negative impact on the success of ongoing experiments and that must be resolved as the program progresses to the next generation devices and ultimately to “demo” and “fusion power plant.” A serious gap, at least in the ion cyclotron (IC) range of frequencies and partially in the lower hybrid frequency ranges, is the difficulty in coupling large amount of power to the plasma while minimizing the interaction between the plasma and launching structures. These potentially harmful interactions between the plasma and the vessel and launching structures are challenging: (i) significant and variable loss of power in the edge regions of confined plasmas and surrounding vessel structures adversely affect the core plasma performance and lifetime of a device; (ii) the launcher design is partly “trial and error,” with the consequence that launchers may have to be reconfigured after initial tests in a given device, at an additional cost. Over the broader frequency range, another serious gap is a quantitative lack of understanding of the combined effects of nonlinear wave-plasma processes, energetic particle interactions and non-axisymmetric equilibrium effects on determining the overall efficiency of plasma equilibrium and stability profile control techniques using RF waves. This is complicated by a corresponding lack of predictive understanding of the time evolution of transport and stability processes in fusion plasmas.

Tuccillo, Angelo A.; Ceccuzzi, Silvio [Unità Tecnica Fusione ENEA, C. R. Frascati, 00044 RM (Italy); Phillips, Cynthia K. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2014-06-15T23:59:59.000Z

124

Frequency Shift of Radio Signals in Curved Spacetimes  

E-Print Network [OSTI]

space . . . . . . . . . . . . . . . . . . . . . . . . . . 21 7.2 Schwarzschild space . . . . . . . . . . . . . . . 33 10 Another source of the shift in frequency 34 10.1 Reflection in a relativistically moving mirror

125

UTag: Long-range Ultra-wideband Passive Radio Frequency Tags  

SciTech Connect (OSTI)

Long-range, ultra-wideband (UWB), passive radio frequency (RF) tags are key components in Radio Frequency IDentification (RFID) system that will revolutionize inventory control and tracking applications. Unlike conventional, battery-operated (active) RFID tags, LLNL's small UWB tags, called 'UTag', operate at long range (up to 20 meters) in harsh, cluttered environments. Because they are battery-less (that is, passive), they have practically infinite lifetimes without human intervention, and they are lower in cost to manufacture and maintain than active RFID tags. These robust, energy-efficient passive tags are remotely powered by UWB radio signals, which are much more difficult to detect, intercept, and jam than conventional narrowband frequencies. The features of long range, battery-less, and low cost give UTag significant advantage over other existing RFID tags.

Dowla, F

2007-03-14T23:59:59.000Z

126

Resistance Compression Networks for Radio-Frequency Power Conversion  

E-Print Network [OSTI]

A limitation of many high-frequency resonant inverter topologies is their high sensitivity to loading conditions. This paper introduces a new class of matching networks that greatly reduces the load sensitivity of resonant ...

Han, Yehui

127

Radio-Frequency Inverters With Transmission-Line Input Networks  

E-Print Network [OSTI]

A soft-switching inverter topology (the Class Phi ) is presented which draws dc source current through a transmission line or a lumped-network approximation of a distributed line. By aligning the inverter switching frequency ...

Phinney, Joshua W.

128

Propagation of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency  

SciTech Connect (OSTI)

In this paper, we investigate the absorption spectra of terahertz electromagnetic wave in plasma with inhomogeneous collision frequency. Profiles are introduced to describe the non-uniformity of collision frequency. It is interesting to find that when the plasma is collision frequency inhomogeneous, the absorption spectrum would decreases faster than that in uniform plasma. And the rate of decreasing would be different when the profile changes. Two parameters are set up to predict how the profiles affect the absorption spectra. Furthermore, the effects of electron density are also considered.

Tian, Yuan; Han, YiPing; Ling, YingJie [School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071 (China)] [School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071 (China); Ai, Xia [National Laboratory of Science and Technology on Antennas and Microwaves Xidian University, Xi'an 710071 (China)] [National Laboratory of Science and Technology on Antennas and Microwaves Xidian University, Xi'an 710071 (China)

2014-02-15T23:59:59.000Z

129

Characteristics of radio-frequency, atmospheric-pressure glow discharges with air using bare metal electrodes  

SciTech Connect (OSTI)

In this letter, an induced gas discharge approach is proposed and described in detail for obtaining a uniform atmospheric-pressure glow discharge with air in a {gamma} mode using water-cooled, bare metal electrodes driven by radio-frequency (13.56 MHz) power supply. A preliminary study on the discharge characteristics of the air glow discharge is also presented in this study. With this induced gas discharge approach, radio-frequency, atmospheric-pressure glow discharges using bare metal electrodes with other gases which cannot be ignited directly as the plasma working gas, such as nitrogen, oxygen, etc., can also be obtained.

Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Zhang Xiaozhang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2006-10-16T23:59:59.000Z

130

Single shot time stamping of ultrabright radio frequency compressed electron pulses  

SciTech Connect (OSTI)

We demonstrate a method of time-stamping Radio Frequency compressed electron bunches for Ultrafast Electron Diffraction experiments in the sub-pC regime. We use an in-situ ultra-stable photo-triggered streak camera to directly track the time of arrival of each electron pulse and correct for the timing jitter in the radio frequency synchronization. We show that we can correct for timing jitter down to 30 fs root-mean-square with minimal distortion to the diffraction patterns, and performed a proof-of-principle experiment by measuring the ultrafast electron-phonon coupling dynamics of silicon.

Gao, M.; Dwayne Miller, R. J. [Department of Chemistry and Physics, University of Toronto, Toronto, ON. M5S 3H6 (Canada); Max Planck Research Department for Structural Dynamics, Department of Physics, Center for Free Electron Laser Science, University of Hamburg, DESY, D-22607 Hamburg (Germany); Jiang, Y.; Kassier, G. H. [Max Planck Research Department for Structural Dynamics, Department of Physics, Center for Free Electron Laser Science, University of Hamburg, DESY, D-22607 Hamburg (Germany)

2013-07-15T23:59:59.000Z

131

Magnetic field probes for use in radio frequency plasma  

SciTech Connect (OSTI)

An impedance analyzer has been used in the characterization of a magnetic induction probe (B-dot probe) for use in plasma. The role of the impedance analyzer was to determine the frequency response of a B-dot probe up to 100 MHz. The probe was specifically designed to take measurements in rf plasma driven at 13.56 MHz. Probe sensitivity and calibration are considered based on the impedance values obtained when a B-dot probe is swept over a wide frequency range. Effects such as unbalanced loads based on transmission line inductances and termination impedance are shown to be limiting factors on the probes useful frequency range. The use of an impedance analyzer allows these effects to readily be characterized.

Reilly, Michael P.; Miley, George H. [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, 104 S. Wright Street, 216 Talbot Laboratory, MC-234 Urbana, Illinois 61801 (United States); Lewis, William [ERC Inc. Knight High School, 37423 70th Street East, Palmdale, California 93552 (United States)

2009-05-15T23:59:59.000Z

132

High-rate chemical vapor deposition of nanocrystalline silicon carbide films by radio frequency thermal plasma  

E-Print Network [OSTI]

High-rate chemical vapor deposition of nanocrystalline silicon carbide films by radio frequency Semiconductor, Eden Prairie, MN, USA Received 10 July 2002; accepted 14 July 2002 Abstract Silicon carbide films; Nanomaterials; Silicon carbide; Thermal plasmas; Thin films; Si tetrachlorine precursor Silicon carbide has

Zachariah, Michael R.

133

Stochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a)  

E-Print Network [OSTI]

Stochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a) V. I. Kolobov Received 2 November 1995; accepted for publication 7 October 1996 The mechanisms of electron heating in low for the stochastic heating. A classification of heating regimes is performed and expressions for the power deposition

Kaganovich, Igor

134

A high-performance cryogenic amplifier based on a radio-frequency single electron transistor  

E-Print Network [OSTI]

A high-performance cryogenic amplifier based on a radio-frequency single electron transistor K, Sweden Received 23 May 2002; accepted 24 October 2002 We demonstrate a high-performance cryogenic-chip integrability, make it a good candidate for a general-purpose cryogenic amplifier for high impedance sources. We

Segall, Ken

135

Radio-Frequency Current Drive in a Fusion-Producing Plasma  

Science Journals Connector (OSTI)

A method for driving current in a fusion-producing plasma is proposed. Radio-frequency power is used to prohibit fusion-produced energetic particles from slowing down isotropically or to push them in a preferential direction. As a result, a net plasma current is generated whose efficiency is comparable to other current drive schemes.

D. K. Bhadra and C. Chu

1982-06-28T23:59:59.000Z

136

Radio Frequency Id and Privacy with Information Goods Nathan Gooda1  

E-Print Network [OSTI]

of Computing] General Terms Security, Legal Aspects. Keywords RFID, privacy, information goods, law, policy. 1. NORMS AND LAW This paper examines the privacy impacts of using radio frequency identification (RFID privacy. Put simply, in the RFID-enabled world, anyone with an RFID reader can potentially discover

Wagner, David

137

Radio frequency regenerative oscillations in monolithic high-Q/V heterostructured photonic crystal cavities  

E-Print Network [OSTI]

of the radio frequency tones by laser-cavity detuning and laser power levels, confirmed by the CMT simulations crystal cavity is removed by buffered oxide wet etching. Inverse tapered couplers with an oxide over-cladding the CW coherent transverse-electric light from a tunable laser onto chip through polarization control

Hone, James

138

Using Multiple Beams to Distinguish Radio Frequency Interference from SETI Signals  

E-Print Network [OSTI]

Using Multiple Beams to Distinguish Radio Frequency Interference from SETI Signals G. R. Harp Allen for extra-terrestrial intelligence) observations. It is a multi-beam instrument, with 16 independently steerable dual- polarization beams at 4 different tunings. Given 4 beams at one tuning, it is possible

Ellingson, Steven W.

139

Plasma acceleration from radio-frequency discharge in dielectric capillary A. Dunaevskya  

E-Print Network [OSTI]

Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 Received 19 August 2005; accepted 22Plasma acceleration from radio-frequency discharge in dielectric capillary A. Dunaevskya Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 Y. Raitses and N. J. Fisch Princeton

140

Coupling effects in inductive discharges with radio frequency substrate biasing  

SciTech Connect (OSTI)

Low pressure inductively coupled plasmas (ICP) operated in neon at 27.12 MHz with capacitive substrate biasing (CCP) at 13.56 MHz are investigated by phase resolved optical emission spectroscopy, voltage, and current measurements. Three coupling mechanisms are found potentially limiting the separate control of ion energy and flux: (i) Sheath heating due to the substrate biasing affects the electron dynamics even at high ratios of ICP to CCP power. At fixed CCP power, (ii) the substrate sheath voltage and (iii) the amplitude as well as frequency of plasma series resonance oscillations of the RF current are affected by the ICP power.

Schulze, J.; Schuengel, E.; Czarnetzki, U.

2012-01-09T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Radio-frequency stabilization of a nonequilibrium plasma accelerator  

SciTech Connect (OSTI)

Results of experimental studies of the effect of an external RF field on the excitation of oscillations in a magnetoplasmadynamic plasma accelerator are presented. It is found that applying an RF field can suppress the drift component of low-frequency oscillations in the ejected plasma flow. The experimental data agree with the concept of stabilization of the plasma accelerator by the magnetic component of the field generated by the RF current loop. The conditions under which the RF field stabilizes the generation of the plasma flow are determined, and the factors limiting the stabilization efficiency are revealed.

Kirdyashev, K. P. [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Fryazino Branch) (Russian Federation)

2011-08-15T23:59:59.000Z

142

Fourier synthesis and timbre tuning of radio frequency nanomechanical pulses  

E-Print Network [OSTI]

The concept of Fourier synthesis provides the foundation for both everyday consumer electronic products and fundamental research. In the latter, so called pulse shaping is nowadays key to dynamically initialize, probe and manipulate the state of classical or quantum systems. In nuclear magnetic resonance, for instance, shaped pulses have a long-standing tradition and the underlying fundamental concepts have subsequently been successfully extended to optical frequencies and even to implement quantum gate operations. Transfer of these paradigms to nanomechanical systems, requires tailored nanomechanical waveforms (NMWFs) for mechanically mediated coherent control schemes. Here, we report on a novel additive Fourier synthesizer for NMWFs based on monochromatic surface acoustic waves (SAWs). As a proof of concept, we electrically synthesize four different elementary NMWFs from a fundamental SAW at $ f_1 \\sim 150$ MHz using a superposition of up to three discrete harmonics $f_n$. We employ these shaped pulses to i...

Schülein, Florian J R; Atkinson, Paola; Schmidt, Oliver G; Trotta, Rinaldo; Rastelli, Armando; Wixforth, Achim; Krenner, Hubert J

2014-01-01T23:59:59.000Z

143

Discharge ignition characteristics of pulsed radio-frequency glow discharges in atmospheric helium  

Science Journals Connector (OSTI)

An experimental study of radio-frequency (15 MHz) glow discharges in atmospheric helium modulated by pulses with repetition frequency of 500 kHz and duty cycle of 6% and 8% is presented in this paper. In each discharge burst the discharge is restricted to operate in ignition phase with duration of one or two radio-frequency cycles. The ignition characteristics in terms of spatial-temporal evolution of discharge interelectrode structure and optical emission intensity are investigated by time resolved imaging. Optical emission intensities at lines of 706 and 777 nm are used to capture clearly the temporal evolution of energetic electrons and active specie of atom oxygen generated in discharge.

Jianjun Shi; Yeqing Cai; Jie Zhang; Ke Ding; Jing Zhang

2009-01-01T23:59:59.000Z

144

Discharge ignition characteristics of pulsed radio-frequency glow discharges in atmospheric helium  

SciTech Connect (OSTI)

An experimental study of radio-frequency (15 MHz) glow discharges in atmospheric helium modulated by pulses with repetition frequency of 500 kHz and duty cycle of 6% and 8% is presented in this paper. In each discharge burst, the discharge is restricted to operate in ignition phase with duration of one or two radio-frequency cycles. The ignition characteristics in terms of spatial-temporal evolution of discharge interelectrode structure and optical emission intensity are investigated by time resolved imaging. Optical emission intensities at lines of 706 and 777 nm are used to capture clearly the temporal evolution of energetic electrons and active specie of atom oxygen generated in discharge.

Shi Jianjun; Cai Yeqing; Zhang Jie; Ding Ke; Zhang Jing [State Key Lab for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, and College of Science, Donghua University, Shanghai 201620 (China)

2009-07-15T23:59:59.000Z

145

Frequency effects on the production of reactive oxygen species in atmospheric radio frequency helium-oxygen discharges  

SciTech Connect (OSTI)

Several experimental and computational studies have shown that increasing frequency can effectively enhance the discharge stability in atmospheric radio-frequency (rf) discharges, but the frequency effects on the reactivity of rf discharges, represented by the densities of reactive oxygen species (ROS), are still far from fully understood. In this paper, a one-dimensional fluid model with 17 species and 65 reactions taken into account is used to explore the influences of the driving frequency on the production and destruction of ROS in atmospheric rf helium-oxygen discharges. From the computational results, with an increase in the frequency the densities of ROS decrease always at a constant power density, however, in the relatively higher frequency discharges the densities of ROS can be effectively improved by increasing the input power density with an expanded oxygen admixture range, while the discharges operate in the {alpha} mode, and the numerical data also show the optimal oxygen admixture for ground state atomic oxygen, at which the peak atomic oxygen density can be obtained, increases with the driving frequency.

Zhang, Yuantao T.; He Jin [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China)

2013-01-15T23:59:59.000Z

146

A narrow window of Rabi frequency for competition between electromagnetically induced transparency and Raman absorption  

SciTech Connect (OSTI)

This investigation clarifies the transition phenomenon between the electromagnetically induced transparency (EIT) and Raman absorption in a ladder-type system of Doppler-broadened cesium vapor. A competition window of this transition was found to be as narrow as 2 MHz defined by the probe Rabi frequency. For a weak probe, the spectrum of EIT associated with quantum interference suggests that the effect of the Doppler velocity on the spectrum is negligible. When the Rabi frequency of the probe becomes comparable with the effective decay rate, an electromagnetically induced absorption (EIA) dip emerges at the center of the power broadened EIT peak. While the Rabi frequency of the probe exceeds the effective decay rate, decoherence that is generated by the intensified probe field occurs and Raman absorption dominates the interaction process, yielding a pure absorption spectrum; the Doppler velocity plays an important role in the interaction. A theory that is based on density matrix simulation, with or without the Doppler effect, can qualitatively fit the experimental data. In this work, the coherence of atom-photon interactions is created or destroyed using the probe Rabi frequency as a decoherence source.

Chang, Ray-Yuan; Fang, Wei-Chia; Lee, Ming-Tsung; He, Zong-Syun; Ke, Bai-Cian [Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan (China); Lee, Yi-Chi [Institute of Electro-Optical Science and Engineering, National Cheng-Kung University, Tainan 70101, Taiwan (China); Tsai, Chin-Chun [Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan (China); Institute of Electro-Optical Science and Engineering, National Cheng-Kung University, Tainan 70101, Taiwan (China)

2010-01-15T23:59:59.000Z

147

Calcium homeostasis of isolated heart muscle cells exposed to pulsed high-frequency electromagnetic fields  

SciTech Connect (OSTI)

The intracellular calcium concentration ([Ca{sup 2+}]{sub i}) of isolated ventricular cardiac myocytes of the guinea pig was measured during the application of pulsed high-frequency electromagnetic fields. The high-frequency fields were applied in a transverse electromagnetic cell designed to allow microscopic observation of the myocytes during the presence of the high-frequency fields. The [Ca{sup 2+}]{sub i} was measured as fura-2 fluorescence by means of digital image analysis. Both the carrier frequency and the square-wave pulse-modulation pattern were varied during the experiments (carrier frequencies: 900, 1,300, and 1,800 MHz pulse modulated at 217 Hz with 14% duty cycle; pulsation pattern at 900 MHz; continuous wave, 16 Hz,and 50 Hz modulation with 50% duty cycle and 30 kHz modulation with 80% duty cycle). The mean specific absorption rate (SAR) values in the solution were within one order of magnitude of 1 mW/kg. They varied depending on the applied carrier frequency and pulse pattern. The experiments were designed in three phases: 500 s of sham exposure, followed by 500 s of field exposure, then chemical stimulation without field. The chemical stimulation (K{sup +}-depolarization) indicated the viability of the cells. The K{sup +} depolarization yielded a significant increase in [Ca{sup 2+}]{sub i}. Significant differences between sham exposure and high-frequency field exposure were not found except when a very small but statistically significant difference was detected in the case of 900 MHz/50 Hz. However, this small difference was not regarded as a relevant effect of the exposure.

Wolke, S.; Gollnick, F.; Meyer, R. [Univ. Bonn (Germany)] [Univ. Bonn (Germany); Neibig, U.; Elsner, R. [Inst. fuer Nachrichtentechnik Braunschweig (Germany)] [Inst. fuer Nachrichtentechnik Braunschweig (Germany)

1996-05-01T23:59:59.000Z

148

Discharge characteristics of atmospheric-pressure radio-frequency glow discharges with argon/nitrogen  

SciTech Connect (OSTI)

In this letter, atmospheric-pressure glow discharges in {gamma} mode with argon/nitrogen as the plasma-forming gas using water-cooled, bare copper electrodes driven by radio-frequency power supply at 13.56 MHz are achieved. The preliminary studies on the discharge characteristics show that, induced by the {alpha}-{gamma} coexisting mode or {gamma} mode discharge of argon, argon-nitrogen mixture with any mixing ratios, even pure nitrogen, can be employed to generate the stable {gamma} mode radio-frequency, atmospheric-pressure glow discharges and the discharge voltage rises with increasing the fraction of nitrogen in the argon-nitrogen mixture for a constant total gas flow rate.

Wang Huabo; Sun Wenting; Li Heping; Bao Chengyu; Gao Xing; Luo Huiying [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); School of Public Health and Family Medicine, Capital University of Medical Sciences, Beijing 100069 (China); Beijing Center for Diseases Control and Prevention, Beijing 100013 (China)

2006-10-16T23:59:59.000Z

149

Scattering of Radio Frequency Waves by Edge Density Blobs in Tokamak Plasmas  

SciTech Connect (OSTI)

The density blobs and fluctuations present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction and diffraction. The scattering can diffuse the rays in space and in wave-vector space. The diffusion in space can make the rays miss their intended target region, while the diffusion in wave-vector space can broaden the wave spectrum and modify the wave damping and current profile.

Ram, A. K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hizanidis, K.; Kominis, Y. [National Technical University of Athens, Association EURATOM-Hellenic Republic, Zografou, Athens 15773 (Greece)

2011-12-23T23:59:59.000Z

150

Evolution of a Dust Void in a Radio-Frequency Plasma Sheath  

Science Journals Connector (OSTI)

The onset and growth of a dust void are investigated in a radio-frequency (rf) sheath of a capacitively coupled argon plasma. A circularly symmetric void emerges and grows with increasing rf power and pressure in the central region of the dust cloud levitating in the sheath. Experimental measurements of the void diameter are compared with the predictions of a simple phenomenological theory, based on a balance of forces on dust grains.

R. P. Dahiya; G. V. Paeva; W. W. Stoffels; E. Stoffels; G. M. W. Kroesen; K. Avinash; A. Bhattacharjee

2002-08-27T23:59:59.000Z

151

CW 100 kW radio frequency-free-electron laser design at 10. mu. m  

SciTech Connect (OSTI)

This paper describes the 100 kW CW radio frequency-free-electron last at 10{mu}m to be built at Boeing Defense and Space Group in collaboration with Los Alamos National Laboratory. The authors discuss the criteria which led to the selection of the operating point, the single-accelerator master-oscillator and power-amplifier configuration, the goals of this experiment, and the expected performance.

Parazzoli, C.G.; Rodenburg, R.E.; Romero, J.B.; Adamski, J.L.; Pistoresi, D.J.; Shoffstall, D.R. (Boeing Defense and Space Group, Seattle, WA (US)); Quimby, D.C. (STI Optronics, Inc., Bellevue, WA (US))

1991-12-01T23:59:59.000Z

152

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

SciTech Connect (OSTI)

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

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

2012-07-15T23:59:59.000Z

153

Modes in a pulse-modulated radio-frequency dielectric-barrier glow discharge  

SciTech Connect (OSTI)

This letter reports an experimental study of a pulse-modulated radio-frequency dielectric-barrier discharge in atmospheric helium. By controlling the duty cycle at a modulation frequency of 10 and 100 kHz, the 13.56 MHz discharge is shown to operate in three different glow modes: the continuum mode, the discrete mode, and the transition mode. By investigating plasma ignition, residual electrons during power off are found to affect different glow modes. Duty cycle dependences of power density, gas temperature, optical emission intensities at 706 and 777 nm are used to capture clearly the characteristics of the three glow modes.

Shi, J. J.; Zhang, J.; Qiu, G. [College of Science, Donghua University, Shanghai 201620 (China); Walsh, J. L.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

2008-07-28T23:59:59.000Z

154

Modes in a pulse-modulated radio-frequency dielectric-barrier glow discharge  

Science Journals Connector (OSTI)

This letter reports an experimental study of a pulse-modulated radio-frequency dielectric-barrier discharge in atmospheric helium. By controlling the duty cycle at a modulation frequency of 10 and 100 kHz the 13.56 MHz discharge is shown to operate in three different glow modes: the continuum mode the discrete mode and the transition mode. By investigating plasma ignition residual electrons during power off are found to affect different glow modes. Duty cycle dependences of power density gas temperature optical emission intensities at 706 and 777 nm are used to capture clearly the characteristics of the three glow modes.

J. J. Shi; J. Zhang; G. Qiu; J. L. Walsh; M. G. Kong

2008-01-01T23:59:59.000Z

155

Measurements and modeling of radio frequency field structures in a helicon plasma  

SciTech Connect (OSTI)

Measurements of the radio frequency (rf) field structure, plasma density, and electron temperature are presented for a 1 kW argon helicon plasma source. The measured profiles change considerably when the equilibrium magnetic field is reversed. The measured rf fields are identified as fields of radially localized helicon waves, which propagate in the axial direction. The rf field structure is compared to the results of two-dimensional cold plasma full-wave simulations for the measured density profiles. Electron collision frequency is adjusted in the simulations to match the simulated and measured field profiles. The resulting frequency is anomalously high, which is attributed to the excitation of an ion-acoustic instability. The calculated power deposition is insensitive to the collision frequency and accounts for most of the power supplied by the rf-generator.

Lee, C. A. [University of Texas, Austin; Chen, Guangye [ORNL; Arefiev, A. V. [University of Texas, Austin; Bengtson, R. D. [University of Texas, Austin; Breizman, B. N. [University of Texas, Austin

2011-01-01T23:59:59.000Z

156

Frequency dependence of microparticle charge in a radio frequency discharge with Margenau electron velocity distribution  

SciTech Connect (OSTI)

rf discharges are widely used in complex plasma experiments. In this paper, we theoretically investigate the dependence of the particle floating potential on the discharge frequency, assuming the model Margenau expression for the electron velocity distribution function. In doing so we use the orbital motion limited cross section to calculate the electron flux to the particle and collision enhanced collection approximation for the ion flux to the particle. The floating potential is then obtained from the flux balance condition. It is shown that for typical plasma conditions in laboratory rf discharges, normalized floating potential grows with increase of the discharge frequency in collisionless regime and decreases in weakly collisional regime. However, variations in the floating potential are usually small when plasma parameters do not depend on the rf frequency.

Du, Cheng-Ran; Khrapak, Sergey A.; Antonova, Tetyana; Steffes, Bernd; Thomas, Hubertus M.; Morfill, Gregor E. [Max Plank Institute for Extraterrestrial Physics, Garching 85741 (Germany)

2011-01-15T23:59:59.000Z

157

First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype  

E-Print Network [OSTI]

We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array, observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9–201.6 MHz. ...

Oberoi, Divya

158

Studies on the Matching Network of the High Power Radio Frequency Transmitter for the NBI RF Ion Source  

Science Journals Connector (OSTI)

A radio frequency (RF) driven ion source has been developed at ASIPP (Institute of Plasma Physics, CAS) for the neutral beam injector with a 1 MHz, 25 kW RF power supply system. The paper describes the studies pe...

Renxue Su; Zhimin Liu; Yahong Xie; Yuqian Chen; Yuming Gu…

2014-08-01T23:59:59.000Z

159

High rate deposition of microcrystalline silicon films by high-pressure radio frequency plasma enhanced chemical vapor deposition (PECVD)  

Science Journals Connector (OSTI)

Hydrogenated microcrystalline silicon (?c-Si:H) thin films were prepared by high-pressure radio-frequency (13.56 MHz) plasma enhanced chemical vapor deposition (rf-PECVD) with a screened plasma. The deposition ra...

BingQing Zhou; MeiFang Zhu; FengZhen Liu…

2008-04-01T23:59:59.000Z

160

Time?differential radio?frequency muon spin resonance (TD?RF?SR) technique at a pulsed muon beam  

Science Journals Connector (OSTI)

Longitudinal?field ?SR methods, e.g., radio?frequency ?+...spin resonance (RF?SR), are well suited to investigate dynamic processes that destroy the phase coherence of the muon spin ensemble. Additional informati...

R. Scheuermann; J. Schmidl; A. Seeger; Th. Stammler; D. Herlach…

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Engineering Sciences 151 Electromagnetic Communication  

E-Print Network [OSTI]

Engineering Sciences 151 Electromagnetic Communication Laboratory Assignment 1 Fall Term 1998, Audio frequency spectrum analyzer Tektronix, Model 2230, 100MHz Dual-channel storage oscilloscope generator Hewlett-Packard, Model 200CD, Wide range audio oscillator General Radio, Model 1398-A, Pulse

Jones, R. Victor

162

Investigation of effect of excitation frequency on electron energy distribution functions in low pressure radio frequency bounded plasmas  

SciTech Connect (OSTI)

Particle in cell (PIC) simulations are employed to investigate the effect of excitation frequency {omega} on electron energy distribution functions (EEDFs) in a low pressure radio frequency (rf) discharge. The discharge is maintained over a length of 0.10 m, bounded by two infinite parallel plates, with the coherent heating field localized at the center of the discharge over a distance of 0.05 m and applied perpendicularly along the y and z directions. On varying the excitation frequency f (={omega}/2{pi}) in the range 0.01-50 MHz, it is observed that for f {<=} 5 MHz the EEDF shows a trend toward a convex (Druyvesteyn-like) distribution. For f > 5 MHz, the distribution resembles more like a Maxwellian with the familiar break energy visible in most of the distributions. A prominent ''hot tail'' is observed at f{>=} 20 MHz and the temperature of the tail is seen to decrease with further increase in frequency (e.g., at 30 MHz and 50 MHz). The mechanism for the generation of the ''hot tail'' is considered to be due to preferential transit time heating of energetic electrons as a function of {omega}, in the antenna heating field. There exists an optimum frequency for which high energy electrons are maximally heated. The occurrence of the Druyvesteyn-like distributions at lower {omega} may be explained by a balance between the heating of the electrons in the effective electric field and elastic cooling due to electron neutral collision frequency {nu}{sub en}; the transition being dictated by {omega} {approx} 2{pi}{nu}{sub en}.

Bhattacharjee, Sudeep [Space plasma, Power and Propulsion, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Department of Physics, Indian Institute of Technology, Kanpur 208 016 (India); Lafleur, Trevor; Charles, Christine; Boswell, Rod [Space plasma, Power and Propulsion, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2011-07-15T23:59:59.000Z

163

Determination of High-Frequency Current Distribution Using EMTP-Based Transmission Line Models with Resulting Radiated Electromagnetic Fields  

SciTech Connect (OSTI)

Application of BPL technologies to existing overhead high-voltage power lines would benefit greatly from improved simulation tools capable of predicting performance - such as the electromagnetic fields radiated from such lines. Existing EMTP-based frequency-dependent line models are attractive since their parameters are derived from physical design dimensions which are easily obtained. However, to calculate the radiated electromagnetic fields, detailed current distributions need to be determined. This paper presents a method of using EMTP line models to determine the current distribution on the lines, as well as a technique for using these current distributions to determine the radiated electromagnetic fields.

Mork, B; Nelson, R; Kirkendall, B; Stenvig, N

2009-11-30T23:59:59.000Z

164

The recovery of glow-plasma structure in atmospheric radio frequency microplasmas at very small gaps  

Science Journals Connector (OSTI)

In atmospheric radio frequency discharges at 13.56 MHz with the electrode gap reduced the sheath region eventually occupies a main portion of the electrode spacing and the bulk plasma region is significantly compressed. The computational results in this letter based on a one-dimensional fluid model show that by increasing the excitation frequency over 13.56 MHz the traditional glow-plasma structure could gradually recover even at very small sizes with a well defined quasineutral plasma region and the electron density is improved but the electric fields in sheath region are reduced. This study indicates that the excitation frequency can be used to modulate the discharge structure and then tailor the plasma-surface interaction in atmospheric microplasmas.

Yuan-Tao Zhang; Wan-Li Shang

2011-01-01T23:59:59.000Z

165

The recovery of glow-plasma structure in atmospheric radio frequency microplasmas at very small gaps  

SciTech Connect (OSTI)

In atmospheric radio frequency discharges at 13.56 MHz, with the electrode gap reduced, the sheath region eventually occupies a main portion of the electrode spacing and the bulk plasma region is significantly compressed. The computational results in this letter based on a one-dimensional fluid model show that by increasing the excitation frequency over 13.56 MHz, the traditional glow-plasma structure could gradually recover even at very small sizes with a well defined quasineutral plasma region, and the electron density is improved but the electric fields in sheath region are reduced. This study indicates that the excitation frequency can be used to modulate the discharge structure and then tailor the plasma-surface interaction in atmospheric microplasmas.

Zhang Yuantao [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan 250061, Shandong Province (China); Shang Wanli [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, Sichuan Province (China)

2011-11-15T23:59:59.000Z

166

The JT-60 radio-frequency heating system: description and R&D results  

Science Journals Connector (OSTI)

A system feature of the radio-frequency (RF) heating system for JT-60 is described. This system contains three units Lower Hybrid Range of Frequencies (LHRF) and one unit Ion Cyclotron Range of Frequencies (ICRF) heating systems. The LHRF heating system produces about 24 MW at 2 \\{GHz\\} of RF power using 24 high power klystrons and the ICRF heating system does 6 MW at 120 \\{MHz\\} of RF power using 8 high power tetrodes. Development of a high power klystron for the LHRF heating system and the coupling system for high power density of the transmission are performed for the construction of the RF heating system for JT-60. Japan Atomic Energy Research Institute (JAERI) has already constructed the RF heating system for JT-60 and is now performing the coupling test to JT-60 plasma.

T. Nagashima; K. Uehara; H. Kimura; T. Imai; T. Fujii; K. Sakamoto; Y. Ikeda; M. Saigusa; N. Suzuki; M. Honda; K. Yokokura; K. Kiyono; M. Sawahata; K. Suganuma; M. Seki; H. Shirakata

1987-01-01T23:59:59.000Z

167

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode  

SciTech Connect (OSTI)

A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies - 500 kHz to 30 MHz, and rf bias waveforms - sinusoidal, square, and dual frequency.

Gahan, D.; Hopkins, M. B. [National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland); Dolinaj, B. [Impedans Ltd., Invent Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2008-03-15T23:59:59.000Z

168

MULTI-FREQUENCY STUDIES OF RADIO RELICS IN THE GALAXY CLUSTERS A4038, A1664, AND A786  

SciTech Connect (OSTI)

We present a multi-frequency study of radio relics associated with the galaxy clusters A4038, A1664, and A786. Radio images, integrated spectra, spectral index maps, and fits to the integrated spectra in the framework of the adiabatic compression model are presented. Images of the relic in A4038 at 150, 240, and 606 MHz with the Giant Meterwave Radio Telescope have revealed extended ultra-steep spectrum ({alpha} {approx} -1.8 to -2.7) emission of extent 210 Multiplication-Sign 80 kpc{sup 2}. The model of passively evolving radio lobes compressed by a shock fits the integrated spectrum best. The relic with a circular morphology at the outskirts of the cluster A1664 has an integrated spectral index of {approx} - 1.10 {+-} 0.06 and is best fit by the model of radio lobes lurking for {approx}4 Multiplication-Sign 10{sup 7} yr. The relic near A786 has a curved spectrum and is best fit by a model of radio lobes lurking for {approx}3 Multiplication-Sign 10{sup 7} yr. At 4.7 GHz, a compact radio source, possibly the progenitor of the A786 relic, is detected near the center of the radio relic. The A786 radio relic is thus likely a lurking radio galaxy rather than a site of cosmological shock as has been considered in earlier studies.

Kale, Ruta; Dwarakanath, K. S., E-mail: ruta@iucaa.ernet.in [Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080 (India)

2012-01-01T23:59:59.000Z

169

Improvement of isentropic efficiency of a magnetohydrodynamic power generator by radio-frequency preionization  

Science Journals Connector (OSTI)

We describe the effect of a radio-frequency (rf) power application on the performance of a magnetohydrodynamic(MHD) electrical power generator as determined through shock-tunnel-based experiments and quasi-three-dimensional numerical simulations. The temporal plasma-fluid behavior the one-dimensional plasma-fluid structure the enthalpy-entropy diagram the quality of the energy conversion efficiency and the energy flow in the power-generating system are investigated. Preionization assistance by a small amount of rf power drastically changes the entire MHD power-generating system; the MHD extraction length is considerably extended and the isentropic efficiency is significantly improved.

Tomoyuki Murakami; Yoshihiro Okuno

2009-01-01T23:59:59.000Z

170

Numerical modeling of dust particle configurations in a cylindrical radio-frequency plasma reactor  

Science Journals Connector (OSTI)

In the present work, first, plasma phase variables in a cylindrical radio-frequency (rf) plasma reactor are numerically solved using the local field approximation model. Then, equilibrium configurations of a few interacting (sub-)micron-sized dust particles are obtained by integrating the particles equations for their motion and charge, accounting for the various forces acting on each particle in a three-dimensional Lagrangian framework. Direct comparison of the results with experiment demonstrates excellent qualitative agreement. Based on the ion focus phenomenon, a physical model is formulated and proven successful in simulating the vertically aligned structures.

M. Davoudabadi and F. Mashayek

2007-11-30T23:59:59.000Z

171

Study of the change of electron temperature inside magnetic island caused by localized radio frequency heating  

SciTech Connect (OSTI)

The change in the electron temperature inside magnetic island caused by localized radio frequency (rf) heating is studied numerically by solving the two-dimensional energy transport equation, to investigate the dependence of the temperature change on the location and width of the rf power deposition along the minor radius and the helical angle, the island width, and the ratio between the parallel and the perpendicular heat conductivity. Based on obtained numerical results, suggestions for optimizing the island stabilization by localized rf heating are made.

Yang, J.; Zhu, S. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031 (China); Yu, Q. [Max-Planck-Institute fuer Plasmaphysik, EURATOM Association, Garching 85748 (Germany); Zhuang, G. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-05-15T23:59:59.000Z

172

Evolution of Discharge Structure in Capacitive Radio-Frequency Atmospheric Microplasmas  

Science Journals Connector (OSTI)

Conventional radio-frequency (rf) nonthermal atmospheric plasmas are generated in a millimeter gap. In this Letter, we present a self-consistent numerical study of rf atmospheric microplasmas in a submillimeter gap comparable to their sheath thickness. It is shown that the narrow electrode gap deforms the discharge structure, ultimately removing the bulk-plasma region and disabling electron trapping. Significantly, these properties permit rf atmospheric microplasmas to operate at very high current densities thus simultaneously achieving higher stability and greater chemical reactivity.

J. J. Shi and M. G. Kong

2006-03-16T23:59:59.000Z

173

Tuning the work function of graphene by nitrogen plasma treatment with different radio-frequency powers  

SciTech Connect (OSTI)

Graphene prepared by the chemical vapor deposition method was treated with nitrogen plasma under different radio-frequency (rf) power conditions in order to experimentally study the change in the work function. Control of the rf power could change the work function of graphene from 4.91?eV to 4.37?eV. It is shown that the increased rf power may lead to the increased number of graphitic nitrogen, increasing the electron concentration, and shifting the Fermi level to higher energy. The ability to controllably tune the work function of graphene is essential for optimizing the efficiency of optoelectronic and electronic devices.

Zeng, Jian-Jhou; Lin, Yow-Jon, E-mail: rzr2390@yahoo.com.tw [Institute of Photonics, National Changhua University of Education, Changhua 500, Taiwan (China)

2014-06-09T23:59:59.000Z

174

A prototype system for detecting the radio-frequency pulse associated with cosmic ray air showers  

E-Print Network [OSTI]

The development of a system to detect the radio-frequency (RF) pulse associated with extensive air showers of cosmic rays is described. This work was performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array. A small subset of data (less than 40 out of a total of 600 hours of running time), taken under low-noise conditions, permitted upper limits to be placed on the rate for pulses accompanying showers of energies around $10^{17}$ eV.

Green, K; Suprun, D A; Wilkerson, J F; Green, Kevin; Rosner, Jonathan L.; Suprun, Denis A.

2003-01-01T23:59:59.000Z

175

A prototype system for detecting the radio-frequency pulse associated with cosmic ray air showers  

E-Print Network [OSTI]

The development of a system to detect the radio-frequency (RF) pulse associated with extensive air showers of cosmic rays is described. This work was performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array. A small subset of data (less than 40 out of a total of 600 hours of running time), taken under low-noise conditions, permitted upper limits to be placed on the rate for pulses accompanying showers of energies around $10^{17}$ eV.

Kevin Green; Jonathan L. Rosner; Denis A. Suprun; J. F. Wilkerson

2003-04-14T23:59:59.000Z

176

VLBA Multi-frequency Polarimetric imaging of Radio-loud Broad Absorption Line Quasars  

E-Print Network [OSTI]

We conducted the first multi-frequency polarimetric imaging of four broad absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond resolutions to investigate the inclination of the non-thermal jet and test the hypothesis that radio sources in BAL quasars are still young. Among these four sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in parsec scales, and polarized emission detected in the core. These characteristics are consistent with those of blazars. We set constraints on viewing angles to $wind.

Hayashi, Takayuki J; Nagai, Hiroshi

2013-01-01T23:59:59.000Z

177

A new Main Injector radio frequency system for 2.3 MW Project X operations  

SciTech Connect (OSTI)

For Project X Fermilab Main Injector will be required to provide up to 2.3 MW to a neutrino production target at energies between 60 and 120 GeV. To accomplish the above power levels 3 times the current beam intensity will need to be accelerated. In addition the injection energy of Main Injector will need to be as low as 6 GeV. The current 30 year old Main Injector radio frequency system will not be able to provide the required power and a new system will be required. The specifications of the new system will be described.

Dey, J.; Kourbanis, I.; /Fermilab

2011-03-01T23:59:59.000Z

178

An investigation of the usefulness of extremely low-frequency electromagnetic measurements for treaty verification  

SciTech Connect (OSTI)

From FY 1986 through FY 1988, we monitored extremely low-frequency (ELF) electromagnetic (EM) fields to determine whether these signals could be detected from underground nuclear explosions. Signals clearly related to underground tests were detected only when the ELF field sensors were located within 10 km of surface ground zero. Theoretical analysis, based on the results of these measurements, shows that the ELF impulse signals from underground nuclear tests are of longer duration than those from lightning sources and are, therefore, less efficient in exciting resonances in the earth-ionosphere cavity, even though the source strength for each may be the same. Thus, ELF signals from underground nuclear tests with yields of <150 kT are generally lower than the background signals caused by worldwide lightning activity. Our conclusion is that ELF monitoring probably will not be useful for detecting underground nuclear tests at distances >10 km from the tests. 16 refs., 24 figs., 3 tabs.

Sweeney, J.J.

1989-01-01T23:59:59.000Z

179

Laser frequency stabilization to excited state transitions using electromagnetically induced transparency in a cascade system  

SciTech Connect (OSTI)

We demonstrate laser frequency stabilization to excited state transitions using cascade electromagnetically induced transparency. Using a room temperature Rb vapor cell as a reference, we stabilize a first diode laser to the D{sub 2} transition and a second laser to a transition from the intermediate 5P{sub 3/2} state to a highly excited state with principal quantum number n=19-70. A combined laser linewidth of 280{+-}50 kHz over a 100 {mu}s time period is achieved. This method may be applied generally to any cascade system and allows laser stabilization to an atomic reference in the absence of a direct absorption signal.

Abel, R. P.; Mohapatra, A. K.; Bason, M. G.; Pritchard, J. D.; Weatherill, K. J.; Raitzsch, U.; Adams, C. S. [Department of Physics, Durham University, Rochester Building, South Road, Durham DH1 3LE (United Kingdom)

2009-02-16T23:59:59.000Z

180

Nonlinear Electrodynamics: Alternative Field Theory for Featuring Photon Propagation Over Weak Background Electromagnetic Fields and what Earth Receivers Read off Radio Signals from Interplanetary Spacecraft Transponders  

E-Print Network [OSTI]

A few observational and/or experimental results have dramatically pushed forward the research program on gravity as those from the radio-metric Doppler tracking received from the Pioneer 10 and 11 spacecrafts when the space vehicles were at heliocentric distances between 20 and 70 Astronomical Units (AU). These data have conclusively demonstrated the presence of an anomalous, tiny and blue-shifted frequency drift that changes smoothly at a rate of $ \\sim 6 \\times 10^{-9}$ Hz s$^{-1}$. Those signals, if interpreted as a gravitational pull of the Sun on each Pioneer vehicle, translates into a deceleration of $a_P = (8.74\\pm 1.33) \\times 10^{-10}$ m s$^{-2}$. This Sunward acceleration appears to be a violation of Newton's inverse-square law of gravitation, and is referred to as the Pioneer anomaly, the nature of which remains still elusive to unveil. Within the theoretical framework of nonlinear electrodynamics (NLED) in what follows we will address this astrodynamics puzzle, which over the last fifteen years has challenged in a fundamental basis our understanding of gravitational physics. To this goal we will first, and briefly, review the history of the Pioneers 10 and 11 missions. Then a synopsis of currently available Lagrangian formulations of NLED is given. And finally, we present our solution of this enigma by invoking a special class of NLED theories featuring a proper description of electromagnetic phenomena taking place in environments where the strength of the (electro)magnetic fields in the background is decidedly low.

Herman J. Mosquera Cuesta

2011-05-13T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Phase-Resolved Measurements of Ion Velocity in a Radio-Frequency Sheath Brett Jacobs,1,* Walter Gekelman,1  

E-Print Network [OSTI]

-induced fluorescence in a commercial plasma process- ing tool. Discharge parameters were such that the 2.2 MHz rf upon the ratio of the ion transit time through the sheath to the rf period (ion=rf) [11]. In the high-frequencyPhase-Resolved Measurements of Ion Velocity in a Radio-Frequency Sheath Brett Jacobs,1,* Walter

California at Los Angles, University of

182

2-dimensional ion velocity distributions measured by laser-induced fluorescence above a radio-frequency biased silicon wafer  

E-Print Network [OSTI]

2-dimensional ion velocity distributions measured by laser-induced fluorescence above a radio-frequency cm diameter, 2.2 MHz-biased silicon wafer in a commercial inductively coupled plasma processing rf frequencies,5­7,18 non-sinusoidal waveforms8 and pulsed power.9,19 Control of IEDs in many

California at Los Angles, University of

183

Presented at "RFI2004: Workshop on Mitigation of Radio Frequency Interference in Radio Astronomy"; Penticton, Canada, 16-18 July 2004  

E-Print Network [OSTI]

"; Penticton, Canada, 16-18 July 2004 "Quiet, please!" - regulatory protection strategies for the SKA Wim van of the large financial investment foreseen in the Square Kilometre Array (SKA) radio telescope, it will need sensitive observations outside the frequency bands allocated by the International Telecommunication Union

Ellingson, Steven W.

184

Density-dependent response of an ultracold plasma to few-cycle radio-frequency pulses  

Science Journals Connector (OSTI)

Ultracold neutral plasmas exhibit a density-dependent resonant response to applied radio-frequency (rf) fields in the frequency range of several to hundreds of megahertz for achievable densities. We have conducted measurements where short bursts of an rf fieldwere applied to these plasmas, with pulse durations as short as two cycles. We still observed a density-dependent resonant response to these short pulses, but the time scale of the response is too short to be consistent with local heating of electrons in the plasma from collisions under a range of experimental parameters. Instead, our results are consistent with rapid energy transfer to individual electrons from electric fields resulting from an overall displacement of the electron cloud from the ions during the collective motion of the electrons. This collective motion was also observed by applying two sharp electric field pulses separated in time to the plasma. These measurements demonstrate the importance of collective motion in the energy transport in these systems.

Truman M. Wilson; Wei-Ting Chen; Jacob L. Roberts

2013-01-14T23:59:59.000Z

185

Contactless measurement of nonlinear conductivity in the radio-frequency range  

E-Print Network [OSTI]

We have developed a system for contactless measurement of nonlinear conductivity in the radio-frequency band, and over a wide temperature range. A non-resonant circuit is used to electrically excite the sample, and the induced signal is detected by a resonant circuit whose natural frequency matches higher harmonics of the excitation. A simple modification of the probe allows non-resonant detection suitable for stronger signals. Two measurement procedures are proposed that allow significant excitation power variation, up to 150 W. The apparatus has been validated trough the measurement of the nonlinear response at the superconducting transition of a high-Tc superconductor, and the nematic transition of an iron pnictide.

Došli?, Marija; Požek, Miroslav

2014-01-01T23:59:59.000Z

186

Sheath model for radio-frequency-biased, high-density plasmas valid for all ?/?i  

Science Journals Connector (OSTI)

A model is proposed for sheaths in high-density discharges, with radio-frequency (rf) bias applied at frequencies ? comparable to ?i, the ion plasma frequency at the edge of the sheath. The model treats ion dynamics using fluid equations, including all time-dependent terms. Model predictions for current, impedance, and power were compared to measurements performed in high-density discharges in argon at 1.33 Pa (10 mTorr) at rf bias frequencies from 0.1 to 10 MHz (?/?i from 0.006 to 1.8) and rf bias voltages from 1 to 200 V. Model predictions were in good agreement with measurements, much better than that obtained by models that neglect time-dependent ion dynamics. In particular, differences of as much as 40–50 % between power measurements and the power predicted by previous models are now explained and eliminated. The model also explains why methods of extracting plasma parameters from electrical measurements using previous sheath models may fail, and it suggests more accurate methods of extracting these parameters.

Mark A. Sobolewski

2000-12-01T23:59:59.000Z

187

Intelligent Spectrum Sensor Radio.  

E-Print Network [OSTI]

??A cognitive radio is a radio with built-in intelligence that makes it able to utilize the radio frequency spectrum more efficiently by adapting to the… (more)

Mian, Omer

2008-01-01T23:59:59.000Z

188

Characterization and tribological application of diamond-like carbon (DLC) films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique  

Science Journals Connector (OSTI)

Diamond-like carbon (DLC) films were successfully prepared on glass substrates and surfaces of selenium drums via radio frequency plasma enhanced chemical vapor deposition method. The...

Ning Cao; Zhen-yi Fei; Yong-xin Qi; Wen-wen Chen…

2009-12-01T23:59:59.000Z

189

Reclamation of niobium compounds from ionic liquid electrochemical polishing of superconducting radio frequency cavities  

SciTech Connect (OSTI)

Recent research has shown that choline chloride (vitamin B4)-based solutions can be used as a greener alternative to acid-based electrochemical polishing solutions. This study demonstrated a successful method for electrochemical deposition of niobium compounds onto the surface of copper substrates using a novel choline chloride-based ionic liquid. Niobium ions present in the ionic liquid solution were dissolved into the solution prior to deposition via electrochemical polishing of solid niobium. A black coating was clearly visible on the surface of the Cu following deposition. This coating was analyzed using scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and X-ray fluorescence spectroscopy (XRF). This ionic liquid-based electrochemical deposition method effectively recycles previously dissolved niobium from electrochemical polishing of superconducting radio frequency (SRF) cavities.

Wixtrom, Alex I. [Christopher Newport University, Newport News, VA (United States); Buhler, Jessica E. [Christopher Newport University, Newport News, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Abdel-Fattah, Tarek M. [Christopher Newport University, Newport News, VA (United States)

2013-06-01T23:59:59.000Z

190

Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge  

Science Journals Connector (OSTI)

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O2/Ar. With respect to the influence of oxygen component when diluted into argon plasmadischarge on the dischargecharacteristics the measurements of the electrical parameters (impedance phase angle resistance and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy(OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

Shou-Zhe Li; Qi Wu; Wen Yan; Dezhen Wang; Han S. Uhm

2011-01-01T23:59:59.000Z

191

Low-Level Radio Frequency System Development for the National Synchrotron Light Source II  

SciTech Connect (OSTI)

The National Synchrotron Light Source-II (NSLS-II) is a new ultra-bright 3GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. The position and timing specifications of the ultra-bright photon beam imposes a set of stringent requirements on the performance of radio frequency (RF) control. In addition, commissioning and staged installation of damping wigglers and insertion devices requires the flexibility of handling varying beam conditions. To meet these requirements, a digital implementation of the LLRF is chosen, and digital serial links are planned for the system integration. The first prototype of the controller front-end hardware has been built, and is currently being tested.

Ma,H.; Rose, J.

2009-05-04T23:59:59.000Z

192

Radio-frequency dispersive detection of donor atoms in a field-effect transistor  

SciTech Connect (OSTI)

Radio-frequency dispersive read-out can provide a useful probe to nano-scale structures, such as nano-wire devices, especially, when the implementation of charge sensing is not straightforward. Here, we demonstrate dispersive “gate-only” read-out of phosphor donors in a silicon nano-scale transistor. The technique enables access to states that are only tunnel-coupled to one contact, which is not easily achievable by other methods. This allows us to locate individual randomly placed donors in the device channel. Furthermore, the setup is naturally compatible with high bandwidth access to the probed donor states and may aid the implementation of a qubit based on coupled donors.

Verduijn, J., E-mail: a.verduijn@unsw.edu.au; Rogge, S. [Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney NSW 2052 (Australia)] [Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney NSW 2052 (Australia); Vinet, M. [CEA/LETI-MINATEC, CEA-Grenoble, 17 rue des martyrs, F-38054 Grenoble (France)] [CEA/LETI-MINATEC, CEA-Grenoble, 17 rue des martyrs, F-38054 Grenoble (France)

2014-03-10T23:59:59.000Z

193

Spatial distribution of the plasma parameters in a radio-frequency driven negative ion sourcea)  

Science Journals Connector (OSTI)

Results from initial stage of modeling of the SPIDER source of negative hydrogen/deuterium ions currently under development in Consorzio RFX (Padova) regarding ITER are presented. A 2D model developed within the fluid plasma theory for low-pressure discharges (free-fall regime maintenance) is applied to the gas-discharge conditions planned and required for the SPIDER source: gas pressure of 0.3 Pa and radio-frequency (rf) power of 100 kW absorbed in a single driver. The results are for the spatial distribution of the plasma characteristics (charged particle densities electron temperature and electron energy flux plasma potential and dc electric field) with conclusions for the role of the electron energy flux in the formation of the discharge structure.

D. Todorov; Kh. Tarnev; Ts. Paunska; St. Lishev; A. Shivarova

2014-01-01T23:59:59.000Z

194

Collisionless electron heating by radio frequency bias in low gas pressure inductive discharge  

SciTech Connect (OSTI)

We show experimental observations of collisionless electron heating by the combinations of the capacitive radio frequency (RF) bias power and the inductive power in low argon gas pressure RF biased inductively coupled plasma (ICP). With small RF bias powers in the ICP, the electron energy distribution (EED) evolved from bi-Maxwellian distribution to Maxwellian distribution by enhanced plasma bulk heating and the collisionless sheath heating was weak. In the capacitive RF bias dominant regime, however, high energy electrons by the RF bias were heated on the EEDs in the presence of the ICP. The collisionless heating mechanism of the high energy electrons transited from collisionless inductive heating to capacitive coupled collisionless heating by the electron bounce resonance in the RF biased ICP.

Lee, Hyo-Chang; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

2012-12-10T23:59:59.000Z

195

Verification of particle simulation of radio frequency waves in fusion plasmas  

SciTech Connect (OSTI)

Radio frequency (RF) waves can provide heating, current and flow drive, as well as instability control for steady state operations of fusion experiments. A particle simulation model has been developed in this work to provide a first-principles tool for studying the RF nonlinear interactions with plasmas. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation. This model has been implemented in a global gyrokinetic toroidal code using real electron-to-ion mass ratio. To verify the model, linear simulations of ion plasma oscillation, ion Bernstein wave, and lower hybrid wave are carried out in cylindrical geometry and found to agree well with analytic predictions.

Kuley, Animesh; Lin, Z. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States) [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Fusion Simulation Center, Peking University, Beijing 100871 (China); Wang, Z. X. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)] [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Wessel, F. [Tri Alpha Energy, Inc., Post Office Box 7010, Rancho Santa Margarita, California 92688 (United States)] [Tri Alpha Energy, Inc., Post Office Box 7010, Rancho Santa Margarita, California 92688 (United States)

2013-10-15T23:59:59.000Z

196

A large gap of radio frequency dielectric barrier atmospheric pressure glow discharge  

SciTech Connect (OSTI)

A large gap was acquired between electrodes (up to 5.5 mm) of Ar atmospheric pressure glow discharge in radio frequency dielectric barrier discharge (rf-DBD). The discharge of Ar plasma was characterized by I-V curve and Lissajous plot, and the effective power of the discharge was calculated based on the measured Lissajous plot and found to be higher than 90% of the input power. To gain a thorough understanding of the mechanism, the rf-DBD with a single dielectric barrier layer operating in gamma mode glow discharge of N{sub 2} plasma was diagnosed in spatial resolution through optical emission spectroscopy. It was concluded that secondary electron emission might be responsible for the sustainable glow discharge in the large gap rf-DBD plasma.

Li, B.; Chen, Q.; Liu, Z. W. [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 102600 (China)

2010-01-25T23:59:59.000Z

197

Structure control of carbon nanotubes using radio-frequency plasma enhanced chemical vapor deposition  

Science Journals Connector (OSTI)

Carbon nanotube structures such as tube diameter, growth site, and formation density are controlled using radio-frequency (RF, 13.56 MHz) plasma enhanced chemical vapor deposition (RF-PECVD) method. We have produced uniformly well-aligned multi-walled carbon nanotubes (MWNTs) grown over the large scale area and linearly arrayed \\{MWNTs\\} grown in a selected area without any highly-sophisticated patterning process. In our RF-PECVD experiment, furthermore, individually grown single-walled carbon nanotubes (SWNTs) or their thin bundles are synthesized for the first time within the scope of the PECVD methods. These results indicate that PECVD method provides the high potential for the further development of nano-technology.

T. Kato; G.-H. Jeong; T. Hirata; R. Hatakeyama

2004-01-01T23:59:59.000Z

198

Temporally resolved ion velocity distribution measurements in a radio-frequency plasma sheath  

SciTech Connect (OSTI)

The ion velocity distribution function (IVDF) above and within a radio-frequency (RF) biased plasma sheath is studied experimentally with a pulsed laser-induced fluorescence diagnostic in an industrial plasma etch tool. Temporally resolved measurements taken at eight different phases of the 2.2 MHz bias waveform show that the ion dynamics vary dramatically throughout the RF cycle (the ratio of the average ion transit time through the sheath to the RF period is {tau}{sub ion}/{tau}{sub RF} = 0.3). The position of the presheath/sheath edge is constant throughout the RF cycle and the time-averaged ion flux is conserved within the sheath region. The characteristic bimodal structure of the time-averaged ion distributions found in previous experiments is observed to arise from the time-dependent ion dynamics, in accord with existing theory. The large temporal variation of the IVDF has implications for the plasma chemistry and etching quality.

Jacobs, B.; Gekelman, W.; Pribyl, P. [University of California, Los Angeles, California 90095 (United States); Barnes, M. [MS Barnes Engineering, San Ramon, California 94583 (United States)

2011-05-15T23:59:59.000Z

199

Numerical investigation of pulse-modulated atmospheric radio frequency discharges in helium under different duty cycles  

SciTech Connect (OSTI)

Experiments observed that the pulse duty cycle has effects on the plasma homogeneity in pulse-modulated radio frequency (rf) discharges. In this paper, pulse-modulated rf (13.56 MHz) helium discharges are theoretically investigated using a two dimensional fluid model. With the pulse period being fixed to 15 {mu}s, it is found that when the pulse-on duration is over 4 {mu}s, i.e., the duty cycle is larger than approximately 27%, the discharge transits from an inhomogeneous to a homogeneous mode in every specific part of each pulse cycle under currently-used simulation parameters. More quantitative analysis shows that the discharge becomes more homogeneous as the duty cycle is increased but does not reach complete homogeneity. Possible reasons for the homogeneity improvement are discussed.

Sun Jizhong; Ding Zhengfen; Li Xuechun; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Wang Qi [Dalian Institute of Semiconductor Technology, School of Electronics Science and Technology, Dalian University of Technology, Dalian 116023 (China)

2011-12-15T23:59:59.000Z

200

Radio-frequency sheath-plasma interactions with magnetic field tangency points along the sheath surface  

SciTech Connect (OSTI)

Computer simulations of radio-frequency (RF) waves propagating across a two-dimensional (2D) magnetic field into a conducting boundary are described. The boundary condition for the RF fields at the metal surface leads to the formation of an RF sheath, which has previously been studied in one-dimensional models. In this 2D study, it is found that rapid variation of conditions along the sheath surface promote coupling of the incident RF branch (either fast or slow wave) to a short-scale-length sheath-plasma wave (SPW). The SPW propagates along the sheath surface in a particular direction dictated by the orientation of the magnetic field with respect to the surface, and the wave energy in the SPW accumulates near places where the background magnetic field is tangent to the surface.

Kohno, H. [Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015 (United States)] [Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015 (United States); Myra, J. R.; D'Ippolito, D. A. [Lodestar Research Corporation, 2400 Central Avenue P-5, Boulder, Colorado 80301 (United States)] [Lodestar Research Corporation, 2400 Central Avenue P-5, Boulder, Colorado 80301 (United States)

2013-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
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201

Particle-in-cell simulation of hydrogen discharge driven by combined radio frequency and pulse sources  

SciTech Connect (OSTI)

A particle-in-cell plus Monte Carlo collision model is employed to investigate the low pressure hydrogen capacitive discharge driven by combined radio frequency (rf) and pulse sources. This work focuses on the evolutions of electron energy and density in the discharge to illustrate the role that a short pulse source plays. The simulation results show that an extra short pulse source can modulate the electron energy effectively: in the early and late pulse-on times, the electron energy is much higher than that in the single rf source discharge; during the pulse-off time, the electron energy can drop gradually to a low value. It is also found that a few peaks of attenuated electron energy appear periodically just after the pulse voltage drops to zero. The similar phenomena can also be found in the production rate of highly vibrationally excited hydrogen molecules. Physical mechanisms responsible for these phenomena are discussed.

Sun Jizhong; Li Xiantao; Sang Chaofeng; Jiang Wei; Zhang Pengyun; Wang Dezhen [School of Physics and Optoelectronic Engineering and College of Advanced Science and Technology, Dalian University of Technology, Dalian 116024 (China)

2010-10-15T23:59:59.000Z

202

Dynamic model of the radio-frequency plasma sheath in a highly asymmetric discharge cell  

Science Journals Connector (OSTI)

A self-consistent fluid model for the radio-frequency sheath at the powered electrode of a highly asymmetric discharge cell is developed and solved. The model assumes time-independent ion motion and inertialess electrons. The voltage on the powered electrode, assumed to be sinusoidal, is shared between the powered sheath and a series resistance that represents the remainder of the discharge. The model includes ion collisions, sheath conduction currents, and secondary electron emission from the electrode surface. Model results are compared with previous sheath models and with experiment. Current wave forms predicted by the model closely resemble the nonsinusoidal current wave forms measured in highly asymmetric cells. The model accurately predicts the shape of sheath voltage wave forms, but not their dc components. The magnitudes and phases of sheath impedances predicted by the model agree with experimental measurements performed in argon discharges at pressures of 4.0–133 Pa.

M. A. Sobolewski

1997-07-01T23:59:59.000Z

203

The parameters of electron cyclotron resonance/radio-frequency hybrid hydrogen plasma adjusted by substrate arrangements  

SciTech Connect (OSTI)

Hybrid hydrogen plasma was formed by biasing 13.56 MHz radio-frequency (rf) power on a substrate immersed in 2.45 GHz microwave electron cyclotron resonance (ECR) plasma. The influences of the substrate configuration on plasma characteristics were investigated. With increasing rf self-bias voltage, electron temperature, T{sub e}, increases obviously in the case of the single-electrode substrate, whereas a slight change in T{sub e} was observed with the double-electrode substrate condition. Electron density rises almost with a same magnitude under both two substrate conditions. It exhibited that electron energy and density in ECR-rf hybrid mode could be adjusted independently by controlling rf discharge with favorable substrate configurations.

Zhou, H. Y.; Wang, L.; Zhu, X. D.; Ke, B.; Ding, F.; Wen, X. H. [CAS Key Laboratory of Basic Plasma Physics, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Y. N. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

2010-03-15T23:59:59.000Z

204

Resonance Cone Interaction With a Self-Consistent Radio-Frequency Sheath  

Science Journals Connector (OSTI)

We study the propagation of lower-hybrid-type resonance cones in a tenuous magnetized plasma, and, in particular, their interaction with, and reflection from, the plasma sheath near a conducting wall. The sheath is modeled as a vacuum gap whose width is given by the Child-Langmuir law. The application of interest is when the resonance cones are launched (parasitically) by an ion-cyclotron radio-frequency antenna in a typical rf-heated tokamak fusion experiment. We calculate the fraction of launched voltage in the resonance cones that is transmitted to the sheath, and show that it has a sensitive thresholdlike turn on when a critical parameter reaches order unity. Above threshold, the fractional voltage transmitted to the sheath is order unity, leading to strong and potentially deleterious rf-wall interactions in tokamak rf heating experiments. Below threshold, these interactions can be avoided.

J. R. Myra and D. A. D’Ippolito

2008-11-06T23:59:59.000Z

205

Supersonic combustion of a transverse injected H sub 2 jet in a radio frequency heated flow  

SciTech Connect (OSTI)

The combustion of a single hydrogen jet, normally injected into a radio frequency (RF) heated, oxidant-containing, supersonic flow, has been established to characterize the chemical and fluid dynamic phenomena associated with the reaction process and ultimately validate the predictive capability of computational computer dynamic (CFD) codes. The experimental system employed for this study is unique in that it uses an electrodeless, inductively coupled plasma tube to generate the high temperature oxidant-containing gas for subsequent nozzle expansion. Advantages of an RF heated flow system include reduced free-stream chemical contamination, continuous operation, and relative ease of integration into a typical flow laboratory environment. A description of the system utilized for this study is presented including preliminary results of the reactive flow characterization. In addition, the use of the laser-based diagnostic techniques, such as planar laser-induced fluorescence (PLIF), for measuring flow properties is also discussed. 8 refs., 7 figs.

Wantuck, P.J.; Tennant, R.A.; Watanabe, H.H.

1991-01-01T23:59:59.000Z

206

LOW-FREQUENCY OBSERVATIONS OF TRANSIENT QUASI-PERIODIC RADIO EMISSION FROM THE SOLAR ATMOSPHERE  

SciTech Connect (OSTI)

We report low-frequency observations of quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was ?5.2 s, and their average degree of circular polarization (dcp) was ?0.12. We calculated the associated magnetic field B (1) using the empirical relationship between the dcp and B for the harmonic type III emission, and (2) from the observed quasi-periodicity of the bursts. Both the methods result in B ? 4.2 G at the location of the 80 MHz plasma level (radial distance r ? 1.3 R{sub ?}) in the active region corona.

Sasikumar Raja, K.; Ramesh, R., E-mail: sasikumar@iiap.res.in [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034 (India)

2013-09-20T23:59:59.000Z

207

Coupled microwave ECR and radio-frequency plasma source for plasma processing  

DOE Patents [OSTI]

In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm[sup 2] at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance. 4 figures.

Tsai, C.C.; Haselton, H.H.

1994-03-08T23:59:59.000Z

208

High power water load for microwave and millimeter-wave radio frequency sources  

DOE Patents [OSTI]

A high power water load for microwave and millimeter wave radio frequency sources has a front wall including an input port for the application of RF power, a cylindrical dissipation cavity lined with a dissipating material having a thickness which varies with depth, and a rear wall including a rotating reflector for the reflection of wave energy inside the cylindrical cavity. The dissipation cavity includes a water jacket for removal of heat generated by the absorptive material coating the dissipation cavity, and this absorptive material has a thickness which is greater near the front wall than near the rear wall. Waves entering the cavity reflect from the rotating reflector, impinging and reflecting multiple times on the absorptive coating of the dissipation cavity, dissipating equal amounts of power on each internal reflection.

Ives, R. Lawrence (Saratoga, CA); Mizuhara, Yosuke M. (Palo Alto, CA); Schumacher, Richard V. (Sunnyvale, CA); Pendleton, Rand P. (Saratoga, CA)

1999-01-01T23:59:59.000Z

209

Push-pull radio frequency circuit with integral transistion to waveguide output  

DOE Patents [OSTI]

A radio frequency circuit for ICRF heating includes a resonant push-pull circuit, a double ridged rectangular waveguide, and a coupling transition which joins the waveguide to the resonant circuit. The resonant circuit includes two cylindrical conductors mounted side by side and two power vacuum tubes attached to respective ends of a cylindrical conductor. A conductive yoke is located at the other end of the cylindrical conductors to short circuit the two cylindrical conductors. The coupling transition includes two relatively flat rectangular conductors extending perpendicular to the longitudinal axes of a respective cylindrical conductor to which the flat conductor is attached intermediate the ends thereof. Conductive side covers and end covers are also provided for forming pockets in the waveguide into which the flat conductors extend when the waveguide is attached to a shielding enclosure surrounding the resonant circuit.

Bennett, Wilfred P. (21 Catskill Ct., Belle Mead, NJ 08502)

1987-01-01T23:59:59.000Z

210

Laser polishing of niobium for application to superconducting radio frequency cavities  

SciTech Connect (OSTI)

Superconducting radio frequency niobium cavities are at the heart of an increasing number of particle accelerators. Their performance is dominated by a several nanometer thick layer at the interior surface. Maximizing the smoothness of this surface is critical, and aggressive chemical treatments are now employed to this end. The authors describe laser-induced surface melting as an alternative 'greener' approach. Selection of laser parameters guided by modeling achieved melting that reduced the surface roughness from the fabrication process. The resulting topography was examined by scanning electron microscope and atomic force microscope (AFM). Plots of power spectral density computed from the AFM data give further insight into the effect of laser melting on the topography of the mechanically polished (only) niobium.

Singaravelu, Senthil; Klopf, John Michael; Xu, Chen; Krafft, Geoffrey; Kelley, Michael J.

2012-09-01T23:59:59.000Z

211

Efficient Inversion of Mult-frequency and Multi-Source Electromagnetic Data  

SciTech Connect (OSTI)

The project covered by this report focused on development of efficient but robust non-linear inversion algorithms for electromagnetic induction data, in particular for data collected with multiple receivers, and multiple transmitters, a situation extremely common in eophysical EM subsurface imaging methods. A key observation is that for such multi-transmitter problems each step in commonly used linearized iterative limited memory search schemes such as conjugate gradients (CG) requires solution of forward and adjoint EM problems for each of the N frequencies or sources, essentially generating data sensitivities for an N dimensional data-subspace. These multiple sensitivities allow a good approximation to the full Jacobian of the data mapping to be built up in many fewer search steps than would be required by application of textbook optimization methods, which take no account of the multiplicity of forward problems that must be solved for each search step. We have applied this idea to a develop a hybrid inversion scheme that combines features of the iterative limited memory type methods with a Newton-type approach using a partial calculation of the Jacobian. Initial tests on 2D problems show that the new approach produces results essentially identical to a Newton type Occam minimum structure inversion, while running more rapidly than an iterative (fixed regularization parameter) CG style inversion. Memory requirements, while greater than for something like CG, are modest enough that even in 3D the scheme should allow 3D inverse problems to be solved on a common desktop PC, at least for modest (~ 100 sites, 15-20 frequencies) data sets. A secondary focus of the research has been development of a modular system for EM inversion, using an object oriented approach. This system has proven useful for more rapid prototyping of inversion algorithms, in particular allowing initial development and testing to be conducted with two-dimensional example problems, before approaching more computationally cumbersome three-dimensional problems.

Gary D. Egbert

2007-03-22T23:59:59.000Z

212

Effect of excitation frequency on source characteristics in radio frequency glow discharge atomic emission spectrometry-I. 2–30 \\{MHz\\}  

Science Journals Connector (OSTI)

The role of excitation frequency on the electrical, atomization, and optical emission characteristics of a radio frequency glow discharge atomic emission (rf-GD-AES) source was investigated in the frequency range of 2–30 MHz. Comparisons between the applied (peak-to-peak) potentials and the resultant dc bias potentials indicate that the discharge energy is dissipated more at the sample surface at lower frequencies and in the negative glow region in the upper frequency range. As a result, sputtering rates are greatest at the lowest frequency (2 MHz). The response of a variety of Cu I and II emission transitions to changes in frequency illustrates the need to choose separately the analytical transitions at a given frequency. In general, however, high-lying transitions optimize at low frequencies, with resonant transitions showing enhancements at high ones. As such, the operating frequency has a somewhat diametric effect on atomization and excitation characteristics. Finally, analytical figures of merit are illustrated for a number of analytes and transitions in a copper standard. While differences exist in the response of line intensity to operating frequency, background levels decrease and stability of the plasma improves with increased frequency.

Chris Lazik; R.Kenneth Marcus

1994-01-01T23:59:59.000Z

213

Argon metastable densities in radio frequency Ar, Ar/O2 and Ar/CF4 electrical discharges  

E-Print Network [OSTI]

Argon metastable densities in radio frequency Ar, Ar/O2 and Ar/CF4 electrical discharges Shahid. In this article, we present results from a two-dimensional computer simulation of Ar, Ar/O2, and Ar/CF4 discharges in the ambipolar electric field resulting from electrode structures. Additions of small amounts of O2 and CF4

Kushner, Mark

214

Sheet resistance of LiNbO3 wafers processed in radio-frequency plasma of hydrogen  

Science Journals Connector (OSTI)

Radio-frequency discharge of 13.56MHz in hydrogen was...3...wafers under an electrodeless capacitive coupling. At a pressure of 0.5 torr and RF input power of 250 W a surface...3...wafers was created in which the...

H. Tur?i?ová; J. Pracha?ová; J. ?ervená; J. Vacík

2000-03-01T23:59:59.000Z

215

Design of multi-channel radio-frequency front-end for 200mhz parallel magnetic resonance imaging  

E-Print Network [OSTI]

increases to 64 or even 128, the traditional method of stacking the same number of radio-frequency (RF) receivers with very low level of integration becomes expensive and cumbersome. However, the cost, size, power consumption of the Parallel MRI receivers...

Liu, Xiaoqun

2009-05-15T23:59:59.000Z

216

Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics  

SciTech Connect (OSTI)

This paper presents a systematic characterization of capacitively coupled radio-frequency hydrogen discharges, produced within a parallel plate cylindrical setup at different rf applied voltages (V{sub rf}=50-600 V), frequencies (f=13.56-40.68 MHz), and pressures (p=0.2-1 torr). A two-dimensional, time-dependent fluid model for charged particle transport is self-consistently solved coupled to a homogeneous kinetic model for hydrogen, including vibrationally excited molecular species and electronically excited atomic species. Numerical simulations are compared with experimental measurements of various plasma parameters. A good quantitative agreement is found between simulations and experiment for the coupled electrical power and the plasma potential. The model underestimates the values of the electron density, the self-bias potential, and the H(n=1) atom density with respect to measurements, but agrees with experiment when predicting that all these parameters increase with either V{sub rf}, f, or p. The dissociation degree is about 10{sup -3} for the work conditions considered. Simulations adopt a wall recombination probability for H atoms that was experimentally measured, thus accounting for surface modification with discharge operating conditions. Results show the key role played by the atomic wall recombination mechanism in plasma description.

Marques, L.; Jolly, J.; Alves, L. L. [Departamento de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal)

2007-09-15T23:59:59.000Z

217

System efficiency analysis for high power solid state radio frequency transmitter  

SciTech Connect (OSTI)

This paper examines some important relationships, related with the system efficiency, for very high power, radio frequency solid-state transmitter; incorporating multiple solid-state power amplifier modules, power combiners, dividers, couplers, and control/interlock hardware. In particular, the characterization of such transmitters, at the component as well as the system level, is discussed. The analysis for studying the influence of the amplitude and phase imbalance, on useful performance parameters like system efficiency and power distribution is performed. This analysis is based on a scattering parameter model. This model serves as a template for fine-tuning the results, with the help of a system level simulator. For experimental study, this approach is applied to a recently designed modular and scalable solid-state transmitter, operating at the centre frequency of 505.8?MHz and capable of delivering a continuous power of 75 kW. Such first time presented, system level study and experimental characterization for the real time operation will be useful for the high power solid-state amplifier designs, deployed in particle accelerators.

Jain, Akhilesh, E-mail: ajain@rrcat.gov.in; Sharma, D. K.; Gupta, A. K.; Lad, M. R.; Hannurkar, P. R. [RF Systems Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)] [RF Systems Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Pathak, S. K. [Electromagnetics and Microwave Engineering, Institute for Plasma Research, Gandhinagar 382 428 (India)] [Electromagnetics and Microwave Engineering, Institute for Plasma Research, Gandhinagar 382 428 (India)

2014-02-15T23:59:59.000Z

218

Excitation and propagation of electromagnetic fluctuations with ion-cyclotron range of frequency in magnetic reconnection laboratory experiment  

SciTech Connect (OSTI)

Large-amplitude electromagnetic fluctuations of ion-cyclotron-frequency range are detected in a laboratory experiment inside the diffusion region of a magnetic reconnection with a guide field. The fluctuations have properties similar to kinetic Alfvén waves propagating obliquely to the guide field. Temporary enhancement of the reconnection rate is observed during the occurrence of the fluctuations, suggesting a relationship between the modification in the local magnetic structure given by these fluctuations and the intermittent fast magnetic reconnection.

Inomoto, Michiaki; Tanabe, Hiroshi; Ono, Yasushi [Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan)] [Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Kuwahata, Akihiro [Graduate School of Engineering, The University of Tokyo,7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)] [Graduate School of Engineering, The University of Tokyo,7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Collaboration: TS Group

2013-06-15T23:59:59.000Z

219

Effects of Scattering on Radio Emission from the Quiet Sun at Low Frequencies  

Science Journals Connector (OSTI)

The observations of the quiet Sun at meter and decameter wavelengths show that its brightness temperatures can be ~1 order of magnitude lower than the expected values of 106 K and the apparent diameters can be very large. We examine whether this unusual behavior is due to refraction in the smoothly varying coronal plasma and scattering by random density fluctuations using an improved Monte Carlo simulation technique. We use a three-dimensional model for the electron density, -->Ne, and a power-law spectrum for the density fluctuations with an exponential index of ?. We consider two cases: (1) -->? = 11/3 (Kolmogorov spectrum), relative level of density fluctuations --> = ? Ne/Ne = 0.1, and scale heights ranging from the inner scale -->li = 684(Ne cm ?3)?1/2 to outer scale -->lo = 106li, and (2) -->? = 3 (flat spectrum), --> = 0.02, and scale heights ranging from 50 to 75 km. We consider the fluctuations to be anisotropic with axial ratios of ~10. The Kolmogorov type of fluctuations yield slightly lower brightness temperatures in comparison with those of a flat spectrum. The brightness temperature distributions, east-west diameters, and central brightness temperatures at various frequencies indicate that the refraction and scattering are probably the underlying reasons for the unusual behavior of the quiet-Sun radio emission. This study clearly demonstrates that Monte Carlo techniques can be very effective in extracting the coronal electron temperatures accurately from the radio data, provided the information about the density distributions and density fluctuations is known by some independent methods.

G. Thejappa; R. J. MacDowall

2008-01-01T23:59:59.000Z

220

Focused excimer laser initiated, radio frequency sustained high pressure air plasmas  

SciTech Connect (OSTI)

Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (n{sub e} {approx} 7 x 10{sup 16}/cm{sup 3}) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm{sup 2} at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

Giar, Ryan; Scharer, John [Department of Electrical Engineering, University of Wisconsin-Madison, 506 Engineering Research Building, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)

2011-11-15T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Deposition of vertically oriented carbon nanofibers in atmospheric pressure radio frequency discharge  

SciTech Connect (OSTI)

Deposition of vertically oriented carbon nanofibers (CNFs) has been studied in an atmospheric pressure radio frequency discharge without dielectric barrier covering the metallic electrodes. When the frequency is sufficiently high so that ions reside in the gap for more than one rf cycle ('trapped ions'), the operating voltage decreases remarkably and the transition from a uniform glow discharge to an arc discharge is suppressed even without dielectric barriers. More importantly, the trapped ions are able to build up a cathodic ion sheath. A large potential drop is created in the sheath between the bulk plasma and the electrode, which is essential for aligning growing CNFs. At the same time, the damage to CNFs due to ion bombardment can be minimized at atmospheric pressure. The primary interest of the present work is in identifying the cathodic ion sheath and investigating how it influences the alignment of growing CNFs in atmospheric pressure plasma-enhanced chemical-vapor deposition. Spectral emission profiles of He (706 nm), H{alpha} (656 nm), and CH (432 nm) clearly showed that a dark space is formed between the cathode layer and the heated bottom electrode. However, increasing the rf power induced the transition to a nonuniform {gamma}-mode discharge which creates intense plasma spots in the dark space. Aligned CNFs can be grown at moderate input power during the initial stage of the deposition process. Catalyst particles were heavily contaminated by precipitated carbon in less than 5 min. Alignment deteriorates as CNFs grow and deposition was virtually terminated by the deactivation of catalyst particles.

Nozaki, Tomohiro; Goto, Tomoya; Okazaki, Ken; Ohnishi, Kuma; Mangolini, Lorenzo; Heberlein, Joachim; Kortshagen, Uwe [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro Tokyo 1528552 (Japan); Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2006-01-15T23:59:59.000Z

222

Loading and Regeneration Analysis of a Diesel Particulate Filter with a Radio Frequency-Based Sensor  

SciTech Connect (OSTI)

Accurate knowledge of diesel particulate filter (DPF) loading is critical for robust and efficient operation of the combined engine-exhaust aftertreatment system. Furthermore, upcoming on-board diagnostics regulations require on-board technologies to evaluate the status of the DPF. This work describes the application of radio frequency (RF) based sensing techniques to accurately measure DPF soot levels and the spatial distribution of the accumulated material. A 1.9L GM turbo diesel engine and a DPF with an RF-sensor were studied. Direct comparisons between the RF measurement and conventional pressure-based methods were made. Further analysis of the particulate matter loading rates was obtained with a mass-based soot emission measurement instrument (TEOM). Comparison with pressure drop measurements show the RF technique is unaffected by exhaust flow variations and exhibits a high degree of sensitivity to DPF soot loading and good dynamic response. Additional computational and experimental work further illustrates the spatial resolution of the RF measurements. Based on the experimental results, the RF technique shows significant promise for improving DPF control enabling optimization of the combined engine-aftertreatment system for improved fuel economy and extended DPF service life.

Sappok, Alex [Filter Sensing Technologies] [Filter Sensing Technologies; Prikhodko, Vitaly Y [ORNL] [ORNL; Parks, II, James E [ORNL

2010-01-01T23:59:59.000Z

223

RADIO FREQUENCY IDENTIFICATION DEVICES: EFFECTIVENESS IN IMPROVING SAFEGUARDS AT GAS-CENTRIFUGE URANIUM-ENRICHMENT PLANTS.  

SciTech Connect (OSTI)

Recent advances in radio frequency identification devices (RFIDs) have engendered a growing interest among international safeguards experts. Potentially, RFIDs could reduce inspection work, viz. the number of inspections, number of samples, and duration of the visits, and thus improve the efficiency and effectiveness of international safeguards. This study systematically examined the applications of RFIDs for IAEA safeguards at large gas-centrifuge enrichment plants (GCEPs). These analyses are expected to help identify the requirements and desirable properties for RFIDs, to provide insights into which vulnerabilities matter most, and help formulate the required assurance tests. This work, specifically assesses the application of RFIDs for the ''Option 4'' safeguards approach, proposed by Bruce Moran, U. S. Nuclear Regulatory Commission (NRC), for large gas-centrifuge uranium-enrichment plants. The features of ''Option 4'' safeguards include placing RFIDs on all feed, product and tails (F/P/T) cylinders, along with WID readers in all FP/T stations and accountability scales. Other features of Moran's ''Option 4'' are Mailbox declarations, monitoring of load-cell-based weighing systems at the F/P/T stations and accountability scales, and continuous enrichment monitors. Relevant diversion paths were explored to evaluate how RFIDs improve the efficiency and effectiveness of safeguards. Additionally, the analysis addresses the use of RFIDs in conjunction with video monitoring and neutron detectors in a perimeter-monitoring approach to show that RFIDs can help to detect unidentified cylinders.

JOE,J.

2007-07-08T23:59:59.000Z

224

In-Born Radio Frequency Identification Devices for Safeguards Use at Gas-Centrifuge Enrichment Plants  

SciTech Connect (OSTI)

Global expansion of nuclear power has made the need for improved safeguards measures at Gas Centrifuge Enrichment Plants (GCEPs) imperative. One technology under consideration for safeguards applications is Radio Frequency Identification Devices (RFIDs). RFIDs have the potential to increase IAEA inspector"s efficiency and effectiveness either by reducing the number of inspection visits necessary or by reducing inspection effort at those visits. This study assesses the use of RFIDs as an integral component of the "Option 4" safeguards approach developed by Bruce Moran, U.S. Nuclear Regulatory Commission (NRC), for a model GCEP [1]. A previous analysis of RFIDs was conducted by Jae Jo, Brookhaven National Laboratory (BNL), which evaluated the effectiveness of an RFID tag applied by the facility operator [2]. This paper presents a similar evaluation carried out in the framework of Jo’s paper, but it is predicated on the assumption that the RFID tag is applied by the manufacturer at the birth of the cylinder, rather than by the operator. Relevant diversion scenarios are examined to determine if RFIDs increase the effectiveness and/ or efficiency of safeguards in these scenarios. Conclusions on the benefits offered to inspectors by using in-born RFID tagging are presented.

Ward,R.; Rosenthal,M.

2009-07-12T23:59:59.000Z

225

Instabilities and multiple steady states of radio-frequency discharges in CF4  

Science Journals Connector (OSTI)

A one-dimensional fluid model coupled with solution tracking algorithms was applied for an L=5 mm CF4 (radio frequency) rf discharge at P=2 Torr (low PL value of PL=1). The discharge exhibited a rich behavior of solution multiplicity as a function of applied rf current density (or voltage). The most prominent characteristic was the development of dc self-bias and asymmetry under completely symmetric discharge conditions, in agreement with experimental data by J. Butterbaugh (Ph.D. dissertation, Massachusetts Institute of Technology, 1990). The plasma can exist in three states of positive, negative, and zero self-bias, of which the first two are asymmetric and stable, while the third is symmetric and unstable. The two asymmetric solutions collapse again into one symmetric solution with zero self-bias at a higher voltage, a transition which depends on the value of the secondary electron emission coefficient. At lower applied currents (or voltages) the hysterisis loop of this electronegative plasma is presented between breakdown and extinction, and an unstable plasma is found between the two points. The observed phenomena are related to the transition of the discharge from diffusion-controlled to electron-oscillation-amplitude-controlled breakdowns. The sustaining mechanisms of the plasma and the electron dynamics are discussed. © 1996 The American Physical Society.

Efimia Metsi; Evangelos Gogolides; Andreas Boudouvis

1996-07-01T23:59:59.000Z

226

Production of oxygen plasmas using radio-frequency magnetron-discharge  

Science Journals Connector (OSTI)

A new type of oxygen ion source has been developed in order to substantially prolong the lifetime of a conventional oxygen ion source for various plasma processes. In this ion source, an oxygen plasma is produced by coupling a 13.56 \\{MHz\\} radio-frequency (rf) field to a pair of rf electrodes placed in the region of a line cusp field. Two electrodes are positioned in such a way that accelerated electrons undergo magnetron type motion around them, efficiently producing a plasma around the electrodes (rf magnetron discharge). This plasma diffuses along the magnetic field line into the center region of the cusp field where the field strength is almost nil. The above process makes it possible to produce a large volume of uniform plasma. As a result, extraction of a large area oxygen-ion-beam from the new ion source is relatively easy. The lifetime of this ion source is virtually limitless, because it does not have any corrosive parts, such as a hot filament. The new ion source can be used with any kind of reactive gases as well as oxygen.

Takehisa Shibuya; Shizuyo Hashimoto; Eiji Yabe; Kazuo Takayama

1991-01-01T23:59:59.000Z

227

Method of making radio frequency ion source antenna and such antenna  

DOE Patents [OSTI]

In the method, the radio frequency (rf) antenna is made by providing a clean coil made of copper tubing or other metal conductor, which is coated with a tacky organic binder, and then with a powdered glass frit, as by sprinkling the frit uniformly over the binder. The coil is then heated internally in an inert gas atmosphere, preferably by passing an electrical heating current along the coil. Initially, the coil is internally heated to about 200/sup 0/C to boil off the water from the binder, and then to about 750 to 850/sup 0/C to melt the glass frit, while also burning off the organic binder. The melted frit forms a molten glass coating on the metal coil, which is then cooled to solidify the glass, so that the metal coil is covered with a thin continuous homogeneous impervious glass coating of substantially uniform thickness. The glass coating affords complete electrical insulation and complete dielectric protection for the metal coil of the rf antenna, to withstand voltage breakdown and to prevent sputtering, while also doubling the plasma generating efficiency of the rf antenna, when energized with RF power in the vacuum chamber of an ion source for a particle accelerator or the like. The glass frit preferably contains approximately 45% lead oxide.

Ehlers, K.W.; Leung, K.N.

1985-05-22T23:59:59.000Z

228

Control of radio-frequency atmospheric pressure argon plasma characteristics by helium gas mixing  

SciTech Connect (OSTI)

The control of plasma characteristics is one of the important issues in many atmospheric pressure plasma applications. In order to accomplish this control, a feasibility study was performed by investigating the role of helium gas in an argon glow plasma that were produced in ambient air by 13.56 MHz radio-frequency power. Optical emission spectroscopy was used to measure rotational temperature and emission spectra acquired between 300 and 840 nm. Based on electrical and optical measurements, parameters such as gas temperature, breakdown voltage, power coupling efficiency, spatial uniformity of rotational temperature, and the sum of the emission intensity were controlled by varying the argon and helium gas mixing ratio. The addition of helium gas (from 0 to 10 lpm) to the argon flow (of 10 lpm) lowered the breakdown voltage (from 430 to 300 V{sub pk}) and the rotational temperature (from 465 to 360 K). However, an excessive addition of helium resulted in a reduction of the spatial uniformity and efficiency of power coupling. When the ratio of helium to argon flow was between 0.3 and 0.5, a high spatial uniformity with a relatively low gas temperature and breakdown voltage was achieved. This suggests that mixing of the supply gas is a useful way of controlling the plasma characteristics that may be utilized for applications with specific required discharge conditions.

Moon, Se Youn; Han, Jewoo; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2006-01-15T23:59:59.000Z

229

Results from sudden loss of vacuum on scaled superconducting radio frequency cryomodule experiment  

SciTech Connect (OSTI)

Superconducting radio frequency (SRF) cavities for particle accelerators are at risk of failure due to sudden loss of vacuum (SLV) adjacent to liquid helium (LHe) spaces. To better understand this failure mode and its associated risks an experiment is designed to test the longitudinal effects of SLV within the beam tube of a scaled SRF cryomodule that has considerable length relative to beam tube cross section. The scaled cryomodule consists of six individual SRF cavities each roughly 350 mm long, initially cooled to 2 K by a superfluid helium bath and a beam tube pumped to vacuum. A fast-acting solenoid valve is used to simulate SLV on the beam tube, from which point it takes over 3 s for the beam tube pressure to equalize with atmosphere, and 30 s for the helium space to reach the relief pressure of 4 bara. A SLV longitudinal effect in the beam tube is evident in both pressure and temperature data, but interestingly the temperatures responds more quickly to SLV than do the pressures. It takes 500 ms (roughly 100 ms per cavity) for the far end of the 2 m long beam tube to respond to a pressure increase compared to 300 ms for temperature (approximately 50 ms per cavity). The paper expands upon these and other results to better understand the longitudinal effect for SRF cryomodules due to SLV.

Dalesandro, Andrew A.; Theilacker, Jay C. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Dhuley, Ram C.; Van Sciver, Steven W. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States)

2014-01-29T23:59:59.000Z

230

Development of Ultra High Gradient and High Q{sub 0} Superconducting Radio Frequency Cavities  

SciTech Connect (OSTI)

We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q{sub 0} superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q{sub 0} of 10{sup 10} at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q{sub 0} of 2?10{sup 10} at 2K.

Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Clemens, William A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Follkie, James E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Harris, Teena M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Kushnick, Peter W. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Machie, Danny [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Martin, Robert E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Palczewski, Ari D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Perry, Era A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Slack, Gary L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Williams, R. S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Adolphsen, C. [SLAC, Menlo Park, California, (United States); Li, Z. [SLAC, Menlo Park, California, (United States); Hao, J. K. [Peking University, Beijing (China); Li, Y. M. [Peking University, Beijing (China); Liu, K. X. [Peking University, Beijing (China)

2013-06-01T23:59:59.000Z

231

First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities  

SciTech Connect (OSTI)

Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

2013-09-01T23:59:59.000Z

232

Topographic power spectral density study of the effect of surface treatment processes on niobium for superconducting radio frequency accelerator cavities  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

Microroughness is viewed as a critical issue for attaining optimum performance of superconducting radio frequency accelerator cavities. The principal surface smoothing methods are buffered chemical polish (BCP) and electropolish (EP). The resulting topography is characterized by atomic force microscopy (AFM). The power spectral density (PSD) of AFM data provides a more thorough description of the topography than a single-value roughness measurement. In this work, one dimensional average PSD functions derived from topography of BCP and EP with different controlled starting conditions and durations have been fitted with a combination of power law, K correlation, and shifted Gaussian models to extract characteristic parameters at different spatial harmonic scales. While the simplest characterizations of these data are not new, the systematic tracking of scale-specific roughness as a function of processing is new and offers feedback for tighter process prescriptions more knowledgably targeted at beneficial niobium topography for superconducting radio frequency applications.

Xu, Chen; Tian, Hui; Reece, Charles E.; Kelley, Michael J.

2012-04-01T23:59:59.000Z

233

H{sup -} beam extraction from a cesium seeded field effect transistor based radio frequency negative hydrogen ion source  

SciTech Connect (OSTI)

H{sup -} beam was successfully extracted from a cesium seeded ion source operated using a field effect transistor inverter power supply as a radio frequency (RF) wave source. High density hydrogen plasma more than 10{sup 19} m{sup -3} was obtained using an external type antenna with RF frequency of lower than 0.5 MHz. The source was isolated by an isolation transformer and H{sup -} ion beam was extracted from a single aperture. Acceleration current and extraction current increased with the increase of extraction voltage. Addition of a small amount of cesium vapor into the source enhanced the currents.

Ando, A.; Matsuno, T.; Funaoi, T.; Tanaka, N. [School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Tsumori, K.; Takeiri, Y. [National Institute for Fusion Science, Toki 509-5292 (Japan)

2012-02-15T23:59:59.000Z

234

H{sup -} radio frequency source development at the Spallation Neutron Source  

SciTech Connect (OSTI)

The Spallation Neutron Source (SNS) now routinely operates nearly 1 MW of beam power on target with a highly persistent {approx}38 mA peak current in the linac and an availability of {approx}90%. H{sup -} beam pulses ({approx}1 ms, 60 Hz) are produced by a Cs-enhanced, multicusp ion source closely coupled with an electrostatic low energy beam transport (LEBT), which focuses the 65 kV beam into a radio frequency quadrupole accelerator. The source plasma is generated by RF excitation (2 MHz, {approx}60 kW) of a copper antenna that has been encased with a thickness of {approx}0.7 mm of porcelain enamel and immersed into the plasma chamber. The ion source and LEBT normally have a combined availability of {approx}99%. Recent increases in duty-factor and RF power have made antenna failures a leading cause of downtime. This report first identifies the physical mechanism of antenna failure from a statistical inspection of {approx}75 antennas which ran at the SNS, scanning electron microscopy studies of antenna surface, and cross sectional cuts and analysis of calorimetric heating measurements. Failure mitigation efforts are then described which include modifying the antenna geometry and our acceptance/installation criteria. Progress and status of the development of the SNS external antenna source, a long-term solution to the internal antenna problem, are then discussed. Currently, this source is capable of delivering comparable beam currents to the baseline source to the SNS and, an earlier version, has briefly demonstrated unanalyzed currents up to {approx}100 mA (1 ms, 60 Hz) on the test stand. In particular, this paper discusses plasma ignition (dc and RF plasma guns), antenna reliability, magnet overheating, and insufficient beam persistence.

Welton, R. F.; Gawne, K. R.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Roseberry, R. T.; Santana, M.; Stockli, M. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37830-6471 (United States); Dudnikov, V. G. [Muons, Inc., 552 N. Batavia Avenue, Batavia, Illinois 60510 (United States); Turvey, M. W. [Villanova University, 800E. Lancaster Ave, Villanova, Pennsylvania 19085 (United States)

2012-02-15T23:59:59.000Z

235

Harmonic filters influences regarding the power quality on high frequency electrothermal installation with electromagnetic induction  

Science Journals Connector (OSTI)

This paper presents a study regarding the functioning of a melting/hardening electrothermal installation with electromagnetic induction from the point of view of generated harmonics in the power distribution. The authors made simulations in scope of ... Keywords: electrothermal installation, harmonic, passive filters, static converter

Raluca Rob; Ioan Sora; Caius Panoiu; Manuela Panoiu

2010-01-01T23:59:59.000Z

236

HIGH-FREQUENCY RADIO SPECTRAL ENERGY DISTRIBUTIONS AND POLARIZATION FRACTIONS OF SOURCES IN AN ATACAMA COSMOLOGY TELESCOPE SURVEY FIELD  

SciTech Connect (OSTI)

We present flux densities and polarization percentages of 159 radio galaxies based on nearly simultaneous Very Large Array observations at four frequencies, 4.86, 8.46, 22.46, and 43.34 GHz. This sample is selected from the high-frequency Australia Telescope 20 GHz (AT20G) survey and consists of all sources with flux density S{sub 20GHz} > 40 mJy in an equatorial field of the Atacama Cosmology Telescope (ACT) survey. For a subset of 25 of these sources, we used the Green Bank Telescope (GBT) to obtain 90 GHz data. The goals of this program are: (1) a characterization of the spectra, polarization, and variability of high-frequency-selected radio sources, (2) extrapolating from the few GHz regime to the {approx}150 GHz regime of the ACT survey, allowing for more accurate removal of the radio source signal in our particular field, and (3) providing a data set that will allow more accurate modeling of the high-frequency radio source contamination in current and future Sunyaev-Zeldovich and cosmic microwave background experiments. We find that, as expected, this sample consists of flatter spectrum and more compact or point-like sources than low-frequency-selected samples. In the K band, variability is typically {approx}<20%, although there are exceptions. The higher frequency data are well suited to the detection of extreme gigahertz peak spectrum sources. The inclusion of the 43 GHz data causes the relative fraction of inverted spectrum sources to go down and of peaked spectrum sources to go up when compared with the AT20G survey results. The trend largely continues with the inclusion of the 90 GHz data, although {approx}10% of the sources with GBT data show a spectral upturn from 43 GHz to 90 GHz. The measured polarization fractions are typically <5%, although in some cases they are measured to be up to {approx}20%. For sources with detected polarized flux in all four bands, about 40% of the sample, the polarization fractions typically increase with frequency. This trend is stronger for steeper spectrum sources as well as for the lower flux density sources.

Sajina, Anna [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Partridge, Bruce; Evans, Tyler; Vechik, Nicholas [Department of Physics and Astronomy, Haverford College, Haverford, PA 19041 (United States); Stefl, Shannon [Kent State University, Kent, OH 44242 (United States); Myers, Steve [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Dicker, Simon; Korngut, Phillip [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)

2011-05-01T23:59:59.000Z

237

One-Dimensional Modeling on the Asymmetric Features of a Radio-Frequency Atmospheric Helium Glow Discharge Produced Using a Co-Axial-Type Plasma Generator  

Science Journals Connector (OSTI)

As one type of the atmospheric glow discharges, the radio-frequency atmospheric-pressure glow discharges produced using the water-cooled bare-metallic electrode, which are the...1–3...]. The capacitively-coupled ...

Zhi-Bin Wang; Pei-Si Le; Nan Ge; Qiu-Yue Nie…

2012-08-01T23:59:59.000Z

238

A high frequency radio study of G11.2-0.3, a historical supernova remnant with a flat spectrum core  

E-Print Network [OSTI]

We present radio maps of the historical supernova remnant G11.2-0.3 in the frequency range from 4.85 GHz to 32 GHz. The integrated spectrum with \\alpha = -0.50 (S ~ \

R. Kothes; W. Reich

2001-04-24T23:59:59.000Z

239

Heating of Plasma Ions in a Tokamak by the Second-Harmonic Ion-Cyclotron Resonance Interaction with Radio-Frequency Waves  

Science Journals Connector (OSTI)

The radio-frequency-wave heating of ions in a tokamak plasma employing the second-harmonic ion-cyclotron resonance interaction has been demonstrated in recent high-power (3-MW) experiments on the Princeton Large Torus tokamak.

D. Q. Hwang; J. Hosea; H. Thompson; J. R. Wilson; S. Davis; D. Herndon; R. Kaita; D. Mueller; S. Suckewer; C. Daughney; P. Colestock

1983-11-14T23:59:59.000Z

240

Room-temperature high radio-frequency source power effects on silicon nitride films deposited by using a plasma-enhanced chemical vapor deposition  

Science Journals Connector (OSTI)

Silicon nitride films were deposited at room temperature using a plasma-enhanced chemical vapor deposition system. In this study, the effects of radio frequency (RF) source power ranging from 200 W to ... charact...

Byungwhan Kim; Suyeon Kim

2008-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Slow Radio-Frequency Processing of Large Oil Shale Volumes to Produce Petroleum-Like Shale Oil  

SciTech Connect (OSTI)

A process is proposed to convert oil shale by radio frequency heating over a period of months to years to create a product similar to natural petroleum. Electrodes would be placed in drill holes, either vertical or horizontal, and a radio frequency chosen so that the penetration depth of the radio waves is of the order of tens to hundreds of meters. A combination of excess volume production and overburden compaction drives the oil and gas from the shale into the drill holes, where it is pumped to the surface. Electrical energy for the process could be provided initially by excess regional capacity, especially off-peak power, which would generate {approx}3 x 10{sup 5} bbl/day of synthetic crude oil, depending on shale grade. The electricity cost, using conservative efficiency assumptions, is $4.70 to $6.30/bbl, depending on grade and heating rate. At steady state, co-produced gas can generate more than half the electric power needed for the process, with the fraction depending on oil shale grade. This would increase production to 7.3 x 10{sup 5} bbl/day for 104 l/Mg shale and 1.6 x 10{sup 6} bbl/day for 146 l/Mg shale using a combination of off-peak power and power from co-produced gas.

Burnham, A K

2003-08-20T23:59:59.000Z

242

Electromagnetic Heating Methods for Heavy Oil Reservoirs  

SciTech Connect (OSTI)

The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.

Sahni, A.; Kumar, M.; Knapp, R.B.

2000-05-01T23:59:59.000Z

243

VERY LONG BASELINE ARRAY MULTI-FREQUENCY POLARIMETRIC IMAGING OF RADIO-LOUD BROAD ABSORPTION LINE QUASARS  

SciTech Connect (OSTI)

We conducted the first multi-frequency polarimetric imaging of four broad absorption line (BAL) quasars using the Very Long Baseline Array at milliarcsecond resolutions to investigate the inclination of the nonthermal jet and test the hypothesis that radio sources in BAL quasars are still young. Among these four sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in parsec scales and polarized emission detected in the core. These characteristics are consistent with those of blazars. We set constraints on viewing angles to <66 Degree-Sign for these jets in the framework of a Doppler beaming effect. J1159+0112 exhibits an unpolarized gigahertz-peaked spectrum component and several discrete blobs with steep spectra on both sides of the central component across {approx}1 kpc. These properties are consistent with those of young radio sources. We discuss the structures of jets and active galactic nucleus wind.

Hayashi, Takayuki J.; Nagai, Hiroshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan); Doi, Akihiro, E-mail: t.hayashi@nao.ac.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa, 252-5210 (Japan)

2013-07-20T23:59:59.000Z

244

Radio-frequency identification could help reduce the spread of plant pathogens  

E-Print Network [OSTI]

frequency identification could help reduce the spread ofeconomic losses. It also helps control the Plant Protection

Luvisi, Andrea; Panattoni, Alessandra; Triolo, Enrico

2012-01-01T23:59:59.000Z

245

Comparative study of laminar and turbulent flow model with different operating parameters for radio frequency-inductively coupled plasma torch working at 3??MHz frequency at atmospheric pressure  

Science Journals Connector (OSTI)

This paper provides 2D comparative study of results obtained using laminar and turbulent flow model for RF (radio frequency) Inductively Coupled Plasma (ICP) torch. The study was done for the RF-ICP torch operating at 50?kW DC power and 3?MHz frequency located at BARC. The numerical modeling for this RF-ICP torch is done using ANSYS software with the developed User Defined Function. A comparative study is done between laminar and turbulent flow model to investigate how temperature and flow fields change when using different operating conditions such as (a) swirl and no swirl velocity for sheath gas flow rate (b) variation in sheath gas flow rate and (c) variation in plasma gas flow rate. These studies will be useful for different material processing applications.

Sangeeta B. Punjabi; S. N. Sahasrabudhe; N. K. Joshi; H. A. Mangalvedekar; A. K. Das; D. C. Kothari

2014-01-01T23:59:59.000Z

246

Effect of Cyclotron Resonance Frequencies in Particles Due to AC and DC Electromagnetic Fields  

E-Print Network [OSTI]

and Environmental Engineering, The University of Melbourne, VIC 3010, Australia Department of Electrical and Electronic Engineering, University of Peradeniya, Peradeniya, Srilanka Email: malka and ion cyclotron resonance (ICR) frequencies which is derived from ionic charge to mass ratio is evident

Halgamuge, Malka N.

247

Low-Frequency Electromagnetic Response Function for Strong-Coupling Superconductors  

E-Print Network [OSTI]

properties of superconduc- tors is well known. For example, the frequency dependence of the electrical conductivity in strong- coupling superconductors has been observed by both infrared" and microwave' techniques. Also, the magnitude and temperature... dependence of the low-frequency conductivity for Pb have been in- ferred from measurements of magnetic field at- tenuation, ' while kinetic inductance' measure- ments have been used to study this temperature dependence for amorphous superconductors...

SCHOLTEN, PD; LEJEUNE, JD; SASLOW, WM; Naugle, Donald G.

1977-01-01T23:59:59.000Z

248

Radio frequency dc-dc converters : device characterization, topology evaluation, and design  

E-Print Network [OSTI]

High frequency power conversion is attractive for the opportunities it affords for improved performance. Dc-dc converters operating at high frequencies use smaller-valued energy storage elements, which tend to be physically ...

Leitermann, Olivia

2008-01-01T23:59:59.000Z

249

Comparative Study of Frequency Agile Data Transmission Schemes for Cognitive Radio Transceivers  

E-Print Network [OSTI]

agile data transmission schemes employed by cognitive radio transceivers for use in dynamic spectrum for this apparent spectrum scarcity. Although, measurement studies have shown that licensed spectrum is relatively- This work was supported by NSF grants ANI-0230786 and ANI- 0335272. licensed users "borrowing" spectrum from

Kansas, University of

250

Limits on low-frequency radio emission from southern exoplanets with the Murchison Widefield Array  

Science Journals Connector (OSTI)

......Zealand 16 Department of Atmospheric, Oceanic and Space Sciences...radio emission at 154-MHz, and put 3sigma upper...would give a limit on the plasma density in the magnetosphere...VLA) at 333 and 1400-MHz, but made no detections...VLA at 333 and 1465-MHz and one at 74-MHz......

Tara Murphy; Martin E. Bell; David L. Kaplan; B. M. Gaensler; André R. Offringa; Emil Lenc; Natasha Hurley-Walker; G. Bernardi; J. D. Bowman; F. Briggs; R. J. Cappallo; B. E. Corey; A. A. Deshpande; D. Emrich; R. Goeke; L. J. Greenhill; B. J. Hazelton; J. N. Hewitt; M. Johnston-Hollitt; J. C. Kasper; E. Kratzenberg; C. J. Lonsdale; M. J. Lynch; S. R. McWhirter; D. A. Mitchell; M. F. Morales; E. Morgan; D. Oberoi; S. M. Ord; T. Prabu; A. E. E. Rogers; D. A. Roshi; N. Udaya Shankar; K. S. Srivani; R. Subrahmanyan; S. J. Tingay; M. Waterson; R. B. Wayth; R. L. Webster; A. R. Whitney; A. Williams; C. L. Williams

2015-01-01T23:59:59.000Z

251

Utilization of electromagnetic detector for selection and detection of high-frequency relic gravitational waves  

E-Print Network [OSTI]

It is shown that coupling system between fractal membranes and a Gaussian beam passing through a static magnetic field has strong selection capability for the stochastic relic gravitational wave background. The relic GW components propagating along the positive direction of the symmetrical axis of the Gaussian beam might generate an optimal electromagnetic perturbation while the perturbation produced by the relic GW components propagating along the negative and perpendicular directions to the symmetrical axis will be much less than the former.The influence of the random fluctuation of the relic GWs to such effect can be neglected and the influence of the random fluctuation of the relic GWs to such effect can be neglected.

Fangyu Li; Zhenya Chen; Ying Yi

2005-11-03T23:59:59.000Z

252

Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma  

SciTech Connect (OSTI)

Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

Janardan Upadhyay, Larry Phillips, Anne-Marie Valente

2011-09-01T23:59:59.000Z

253

Radio-frequency measurements of UNiX compounds (X= Al, Ga, Ge) in high magnetic fields  

SciTech Connect (OSTI)

We performed radio-frequency (RF) skin-depth measurements of antiferromagnetic UNiX compounds (X=Al, Ga, Ge) in magnetic fields up to 60 T and at temperatures between 1.4 to {approx}60 K. Magnetic fields are applied along different crystallographic directions and RF penetration-depth was measured using a tunnel-diode oscillator (TDO) circuit. The sample is coupled to the inductive element of a TDO resonant tank circuit, and the shift in the resonant frequency {Delta}f of the circuit is measured. The UNiX compounds exhibit field-induced magnetic transitions at low temperatures, and those transitions are accompanied by a drastic change in {Delta}f. The results of our skin-depth measurements were compared with previously published B-T phase diagrams for these three compounds.

Mielke, Charles H [Los Alamos National Laboratory; Mcdonald, David R [Los Alamos National Laboratory; Zapf, Vivien [Los Alamos National Laboratory; Altarawneh, Moaz M [Los Alamos National Laboratory; Lacerda, Alex H [Los Alamos National Laboratory; Adak, Sourav [Los Alamos National Laboratory; Karunakar, Kothapalli [Los Alamos National Laboratory; Nakotte, Heinrich [Los Alamos National Laboratory; Chang, S [NIST; Alsmadi, A M [HASHEMITE UNIV; Alyones, S [HASHEMIT UNIV

2009-01-01T23:59:59.000Z

254

High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.  

SciTech Connect (OSTI)

Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch train with a bunch spacing of 769ps and bunch charges of 50nC each, 90.4MW and 8.68MW of extracted power levels are expected to be reached at 20.8GHz and 35.1GHz, respectively. In order to improve efficiency in HOM power extraction, a novel technique has been proposed to suppress unintended modes.

Gao, F.; High Energy Physics; Illinois Inst. of Tech

2009-07-24T23:59:59.000Z

255

Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies  

SciTech Connect (OSTI)

Quasi-simultaneous observations of the BL Lac object Mrk 501 were performed for the first time at X-ray, ultraviolet, visible infrared, and radio frequencies. As the BL Lac objects are known to vary in their flux, such a ''quasi-instantaneous'' spectral energy profile is necessary in order to describe properly the energy generation mechanism. The observed spectral slope from the X-ray to UV regions is positive and continuous, but that from the mid-UV to visible light region becomes gradually flat and possibly turns down toward lower frequencies; the optical-radio emission cannot be accounted for by a single power law. Several theoretical models have been considered for the emission mechanism. In some cases quantitative comparison with the data is not practical. However, most of the models are, at least, not inconsistent with the observations. A quantitative comparison has been peformed with the synchroton self-Compton model; the total spectrum is found consistent with this model. The spectrum from visible light to X-ray is consistent with synchrotron radiation or with inverse-Compton scattering by a hot thermal cloud of electrons. The continuity of the spectral slope from X-ray to UV implied by the current data suggests that the previous estimates of the total luminosity of this BL Lac object has been underestimated by a factor of about 3 or 4.

Kondo, Y.; Worrall, D.M.; Mushotzky, R.F.; Hackney, R.L.; Hackney, K.R.H.; Oke, J.B.; Yee, H.K.C.; Neugebauer, G.; Matthews, K.; Feldman, P.A.; Brown, R.L.

1981-02-01T23:59:59.000Z

256

Through-Barrier Electromagnetic Communication and Sensing: Advances in  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Through-Barrier Electromagnetic Communication and Sensing: Advances in Through-Barrier Electromagnetic Communication and Sensing: Advances in Wideband Radio-Wave Communications and ..... Speaker(s): Farid Dowla Date: June 1, 2007 - 12:00pm Location: 90-3122 Seminar Host/Point of Contact: Mary Ann Piette (Complete seminar title is: Through-Barrier Electromagnetic Communication and Sensing: Advances in Wideband Radio-Wave Communications and Radar Imaging, Radio-Frequency (RF) Tags and Tera-Hertz (THz) Standoff Detection Spectroscopy) In many remote sensing problems there is a critical need to detect and image objects through barriers, such as buildings, with high reliability and resolution and at long ranges. A related problem is the wireless communication and geolocation of transceivers in harsh RF environments, such as in urban areas and underground caves, where

257

GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, Detecting nanoparticles at radio frequencies: Jovian  

E-Print Network [OSTI]

T December 26, 2008, 4:59pm D R A F T #12;X - 2 MEYER-VERNET ET AL.: DETECTING NANOPARTICLES AT RADIO with a conventional detection by a dust analyser attributed to nanoparticles. D R A F T December 26, 2008, 4:59pm D R dust detectors: first it has a D R A F T December 26, 2008, 4:59pm D R A F T #12;X - 4 MEYER-VERNET ET

Demoulin, Pascal

258

Radio-Frequency Interference (RFI) From Extra-High-Voltage (EHV) Transmission Lines  

E-Print Network [OSTI]

discharges are a design issue. Extra-high-voltage (EHV) transmission lines have operating voltages of 345 kV building a 345-kV transmission line from Red Hill, NM to Deming, NM which would run east along US60 to its with respect to radio noise: (1) lines with voltages below 70 kV and (2) lines with voltages above 110 kV

Ellingson, Steven W.

259

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 1, JANUARY 2009 129 Very-Low-Frequency Electromagnetic Field  

E-Print Network [OSTI]

, Walter J. Varhue, and Stephen Titcomb, Senior Member, IEEE Abstract--Naturally occurring electromagnetic and difficult to detect under normal conditions. These naturally occurring VLF electromagnetic events. This electronic system can be used to monitor VLF electromagnetic radiation in residential and occupational

Motai, Yuichi

260

Probing the Climatological Impact of a Cosmic Ray-Cloud Connection through Low-Frequency Radio Observations  

E-Print Network [OSTI]

It has been proposed that cosmic ray events could have a causal relationship with cloud formation rates. Given the weak constraints on the role that cloud formation plays in climate forcing it is essential to understand the role such a relationship could have in shaping the Earth's climate. This issue has been previously investigated in the context of the long-term effect of cosmic ray events on climate. However, in order to establish whether or not such a relationship exists, measurements of short-timescale solar events, individual cosmic ray events, and spatially correlated cloud parameters could be of great significance. Here we propose such a comparison using observations from a pair of radio telescopes arrays, the Long Wavelength Array (LWA) and the Eight-meter-wavelength Transient Array (ETA). These low-frequency radio arrays have a unique ability to simultaneously conduct solar, ionospheric and cosmic rays observations and are thus ideal for such a comparison. We will outline plans for a comparison usi...

Magee, Nathan

2011-01-01T23:59:59.000Z

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261

A HIGH-FREQUENCY TYPE II SOLAR RADIO BURST ASSOCIATED WITH THE 2011 FEBRUARY 13 CORONAL MASS EJECTION  

SciTech Connect (OSTI)

We examine the relationship between the high-frequency (425 MHz) type II radio burst and the associated white-light coronal mass ejection (CME) that occurred on 2011 February 13. The radio burst had a drift rate of 2.5 MHz s{sup -1}, indicating a relatively high shock speed. From SDO/AIA observations we find that a loop-like erupting front sweeps across high-density coronal loops near the start time of the burst (17:34:17 UT). The deduced distance of shock formation (0.06 Rs) from the flare center and speed of the shock (1100 km s{sup -1}) using the measured density from SDO/AIA observations are comparable to the height (0.05 Rs, from the solar surface) and speed (700 km s{sup -1}) of the CME leading edge observed by STEREO/EUVI. We conclude that the type II burst originates even in the low corona (<59 Mm or 0.08 Rs, above the solar surface) due to the fast CME shock passing through high-density loops.

Cho, K.-S.; Kim, R.-S. [Korea Astronomy and Space Science Institute, Whaamdong, Yooseong-ku, Daejeon, 305-348 (Korea, Republic of); Gopalswamy, N.; Kwon, R.-Y.; Yashiro, S., E-mail: kscho@kasi.re.kr [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-03-10T23:59:59.000Z

262

Advanced Heat Transfer Studies in Superfluid Helium for Large-scale High-yield Production of Superconducting Radio Frequency Cavities  

E-Print Network [OSTI]

Oscillating Superleak Transducers (OSTs) can be used to localize quenches in superconducting radio frequency cavities. In the presented work the occurring thermal effects during such events are investigated both theoretically and experimentally. In the theoretical part the entire heat transfer process from the heat generation to the detection is covered. The experimental part focuses on the effects in superfluid helium. Previous publications observed the detection of an OST signal that was faster than the second sound velocity. This fast propagation could be verified in dedicated small scale experiments. Resistors were used to simulate the quench spots under controlled conditions. The three dimensional propagation of second sound was linked to OST signals for the first time, which improves the understanding of the OST signal and allows to gather information about the heating pulse. Additionally, OSTs were used as a tool for quench localisation on a real size cavity. Their sensitivity as well as the time resol...

Peters, Benedikt J; Schirm, Karl-Martin; Koettig, Torsten

263

A METHOD TO EXTRACT THE ANGULAR POWER SPECTRUM OF THE EPOCH OF REIONIZATION FROM LOW-FREQUENCY RADIO INTERFEROMETERS  

SciTech Connect (OSTI)

The redshifted 21 cm signal of neutral hydrogen from the epoch of reionization (EoR) is extremely weak and its first detection is therefore expected to be statistical with first-generation low-frequency radio interferometers. In this Letter, we propose a method to extract the angular power spectrum of the EoR from the visibility correlation coefficients p{sub ij} (u, v), instead of the visibilities V{sub ij} (u, v) measured directly by radio interferometers in conventional algorithm. The visibility correlation coefficients are defined as p{sub ij}(u,v)=V{sub ij}(u,v)/{radical}(|V{sub ii}||V{sub jj}|) by introducing the autocorrelation terms V{sub ii} and V{sub jj} such that the angular power spectrum C{sub l} can be obtained through C{sub l} = T {sup 2}{sub 0}(|p{sub ij} (u, v)|{sup 2}), independently of the primary beams of antennas. This also partially removes the influence of receiver gains in the measurement of C{sub l} because the amplitudes of the gains cancel each other out in the statistical average operation of (|p{sub ij} (u, v)|{sup 2}). We use the average system temperature T{sub 0} as a calibrator of C{sub l}, which is dominated by the Milky Way and extragalactic sources in the frequency range that we are interested in, below 200 MHz. Finally, we demonstrate the feasibility of this novel method using the simulated sky maps as targets and the 21 CentiMeter Array (21CMA) as interferometer.

Zheng Qian; Wu Xiangping; Gu Junhua [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Wang Jingying; Xu Haiguang [Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

2012-10-10T23:59:59.000Z

264

Implementation of a Dual Containment/Surveillance System utilizing scene-change detection and radio frequency technology  

SciTech Connect (OSTI)

This paper will examine the implementation of scene-change detection and radio frequency technology within a Dual Containment/Surveillance (C/S) System. Additionally, this paper will examine the human performance factors in the operation of these systems. Currently, Westinghouse Savannah River Company utilizes the Continuous Item Monitoring and Surveillance System (CIMS) in the performance of Dual C/S to monitor special nuclear materials within International Atomic Energy Agency (IAEA) Safeguards and Domestic Safeguards. CIMS is comprised of the Material Monitoring System (MMS) (R), a multi-media electronic surveillance system developed by Sandia National Laboratory which incorporates the use of active seals commonly called Radio Frequency Tamper Indicating Devices (RFTIDs), NT Vision (R) as developed by Los Alamos National Laboratory, a Microsoft Windows NT (R) based operating system providing for domestic scene-change detection and the Digital Multi-Camera Optical Surveillance System (DMOS) (R) which provides scene-change detection for IAEA. Although this paper will focus on the implementation of Dual C/S utilizing the Continuous Item Monitoring and Surveillance System, the necessity for a thorough review of Safeguards and Security requirements with organizations and personnel having minimal to no prior MPC&A training will also be covered. Successful Dual C/S implementation plans must consider not only system design and failure modes, but must also be accompanied with the appropriate ''mind shift'' within operations and technical personnel. This is required to ensure completion of both physical and electronic activities, and system design changes are performed conscientiously and with full awareness of MPC&A requirements.

FITZGERALD, ERIC; KOENIG, RICHARD

2005-06-27T23:59:59.000Z

265

Gas breakdown in an atmospheric pressure radio-frequency capacitive plasma source  

Science Journals Connector (OSTI)

Gas breakdown is studied in an atmospheric pressure rf capacitive plasma source developed for materials applications. At a rf frequency of 13.56 MHz breakdown voltage is largely a function of the product of the pressure and the discharge gap spacing approximating the Paschen curve. However breakdown voltage varies substantially with rf frequency due to a change in the electron loss mechanism. A large increase in breakdown voltage is observed when argon oxygen or nitrogen is added to helium despite their lower ionization potential. Discussion is given for optimal breakdown conditions at atmospheric pressure.

Jaeyoung Park; I. Henins; H. W. Herrmann; G. S. Selwyn

2001-01-01T23:59:59.000Z

266

Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference  

DOE Patents [OSTI]

An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp.

Simpson, James E. (Gaithersburg, MD)

1999-01-01T23:59:59.000Z

267

Method and apparatus for powering an electrodeless lamp with reduced radio frequency interference  

DOE Patents [OSTI]

An electrodeless lamp waveguide structure includes tuned absorbers for spurious RF signals. A lamp waveguide with an integral frequency selective attenuation includes resonant absorbers positioned within the waveguide to absorb spurious out-of-band RF energy. The absorbers have a negligible effect on energy at the selected frequency used to excite plasma in the lamp. In a first embodiment, one or more thin slabs of lossy magnetic material are affixed to the sidewalls of the waveguide at approximately one quarter wavelength of the spurious signal from an end wall of the waveguide. The positioning of the lossy material optimizes absorption of power from the spurious signal. In a second embodiment, one or more thin slabs of lossy magnetic material are used in conjunction with band rejection waveguide filter elements. In a third embodiment, one or more microstrip filter elements are tuned to the frequency of the spurious signal and positioned within the waveguide to couple and absorb the spurious signal's energy. All three embodiments absorb negligible energy at the selected frequency and so do not significantly diminish the energy efficiency of the lamp. 18 figs.

Simpson, J.E.

1999-06-08T23:59:59.000Z

268

Radio-frequency integrated-circuit design for CMOS single-chip UWB systems  

E-Print Network [OSTI]

switch utilizes the synthetic transmission line concept and multiple reflections technique in order to realize a flat insertion loss less than 1.5 dB from 3.1 GHz to 10.6 GHz and an extremely high isolation of more than 45 dB within this frequency range...

Jin, Yalin

2009-05-15T23:59:59.000Z

269

Occupational and residential 60-Hz electromagnetic fields and high-frequency electric transients: exposure assessment using a new dosimeter  

SciTech Connect (OSTI)

One problem that has limited past epidemiologic studies of cancer and exposure to extremely low-frequency (0-100 Hz) electric and magnetic fields has been the lack of adequate methods for assessing personal exposure to these fields. A new 60-Hz electromagnetic field dosimeter was tested to assess occupational and residential exposures of a group of electrical utility workers and a comparison background group over a 7-day period. Comparing work periods only, utility workers' exposures were significantly higher than background levels by a factor of about 10 for electric (E) and magnetic (B) fields and by a factor of 171 for high-frequency transient electric (HFTE) fields. When overall weekly time-weighted averages combining work and nonwork exposures were compared, ratios of the exposed to background groups were lower. B and HFTE exposure ratios remained statistically significant, with values of 3.5 and 58, respectively, whereas the electric field exposure ratio was no longer significant, with a value of 1.7. E-field exposures of the background group were the highest during the nonwork period, probably reflecting the use of electrical appliances at home. Residential E- and B-field exposures were in the same range as published results from other surveys, whereas occupational E-field exposures tended to be lower than exposures reported in other studies. The high variability associated with occupational exposures probably accounts for the latter discrepancy. Worker acceptance of wearing the dosimeter was good: 95% of participants found it to be of little or no inconvenience while at work. At home, 37% found the device to be inconvenient in its present form but would not object to wearing a slightly smaller and lighter dosimeter.

Deadman, J.E.; Camus, M.; Armstrong, B.G.; Heroux, P.; Cyr, D.; Plante, M.; Theriault, G.

1988-08-01T23:59:59.000Z

270

Identification of Minority Ion-Cyclotron Emission during Radio Frequency Heating in the JET Tokamak  

Science Journals Connector (OSTI)

First measurements and identification of minority ion-cyclotron emission (MICE) during ICRF (H)D minority heating in the JET tokamak are presented. An inner wall radiofrequency (rf) probe shows the new single MICE spectral line, down-shifted from the heating frequency and appearing ?400 ms after the ICRH switch-on. The line is narrow (??/??0.04), characterized by the ion-cyclotron frequency of minority protons in the outer-edge midplane plasma and is observed irrespective of whether single or multifrequency ICRH is applied. The observations are consistent with the classical evolution and population of the plasma edge with ?3 MeV ICRH protons on orbits near the outboard limiters. Particle loss and energy filtering contribute to a local non-Maxwellian energetic ion distribution, which is susceptible to ion-cyclotron instability.

G. A. Cottrell

2000-03-13T23:59:59.000Z

271

Direct measurement of density oscillation induced by a radio-frequency wave  

SciTech Connect (OSTI)

An O-mode reflectometer at a frequency of 25.85 GHz was applied to plasmas heated by the high harmonic fast wave (21 MHz) in the TST-2 spherical tokamak. An oscillation in the phase of the reflected microwave in the rf range was observed directly for the first time. In TST-2, the rf (250 kW) induced density oscillation depends mainly on the poloidal rf electric field, which is estimated to be about 0.2 kV/m rms by the reflectometer measurement. Sideband peaks separated in frequency by ion cyclotron harmonics from 21 MHz, and peaks at ion cyclotron harmonics which are suggested to be quasimodes generated by parametric decay, were detected.

Yamada, T.; Ejiri, A.; Shimada, Y.; Oosako, T.; Tsujimura, J.; Takase, Y.; Kasahara, H. [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Graduate School of Frontier Sciences, University of Tokyo, Kashiwa 277-8561 (Japan); National Institute for Fusion Science, Toki 509-5292 (Japan)

2007-08-15T23:59:59.000Z

272

A Study of Microfluidic Reconfiguration Mechanisms Enabled by Functionalized Dispersions of Colloidal Material for Radio Frequency Applications  

E-Print Network [OSTI]

system component has become known as electromagnetically functionalized colloidal dispersions (EFCDs). In a microfluidic reconfiguration system, they provide electromagnetic agility by altering the colloidal volume fraction of EFCDs - their name...

Goldberger, Sean A.

2010-07-14T23:59:59.000Z

273

Two-dimensional laser-induced fluorescence imaging of metastable density in low-pressure radio frequency argon plasmas with added O2, Cl2,  

E-Print Network [OSTI]

frequency argon plasmas with added O2, Cl2, and CF4 Brian K. McMillina) and M. R. Zachariah Chemical Science, and CF4 on the argon metastable relative density and spatial distribution in low-pressure, radio at the powered electrode. In contrast, the addition of either Cl2 or CF4 was found to significantly modify

Zachariah, Michael R.

274

PHYSICAL REVIEW B VOLUME 48, NUMBER 13 1 OCTOBER 1993-1 Determination of the absolute sign of nuclear quadrupole interactions by laser radio-frequency  

E-Print Network [OSTI]

PHYSICAL REVIEW B VOLUME 48, NUMBER 13 1 OCTOBER 1993-1 Determination of the absolute sign of nuclear quadrupole interactions by laser radio-frequency double-resonance experiments Tilo Blasberg the quadrupole moment of nuclear spins I > + with the electric-field-gradient (EFG) tensor leads to a splitting

Suter, Dieter

275

Compression effects in inductively coupled, high-power radio-frequency discharges for negative hydrogen ion production  

Science Journals Connector (OSTI)

In the paper we present a simplified model description of inductively coupled plasmadischarges operating at a rather high radio-frequency (rf) power. In this case the induced high plasma currents can cause periodic compressions over a substantial radial distance. Such conditions are obviously given in rf driven 1 MHz/150 kW plasma sources developed at the Institute for Plasma Physics Garching for negative (hydrogen) ion production in future neutral beam injection (NBI) systems for nuclear fusion research such as the 1 MeV/50 MW NBI system for the International Thermonuclear Experimental Reactor [T. Inoue R. Hemsworth V. Kulygin and Y. Okumura Fusion Eng. Design 55 291 (2001)]. The given model describes quite well the compression and other features of the discharge. The results include the Ohmic power input (i.e. electron heating) the resulting density build-up and—as a new feature—periodical plasma compressions leading to a direct energy input also into the plasma ions. The model also explains the strange effect of small argon admixtures which improve the negative ion yield in rf sources by a factor of up to 2–3 (but which have no effect in conventional dc arc sources). With the calculated dependencies from external parameters (e.g. rf-power and frequency gas pressure ion mass or the specific geometry) the modeling may help for the further optimization of the rf source.

Rolf Wilhelm

2003-01-01T23:59:59.000Z

276

Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components  

SciTech Connect (OSTI)

There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges.

Subramanyam, Guru, E-mail: gsubramanyam1@udayton.edu [Department of Electrical and Computer Engineering, University of Dayton, Dayton, Ohio 45469 (United States); Cole, M. W., E-mail: melanie.w.cole.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Sun, Nian X. [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Kalkur, Thottam S. [Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, Colorado 80918 (United States); Sbrockey, Nick M.; Tompa, Gary S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Guo, Xiaomei [Boston Applied Technologies, Inc., Woburn, Massachusetts 01801 (United States); Chen, Chonglin [Department of Physics and Astronomy, University of Texas, San Antonio, Texas 78249 (United States); Alpay, S. P.; Rossetti, G. A. [Institute of Materials Science and Materials Science and Engineering Program, University of Connecticut, Storrs, Connecticut 06269 (United States); Dayal, Kaushik [Mechanics, Materials and Computing, Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Chen, Long-Qing [Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802 (United States); Schlom, Darrell G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2013-11-21T23:59:59.000Z

277

Dust removal in radio-frequency plasmas by a traveling potential modulation  

SciTech Connect (OSTI)

The dust contamination in plasma deposition processes plays a crucial role in the quality and the yield of the products. To improve the quality and the yield of plasma processing, a favorable way is to remove the dust particles actively from the plasma reactors.Our recent experiments in the striped electrode device show that a traveling plasma modulation allows for a systematic particle removal independent of the reactor size. Besides the rf powered electrode, the striped electrode device includes a segmented electrode that consists of 100 electrically insulated narrow stripes. A traveling potential profile is produced by the modulation of the voltage signals applied on the stripes. The dust particles are trapped in the potential wells and transported with the traveling of the potential profile.The particle-in-cell (PIC) simulation on the potential above the segmented electrode indicates that the traveling potential profile can be realized either by applying low-frequency (0.1-10 Hz) voltage signals with a fixed phase shift between adjacent stripes or high-frequency (10 kHz a circumflex AS 100 MHz) signals with the amplitudes modulated by a low-frequency envelope. The transportation of the dust particles is simulated with a two-dimensional molecular dynamics (MD) code with the potential profile obtained from the PIC simulation. The MD results reproduce the experimental observations successfully.This technology allows for an active removal of the contaminating particles in processing plasmas and it is independent of the reactor size. The removal velocity is controllable by adjusting the parameters for the modulation.

Li Yangfang; Jiang Ke; Thomas, Hubertus M.; Morfill, Gregor E. [Max-Planck-Institute for Extraterrestrial Physics, 85748 Garching (Germany)

2010-06-16T23:59:59.000Z

278

Experimental observation of delay-induced radio frequency chaos in a transmission line oscillator  

Science Journals Connector (OSTI)

We report an experimental study of fast chaotic dynamics in a delay dynamical system. The system is an electronic device consisting of a length of coaxial cable terminated on one end with a diode and on the other with a negative resistor. When the negative resistance is large the system evolves to a steady state. As the negative resistance is decreased a Hopf bifurcation occurs. By varying the length of the transmission line we observe Hopf frequencies from 7–53? MHz . With the transmission line length fixed we observe a period doubling route to chaos as the negative resistance is further reduced providing the first experimental confirmation of an existing theoretical model for nonlinear dynamics in transmission line oscillators [Corti et al. IEEE Trans. Circ. Syst. I: Fundam. Theory Appl. 41 730 (1994)]. However other experimental results indicate limitations to this model including an inability to predict the Hopf frequency or to produce realistic continuous wave forms. We extend the model to include finite bandwidth effects present in a real negative resistor. The resulting model is a neutral delay differential equation that provides better agreement with experimental results.

Jonathan N. Blakely; Ned J. Corron

2004-01-01T23:59:59.000Z

279

The interaction of radio frequency electromagnetic fields with atmospheric water droplets and application to aircraft ice prevention  

E-Print Network [OSTI]

In this work the physics of advanced microwave anti-icing systems, which pre-heat impinging supercooled water droplets prior to impact, is studied by means of a computer simulation and is found to be feasible. In order to ...

Hansman, Robert John

1982-01-01T23:59:59.000Z

280

Outline of Radio Astronomy  

Science Journals Connector (OSTI)

... about when a technique developed for one type of investigation is applied to another. Radio astronomy is an excellent example of this. During the past seven years the use of ... radio stars' which emit strongly in the radio-frequency portion of the spectrum."Radio Astronomy", by A. C. B. Lovell and J. A. Clegg, gives an ...

J. A. RATCLIFFE

1953-07-11T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Cleaning of inner vacuum surfaces in the Uragan-3M facility by radio-frequency discharges  

SciTech Connect (OSTI)

A method for cleaning vacuum surfaces by a low-temperature (T{sub e} ? 10 eV) relatively dense (n{sub e} ? 10{sup 12} cm{sup ?3}) plasma of an RF discharge was developed and successfully applied at the Uragan-3M torsatron. The convenience of the method is that it can be implemented with the same antenna system and RF generators that are used to produce and heat the plasma in the operating mode and does not require retuning the frequencies of the antennas and RF generators. The RF discharge has a high efficiency from the standpoint of cleaning vacuum surfaces. After performing a series of cleanings by the low-temperature RF discharge plasma (about 20000 pulses), (i) the intensity of the CIII impurity line was substantially reduced, (ii) a quasi-steady operating mode with a duration of up to 50 ms, a plasma density of n{sub e} ? 10{sup 12} cm{sup ?3}, and an electron temperature of up to T{sub e} ? 1 keV was achieved, and (iii) mass spectrometric analysis of the residual gas in the chamber indicated a significant reduction in the impurity content.

Lozin, A. V., E-mail: alexlozin@meta.ua; Moiseenko, V. E.; Grigor’eva, L. I.; Kozulya, M. M.; Kulaga, A. E. [National Science Center Kharkiv Institute of Physics and Technology (Ukraine)] [National Science Center Kharkiv Institute of Physics and Technology (Ukraine); Lysoivan, A. I. [Royal Military Academy, Laboratory for Plasma Physics (Belgium)] [Royal Military Academy, Laboratory for Plasma Physics (Belgium); Mironov, Yu. K.; Pavlichenko, R. O.; Romanov, V. S.; Chernyshenko, V. Ya.; Chechkin, V. V. [National Science Center Kharkiv Institute of Physics and Technology (Ukraine)] [National Science Center Kharkiv Institute of Physics and Technology (Ukraine); Collaboration: Uragan-3M Team

2013-08-15T23:59:59.000Z

282

Experimental test of models of high-plasma-density, radio-frequency sheaths  

Science Journals Connector (OSTI)

Measurements of the rf-bias current and voltage applied to the substrate electrode of a high-density plasma reactor, combined with dc measurements of the ion current at the electrode and capacitive probe measurements of the plasma potential, enabled a rigorous, quantitative test of models of the electrical properties of the sheath adjacent to the electrode. The measurements were performed for argon discharges at 1.33 Pa (10 mTorr), ion current densities of 1.3–13 mA/cm2, rf-bias frequencies of 0.1–10 MHz, and rf-bias voltages from less than 1 to more than 100 V. From the measurements, the current, voltage, impedance, and power of the sheath adjacent to the electrode were determined and were compared to model predictions. The properties of the opposing sheath, adjacent to grounded surfaces, were also determined. The behavior of the two sheaths ranged from nearly symmetric to very asymmetric. Changes in the symmetry are explained by models of the sheath impedance.

Mark A. Sobolewski

1999-01-01T23:59:59.000Z

283

Autocatalytic silver-plating of aluminium radio frequency waveguides with autocatalytic nickel as the undercoat for space applications  

Science Journals Connector (OSTI)

Autocatalytic plating, a technique used for evenly coating contoured items with deep cavities, such as microwave components, irrespective of shape and size of the item to be plated, was used in this work to coat a radio frequency waveguide. In this work, a process sequence was developed for autocatalytic silver plating on aluminum base material with autocatalytic nickel as the undercoat. The thickness of the deposited silver depends on variables like temperature, concentration of silver ions in the electrolyte, and the pH of the solution. The influence of these variables was studied under different process conditions. Silver-coated rectangular plates were subjected to various tests, including a bend test, a heat resistance test, a thermal cycling test, a thermo vacuum test, a solderability test, and a humidity resistance test. Autocatalytic silver-coated RF waveguide WR28 was tested for insertion loss and return loss. Autocatalytic silver-plated rectangular plates and waveguides were found to withstand a simulated space environment.

Sharad Shukla; N Gomathi; Rene George

2014-01-01T23:59:59.000Z

284

THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II  

SciTech Connect (OSTI)

A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19-inch/I-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.

Ma, H.; Rose, J.; Holub, B.; Cupolo, J.; Oliva, J.; Sikora, R.; Yeddulla, M.

2011-03-28T23:59:59.000Z

285

Direct coupling of pulsed radio frequency and pulsed high power in novel pulsed power system for plasma immersion ion implantation  

SciTech Connect (OSTI)

A novel power supply system that directly couples pulsed high voltage (HV) pulses and pulsed 13.56 MHz radio frequency (rf) has been developed for plasma processes. In this system, the sample holder is connected to both the rf generator and HV modulator. The coupling circuit in the hybrid system is composed of individual matching units, low pass filters, and voltage clamping units. This ensures the safe operation of the rf system even when the HV is on. The PSPICE software is utilized to optimize the design of circuits. The system can be operated in two modes. The pulsed rf discharge may serve as either the seed plasma source for glow discharge or high-density plasma source for plasma immersion ion implantation (PIII). The pulsed high-voltage glow discharge is induced when a rf pulse with a short duration or a larger time interval between the rf and HV pulses is used. Conventional PIII can also be achieved. Experiments conducted on the new system confirm steady and safe operation.

Gong Chunzhi; Tian Xiubo; Yang Shiqin [State Key Laboratory of Advanced Welding Production and Technology, School of Materials Science and Engineering, Harbin Institute of Technology, 150001 Harbin (China); Fu, Ricky K. Y.; Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2008-04-15T23:59:59.000Z

286

Convective heat and mass transfer and evolution of the moisture distribution in combined convection and radio frequency drying  

SciTech Connect (OSTI)

In a previous study (Dostie and Navarri, 1994), experiments indicated that a non-uniform moisture distribution could develop in radio frequency drying depending on the applied power and initial conditions, making the design and scale-up of such a dryer a more difficult task. Consequently, a thorough study of the combined convection and RF drying process was undertaken. Experimental results have shown that the values of the heat and mass transfer coefficients decrease with an increase in evaporation rate caused by RF energy. This effect is adequately taken into account by the boundary layer theory. Furthermore, the usual analogy between heat and mass transfer has been verified to apply in RF drying. Experiments have also shown that a different mass transfer resistance on both sides of the product should not result in non-uniform drying. However, it appears that non-uniform drying is dependent upon the initial moisture distribution and the relative intensity of heat transfer by convection and RF. It was shown that the maximum drying rate occurs at a higher average water content and that the total drying time increases with non-uniformity of the initial moisture distribution.

Poulin, A.; Dostie, M.; Kendall, J. [LTEE d`Hydro-Quebec, Shawinigan, Quebec (Canada); Proulx, P. [Univ. de Sherbrooke, Quebec (Canada)

1997-10-01T23:59:59.000Z

287

Radio Data  

Science Journals Connector (OSTI)

... abacs provided now cover wave-lengths down to five metres, while provision is made for audio-frequencies over the range 20-10,000 cycles a second. This publication contains a ... the means for obtaining the inductance, capacitance and reactance of coils and condensers at both audio- and radio-frequencies, charts are given for obtaining the efficiency and time constant of ...

1935-12-21T23:59:59.000Z

288

Proposal for the award of a contract for the supply of electronics for the temperature control of cavity windows and helium gas return lines for the superconducting cavities of the LEP200 radio frequency system  

E-Print Network [OSTI]

Proposal for the award of a contract for the supply of electronics for the temperature control of cavity windows and helium gas return lines for the superconducting cavities of the LEP200 radio frequency system

1991-01-01T23:59:59.000Z

289

Probing the extended emission-line region in 3C 171 with high-frequency radio polarimetry  

Science Journals Connector (OSTI)

......assuming it is cospatial with the EELR, would be 1010 Mo. 1 See http://info.aoc.nrao.edu/vla/html/highfreq/hffastswitch.html 2 See http://info.aoc.nrao.edu/vla/html/refpt.shtml Acknowledgments: The National Radio......

M.J. Hardcastle

2003-02-21T23:59:59.000Z

290

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report  

SciTech Connect (OSTI)

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended for use as an input to the Air Force Environmental Impact Statement as part of the Environmental Impact Analysis Process.

Robertshaw, G.A.; Snyder, A.L.; Weiner, M.M.

1993-05-14T23:59:59.000Z

291

Production of Seamless Superconducting Radio Frequency Cavities from Ultra-fine Grained Niobium, Phase II Final Report  

SciTech Connect (OSTI)

The positron and electron linacs of the International Linear Collider (ILC) will require over 14,000, nine-cell, one meter length, superconducting radio frequency (SRF) cavities [ILC Reference Design Report, 2007]. Manufacturing on this scale will benefit from more efficient fabrication methods. The current methods of fabricating SRF cavities involve deep drawing of the halves of each of the elliptical cells and joining them by high-vacuum, electron beam welding, with at least 19 circumferential welds per cavity. The welding is costly and has undesirable effects on the cavity surfaces, including grain-scale surface roughening at the weld seams. Hydroforming of seamless tubes avoids welding, but hydroforming of coarse-grained seamless tubes results in strain-induced surface roughening. Surface roughness limits accelerating fields, because asperities prematurely exceed the critical magnetic field and become normal conducting. This project explored the technical and economic feasibility of an improved processing method for seamless tubes for hydroforming. Severe deformation of bulk material was first used to produce a fine structure, followed by extrusion and flow-forming methods of tube making. Extrusion of the randomly oriented, fine-grained bulk material proceeded under largely steady-state conditions, and resulted in a uniform structure, which was found to be finer and more crystallographically random than standard (high purity) RRR niobium sheet metal. A 165 mm diameter billet of RRR grade niobium was processed into five, 150 mm I.D. tubes, each over 1.8 m in length, to meet the dimensions used by the DESY ILC hydroforming machine. Mechanical properties met specifications. Costs of prototype tube production were approximately twice the price of RRR niobium sheet, and are expected to be comparable with economies of scale. Hydroforming and superconducting testing will be pursued in subsequent collaborations with DESY and Fermilab. SRF Cavities are used to construct particle accelerators for high-energy physics research, as well as for lower energy particle accelerators, and Free Electron Lasers. These machines have applications in the fields of basic science, industrial processing, medical diagnostics, pharmaceutical research and weapons systems. The scientific community and the general public will benefit from the implementation of this technology since lower production costs will increase the availability of SRF particle accelerators.

Roy Crooks, Ph.D., P.E.

2009-10-31T23:59:59.000Z

292

Cognitive Radio Technology [from THE GUEST EDITORS  

E-Print Network [OSTI]

Cognitive Radio Technology [from THE GUEST EDITORS] Maria Gabriella di Benedetto, Yingbo Hua of cognitive radio. Perhaps the most pressing of them is improved utilization of the electromagnetic radio addressing a multitude of cognitive radio topics were recently approved with a total budget of more than 50

Di Benedetto, Maria-Gabriella

293

High frequency rectenna  

DOE Patents [OSTI]

The invention provides an inexpensive array of rectifying antennas which employ field emission diodes for rectifying electromagnetic waves of microwave frequencies and higher frequencies.

Logan, B. Grant (Danville, CA); Orvis, William J. (Livermore, CA)

1991-01-01T23:59:59.000Z

294

On The Behaviour of Linear Dipole Antennas with Application to Passive Radio Frequency Identification Tags Operating at 869 MHz  

E-Print Network [OSTI]

distributions and read ranges. Also presented are modified dipole structures for optimising the electromagnetic energy launched by the reader. Data for the study are calculated using CST microwave studio which applies. Introduction. The current electronic product code (EPC) initiatives support a global deployment of RFID

Haddadi, Hamed

295

Large scale simulations of solar type III radio bursts: flux density, drift rate, duration and bandwidth  

E-Print Network [OSTI]

Non-thermal electrons accelerated in the solar corona can produce intense coherent radio emission, known as solar type III radio bursts. This intense radio emission is often observed from hundreds of MHz in the corona down to the tens of kHz range in interplanetary space. It involves a chain of physical processes from the generation of Langmuir waves to nonlinear processes of wave-wave interaction. We develop a self-consistent model to calculate radio emission from a non-thermal electron population over large frequency range, including the effects of electron transport, Langmuir wave-electron interaction, the evolution of Langmuir waves due to non-linear wave-wave interactions, Langmuir wave conversion into electromagnetic emission, and finally escape of the electromagnetic waves. For the first time we simulate escaping radio emission over a broad frequency range from 500~MHz down to a few MHz and infer key properties of the radio emission observed: the onset (starting) frequency, {identification as fundament...

Ratcliffe, H; Reid, H A S

2014-01-01T23:59:59.000Z

296

ELECTRON-BEAM-INDUCED RADIO EMISSION FROM ULTRACOOL DWARFS  

SciTech Connect (OSTI)

We present the numerical simulations for an electron-beam-driven and loss-cone-driven electron-cyclotron maser (ECM) with different plasma parameters and different magnetic field strengths for a relatively small region and short timescale in an attempt to interpret the recent discovered intense radio emission from ultracool dwarfs. We find that a large amount of electromagnetic (EM) field energy can be effectively released from the beam-driven ECM, which rapidly heats the surrounding plasma. A rapidly developed high-energy tail of electrons in velocity space (resulting from the heating process of the ECM) may produce the radio continuum depending on the initial strength of the external magnetic field and the electron beam current. Both significant linear polarization and circular polarization of EM waves can be obtained from the simulations. The spectral energy distributions of the simulated radio waves show that harmonics may appear from 10 to 70{nu}{sub pe} ({nu}{sub pe} is the electron plasma frequency) in the non-relativistic case and from 10 to 600{nu}{sub pe} in the relativistic case, which makes it difficult to find the fundamental cyclotron frequency in the observed radio frequencies. A wide frequency band should therefore be covered by future radio observations.

Yu, S.; Doyle, J. G.; Kuznetsov, A. [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Hallinan, G. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Antonova, A. [Department of Astronomy, St. Kliment Ohridski University of Sofia, 5 James Bourchier Blvd., 1164 Sofia (Bulgaria); MacKinnon, A. L. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Golden, A., E-mail: syu@arm.ac.uk [Price Center, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461 (United States)

2012-06-10T23:59:59.000Z

297

Name of the Presentation Fundamental Properties of Electromagnetic RadiationFundamental Properties of Electromagnetic Radiation  

E-Print Network [OSTI]

a continuous spectrum of energy from gamma rays to radio waves. The visible portion of the spectrum may to radio waves. The visible portion of the spectrum may be measured using wavelength (measured between the Sun and the Earth. Electromagnetic Spectrum Electromagnetic Spectrum The Sun produces

298

Project no. 516369 Electromagnetic compatibility between rolling stock and  

E-Print Network [OSTI]

to anything in that environment. Electromagnetic interference (EMI): Degradation of the performance compatibility EMI Electromagnetic interference ETSI European Telecommunications Standards Institute FM Frequency

Paris-Sud XI, Université de

299

The effect of oxygen flow rate and radio frequency plasma power on cubic ZnMgO ultraviolet sensors grown by plasma-enhanced molecular beam epitaxy  

SciTech Connect (OSTI)

Cubic Zn{sub 1-x}Mg{sub x}O thin films were produced by Plasma-Enhanced Molecular Beam Epitaxy. Oxygen flow rate and applied Radio-Frequency (RF) plasma power were varied to investigate the impact on film growth and optoelectronic device performance. Solar-blind and visible-blind detectors were fabricated with metal-semiconductor-metal interdigitated Ni/Mg/Au contacts and responsivity is compared under different growth conditions. Increasing oxygen flow rate and RF plasma power increased Zn incorporation in the film, which leads to phase segregation at relatively high Zn/Mg ratio. Responsivity as high as 61 A/W was measured in phase-segregated ZnMgO visible-blind detectors.

Casey Boutwell, R.; Wei Ming; Schoenfeld, Winston V. [CREOL, College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816-2700 (United States)

2013-07-15T23:59:59.000Z

300

Criteria of radio-frequency ring-shaped hollow cathode discharge using H{sub 2} and Ar gases for plasma processing  

SciTech Connect (OSTI)

In order to achieve high-density capacitively coupled plasma, a radio-frequency (RF) ring-shaped hollow cathode discharge has been developed as a candidate for processing plasma sources. The plasma density in the hollow cathode discharge reaches a high magnitude of 10{sup 10}-10{sup 11} cm{sup -3}. The RF ring-shaped hollow cathode discharge depends on the pressure and mass of the working gas. Criteria required for producing a RF ring-shaped hollow cathode discharge have been investigated for various gas pressures using H{sub 2} and Ar gases for high-density plasma production. The results reveal that the criteria for the occurrence of the hollow cathode effect are that the trench width should be approximately equal to the sum of the electron-neutral mean free paths and twice the sheath thickness of the RF powered electrode.

Ohtsu, Yasunori; Kawasaki, Yujiro [Department of Electrical and Electronic Engineering, Graduate School of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

2013-01-21T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

A self-consistent global model of solenoidal-type inductively coupled plasma discharges including the effects of radio-frequency bias power  

SciTech Connect (OSTI)

We developed a self-consistent global simulator of solenoidal-type inductively coupled plasma discharges and observed the effect of the radio-frequency (rf) bias power on the plasma density and the electron temperature. We numerically solved a set of spatially averaged fluid equations for charged particles, neutrals, and radicals. Absorbed power by electrons is determined by using an analytic electron heating model including the anomalous skin effect. To analyze the effects of rf bias power on the plasma properties, our model also combines the electron heating and global transport modules with an rf sheath module in a self-consistent manner. The simulation results are compared with numerical results by using the commercial software package cfd-ace + (ESI group) and experimental measurements by using a wave cutoff probe and a single Langmuir probe.

Kwon, D. C.; Chang, W. S.; Song, M. Y.; Yoon, J.-S. [Convergence Plasma Research Center, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Park, M. [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); You, D. H. [Kyoungwon Tech, Inc., Seongnam 462-806 (Korea, Republic of); You, S. J. [Center for Vacuum Technology, Korea Research Institute of Standard and Science, Daejeon 305-340 (Korea, Republic of); Im, Y. H. [Division of Chemical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2011-04-01T23:59:59.000Z

302

Shallow acceptor and hydrogen impurity in p-type arsenic-doped ZnMgO films grown by radio frequency magnetron sputtering  

Science Journals Connector (OSTI)

Arsenic-doped ZnMgO films were fabricated on SiO2 by the radio frequency magnetron sputtering technique at different substrate temperatures during growth. The yielded films were characterized by room temperature Hall measurement, x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, nuclear reaction analysis and low-temperature photoluminescence. As-doped samples grown at low substrate temperature (350 °C) were n-type conducting (n ~ 1018 cm?3), with evidence showing that the hydrogen impurity was an important shallow donor associated with the observed n-type conduction. Conversion of n-type to p-type conduction being observed at the substrate temperature of ~400 °C was associated with the formation of the AsZn(VZn)2 shallow acceptor complex and the drastic reduction of the hydrogen content.

J C Fan; G W Ding; S Fung; Z Xie; Y C Zhong; K S Wong; G Brauer; W Anwand; D Grambole; C C Ling

2010-01-01T23:59:59.000Z

303

Wave-wave interactions in solar type III radio bursts  

SciTech Connect (OSTI)

The high time resolution observations from the STEREO/WAVES experiment show that in type III radio bursts, the Langmuir waves often occur as localized magnetic field aligned coherent wave packets with durations of a few ms and with peak intensities well exceeding the strong turbulence thresholds. Some of these wave packets show spectral signatures of beam-resonant Langmuir waves, down- and up-shifted sidebands, and ion sound waves, with frequencies, wave numbers, and tricoherences satisfying the resonance conditions of the oscillating two stream instability (four wave interaction). The spectra of a few of these wave packets also contain peaks at f{sub pe}, 2f{sub pe} and 3 f{sub pe} (f{sub pe} is the electron plasma frequency), with frequencies, wave numbers and bicoherences (computed using the wavelet based bispectral analysis techniques) satisfying the resonance conditions of three wave interactions: (1) excitation of second harmonic electromagnetic waves as a result of coalescence of two oppositely propagating Langmuir waves, and (2) excitation of third harmonic electromagnetic waves as a result of coalescence of Langmuir waves with second harmonic electromagnetic waves. The implication of these findings is that the strong turbulence processes play major roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation in type III radio bursts.

Thejappa, G. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); MacDowall, R. J. [NASA/Goddard Space Flight Center, Greenbelt MD 20771 (United States)

2014-02-11T23:59:59.000Z

304

Poynting-vector based method for determining the bearing and location of electromagnetic sources  

DOE Patents [OSTI]

A method and apparatus is utilized to determine the bearing and/or location of sources, such as, alternating current (A.C.) generators and loads, power lines, transformers and/or radio-frequency (RF) transmitters, emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. When both a source and field sensors (electric and magnetic) are static, a bearing to the electromagnetic source can be obtained. If a single set of electric (E) and magnetic (B) sensors are in motion, multiple measurements permit location of the source. The method can be extended to networks of sensors allowing determination of the location of both stationary and moving sources.

Simons, David J. (Modesto, CA); Carrigan, Charles R. (Tracy, CA); Harben, Philip E. (Livermore, CA); Kirkendall, Barry A. (Golden, CO); Schultz, Craig A. (Danville, CA)

2008-10-21T23:59:59.000Z

305

Comparative study of atmospheric pressure low and radio frequency microjet plasmas produced in a single electrode configuration  

SciTech Connect (OSTI)

Microsize jet-type plasmas were generated in a single pin electrode structure source for two separate input frequencies of 50 kHz and 13.56 MHz in the ambient air. The copper pin electrode radius was 360 {mu}m, and it was placed in a Pyrex tube with a radius of 3 mm for helium gas supply. Due to the input frequency difference, the generated plasmas showed distinct discharge characteristics for their plasma physical appearances, electrical properties, gas temperatures, and optical properties. Strengths and weaknesses of both plasmas were discussed for further applications.

Kim, Dan Bee; Rhee, J. K.; Gweon, B.; Moon, S. Y.; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2007-10-08T23:59:59.000Z

306

Comparative study of atmospheric pressure low and radio frequency microjet plasmas produced in a single electrode configuration  

Science Journals Connector (OSTI)

Microsize jet-type plasmas were generated in a single pin electrode structure source for two separate input frequencies of 50 kHz and 13.56 MHz in the ambient air. The copper pin electrode radius was 360 ? m and it was placed in a Pyrex tube with a radius of 3 mm for helium gas supply. Due to the input frequency difference the generated plasmas showed distinct dischargecharacteristics for their plasma physical appearances electrical properties gas temperatures and optical properties. Strengths and weaknesses of both plasmas were discussed for further applications.

Dan Bee Kim; J. K. Rhee; B. Gweon; S. Y. Moon; W. Choe

2007-01-01T23:59:59.000Z

307

Modulation of redox status and calcium handling by extremely low frequency electromagnetic fields in C2C12 muscle cells: A real-time, single-cell approach  

Science Journals Connector (OSTI)

The biological effects of electric and magnetic fields, which are ubiquitous in modern society, remain poorly understood. Here, we applied a single-cell approach to study the effects of short-term exposure to extremely low frequency electromagnetic fields (ELF-EMFs) on muscle cell differentiation and function using C2C12 cells as an in vitro model of the skeletal muscle phenotype. Our focus was on markers of oxidative stress and calcium (Ca2+) handling, two interrelated cellular processes previously shown to be affected by such radiation in other cell models. Collectively, our data reveal that ELF-EMFs (1) induced reactive oxygen species production in myoblasts and myotubes with a concomitant decrease in mitochondrial membrane potential; (2) activated the cellular detoxification system, increasing catalase and glutathione peroxidase activities; and (3) altered intracellular Ca2+homeostasis, increasing the spontaneous activity of myotubes and enhancing cellular reactivity to a depolarizing agent (KCl) or an agonist (caffeine) of intracellular store Ca2+channels. In conclusion, our data support a possible link between exposure to ELF-EMFs and modification of the cellular redox state, which could, in turn, increase the level of intracellular Ca2+and thus modulate the metabolic activity of C2C12 cells.

Caterina Morabito; Francesca Rovetta; Mariano Bizzarri; Giovanna Mazzoleni; Giorgio Fanò; Maria A. Mariggiò

2010-01-01T23:59:59.000Z

308

Self-consistent particle modeling of radio frequency discharge in Ar/O{sub 2} mixtures: Effects of crossed electric and magnetic fields and partial pressure  

SciTech Connect (OSTI)

A particle-in-cell/Monte Carlo model is developed to study and analyze the electrical characteristics of the nonequilibrium plasma created by radio frequency (RF) discharge in Ar/O{sub 2} mixtures in the presence of crossed electric and magnetic fields. The method of collision treatment is based on an optimized estimation of the free time flight. The needed basic data--more specifically, the ion-neutral cross sections--are determined first. The simulation conditions are 50 mTorr for the total gas pressure and 200 V for the peak of the RF voltage at a frequency of 13.56 MHz. The magnetic field is varied from 0 to 50 G. The effect of the partial pressure ratio of O{sub 2} in the mixture and the effect of the magnitude of the magnetic field are discussed. In particular, the results show an increase of the plasma density that is ten times higher in the presence of a magnetic field.

Benyoucef, Djilali [University of Toulouse, UMR CNRS 5213, Laplace, Toulouse (France); Laboratoire Genie Electrique et Energie Renouvelables, Chlef University (Algeria); Yousfi, Mohammed [University of Toulouse, UMR CNRS 5213, Laplace, Toulouse (France); Belmadani, Bachir [Laboratoire Genie Electrique et Energie Renouvelables, Chlef University (Algeria)

2011-04-15T23:59:59.000Z

309

Electromagnetic Compatibility in Nuclear Power Plants  

SciTech Connect (OSTI)

Electromagnetic compatibility (EMC) has long been a key element of qualification for mission critical instrumentation and control (I&C) systems used by the U.S. military. The potential for disruption of safety-related I&C systems by electromagnetic interference (EMI), radio-frequency interference (RFI), or power surges is also an issue of concern for the nuclear industry. Experimental investigations of the potential vulnerability of advanced safety systems to EMI/RFI, coupled with studies of reported events at nuclear power plants (NPPs) that are attributed to EMI/RFI, confirm the safety significance of EMC for both analog and digital technology. As a result, Oak Ridge National Laboratory has been engaged in the development of the technical basis for guidance that addresses EMC for safety-related I&C systems in NPPs. This research has involved the identification of engineering practices to minimize the potential impact of EMI/RFI and power surges and an evaluation of the ambient electromagnetic environment at NPPs to tailor those practices for use by the nuclear industry. Recommendations for EMC guidance have been derived from these research findings and are summarized in this paper.

Ewing, P.D.; Kercel, S.W.; Korsah, K.; Wood, R.T.

1999-08-29T23:59:59.000Z

310

Assessment of the neurotoxic potential of exposure to 50 Hz extremely low frequency electromagnetic fields (ELF-EMF) in naïve and chemically stressed PC12 cells  

Science Journals Connector (OSTI)

Abstract Increasing exposure to extremely low frequency electromagnetic fields (ELF-EMF), generated by power lines and electric appliances, raises concern about potential adverse health effects of ELF-EMF. The central nervous system is expected to be particularly vulnerable to ELF-EMF as its function strongly depends on electrical excitability. We therefore investigated effects of acute (30 min) and sub-chronic (48 h) exposure to 50 Hz ELF-EMF on naïve and chemically stressed pheochromocytoma (PC12) cells. The latter have higher levels of iron and/or reactive oxygen species (ROS) and display increased vulnerability to environmental insults. Effects of ELF-EMF on Ca2+-homeostasis, ROS production and membrane integrity were assessed using Fura-2 single cell fluorescence microscopy, H2-DCFDA and CFDA assays, respectively. Our data demonstrate that acute exposure of naïve PC12 cells to 50 Hz ELF-EMF up to 1000 ?T fails to affect basal or depolarization-evoked [Ca2+]i. Moreover, sub-chronic ELF-EMF exposure up to 1000 ?T has no consistent effects on Ca2+-homeostasis in naïve PC12 cells and does not affect ROS production and membrane integrity. Notably, in chemically stressed PC12 cells both acute and sub-chronic ELF-EMF exposure also failed to exert consistent effects on Ca2+-homeostasis, ROS production and membrane integrity. Our combined findings thus indicate that exposure to 50 Hz ELF-EMF up to 1000 ?T, i.e. 10,000 times above background exposure, does not induce neurotoxic effects in vitro, neither in naïve nor in chemically stressed PC12 cells. Though our data require confirmation, e.g. in developing neuronal cells in vitro or (developing) animals, it appears that the neurotoxic risk of ELF-EMF exposure is limited.

Martje W.G.D.M. de Groot; Marjolijn D.M. Kock; Remco H.S. Westerink

2014-01-01T23:59:59.000Z

311

First results from the FPGA/NIOS Adaptive FIR Filter Using Linear Prediction Implemented in the AERA Radio Stations to Reduce Narrow Band RFI for Radio Detection of Cosmic Rays  

E-Print Network [OSTI]

The FPGA/NIOS FIR filter based on linear prediction (LP) to suppress radio frequency interference (RFI) has been installed in several radio stations in the Auger Engineering Radio Array (AERA) experiment. AERA observes coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays to make a detailed study of the development of the electromagnetic part of air showers. Radio signals provide complementary information to that obtained from Auger surface detectors, which are predominantly sensitive to the particle content of an air shower at the surface. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10 - 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal...

Szadkowski, Zbigniew; Timmermans, C

2014-01-01T23:59:59.000Z

312

Characteristics of high-purity Cu thin films deposited on polyimide by radio-frequency Ar/H2 atmospheric-pressure plasma jet  

Science Journals Connector (OSTI)

With a view to fabricating future flexible electronic devices an atmospheric-pressure plasma jet driven by 13.56?MHz radio-frequency power is developed for depositing Cu thin films on polyimide where a Cu wire inserted inside the quartz tube was used as the evaporation source. A polyimide substrate is placed on a water-cooled copper heat sink to prevent it from being thermally damaged. With the aim of preventing oxidation of the deposited Cu film we investigated the effect of adding H2 to Ar plasma on film characteristics. Theoretical fitting of the OH emission line in OES spectrum revealed that adding H2 gas significantly increased the rotational temperature roughly from 800 to 1500?K. The LMM Auger spectroscopy analysis revealed that higher-purity Cu films were synthesized on polyimide by adding hydrogen gas. A possible explanation for the enhancement in the Cu film deposition rate and improvement of purity of Cu films by H2 gas addition is that atomic hydrogen produced by the plasma plays important roles in heating the gas to promote the evaporation of Cu atoms from the Cu wire and removing oxygen from copper oxide components via reduction reaction.

P. Zhao; W. Zheng; Y. D. Meng; M. Nagatsu

2013-01-01T23:59:59.000Z

313

Effects of the shielding cylinder and substrate on the characteristics of an argon radio-frequency atmospheric glow discharge plasma jet  

SciTech Connect (OSTI)

With unique features of low breakdown voltages, large and uniform discharge areas and high concentrations of chemically reactive species, radio-frequency, atmospheric-pressure glow discharge (rf APGD) plasma sources produced with bare-metallic electrodes have shown promising prospects in the field of materials processing. In this paper, the spatial distributions (i.e., the directly measured integrated axial distribution and the radial distribution by using the inverse Abel transform) of the emission intensities of the Ar I 696.5 nm line are studied for the argon rf APGD plasma jet under different operation conditions, including variations of the rf power input or the argon flow rate, the existence of the solid shielding cylinder or the substrate. The experimental results show that, with other parameters being unchanged, the emission intensities of the Ar I 696.5 nm line increase with increasing the rf power input or the argon flow rate; and the solid shielding cylinder has more significant influences on the characteristics of the plasma impinging jet by reducing the mass flow rate of the ambient air entrained into the plasma jet region than those for the cases without the existence of the substrate at the downstream of the plasma torch nozzle exit.

Li Guo; Le Peisi; Li Heping; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2010-05-15T23:59:59.000Z

314

Radio frequency emission from high-pressure xenon arcs: A systematic experimental analysis of the underlying near-anode plasma instability  

SciTech Connect (OSTI)

High-pressure Xe discharge lamps at DC operation can show unwanted strong RF (radio-frequency) emission to beyond 1 GHz, correlated to a sharp periodic lamp-voltage instability in the near-anode plasma with a pulse repetition rate {epsilon} of 1-10 MHz. The physical origin of the instability is unclear. Here, its existence and pulse rate have been measured as a function of arc current I = 0.2-1.2 A and anode temperature T{sub a} = 1700-3400 K independently, in experimental lamps with pure-tungsten electrodes and a Xe operating pressure around p = 10 MPa. Surprisingly, the instability is not affected by I or current density j but exists if T{sub a} is lower than a threshold value around 2800-2900 K. The pulse rate {epsilon} is simply a rising linear function of the inverse anode temperature 1/T{sub a}, with only a small I-dependent correction. The average anode heat load is slightly lower in the unstable regime and possibly depends on {epsilon}. The results allow a consistent re-interpretation of earlier and present experimental observations and should be both a valuable help in practical lamp engineering and a tight constraint for future theories of this effect.

Hechtfischer, Ulrich [Philips Lighting, GBU Automotive Lamps, Technology, Philipsstrasse 8, 52068 Aachen (Germany)

2011-10-01T23:59:59.000Z

315

Observation of radio frequency ring-shaped hollow cathode discharge plasma with MgO and Al electrodes for plasma processing  

SciTech Connect (OSTI)

Various high-density plasma sources have been proposed for plasma processing. Especially, the hollow cathode discharge is one of the powerful ones. In this work, radio-frequency (RF) driven ring-shaped hollow cathode discharges with high secondary-electron emission have been investigated, using an aluminum (Al) cathode, coated or not with magnesium oxide (MgO). The thickness of MgO thin film is approximately 200?nm. The RF discharge voltage for the coated cathode is almost the same as that for the uncoated one, in a wide range of Ar gas pressure, from 5.3 to 53.2?Pa. The results reveal that the plasma density has a peak at an Ar gas pressure of 10.6?Pa for both cathodes. The plasma density for the coated cathode is about 1.5–3 times higher than that for the uncoated one, at various gas pressures. To the contrary, the electron temperature for the coated cathode is lower than temperature obtained with the uncoated cathode, at various gas pressures. Radial profiles of electron saturation current, which is proportional to plasma flux, are also examined for a wide range of gas pressure. Radial profiles of electron temperature at various axial positions are almost uniform for both cathodes so that the diffusion process due to density gradient is dominant for plasma transport. The secondary electrons emitted from the coated cathode contribute to the improvement of the plasma flux radial profile obtained using the uncoated cathode.

Ohtsu, Yasunori, E-mail: ohtsuy@cc.saga-u.ac.jp; Matsumoto, Naoki [Department of Electrical and Electronic Engineering, Graduate School of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

2014-05-15T23:59:59.000Z

316

A new electromagnetic code for ICRF antenna in EAST  

E-Print Network [OSTI]

The demand for an effective tool to help in the design of ion cyclotron radio frequency (ICRF) antenna system for fusion experiment has driven the development of predictive codes. A new electromagnetic code based on the method of moments (MOM) is described in the paper. The code computes the electromagnetic field by the solution of the electric field integral equation. The structure of ICRF antennas are discretized with triangular mesh. By using the new code, the scattering parameter and the surface current are given and compared with the result by commercial code CST. Moreover, the power spectra are studied with different toroidal phases for heating and current drive. Good agreement of simulation results between the new code and CST are obtained. The code has been validated against CST for EAST ICRF antenna.

Yang, Hua; Dong, Sa; Zhang, Xin-Jun; Zhao, Yan-Ping; Shang, Lei

2015-01-01T23:59:59.000Z

317

High frequency (900 MHz) low amplitude (5 V m?1) electromagnetic field: a genuine environmental stimulus that affects transcription, translation, calcium and energy charge in tomato  

Science Journals Connector (OSTI)

Using an especially-designed facility, the Mode Stirred Reverberation Chamber, we exposed tomato plants (Lycopersicon esculentum...Mill. VFN8) to low level (900 MHz, 5 V m?1) electromagnetic fields for a short pe...

David Roux; Alain Vian; Sébastien Girard; Pierre Bonnet; Françoise Paladian…

2008-03-01T23:59:59.000Z

318

Coherent hybrid electromagnetic field imaging  

DOE Patents [OSTI]

An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

Cooke, Bradly J. (Jemez Springs, NM); Guenther, David C. (Los Alamos, NM)

2008-08-26T23:59:59.000Z

319

System Design for Cognitive Radio Communications  

E-Print Network [OSTI]

about an increasing demand for frequency spectrum. Cognitive radio offers a tempting solution, in which frequency bands that are not being used by their licensed users are utilized by cognitive radios. Since cognitive radios do not need to have a license and since they do not affect the operation

Arslan, Hüseyin

320

Nonlocal theory of electromagnetic wave decay into two electromagnetic waves in a rippled density plasma channel  

SciTech Connect (OSTI)

Parametric decay of a large amplitude electromagnetic wave into two electromagnetic modes in a rippled density plasma channel is investigated. The channel is taken to possess step density profile besides a density ripple of axial wave vector. The density ripple accounts for the momentum mismatch between the interacting waves and facilitates nonlinear coupling. For a given pump wave frequency, the requisite ripple wave number varies only a little w.r.t. the frequency of the low frequency decay wave. The radial localization of electromagnetic wave reduces the growth rate of the parametric instability. The growth rate decreases with the frequency of low frequency electromagnetic wave.

Sati, Priti; Tripathi, V. K. [Indian Institute of Technology, Hauz Khas, Delhi 110054 (India)

2012-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Self consistent radio-frequency wave propagation and peripheral direct current plasma biasing: Simplified three dimensional non-linear treatment in the 'wide sheath' asymptotic regime  

SciTech Connect (OSTI)

A minimal two-field fluid approach is followed to describe the radio-frequency (RF) wave propagation in the bounded scrape-off layer plasma of magnetic fusion devices self-consistently with direct current (DC) biasing of this plasma. The RF and DC parts are coupled by non-linear RF and DC sheath boundary conditions at both ends of open magnetic field lines. The physical model is studied within a simplified framework featuring slow wave (SW) only and lateral walls normal to the straight confinement magnetic field. The possibility is however kept to excite the system by any realistic 2D RF field map imposed at the outer boundary of the simulation domain. The self-consistent RF + DC system is solved explicitly in the asymptotic limit when the width of the sheaths gets very large, for several configurations of the RF excitation and of the target plasma. In the case of 3D parallelepipedic geometry, semi-analytical results are proposed in terms of asymptotic waveguide eigenmodes that can easily be implemented numerically. The validity of the asymptotic treatment is discussed and is illustrated by numerical tests against a quantitative criterion expressed from the simulation parameters. Iterative improvement of the solution from the asymptotic result is also outlined. Throughout the resolution, key physical properties of the solution are presented. The radial penetration of the RF sheath voltages along lateral walls at both ends of the open magnetic field lines can be far deeper than the skin depth characteristic of the SW evanescence. This is interpreted in terms of sheath-plasma wave excitation. Therefore, the proper choice of the inner boundary location is discussed as well as the appropriate boundary conditions to apply there. The asymptotic scaling of various quantities with the amplitude of the input RF excitation is established.

Colas, L.; Jacquot, J.; Hillairet, J.; Goniche, M. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Heuraux, S.; Faudot, E. [IJL-P2M UMR 7198 CNRS, F-54506 Vandoeuvre les Nancy (France); Crombe, K. [Department of Applied Physics, Ghent University, B-9000 Ghent (Belgium); Kyrytsya, V. [LPP-ERM/KMS, Association Euratom-'Belgian State', TEC Partner, Brussels (Belgium)

2012-09-15T23:59:59.000Z

322

Implications of fast radio bursts for superconducting cosmic strings  

E-Print Network [OSTI]

Highly beamed, short-duration electromagnetic bursts could be produced by superconducting cosmic string (SCS) loops oscillating in cosmic magnetic fields. We demonstrated that the basic characteristics of SCS bursts such as the electromagnetic frequency and the energy release could be consistently exhibited in the recently discovered fast radio bursts (FRBs). Moreover, it is first showed that the redshift distribution of the FRBs can also be well accounted for by the SCS burst model. Such agreements between the FRBs and SCS bursts suggest that the FRBs could originate from SCS bursts and thus they could provide an effective probe to study SCSs. The obtained values of model parameters indicate that the loops generating the FRBs have a small length scale and they are mostly formed in the radiation-dominated cosmological epoch.

Yu, Yun-Wei; Shiu, Gary; Tye, Henry

2014-01-01T23:59:59.000Z

323

Radio Astronomy: Conflict of Frequencies  

Science Journals Connector (OSTI)

...300 per year, and the cost to the government for...per-sons imiade invalid bs par.asitic diseases...price, consult your local Nuclear-Chicago sales engineer...us. NUC:0-6-247 NUCLEAR-CHICAGO CORPORATION...Photometric Titralyzer costs $3300. Write today for...

G. W. Swenson Jr.; R. N. Bracewell

1967-02-03T23:59:59.000Z

324

Low reflectance radio frequency load  

DOE Patents [OSTI]

A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

Ives, R. Lawrence; Mizuhara, Yosuke M

2014-04-01T23:59:59.000Z

325

Demonstration of Real-time Spectrum Sensing for Cognitive Radio  

E-Print Network [OSTI]

Demonstration of Real-time Spectrum Sensing for Cognitive Radio Zhe Chen, Nan Guo, and Robert C sensing detects the availability of the radio frequency spectrum in a real-time fashion, which is essen Cognitive radio (CR) has been put forward to make effi- cient use of scarce radio frequency spectrum

Qiu, Robert Caiming

326

High-frequency self-aligned graphene transistors with transferred gate stacks  

Science Journals Connector (OSTI)

...2009 ) Radio-frequency electrical...Epitaxial-graphene RF field-effect...2011 ) High-frequency, scaled graphene...of high-frequency measurement...Information (PDF) High-frequency self-aligned...attention for radio-frequency transistor...

Rui Cheng; Jingwei Bai; Lei Liao; Hailong Zhou; Yu Chen; Lixin Liu; Yung-Chen Lin; Shan Jiang; Yu Huang; Xiangfeng Duan

2012-01-01T23:59:59.000Z

327

Abstract--We consider the problem of Spectrum Sensing in Cogni-tive Radio Systems. We have developed a distributed algorithm that  

E-Print Network [OSTI]

Abstract-- We consider the problem of Spectrum Sensing in Cogni- tive Radio Systems. We have sig- nificantly less energy. Keywords: Cognitive Radio, Spectrum Sensing, CUSUM, De- centralized Sequential Detection I. INTRODUCTION HE Electromagnetic Radio Spectrum, a natural resource, is currently

Sharma, Vinod

328

Hybrid spread spectrum radio system  

DOE Patents [OSTI]

Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

Smith, Stephen F. (London, TN) [London, TN; Dress, William B. (Camas, WA) [Camas, WA

2010-02-09T23:59:59.000Z

329

Excitation of electrostatic waves in the electron cyclotron frequency range during magnetic reconnection in laboratory overdense plasmas  

SciTech Connect (OSTI)

We report the observation of electromagnetic radiation at high harmonics of the electron cyclotron frequency that was considered to be converted from electrostatic waves called electron Bernstein waves (EBWs) during magnetic reconnection in laboratory overdense plasmas. The excitation of EBWs was attributed to the thermalization of electrons accelerated by the reconnection electric field around the X-point. The radiative process discussed here is an acceptable explanation for observed radio waves pulsation associated with major flares.

Kuwahata, A., E-mail: kuwahata@ts.t.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Igami, H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Kawamori, E. [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China); Kogi, Y. [Fukuoka Institute of Technology, Fukuoka 811-0295 (Japan); Inomoto, M.; Ono, Y. [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561 (Japan)

2014-10-15T23:59:59.000Z

330

A newsletter for non-scientists (and scientists) interested in MAGIC Radars transmit pulses of radio waves of a given frequency and receive signals that are  

E-Print Network [OSTI]

and the speed of propagation of radio waves, which is the speed of light. To understand why the Doppler effect by the distance to the object and the speed of light. As all oscillations travel the same distance and at the same of the Doppler effect in everyday life is the radar gun, whether used for measuring the speed of baseballs

331

Electromagnetic Signals from Bacterial DNA  

E-Print Network [OSTI]

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

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

2012-02-09T23:59:59.000Z

332

Semiconductor converters of electric energy electromagnetic and electromechanical processes in an electric drive under frequency converter parallel operation to induction motor  

Science Journals Connector (OSTI)

The processes occurring in the two PWM-controlled frequency converters operating in parallel to an induction motor in the high-power electric drive’s start and self-start modes ... current consumed from the suppl...

D. V. Belyaev; A. M. Veinger; G. B. Lazarev…

2007-05-01T23:59:59.000Z

333

The Rapidly Pulsating Radio Source in Vulpecula  

Science Journals Connector (OSTI)

...ob-served frequencies (Table 1...the pulse radio frequency as a function...is the % plasma frequency...near 100 Mhz are given...fre-quency (RF) as a function of frequency. The straight...those at 430 Mhz by 0.279...than the plasma and cyclotron...arrival time at high frequency. High Low...

F. D. Drake; E. J. Gundermann; D. L. Jauncey; J. M. Comella; G. A. Zeissig; H. D. Craft Jr.

1968-05-03T23:59:59.000Z

334

Planck early results: Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources  

E-Print Network [OSTI]

Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalog (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ranging from radio to gamma-rays. This is the first extensive frequency coverage in the radio and millimetre domains for an essentially complete sample of extragalactic radio sources, and it shows how the individual shocks, each in their own phase of development, moving in the relativistic jet, shape the radio spectra. The SEDs presented in this paper were fitted with second and third degree polynomials to estimate the frequencies of the synchrotron and inverse Compton (IC) peaks, and the spectral indices of low and high frequency radio data, including the Planck ERCSC data, were calculated. SED modelling methods are discussed, with an emphasis on proper, physical modelli...

Aatrokoski, J; Aghanim, N; Aller, H D; Aller, M F; Angelakis, E; Arnaud, M; Ashdown, M; Aumont, J; Baccigalupi, C; Balbi, A; Banday, A J; Barreiro, R B; Bartlett, J G; Battaner, E; Benabed, K; Benoît, A; Berdyugin, A; Bernard, J -P; Bersanelli, M; Bhatia, R; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Bucher, M; Burigana, C; Burrows, D N; Cabella, P; Capalbi, M; Cappellini, B; Cardoso, J -F; Catalano, A; Cavazzuti, E; Cayón, L; Challinor, A; Chamballu, A; Chary, R -R; Chiang, L -Y; Christensen, P R; Clements, D L; Colafrancesco, S; Colombi, S; Couchot, F; Coulais, A; Cutini, S; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Gasperis, G; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Dickinson, C; Dole, H; Donzelli, S; Doré, O; Dörl, U; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Fuhrmann, L; Galeotta, S; Ganga, K; Gargano, F; Gasparrini, D; Gehrels, N; Giard, M; Giardino, G; Giglietto, N; Giommi, P; Giordano, F; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Harrison, D; Henrot-Versillé, S; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hovest, W; Hoyland, R J; Huffenberger, K M; Jaffe, A H; Juvela, M; Keihänen, E; Keskitalo, R; King, O; Kisner, T S; Kneissl, R; Knox, L; Krichbaum, T P; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lavonen, N; Lawrence, C R; Leach, S; Leonardi, R; León-Tavares, J; Linden-V\\ornle, M; Lindfors, E; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Maino, D; Mandolesi, N; Mann, R; Maris, M; Martínez-González, E; Masi, S; Massardi, M; Matarrese, S; Matthai, F; Max-Moerbeck, W; Mazziotta, M N; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Michelson, P F; Mingaliev, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Monte, C; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, A; Naselsky, P; Natoli, P; Nestoras, I; Netterfield, C B; Nieppola, E; Nilsson, K; N\\orgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; O'Dwyer, I J; Osborne, S; Pajot, F; Partridge, B; Pasian, F; Patanchon, G; Pavlidou, V; Pearson, T J; Perdereau, O; Perotto, L; Perri, M; Perrotta, F; Piacentini, F; Piat, M; Plaszczynski, S; Platania, P; Pointecouteau, E; Polenta, G; Ponthieu, N; Poutanen, T; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Rainó, S; Reach, W T; Readhead, A; Rebolo, R; Reeves, R; Reinecke, M; Reinthal, R; Renault, C; Ricciardi, S; Richards, J; Riller, T; Riquelme, D; Ristorcelli, I; Rocha, G; Rosset, C; Rowan-Robinson, M; Rubi\; Rusholme, B; Saarinen, J; Sandri, M; Savolainen, P; Scott, D; Seiffert, M D; Sievers, A; Sillanpää, A; Smoot, G F; Sotnikova, Y; Starck, J -L; Stevenson, M; Stivoli, F; Stolyarov, V; Sudiwala, R; Sygnet, J -F; Takalo, L; Tammi, J; Tauber, J A; Terenzi, L; Thompson, D J; Toffolatti, L; Tomasi, M; Tornikoski, M; Torre, J -P; Tosti, G; Tramacere, A; Tristram, M; Tuovinen, J; Türler, M; Turunen, M; Umana, G; Ungerechts, H; Valenziano, L; Valtaoja, E; Varis, J; Verrecchia, F; Vielva, P; Villa, F; Vittorio, N; Wandelt, B D; Wu, J; Yvon, D; Zacchei, A; Zensus, J A; Zhou, X; Zonca, A

2011-01-01T23:59:59.000Z

335

Electromagnetic Theory 1 /56 Electromagnetic Theory  

E-Print Network [OSTI]

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

Bicknell, Geoff

336

Electromagnetic Geometry  

E-Print Network [OSTI]

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

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

2011-11-08T23:59:59.000Z

337

Electromagnetic wave propagation through an overdense magnetized collisional plasma layer  

SciTech Connect (OSTI)

The results of investigations into the feasibility of using a magnetic window to propagate electromagnetic waves through a finite-sized overdense plasma slab are described. We theoretically calculate the transmission coefficients for right- and left-handed circularly polarized plane waves through a uniform magnetized plasma slab. Using reasonable estimates for the plasma properties expected to be found in the ionized shock layer surrounding a hypersonic aircraft traveling in the earth's upper atmosphere (radio blackout conditions), and assuming a 1 GHz carrier frequency for the radio communications channel, we find that the required magnetic field for propagation of right-handed circularly polarized, or whistler, waves is on the order of a few hundred gauss. Transmission coefficients are calculated as a function of sheath thickness and are shown to be quite sensitive to the electron collision frequency. One-dimensional particle-in-cell simulations are shown to be in good agreement with the theory. These simulations also demonstrate that Ohmic heating of the electrons can be considerable. Two- and three-dimensional particle-in-cell simulations using a simplified waveguide and antenna model illustrate the same general transmission behavior as the theory and one-dimensional simulations. In addition, a net focusing effect due to the plasma is also observed in two and three dimensions. These simulations can be extended to design and analyze more realistic waveguide and antenna models.

Thoma, C.; Rose, D. V.; Miller, C. L.; Clark, R. E.; Hughes, T. P. [Voss Scientific LLC, Albuquerque, New Mexico 87108 (United States)

2009-08-15T23:59:59.000Z

338

Experimental methodology for non-thermal effects of electromagnetic radiation on biologics  

E-Print Network [OSTI]

Appropriate equipment is needed for research on the effects of radio-frequency radiation from radio-frequency identification (RF-ID) systems on biological materials. In the present study, a complete test system comprising ...

Cox, Felicia C. A. I

2006-01-01T23:59:59.000Z

339

Electromagnetic Waves Propagation in 3D Plasma Configurations  

E-Print Network [OSTI]

Electromagnetic Waves Propagation in 3D Plasma Configurations Pavel Popovich, W. Anthony Cooper such method is based on heating the plasma by electromagnetic waves with various frequencies. Wave behaviour that allows to simulate mode-conversion effects. The wave equation is formulated in terms of electromagnetic

340

Electromagnetic Reciprocity.  

SciTech Connect (OSTI)

A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a geophysical consultant ) and Dr. Chester J. Weiss (recently rejoined with Sandia National Laboratories) for many stimulating (and reciprocal!) discussions regar ding the topic at hand.

Aldridge, David F.

2014-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

The radio spectrum of Sgr A*  

E-Print Network [OSTI]

We discuss the radio spectrum of Sgr A* \\index{Sgr A*, radio spectrum} in the frequency range between $\\approx 1\\,{\\rm GHz}$ and $\\approx 1\\,000\\,{\\rm GHz}$, show that it can be explained by optically thin synchrotron radiation \\index{Sgr A*, synchrotron radiation, optically thin} of relativistic electrons, and point toward a possible correlation between the spectrum of Sgr A* and larger-scale ($\\la 50\\,{\\rm pc}$) radio emission from the Galactic Center \\index{Galactic Center} region.

Wolfgang J. Duschl; Harald Lesch

1994-11-03T23:59:59.000Z

342

Shielding Effectiveness Density Theory for Carbon Fiber/ Nylon 6,6 Composites  

E-Print Network [OSTI]

applications in electromagnetic interference and radio frequency interference, and is validated here, semiconductive (e.g., fuel gauges, etc.), and electromagnetic interference / radio frequency interference (EMI

Perger, Warren F.

343

Hybrid spread spectrum radio system  

DOE Patents [OSTI]

Systems and methods are described for hybrid spread spectrum radio systems. A method includes modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control an amplification circuit that provides a gain to the signal. Another method includes: modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control a fast hopping frequency synthesizer; and fast frequency hopping the signal with the fast hopping frequency synthesizer, wherein multiple frequency hops occur within a single data-bit time.

Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)

2010-02-02T23:59:59.000Z

344

An Optimization of the FPGA Based Wavelet Trigger in Radio Detection of Cosmic Rays  

E-Print Network [OSTI]

Experiments that observe coherent radio emission from extensive air showers induced by ultra-high energy cosmic rays are designed for a detailed study of the development of the electromagnetic part of air showers. Radio detectors can operate with 100% up time as e.g. surface detectors based on water-Cherenkov tanks. They are being developed for ground-based experiments (e.g. the Pierre Auger Observatory) as another type of air shower detector in addition to the fluorescence detectors, which operate with only ~10% of duty in dark nights. The radio signals from air showers are caused by the coherent emission due to geomagnetic radiation and charge excess processes. Currently used self-triggers in radio detectors often generate a dense stream of data, which is analyzed afterwards. Huge amounts of registered data requires a significant man-power for the off-line analysis. An improvement of the trigger efficiency becomes a relevant factor. In this work, Morlet wavelets with various scaling factors were used for an analysis of real data from the Auger Engineering Radio Array and for an optimization of the utilization of the resources in an FPGA. The wavelet analysis showed that the power of events is concentrated mostly in a limited range of the frequency spectrum (consistent with a range imposed by the input analog band-pass filter). However, we found several events with suspicious spectral characteristics, where the signal power is spread over the full band-width sampled by a 200 MHz digitizer with significant contribution of very high and very low frequencies. These events may not origin from cosmic ray showers but can be human-made contaminations. The engine of the wavelet analysis can be implemented into the modern powerful FPGA and can remove suspicious events on-line to reduce the trigger rate.

Zbigniew Szadkowski for the Pierre Auger Collaboration

2014-06-04T23:59:59.000Z

345

Cryptographic Link Signatures for Spectrum Usage Authentication in Cognitive Radio  

E-Print Network [OSTI]

Cryptographic Link Signatures for Spectrum Usage Authentication in Cognitive Radio Xi Tan, Kapil frequency spectrum was inefficiently utilized. To fully use these spectrums, cognitive radio networks have of cognitive radio is to enable the current fixed spectrum channels assigned by Federal Communica- tions

Du, Wenliang "Kevin"

346

Quickest Spectrum Detection Using Hidden Markov Model for Cognitive Radio  

E-Print Network [OSTI]

Quickest Spectrum Detection Using Hidden Markov Model for Cognitive Radio Zhe Chen, Zhen Hu, Robert and recognition under the umbrella of cognitive radio. In the procedure of spectrum recognition, a frequency) opened free white space spectrum on November 4, 2008 [1]. Cognitive radio has been put forward as a more

Qiu, Robert Caiming

347

Category:Electromagnetic Profiling Techniques | Open Energy Information  

Open Energy Info (EERE)

source source History View New Pages Recent Changes All Special Pages Semantic Search/Querying Get Involved Help Apps Datasets Community Login | Sign Up Search Category Edit History Facebook icon Twitter icon » Category:Electromagnetic Profiling Techniques Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Geothermalpower.jpg Looking for the Electromagnetic Profiling Techniques page? For detailed information on Electromagnetic Profiling Techniques, click here. Category:Electromagnetic Profiling Techniques Add.png Add a new Electromagnetic Profiling Techniques Technique Pages in category "Electromagnetic Profiling Techniques" This category contains only the following page. F Frequency-Domain Electromagnetic Survey Retrieved from "http://en.openei.org/w/index.php?title=Category:Electromagnetic_Profiling_Techniques&oldid=689835"

348

Dangerous electromagnetic fields?  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Dangerous electromagnetic fields? Dangerous electromagnetic fields? Name: Tommy T Joseph Location: N/A Country: N/A Date: N/A Question: Why are electromagnetic fields supposedly dangerous? Replies: I assume you are asking about power line frequency (60 Hz) fields, since they have been in the news lately. No one knows for sure that they are dangerous. There have been a few studies which seem to show an association between how close homes are to power lines, and the incidence of childhood cancer (mostly leukemia) in children living (or who have lived) in those homes. Other similar studies have not found such an association. In all the studies which have found an association, none has actually measured the fields. Studies which actually have measured the fields find no association. There is no known mechanism for 60 Hz fields to cause cancer. Furthermore, the classic "dose-response relationship," that is, the greater the dose, the greater the response, does not seem to work here. Many laboratory studies have found that 60 Hz fields have an effect on organisms under certain conditions, but none of the observed effects can be convincingly related to a hazard. The bottom line is, no one knows for sure. It is important to realize that it is impossible to prove that anything is completely safe. My personal opinion is that, if there is a risk, it must be very small, or it wouldn't be so hard to prove. I can supply some good unbiased references if you are interested.

349

Electromagnetically induced invisibility cloaking  

E-Print Network [OSTI]

Invisibility cloaking imposes strict conditions on the refractive index profiles of cloaking media that must be satisfied to successfully hide an object. The first experimental demonstrations of cloaking used artificial metamaterials to respond to this challenge. In this work we show how a much simpler technique of electromagnetically induced transparency can be used to achieve a partial, {\\it carpet} cloaking at optical frequencies in atomic vapours or solids. To generate a desired combination of low absorption with strong modifications of the refractive index, we use chiral media with an induced magneto-electrical cross-coupling. We demonstrate that high-contrast positive refractive indices can be attained by fine tuning the material with a gradient magnetic field and calculate the parameters required to construct a carpet cloak.

Darran F. Milne; Natalia Korolkova

2012-06-18T23:59:59.000Z

350

Susceptibility of digital instrumentation and control systems to disruption by electromagnetic interference  

SciTech Connect (OSTI)

The potential for disruption of safety-related digital instrumentation and control (I&C) systems by electromagnetic interference/radio-frequency interference (EMI/RFI) bears directly on the safe operation of advanced reactors. It is anticipated that the use of digital I&C equipment for safety and control functions will be substantially greater for advanced reactor designs than for current-generation nuclear reactors, which primarily use analog I&C equipment. In the absence of significant operational experience, the best available indication of the potential vulnerability of advanced digital safety systems to EMI/RFI comes from environmental testing of an experimental digital safety channel (EDSC) by the Oak Ridge National Laboratory (ORNL). The EDSC is a prototypical system representative of advanced reactor safety system designs with regard to architecture, functionality and communication protocols, and board and component fabrication technologies. An understanding of the electromagnetic environment to be expected for advanced reactors can be drawn from ORNL`s survey of ambient EMI/RFI conditions in the current Generation of nuclear power plants. A summary of the results from these research efforts is reported in this paper. The lessons learned from the EMI/RFI survey and the EDSC tests contribute significantly to determining the best approach to assuring electromagnetic compatibility for the safety-related I&C systems of advanced reactors. 16 refs., 2 figs., 3 tabs.

Kercel, S.W.; Korsah, K.; Wood, R.T. [Oak Ridge National Lab., TN (United States)

1997-12-01T23:59:59.000Z

351

Susceptibility of digital instrumentation and control systems to disruption by electromagnetic interference  

SciTech Connect (OSTI)

The potential for disruption of safety-related digital instrumentation and control (I and C) systems by electromagnetic interference/radio-frequency interface (EMI/RFI) bears directly on the safe operation of advanced reactors. It is anticipated that the use of digital I and C equipment for safety and control functions will be substantially greater for advanced reactor designs than for current-generation nuclear reactors, which primarily use analog I and C equipment. In the absence of significant operational experience, the best available indication of the potential vulnerability of advanced digital safety systems to EMI/RFI comes from environmental testing of an experimental digital safety channel (EDSC) by the Oak Ridge National Laboratory (ORNL). The EDSC is a prototypical system representative of advanced reactor safety system designs with regard to architecture, functionality and communication protocols, and board and component fabrication technologies. An understanding of the electromagnetic environment to be expected for advanced reactors can be drawn from ORNL`s survey of ambient EMI/RFI conditions in the current generation of nuclear power plants. A summary of the results from these research efforts is reported in this paper. The lessons learned from the EMI/RFI survey and the EDSC tests contribute significantly to determining the best approach to assuring electromagnetic compatibility for the safety-related I and C systems of advanced reactors.

Kercel, S.W.; Korsah, K.; Wood, R.T.

1997-10-01T23:59:59.000Z

352

MULTIMOMENT RADIO TRANSIENT DETECTION  

SciTech Connect (OSTI)

We present a multimoment technique for signal classification and apply it to the detection of fast radio transients in incoherently dedispersed data. Specifically, we define a spectral modulation index in terms of the fractional variation in intensity across a spectrum. A signal whose intensity is distributed evenly across the entire band has a lower modulation index than a spectrum whose intensity is localized in a single channel. We are interested in broadband pulses and use the modulation index to excise narrowband radio frequency interference by applying a modulation index threshold above which candidate events are removed. The technique is tested both with simulations and using data from known sources of radio pulses (RRAT J1928+15 and giant pulses from the Crab pulsar). The method is generalized to coherent dedispersion, image cubes, and astrophysical narrowband signals that are steady in time. We suggest that the modulation index, along with other statistics using higher order moments, should be incorporated into signal detection pipelines to characterize and classify signals.

Spitler, L. G.; Cordes, J. M.; Chatterjee, S. [Astronomy Department and NAIC, Cornell University, Ithaca, NY 14853 (United States); Stone, J., E-mail: lspitler@astro.cornell.edu [Department of Physics and Astronomy, Barnard College, New York, NY 10027 (United States)

2012-04-01T23:59:59.000Z

353

Spectrum Occupancy Analysis for Cognitive Radio Zhe Wang and Sana Salous  

E-Print Network [OSTI]

Spectrum Occupancy Analysis for Cognitive Radio Zhe Wang and Sana Salous School of Engineering frequency strategy has not been able to optimise the spectrum usage. Cognitive Radio could in theory allow spectrum to operate in. Cognitive Radio would hop into unused bands of the radio spectrum and hop out again

Haddadi, Hamed

354

radioCherenkov.dvi  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

. . Coherent radio Cherenkov radiation detectors: Revised February 2013 by S.R. Klein (LBNL/UC Berkeley) 100 10 10 -4 10 -3 10 -5 1.0 0.1 0.01 E 2 I(E ν ) [GeV m -2 s -1 sr -1 ] E ν [GeV] ν NuMoon 10 9 10 10 10 11 10 12 10 13 10 14 10 15 ATCA (no SSR) ATCA (SSR incl.) RICE ANITA Central GZK ν flux predictions Central GZK ν flux predictions Figure 1: Representative ν flux limits from radio-detection experiments, illustrating the energy ranges for different techniques. Shown are limits from the Rice, ANITA, NuMoon and Lunaska (ATCA) collaborations. NuMoon and Lunaska are low and high frequency lunar scans respectively, showing the strengths of the two different frequency bands. The two limits for ATCA are for different models of the lunar regolith; their separation is a measure of the resultant uncertainty. Also shown, for comparison is the mid-range of flux predictions

355

Analysis Of Factors Affecting Natural Source Slf Electromagnetic  

Open Energy Info (EERE)

Factors Affecting Natural Source Slf Electromagnetic Factors Affecting Natural Source Slf Electromagnetic Exploration At Geothermal Wells Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Analysis Of Factors Affecting Natural Source Slf Electromagnetic Exploration At Geothermal Wells Details Activities (0) Areas (0) Regions (0) Abstract: The Super Low Frequency (SLF) electromagnetic exploration was performed by using a nature source SLF electromagnetic detector at two geothermal wells in Peking University. The data of the SLF electromagnetic exploration at well JR-119 and JR-168 were obtained with the observation of continued five days and four times per day at well JR-119 and of one day at well JR-168. Based on these data, the influencing factors of the SI-F electromagnetic exploration were analyzed, which included the relationship

356

Buoyant radio plasma in clusters of galaxies  

Science Journals Connector (OSTI)

......observing frequency of 330 MHz. In these maps the major...observing frequency is 330 MHz and for the redshift...volume-filling factor of the radio plasma is unity. The units...to note that the hot plasma remains confined within...explosions in the Earth's atmosphere. In their wake the bubbles......

M. Brüggen; C.R. Kaiser

2001-08-01T23:59:59.000Z

357

Radio Frequency Signals in Jupiter's Atmosphere  

Science Journals Connector (OSTI)

...IMAGE OF A LARGE UPWARD ELECTRICAL-DISCHARGE...RINNERT K , HDB ATMOSPHERIC ELEC 27 ( 1995...MEASUREMENTS OF THE RF CHARACTERISTICS...JUPITER PLASMA-WAVE OBSERVATIONS...OBSERVATIONS OF UPPER ATMOSPHERIC OPTICAL FLASHES...Solar and thermal radiation...relatively large at the beginning...and about non-radiative...sensitive area of 6...

L. J. Lanzerotti; K. Rinnert; G. Dehmel; F. O. Gliem; E. P. Krider; M. A. Uman; J. Bach

1996-05-10T23:59:59.000Z

358

Suppression of automotive radio frequency interference  

E-Print Network [OSTI]

'TBATIONS Pag~ 1. Thc Au tomo Li. ve Igni t ion Syst: em 2. Iquivalent Circuit for SLate Variable Analys. i. s 3. Osci. lloscope Presentation of Spar)c P) ug Gap Curron c 77ave form 15 4. k'atbcmat'c. , l Representation of Spark plug ' ap Current t7... ) ? dl. st. r& 0 t * (CD+1) ) & ond. ? d i s tr i. b uior corsducting n==7, 8, . . . 21 ))/?0 n=-7, . . . 2G spark plug not conducCing spar!c plug cor, ducting A suitable computer integration technique may be applied Lo these equati. ons to u...

McLaughlin, Cleon Crosby

1969-01-01T23:59:59.000Z

359

Light modulated switches and radio frequency emitters  

DOE Patents [OSTI]

The disclosure relates to a light modulated electron beam driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

Wilson, Mahlon T. (Los Alamos, NM); Tallerico, Paul J. (Los Alamos, NM)

1982-01-01T23:59:59.000Z

360

Dielectric supported radio-frequency cavities  

DOE Patents [OSTI]

A device which improves the electrical and thermomechanical performance of an RF cavity, for example, in a disk-loaded accelerating structure. A washer made of polycrystalline diamond is brazed in the middle to a copper disk washer and at the outer edge to the plane wave transformer tank wall, thus dissipating heat from the copper disk to the outer tank wall while at the same time providing strong mechanical support to the metal disk. The washer structure eliminates the longitudinal connecting rods and cooling channels used in the currently available cavities, and as a result minimizes problems such as shunt impedance degradation and field distortion in the plane wave transformer, and mechanical deflection and uneven cooling of the disk assembly.

Yu, David U. L. (Rancho Palos Verdes, CA); Lee, Terry G. (Cupertino, CA)

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Recycling for radio astronomy  

Science Journals Connector (OSTI)

......research-article Features Recycling for radio astronomy Melvin Hoare Professor of Astrophysics at the...space missions, carry out single-dish radio astronomy and boost existing radio-astronomy interferometer arrays, objectives that bring......

Melvin Hoare

2012-02-01T23:59:59.000Z

362

Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas  

SciTech Connect (OSTI)

Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (?10{sup 28} m{sup ?3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States)] [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Linscott, Ivan; Strauss, David; Lauben, David [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Srama, Ralf; Mocker, Anna; Bugiel, Sebastian [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)] [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)

2013-09-15T23:59:59.000Z

363

Electromagnetic properties of neutrinos  

E-Print Network [OSTI]

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

Carlo Giunti; Alexander Studenikin

2010-06-08T23:59:59.000Z

364

Electromagnetic Measurements at RHIC  

E-Print Network [OSTI]

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

Hamagaki, Hideki

365

Electromagnetic Measurements at RHIC  

E-Print Network [OSTI]

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

Hamagaki, Hideki

366

Electromagnetic torque analysis of a DFIG for wind turbines  

Science Journals Connector (OSTI)

Electromagnetic torque of doubly fed induction generator (DFIG) is a consequence of the rotor and stator supply. The stator voltage has a fixed amount and frequency. The rotor voltage of the DFIG as a part of a wind turbine has a variable amount and ... Keywords: DFIG, electromagnetic torque, renewable energy, wind turbine

Jurica Smajo; Dinko Vukadinovic

2008-05-01T23:59:59.000Z

367

Electromagnetic space-time crystals. II. Fractal computational approach  

E-Print Network [OSTI]

A fractal approach to numerical analysis of electromagnetic space-time crystals, created by three standing plane harmonic waves with mutually orthogonal phase planes and the same frequency, is presented. Finite models of electromagnetic crystals are introduced, which make possible to obtain various approximate solutions of the Dirac equation. A criterion for evaluating accuracy of these approximate solutions is suggested.

G. N. Borzdov

2014-10-20T23:59:59.000Z

368

Transient electromagnetic interference in substations  

SciTech Connect (OSTI)

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 and electromagnetic models validated against measurements. The nominal maximum field and control wire interference levels expected in the switchyard and inside the control house from switching operations, faults, and an average lightning strike are estimated using high frequency transient coupling models. Comparisons with standards are made and recommendations given concerning equipment shielding and surge protection.

Wiggins, C.M.; Thomas, D.E.; Nickel, F.S.; Salas, T.M. (BDM International, Inc., Albuquerque, NM (United States)); Wright, S.E. (Electric Power Research Inst., Palo Alto, CA (United States))

1994-10-01T23:59:59.000Z

369

E-Print Network 3.0 - account electromagnetic transient Sample...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

crucial points of winding modelling in electromagnetic devices... , a cylindrical magnetizer coil is investigated for low frequency sinusoidal excitation and in a transient......

370

IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 42, NO. 1, FEBRUARY 2000 97 Nonlinear EMI Simulation of an AM Detector at the  

E-Print Network [OSTI]

compatibility and electromagnetic interference (EMC/EMI) simula- tion up to the baseband signal processing path with mea- surements and PSPICE simulation data. Index Terms--AM detector, electromagnetic interference and electromagnetic interference (EMC/EMI) effects on radio systems is increasing significantly. The extensive growth

Loyka, Sergey

371

Wide band stepped frequency ground penetrating radar  

DOE Patents [OSTI]

A wide band ground penetrating radar system (10) embodying a method wherein a series of radio frequency signals (60) is produced by a single radio frequency source (16) and provided to a transmit antenna (26) for transmission to a target (54) and reflection therefrom to a receive antenna (28). A phase modulator (18) modulates those portion of the radio frequency signals (62) to be transmitted and the reflected modulated signal (62) is combined in a mixer (34) with the original radio frequency signal (60) to produce a resultant signal (53) which is demodulated to produce a series of direct current voltage signals (66) the envelope of which forms a cosine wave shaped plot (68) which is processed by a Fast Fourier Transform unit 44 into frequency domain data (70) wherein the position of a preponderant frequency is indicative of distance to the target (54) and magnitude is indicative of the signature of the target (54).

Bashforth, Michael B. (Buellton, CA); Gardner, Duane (Santa Maria, CA); Patrick, Douglas (Santa Maria, CA); Lewallen, Tricia A. (Ventura, CA); Nammath, Sharyn R. (Santa Barbara, CA); Painter, Kelly D. (Goleta, CA); Vadnais, Kenneth G. (Alexandria, VA)

1996-01-01T23:59:59.000Z

372

Quantum modulation against electromagnetic interference  

E-Print Network [OSTI]

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

Juan Carlos Garcia-Escartin

2014-11-26T23:59:59.000Z

373

Electromagnetic partner of the gravitational signal during accretion onto black holes  

E-Print Network [OSTI]

We investigate the generation of electromagnetic and gravitational radiation in the vicinity of a perturbed Schwarzschild black hole. The gravitational perturbations and the electromagnetic field are studied by solving the Teukolsky master equation with sources, which we take to be locally charged, radially infalling, matter. Our results show that, in addition to the gravitational wave generated as the matter falls into the black hole, there is also a burst of electromagnetic radiation. This electromagnetic field has a characteristic set of quasinormal frequencies, and the gravitational radiation has the quasinormal frequencies of a Schwarzschild black hole. This scenario allows us to compare the gravitational and electromagnetic signals that are generated by a common source.

Juan Carlos Degollado; Victor Gualajara; Claudia Moreno; Darío Núñez

2014-10-21T23:59:59.000Z

374

Electromagnetic structure of pion  

SciTech Connect (OSTI)

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

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

2013-03-25T23:59:59.000Z

375

Unbalanced electromagnetic forces  

E-Print Network [OSTI]

) . I :, jazdz g (Member) (Member) August 1974 -" ~ 5:. -. 62 ABSTRACT Unbalanced Electromagnetic Forces (August 1974) Craig Martin Hansen, B. S. , Texas A&M University Directed by: Dr. Attilio J. Giaroia Electromagnetic forces from moving... be deduced from the history of the development of an under- standing of electromagnetic forces. This is a relatively short history (starting in the late 1800's) filled with misunderstandings and pre]udices. This history can be divided into two eras: non...

Hansen, Craig Martin

2012-06-07T23:59:59.000Z

376

Meson electromagnetic form factors  

E-Print Network [OSTI]

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

Stanislav Dubnicka; Anna Z. Dubnickova

2012-10-23T23:59:59.000Z

377

Electron beam induced radio emission from ultracool dwarfs  

E-Print Network [OSTI]

We present the numerical simulations for an electron-beam-driven and loss-cone-driven electron-cyclotron maser (ECM) with different plasma parameters and different magnetic field strengths for a relatively small region and short time-scale in an attempt to interpret the recent discovered intense radio emission from ultracool dwarfs. We find that a large amount of electromagnetic field energy can be effectively released from the beam-driven ECM, which rapidly heats the surrounding plasma. A rapidly developed high-energy tail of electrons in velocity space (resulting from the heating process of the ECM) may produce the radio continuum depending on the initial strength of the external magnetic field and the electron beam current. Both significant linear polarization and circular polarization of electromagnetic waves can be obtained from the simulations. The spectral energy distributions of the simulated radio waves show that harmonics may appear from 10 to 70$\

Yu, S; Kuznetsov, A; Hallinan, G; Antonova, A; MacKinnon, A L; Golden, A

2012-01-01T23:59:59.000Z

378

E-Print Network 3.0 - alcator c-mod radio Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

on Alcator C-Mod Summary: tokamak experiments on Alcator C-Mod. LHCD along with Ion Cyclotron Radio Frequency (ICRF) heating... Commissioning of the Lower Hybrid Current...

379

Observing, modeling and predicting the effects of solar radio bursts on radio communications  

Science Journals Connector (OSTI)

The Sun is a source of broadband radio noise which can reach significantly high levels during outbursts associated with the time evolution of the activity cycle. The statistics point out that the maximum occurrence frequency and intensity of solar radio bursts (SRBs) are observed in the proximity of the activity maximum but relevant phenomena can occur also in the raising and declining phases of the cycle. Both theoretical estimations based on extensive statistical analyses carried out in recent years and direct observations performed in the past solar activity cycle indicate that solar radio bursts can interfere wireless communications as well as Global Navigation Satellite Systems (GNSS). In this work we briefly review the theoretical basis and the experimental evidences to date and we show the effectiveness of fast multichannel solar radiopolarimeters like the Trieste Solar Radio System in monitoring and predicting solar radio noise increase in the framework of Space Weather applications.

Mauro Messerotti

2008-01-01T23:59:59.000Z

380

Discrimination between Jovian radio emissions and Saturn electrostatic discharges  

E-Print Network [OSTI]

vertical streaks in the dynamic spectrum of the Cassini/RPWS (Radio and Plasma Wave Science) receiver in the frequency range of a few MHz can be due to Jovian radio emissions or SEDs (Saturn electrostatic discharges caused by lightning in Saturn's atmosphere. We show a method for discriminating between these two

Gurnett, Donald A.

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Cognitive Radio Networks: How much Spectrum Sharing is Optimal?  

E-Print Network [OSTI]

Cognitive Radio Networks: How much Spectrum Sharing is Optimal? Sudhir Srinivasa and Syed Ali Jafar the traditional `divide and set aside' approach to spectrum regulation ensures that the licensed (primary) users periodically monitors the radio spectrum, intelligently detects occupancy in the different frequency bands

Jafar, Syed A.

382

Tunability enhanced electromagnetic wiggler  

DOE Patents [OSTI]

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.

1992-03-24T23:59:59.000Z

383

Energy Efficient Radio Resource  

E-Print Network [OSTI]

Energy Efficient Radio Resource Management in a Coordinated Multi-Cell Distributed Antenna System Omer HALILOGLU Introduction System Model Performance Evaluation Conclusion References Energy Efficient Hacettepe University 5 September 2014 Omer HALILOGLU (Hacettepe University) Energy Efficient Radio Resource

Yanikomeroglu, Halim

384

Automatic calibration of modulated fractional-N frequency synthesizers  

E-Print Network [OSTI]

The focus of this research has been the development of a low power, radio frequency transmitter architecture. Specifically, a technique for in service automatic calibration of a modulated phase locked loop (PLL) frequency ...

McMahill, Dan

2001-01-01T23:59:59.000Z

385

Radio Research During 1959  

Science Journals Connector (OSTI)

... range of work carried out at the Radio Research Station, Slough, and at the substation in Singapore*.

W. J. G. BEYNON

1961-02-18T23:59:59.000Z

386

Success for radio astronomy  

Science Journals Connector (OSTI)

......August 2000 news News Success for radio astronomy Jim Cohen of Jodrell Bank Observatory...mm-wave spectrum. As a result, radio astronomy is now officially allocated most of the...International Mobile Telecommunications). Radio astronomy made its gains in the mm-wave region......

Jim Cohen

2000-08-01T23:59:59.000Z

387

Auction-based Agent Negotiation in Cognitive Radio Ad Hoc Networks  

E-Print Network [OSTI]

of spectrum. To solve the problem of congestion, cognitive radio networks use dynamic spectrum access spectrum access. 1 Introduction The Cognitive Radio (CR) is a form of wireless communication in which are not and can move to unused channels. This optimizes the use of available radio frequency spectrum while

388

Prediction of Channel State for Cognitive Radio Using Higher-Order Hidden Markov Model  

E-Print Network [OSTI]

-- Spectrum sensing detects the availability of the radio frequency spectrum, which is essential and vital to cognitive radio. Traditional techniques for spectrum sensing fail to take the latency between spectrum spectrum. It introduces "intelligence" beyond software defined radio (SDR). Spectrum sensing (SS

Qiu, Robert Caiming

389

IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS PART B 1 Spectrum Sharing in Cognitive Radio Networks  

E-Print Network [OSTI]

IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS ­ PART B 1 Spectrum Sharing in Cognitive Radio of radio frequency spectrum. In this paper, we consider the problem of spectrum sharing among primary (or Terms--Cognitive radio, spectrum sensing, spectrum sharing, game theory, Nash equilibrium. I

Wang, Xinbing

390

CONTROL OF JOVIAN RADIO EMISSIONS BY THE GALILEAN MOONS AS OBSERVED BY  

E-Print Network [OSTI]

CONTROL OF JOVIAN RADIO EMISSIONS BY THE GALILEAN MOONS AS OBSERVED BY CASSINI AND GALILEO G. B can control a portion of the Jovian radio emission. More recent studies using the Galileo and Voyager­frequency Jovian decametric radio (DAM) emission. The Cassini gravity­assist flyby of Jupiter on December 30, 2000

Gurnett, Donald A.

391

Determination, Control & Improvement of an SKA Radio  

E-Print Network [OSTI]

SKA core sites were chosen in a sparsely populated part of South Africa, in the Northern Cape ProvinceDetermination, Control & Improvement of an SKA Radio Environment in South Africa Three potential -200 -150 -100 -50 0 Frequency spectrum 150 to 174 MHz Spectralpowerflux-density Agg Signal Kalahari

Ellingson, Steven W.

392

I. What is electromagnetic radiation and the electromagnetic spectrum?  

E-Print Network [OSTI]

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

Sitko, Michael L.

393

Underground radio technology saves miners and emergency response personnel  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Underground radio technology saves miners and emergency response Underground radio technology saves miners and emergency response personnel Underground radio technology saves miners and emergency response personnel Founded through LANL, Vital Alert Technologies, Inc. (Vital Alert) has launched a wireless, two-way real-time voice communication system that is effective through 1,000+ feet of solid rock. April 3, 2012 Vital Alert's C1000 mine and tunnel radios use magnetic induction, advanced digital communications techniques and ultra-low frequency transmission to wirelessly provide reliable 2-way voice, text, or data links through rock strata and other solid media. Vital Alert's C1000 mine and tunnel radios use magnetic induction, advanced digital communications techniques and ultra-low frequency transmission to wirelessly provide reliable 2-way voice, text, or data links through rock

394

Interpretation of electromagnetic soundings in the Raft River geothermal  

Open Energy Info (EERE)

Interpretation of electromagnetic soundings in the Raft River geothermal Interpretation of electromagnetic soundings in the Raft River geothermal area, Idaho Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Interpretation of electromagnetic soundings in the Raft River geothermal area, Idaho Details Activities (1) Areas (1) Regions (0) Abstract: An electromagnetic (EM) controlled source survey was conducted in the Raft River Valley, near Malta, Idaho. The purpose of the survey was: to field test U.S. Geological Survey extra-low-frequency (ELF) equipment using a grounded wire source and receiver loop configuration (which is designed to measure the vertical magnetic field (Hz) at the loop center for various frequencies); to present an example of the EM sounding data and interpretations using a previously developed inversion program; and (3) to

395

Electromagnetic Soundings At Raft River Geothermal Area (1977) | Open  

Open Energy Info (EERE)

Electromagnetic Soundings At Raft River Geothermal Area (1977) Electromagnetic Soundings At Raft River Geothermal Area (1977) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Electromagnetic Soundings At Raft River Geothermal Area (1977) Exploration Activity Details Location Raft River Geothermal Area Exploration Technique Electromagnetic Sounding Techniques Activity Date 1977 Usefulness not indicated DOE-funding Unknown Exploration Basis The purpose of the survey was: (1) to field test U.S. Geological Survey extra-low-frequency (ELF) equipment using a grounded wire source and receiver loop configuration (which is designed to measure the vertical magnetic field (Hz) at the loop center for various frequencies); (2) to present an example of the EM sounding data and interpretations using a

396

Asia Pacific Symposium of Applied Electromagnetics and Mechanics (APSAEM2010) Kuala Lumpur, Malaysia, 28-30th  

E-Print Network [OSTI]

, Malaysia, 28-30th July 2010 Reducing Electromagnetic Interference in Non-Isolated DC to DC Step JAMALUDIN*2 Investigation of the Electromagnetic interference (EMI) is important for design of a good power: electromagnetic interference, power converter, EMI, ohmic heating, high frequency. 1. Introduction In order

Hammerton, James

397

Purely electromagnetic spacetimes  

E-Print Network [OSTI]

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

B. V. Ivanov

2007-12-15T23:59:59.000Z

398

Electromagnetic rotational actuation.  

SciTech Connect (OSTI)

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

Hogan, Alexander Lee

2010-08-01T23:59:59.000Z

399

Self-consistent electrodynamics of large-area high-frequency capacitive plasma discharge  

SciTech Connect (OSTI)

Capacitively coupled plasmas (CCPs) generated using high frequency (3-30 MHz) and very high frequency (30-300 MHz) radio-frequency (rf) sources are used for many plasma processing applications including thin film etching and deposition. When chamber dimensions become commensurate with the effective rf wavelength in the plasma, electromagnetic wave effects impose a significant influence on plasma behavior. Because the effective rf wavelength in plasma depends upon both rf and plasma process conditions (e.g., rf power and gas pressure), a self-consistent model including both the rf power delivery system and the plasma discharge is highly desirable to capture a more complete physical picture of the plasma behavior. A three-dimensional model for self-consistently studying both electrodynamic and plasma dynamic behavior of large-area (Gen 10, >8 m{sup 2}) CCP is described in this paper. This model includes Maxwell's equations and transport equations for charged and neutral species, which are coupled and solved in the time domain. The complete rf plasma discharge chamber including the rf power delivery subsystem, rf feed, electrodes, and the plasma domain is modeled as an integrated system. Based on this full-wave solution model, important limitations for processing uniformity imposed by electromagnetic wave propagation effects in a large-area CCP (3.05x2.85 m{sup 2} electrode size) are studied. The behavior of H{sub 2} plasmas in such a reactor is examined from 13.56 to 200 MHz. It is shown that various rectangular harmonics of electromagnetic fields can be excited in a large-area rectangular reactor as the rf or power is increased. The rectangular harmonics can create not only center-high plasma distribution but also high plasma density at the corners and along the edges of the reactor.

Chen Zhigang; Rauf, Shahid; Collins, Ken [Applied Materials, Inc., 974 E. Arques Avenue, Sunnyvale, California 94085 (United States)

2010-10-15T23:59:59.000Z

400

Gradient instabilities of electromagnetic waves in Hall thruster plasma  

SciTech Connect (OSTI)

This paper presents a linear analysis of gradient plasma instabilities in Hall thrusters. The study obtains and analyzes the dispersion equation of high-frequency electromagnetic waves based on the two-fluid model of a cold plasma. The regions of parameters corresponding to unstable high frequency modes are determined and the dependence of the increments and intrinsic frequencies on plasma parameters is obtained. The obtained results agree with those of previously published studies.

Tomilin, Dmitry [Department of Electrophysics, Keldysh Research Centre, Moscow 125438 (Russian Federation)

2013-04-15T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Radio Observations of High Redshift Radio Galaxies  

E-Print Network [OSTI]

We review some aspects of radio continuum polarimetric imaging of high redshift radio galaxies. The correlation between extreme values of Faraday rotation observed toward radio emitting structures in nearby radio galaxies, and X-ray emitting cluster atmospheres, is presented as a method for targeting objects at high redshift for deep X-ray searches. We present an X-ray detection of the extreme rotation measure radio galaxy PKS 1138-262 at z = 2.156, and we argue that the X-ray emission is from a cluster atmosphere with a luminosity of 1.7x10^{44} h^{-2} ergs sec^{-1}. We also present results on the correlation between size and redshift for a sample of ultra-luminous radio galaxies between 0 < z < 4.3. Source sizes decrease systematically with redshift, suggesting either denser environments, or younger sources, at high redshift. An alternative explanation is significant inverse Compton losses off the microwave background at high redshift.

C. L. Carilli; H. J. A. Rottgering; G. K. Miley L. Pentericci; D. E. Harris

1998-02-18T23:59:59.000Z

402

Discovery of a Radio Flare from GRB 990123  

E-Print Network [OSTI]

We report the discovery of a radio counterpart to GRB 990123. In contrast to previous well-studied radio afterglows which rise to peak flux on a timescale of a week and then decay over several weeks to months, the radio emission from this GRB was clearly detected one day after the burst, after which it rapidly faded away. The simplest interpretation of this ``radio flare'' is that it arises from the reverse shock. In the framework of the afterglow models discussed to date, a forward shock origin for the flare is ruled out by our data. However, at late times, some radio afterglow emission (commensurate with the observed late-time optical emission, the optical afterglow) is expected from the forward shock. The relative faintness of the observed late-time radio emission provides an independent indication for a jet-like geometry in this GRB. We use the same radio observations to constrain two key parameters of the forward shock, peak flux and peak frequency, to within a factor of two. These values are inconsistent with the notion advocated by several authors that the prompt optical emission detected by ROTSE smoothly joins the optical afterglow emission. Finally, with hindsight we now recognize another such radio flare and this suggests that one out of eight GRBs has a detectable radio flare. This abundance coupled with the reverse shock interpretation suggests that the radio flare phenomenon has the potential to shed new light into the physics of reverse shocks in GRBs.

S. R. Kulkarni; D. A. Frail; R. Sari; G. H. Moriarty-Schieven; D. S. Shepherd; P. Udomprasert; A. C. S. Readhead; J. S. Bloom; M. Feroci; E. Costa

1999-03-30T23:59:59.000Z

403

EIA Radio test  

U.S. Energy Information Administration (EIA) Indexed Site

September 10, 2012 September 10, 2012 Test of Energy News Radio Service This is a test audio file of the U.S. Energy Information Administration's energy news radio service to be launched on Tuesday, September 11 th with the release of EIA's monthly Short-Term Energy Outlook. EIA's radio service will provide free short broadcast stories on EIA energy data reports and analysis to radio stations nationwide. The stories will be recorded in MP3 format and can be downloaded from EIA's radio service webpage at www.eia.gov/radio. The first broadcast stories will be posted around noon Eastern Time on Sept. 11 after the release of EIA's monthly Short Term Energy Outlook forecast. These initial stories will focus on the outlook for U.S. gasoline prices, crude oil production and natural gas production.

404

ON THE EVOLUTION OF THE CORES OF RADIO SOURCES AND THEIR EXTENDED RADIO EMISSION  

SciTech Connect (OSTI)

The work in this paper aims at determining the evolution and possible co-evolution of radio-loud active galactic nuclei (AGNs) and their cores via their radio luminosity functions (i.e., total and core RLFs, respectively). Using a large combined sample of 1063 radio-loud AGNs selected at low radio frequency, we investigate the RLF at 408 MHz of steep-spectrum radio sources. Our results support a luminosity-dependent evolution. Using core flux density data of the complete sample 3CRR, we investigate the core RLF at 5.0 GHz. Based on the combined sample with incomplete core flux data, we also estimate the core RLF using a modified factor of completeness. Both results are consistent and show that the comoving number density of radio cores displays a persistent decline with redshift, implying a negative density evolution. We find that the core RLF is obviously different from the total RLF at the 408 MHz band which is mainly contributed by extended lobes, implying that the cores and extended lobes could not be co-evolving at radio emission.

Yuan Zunli; Wang Jiancheng, E-mail: yuanzunli@ynao.ac.cn [National Astronomical Observatories, Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)

2012-01-10T23:59:59.000Z

405

EMG #121471 Electromagnetics, 25:679693, 2005  

E-Print Network [OSTI]

. Keywords electromagnetic compatibility, electromagnetic interference, aperture, cou- pling, finite compatibility (EMC) and electromagnetic interference (EMI) requirements, it is crucial to quantify

Ramahi, Omar

406

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

E-Print Network [OSTI]

walls and tubes) and with strong EMI (Electromagnetic Interference). So it is ideal to use the power

Paris-Sud XI, Université de

407

618 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 49, NO. 3, JUNE 2002 A Comparative Study of Carrier-Frequency  

E-Print Network [OSTI]

-frequency modulation (CFM) techniques for the conducted electromagnetic interference (EMI) suppression in pulsewidth. The most direct way of solving electromagnetic interference (EMI) problems is to reduce the emission from

So, Hing-Cheung

408

Telecommunications Radio Lease  

E-Print Network [OSTI]

Telecommunications Radio Lease 1. Fax completed form to 979.847.1111. 2. If you do not receive to any of the radios, chargers and accessories until signed back over to the Telecommunications office Telecommunications Office Use Only Service Due Date Installation Cost (NRC) Billed To Telephone/Circuit Number

409

Telecommunications Radio Rental  

E-Print Network [OSTI]

Telecommunications Radio Rental 1. Fax completed form to 979.847.1111. 2. If you do not receive of the radios, chargers and accessories until signed back over to the Telecommunications office. Amount Work Order Prepared Departmental Approval Signature Date Service Date Desired Telecommunications Office

410

Smart Radio Spectrum Management for Cognitive Radio  

E-Print Network [OSTI]

Today's wireless networks are characterized by fixed spectrum assignment policy. The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. Cognitive radio is a paradigm for wireless communication in which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently avoiding interference with licensed or unlicensed users. In this work, a fuzzy logic based system for spectrum management is proposed where the radio can share unused spectrum depending on some parameters like distance, signal strength, node velocity and availability of unused spectrum. The system is simulated and is found to give satisfactory results.

Bhattacharya, Partha Pratim; Gera, Rishita; Agarwal, Anjali

2011-01-01T23:59:59.000Z

411

Televisions, Video Privacy, and Powerline Electromagnetic Interference  

E-Print Network [OSTI]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv Safe Use Guidelines, Electromagnetic Interference, and FCC Warning . . . . . . . . . . . . .v

Matsuoka, Yoky

412

Electromagnetic Radiation REFERENCE: Remote Sensing of  

E-Print Network [OSTI]

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

Gilbes, Fernando

413

Electromagnetically Induced Flows Michiel de Reus  

E-Print Network [OSTI]

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

Vuik, Kees

414

8.07 Electromagnetism II, Fall 2005  

E-Print Network [OSTI]

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

Bertschinger, Edmund

415

Cognitive Radio will revolutionize American transportation  

ScienceCinema (OSTI)

Cognitive Radio will revolutionize American transportation. Through smart technology, it will anticipate user needs; detect available bandwidths and frequencies then seamlessly connect vehicles, infrastructures, and consumer devices; and it will support the Department of Transportation IntelliDrive Program, helping researchers, auto manufacturers, and Federal and State officials advance the connectivity of US transportation systems for improved safety, mobility, and environmental conditions. Using cognitive radio, a commercial vehicle will know its driver, onboard freight and destination route. Drivers will save time and resources communicating with automatic toll booths and know ahead of time whether to stop at a weigh station or keep rolling. At accident scenes, cognitive radio sensors on freight and transportation modes can alert emergency personnel and measure on-site, real-time conditions such as a chemical leak. The sensors will connect freight to industry, relaying shipment conditions and new delivery schedules. For industry or military purposes, cognitive radio will enable real-time freight tracking around the globe and its sensory technology can help prevent cargo theft or tampering by alerting shipper and receiver if freight is tampered with while en route. For the average consumer, a vehicle will tailor the transportation experience to the passenger such as delivering age-appropriate movies via satellite. Cognitive radio will enhance transportation safety by continually sensing what is important to the user adapting to its environment and incoming information, and proposing solutions that improve mobility and quality of life.

None

2013-12-06T23:59:59.000Z

416

Cognitive Radio will revolutionize American transportation  

SciTech Connect (OSTI)

Cognitive Radio will revolutionize American transportation. Through smart technology, it will anticipate user needs; detect available bandwidths and frequencies then seamlessly connect vehicles, infrastructures, and consumer devices; and it will support the Department of Transportation IntelliDrive Program, helping researchers, auto manufacturers, and Federal and State officials advance the connectivity of US transportation systems for improved safety, mobility, and environmental conditions. Using cognitive radio, a commercial vehicle will know its driver, onboard freight and destination route. Drivers will save time and resources communicating with automatic toll booths and know ahead of time whether to stop at a weigh station or keep rolling. At accident scenes, cognitive radio sensors on freight and transportation modes can alert emergency personnel and measure on-site, real-time conditions such as a chemical leak. The sensors will connect freight to industry, relaying shipment conditions and new delivery schedules. For industry or military purposes, cognitive radio will enable real-time freight tracking around the globe and its sensory technology can help prevent cargo theft or tampering by alerting shipper and receiver if freight is tampered with while en route. For the average consumer, a vehicle will tailor the transportation experience to the passenger such as delivering age-appropriate movies via satellite. Cognitive radio will enhance transportation safety by continually sensing what is important to the user adapting to its environment and incoming information, and proposing solutions that improve mobility and quality of life.

None

2013-07-22T23:59:59.000Z

417

Electromagnetic Field Theory  

E-Print Network [OSTI]

physicists around the world and from WWW `hit' statistics it seems that the book serves as a frequently used formulation of classical electrodynamics, force, momentum and energy of the electromagnetic field, radiation and scope to make it useful in higher university education anywhere in the world, it was produced within

Hart, Gus

418

Electromagnetic Wave Dynamics in  

E-Print Network [OSTI]

possibilities for strong localization of electromagnetic radiation in a dense and ultracold atomic gas sample an ultracold atomic rubidium gas sample, showing the coherent backscattering cone. The angular width of electrical excita- tion of condensed samples.3 Ongoing experimental and theoretical research directed toward

419

Electromagnetism and Gravitation  

E-Print Network [OSTI]

The classical concept of "mass density" is not fundamental to the quantum theory of matter. Therefore, mass density cannot be the source of gravitation. Here, we treat electromagnetic energy, momentum, and stress as its source. The resulting theory predicts that the gravitational potential near any charged elementary particle is many orders of magnitude greater than the Newtonian value.

Kenneth Dalton

1997-03-10T23:59:59.000Z

420

Electromagnetic pulsar spindown  

E-Print Network [OSTI]

We evaluate the result of the recent pioneering numerical simulations in Spitkovsky~2006 on the spindown of an oblique relativistic magnetic dipole rotator. Our discussion is based on our experience from two idealized cases, that of an aligned dipole rotator, and that of an oblique split-monopole rotator. We conclude that the issue of electromagnetic pulsar spindown may not have been resolved yet.

I. Contopoulos

2007-01-10T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

A method for calculating wide band electromagnetic interference from power line corona  

SciTech Connect (OSTI)

An algorithm for calculating electromagnetic interference from power line corona for a range of frequencies from 100 kHz to 30 MHz is demonstrated. It can be used for calculations at any distance or direction from the line. The algorithm incorporates an existing generation function which has been optimized by comparison to long term electromagnetic interference measurements.

Olsen, R.G. [Washington State Univ., Pullman, WA (United States). School of Electrical Engineering and Computer Science] [Washington State Univ., Pullman, WA (United States). School of Electrical Engineering and Computer Science; Schennum, S.D. [Gonzaga Univ., Spokane, WA (United States)] [Gonzaga Univ., Spokane, WA (United States)

1995-07-01T23:59:59.000Z

422

E-Print Network 3.0 - accurate frequency dependent Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

-induced errors. TRINAV synergistically combines the use of GPS with a ground-based radio-frequency (RF) ... Source: Pennycook, Steve - Materials Science and Technology...

423

The spectral structure and energetics of powerful radio sources  

E-Print Network [OSTI]

Determining the energy spectrum of an electron population can give key insights into the underlying physics of a radio source; however, the lack of high resolution, broad-bandwidth observations has left many ambiguities in our understanding of radio galaxies. The improved capabilities of telescopes such as the JVLA and LOFAR mean that within the bandwidth of any given observation, a detailed spectral shape can now be produced. We present recent investigations of powerful FR-II radio galaxies at GHz and MHz frequencies and show for the first time their small-scale spectral structure. We highlight problems in traditional methods of analysis and demonstrate how these issues can now be addressed. We present the latest results from low frequency studies which suggest a potential increase in the total energy content of radio galaxy lobes with possible implications for the energetics of the population as a whole.

Harwood, J J; Croston, J H; Stroe, A; Morganti, R; Orru, E

2014-01-01T23:59:59.000Z

424

Computational Electronics and Electromagnetics  

SciTech Connect (OSTI)

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.

1993-03-01T23:59:59.000Z

425

Particle acceleration in double radio sources  

Science Journals Connector (OSTI)

Further study has been made of a model of extragalactic double radio sources in which the magnetized accretion disc of a massive black hole acts as an electric dynamo producing oppositely directed beams of relativistic particles. An empty region of small angular size—a vortice core—is shown to be a possible consequence of the hydrodynamics of accretion of gas with angular momentum. An ambient magnetic field in the gas tends to accumulate in the core region. The acceleration of electrons in the dynamo electric field gives rise to oppositely directed electron beams which in turn produce synchroton gamma rays collimated along the core. Collisions between the gamma rays and low energy photons caN initiate an electromagnetic cascade shower. The cascade acts to produce a collimated relativistic electron?positron beam. If the current flow in the dynamo occurs in surges then the outward propagation of the head of the electron–positron beams may produce expanding compact radio components. The electron–positron beam is ballistic in nature and it is electrically neutral and carries no current. Such a beam appears to have favorable stability properties. The beam is eventually stopped and spread out in pitch angle by the ram pressure of the external medium. Synchrotron radiated lobes of double radio sources.

R. V. E. Lovelace; J. MacAuslan; M. Burns

1979-01-01T23:59:59.000Z

426

MEASURING THE JET POWER OF FLAT-SPECTRUM RADIO QUASARS  

SciTech Connect (OSTI)

We use frequency-dependent position shifts of flat-spectrum radio cores to estimate the kinetic power of active galactic nucleus (AGN) jets. We find a correlation between the derived jet powers and AGN narrow-line luminosity, consistent with the well-known relation for radio galaxies and steep spectrum quasars. This technique can be applied to intrinsically weak jets even at high redshift.

Shabala, S. S.; Santoso, J. S. [School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, TAS 7001 (Australia); Godfrey, L. E. H. [International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845 (Australia)

2012-09-10T23:59:59.000Z

427

ON THE EXISTENCE OF 'RADIO THERMALLY ACTIVE' GALACTIC SUPERNOVA REMNANTS  

SciTech Connect (OSTI)

In this paper, we investigate the possibility of significant production of thermal bremsstrahlung radiation at radio continuum frequencies that could be linked to some Galactic supernova remnants (SNRs). The main targets for this investigation are SNRs expanding in high-density environments. There are several indicators of radio thermal bremsstrahlung radiation from SNRs, such as a flattening at higher frequencies and thermal absorption at lower frequencies intrinsic to an SNR. In this work, we discuss the radio continuum properties of three SNRs that are the best candidates for testing our hypothesis of significant thermal emission. In the case of SNRs IC 443 and 3C 391, thermal absorption has been previously detected. For IC 443, the contribution of thermal emission at 1 GHz, from our model fit is 3%-57%. It is similar to the estimate obtained from the thermal absorption properties (10%-40% at 1 GHz). In the case of the 3C 391 the conclusions are not so clear. The results from our model fit (thermal emission contribution of 10%-25% at 1 GHz) and results obtained from the low-frequency absorption (thermal contribution of 0.15%-7% at 1 GHz) do not overlap. For the SNR 3C 396 we suggest that if previously detected thermal absorption could be intrinsic to the SNR then the thermal emission (<47% at 1 GHz from our model fit) could be significant enough to shape the radio continuum spectrum at high frequencies. Polarization observations for these SNRs can constrain the strength of a thermal component. Reliable observations at low frequencies (<100 MHz) are needed as well as more data at high radio frequencies (>1 GHz), in order to make stronger conclusions about the existence of 'radio thermally active' SNRs.

Onic, D.; Urosevic, D.; Arbutina, B. [Department of Astronomy, Faculty of Mathematics, University of Belgrade (Serbia); Leahy, D. [Department of Physics and Astronomy, University of Calgary (Canada)

2012-09-01T23:59:59.000Z

428

Low Cost Radio Telescope  

Science Journals Connector (OSTI)

A radio interferometer has been constructed at Haverford College as an aid to learning the fundamentals of radio astronomy. Its cost both in cash outlay and in construction time make it a feasible year-long project for an undergraduate. Its simplicity does not prevent it from being a useful instrument for instruction at the college or high-school level; among its capabilities are the measurement of the positions of at least four of the strongest discrete cosmic-noisesources and the diameter of the radio sun.

Joseph H. Taylor Jr.

1964-01-01T23:59:59.000Z

429

Vibration Isolation using a Shunted Electromagnetic S. Behrens, A. J. Fleming, S. O. R. Moheimani  

E-Print Network [OSTI]

a base disturbance y. A low- frequency mass-spring-damper is often employed as a mechanical filter to the terminals of an electromagnetic coil, the relative mechanical velocity between the coil and magnet can

Fleming, Andrew J.

430

A Survey on Dynamic Spectrum Access Techniques for Cognitive Radio  

E-Print Network [OSTI]

Cognitive radio (CR) is a new paradigm that utilizes the available spectrum band. The key characteristic of CR system is to sense the electromagnetic environment to adapt their operation and dynamically vary its radio operating parameters. The technique of dynamically accessing the unused spectrum band is known as Dynamic Spectrum Access (DSA). The dynamic spectrum access technology helps to minimize unused spectrum bands. In this paper, main functions of Cognitive Radio (CR) i.e. spectrum sensing, spectrum management, spectrum mobility and spectrum sharing are discussed. Then DSA models are discussed along with different methods of DSA such as Command and Control, Exclusive-Use, Shared Use of Primary Licensed User and Commons method. Game-theoretic approach using Bertrand game model, Markovian Queuing Model for spectrum allocation in centralized architecture and Fuzzy logic based method are also discussed and result are shown.

Garhwal, Anita

2012-01-01T23:59:59.000Z

431

CRAF Handbook for Radio Astronomy  

E-Print Network [OSTI]

CRAF Handbook for Radio Astronomy EUROPEAN SCIENCE FOUNDATION Committee on Radio Astronomy. It represents all scientific disciplines: physical and engineering sciences, life, earth and environmental Handbook for Radio Astronomy, 3rd edition". #12;CRAF Handbook for Radio Astronomy Edited by Jim Cohen

Rodriguez, Luis F.

432

Banded electromagnetic stator core  

DOE Patents [OSTI]

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1996-01-01T23:59:59.000Z

433

Banded electromagnetic stator core  

DOE Patents [OSTI]

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1994-01-01T23:59:59.000Z

434

Gravitation and Electromagnetism  

E-Print Network [OSTI]

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

B. G. Sidharth

2001-06-16T23:59:59.000Z

435

Fractional Electromagnetic Waves  

E-Print Network [OSTI]

In the present work we consider the electromagnetic wave equation in terms of the fractional derivative of the Caputo type. The order of the derivative being considered is 0 <\\gamma<1. A new parameter \\sigma, is introduced which characterizes the existence of the fractional components in the system. We analyze the fractional derivative with respect to time and space, for \\gamma = 1 and \\gamma = 1/2 cases.

J. F. Gómez; J. J. Rosales; J. J. Bernal; V. I. Tkach; M. Guía

2011-08-31T23:59:59.000Z

436

Quaternion Gravi-Electromagnetism  

E-Print Network [OSTI]

Defining the generalized charge, potential, current and generalized fields as complex quantities where real and imaginary parts represent gravitation and electromagnetism respectively, corresponding field equation, equation of motion and other quantum equations are derived in manifestly covariant manner. It has been shown that the field equations are invariant under Lorentz as well as duality transformations. It has been shown that the quaternionic formulation presented here remains invariant under quaternion transformations.

A. S. Rawat; O. P. S. Negi

2011-07-05T23:59:59.000Z

437

Banded electromagnetic stator core  

DOE Patents [OSTI]

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

1996-06-11T23:59:59.000Z

438

Banded electromagnetic stator core  

DOE Patents [OSTI]

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

1994-04-05T23:59:59.000Z

439

The Impact of Frequency-Agility on Dynamic Spectrum Sharing  

E-Print Network [OSTI]

The Impact of Frequency-Agility on Dynamic Spectrum Sharing Lili Cao, Lei Yang and Haitao Zheng}@cs.ucsb.edu Abstract-- Designed to adapt spectrum usage on-the-fly, frequency-agile radios can drastically improve complexity. This motivates us to understand when and why having higher degree of frequency-agility helps

Almeroth, Kevin C.

440

Generalized Terminal Modeling of Electromagnetic Interference  

SciTech Connect (OSTI)

Terminal models have been used for various applications. In this paper, a three-terminal model is proposed for electromagnetic-interference (EMI) characterization. The model starts with a power electronic system at a particular operating condition and creates a unique linearized equivalent circuit. Impedances and current/voltage sources define the noise throughout the entire EMI frequency spectrum. All parameters needed to create the model are clearly defined to ensure convergence and maximize accuracy. In addition, the accuracy of the model is confirmed up to 100 MHz for a dc-dc boost converter using both simulation and experimental validation.

Baisden, Andrew Carson [IEEE Industrial Applications Society; Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech); Wang, Fei [ORNL

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Bursty synchrotron intensity variations of Jovian 6-cm radio emissions and Jupiter's quasi-periodic polar activities  

Science Journals Connector (OSTI)

......low-frequency (nu 0.7 MHz) beamed radio bursts...low-frequency (nu 0.7 MHz) beamed radio bursts...observations (10-20 kHz) of Ulysses during...polar field lines and plasmas (Halekas et al...bandwidth of 100-490 MHz and an antenna efficiency...measurements for atmospheric effects and the antenna......

Yu-Qing Lou; Huagang Song; Yinyu Liu; Meng Yang

2012-03-01T23:59:59.000Z

442

Quantum mechanical constraints on the measurement of the density of the electromagnetic energy  

E-Print Network [OSTI]

It is considered constraints imposed by the quantum mechanics on the measurement of the density of the electromagnetic energy. First, the energy of the electromagnetic wave and the volume (time) are bound with the Heisenberg uncertainty principle. It reduces from double to ordinary the relativistic effect for the density of the electromagnetic energy. Second, the frequency of photons and the number of photons are bound with the Heisenberg uncertainty principle. Then relativistic effects for the frequency of photons and for the number of photons are incompatible.

D. L. Khokhlov

2004-02-05T23:59:59.000Z

443

ELECTROMAGNETIC COMPATIBILITY AND RENEWABLE POWER FOR IMPLANTABLE NEUROSTIMULATORS  

E-Print Network [OSTI]

J, Bakker P: Electromagnetic interference from radiomaking electromagnetic interference neurostimulator functioninclude electromagnetic interference and battery failure. In

Pantchenko, Oxana S.

2012-01-01T23:59:59.000Z

444

Electromagnetic analysis of nanostructure dispersion in polymer matrices  

E-Print Network [OSTI]

P. R. , “Enhanced electromagnetic interference shielding40] Chung D. D. L. “Electromagnetic Interference Shieldingreinforcement, electromagnetic interference shielding, etc.

Pfeifer, Steven Charles; Pfeifer, Steven Charles

2012-01-01T23:59:59.000Z

445

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

E-Print Network [OSTI]

Electromagnetic WavesElectromagnetic Waves In this chapter we will review selected properties of electromagnetic waves since radar involves the transmission, propagation and scattering of EM waves by various is the electrostatic force between two point charges. #12;Electromagnetic WavesElectromagnetic Waves Electric fields

Rutledge, Steven

446

Monitoring i n s i t u retorting processes of oil shale by reflected and transmitted electromagnetic waves  

Science Journals Connector (OSTI)

A theoretical model for an i n s i t u oil shale retort with three distinct vertical zones all surrounded by a wall of oil shale overburden and underburden is considered for the study of potential electromagnetic monitoring of the progression of retorting processes using wave propagation techniques. The overall power reflection and transmission coefficients for both transverse electric and transverse magnetic waves are used for finding the position of a combustion zone in the retort based upon the assumption of straight?line propagation of monochromatic plane waves through layered lossy dielectric media characterized by the dielectric constants and loss tangents. The behavior of each power coefficient is discussed as a function of burn front positions and signal frequencies. As a result of the relatively moderate signal power for each coefficient required for detection and the one?to?one correspondence between each power coefficient and burn front position at typical conditions the feasibility of using low radio?frequency waves to monitor relatively large scale i n s i t u retorting process is established.

S. H. Hong; J. B. DuBow

1980-01-01T23:59:59.000Z

447

Radio and Spectrum Management | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

Radio and Spectrum Management Radio and Spectrum Management DOE Radio and Spectrum Workshop 43.pdf More Documents & Publications ICAM Workshop Ad Hoc Meetings Spectrum Technology...

448

Cognitive Radio Networks as Sensor Networks  

E-Print Network [OSTI]

is used, assuming the cognitive radios know their ownfor Embedded Networked Sensing Cognitive Radio Networks AsJ. Pottie Introduction: Cognitive Radio (CR) Networks The

Bandari, Dorna; Yang, Seung R.; Zhao, Yue; Pottie, Gregory

2007-01-01T23:59:59.000Z

449

E-Print Network 3.0 - astrosphere collapse frequency Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

First, mon- itor the low-frequency heliospheric radio emissions. Second, survey plasma waves... of daily averaged higher frequency fluctuations up to 0.25 Hz over 16 min...

450

Radio Receiver Design  

Science Journals Connector (OSTI)

... local oscillator and then through the intermediate-frequency amplifier to the second detector giving an audio-frequency output. The present volume ends at this stage, leaving ... -frequency output. The present volume ends at this stage, leaving audio-frequency amplifiers and power supplies to be dealt with in Part 2. ...

1943-06-12T23:59:59.000Z

451

Electromagnetic induction in accelerated conductors  

Science Journals Connector (OSTI)

Boundary conditions are derived for the interfaces of a conductor moving across an external magnetic field in an ambient medium (vacuum or nonconductor), which consider the emission of electromagnetic waves from the conductor surface as a result of electromagnetic induction. These boundary conditions are applied to the initial-boundary-value problem for the electromagnetic induction in a conducting slab, which is accelerated across a homogeneous magnetic field to a nonrelativistic velocity. Fourier-series solutions are presented for the transient electromagnetic fields in the moving conductor and the discontinuous electromagnetic waves in the ambient space. It is shown that the transient electromagnetic fields inside and outside the conductor are due to two mechanisms, i.e., "velocity induction" (ordinary induction) and "acceleration induction" [dv?(t)dt?0?]. The latter result cannot be explained by means of the Lorentz transformation, which is valid only for constant conductor velocities (inertial frames).

H. E. Wilhelm

1982-06-01T23:59:59.000Z

452

A Leviathan Takes Shape Beneath Geneva's Gentle Environs  

Science Journals Connector (OSTI)

...universe. The long view. A string of superconducting...electromagnetic fields oscillating at radio frequencies...universe. The long view. A string of superconducting...electromagnetic fields oscillating at radio frequencies...

Matin Durrani

2004-02-06T23:59:59.000Z

453

Torsion and the Electromagnetic Field  

E-Print Network [OSTI]

In the framework of the teleparallel equivalent of general relativity, we study the dynamics of a gravitationally coupled electromagnetic field. It is shown that the electromagnetic field is able not only to couple to torsion, but also, through its energy-momentum tensor, to produce torsion. Furthermore, it is shown that the coupling of the electromagnetic field with torsion preserves the local gauge invariance of Maxwell's theory.

V. C. de Andrade; J. G. Pereira

1999-01-11T23:59:59.000Z

454

Electromagnetic field and cosmic censorship  

E-Print Network [OSTI]

We construct a gedanken experiment in which an extremal Kerr black hole interacts with a test electromagnetic field. Using Teukolsky's solutions for electromagnetic perturbations in Kerr spacetime, and the conservation laws imposed by the energy momentum tensor of the electromagnetic field and the Killing vectors of the spacetime, we prove that this interaction cannot convert the black hole into a naked singularity, thus cosmic censorship conjecture is not violated in this case.

Koray Düzta?

2014-04-09T23:59:59.000Z

455

Electromagnetism on Anisotropic Fractals  

E-Print Network [OSTI]

We derive basic equations of electromagnetic fields in fractal media which are specified by three indepedent fractal dimensions {\\alpha}_{i} in the respective directions x_{i} (i=1,2,3) of the Cartesian space in which the fractal is embedded. To grasp the generally anisotropic structure of a fractal, we employ the product measure, so that the global forms of governing equations may be cast in forms involving conventional (integer-order) integrals, while the local forms are expressed through partial differential equations with derivatives of integer order but containing coefficients involving the {\\alpha}_{i}'s. First, a formulation based on product measures is shown to satisfy the four basic identities of vector calculus. This allows a generalization of the Green-Gauss and Stokes theorems as well as the charge conservation equation on anisotropic fractals. Then, pursuing the conceptual approach, we derive the Faraday and Amp\\`ere laws for such fractal media, which, along with two auxiliary null-divergence conditions, effectively give the modified Maxwell equations. Proceeding on a separate track, we employ a variational principle for electromagnetic fields, appropriately adapted to fractal media, to independently derive the same forms of these two laws. It is next found that the parabolic (for a conducting medium) and the hyperbolic (for a dielectric medium) equations involve modified gradient operators, while the Poynting vector has the same form as in the non-fractal case. Finally, Maxwell's electromagnetic stress tensor is reformulated for fractal systems. In all the cases, the derived equations for fractal media depend explicitly on fractal dimensions and reduce to conventional forms for continuous media with Euclidean geometries upon setting the dimensions to integers.

Martin Ostoja-Starzewski

2011-06-08T23:59:59.000Z

456

Spectrally efficient hybrid multiplexing and demultiplexing schemes toward the integration of microwave and millimeter-wave radio-over-fiber systems in a WDM-PON infrastructure  

Science Journals Connector (OSTI)

Hybrid multiplexing and demultiplexing schemes with the capability to integrate microwave and millimeter-wave frequency radio-over-fiber signals in a wavelength division multiplexed...

Bakaul, Masuduzzaman; Nirmalathas, Ampalavanapillai; Lim, Christina; Novak, Dalma; Waterhouse, Rod

2009-01-01T23:59:59.000Z

457

Electromagnetic Probes in PHENIX  

E-Print Network [OSTI]

Electromagnetic probes are arguably the most universal tools to study the different physics processes in high energy hadron and heavy ion collisions. In this paper we summarize recent measurements of real and virtual direct photons at central rapidity by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au collisions. We also discuss the impact of the results and the constraints they put on theoretical models. At the end we report on the immediate as well as on the mid-term future of photon measurements at RHIC.

Gabor David

2006-09-21T23:59:59.000Z

458

Gravitation and electromagnetism  

E-Print Network [OSTI]

Maxwell's equations comprise both electromagnetic and gravitational fields. The transverse part of the vector potential belongs to magnetism, the longitudinal one is concerned with gravitation. The Coulomb gauge indicates that longitudinal components of the fields propagate instantaneously. The delta-function singularity of the field of the divergence of the vector potential, referred to as the dilatation center, represents an elementary agent of gravitation. Viewing a particle as a source or a scattering center of the point dilatation, the Newton's gravitation law can be reproduced.

V. P. Dmitriyev

2002-07-23T23:59:59.000Z

459

Electromagnetic pump stator coil  

DOE Patents [OSTI]

An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

Fanning, A.W.; Dahl, L.R.

1996-06-25T23:59:59.000Z

460

The diffuse radio emission around NGC 5580 and NGC 5588  

E-Print Network [OSTI]

The galaxy pair NGC 5580 and NGC 5588 are part of a loose group of galaxies. They are surrounded by steep-spectrum, extended radio emission which was previously suggested to be a down-scaled example of Mpc-size radio haloes present in galaxies clusters. We present a multi-frequency study of the radio-emission aimed to clarify its nature. The source has been observed with the Giant Meterwave Radio Telescope at 235, 325 and 610 MHz and the images obtained were combined with archival data to cover the frequency range 150-1400 MHz. The new observations revealed the presence of a second, fainter lobe on the South-East of NGC 5580. The spectral index study of the source shows a flattening of the spectrum (which implies a younger particle population) close to the two galaxies. We argue that the extended radio emission is the remnant of a past activity cycle of the active galactic nucleus present in NGC 5580 and therefore a notable example of a dying radio galaxy located outside a dense environments.

de Gasperin, F; Williams, W; Brüggen, M; Murgia, M; Beck, R; Bonafede, A

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Beam dynamics studies for transverse electromagnetic mode type rf deflectors  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

We have performed three-dimensional simulations of beam dynamics for transverse electromagnetic mode (TEM) type rf deflectors: normal and superconducting. The compact size of these cavities as compared to the conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of six 2-cell normal conducting cavities or a single cell superconducting structure is enough to produce the required vertical displacement at the target point. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.

Ahmed, Shahid; Krafft, Geoffrey A.; Deitrick, Kirsten; De Silva, Subashini U.; Delayen, Jean R.; Spata, Mike; Tiefenback, Michael; Hofler, Alicia; Beard, Kevin

2012-02-01T23:59:59.000Z

462

Statistics of the electromagnetic response of a chaotic reverberation chamber  

E-Print Network [OSTI]

This article presents a study of the electromagnetic response of a chaotic reverberation chamber (RC) in the presence of losses. By means of simulations and of experiments, the fluctuations in the maxima of the field obtained in a conventional mode-stirred RC are compared with those in a chaotic RC in the neighborhood of the Lowest Useable Frequency (LUF). The present work illustrates that the universal spectral and spatial statistical properties of chaotic RCs allow to meet more adequately the criteria required by the Standard IEC 61000-4-21 to perform tests of electromagnetic compatibility.

J. -B. Gros; U. Kuhl; O. Legrand; F. Mortessagne; O. Picon; E. Richalot

2014-09-20T23:59:59.000Z

463

Ion cyclotron range of frequencies heating of plasma with small impurity production  

DOE Patents [OSTI]

Plasma including plasma ions is magnetically confined by a magnetic field. The plasma has a defined outer surface and is intersected by resonance surfaces of respective common ion cyclotron frequency of a predetermined species of plasma ions moving in the magnetic field. A radio frequency source provides radio frequency power at a radio frequency corresponding to the ion cyclotron frequency of the predetermined species of plasma ions moving in the field at a respective said resonance surface. RF launchers coupled to the radio frequency source radiate radio frequency energy at the resonance frequency onto the respective resonance surface within the plasma from a plurality of locations located outside the plasma at such respective distances from the intersections of the respective resonance surface and the defined outer surface and at such relative phases that the resulting interference pattern provides substantially null net radio frequency energy over regions near and including substantial portions of the intersections relative to the radio frequency energy provided thereby at other portions of the respective resonance surface within the plasma.

Ohkawa, Tihiro (La Jolla, CA)

1987-01-01T23:59:59.000Z

464

Fast Neighbor Discovery with Lightweight Termination Detection in Heterogeneous Cognitive Radio Networks  

E-Print Network [OSTI]

the congestion within the frequency spectrum. A cognitive radio transceiver can operate over a wide range of the spectrum that the CR node can operate on may be allocated to licensed users who are known as primary usersFast Neighbor Discovery with Lightweight Termination Detection in Heterogeneous Cognitive Radio

Mittal, Neeraj

465

Effects of Bit Allocation on Non-contiguous Multicarrier-based Cognitive Radio Transceivers  

E-Print Network [OSTI]

of the licensed spectrum is relatively un- used across time and frequency [1]. Nevertheless, current regu- latory flexibility and access to spectrum. To exploit the advantages of cognitive radio transceivers and enableEffects of Bit Allocation on Non-contiguous Multicarrier-based Cognitive Radio Transceivers

Kansas, University of

466

Graph-based Criteria for Spectrum-Aware Clustering in Cognitive Radio Milan Bradonjica, Loukas Lazosb,  

E-Print Network [OSTI]

Graph-based Criteria for Spectrum-Aware Clustering in Cognitive Radio Networks Milan Bradonji, Arizona Email: llazos@ece.arizona.edu Abstract Cognitive radios (CRs) can exploit vacancies in licensed. 1. Introduction Under a fixed spectrum allocation paradigm, frequency bands are licensed

Lazos, Loukas

467

Uplink Cell Capacity of Cognitive Radio Networks with Peak Interference Power Constraints  

E-Print Network [OSTI]

.wang@hw.ac.uk.john.thompson@ed.ac.uk Abstract-A cognitive radio (secondary) network can reuse the under-utilized spectrum licensed to a primary. I. INTRODUCTION The radio spectrum is a precious natural resource that underpins various wireless frequency bands to license holders for exclusive use. Such a static spectrum licensing policy eliminates

Wang, Cheng-Xiang

468

Z mode waves as the source of Saturn narrowband radio emissions  

E-Print Network [OSTI]

Z mode waves as the source of Saturn narrowband radio emissions ShengYi Ye,1 J. D. Menietti,1 G emissions observed by the Cassini Radio and Plasma Waves Science (RPWS) instrument during high latitude perikrone passes. The narrowband emissions observed below the local electron cyclotron frequency ( fce

Gurnett, Donald A.

469

Electromagnetic fuel injector  

SciTech Connect (OSTI)

This patent describes an electromagnetic fuel injector for an internal combustion engine having a valve axis and including a housing, a flat armature connected to a movable valve element arranged to cooperate with a valve seat, spring means for exerting a force in an axial direction on the armature, and electromagnetic means for exerting a force in an opposite direction on the armature when electrically energized. The improvement comprises: the spring means being a helical coil spring disposed in substantially coaxial alignment with the valve axis and having an end in compressive engagement with the armature, the final coil which includes the end of the coil spring being inclined axially outward at an angle relative to a plane normal to the axis of the spring so as to apply to the armature a greater axial spring force to one side of the valve axis than the other thereby to effect pivoting of the armature about a pivot, the pivot being determined by the location of the end of the coil spring.

Gieseking, J.H.

1987-04-28T23:59:59.000Z

470

Spectrum Management for Cognitive Radio based on Genetics Algorithm  

E-Print Network [OSTI]

Spectrum scarceness is one of the major challenges that the present world is facing. The efficient use of existing licensed spectrum is becoming most critical as growing demand of the radio spectrum. Different researches show that the use of licensed are not utilized inefficiently. It has been also shown that primary user does not use more than 70% of the licensed frequency band most of the time. Many researchers are trying to found the techniques that efficiently utilize the under-utilized licensed spectrum. One of the approaches is the use of "Cognitive Radio". This allows the radio to learn from its environment, changing certain parameters. Based on this knowledge the radio can dynamically exploit the spectrum holes in the licensed band of the spectrum. This paper w i l l focus on the performance of spectrum allocation technique, based on popular meta-heuristics Genetics Algorithm and analyzing the performance of this technique using Mat Lab.

Singh, Santosh Kumar; Pathak, Vibhakar; Roy, Dr Krishna Chandra

2011-01-01T23:59:59.000Z

471

Special Presentation: Key Findings from the Barrier Immune Radio  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Special Presentation: Key Findings from the Barrier Immune Radio Special Presentation: Key Findings from the Barrier Immune Radio Communications Project Speaker(s): Francis Rubinstein Girish Ghatikar Peter Haugen Date: November 29, 2007 - 12:00pm Location: 90-3122 The Barrier Immune Radio Communications (BIRC) Project was established in January 2007 by the Demand Response Emerging Technologies Program (DRETD) to identify radio frequency technologies that could enable the widespread deployment of Demand Response strategies in buildings. Researchers from Lawrence Berkeley National Laboratory and Lawrence Livermore National Laboratory will present the key findings from this project in a one-hour presentation. Researchers found that several of the RF technologies tested at LBNL's Molecular Foundry building were able to provide sufficiently

472

Controlled Source Frequency-Domain Electromagnetics At Neal Hot...  

Open Energy Info (EERE)

efforts. Software provided by Zonge International was used for the interpretation process. Interpretations show that the production fault dips west and trends north-south and...

473

Low Frequency Electromagnetic Fields in High Contrast Media ?  

E-Print Network [OSTI]

ow monitoring, in underground contaminant detection, etc. In this paper we will focus attention, such as hydrocarbons, are poor conductors in comparison with other pore liquids, such as brines [4, 33]. Thus

Papanicolaou, George C.

474

Low Frequency Electromagnetic Fields in High Contrast Media ?  

E-Print Network [OSTI]

flow monitoring, in underground contaminant detection, etc. In this paper we will focus attention, such as hydrocarbons, are poor conductors in comparison with other pore liquids, such as brines [4, 33]. Thus

Borcea, Liliana

475

Anomalous electron heat transport driven by low frequency electromagnetic turbulence  

SciTech Connect (OSTI)

We consider the anomalous electron and heat transport in a tokamak plasma. The electrons are described by the nonlinear drift-kinetic equation. We analyze transport through the averaged response function in the presence of drift-Alfven wave turbulence. In contrast to recent findings by Terry, Diamond, and Hahm, we conclude that magnetic fluctuations lead to a substantial transport of both parallel and perpendicular energies. The latter, previously neglected, is found to be significant and of the order of the test-particle diffusion.

Thoul, A.A.; Similon, P.L.; Sudan, R.N.

1987-09-28T23:59:59.000Z

476

Electromagnetics in characterizations  

E-Print Network [OSTI]

(cont.) Characterization of the differential guided mode of a coupled-strip transmission line allows us to understand its behaviors in high frequency circuit applications. S-parameters of the differential mode of a ...

Wu, Bae-Ian, 1975-

2003-01-01T23:59:59.000Z

477

Electromagnetic Radiation in Accelerated Systems  

Science Journals Connector (OSTI)

A generally covariant set of electromagnetic field equations and associated constitutive relations is developed to deal with electromagnetic radiation in arbitrarily moving media. The equations are sufficiently general to include dispersive as well as nonisotropic media. Several special cases are investigated to illustrate the method and to demonstrate the consistency of the formulation.

J. L. Anderson and J. W. Ryon

1969-05-25T23:59:59.000Z

478

Electromagnetic neutrino: a short review  

E-Print Network [OSTI]

A short review on selected issues related to the problem of neutrino electromagnetic properties is given. After a flash look at the theoretical basis of neutrino electromagnetic form factors, constraints on neutrino magnetic moments and electric millicharge from terrestrial experiments and astrophysical observations are discussed. We also focus on some recent studies of the problem and on perspectives.

Alexander I. Studenikin

2014-11-09T23:59:59.000Z

479

Cognitive Radio: Fundamentals and Opportunities  

E-Print Network [OSTI]

Cognitive Radio: Fundamentals and Opportunities Robert H. Morelos-Zaragoza Department of Electrical Engineering San Jose State University October 12, 2007 #12;Cognitive Radio - RHMZ - 2007 Slide 2 of 18 Outline. Cognitive radio (CR) a) Definition and overview (Mitola) b) CR features (FCC) 3. Unlicensed TV spectrum

Morelos-Zaragoza, Robert H.

480

Electronics, Radio and Telecommunications  

Science Journals Connector (OSTI)

... a grant-in-aid from the United States National Science Foundation. One of these is Telecommunications (No. 1, 1957. Pp. 1-94. First English issue. Issued in ... the official publication of the A. S. Popov Technical Society of Radio Engineering and Telecommunications. ...

1958-10-11T23:59:59.000Z

Note: This page contains sample records for the topic "radio frequency electromagnetic" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481