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Note: This page contains sample records for the topic "rf radio frequency" from the National Library of EnergyBeta (NLEBeta).
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1

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.

2

Radio frequency (RF) heated supersonic flow laboratory  

SciTech Connect

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

3

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

4

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

5

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…

6

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

SciTech Connect

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

7

Influence of the Radio-Frequency source properties on RF-based atom traps  

Science Journals Connector (OSTI)

We discuss the quality required for the RF source used to trap neutral atoms in RF-dressed potentials. We illustrate this discussion with experimental results obtained on a Bose-Einstein condensation experimen...

O. Morizot; L. Longchambon; R. Kollengode Easwaran…

2008-04-01T23:59:59.000Z

8

Microwave (MW) and Radio Frequency (RF) as Enabling Technologies for Advanced Manufacturing  

Energy.gov (U.S. Department of Energy (DOE))

Purpose, Context, Meeting Process, and Agenda for MW and RF as Enabling Technologies for Advanced Manufacturing on July 25, 2012

9

An overview of the Low Energy Demonstration Accelerator (LEDA) project RF (radio frequency) systems  

SciTech Connect

Successful operation of the Accelerator Production of Tritium (APT) plant will require that accelerator downtime be kept to an absolute minimum. Over 230 separate 1 MW RF systems are expected to be used in the APT plant, making the efficiency and reliability of these systems two of the most critical factors in plant operation. The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for APT. The design of the RF systems used in LEDA has been driven by the need for high efficiency and extremely high system reliability. The authors present details of the high voltage power supply and transmitter systems as well as detailed descriptions of the waveguide layout between the klystrons and the accelerating cavities. The first stage of LEDA operations will use four 1.2 MW klystrons to test the RFQ and supply power to one test stand. The RFQ will serve as a power combiner for multiple RF systems. They present some of the unique challenges expected in the use of this concept.

Bradley, J. III; Cummings, K.; Lynch, M.; Rees, D.; Roybal, W.; Tallerico, P. [Los Alamos National Lab., NM (United States); Toole, L. [Savannah River Site, SC (United States)

1997-05-12T23:59:59.000Z

10

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

11

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

12

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

13

Nano-fabricated superconducting radio-frequency composites, method for producing nano-fabricated superconducting rf composites  

DOE Patents (OSTI)

Superconducting rf is limited by a wide range of failure mechanisms inherent in the typical manufacture methods. This invention provides a method for fabricating superconducting rf structures comprising coating the structures with single atomic-layer thick films of alternating chemical composition. Also provided is a cavity defining the invented laminate structure.

Norem, James H.; Pellin, Michael J.

2013-06-11T23:59:59.000Z

14

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

15

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

16

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

17

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

18

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

19

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

20

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

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

22

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

23

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

24

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

25

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.

26

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

27

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

28

Microwave and Radio Frequency Workshop  

Energy.gov (U.S. Department of Energy (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 ...

29

Frequency and amplitude control for an experimental linac rf drive  

E-Print Network (OSTI)

, India Chair of Advisory Committee: Dr. S. P. Bhattacharyya, The Texas Accelerator Center (TAC) experimental linear accelerator uses a radio- frequency quadrupole (RFQ) to accelerate a 10 mA beam of H ions to 500 keV. It is to be used as an injector... to form a high-energy input beam for large circular accelerators. The pulsed beam will require 100 kW peak rf power at 473 MHz. To satisfy the beam dynamics requirements for particle acceleration and to minimize beam spill, the frequency of the source...

Atre, Mahesh Purushottam

1992-01-01T23:59:59.000Z

30

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

31

Effect of radio frequency discharge power on dusty plasma parameters  

SciTech Connect

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

32

Extremely high frequency RF effects on electronics.  

SciTech Connect

The objective of this work was to understand the fundamental physics of extremely high frequency RF effects on electronics. To accomplish this objective, we produced models, conducted simulations, and performed measurements to identify the mechanisms of effects as frequency increases into the millimeter-wave regime. Our purpose was to answer the questions, 'What are the tradeoffs between coupling, transmission losses, and device responses as frequency increases?', and, 'How high in frequency do effects on electronic systems continue to occur?' Using full wave electromagnetics codes and a transmission-line/circuit code, we investigated how extremely high-frequency RF propagates on wires and printed circuit board traces. We investigated both field-to-wire coupling and direct illumination of printed circuit boards to determine the significant mechanisms for inducing currents at device terminals. We measured coupling to wires and attenuation along wires for comparison to the simulations, looking at plane-wave coupling as it launches modes onto single and multiconductor structures. We simulated the response of discrete and integrated circuit semiconductor devices to those high-frequency currents and voltages, using SGFramework, the open-source General-purpose Semiconductor Simulator (gss), and Sandia's Charon semiconductor device physics codes. This report documents our findings.

Loubriel, Guillermo Manuel; Vigliano, David; Coleman, Phillip Dale; Williams, Jeffery Thomas; Wouters, Gregg A.; Bacon, Larry Donald; Mar, Alan

2012-01-01T23:59:59.000Z

33

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

34

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

35

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

36

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

37

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

38

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

39

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.

40

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

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

42

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

SciTech Connect

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

43

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

44

Energy Saving Glass Lamination via Selective Radio-Frequency Heating  

SciTech Connect

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

45

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

46

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

47

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

48

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

SciTech Connect

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

49

Upgrading EMMA to Use Low-frequency RF Cavities  

SciTech Connect

EMMA is an experiment to study beam dynamics in fixed field alternating gradient accelerators (FFAGs). It accelerates the beam in about 10 turns using 1.3 GHz cavities in a mode like that used for muon accelerators. Many applications of FFAGs prefer to have slower acceleration, typically thousands of turns. To do so in EMMA would require the RF system to be replaced with a low-frequency, high-gradient system. This paper describes the motivation for studying slow acceleration in EMMA and the required parameters for an RF system to do that. It then describes the technology needed for the RF system.

Ohmori, C.; Berg, J.

2011-04-30T23:59:59.000Z

50

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

51

Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators  

SciTech Connect

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

52

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

SciTech Connect

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

53

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

54

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

55

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

SciTech Connect

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

56

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

SciTech Connect

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

57

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

58

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

59

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

60

A Parametric Study of Electron Extraction from a Low Frequency Inductively Coupled RF-Plasma Source  

E-Print Network (OSTI)

: The electron extraction from a low-frequency (2 MHz) inductively-coupled rf-plasma cathode is characterizedA Parametric Study of Electron Extraction from a Low Frequency Inductively Coupled RF-Plasma Source and rf-plasma source, rf-power and xenon gas flow. The results demonstrate that the electron supply from

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61

Response of radio frequency superconducting quantum interference devices to electromagnetic interference  

SciTech Connect

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

62

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

SciTech Connect

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

63

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

SciTech Connect

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

64

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

65

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

SciTech Connect

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

66

Radio-frequency plasma transducer for use in harsh environments  

SciTech Connect

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

67

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

68

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

SciTech Connect

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

69

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect

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

70

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect

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

71

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

72

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

73

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

74

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

75

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.

76

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

77

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

78

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

SciTech Connect

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

79

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

SciTech Connect

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

80

Energy Saving Glass Lamination via Selective Radio Frequency Heating  

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

H- radio frequency source development at the Spallation Neutron Source  

SciTech Connect

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

82

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

83

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

SciTech Connect

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

84

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

SciTech Connect

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

85

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

SciTech Connect

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

86

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

87

Radio-frequency stabilization of a nonequilibrium plasma accelerator  

SciTech Connect

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

88

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

89

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

90

Low-frequency RF Coupling To Unconventional (Fat Unbalanced) Dipoles  

SciTech Connect

The report explains radio frequency (RF) coupling to unconventional dipole antennas. Normal dipoles have thin equal length arms that operate at maximum efficiency around resonance frequencies. In some applications like high-explosive (HE) safety analysis, structures similar to dipoles with ''fat'' unequal length arms must be evaluated for indirect-lightning effects. An example is shown where a metal drum-shaped container with HE forms one arm and the detonator cable acts as the other. Even if the HE is in a facility converted into a ''Faraday cage'', a lightning strike to the facility could still produce electric fields inside. The detonator cable concentrates the electric field and carries the energy into the detonator, potentially creating a hazard. This electromagnetic (EM) field coupling of lightning energy is the indirect effect of a lightning strike. In practice, ''Faraday cages'' are formed by the rebar of the concrete facilities. The individual rebar rods in the roof, walls and floor are normally electrically connected because of the construction technique of using metal wire to tie the pieces together. There are two additional requirements for a good cage. (1) The roof-wall joint and the wall-floor joint must be electrically attached. (2) All metallic penetrations into the facility must also be electrically connected to the rebar. In this report, it is assumed that these conditions have been met, and there is no arcing in the facility structure. Many types of detonators have metal ''cups'' that contain the explosives and thin electrical initiating wires, called bridge wires mounted between two pins. The pins are connected to the detonator cable. The area of concern is between the pins supporting the bridge wire and the metal cup forming the outside of the detonator. Detonator cables usually have two wires, and in this example, both wires generated the same voltage at the detonator bridge wire. This is called the common-mode voltage. The explosive component inside a detonator is relatively sensitive, and any electrical arc is a concern. In a safety analysis, the pin-to-cup voltage, i.e., detonator voltage, must be calculated to decide if an arc will form. If the electric field is known, the voltage between any two points is simply the integral of the field along a line between the points. Eq. 1.1. For simplicity, it is assumed that the electric field and dipole elements are aligned. Calculating the induced detonator voltage is more complex because of the field concentration caused by metal components. If the detonator cup is not electrically connected to the metal HE container, the portion of the voltage generated by the dipole at the detonator will divide between the container-to-cup and cup-to-pin gaps. The gap voltages are determined by their capacitances. As a simplification, it will be assumed the cup is electrically attached, short circuited, to the HE container. The electrical field in the pin-to-cup area is determined by the field near the dipole, the length of the dipole, the shape of the arms, and the orientation of the arms. Given the characteristics of a lightning strike and the inductance of the facility, the electric fields in the ''Faraday cage'' can be calculated. The important parameters for determining the voltage in an empty facility are the inductance of the rebars and the rate of change of the current, Eq. 1.3. The internal electric fields are directly related to the facility voltages, however, the electric fields in the pin-to-cup space is much higher than the facility fields because the antenna will concentrate the fields covered by the arms. Because the lightning current rise-time is different for every strike, the maximum electric field and the induced detonator voltage should be described by probability distributions. For pedantic purposes, the peak field in the simulations will be simply set to 1 V/m. Lightning induced detonator voltages can be calculated by scaling up with the facility fields. Any metal object around the explosives, such as a work stand, will also distort the electric

Ong, M M; Brown, C G; Perkins, M P; Speer, R D; Javedani, J B

2010-12-07T23:59:59.000Z

91

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

92

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

93

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

94

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

95

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

SciTech Connect

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

96

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

97

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

98

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

99

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

SciTech Connect

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

100

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

102

Novel rf mems tunable filters with adjustable spurious suppression  

E-Print Network (OSTI)

This thesis presents the theory and design of fixed and Radio Frequency (RF) Microelectromechanical Systems (MEMS) -based tunable microwave filters for RF and microwave applications. The methodology for the design of coupled resonator filters...

Sekar, Vikram

2009-05-15T23:59:59.000Z

103

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

SciTech Connect

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

104

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

105

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

106

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

107

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

108

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

109

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

110

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

111

Particle-In-Cell/Monte Carlo Simulation of Ion Back BomBardment in a High Average Current RF Photo-Gun  

E-Print Network (OSTI)

High Average Current RF Photo-Gun J. Qiang Lawrence Berkeleycurrent radio-frequency (RF) photo-gun using a particle-in-of high average current RF photo-guns have been proposed or

Qiang, J.

2010-01-01T23:59:59.000Z

112

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

113

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

114

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

115

Radio frequency overview of the high explosive radio telemetry project  

SciTech Connect

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

116

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

117

Verification of particle simulation of radio frequency waves in fusion plasmas  

SciTech Connect

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

118

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

SciTech Connect

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

119

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

SciTech Connect

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

120

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

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

122

rf Plasma Heating in a Mirror Machine at Frequencies near the Ion Cyclotron Frequency and its Harmonics  

Science Journals Connector (OSTI)

By applying 75 kW of pulsed rf power to a decaying hydrogen plasma following turbulent heating, we have maintained a plasma density of 1012 to 5 × 1012 cm-3 for the 600-? sec duration of the rf pulse. Neutral energy analyzer measurements of ion temperature indicate Ti?100 eV, while diamagnetic loop measurements indicate 100 eVrf signals near the harmonics of the ion cyclotron frequency.

D. G. Swanson; R. W. Clark; P. Korn; S. Robertson; C. B. Wharton

1972-04-17T23:59:59.000Z

123

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

SciTech Connect

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

124

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

125

Dual radio frequency plasma source: Understanding via electrical asymmetry effect  

SciTech Connect

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

126

Method and Apparatus for Pasteurizing Shell Eggs Using Radio Frequency  

NLE Websites -- All DOE Office Websites (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

127

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

128

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

SciTech Connect

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

129

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

SciTech Connect

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

130

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

SciTech Connect

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

131

rf  

NLE Websites -- All DOE Office Websites (Extended Search)

RF RF It's what makes the protons go 'round. The latest in a series explaining particle physics in everyday language. Painless Physics Articles BEAM COOLING August 2, 1996 By Leila Belkora, Office of Public Affairs ACCELERATION August 16, 1996 By Dave Finley, Accelerator Division Head RF August 30, 1996 By Pat Colestock, Accelerator Division FIXED TARGET PHYSICS September 20, 1996 By Peter H. Garbincius, Physics Section FIXED TARGET PHYSICS PART DEUX October 16, 1996 By Peter H. Garbincius, Physics Section and Leila Belkora, Office of Public Affaris CROSS SECTION November 1, 1996 By Doreen Wackeroth, Theoretical Physics Edited by Leila Belkora, Office of Public Affaris MAGNETS PART I November 15, 1996 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs

132

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

133

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

134

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

SciTech Connect

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

135

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

136

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

137

"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

138

Frequency-feedback tuning for single-cell cavity under rf heating  

SciTech Connect

A tuning system is described that is being used to match the source frequency of a high-power klystron on the resonant frequency of the prototype single-cell cavity for the 7-GeV Advance Photon Source (APS) storage ring. Typically a water-cooled piston tuner is required to adjust the reactive component of the cavity`s impedance to minimize reflected power back to the RF drive source. As the cavity watts expand due to RF heating, the resonant frequency decreases. Adjusting the source frequency to follow the cavity resonant frequency is a convenient method used to condition the cavity (for vacuum) at high power levels, in this case, 1 MV gap voltage at 100 kW power level. The tuning system consists of two coupling ports, a phase detector, a digitizing I/O system, and a DC coupled FM-modulated RF source. Proportional Integral Derivative (PID) loop parameters for the Experimental Physics and Industrial Control System (EPICS) software are calculated, and data is presented showing the damped response to peturbations on the loop. The timing system presented here does not need water-cooling, has no moving parts to wear out, and has an inherently faster response time. Its one limitation is the digitizing sampling rate. The only limitation in tuning range is the bandwidth of the RF source.

Stepp, J.D.; Bridges, J.F.

1993-08-01T23:59:59.000Z

139

ION HEATING WITH RF FIELDS NEAR THE ION CYCLOTRON FREQUENCY J. D. Barter, J. C. Sprott  

E-Print Network (OSTI)

ION HEATING WITH RF FIELDS NEAR THE ION CYCLOTRON FREQUENCY by J. D. Barter, J. C. Sprott November. Our experiments of the past year, however, indicate that ion cyclotron resonance heating transmitted without consent of the author and major professor. #12;For several years we have been heating ions

Sprott, Julien Clinton

140

Magnetic field probes for use in radio frequency plasma  

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

The splitting of hyperfine lines of57Fe nuclei in RF magnetic field  

Science Journals Connector (OSTI)

It is shown experimentally, that for Moessbauer nuclei affected by the radio-frequency (RF) magnetic field of sufficient intensity at frequencies corresponding to ... occurs. Depending on the frequency of alterna...

F. G. Vagizov

1990-08-01T23:59:59.000Z

142

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

SciTech Connect

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

143

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

SciTech Connect

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

144

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

145

Coupling effects in inductive discharges with radio frequency substrate biasing  

SciTech Connect

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

146

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

147

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

148

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

149

Longitudinal capture in the radio-frequency-quadrupole structure  

SciTech Connect

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

150

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

SciTech Connect

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

151

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

152

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

153

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

SciTech Connect

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

154

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

SciTech Connect

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

155

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

156

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

157

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

SciTech Connect

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

158

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

159

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

SciTech Connect

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

160

Multi-frequency aluminum nitride micro-filters for advanced RF communications.  

SciTech Connect

An AlN MEMS resonator technology has been developed, enabling massively parallel filter arrays on a single chip. Low-loss filter banks covering the 10 MHz--10-GHz frequency range have been demonstrated, as has monolithic integration with inductors and CMOS circuitry. The high level of integration enables miniature multi-bandm spectrally aware, and cognitive radios.

Nordquist, Christopher Daniel; Stevens, James E.; Olsson, Roy H., III; Wojciechowski, Kenneth E.; Tuck, Melanie R.

2010-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" 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

Radio-frequency stabilization of a nonequilibrium plasma accelerator  

Science Journals Connector (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 suppre...

K. P. Kirdyashev

2011-08-01T23:59:59.000Z

162

A plasma cathode for a radio-frequency gun  

Science Journals Connector (OSTI)

A plasma ferroelectric cathode is used to form electron ... high charge in an electron bunch in an rf electron gun of a 10-cm wavelength ... . The operation of the cathode in the rf gun was studied experimentally...

V. A. Kushnir; I. V. Khodak

2008-09-01T23:59:59.000Z

163

Excitation frequency effects on atmospheric-pressure helium RF microplasmas: plasma density, electron energy and plasma impedance  

Science Journals Connector (OSTI)

...The effects of the driving RF frequency on the properties of low temperature atmospheric pressure helium microplasmas are discussed in light...?...m microdischarge driven at constant input power with a 10 MHz–...

K. McKay; F. Iza; M. G. Kong

2010-12-01T23:59:59.000Z

164

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

SciTech Connect

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

165

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

166

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

SciTech Connect

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

167

E-Print Network 3.0 - accurate frequency dependent Sample Search...  

NLE Websites -- All DOE Office Websites (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...

168

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

169

Optical Patch Antennas - Analysis and Design inspired by Radio Frequency  

Science Journals Connector (OSTI)

Optical antennas have been quite instrumental in manipulating light in subwavelength scales. Considering their significant resemblance to RF counterparts, computational tools of patch...

Unal, Gul Seda; Aksun, M Irsadi

170

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

171

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

SciTech Connect

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

172

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

173

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

174

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

175

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

176

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

SciTech Connect

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

177

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

178

Radio Frequency Diesel Particulate Filter Sensor Reduces Fuel...  

Office of Environmental Management (EM)

this process, known as regeneration, to only occur when needed, thereby reducing fuel consumption and enabling longer filter life. The RF-DPF can be used with light- and...

179

Radio-frequency quadrupole vane-tip geometries  

SciTech Connect

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

180

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

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

SciTech Connect

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

182

Radio frequency discharge with control of plasma potential distribution  

SciTech Connect

A RF discharge plasma generator with additional electrodes for independent control of plasma potential distribution is proposed. With positive biasing of this ring electrode relative end flanges and longitudinal magnetic field a confinement of fast electrons in the discharge will be improved for reliable triggering of pulsed RF discharge at low gas density and rate of ion generation will be enhanced. In the proposed discharge combination, the electron energy is enhanced by RF field and the fast electron confinement is improved by enhanced positive plasma potential which improves the efficiency of plasma generation significantly. This combination creates a synergetic effect with a significantly improving the plasma generation performance at low gas density. The discharge parameters can be optimized for enhance plasma generation with acceptable electrode sputtering.

Dudnikov, Vadim [Muons, Inc., Batavia, Illinois 60510 (United States); Dudnikov, A. [BINP, Novosibirsk 63090 (Russian Federation)

2012-02-15T23:59:59.000Z

183

Surface plasma source with saddle antenna radio frequency plasma generator  

SciTech Connect

A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

Dudnikov, V.; Johnson, R. P. [Muons, Inc., Batavia, Illinios 60510 (United States); Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R. [ORNL, Oak Ridge, Tennessee 37831 (United States)

2012-02-15T23:59:59.000Z

184

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 55, NO. 4, APRIL 2007 1193 Frequency Tunable Microstrip Patch Antenna Using RF  

E-Print Network (OSTI)

Microstrip Patch Antenna Using RF MEMS Technology Emre Erdil, Kagan Topalli, Mehmet Unlu, Ozlem Aydin Civi, and Tayfun Akin Abstract--A novel reconfigurable microstrip patch antenna is presented that is monolithically. Reconfigurability of the operating frequency of the microstrip patch antenna is achieved by loading

Akin, Tayfun

185

The Emergence of RF-Powered Computing  

Science Journals Connector (OSTI)

Extracting power "from thin air" has a quality of science fiction about it, yet technology trends make it likely that in the near future, small computers in urban areas will use ambient RF signals for both power and communication. The first Web extra ... Keywords: Backscatter,RF signals,Radio frequency,Computers,Telemetry,TV,Power distribution,Wireless communication,Ubiquitous computing,emerging technologies,wireless communication,ubiquitous computing

Shyamnath Gollakota, Matthew Reynolds, Joshua Smith, David Wetherall

2014-01-01T23:59:59.000Z

186

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

NLE Websites -- All DOE Office Websites (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....

187

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

188

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

189

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

190

Towards Optimization of Probe Placement for Radio-Frequency Ablation  

E-Print Network (OSTI)

's electric potential and of the steady state of the heat distribution during RF ablation. The optimization with mono- or bipolar systems: A probe, connected to an electric generator, is placed inside the malignant tissue, such that an electric current flows through the body and heats the tissue near the probe up

Preusser, Tobias

191

Radio frequency analog electronics based on carbon nanotube transistors  

E-Print Network (OSTI)

, and Hong Zhang** Departments of *Physics, Materials Science and Engineering, §Electrical and Computer Engineering, and ¶Chemistry, Beckman Institute for Advanced Science and Technology, and Frederick Seitz, RF mixers, and audio amplifiers. These results represent important first steps to practical

Rogers, John A.

192

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

193

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

SciTech Connect

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

194

Observation of Radio-Frequency Confinement of a Plasma  

Science Journals Connector (OSTI)

The breakdown field in a microwave cavity excited in the electric quadrupole mode exhibits a plateau at pressures below the electron mean-free-path limit of diffusion-controlled breakdown. The luminosity of a steady-state plasma in this domain exhibits a maximum at the central nodal point in the cavity field. These results are interpreted as evidence of rf confinement of a low-density plasma.

Charles F. Shelby and Albert J. Hatch

1972-09-25T23:59:59.000Z

195

Charged-species profiles in electronegative radio-frequency plasmas  

Science Journals Connector (OSTI)

The negative ion density profile in a low pressure oxygen rf plasma has been measured by a photodetachment technique. At an rf power of 10 W and a neutral pressure of 10 mTorr, a parabolic negative ion density profile is obtained with a peak density of 8×1015 m-3 and a maximum ratio of negative ion to electron densities n-/ne?18. Under these conditions, the most abundant positive ion, determined by ion mass spectrometry, is O2+ with O+ being less than 10% of the positive ion density. The most abundant negative ion is O- with O2- and O3- being less than 20% of the total negative charge density. The maximum in the density profile of negative ions shifts closer to the powered rf electrode as the pressure is increased in the asymmetric system. Comparison of the results to theory indicates that the asymmetry follows from an enhancement of the ionization rate near the powered electrode sheath. The parabolic profile is also obtained in CCl2F2 at low pressure. Simulations and measurements show a rapid drop in ion density near the sheath that may be related to the recently discussed ‘‘stratification’’ phenomenon in electronegative plasmas.

D. Vender; W. W. Stoffels; E. Stoffels; G. M. W. Kroesen; F. J. de Hoog

1995-03-01T23:59:59.000Z

196

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

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

197

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

198

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

SciTech Connect

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

199

Determination of radio-frequency phase in harmonic frequency modulation spectroscopy  

Science Journals Connector (OSTI)

We have devised two useful schemes to determine the rf phase of the modulation waveforms in harmonic FM spectroscopy, a novel technique that we reported recently for the removal of...

Shum, Chi Man; Whittaker, Edward A

1991-01-01T23:59:59.000Z

200

CO2 laser frequency stabilization using the radio-frequency optogalvanic Lamb dip  

Science Journals Connector (OSTI)

The Lamb dip of the CO2 saturation signal in an extracavity low-pressure CO2–N2 rf glow discharge is detected optogalvanically and used to stabilize...

Tsai, Chin-Chun; Lin, Tyson; Shieh, Cherng-Yn; Yen, Tsu-Chiang; Shy, Jow-Tsong

1991-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" 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.


201

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

SciTech Connect

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

202

Negative ions in a radio-frequency oxygen plasma  

Science Journals Connector (OSTI)

A systematic study of a low pressure (5–200 mTorr) oxygen discharge is presented. Measurements of the electron and negative ion densities in the 13.56 MHz capacitively coupled plasma are performed by means of a microwave resonance technique in combination with photodetachment. A kinetic model is developed, incorporating volume and wall reactions of ions as well as neutral species. It is shown, by matching the experimental results with the model, that the dominant ion is O- whereas the O2- and O3- densities reach 10 to 20 % of the total negative ion density. The ratio of negative ion to electron density varies between 5 and 10 and decreases with pressure and rf power. The total negative ion density is about 5×1015 m-3, it increases with gas flow, is independent of the rf input power, and has a maximum at a pressure of 30 mTorr. The agreement between the measurements and the model is within the experimental error for a wide range of conditions. Deviations are explained by changes in the gas and wall temperatures. From the known ion density the effective ionization rate has been determined and related to the electron temperature. The ionization temperature obtained in this way varies between 2 and 4 eV and decreases with increasing gas pressure and power, as expected for the bulk electron temperature in this type of discharge.

E. Stoffels; W. W. Stoffels; D. Vender; M. Kando; G. M. W. Kroesen; F. J. de Hoog

1995-03-01T23:59:59.000Z

203

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

SciTech Connect

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

204

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

205

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

206

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

SciTech Connect

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

207

Atmospheric Pressure RF (13.56 MHz) Glow Discharge: Characterization and Application to “In Line” Waste Water Treatment  

Science Journals Connector (OSTI)

In this work the results obtained from the experimental study of an Atmospheric Pressure Glow Discharge (APGD) appear, generated in Helium (He) and dry air mixture by using a radio frequency (RF 13.56 MHz) pow...

Jaime B. Castro; Marlon H. Guerra-Mutis…

2003-06-01T23:59:59.000Z

208

A comparative study of CH4 and CF4 rf discharges using a consistent plasma physics and chemistry simulator  

Science Journals Connector (OSTI)

A self-consistent, one-dimensional simulator for the physics and chemistry of radio frequency (rf) plasmas was developed and applied for CH4 and CF4. The simulator consists of a fluid model for the discharge phys...

Nikolaos V. Mantzaris; Evangelos Gogolides…

1996-09-01T23:59:59.000Z

209

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

210

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.

211

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

SciTech Connect

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

212

Single shot time stamping of ultrabright radio frequency compressed electron pulses  

SciTech Connect

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

213

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.

214

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

215

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

216

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

217

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

218

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

219

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.

220

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

222

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

223

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

224

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

SciTech Connect

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

225

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

226

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

227

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

228

A computer program for HVDC converter station RF noise calculations  

SciTech Connect

HVDC converter station operations generate radio frequency (RF) electromagnetic (EM) noise which could interfere with adjacent communication and computer equipment, and carrier system operations. A generic Radio Frequency Computer Analysis Program (RAFCAP) for calculating the EM noise generated by valve ignition of a converter station has been developed as part of a larger project. The program calculates RF voltages, currents, complex power, ground level electric field strength and magnetic flux density in and around an HVDC converter station. The program requires the converter station network to be represented by frequency dependent impedance functions. Comparisons of calculated and measured values are given for an actual HVDC station to illustrate the validity of the program. RAFCAP is designed to be used by engineers for the purpose of calculating the RF noise produced by the igniting of HVDC converter valves.

Kasten, D.G.; Caldecott, R.; Sebo, S.A. (Ohio State Univ., Columbus, OH (United States). Dept. of Electrical Engineering); Liu, Y. (Virginia Polytechnic Inst. State Univ., Blacksburg, VA (United States). Bradley Dept. of Electrical Engineering)

1994-04-01T23:59:59.000Z

229

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

230

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

SciTech Connect

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

231

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

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

232

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

SciTech Connect

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

233

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

SciTech Connect

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

234

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

235

Communication methods, systems, apparatus, and devices involving RF tag registration  

DOE Patents (OSTI)

One technique of the present invention includes a number of Radio Frequency (RF) tags that each have a different identifier. Information is broadcast to the tags from an RF tag interrogator. This information corresponds to a maximum quantity of tag response time slots that are available. This maximum quantity may be less than the total number of tags. The tags each select one of the time slots as a function of the information and a random number provided by each respective tag. The different identifiers are transmitted to the interrogator from at least a subset of the RF tags.

Burghard, Brion J. (W. Richland, WA); Skorpik, James R. (Kennewick, WA)

2008-04-22T23:59:59.000Z

236

Onset of chaos and dc current-voltage characteristics of rf-driven Josephson junctions in the low-frequency regime  

Science Journals Connector (OSTI)

A comprehensive picture of the dc current-voltage (I-V) characteristics of rf-driven Josephson junctions in the low-frequency regime is presented. The boundary of the low-frequency regime is roughly defined by the junction characteristic frequency for overdamped junctions, and by the inverse of the junction damping time for underdamped junctions. An adiabatic model valid for the low-frequency regime is used to describe the overall shapes of the I-V curves, which is in good agreement with both the numerical simulations and the experimental results. For underdamped junctions, the Shapiro steps are the prominent features on the I-V curves if the rf frequency is sufficiently below the boundary. As the rf frequency is increased towards the boundary, large negatively-going tails on top of the Shapiro steps are observed both experimentally and numerically. Numerical simulations using the resistively- and capacitively-shunted-junction model (RCSJ model) reveal that the negatively-going tail is a signature of the low-frequency boundary of the junction chaotic regime. With use of the adiabatic model and the existence of plasma oscillations for underdamped junctions, the onset of chaos and its effect on the Shapiro steps can be fully explained. The high-frequency limit of the adiabatic model and the chaotic behavior of the Josephson junctions beyond the low-frequency regime are also briefly discussed.

C. C. Chi and C. Vanneste

1990-12-01T23:59:59.000Z

237

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

238

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

239

Safety assessment for the rf Test Facility  

SciTech Connect

The Radio Frequency Test Facility (RFTF) is a part of the Magnetic Fusion Program's rf Heating Experiments. The goal of the Magnetic Fusion Program (MFP) is to develop and demonstrate the practical application of fusion. RFTF is an experimental device which will provide an essential link in the research effort aiming at the realization of fusion power. This report was compiled as a summary of the analysis done to ensure the safe operation of RFTF.

Nagy, A.; Beane, F. (eds.)

1984-08-01T23:59:59.000Z

240

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

SciTech Connect

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

242

PIC–MCC Simulations of Capacitive High-Frequency Discharge Dynamics with Nanoparticles  

Science Journals Connector (OSTI)

A new combined particle-in-cell Monte Carlo collision (PIC–MCC) approach is discussed for accurate and fast simulation of a radio-frequency (rf) discharge at a low gas pressure and high plasma density. Test calcu...

Irina V. Schweigert

2010-01-01T23:59:59.000Z

243

High voltage RF feedthrough bushing  

DOE Patents (OSTI)

Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

Grotz, Glenn F. (Huntington Station, NY)

1984-01-01T23:59:59.000Z

244

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

SciTech Connect

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

245

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

SciTech Connect

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

246

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

247

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

248

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

249

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

SciTech Connect

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

250

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.

251

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

252

Operation of a planar-electrode ion trap array with adjustable RF electrodes  

E-Print Network (OSTI)

One path to scaling-up trapped atomic ions for large-scale quantum computing and simulation is to create a two-dimensional array of ion traps in close proximity to each other. A method to control the interactions between nearest neighboring ions is demonstrated and characterized here, using an adjustable radio-frequency (RF) electrode between trapping sites. A printed circuit board planar-electrode ion trap is demonstrated, trapping laser-cooled $^{40}$Ca$^+$ ions. RF shuttling and secular-frequency adjustment are shown as a function of the power applied to the addressed RF electrode. The trapped ion's heating rate is measured via a fluorescence recooling method.

Muir Kumph; Philip Holz; Kirsten Langer; Michael Niedermayr; Michael Brownnutt; Rainer Blatt

2014-02-04T23:59:59.000Z

253

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

254

RF-driven advanced modes of ITER operation  

SciTech Connect

The impact of the Radio Frequency heating and current drive systems on the ITER advanced scenarios is analyzed by means of the CRONOS suite of codes for integrated tokamak modelling. As a first step, the code is applied to analyze a high power advanced scenario discharge of JET in order to validate both the heating and current drive modules and the overall simulation procedure. Then, ITER advanced scenarios, based on Radio Frequency systems, are studied on the basis of previous results. These simulations show that both hybrid and steady-state scenarios could be possible within the ITER specifications, using RF heating and current drive only.

Garcia, J.; Artaud, J. F.; Basiuk, V.; Decker, J.; Giruzzi, G.; Hawkes, N.; Imbeaux, F.; Litaudon, X.; Mailloux, J.; Peysson, Y.; Schneider, M. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Brix, M. [UKAEA/Euratom Fusion Association, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom)

2009-11-26T23:59:59.000Z

255

Development of an RF Conditioning System for Charged-Particle Accelerators  

SciTech Connect

Charged-particle accelerators use various vacuum windows on their accelerating radio-frequency (RF) cavities to throughput very high RF power. Before being placed on the cavities, the windows should be cleaned, baked, and fully RF conditioned to prevent a poor vacuum from outgassing, as well as other forms of contamination. An example is the coaxial fundamental power coupler (FPC) with an annular alumina ceramic window for each of the 81 superconducting RF cavities in the Spallation Neutron Source (SNS) linear accelerator. The FPCs needed to be tested up to 650-kW peak in a traveling wave and 2.6 MW with standing wave peaks in 1.3 and 60 pulses/s at 805 MHz. In this paper, an Experimental-Physics-and-Industrial-Control-System-based RF conditioning system for the SNS RF test facility is presented. This paper summarizes the hardware and software design strategies, provides the results obtained, and describes the future research scope.

Kang, Yoon W [ORNL; Howlader, Mostofa [ORNL; Shajedul Hasan, Dr. S. M. [Virginia Polytechnic Institute and State University (Virginia Tech)

2008-01-01T23:59:59.000Z

256

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

SciTech Connect

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

257

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

SciTech Connect

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

258

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

259

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

SciTech Connect

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

260

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

Note: This page contains sample records for the topic "rf radio frequency" from the National Library of EnergyBeta (NLEBeta).
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261

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

SciTech Connect

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

262

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

263

Laser polishing of niobium for application to superconducting radio frequency cavities  

SciTech Connect

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

264

Phase-Resolved Measurements of Ion Velocity in a Radio-Frequency Sheath  

SciTech Connect

The time-dependent argon-ion velocity distribution function above and within the plasma sheath of an rf-biased substrate has been measured using laser-induced fluorescence in a commercial plasma processing tool. Discharge parameters were such that the 2.2 MHz rf-bias period was on the order of the ion transit time through the sheath ({tau}{sub ion}/{tau}{sub rf}=0.3). This work embodies the first time-resolved measurement of ion velocity distribution functions within an rf-biased sheath over a large area (30 cm diameter) silicon wafer substrate.

Jacobs, Brett; Gekelman, Walter; Pribyl, Pat [Department of Physics and Astronomy, University of California--Los Angeles, Los Angeles, California 90024 (United States); Barnes, Michael [MS Barnes Engineering, San Ramon, California 94583 (United States)

2010-08-13T23:59:59.000Z

265

Development of the RF plasma source at atmospheric pressure  

Science Journals Connector (OSTI)

A radio frequency (RF) plasma source operates by feeding helium or argon gas through two coaxial electrodes driven by a 13.56 \\{MHz\\} RF source. In order to prevent an arc discharge, a dielectric material is loaded outside the center electrode. A stable, arc-free discharge is produced at a flow rate of 1.5 l/min of helium gas. The temperature of the gas flame varies from 100 to 150 °C depending on the RF power. The breakdown voltage also changes when the flow rate varies. The plasma generation in a hot chamber is much more efficient than that in a cold chamber. The plasma characteristics are diagnosed by using optical emission spectroscopy. One of the applications of the RF plasma source is the printed circuit board (PCB) cleaning process, needed for environmental protection. The PCB cleaning device forms an asymmetric biaxial reactor.

Jung G. Kang; Hyoung S. Kim; Sung W. Ahn; Han S. Uhm

2003-01-01T23:59:59.000Z

266

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

267

System efficiency analysis for high power solid state radio frequency transmitter  

SciTech Connect

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

268

Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF4/O2 plasmas using  

E-Print Network (OSTI)

emission spectroscopy TRG-OES . The parallel plate etcher was powered by a high frequency 60 MHz "source frequency LF source, while the plasma density and ion flux are determined mainly by the high frequency HF-dimensional model of a 2f-CCP driven by the superposition of two sinusoidal radio-frequency rf voltages. They found

Economou, Demetre J.

269

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

270

Characteristics of Hydrogen Negative Ion Source with FET based RF System  

SciTech Connect

Characteristics of radio frequency (RF) plasma production were investigated using a FET inverter power supply as a RF generator. High density hydrogen plasma was obtained using an external coil wound a cylindrical ceramic tube (driver region) with RF frequency of lower than 0.5 MHz. When an axial magnetic field around 10 mT was applied to the driver region, an electron density increased drastically and attained to over 10{sup 19} m{sup -3} in the driver region. Effect of the axial magnetic field in driver and expansion region was examined. Lower gas pressure operation below 0.5 Pa was possible with higher RF frequency. H{sup -} density in the expansion region was measured by using laser photo-detachment system. It decreased as the axial magnetic field applied, which was caused by the increase of energetic electron from the driver.

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

2011-09-26T23:59:59.000Z

271

Radio-frequency powered glow discharge device and method with high voltage interface  

DOE Patents (OSTI)

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components. 11 figures.

Duckworth, D.C.; Marcus, R.K.; Donohue, D.L.; Lewis, T.A.

1994-06-28T23:59:59.000Z

272

Coherent Anti-Stokes Raman Spectroscopy of Radio-Frequency Discharge Plasmas of Silane and Disilane  

Science Journals Connector (OSTI)

Coherent anti-Stokes Raman spectroscopy has been employed for the diagnosis of rf discharges of silane (SiH4) and disilane (Si2H6). The signal intensities from silane and disilane have been measured as a function of time after switching-on the rf power supplied to SiH4 and Si2H6 gas in a closed reaction chamber. From this measurement, the loss rates of silane and disilane have been determined directly as functions of the rf-power density and gas pressure for the first time. The rate of formation of SiH4 in disilane discharge plasmas has also been determined.

Nobuhiro Hata; Akihisa Matsuda; Kazunobu Tanaka

1986-01-01T23:59:59.000Z

273

Stable transmission of radio frequency signals on fiber links using interferomectric delay sensing  

SciTech Connect

The authors demonstrate distribution of a 2850 MHz rf signal over stabilized optical fiber links. For a 2.2 km link they measure an rms drift of 19.4 fs over 60 h, and for a 200 m link an rms drift of 8.4 fs over 20 h. The rf signals are transmitted as amplitude modulation on a continuous optical carrier. Variations in the delay length are sensed using heterodyne interferometry and used to correct the rf phase. The system uses standard fiber telecommunications components.

Wilcox, Russell B.; Byrd, J.M.; Doolittle, Lawrence; Huang, Gang; Staples, J.W.

2009-07-29T23:59:59.000Z

274

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

SciTech Connect

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

275

Radio-frequency Stark tuning of optically pumped far-infrared lasers  

Science Journals Connector (OSTI)

We have directly monitored the rf Stark-field-induced splitting of the gain profile of the 1222-?m 13CH3F optically pumped far-infrared (OPFIR) laser transition....

Skatrud, David D; De Lucia, Frank C

1985-01-01T23:59:59.000Z

276

Three dimensional complex plasma structures in a combined radio frequency and direct current discharge  

SciTech Connect

We report on the first detailed analysis of large three dimensional (3D) complex plasma structures in experiments performed in pure rf and combined rf+dc discharge modes. Inductively coupled plasma is generated by an rf coil wrapped around the vertically positioned cylindrical glass tube at a pressure of 0.3 mbar. In addition, dc plasma can be generated by applying voltage to the electrodes at the ends of the tube far from the rf coil. The injected monodisperse particles are levitated in the plasma below the coil. A scanning laser sheet and a high resolution camera are used to determine the 3D positions of about 10{sup 5} particles. The observed bowl-shaped particle clouds reveal coexistence of various structures, including well-distinguished solid-like, less ordered liquid-like, and pronounced string-like phases. New criteria to identify string-like structures are proposed.

Mitic, S.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany); Klumov, B. A. [Joint Institute for High Temperatures, Moscow 125412 (Russian Federation); Khrapak, S. A. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany); Joint Institute for High Temperatures, Moscow 125412 (Russian Federation)

2013-04-15T23:59:59.000Z

277

Ways to improve the efficiency and reliability of radio frequency driven negative ion sources for fusion  

SciTech Connect

Large RF driven negative hydrogen ion sources are being developed at IPP Garching for the future neutral beam injection system of ITER. The overall power efficiency of these sources is low, because for the RF power supply self-excited generators are utilized and the plasma is generated in small cylindrical sources (“drivers”) and expands into the source main volume. At IPP experiments to reduce the primary power and the RF power required for the plasma production are performed in two ways: The oscillator generator of the prototype source has been replaced by a transistorized RF transmitter and two alternative driver concepts, a spiral coil, in which the field is concentrated by ferrites, which omits the losses by plasma expansion and a helicon source are being tested.

Kraus, W., E-mail: kraus@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik (IPP), Boltzmannstr. 2, 85748 Garching (Germany); Briefi, S.; Fantz, U. [Max-Planck-Institut für Plasmaphysik (IPP), Boltzmannstr. 2, 85748 Garching (Germany) [Max-Planck-Institut für Plasmaphysik (IPP), Boltzmannstr. 2, 85748 Garching (Germany); AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg (Germany); Gutmann, P.; Doerfler, J. [AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg (Germany)] [AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg (Germany)

2014-02-15T23:59:59.000Z

278

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

SciTech Connect

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

279

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

SciTech Connect

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

280

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

SciTech Connect

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

SciTech Connect

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

282

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

SciTech Connect

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

283

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

SciTech Connect

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

284

Studies of RF Noise Induced Bunch Lengthening at the LHC  

SciTech Connect

Radio Frequency (RF) noise induced bunch lengthening can strongly affect the Large Hadron Collider (LHC) performance through luminosity reduction, particle loss, and other effects. This work presents measurements from the LHC that better quantify the relationship between the RF noise and longitudinal emittance blowup and identify the performance limiting RF components. The experiments presented in this paper confirmed the predicted effects on the LHC bunch length growth. Dedicated measurements were conducted in the LHC to gain insight in the effect of RF noise to the longitudinal beam diffusion. It was evident that the growth rate of the bunch length is strongly related to the accelerating voltage phase noise power spectral density around f{sub s} + kf{sub rev}, as predicted in [4]. The noise threshold for 2.5 ps/hr growth was estimated to -101 dBc/Hz (SSB flat noise spectral density from f{sub s} to the edge of the closed loop bandwidth). A 9 dB margin is achieved with the current RF configuration and the BPL on. With this formalism it is now possible to estimate the effect of different operational and technical RF configurations on the LHC beam diffusion. This formalism could also be useful for the design of future RF systems and the budgeting of the allowed noise.

Mastorides, T.; Rivetta, C.; Fox, J.D.; Baudrenghien, P.; Butterworth, A.; Molendijk, J.; /SLAC /CERN

2011-08-17T23:59:59.000Z

285

Synthesis of a material for semiconductor applications: Boron oxynitride prepared by low frequency rf plasma-assisted metalorganic chemical  

E-Print Network (OSTI)

rf plasma-assisted metalorganic chemical vapor deposition G. C. Chen, D.-C. Lim, S.-B. Lee, and J-derived plasma-assisted metalorganic chemical vapor deposition MOCVD , and have studied the electrical compounds have become promising functional materials for integrated circuits, flash memories, and solar

Boo, Jin-Hyo

286

Nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging  

DOE Patents (OSTI)

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Fukushima, Eiichi (Los Alamos, NM); Roeder, Stephen B. W. (La Mesa, CA); Assink, Roger A. (Albuquerque, NM); Gibson, Atholl A. V. (Bryan, TX)

1986-01-01T23:59:59.000Z

287

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

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

288

The influence of external parameters on the peculiarities of a hybrid low-pressure radio-frequency discharge  

Science Journals Connector (OSTI)

This paper deals with the experimental study of the patterns of the RF power input into the plasma of a hybrid RF discharge that was sustained by an RF power unit, which consisted of a spiral ... with capacitor e...

K. V. Vavilin; M. A. Gomorev; E. A. Kralkina…

2012-02-01T23:59:59.000Z

289

RF Cavity Characterization with VORPAL  

SciTech Connect

When designing a radio frequency (RF) accelerating cavity structure various figures of merit are considered before coming to a final cavity design. These figures of merit include specific field and geometry based quantities such as the ratio of the shunt impedance to the quality factor (R/Q) or the normalized peak fields in the cavity. Other important measures of cavity performance include the peak surface fields as well as possible multipacting resonances in the cavity. High fidelity simulations of these structures can provide a good estimate of these important quantities before any cavity prototypes are built. We will present VORPAL simulations of a simple pillbox structure where these quantities can be calculated analytically and compare them to the results from the VORPAL simulations. We will then use VORPAL to calculate these figures of merit and potential multipacting resonances for two cavity designs under development at Jefferson National Lab for Project X.

C. Nieter, C. Roark, P. Stoltz, C.D. Zhou, F. Marhauser

2011-03-01T23:59:59.000Z

290

Titanium nitride thin films deposited by reactive pulsed-laser ablation in RF plasma  

Science Journals Connector (OSTI)

Titanium nitride thin films were deposited on Si (100) substrates by pulsed laser ablation of a titanium target in a N2 atmosphere (gas pressure approx. 10 Pa) using a doubled frequency Nd:YAG laser (532 nm) also assisted by a 13.56-MHz radio frequency (RF) plasma. Deposition was carried out at various substrate temperatures ranging from 373 up to 873 K and films were analyzed by X-ray diffractometry, scanning electron microscopy and optical emission spectroscopy. A comparison between the ‘normal’ pulsed laser deposition (PLD) and the RF plasma-assisted PLD showed the influence of the plasma on the structural characteristics of the thin films.

A. Giardini; V. Marotta; S. Orlando; G.P. Parisi

2002-01-01T23:59:59.000Z

291

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

SciTech Connect

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

292

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

293

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

294

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

295

Diagnostic technique for measuring plasma parameters near surfaces in radio frequency discharges  

E-Print Network (OSTI)

of an inductively coupled plasma reactor which has an rf biased substrate. Although any three disjoint sets of measurements can ideally be used, a sensitivity analysis is used to show that certain sets may be more suitable reliability and performance. One ideally wants sensors that are nonobtrusive, simple to implement and which

Kushner, Mark

296

Towards a 3D time dependent Fokker-Planck solver for modelling RF heating in realistic tokamak geometry  

E-Print Network (OSTI)

. Hedin, Ion Cyclotron Heating in Toroidal Plasmas, Ph.D. thesis, Royal Institute of Technology StockholmTowards a 3D time dependent Fokker-Planck solver for modelling RF heating in realistic tokamak supercomputers and the need for predictive tools to guide the experiments, modelling radio frequency heating

297

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

SciTech Connect

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

298

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

SciTech Connect

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

299

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

300

Fluid modeling of radio frequency and direct currents in a biased magnetized plasma  

SciTech Connect

This model aims at simulating a magnetized plasma column connected on one side to a probe and on the other side to an ICRH (Ion Cyclotron Resonant Heating) antenna. This is a double probe modeling of a plasma flux tube exchanging perpendicular currents: rf polarization current and dc currents (inertia, viscous, and friction) perpendicular to the magnetic field. A self consistent solution for the rectified potential and the density is obtained under the assumptions of flute hypothesis, inertialess electrons, and no collision in parallel direction. The main effect of rf biasing on the antenna side is to shift the IV characteristic so that the floating potential can be increased up to ln(I{sub 0}(eV{sub rf}/(k{sub B}T{sub e}))), with I{sub 0} the modified Bessel function of the first kind. On the contrary, the effect of dc currents is to decrease the plasma potential and the sheath potential which can be lower than 3k{sub B}T{sub e}/e or even be negative. Experimental characteristics are well matched by the 1D fluid code and exhibit very high negative currents (more than 30 j{sub i} the ion saturation current) for high positive biasing of the probe and for long flux tube (10 m). The non-saturation of the electron current is here due to high transverse transport enhanced by convective fluxes and dc currents able to bring an amount of density around the biased flux tube. During comparisons with experiments, the floating potential measured by a reciprocating probe is recovered by the code revealing that for a 120 V measured peak potential on the probe, the rf potential on the ICRH antenna is twice this value. Finally, the density profile can be flattened or steepened as a function of the transverse dc current direction.

Faudot, E.; Heuraux, S. [IJL-P2M UMR 7198 CNRS, F-54506 Vandoeuvre les Nancy, IJL, P2M-Faculte des Sciences, Vandoeuvre les Nancy 54506 (France); Kubic, M.; Gunn, J.; Colas, L. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

2013-04-15T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" 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

The development of the radio frequency driven negative ion source for neutral beam injectors (invited)  

SciTech Connect

Large and powerful negative hydrogen ion sources are required for the neutral beam injection (NBI) systems of future fusion devices. Simplicity and maintenance-free operation favors RF sources, which are developed intensively at the Max-Planck-Institut fuer Plasmaphysik (IPP) since many years. The negative hydrogen ions are generated by caesium-enhanced surface conversion of atoms and positive ions on the plasma grid surface. With a small scale prototype the required high ion current density and the low fraction of co-extracted electrons at low pressure as well as stable pulses up to 1 h could be demonstrated. The modular design allows extension to large source dimensions. This has led to the decision to choose RF sources for the NBI of the international fusion reactor, ITER. As an intermediate step towards the full size ITER source at IPP, the development will be continued with a half-size source on the new ELISE testbed. This will enable to gain experience for the first time with negative hydrogen ion beams from RF sources of these dimensions.

Kraus, W.; Fantz, U.; Franzen, P.; Froeschle, M.; Heinemann, B.; Riedl, R.; Wuenderlich, D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)

2012-02-15T23:59:59.000Z

302

Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging  

DOE Patents (OSTI)

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Fukushima, E.; Roeder, S.B.W.; Assink, R.A.; Gibson, A.A.V.

1984-01-01T23:59:59.000Z

303

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

304

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

305

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

306

High frequency capacitively coupled RF plasma discharge effects on the order/disorder structure of PAN-based carbon fiber  

Science Journals Connector (OSTI)

High-resolution confocal Raman microscopy was used to investigate the effects of nitrogen plasma on unsized high strength (HS) PAN- ... . The fibers were treated by a high frequency (40.68 MHz) capacitively coupl...

Ümmugül E. Güngör; Sinan Bilikmen…

2014-05-01T23:59:59.000Z

307

Parameters of a collisional radio-frequency sheath and dust characteristics resulting from the microparticle levitation  

SciTech Connect

The screening length, the time-average electric field, and the particle charge as well as the local vertical gradients of these quantities are determined experimentally within a sheath of a capacitively coupled rf, 13.56 MHz, discharge at enhanced argon gas pressures of 30, 55, and 100 Pa. The parameters are derived directly from comparative measurements of levitation positions of the particles of different sizes and variations in the levitation heights caused by formation of new dust layers. The electrostatic effect of the horizontally extended dust layers on the sheath electric field is investigated.

Yaroshenko, V. V.; Antonova, T.; Thomas, H. M.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany)

2009-10-15T23:59:59.000Z

308

Experimental evaluation of 350 MHz RF accelerator windows for the low energy demonstration accelerator  

SciTech Connect

Radio frequency (RF) windows are historically a point where failure occurs in input power couplers for accelerators. To obtain a reliable, high-power, 350 MHz RF window for the Low Energy Demonstration Accelerator (LEDA) project of the Accelerator Production of Tritium program, RF windows prototypes from different vendors were tested. Experiments were performed to evaluate the RF windows by the vendors to select a window for the LEDA project. The Communications and Power, Inc. (CPI) windows were conditioned to 445 kW in roughly 15 hours. At 445 kW a window failed, and the cause of the failure will be presented. The English Electronic Valve, Inc. (EEV) windows were conditioned to 944 kW in 26 hours and then tested at 944 kW for 4 hours with no indication of problems.

Cummings, K.; Rees, D.; Roybal, W. [and others

1997-09-01T23:59:59.000Z

309

PRODUCTION OF LARGE VOLUME CYLINDRICAL RF PLASMA USING CIRCULAR MAGNETIC LINE CUSP FIELD  

Science Journals Connector (OSTI)

A large volume cylindrical rf (radio frequency) plasma source using a circular magnetic line cusp field has been developed for various large scale plasma processings. In this type of plasma source, a capacitively coupled 13.56 \\{MHz\\} rf plasma is produced in a circular magnetic line cusp field. Two versions of the plasma source have been constructed and tasted. The first version has a pair of peripheral rf electrodes placed outside the ionization chamber and is suitable for preparing a large volume uniform plasma. This plasma source can attain uniformity within 107 cm?3 over a 30 cm diameter region. The other which is provided with parallel doughnut plate electrodes forming part of the chamber wall serves as a high current plasma source, where the electron density is proportional to the rf power and equal to 7 × 109 cm?3 for 500 W.

K. YAMAUCHI; M. SHIBAGAKI; A. KONO; K. TAKAHASHI; T. SHEBUYA; E. YABE; K. TAKAYAMA

1993-01-01T23:59:59.000Z

310

High-voltage nanosecond pulses in a low-pressure radio-frequency discharge  

Science Journals Connector (OSTI)

An influence of a high-voltage (3–17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1–10 Pa) capacitively coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic regimes: a bright flash, occurring within 100 ns after the pulse (when the discharge emission increases by 2–3 orders of magnitude over the steady-state level), and a dark phase, lasting a few hundreds ?s (when the intensity of the discharge emission drops significantly below the steady-state level). The electron density increases during the flash and remains very large at the dark phase. 1D3V particle-in-cell simulations qualitatively reproduce both regimes and allow for detailed analysis of the underlying mechanisms. It is found that the high-voltage nanosecond pulse is capable of removing a significant fraction of plasma electrons out of the discharge gap, and that the flash is the result of the excitation of gas atoms, triggered by residual electrons accelerated in the electric field of immobile bulk ions. The secondary emission from the electrodes due to vacuum UV radiation plays an important role at this stage. High-density plasma generated during the flash provides efficient screening of the RF field (which sustains the steady-state plasma). This leads to the electron cooling and, hence, onset of the dark phase.

M. Y. Pustylnik; L. Hou; A. V. Ivlev; L. M. Vasilyak; L. Couëdel; H. M. Thomas; G. E. Morfill; V. E. Fortov

2013-06-10T23:59:59.000Z

311

Design And Diagnosis Of A New Type Radio Frequency Driven In Vacuum Arc Ion Source  

SciTech Connect

The discharge mechanism of this source is based on the use of both RF- driven (15 MHz -300W) and vacuum arc to create discharge plasma of higher intensity. An internal antenna is used to couple the RF power to the plasma. Lower ignition voltage (50 up to 200V) and higher plasma intensity feature the characteristics of this source. The source is considered self extracted ion current and could deliver ion currents of {approx}10mA for thin beam ({phi} = 2mm.) and {approx}20 mA for broad beam ({phi} {approx} 6cm.) at {approx} 200V extraction voltage. The beam diagnostics (for thin beam) of this source are measured which include: the beam profiles, beam emittance, energy spread and distribution of the ion species in the ion beam. The increase of the anode voltage decreases the beam emittance, while the energy spread increases with the decrease of the discharge pressure. The beam emittance is found to be around 200 up to 400 mm.m.rad. and the energy spread of the ions in the ion beam is around 40 up to 80 eV. The Ar ion specie extracted from the source could reach Ar+5. The beam profiles show that the beam is more convergent with the increase of the accelerating voltage and with the use of proper capacitors between the extraction electrodes.

Zakhary, S.G. [Accelerators Dept., Nuclear Research Center, Atomic Energy Authority, P.O.Box 13759 Cairo (Egypt)

2005-03-17T23:59:59.000Z

312

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

SciTech Connect

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

313

RF generation in the DARHT Axis-II beam dump  

SciTech Connect

We have occasionally observed radio-frequency (RF) electromagnetic signals in the downstream transport (DST) of the second axis linear induction accelerator (LIA) at the dual-axis radiographic hydrodynamic testing (DARHT) facility. We have identified and eliminated some of the sources by eliminating the offending cavities. However, we still observe strong RF in the range 1 GHz t0 2 GHz occurring late in the {approx}2-{micro}s pulse that can be excited or prevented by varying the downstream tune. The narrow frequency width (<0.5%) and near exponential growth at the dominant frequency is indicative of a beam-cavity interaction, and electro-magnetic simulations of cavity structure show a spectrum rich in resonances in the observed frequency range. However, the source of beam produced RF in the cavity resonance frequency range has not been identified, and it has been the subject of much speculation, ranging from beam-plasma or beam-ion instabilities to unstable cavity coupling.

Ekdahl, Carl A. Jr. [Los Alamos National Laboratory

2012-05-03T23:59:59.000Z

314

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

315

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.

316

Observation of ? mode electron heating in dusty argon radio frequency discharges  

SciTech Connect

The time-resolved emission of argon atoms in a dusty plasma has been measured with phase-resolved optical emission spectroscopy using an intensified charge-coupled device camera. For that purpose, three-dimensional dust clouds have been confined in a capacitively coupled rf argon discharge with the help of thermophoretic levitation. While electrons are exclusively heated by the expanding sheath (? mode) in the dust-free case, electron heating takes place in the entire plasma bulk when the discharge volume is filled with dust particles. Such a behavior is known as ? mode, first observed in electronegative plasmas. Furthermore, particle-in-cell simulations have been carried out, which reproduce the trends of the experimental findings. These simulations support previous numerical models showing that the enhanced atomic emission in the plasma can be attributed to a bulk electric field, which is mainly caused by the reduced electrical conductivity due to electron depletion.

Killer, Carsten; Bandelow, Gunnar; Schneider, Ralf; Melzer, André [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany); Matyash, Konstantin [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)] [Universitätsrechenzentrum, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)

2013-08-15T23:59:59.000Z

317

About the conditions of suppression of turbulence effects on the poloidal fluxes in thoroidal plasmas in the presence of RF heating  

E-Print Network (OSTI)

plasmas in the presence of RF heating N. Pometescu University of Craiova, Association EURATOM of the poloidal particle and heat fluxes in the thoroidal plasmas due to electrostatic turbulence in the presence of external Radio Frequency heating. The effects of the electrostatic turbulence contain two terms. One

318

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

319

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

SciTech Connect

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

320

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

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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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321

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

SciTech Connect

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

322

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

SciTech Connect

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

323

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

324

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

325

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

326

High-voltage R-F feedthrough bushing  

DOE Patents (OSTI)

Described is a multi-element, high voltage radio frequency bushing for transmitting rf energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

Grotz, G.F.

1982-09-03T23:59:59.000Z

327

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.

328

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

329

Design of a horizontal test cryostat for superconducting RF cavities for the FREIA facility at Uppsala University  

SciTech Connect

Uppsala University is constructing a large scale facility, called FREIA (Facility for Research Instrumentation and Accelerator Development). FREIA includes a helium liquefier and an accelerator test facility and has the capacity to test superconducting radio-frequency (RF) cavities with the same RF system and RF power level as in an accelerator. A central element of FREIA is a horizontal test cryostat connected in closed loop to a helium liquefier. This cryostat can house two fully equipped (tuners, piezo, power coupler, helium tank) superconducting cavities to perform full RF high power tests and operate at temperatures between 1.8 K and 4.2 K. The cryostat is designed to accommodate a large array of superconducting cavities and magnets, among which the European Spallation Source (ESS) type spoke and high-? elliptical cavities as well as TESLA/ILC type elliptical cavities. The present status of the project and the design of the cryostat are reported.

Chevalier, N. R.; Thermeau, J.-P.; Bujard, P.; Junquera, T. [Accelerators and Cryogenic Systems (ACS), 86 rue de Paris, 91400 Orsay (France); Hermansson, L.; Kern, R. Santiago; Ruber, R. [Uppsala University, Department of Physics and Astronomy, 75120 Uppsala (Sweden)

2014-01-29T23:59:59.000Z

330

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

331

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

332

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

333

Final Technical Report- Back-gate Field Emission-based Cathode RF Electron Gun  

SciTech Connect

The objective was to complete the design of an electron gun which utilizes a radio frequency (RF) power source to apply a voltage to a field emission (FE) cathode, a so called cold cathode, in order to produce an electron beam. The concept of the RF electron gun was originally conceived at Argonne National Laboratory but never reduced to practice. The research allowed the completion of the design based upon the integration of the FE electron source. Compared to other electron guns, the RF gun is very compact, less than one third the size of other comparable guns, and produces a high energy (to several MeV), high quality, high power electron beam with a long focal length with high repetition rates. The resultant electron gun may be used in welding, materials processing, analytical equipment and waste treatment.

McGuire, Gary; Martin, Allen; Noonan, John

2010-10-30T23:59:59.000Z

334

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

335

Special Presentation: Key Findings from the Barrier Immune Radio  

NLE Websites -- All DOE Office Websites (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

336

On the scaling of rf and dc self-bias voltages with pressure in electronegative capacitively coupled plasmas  

SciTech Connect

Higher gas densities and lower diffusion losses at higher operating pressures typically lead to increased charged species densities (and hence flux) for a constant power deposition in capacitively coupled plasmas (CCP). As a result, one would expect that the bias radio-frequency (rf) voltage required to deposit a given power in a CCP reactor decreases with increasing operating pressure. These observations may not hold true in multiple frequency CCPs, commonly used for dielectric etching in microelectronics fabrication, due to nonlinear interactions between the rf sources. Wafer-based measurements of the rf and self-generated direct current (dc) bias voltages in a dual-frequency capacitively coupled electronegative plasma were made, which indicate that the rf and dc voltages vary nonmonotonically with pressure. These experimental results are presented in this paper and a computational plasma model is used to explain the experimental observations for varying 60 MHz and 13 MHz powers in the Ar/CF{sub 4}/CHF{sub 3} plasma over a pressure range of 25 to 400 mTorr. The authors found that while the ion density increases with pressure, the increase is most dominant near the electrode with the high frequency source (60 MHz). The rf and dc bias voltages are ultimately influenced by both charged species density magnitudes and spatial profiles.

Agarwal, Ankur; Dorf, Leonid; Rauf, Shahid; Collins, Ken [Applied Materials Inc., 974 E. Arques Avenue, M/S 81312, Sunnyvale, California 94085 (United States)

2012-03-15T23:59:59.000Z

337

The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array  

SciTech Connect

Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as 'plasma bullet' is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P. [National State Key Lab of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, Hubei 430074 (China); Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

2012-06-15T23:59:59.000Z

338

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

339

Polymer film deposition in inductively coupled radio-frequency discharge plasma of perfluorocyclobutane mixed with sulfur hexafluoride  

Science Journals Connector (OSTI)

The effect of an SF6...admixture on the rate of formation and the composition of a polymer film deposited on a substrate in low-pressure inductively coupled radiofrequency (RF) discharge plasma of C4F8 + SF6 unde...

I. I. Amirov; N. V. Alov

340

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

Note: This page contains sample records for the topic "rf radio frequency" 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

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

SciTech Connect

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

342

Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures  

E-Print Network (OSTI)

. There is a considerable body of research investigating rare gas- halogen kinetics in the context of atmospheric pressure. The plasma is sustained in an 3.8 cm i.d. by 7.6-cm- long quartz tube. The excitation coil is a solenoid, and having eight and three-quarters turns. Variable rf power is supplied to the sys- tem at 11.3 MHz. Iodine

Kushner, Mark

343

Experimental Investigation of RF Sheath Rectification in ICRF and LH Heated Plasmas on Alcator C-Mod  

SciTech Connect

Radio frequency (RF) rectification of the plasma sheath is being actively studied on C-Mod as a likely mechanism that leads to prohibitively high molybdenum levels in the plasma core of ion cyclotron RF (ICRF) heated discharges. We installed emissive, ion sensitive, Langmuir, and 3-D B-dot probes to quantify the plasma potentials ({Phi}{sub P}) in ICRF and lower hybrid (LH) heated discharges. Two probe sets were mounted on fixed limiter surfaces and one set of probes was mounted on a reciprocating (along the major radius) probe. Initial results showed that RF rectification is strongly dependent on the local plasma density and not on the local RF fields. The RF sheaths had a threshold-like appearance at the local density of {approx}10{sup 16} m-{sup 3}. Radial probe scans revealed that the RF sheaths peaked in the vicinity of the ICRF limiter surface, agreeing with a recent theory. The highest {Phi}{sub P}'s were observed on magnetic field lines directly mapped to the active ICRF antenna. Measurements in LH heated plasmas showed a strong {Phi}{sub P} dependence on the parallel index of refraction n{sub ||} of the launched LH waves: {Phi}{sub P} is greater at lower n{sub ||}. Little dependence was observed on the local plasma density.

Ochoukov, R.; Whyte, D. G.; Faust, I.; LaBombard, B.; Lipschultz, B.; Meneghini, O.; Wallace, G.; Wukitch, S. [MIT Plasma Science and Fusion Center, Cambridge (United States); Myra, J. [Lodestar Research Corporation, Boulder, Colorado (United States)

2011-12-23T23:59:59.000Z

344

Development of a bellows chamber with a comb-type RF shield for high-current accelerators  

Science Journals Connector (OSTI)

An all-metal bellows chamber with a comb-type Radio Frequency (RF) shield for a high-current accelerator was developed and tested at the KEK B-factory (KEKB). The comb-type RF shield has no thin fingers but has nested comb teeth instead at an inner surface. The comb-type RF-shield has a higher thermal strength structurally compared to the conventional finger-type one. Leakage of the TE mode like HOM through the RF shield is almost suppressed. Two test models of bellows chambers installed in the 3.5 GeV positron ring of KEKB showed good properties up to a stored beam current of 1.5 A. The temperature rise of the corrugation was about 7°C and the temperature rise was about 16 of that of the bellows chamber with a conventional finger-type RF shield located under the same condition. The temperature rise of the comb teeth was about 22°C, while that of fingers of the finger-type RF shield was estimated to be about 105°C for the equivalent HOM power. No vacuum arcing was detected during beam operation.

Y. Suetsugu; M. Shirai; K. Shibata; K. Murata; M. Kaneko; K. Sakamoto; K. Sugisaki; M. Kawahara

2004-01-01T23:59:59.000Z

345

Self-consistent electrodynamics of large-area high-frequency capacitive plasma discharge  

SciTech Connect

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

346

Robotic localization of hostile networked radio sources with a directional antenna  

E-Print Network (OSTI)

networks. Imagine a scenario, there is a sensor network deployed by enemy. We dispatch a mobile robot equipped with directional Radio Frequency (RF) antenna to search and destroy the networked radio sources. We need an effective scheme to guide the robot... to take the best guess for each step given the current information and known knowledge. Mathemat- ically, Bayes rule is often used to compute the posterior possibility p(X|d) according to the prior possibility p(X). p(X|d) = etap(d|X)p(X). (3.1) Suppose we...

Hu, Qiang

2007-04-25T23:59:59.000Z

347

Development of an rf driven multicusp ion source for nuclear science experiments  

Science Journals Connector (OSTI)

A compact 13.56 \\{MHz\\} radio-frequency (rf) driven multicusp ion source is under development at Lawrence Berkeley National Laboratory (LBNL) for radioactive ion beam applications. In this paper we describe the ion source design and the general ion source performance using H2, Ar, Xe gas and a 90% Ar/10% CO gas mixture for generating the discharge plasma. The following ion source characteristics have been analyzed: extractable ion current, ion species distributions, ionization efficiency for nobel gases, axial energy spread and ion beam emittance measurements. This ion source can generate ion current densities of approximately 60 mA/cm2.

D Wutte; S Freedman; R Gough; Y Lee; M Leitner; K.N Leung; C Lyneis; D.S Pickard; M.D Williams; Z.Q Xie

1998-01-01T23:59:59.000Z

348

Plasma processing of large curved surfaces for superconducting rf cavity modification  

SciTech Connect

Plasma based surface modification of niobium is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The development of the technology based on Cl2/Ar plasma etching has to address several crucial parameters which influence the etching rate and surface roughness, and eventually, determine cavity performance. This includes dependence of the process on the frequency of the RF generator, gas pressure, power level, the driven (inner) electrode configuration, and the chlorine concentration in the gas mixture during plasma processing. To demonstrate surface layer removal in the asymmetric non-planar geometry, we are using a simple cylindrical cavity with 8 ports symmetrically distributed over the cylinder. The ports are used for diagnosing the plasma parameters and as holders for the samples to be etched. The etching rate is highly correlated with the shape of the inner electrode, radio-frequency (RF) circuit elements, chlorine concentration in the Cl2/Ar gas mixtures, residence time of reactive species and temperature of the cavity. Using cylindrical electrodes with variable radius, large-surface ring-shaped samples and d.c. bias implementation in the external circuit we have demonstrated substantial average etching rates and outlined the possibility to optimize plasma properties with respect to maximum surface processing effect.

Upadhyay, J.; Im, Do; Popovi??, S.; Valente-Feliciano, A.-M.; Phillips, L.; Vuskovic, L

2014-12-01T23:59:59.000Z

349

RASDR: Benchtop Demonstration of SDR for Radio Astronomy  

SciTech Connect

The Society of Amateur Radio Astronomers (SARA) members present the benchtop version of RASDR, a Software Defined Radio (SDR) that is optimized for Radio Astronomy. RASDR has the potential to be a common digital receiver interface useful to many SARA members. This document describes the RASDR 0.0 , which provides digitized radio data to a backend computer through a USB 2.0 interface. A primary component of RASDR is the Lime Microsystems Femtocell chip which tunes from a 0.4-4 GHz center frequency with several selectable bandwidths from 0.75 MHz to 14 MHz. A second component is a board with a Complex Programmable Logic Device (CPLD) chip that connects to the Femtocell and provides two USB connections to the backend computer. A third component is an analog balanced mixer up conversion section. Together these three components enable RASDR to tune from 0.015 MHz thru 3.8GHz of the radio frequency (RF) spectrum. We will demonstrate and discuss capabilities of the breadboard system and SARA members will be able to operate the unit hands-on throughout the workshop.

Vacaliuc, Bogdan [ORNL] [ORNL; Oxley, Paul [Retired] [Retired; Fields, David [ORNL] [ORNL; Kurtz, Dr. Stan [Universidad Nacional Autonoma de Mexico (UNAM)] [Universidad Nacional Autonoma de Mexico (UNAM); Leech, Marcus [Shirleys Bay Radio Astronomy Consortium] [Shirleys Bay Radio Astronomy Consortium

2012-01-01T23:59:59.000Z

350

Public safety radios must pool spectrum  

E-Print Network (OSTI)

The dynamic-spectrum-access research and development community is maturing technologies that will enable radios to share RF spectrum much more intensively. The adoption of DSA technologies by the public-safety community ...

Lehr, William Herndon

351

Low jitter RF distribution system  

DOE Patents (OSTI)

A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

2012-09-18T23:59:59.000Z

352

Effect of radio-frequency bias voltage on the optical and structural properties of hydrogenated amorphous silicon carbide  

SciTech Connect

Hydrogenated amorphous silicon carbide (a-Si{sub 1{minus}x}C{sub x}:H) films have been deposited using the electron cyclotron resonance chemical vapor deposition process under varying negative rf-bias voltage at the substrate. The optical and structural properties of these films are characterized using Rutherford backscattering spectroscopy, transmittance/reflectance spectrophotometry, photothermal deflection spectroscopy, Fourier transform infrared absorption, Raman scattering, and room temperature photoluminescence (PL). These films deposited using a gas mixture of silane, methane, and hydrogen at a constant gas flow ratio showed a slight increase in the carbon fraction x, but very obvious structural transformation, at increasing rf induced bias voltage from {minus}20 to {minus}120 V. Near stoichiometric a-Si{sub 1{minus}x}C{sub x}:H films with a carbon fraction x of almost 0.5 are achieved at low bias voltage range from {minus}20 to {minus}60 V. Visible PL with relatively low efficiency can be observed from such films at room temperature. For larger bias voltages from {minus}80 to {minus}120 V, slightly C-rich a-Si{sub 1{minus}x}C{sub x}:H films (x{gt}0.5) with larger optical gaps are obtained. These films have relatively higher PL efficiency, and the relative quantum efficiency was also found to depend strongly on the optical gap. Structurally, it was found that there is an increase in the hydrogen content and carbon sp{sup 2} bonding in the films at larger bias voltages. The latter leads to an increase in the disorder in the films. The linear relationship observed between the Urbach energy E{sub 0} and B factor in the Tauc equation suggests that the local defects related to microstructural disorder resulting from alloying with carbon dominate the overall defect structure of the films. Substrate biasing is noted to be crucial for the formation of Si{endash}C bonds, as deduced from the Raman scattering results. {copyright} 2001 American Institute of Physics.

Cui, J.; Rusli; Yoon, S. F.; Teo, E. J.; Yu, M. B.; Chew, K.; Ahn, J.; Zhang, Q.; Osipowicz, T.; Watt, F.

2001-06-01T23:59:59.000Z

353

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

354

Design and operation of a rotating drum radio frequency plasma reactor for the modification of free nanoparticles  

SciTech Connect

A rotating drum rf plasma reactor was designed to functionalize the surface of nanoparticles and other unusually shaped substrates through plasma polymerization and surface modification. This proof-of-concept reactor design utilizes plasma polymerized allyl alcohol to add OH functionality to Fe{sub 2}O{sub 3} nanoparticles. The reactor design is adaptable to current plasma hardware, eliminating the need for an independent reactor setup. Plasma polymerization performed on Si wafers, Fe{sub 2}O{sub 3} nanoparticles supported on Si wafers, and freely rotating Fe{sub 2}O{sub 3} nanoparticles demonstrated the utility of the reactor for a multitude of processes. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize the surface of the substrates prior to and after plasma deposition, and scanning electron microscopy was used to verify that no extensive change in the size or shape of the nanoparticles occurred because of the rotating motion of the reactor. The reactor design was also extended to a non-depositing NH{sub 3} plasma modification system to demonstrate the reactor design is effective for multiple plasma processes.

Shearer, Jeffrey C.; Fisher, Ellen R. [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States)

2013-06-15T23:59:59.000Z

355

Effect of substrate temperature on crystal orientation and residual stress in radio frequency sputtered gallium–nitride films  

Science Journals Connector (OSTI)

The crystal orientation and residual stress in gallium nitride(GaN)filmsdeposited on a single-crystal (0001) sapphire substrate using a sputtering system are examined through x-ray diffraction measurements as part of a study of low-temperaturesputtering techniques for GaN. The rf sputtering system has an isolated deposition chamber to prevent contamination with impurities and is expected to produce high-purity nitride films.GaNfilms are deposited at various substrate temperatures and constant gas pressure and input power. This system is found to produce GaNfilms with good crystal orientation with the c axes of GaN crystals oriented normal to the substrate surface. The crystal size of filmsdeposited at high temperature is larger than that deposited at low T s . All films except that deposited at 973 K exhibit compressive residual stress and this residual stress is found to decrease with increasing temperature. Finally the filmdeposited at 973 K was tinged with white and the surface contained numerous microcracks.

Kazuya Kusaka; Takao Hanabusa; Kikuo Tominaga; Noriyoshi Yamauchi

2004-01-01T23:59:59.000Z

356

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

SciTech Connect

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

357

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

358

RF MEMS reconfigurable triangular patch antenna.  

SciTech Connect

A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

Christodoulou, Christos George (The University of New Mexico, Albuquerque, NM); Nordquist, Christopher Daniel; Feldner, Lucas Matthew

2005-07-01T23:59:59.000Z

359

RF MEMS reconfigurable triangular patch antenna.  

SciTech Connect

A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

Nordquist, Christopher Daniel; Christodoulou, Christos George (University of New Mexico, Albuquerque, NM); Feldner, Lucas Matthew

2005-01-01T23:59:59.000Z

360

Experiments with an rf dusty plasma and an external plasma jet  

SciTech Connect

A plasma jet produced in a coaxial plasma gun was aimed at a cloud of dust particles levitated in the sheath of a radio-frequency (rf) plasma produced between two parallel-plate electrodes. A high-speed camera with a side-view on the dust cloud was used to track the dust particles. Several cases of dust motion could be observed. When the jet was parallel with the horizontal electrodes of the rf plasma the dust particles were either pushed out of the trapping region by the plasma jet or were only perturbed from their equilibrium position, oscillating with a frequency of the order of a few kHz. In the first case the trajectory of the dust particles followed the curvature of the sheath. In the second case, when the jet was fired at a small angle with the horizontal electrodes the dust particles hit the bottom electrode and ricocheted back into the sheath. Finally, another situation was observed when the jet perturbed the rf plasma and its sheath and the whole dust crystal fell to the electrode.

Ticos, C. M. [National Institute for Lasers, Plasma and Radiation Physics, 077125 Bucharest (Romania)

2010-12-14T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" 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

High-Power Rf Load  

DOE Patents (OSTI)

A compact high-power RF load comprises a series of very low Q resonators, or chokes [16], in a circular waveguide [10]. The sequence of chokes absorb the RF power gradually in a short distance while keeping the bandwidth relatively wide. A polarizer [12] at the input end of the load is provided to convert incoming TE.sub.10 mode signals to circularly polarized TE.sub.11 mode signals. Because the load operates in the circularly polarized mode, the energy is uniformly and efficiently absorbed and the load is more compact than a rectangular load. Using these techniques, a load having a bandwidth of 500 MHz can be produced with an average power dissipation level of 1.5 kW at X-band, and a peak power dissipation of 100 MW. The load can be made from common lossy materials, such as stainless steel, and is less than 15 cm in length. These techniques can also produce loads for use as an alternative to ordinary waveguide loads in small and medium RF accelerators, in radar systems, and in other microwave applications. The design is easily scalable to other RF frequencies and adaptable to the use of other lossy materials.

Tantawi, Sami G. (San Mateo, CA); Vlieks, Arnold E. (Livermore, CA)

1998-09-01T23:59:59.000Z

362

Theoretical Predictions and Experimental Assessments of the Performance of Alumina RF Windows  

SciTech Connect

Radio frequency (RF) windows are the most likely place for catastrophic failure to occur in input power couplers for particle accelerators. Reliable RF windows are essential for the success of the Accelerator Production of Tritium (APT) program because there are over 1000 windows on the accelerator, and it takes more than one day to recover from a window failure. The goals of this research are to analytically predict the lifetime of the windows, to develop a conditioning procedure, and to evaluate the performance of the RF windows. The analytical goal is to predict the lifetime of the windows. The probability of failure is predicted by the combination of a finite element model of the window, Weibull probabilistic analysis, and fracture mechanics. The window assembly is modeled in a finite element electromagnetic code in order to calculate the electric fields in the window. The geometry (i.e. mesh) and electric fields are input into a translator program to generate the mesh and boundary conditions for a finite element thermal structural code. The temperatures and stresses are determined in the thermal/structural code. The geometry and thermal structural results are input into another translator program to generate an input file for the reliability code. Material, geometry and service data are also input into the reliability code. To obtain accurate Weibull and fatigue data for the analytical model, four point bend tests were done. The analytical model is validated by comparing the measurements to the calculations. The lifetime of the windows is then determined using the reliability code. The analytical model shows the window has a good thermal mechanical design and that fast fracture is unlikely to occur below a power level of 9 Mw. The experimental goal is to develop a conditioning procedure and evaluate the performance of RF windows. During the experimental evaluation, much was learned about processing of the windows to improve the RF performance. Methods of processing included grit blasting and using various coatings.

Karen Ann Cummings

1998-07-01T23:59:59.000Z

363

Rf Feedback free electron laser  

DOE Patents (OSTI)

A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

Brau, Charles A. (Los Alamos, NM); Swenson, Donald A. (Los Alamos, NM); Boyd, Jr., Thomas J. (Los Alamos, NM)

1981-01-01T23:59:59.000Z

364

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

365

RF cavity using liquid dielectric for tuning and cooling  

DOE Patents (OSTI)

A system for accelerating particles includes an RF cavity that contains a ferrite core and a liquid dielectric. Characteristics of the ferrite core and the liquid dielectric, among other factors, determine the resonant frequency of the RF cavity. The liquid dielectric is circulated to cool the ferrite core during the operation of the system.

Popovic, Milorad (Warrenville, IL); Johnson, Rolland P. (Newport News, VA)

2012-04-17T23:59:59.000Z

366

Time dependent evolution of RF-generated non-thermal particle distributions in fusion plasmas  

Science Journals Connector (OSTI)

We describe fully self-consistent time-dependent simulations of radio frequency (RF) generated ion distributions in the ion cyclotron range of frequencies and RF-generated electron distributions in the lower hybrid range of frequencies using combined Fokker–Planck and full wave electromagnetic field solvers. In each regime, the non-thermal particle distributions have been used in synthetic diagnostic codes to compare with diagnostic measurements from experiment, thus providing validation of the simulation capability. The computational intensive simulations require multiple full wave code runs that iterate with a Fokker–Planck code. We will discuss advanced algorithms that have been implemented to accelerate both the massively parallel full wave simulations as well as the iteration with the distribution code. A vector extrapolation method (Sidi A 2008 Comput. Math. Appl. 56) that permits Jacobian-free acceleration of the traditional fixed point iteration technique is used to reduce the number of iterations needed between the distribution and wave codes to converge to self-consistency. The computational burden of the parallel full wave codes has been reduced by using a more efficient two level parallel decomposition that improves the strong scaling of the codes and reduces the communication overhead.

J C Wright; A Bader; L A Berry; P T Bonoli; R W Harvey; E F Jaeger; J-P Lee; A Schmidt; E D'Azevedo; I Faust; C K Phillips; E Valeo

2014-01-01T23:59:59.000Z

367

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

368

Booster Subharmonic RF Capture Design  

NLE Websites -- All DOE Office Websites (Extended Search)

Booster Subharmonic RF Capture Design 1 Booster Subharmonic RF Capture Design Nicholas S. Sereno, 7102002 1.0 Motivation and Requirements Successful operation of the APS storage...

369

E-Print Network 3.0 - argon rf plasma Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

- Princeton Plasma Physics Laboratory Collection: Plasma Physics and Fusion 6 REVERSE-VORTEX PLASMA STABILIZATION: EXPERIMENTS AND NUMERICAL SIMULATION Summary: -Frequency (RF)...

370

Dual-etalon, cavity-ring-down, frequency comb spectroscopy.  

SciTech Connect

The 'dual etalon frequency comb spectrometer' is a novel low cost spectometer with limited moving parts. A broad band light source (pulsed laser, LED, lamp ...) is split into two beam paths. One travels through an etalon and a sample gas, while the second arm is just an etalon cavity, and the two beams are recombined onto a single detector. If the free spectral ranges (FSR) of the two cavities are not identical, the intensity pattern at the detector with consist of a series of heterodyne frequencies. Each mode out of the sample arm etalon with have a unique frequency in RF (radio-frequency) range, where modern electronics can easily record the signals. By monitoring these RF beat frequencies we can then determine when an optical frequencies is absorbed. The resolution is set by the FSR of the cavity, typically 10 MHz, with a bandwidth up to 100s of cm{sup -1}. In this report, the new spectrometer is described in detail and demonstration experiments on Iodine absorption are carried out. Further we discuss powerful potential next generation steps to developing this into a point sensor for monitoring combustion by-products, environmental pollutants, and warfare agents.

Strecker, Kevin E.; Chandler, David W.

2010-10-01T23:59:59.000Z

371

COLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY  

E-Print Network (OSTI)

COLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY Yu.M. Aliev1 , I an interest in mechanisms of electron heating and power deposition in the plasma main- tained by radio parameters. Due to the large value of the mean free path (MFP) the main mechanism of electron heating turns

Kaganovich, Igor

372

Spectroscopy of Rf257  

Science Journals Connector (OSTI)

The isotope Rf257 was produced in the fusion-evaporation reaction Pb208(Ti50,n)Rf257. Reaction products were separated and identified by mass. Delayed spectroscopy of Rf257 and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on ? hindrance factors. The excitation energy of the 1/2+[620] configuration in No253 is proposed. The energy of this 1/2+ state in a series of N=151 isotones increases with nuclear charge, reflecting an increase in the N=152 gap. This gap is deduced to grow substantially from 850 to 1400 keV between Z=94 and 102. An isomeric state in Rf257, with a half-life of 160-31+42??s, was discovered by detecting internal conversion electrons followed by ? decay. It is interpreted as a three-quasiparticle high-K isomer. A second group of internal conversion electrons, with a half-life of 4.1-1.3+2.4 s, followed by ? decay, was also observed. These events might originate from the decay of excited states in Lr257, populated by electron-capture decay of Rf257. Fission of Rf257 was unambiguously detected, with a branching ratio of bRfSF=0.02±0.01.

J. Qian; A. Heinz; T. L. Khoo; R. V. F. Janssens; D. Peterson; D. Seweryniak; I. Ahmad; M. Asai; B. B. Back; M. P. Carpenter; A. B. Garnsworthy; J. P. Greene; A. A. Hecht; C. L. Jiang; F. G. Kondev; T. Lauritsen; C. J. Lister; A. Robinson; G. Savard; R. Scott; R. Vondrasek; X. Wang; R. Winkler; S. Zhu

2009-06-22T23:59:59.000Z

373

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

374

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas  

Science Journals Connector (OSTI)

A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique large-volume ( 1000 ? cm 3 ) high electron density (on the order of 10 11 – 12 ? cm ? 3 ) 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region (30 cm) and the rf power budget is 5 ? W / cm 3 . Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter waveinterferometry. Optical emission spectroscopy(OES) aided by SPECAIR a special OES simulation program for air-constituent plasmas is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400 – 4600 ± 100 ? K are obtained from the emission spectra from the N 2 ( 2 + ) and N 2 + ( 1 ? ) transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density utilizing millimeter waveinterferometry the electron temperature of the 760 Torr nitrogen plasma is found to be 8700 ± 100 ? K ( 0.75 ± 0.1 ? eV ) . Therefore the plasma deviates significantly from local thermal equilibrium.

Siqi Luo; C. Mark Denning; John E. Scharer

2008-01-01T23:59:59.000Z

375

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas  

SciTech Connect

A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume (1000 cm{sup 3}), high electron density (on the order of 10{sup 11-12} cm{sup -3}), 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region (30 cm), and the rf power budget is 5 W/cm{sup 3}. Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter wave interferometry. Optical emission spectroscopy (OES) aided by SPECAIR, a special OES simulation program for air-constituent plasmas, is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400-4600{+-}100 K are obtained from the emission spectra from the N{sub 2}(2+) and N{sub 2}{sup +}(1-) transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density, utilizing millimeter wave interferometry, the electron temperature of the 760 Torr nitrogen plasma is found to be 8700{+-}100 K (0.75{+-}0.1 eV). Therefore, the plasma deviates significantly from local thermal equilibrium.

Luo Siqi; Denning, C. Mark; Scharer, John E. [Electrical and Computer Engineering, University of Wisconsin--Madison, Madison, Wisconsin 53705 (United States)

2008-07-01T23:59:59.000Z

376

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

377

RF Interconnection and Switching  

Science Journals Connector (OSTI)

The components that connect, interface, transfer, and filter RF energy within a given system—or between systems—are critical elements in the operation of vacuum tube devices. Such hardware, usually passive, de...

Jerry C. Whitaker

1994-01-01T23:59:59.000Z

378

Enhancement of RF Breakdown Threshold of Microwave Cavities by Magnetic Insulation  

SciTech Connect

Limitations on the maximum achievable accelerating gradient of microwave cavities can influence the performance, length, and cost of particle accelerators. Gradient limitations are believed to be initiated by electron emission from the cavity surfaces. Here, we show that field emission is effectively suppressed by applying a tangential magnetic field to the cavity walls, so higher gradients can be achieved. Numerical simulations indicate that the magnetic field prevents electrons leaving these surfaces and subsequently picking up energy from the electric field. Our results agree with current experimental data. Two specific examples illustrate the implementation of magnetic insulation into prospective particle accelerator applications. The ultimate goal of several research efforts is to integrate high-gradient radio-frequency (rf) structures into next generation particle accelerators. For instance, the Muon Accelerator Program is looking at developing low-frequency cavities for muon cooling, and the International Linear Collider is optimizing the performance of 1.3 GHz rf structures aimed at designing a 1 TeV electron-positron collider. Furthermore, the High Gradient RF Collaboration is examining high frequency (f > 10 GHz) structures intended for an electron-positron collider operating at energies in the TeV range. In all this research, the accelerating gradient will be one of the crucial parameters affecting their design, construction, and cost. Limitations from rf breakdown strongly influence the development of accelerators since it limits the machine's maximum gradient. The emission of electrons from the cavity surfaces seemingly is a necessary stage in the breakdown process, acting either as a direct cause of breakdown or as precursor for other secondary effects. Typically, electron currents arise from sharp edges or cracks on the cavities surfaces, where the strength of the electric field is strongly enhanced compared to that of the nominal field when the surfaces of the cavity are perfect planes. Subsequently, a stream of emitted electrons can be accelerated by the rf electric field toward the opposing cavity walls. Upon impact, they heat a localized region, resulting in the eventual breakdown by a variety of secondary mechanisms. Therefore, it is advantageous to develop techniques that could suppress field emission within rf cavities. It has been proposed that high voltages up to about a gigavolt range may be sustained in voltage transformers, by adopting the principle of magnetic insulation in ultrahigh vacuum. The basic idea is to suppress field emission by applying a suitably directed magnetic field of sufficient strength to force the electrons orbits back on to the rf emitting surface. More recently, it was shown that magnetic insulation could be very effective in suppressing field emission and multipacting in rectangular coupler waveguides. Hence, the question arises whether the same principle is applicable to rf accelerating structures. In this Letter, we shall consider application of the concept to low-frequency (201-805 MHz) muon accelerator cavities.

Stratakis, D.; Gallardo, J.; Palmer, R.B.

2011-03-28T23:59:59.000Z

379

RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES  

SciTech Connect

Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Part of the problem is that RF breakdown in an evacuated cavity involves a complex mixture of effects, which include the geometry, metallurgy, and surface preparation of the accelerating structures and the make-up and pressure of the residual gas in which plasmas form. Studies showed that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas, as needed for muon cooling channels, without the need for long conditioning times, even in the presence of strong external magnetic fields. This positive result was expected because the dense gas can practically eliminate dark currents and multipacting. In this project we used this high pressure technique to suppress effects of residual vacuum and geometry that are found in evacuated cavities in order to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. One of the interesting and useful outcomes of this project was the unanticipated collaborations with LANL and Fermilab that led to new insights as to the operation of evacuated normal-conducting RF cavities in high external magnetic fields. Other accomplishments included: (1) RF breakdown experiments to test the effects of SF6 dopant in H2 and He gases with Sn, Al, and Cu electrodes were carried out in an 805 MHz cavity and compared to calculations and computer simulations. The heavy corrosion caused by the SF6 components led to the suggestion that a small admixture of oxygen, instead of SF6, to the hydrogen would allow the same advantages without the corrosion in a practical muon beam line. (2) A 1.3 GHz RF test cell capable of operating both at high pressure and in vacuum with replaceable electrodes was designed, built, and power tested in preparation for testing the frequency and geometry effects of RF breakdown at Argonne National Lab. At the time of this report this cavity is still waiting for the 1.3 GHz klystron to be available at the Wakefield Test Facility. (3) Under a contract with Los Alamos National Lab, an 805 MHz RF test cavity, known as the All-Seasons Cavity (ASC), was designed and built by Muons, Inc. to operate either at high pressure or under vacuum. The LANL project to use the (ASC) was cancelled and the testing of the cavity has been continued under the grant reported on here using the Fermilab Mucool Test Area (MTA). The ASC is a true pillbox cavity that has performed under vacuum in high external magnetic field better than any other and has demonstrated that the high required accelerating gradients for many muon cooling beam line designs are possible. (4) Under ongoing support from the Muon Acceleration Program, microscopic surface analysis and computer simulations have been used to develop models of RF breakdown that apply to both pressurized and vacuum cavities. The understanding of RF breakdown will lead to better designs of RF cavities for many applications. An increase in the operating accelerating gradient, improved reliability and shorter conditioning times can generate very significant cost savings in many accelerator projects.

Johnson, Rolland

2014-09-21T23:59:59.000Z

380

Rf beam control for the AGS Booster  

SciTech Connect

RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.

Brennan, J.M.

1994-09-26T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" from the National Library of EnergyBeta (NLEBeta).
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381

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

382

ISG8-RF Sources  

NLE Websites -- All DOE Office Websites (Extended Search)

RF Sources - (WG3) RF Sources - (WG3) Orange Rm Yong Ho Chin, Christopher Nantista, and Sami G. Tantawi Parallel Sessions: Working Groups: WG1: Parameters, Design, Instrumentation and Tuning WG2: Damping Rings and ATF WG3: RF Sources WG4:Structures WG5: Ground Motion; Site Requirements and Investigations Monday Morning 9:00-10:30 Plenary Coffee Break 11:00-12:00 Planning Session. Monday Afternoon 13:30-15:30 High Gradient Issues (Joint with working group 4) Coffee Break 16:00-16:30 The 8-Pack Project -- D. Atkinson 16:30-17:30 High Gradient Issues and Discussions Continued. Tuesday Morning 9:30-10:30 Klystrons 9:30-10:00 Status of PPM Klystron Development for JLC -- Y. H. Chin 10:00-10:30 Design of 150MW Multi-Beam Klystron -- S. Matsumoto Coffee Break 11:00-11:30 Klystron Development at SLAC -- G. Caryotakis

383

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

384

Can RF help CMOS processors?  

E-Print Network (OSTI)

FOR C OMMUNICATIONS Can RF Help CMOS Processors? Eran SocherRF communication can help increase the wired communicationaluminum and low-K dielectrics help reduce wire delay but do

Socher, Eran; Chang, Mau-Chung Frank

2007-01-01T23:59:59.000Z

385

Effect of dual frequency on the plasma characteristics in an internal linear inductively coupled plasma source  

SciTech Connect

An internal-type linear inductive antenna, referred to as a ''double comb-type antenna,'' was used as a large area plasma source with a substrate size of 880x660 mm{sup 2} (fourth generation glass size). The effects of the dual frequency (2 and 13.56 MHz) radio frequency (rf) power to the antenna as well as the power ratio on the plasma characteristics were investigated. High-density plasma on the order of 1.7x10{sup 11} cm{sup -3} could be obtained with a dual frequency power of 5 kW (13.56 MHz) and 1 kW (2 MHz) at a pressure of 15 mTorr Ar. This plasma density was lower than that obtained for the double comb-type antenna using a single frequency alone (5 kW, 13.56 MHz). However, the use of the dual frequency with a rf power ratio of approximately 1(2 MHz):5(13.56 MHz) showed better plasma uniformity than that obtained using the single frequency. Plasma uniformity of 6.1% could be obtained over the substrate area. Simulations using FL2L code confirmed the improvement in the plasma uniformity using the dual frequency to the double comb-type antenna.

Kim, K. N.; Lim, J. H.; Yeom, G. Y.; Lee, S. H.; Lee, J. K. [Department of Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 440-746 (Korea, Republic of); Department of Electronic and Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2006-12-18T23:59:59.000Z

386

Chameleonic Radio Technical Memo No. 23  

E-Print Network (OSTI)

Hasan, M. Harun, and C.R. Anderson October 5, 2007 Bradley Dept. of Electrical & Computer Engineering S.W. Ellingson , S.M. Shajedul Hasan, M. Harun, and C.R. Anderson October 7, 2007 Contents 1 Wideband RF Downconverter for the NIJ Public Safety Radio," S.M. Shajedul Hasan and S.W. Ellingson

Ellingson, Steven W.

387

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

388

Generation of Electron Bunches at Low Repetition Rates Using a Beat-Frequency Technique  

SciTech Connect

Even at a continuous wave facility such as CEBAF at Jefferson Lab, an electron beam with long time intervals (tens of ns) between individual bunches can be useful, for example to isolate sources of background via time of flight detection or to measure the energy of neutral particles that cannot be separated with a magnetic field. This paper describes a demonstrated method to quickly and easily deliver bunches with repetition rates of 20 to 100 MHz corresponding to time intervals between 10 to 50 ns (respectively). This is accomplished by changing the ON/OFF frequency of the RF-pulsed drive laser by a small amount (?f/f < 20%), resulting in a bunch frequency equal to the beat frequency between the radio frequencies of the drive laser and the photoinjector chopper system.

Matt Poelker; Joseph Grames; John Hansknecht; Reza Kazimi; John Musson

2007-05-01T23:59:59.000Z

389

Particle-In-Cell/Monte Carlo Simulation of Ion Back BomBardment in a High Average Current RF Photo-Gun  

E-Print Network (OSTI)

High Average Current RF Photo-Gun J. Qiang Lawrence Berkeleyradio-frequency (RF) photo-gun using a particle-in-cell/ion motion inside the gun so that the ion power deposition

Qiang, J.

2010-01-01T23:59:59.000Z

390

Production of higher silanes in radio frequency SiH{sub 4} and H{sub 2}-SiH{sub 4} plasmas  

SciTech Connect

Stable gases produced in SiH{sub 4} and H{sub 2}-SiH{sub 4}, capacitively coupled rf discharges operated at typical device-production conditions, were investigated by quadrupole mass spectrometry. The production of disilane and trisilane and the depletion of silane and pressure change were measured during consecutive short discharges. Dissociation rate constants and branching ratios for higher-silane production are obtained from the time-dependent densities. The influence of suspended Si particles on stable-gas production is found to be negligible, by changing the duration of individual discharges and thereby the particle densities and sizes. We have also observed pyrolitic decay of disilane and trisilane at 200 deg. C, although this is negligible under normal reactor conditions.

Horvath, P.; Rozsa, K.; Gallagher, A. [JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, Colorado 80309-0440 (United States)

2004-12-15T23:59:59.000Z

391

ARIANNA: A radio detector array for cosmic neutrinos on the Ross Ice Shelf  

E-Print Network (OSTI)

ARIANNA (The Antarctic Ross Ice Shelf Antenna Neutrino Array) is a proposed 100 km^3 detector for ultra-high energy (above 10^17 eV) astrophysical neutrinos. It will study the origins of ultra-high energy cosmic rays by searching for the neutrinos produced when these cosmic rays interact with the cosmic microwave background. Over 900 independently operating stations will detect the coherent radio Cherenkov emission produced when astrophysical neutrinos with energy above 10^17 eV interact in the Antarctic Ross Ice Shelf. Each station will use 8 log periodic dipole antennas to look for short RF pulses, with the most important frequencies between 80 MHz and 1 GHz. By measuring the pulse polarization and frequency spectrum, the neutrino arrival direction can be determined.

Klein, Spencer R

2012-01-01T23:59:59.000Z

392

Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry  

SciTech Connect

New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.

Wilcox, R.; Byrd, J. M.; Doolittle, L.; Huang, G.; Staples, J. W.

2010-01-02T23:59:59.000Z

393

RF current sensor  

DOE Patents (OSTI)

An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

Moore, James A. (Powell, TN); Sparks, Dennis O. (Maryville, TN)

1998-11-10T23:59:59.000Z

394

RF propagation in an HVAC duct system: impulse response characteristics of the channel  

E-Print Network (OSTI)

RF propagation in an HVAC duct system: impulse response characteristics of the channel Pavel V, the heating, ventilation, and air conditioning (HVAC) duct system in buildings is a complex network of hollow at RF and microwave frequencies of com- mon interest. HVAC ducts can be used as a wireless communication

Stancil, Daniel D.

395

Microsoft PowerPoint - rf_5year_review  

NLE Websites -- All DOE Office Websites (Extended Search)

RF Research Program RF Research Program DOE Review of C-Mod Five-Year Proposal May 13-14, 2003 MIT PSFC Presented by Steve J.Wukitch Outline: 1. Overview of the RF Program 2. Five-year plan Overview of the RF Program AT: validate steady state operation with target parameters β N = 3, I non = 100%, I BS ~ 70%, H 89 ~ 2.5, for t pulse > t L/R . BPX: demonstrate the viability of high performance plasmas, B T = 8T, I p = 2 MA, P = 6 MW, H 89 ≥ 2, Z eff < 1.5. B T = 5.4T, I p = 1.4 MA, P = 6 MW, H 89 = 2 (ITER demo) Exclusively use RF power for auxiliary heating and current drive. variable variable fixed Phase 2 x 4 Strap 4 Strap 2 x 2 Strap Antenna 4 MW 40-80 MHz J-port 2 x 4 MW 2 x 2 MW Power 40-80 MHz ~ 80 MHz Frequency E & J-port D & E-port 2005-2008 2002-2005 4.6 GHz 4.6 GHz Frequency 16 x 250 kW

396

Development of internal-antenna-driven large-area RF plasma sources using multiple low-inductance antenna units  

Science Journals Connector (OSTI)

Large-area and high-density radio frequency (RF) plasmas at 13.56 \\{MHz\\} have been produced by inductive coupling of internal-type low-inductance antenna units. The present study has been carried out to develop the basic discharge techniques which can be applied to production of meter-scale large-area and/or large-volume plasma sources with high density for a variety of plasma processes. The plasma source could be operated stably to attain plasma density as high as 1×1012 cm?3 at argon pressures of approximately 1 Pa. It has been demonstrated that high plasma density can be obtained efficiently using the low-inductance internal antenna configuration with effectively suppressed electrostatic coupling. Discharge experiments in a meter-scale chamber demonstrated uniform plasma production with densities as high as 6×1011 cm?3 at an argon pressure of 1.3 Pa and a RF power of 4 kW.

Y. Setsuhara; T. Shoji; A. Ebe; S. Baba; N. Yamamoto; K. Takahashi; K. Ono; S. Miyake

2003-01-01T23:59:59.000Z

397

High-Efficiency Resonant RF Spin Rotator with Broad Phase Space Acceptance for Pulsed Polarized Cold Neutron Beams  

E-Print Network (OSTI)

We have developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to RF neutron spin flippers based on adiabatic fast passage. The spin rotator does not change the kinetic energy of the neutrons and leaves the neutron beam phase space unchanged to high precision. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically-polarized 3He neutron spin filters. The efficiency of the spin rotator was measured to be 98.0+/-0.8% on resonance for neutron energies from 3.3 to 18.4 meV over the full phase space of the beam. As an example of the application of this device to an experiment we describe the integration of the RF spin rotator into an apparatus to search for the small parity-violating asymmetry A_gamma in polarized cold neutron capture on para-hydrogen by the NPDGamma collaboration at LANSCE.

P. -N. Seo; L. Barron-Palos; J. D. Bowman; T. E. Chupp; C. Crawford; M. Dabaghyan; M. Dawkins; S. J. Freedman; T. Gentile; M. T. Gericke; R. C. Gillis; G. L. Greene; F. W. Hersman; G. L. Jones; M. Kandes; S. Lamoreaux; B. Lauss; M. B. Leuschner; R. Mahurin; M. Mason; J. Mei; G. S. Mitchell; H. Nann; S. A. Page; S. I. Penttila; W. D. Ramsay; A. Salas Bacci; S. Santra; M. Sharma; T. B. Smith; W. M. Snow; W. S. Wilburn; H. Zhu

2007-10-15T23:59:59.000Z

398

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

399

Locating RF Emitters with Large UAV Teams Paul Scerri, Robin Glinton, Sean Owens and Katia Sycara  

E-Print Network (OSTI)

Locating RF Emitters with Large UAV Teams Paul Scerri, Robin Glinton, Sean Owens and Katia Sycara efficient way for a team of UAVs with Received Signal Strength Indicator (RSSI) sen- sors to locate radio locations requires integrating multiple signals from different UAVs into a Bayesian filter, hence requir

Scerri, Paul

400

Analytical model for ion angular distribution functions at rf biased surfaces with collisionless plasma sheaths  

E-Print Network (OSTI)

Analytical model for ion angular distribution functions at rf biased surfaces with collisionless plasma sheaths Laxminarayan L. Rajaa) Department of Aerospace Engineering and Engineering Mechanics The article presents an analytical model for evaluation of ion angular distribution functions IADFs at a radio

Raja, Laxminarayan L.

Note: This page contains sample records for the topic "rf radio frequency" 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

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

402

EXPERIMENTAL STUDIES OF RF BREAKDOWNS IN THE COUPLER OF THE TTF RF GUN  

E-Print Network (OSTI)

EXPERIMENTAL STUDIES OF RF BREAKDOWNS IN THE COUPLER OF THE TTF RF GUN J.-P. Carneiro , S I, the RF gun of the TESLA Test Facility (TTF) has been operated with long RF pulses (up to 0.9 ms Fermilab has developed and delivered to DESY two RF guns for the operation of phase 1 of the TESLA Test

403

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"

404

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

405

Software-defined Radio Based Wireless Tomography: Experimental Demonstration and Verification  

SciTech Connect

This letter presents an experimental demonstration of software-defined-radio-based wireless tomography using computer-hosted radio devices called Universal Software Radio Peripheral (USRP). This experimental brief follows our vision and previous theoretical study of wireless tomography that combines wireless communication and RF tomography to provide a novel approach to remote sensing. Automatic data acquisition is performed inside an RF anechoic chamber. Semidefinite relaxation is used for phase retrieval, and the Born iterative method is utilized for imaging the target. Experimental results are presented, validating our vision of wireless tomography.

Bonior, Jason D [ORNL; Hu, Zhen [Tennessee Technological University; Guo, Terry N. [Tennessee Technological University; Qiu, Robert C. [Tennessee Technological University; Browning, James P. [United States Air Force Research Laboratory, Wright-Patterson Air Force Base; Wicks, Michael C. [University of Dayton Research Institute

2015-01-01T23:59:59.000Z

406

Wafer-Scale Graphene Integrated Circuit  

Science Journals Connector (OSTI)

...broadband radio-frequency mixer at frequencies up to 10 gigahertz...electronics and radio-frequency (RF) applications (1...vulnerability to damage in plasma processing. Thus...communication systems. Two high-frequency signals, an RF...

Yu-Ming Lin; Alberto Valdes-Garcia; Shu-Jen Han; Damon B. Farmer; Inanc Meric; Yanning Sun; Yanqing Wu; Christos Dimitrakopoulos; Alfred Grill; Phaedon Avouris; Keith A. Jenkins

2011-06-10T23:59:59.000Z

407

E-Print Network 3.0 - acoustic wave-assisted scanning Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

Key words: frequency-dependent backscatter... sonographic scanning system are made from radio frequency (RF) echo signals. The RF echo signals are ... Source: Illinois at...

408

MULTIMOMENT RADIO TRANSIENT DETECTION  

SciTech Connect

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

409

Compact RF resonator for cryogenic ion traps  

E-Print Network (OSTI)

We report on the investigation and implementation of a lumped-component, radio-frequency resonator used in a cryogenic vacuum environment to drive an ion trap. The resonator was required to achieve the voltages necessary to trap (about 100 V), while dissipating as little power as possible (< 250 mW). Ultimately a voltage gain of 100 was measured at 5.7 K. Single calcium ions were confined in a trap driven by this device, providing proof of successful resonator operation at low temperature.

D. Gandolfi; M. Niedermayr; M. Kumph; M. Brownnutt; R. Blatt

2012-04-23T23:59:59.000Z

410

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

411

Cryogenic vacuumm RF feedthrough device  

DOE Patents (OSTI)

A cryogenic vacuum rf feedthrough device comprising: 1) a probe for insertion into a particle beam; 2) a coaxial cable comprising an inner conductor and an outer conductor, a dielectric/insulating layer surrounding the inner conductor, the latter being connected to the probe for the transmission of higher mode rf energy from the probe; and 3) a high thermal conductivity stub attached to the coaxial dielectric about and in thermal contact with the inner conductor which high thermal conductivity stub transmits heat generated in the vicinity of the probe efficiently and radially from the area of the probe and inner conductor all while maintaining useful rf transmission line characteristics between the inner and outer coaxial conductors.

Wu, Genfa (Yorktown, VA); Phillips, Harry Lawrence (Hayes, VA)

2008-12-30T23:59:59.000Z

412

radioCherenkov.dvi  

NLE Websites -- All DOE Office Websites (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

413

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

414

Note on RF Photo-Cathode Gun  

E-Print Network (OSTI)

Emittances in Laser-Driven RF Guns", Proc. 1988 Linear Acc.Palmer, "Preliminary Study of Gun Emittance Correction", BNLLaser-Driven RF Electron Guns", Nuc1. ln stt. Meth. , A275,

Kim, Kwang-Je

2010-01-01T23:59:59.000Z

415

Simulation of synchrotron motion with rf noise  

SciTech Connect

The theoretical formulation is described that is behind an algorithm for synchrotron phase-space tracking with rf noise and some preliminary simulation results of bunch diffusion under rf noise obtained by actual tracking.

Leemann, B.T.; Forest, E.; Chattopadhyay, S.

1986-08-01T23:59:59.000Z

416

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

417

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

418

Comparison of Measured and Calculated Coupling between a Waveguide and an RF Cavity Using CST Microwave Studio  

SciTech Connect

Accurate predications of RF coupling between an RF cavity and ports attached to it have been an important study subject for years for RF coupler and higher order modes (HOM) damping design. We report recent progress and a method on the RF coupling simulations between waveguide ports and RF cavities using CST Microwave Studio in time domain (Transit Solver). Comparisons of the measured and calculated couplings are presented. The simulated couplings and frequencies agree within {approx} 10% and {approx} 0.1% with the measurements, respectively. We have simulated couplings with external Qs ranging from {approx} 100 to {approx} 100,000, and confirmed with measurements. The method should also work well for higher Qs, and can be easily applied in RF power coupler designs and HOM damping for normal-conducting and superconducting cavities.

J. Shi; H. Chen; S. Zheng; D. Li; R.A. Rimmer; H. Wang

2006-06-26T23:59:59.000Z

419

Fabrication process changes for performance improvement of an RF MEMS resonator : conformable contact lithography, Moiré alignment, and chlorine dry etching  

E-Print Network (OSTI)

This thesis presents fabrication process improvements for a RF MEMS resonator for the purpose of improving the quality factor (Q) and extending the frequency range. The process changes include the use of conformable contact ...

Sakai, Mark

2005-01-01T23:59:59.000Z

420

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

Note: This page contains sample records for the topic "rf radio frequency" 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

SPL RF Coupler Cooling Efficiency  

E-Print Network (OSTI)

Energy saving is an important challenge in accelerator design. In this framework, reduction of heat loads in a cryomodule is of fundamental importance due to the small thermodynamic efficiency of cooling at low temperatures. In particular, care must be taken during the design of its critical components (e.g. RF couplers, coldwarm transitions). In this framework, the main RF coupler of the Superconducting Proton Linac (SPL) cryomodule at CERN will not only be used for RF powering but also as the main mechanical support of the superconducting cavities. These two functions have to be accomplished while ensuring the lowest heat in-leak to the helium bath at 2 K. In the SPL design, the RF coupler outer conductor is composed of two walls and cooled by forced convection with helium gas at 4.5 K. Analytical, semi-analytical and numerical analyses are presented in order to defend the choice of gas cooling. Temperature profiles and thermal performance have been evaluated for different operating conditions; a sensitivit...

Bonomi, R; Montesinos, E; Parma, V; Vande Craen, A

2014-01-01T23:59:59.000Z

422

Josephson device with a matched rf source  

SciTech Connect

Analog simulation of a resistance-shunted ac Josephson junction coupled to an rf source with matching impedance reveals (1) added structure in the device's V-I curve even when the source is quiescent and (2) rf-induced steps with peak amplitudes between those produced by voltage and current rf sources. Both results are consistent with experimental data.

Longacre, A. Jr.

1980-03-01T23:59:59.000Z

423

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

424

High Gradient Acceleration in a 17 GHz Photocathode RF Gun* S. C. Chen, J. Gonichon, 1;. C-L. Lin, R. J. Temkin, S. Trotz, B. G. Danly, and J. S. Wurtele  

E-Print Network (OSTI)

High Gradient Acceleration in a 17 GHz Photocathode RF Gun* S. C. Chen, J. Gonichon, 1;. C-L. Lin.icle acceleration at high mi- ccowave (RF) frequencies are under study at hIIT. The 17 GHz photocathode RF gun has, efforts have been made recent,ly t,o creat,e novel electron beam sources.[l] While existing RF guns

Wurtele, Jonathan

425

Application of new simulation algorithms for modeling rf diagnostics of electron clouds  

SciTech Connect

Traveling wave rf diagnostics of electron cloud build-up show promise as a non-destructive technique for measuring plasma density and the efficacy of mitigation techniques. However, it is very difficult to derive an absolute measure of plasma density from experimental measurements for a variety of technical reasons. Detailed numerical simulations are vital in order to understand experimental data, and have successfully modeled build-up. Such simulations are limited in their ability to reproduce experimental data due to the large separation of scales inherent to the problem. Namely, one must resolve both rf frequencies in the GHz range, as well as the plasma modulation frequency of tens of MHz, while running for very long simulations times, on the order of microseconds. The application of new numerical simulation techniques allow us to bridge the simulation scales in this problem and produce spectra that can be directly compared to experiments. The first method is to use a plasma dielectric model to measure plasma-induced phase shifts in the rf wave. The dielectric is modulated at a low frequency, simulating the effects of multiple bunch crossings. This allows simulations to be performed without kinetic particles representing the plasma, which both speeds up the simulations as well as reduces numerical noise from interpolation of particle charge and currents onto the computational grid. Secondly we utilize a port boundary condition model to simultaneously absorb rf at the simulation boundaries, and to launch the rf into the simulation. This method improves the accuracy of simulations by restricting rf frequencies better than adding an external (finite) current source to drive rf, and absorbing layers at the boundaries. We also explore the effects of non-uniform plasma densities on the simulated spectra.

Veitzer, Seth A.; Smithe, David N.; Stoltz, Peter H. [Tech-X Corporation, Boulder, CO, 80303 (United States)

2012-12-21T23:59:59.000Z

426

Loading a planar RF Paul Trap from a cold Yb? source  

E-Print Network (OSTI)

In this thesis, we demonstrate a functioning planar radio frequency, three-rod Paul Trap, loaded with Yb+ ions that have been photoionized from a source of neutral atoms, which were cooled in a magneto-optical trap. Planar ...

Shields, Brendan John

2006-01-01T23:59:59.000Z

427

RESULTS FROM A DEMONSTRATION OF RF-BASED UF6 CYLINDER ACCOUNTING AND TRACKING SYSTEM INSTALLED AT A USEC FACILITY  

SciTech Connect

Approved industry-standard cylinders are used globally for storing and transporting uranium hexafluoride (UF{sub 6}) at uranium enrichment plants and processing facilities. To verify that no diversion or undeclared production of nuclear material involving UF{sub 6} cylinders at the facility has occurred, the International Atomic Energy Agency (IAEA) conducts periodic, labor-intensive physical inspections to validate facility records, cylinder identities, and cylinder weights. A reliable cylinder monitoring system that would improve overall inspector effectiveness would be a significant improvement to the current international safeguards inspection regime. Such a system could include real-time unattended monitoring of cylinder movements, situation-specific rules-based event detection algorithms, and the capability to integrate with other types of safeguards technologies. This type of system could provide timely detection of abnormal operational activities that may be used to ensure more appropriate and efficient responses by the IAEA. A system of this type can reduce the reliance on paper records and have the additional benefit of facilitating domestic safeguards at the facilities at which it is installed. A radio-frequency (RF)-based system designed to track uranium hexafluoride (UF{sub 6}) cylinders during processing operations was designed, assembled, and tested at the United States Enrichment Corporation (USEC) facility in Portsmouth, Ohio, to determine the operational feasibility and durability of RF technology. The overall objective of the effort was to validate the robustness of RF technology for potential use as a future international safeguards tool for tracking UF6 cylinders at uranium-processing facilities. The results to date indicate that RF tags represent a feasible technique for tracking UF{sub 6} cylinders in operating facilities. Additional work will be needed to improve the operational robustness of the tags for repeated autoclave processing and to add tamper-indicating and data authentication features to some of the pertinent system components. Future efforts will focus on these needs along with implementing protocols relevant to IAEA safeguards. The work detailed in this report demonstrates the feasibility of constructing RF devices that can survive the operational rigors associated with the transportation, storage, and processing of UF6 cylinders. The system software specially designed for this project is called Cylinder Accounting and Tracking System (CATS). This report details the elements of the CATS rules-based architecture and its use in safeguards-monitoring and asset-tracking applications. Information is also provided on improvements needed to make the technology ready, as well as options for improving the safeguards aspects of the technology. The report also includes feedback from personnel involved in the testing, as well as individuals who could utilize an RF-based system in supporting the performance of their work. The system software was set up to support a Mailbox declaration, where a declaration can be made either before or after cylinder movements take place. When the declaration is made before cylinders move, the operators must enter this information into CATS. If the IAEA then shows up unexpectedly at the facility, they can see how closely the operational condition matches the declaration. If the declaration is made after the cylinders move, this provides greater operational flexibility when schedules are interrupted or are changed, by allowing operators to declare what moves have been completed. The IAEA can then compare where cylinders are with where CATS or the system says they are located. The ability of CATS to automatically generate Mailbox declarations is seen by the authors as a desirable feature. The Mailbox approach is accepted by the IAEA but has not been widely implemented (and never in enrichment facilities). During the course of this project, we have incorporated alternative methods for implementation.

Pickett, Chris A [ORNL; Kovacic, Donald N [ORNL; Morgan, Jim [Innovative Solutions; Younkin, James R [ORNL; Carrick, Bernie [USEC; Ken, Whittle [USEC; Johns, R E [Pacific Northwest National Laboratory (PNNL)

2008-09-01T23:59:59.000Z

428

Performance of Magnesium Cathode in the S Band RF Gun  

SciTech Connect

In this paper, we present the preliminary results of the performance of magnesium cathode in a high frequency RF gun. The quantum efficiency of magnesium showed a dramatic improvement upon laser cleaning, increasing from 10{sup -5} to 4x10{sup -4} after two hours of cleaning. The spatial uniformity of emission also improved from a spot to spot variation of 10 to a variation of 2. Measurements with charges >1 nC indicate that the transient variation of the field due to the shielding effect of the electron in the vicinity of the cathode may play a critical role in the efficient extraction of electrons. Comprehensive theory that includes the electron emission in the presence of a time dependent Schottky effect and RF effects will be discussed.

Srinivasan-Rao, T.; /Brookhaven; Palmer, D.T.; /SLAC; Ben-Zvi, I.; /Brookhaven; Miller, R.H.; /SLAC; Wang, X.J.; Woodle, M.; /Brookhaven

2011-09-01T23:59:59.000Z

429

Single electron beam rf feedback free electron laser  

DOE Patents (OSTI)

A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

Brau, C.A.; Stein, W.E.; Rockwood, S.D.

1981-02-11T23:59:59.000Z

430

RF System Modeling for the CEBAF Energy Upgrade  

SciTech Connect

An RF system model, based on MATLAB/SIMULINK, has been developed for analyzing the basic characteristics of the low level RF (LLRF) control system being designed for the CEBAF 12 GeV Energy Upgrade. In our model, a typical passband cavity representation is simplified to in-phase and quadrature (I&Q) components. Lorentz Force and microphonic detuning are incorporated as a new quadrature carrier frequency (frequency modulation). Beam is also represented as in-phase and quadrature components and superpositioned with the cavity field vector. Signals pass through two low pass filters, where the cutoff frequency is equal to half of the cavity bandwidth, then they are demodulated using the same detuning frequency. Because only baseband I&Q signals are calculated, the simulation process is very fast when compared to other controller-cavity models. During the design process we successfully analyzed gain requirements vs. field stability for different superconducting cavity microphonic backgrounds and Lorentz Force coefficients. Moreover, we were able to evaluate different types of a LLRF system’s control algorithm: GDR (Generator Driven Resonator) and SEL (Self Excited Loop) [1] as well as klystron power requirements for different cavities and beam loads.

Tomasz Plawski, J. Hovater

2009-05-01T23:59:59.000Z

431

RF Systems in a Neutrino Factory  

SciTech Connect

Based on existing sources, I compile parameters for the RF systems for a neutrino factory which accelerates to 10 GeV.

Berg J. S.

2012-09-07T23:59:59.000Z

432

RF Micro Devices | Open Energy Information  

Open Energy Info (EERE)

for Others) for this property. Partnering Center within NREL National Center for Photovoltaics Partnership Year 2009 RF Micro Devices is a company located in Greensboro, NC....

433

E-Print Network 3.0 - alcator c-mod radio Sample Search Results  

NLE Websites -- All DOE Office Websites (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...

434

Production of 1-m size uniform plasma by modified magnetron-typed RF discharge with a subsidiary electrode for resonance  

Science Journals Connector (OSTI)

A large-diameter uniform plasma of 1 m in size is produced using a modified magnetron-typed (MMT) RF plasma source at the frequency of 13.56 MHz. The construction and operation of the MMT RF plasma source are very simple and we can place two substrates simultaneously. To achieve an efficient production of high density plasma, a parallel resonance circuit is connected to one of the substrates which acts as a subsidiary RF electrode controlling the plasma parameters. In the case of the resonance the plasma density increases to approximately three times as much as that in case of non-resonance. The plasma density reaches?1×1011/cm3 in Ar at 1 mtorr when the RF input power is 2.8 kW. The MMT RF plasma source provides a plasma with uniformity within several percent over 1 m in diameter in front of the substrate in the low gas pressure regime.

Yuji Urano; Yunlong Li; Keiichi Kanno; Satoru Iizuka; Noriyoshi Sato

1998-01-01T23:59:59.000Z

435

RF/optical shared aperture for high availability wideband communication RF/FSO links  

SciTech Connect

An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

2014-04-29T23:59:59.000Z

436

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

437

Plasma treatment of bulk niobium surface for superconducting rf cavities: Optimization of the experimental conditions on flat samples  

SciTech Connect

Accelerator performance, in particular the average accelerating field and the cavity quality factor, depends on the physical and chemical characteristics of the superconducting radio-frequency (SRF) cavity surface. Plasma based surface modification provides an excellent opportunity to eliminate nonsuperconductive pollutants in the penetration depth region and to remove the mechanically damaged surface layer, which improves the surface roughness. Here we show that the plasma treatment of bulk niobium (Nb) presents an alternative surface preparation method to the commonly used buffered chemical polishing and electropolishing methods. We have optimized the experimental conditions in the microwave glow discharge system and their influence on the Nb removal rate on flat samples. We have achieved an etching rate of 1.7???m/min using only 3% chlorine in the reactive mixture. Combining a fast etching step with a moderate one, we have improved the surface roughness without exposing the sample surface to the environment. We intend to apply the optimized experimental conditions to the preparation of single cell cavities, pursuing the improvement of their rf performance.

M. Raskovic, J. Upadhyay, L. Vuskovic, S. Popovic, A-M. Valente-Feliciano, L. Phillips

2010-11-01T23:59:59.000Z

438

Plasma treatment of bulk niobium surface for superconducting rf cavities: Optimization of the experimental conditions on flat samples  

SciTech Connect

Accelerator performance, in particular the average accelerating field and the cavity quality factor, depends on the physical and chemical characteristics of the superconducting radio-frequency (SRF) cavity surface. Plasma based surface modification provides an excellent opportunity to eliminate nonsuperconductive pollutants in the penetration depth region and to remove the mechanically damaged surface layer, which improves the surface roughness. Here we show that the plasma treatment of bulk niobium (Nb) presents an alternative surface preparation method to the commonly used buffered chemical polishing and electropolishing methods. We have optimized the experimental conditions in the microwave glow discharge system and their influence on the Nb removal rate on flat samples. We have achieved an etching rate of 1.7???m/min? using only 3% chlorine in the reactive mixture. Combining a fast etching step with a moderate one, we have improved the surface roughness without exposing the sample surface to the environment. We intend to apply the optimized experimental conditions to the preparation of single cell cavities, pursuing the improvement of their rf performance.

M. Raskovic, J. Upadhyay, L. Vuskovic, S. Popovic, A-M. Valente-Feliciano, L. Phillips

2010-11-01T23:59:59.000Z

439

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.

440

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.

Note: This page contains sample records for the topic "rf radio frequency" 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

A new microphonics measurement method for superconducting RF cavities  

SciTech Connect

Mechanical vibrations of the superconducting cavity, also known as microphonics, cause shifts in the resonant frequency of the cavity. In addition to requiring additional RF power, these frequency shifts can contribute to errors in the closed loop phase and amplitude regulation. In order to better understand these effects, a new microphonics measurement method was developed, and the method was successfully used to measure microphonics on the half-wave superconducting cavity when it was operated in a production style cryostat. The test cryostat held a single ?=0.1 half-wave cavity which was operated at 162.5 MHz [1] and [2]. It's the first time that the National Instruments PXIe-5641R intermediate frequency transceiver has been used for microphonics measurements in superconducting cavities. The new microphonics measurement method and results will be shown and analyzed in this paper.

Gao,Zheng; He,Yuan; Chang,Wei; Powers, Tom [JLAB; Yue,Wei-ming; Zhu,Zheng-long; Chen,Qi

2014-09-01T23:59:59.000Z

442

National RF Test Facility as a multipurpose development tool  

SciTech Connect

Additions and modifications to the National RF Test Facility design have been made that (1) focus its use for technology development for future large systems in the ion cyclotron range of frequencies (ICRF), (2) expand its applicability to technology development in the electron cyclotron range of frequencies (ECRF) at 60 GHz, (3) provide a facility for ELMO Bumpy Torus (EBT) 60-GHz ring physics studies, and (4) permit engineering studies of steady-state plasma systems, including superconducting magnet performance, vacuum vessel heat flux removal, and microwave protection. The facility will continue to function as a test bed for generic technology developments for ICRF and the lower hybrid range of frequencies (LHRF). The upgraded facility is also suitable for mirror halo physics experiments.

McManamy, T.J.; Becraft, W.R.; Berry, L.A.; Blue, C.W.; Gardner, W.L.; Haselton, H.H.; Hoffman, D.J.; Loring, C.M. Jr.; Moeller, F.A.; Ponte, N.S.

1983-01-01T23:59:59.000Z

443

Cryogenic test of a proof-of-principle superconducting rf-dipole deflecting and crabbing cavity  

Science Journals Connector (OSTI)

Recent applications in need of compact low-frequency deflecting and crabbing cavities have initiated the design and development of new superconducting structures operating at high gradients with low losses. Previously, TM110-type deflecting and crabbing cavities were developed and have also been operated successfully. However, these geometries are not favorable designs for low operating frequencies. The superconducting rf-dipole cavity is the first compact deflecting and crabbing geometry that has demonstrated high gradients and high shunt impedance. Since the fundamental operating mode is the lowest mode and is widely separated from the nearest higher order mode, the rf-dipole design is an attractive geometry for effective damping of the higher order modes in high current applications. A 400 MHz rf-dipole cavity was designed, fabricated, and tested as a proof-of-principle cavity. The cavity achieved high operating gradients, and the multipacting levels were easily processed and did not reoccur.

S. U. De Silva and J. R. Delayen

2013-08-16T23:59:59.000Z

444

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

445

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

446

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

447

Study of AC/RF properties of SRF ingot niobium  

SciTech Connect

In an attempt to correlate the performance of superconducting radiofrequency cavities made of niobium with the superconducting properties, we present the results of the magnetization and ac susceptibility of the niobium used in the superconducting radiofrequency cavity fabrication. The samples were subjected to buffer chemical polishing (BCP) surface and high temperature heat treatments, typically applied to the cavities fabrications. The analysis of the results show the different surface and bulk ac conductivity for the samples subjected to BCP and heat treatment. Furthermore, the RF surface impedance is measured on the sample using a TE011 microwave cavity for a comparison to the low frequency measurements.

Dhakal, Pashupati; Tsindlekht, Menachem I.; Genkin, Valery M.; Ciovati, Gianluigi; Myneni, Ganapati Rao

2013-09-01T23:59:59.000Z

448

Beam dynamics studies for transverse electromagnetic mode type rf deflectors  

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

449

ARIANNA: A radio detector array for cosmic neutrinos on the Ross Ice Shelf  

E-Print Network (OSTI)

ARIANNA (The Antarctic Ross Ice Shelf Antenna Neutrino Array) is a proposed 100 km^3 detector for ultra-high energy (above 10^17 eV) astrophysical neutrinos. It will study the origins of ultra-high energy cosmic rays by searching for the neutrinos produced when these cosmic rays interact with the cosmic microwave background. Over 900 independently operating stations will detect the coherent radio Cherenkov emission produced when astrophysical neutrinos with energy above 10^17 eV interact in the Antarctic Ross Ice Shelf. Each station will use 8 log periodic dipole antennas to look for short RF pulses, with the most important frequencies between 80 MHz and 1 GHz. By measuring the pulse polarization and frequency spectrum, the neutrino arrival direction can be determined. In one year of operation, the full array should observe a clear GZK neutrino signal, with different models predicting between 3 and 51 events, depending on the nuclear composition of the cosmic-rays and on the cosmic evolution of their sources.

Spencer R. Klein; for the ARIANNA Collaboration

2012-11-01T23:59:59.000Z

450

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

451

Note on RF Photo-Cathode Gun  

E-Print Network (OSTI)

E.R. Gray and P.M. Giles, "Photo-cathodes in AcceleratorProceedings Note on RF Photo-Cathode Gun K. -J. Kim August106 LBL-29538 Note on RF Photo-Cathode G un Kwang-Je Kim

Kim, Kwang-Je

2010-01-01T23:59:59.000Z

452

RF SYSTEM FOR THE SNS ACCUMULATOR RING.  

SciTech Connect

During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed.

BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

2001-06-18T23:59:59.000Z

453

Plasma Edge Cooling during rf Heating  

Science Journals Connector (OSTI)

A new approach to prevent the influx of high-Z impurities into the core of a tokamak discharge by using rf power to modify the edge plasma temperature profile is discussed. This concept is based on spectroscopic measurements on PLT (Princeton Large Torus) during ohmic heating and ATC (Adiabatic Toroidal Compressor) during rf heating.

S. Suckewer and R. J. Hawryluk

1978-06-19T23:59:59.000Z

454

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

455

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

456

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

457

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.

458

R&D ERL: Low level RF  

SciTech Connect

A superconducting RF (SRF) Energy Recovery Linac (ERL) is currently under development at the Collider-Accelerator Department (C-AD) at Brookhaven National Laboratory (BNL). The major components from an RF perspective are (a) a 5-cell SRF ERL cavity, (b) an SRF photocathode electron gun, and (c) a drive laser for the photocathode gun. Each of these RF subsystems has its own set of RF performance requirements, as well as common requirements for ensuring correct synchronism between them. A low level RF (LLRF) control system is currently under development, which seeks to leverage both technology and experience gained from the recently commissioned RHIC LLRF system upgrade. This note will review the LLRF system requirements and describe the system to be installed at the ERL.

Smith, K.

2010-01-15T23:59:59.000Z

459

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.

460

Measurement of electron densities by a microwave cavity method in 13.56-MHz RF plasmas of Ar, CF4, C2F6, and CHF3  

Science Journals Connector (OSTI)

Electron densit ies have been determined /or RF plasmas that were generated within a microwave resonant cavity by measuring the difference of the resonance frequencies with and without plasma. Since that metho...

M. Haverlag; G. M. W. Kroesen; T. H. J. Bisschops…

1991-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "rf radio frequency" 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

RF Heating and Current Drive in Magnetically Confined Plasma: a Historical Perspective  

SciTech Connect

The history of high power RF waves injected into magnetically confined plasma for the purposes of heating to fusion relevant temperatures spans nearly five decades. The road to success demanded the development of the theory of wave propagation in high temperature plasma in complex magnetic field geometries, development of antenna structures and transmission lines capable of handling high RF powers, and the development of high power RF (microwave) sources. In the early days, progress was hindered by the lack of good confinement of energetic particles formed by high power RF wave-plasma interactions. For example, in the ion cyclotron resonance frequency regime (ICRF) ions with energies in the multi-100keV, or even MeV range may be formed due to the presence of efficient 'minority species' absorption. Electrons with similar energies can be formed upon the injection of RF waves in the electron cyclotron resonance (ECRH) or lower hybrid range of frequencies (LHRF) because of quasi-linear Landau (cyclotron) interactions between waves and particles. In this paper a summary of four decades of historical evolution of wave heating and current drive results will be given.

Porkolab, Miklos [Massachusetts Institute of Technology, Plasma Science and Fusion Center and Department of Physics, NW 16-288, 167 Albany Street, Cambridge, MA 02139 (United States)

2007-09-28T23:59:59.000Z

462

Underground radio technology saves miners and emergency response personnel  

NLE Websites -- All DOE Office Websites (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

463

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

464

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

465

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.

466

ON THE EVOLUTION OF THE CORES OF RADIO SOURCES AND THEIR EXTENDED RADIO EMISSION  

SciTech Connect

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, res