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Sample records for radio wave scintillations

  1. Radio wave scintillations at equatorial regions

    NASA Technical Reports Server (NTRS)

    Poularikas, A. D.

    1972-01-01

    Radio waves, passing through the atmosphere, experience amplitude and phase fluctuations know as scintillations. A characterization of equatorial scintillation, which has resulted from studies of data recorded primarily in South America and equatorial Africa, is presented. Equatorial scintillation phenomena are complex because they appear to vary with time of day (pre-and postmidnight), season (equinoxes), and magnetic activity. A wider and more systematic geographical coverage is needed for both scientific and engineering purposes; therefore, it is recommended that more observations should be made at earth stations (at low-geomagnetic latitudes) to record equatorial scintillation phenomena.

  2. Scintillation effects on radio wave propagation through solar corona

    NASA Technical Reports Server (NTRS)

    Ho, C. M.; Sue, M. K.; Bedrossian, A.; Sniffin, R. W.

    2002-01-01

    When RF waves pass through the solar corona and solar wind regions close to the Sun, strong scintillation effects appear at their amplitude, frequency and phase, especially in the regions very close to the Sun (less than 4 solar radius).

  3. Radio Sources and Scintillation

    NASA Astrophysics Data System (ADS)

    Rickett, Barney

    2001-10-01

    A review is given of the interplay between studies of compact radio sources and the scattering and scintillations that occur as the signals travel through the irregular refractive index of the interstellar and interplanetary plasmas.

  4. Gravitational wave scintillation by a stellar cluster

    E-print Network

    G. Congedo; F. De Paolis; P. Longo; A. A. Nucita; D. Vetrugno

    2006-10-27

    The diffraction effects on gravitational waves propagating through a stellar cluster are analyzed in the relevant approximation of Fresnel diffraction limit. We find that a gravitational wave scintillation effect - similar to the radio source scintillation effect - comes out naturally, implying that the gravitational wave intensity changes in a characteristic way as the observer moves.

  5. Using Radio Transmitter to Simulate Amplitude Scintillation on Radio Signals

    NASA Astrophysics Data System (ADS)

    Eccles, V.; Ilayian, R.

    2014-12-01

    Rapid fluctuation of radio-frequency signal phase and/or amplitude that is generated as a signal passing through the ionosphere is commonly referred to as ionospheric scintillation. Scintillation occurs as radio frequency signals pass through a field of plasma bubbles or irregularities that can lead to signal power fading, phase cycle slips, poor GPS signals and unusable information. The goal of this research is to use radio wave transmission to simulate scintillation under controlled conditions in order examine the performance of different GPS receivers and their ability to suppress the scintillation. The information gained from the VHF (Very High Frequency) transmitter would serve as a diagnostic tool to better understand the environmental conditions that are causing these irregularities. This system could then be used as a baseline design to be upgraded by NASA engineers to 1.2 GHz - 1.5 GHz for testing out the performance of different GPS receivers. The methodology of VHF testing could be translated to higher frequencies, such as CW (Continuous Wave), which could enhance our understanding of this phenomenon.

  6. Scintillation noise in widefield radio interferometry

    NASA Astrophysics Data System (ADS)

    Vedantham, H. K.; Koopmans, L. V. E.

    2015-10-01

    In this paper, we consider random phase fluctuations imposed during wave propagation through a turbulent plasma (e.g. ionosphere) as a source of additional noise in interferometric visibilities. We derive expressions for visibility variance for the wide field of view case (FOV ˜10°) by computing the statistics of Fresnel diffraction from a stochastic plasma, and provide an intuitive understanding. For typical ionospheric conditions (diffractive scale ˜5-20 km at 150 MHz), we show that the resulting ionospheric `scintillation noise' can be a dominant source of uncertainty at low frequencies (? ? 200 MHz). Consequently, low-frequency widefield radio interferometers must take this source of uncertainty into account in their sensitivity analysis. We also discuss the spatial, temporal, and spectral coherence properties of scintillation noise that determine its magnitude in deep integrations, and influence prospects for its mitigation via calibration or filtering.

  7. Forecasting ionospheric space weather with applications to satellite drag and radio wave communications and scintillation

    NASA Astrophysics Data System (ADS)

    Mannucci, Anthony J.; Tsurutani, Bruce T.; Verkhoglyadova, Olga P.; Meng, Xing; Pi, Xiaoqing; Kuang, Da; Wang, Chunming; Rosen, Gary; Ridley, Aaron; Lynch, Erin; Sharma, Surja; Manchester, Ward B.; van der Holst, Bart

    2015-04-01

    The development of quantitative models that describe physical processes from the solar corona to the Earth’s upper atmosphere opens the possibility of numerical space weather prediction with a lead-time of a few days. Forecasting solar wind-driven variability in the ionosphere and thermosphere poses especially stringent tests of our scientific understanding and modeling capabilities, in particular of coupling processes to regions above and below. We will describe our work with community models to develop upper atmosphere forecasts starting with the solar wind driver. A number of phenomena are relevant, including high latitude energy deposition, its impact on global thermospheric circulation patterns and composition, and global electrodynamics. Improved scientific understanding of this sun to Earth interaction ultimately leads to practical benefits. We will focus on two ways the upper atmosphere affects life on Earth: by changing satellite orbits, and by interfering with long-range radio communications. Challenges in forecasting these impacts will be addressed, with a particular emphasis on the physical bases for the impacts, and how they connect upstream to the sun and the heliosphere.

  8. A decametric wavelength radio telescope for interplanetary scintillation observations

    NASA Technical Reports Server (NTRS)

    Cronyn, W. M.; Shawhan, S. D.

    1975-01-01

    A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.

  9. Radio scintillations observed during atmospheric occultations of Voyager: Internal gravity waves at Titan and magnetic field orientations at Jupiter and Saturn. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Hinson, D. P.

    1983-01-01

    The refractive index of planetary atmospheres at microwave frequencies is discussed. Physical models proposed for the refractive irregularities in the ionosphere and neutral atmosphere serve to characterize the atmospheric scattering structures, and are used subsequently to compute theoretical scintillation spectra for comparison with the Voyager occultation measurements. A technique for systematically analyzing and interpreting the signal fluctuations observed during planetary occultations is presented and applied to process the dual-wavelength data from the Voyager radio occultations by Jupiter, Saturn, and Titan. Results concerning the plasma irregularities in the upper ionospheres of Jupiter and Saturn are reported. The measured orientation of the irregularities is used to infer the magnetic field direction at several locations in the ionospheres of these two planets; the occultation measurements conflict with the predictions of Jovian magnetic field models, but generally confirm current models of Saturn's field. Wave parameters, including the vertical fluxes of energy and momentum, are estimated, and the source of the internal gravity waves discovered in Titan's upper atmosphere is considered.

  10. Interstellar Scintillation of Extragalactic Radio Sources

    NASA Astrophysics Data System (ADS)

    Rickett, Barney

    1998-05-01

    Interstellar scintillation (ISS) causes a Galactic seeing problem for radio astronomy. Thus the flux density from a very compact radio source appears to scintillate on a time scale that ranges from days to minutes depending on the wavelength and Galactic path length. I will review the observed variations from various sources, which are among the most compact cores of active galactic nuclei (AGN). An ISS interpretation of the observed variations yields estimates of the source sizes in the range 0.01 to 10 milliarcsec, often much smaller than the resolution from earth-based VLBI. The recognition of such variations as apparent reduces the implied brightness temperature by a factor as large as one million, compared to the extreme values deduced by interpreting the variations as intrinsic. Some such intraday variable sources also exhibit partially correlated variations in their polarized flux and angle. The changes in interstellar Faradya rotation are too slow to cause such variations by many orders of magnitude. I will report on attempts to model the polarized flux variations as due to independent ISS from polarized components with intrinsic polarization structure in the source at a level of tens of microarcseconds. I will also discuss how Frail et al. (Nature, 389, 261, 1997) used interstellar scintillation to estimate the size of the expanding fireball in the radio afterglow of gamma-ray burst 970508.

  11. Planetary radio waves

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.

    1986-01-01

    Three planets, the earth, Jupiter and Saturn are known to emit nonthermal radio waves which require coherent radiation processes. The characteristic features (frequency spectrum, polarization, occurrence probability, radiation pattern) are discussed. Radiation which is externally controlled by the solar wind is distinguished from internally controlled radiation which only originates from Jupiter. The efficiency of the externally controlled radiation is roughly the same at all three planets (5 x 10 to the -6th) suggesting that similar processes are active there. The maser radiation mechanism for the generation of the radio waves and general requirements for the mechanism which couples the power generator to the region where the radio waves are generated are briefly discussed.

  12. Probing the Cores of Radio Jets through Interstellar Scintillation

    NASA Astrophysics Data System (ADS)

    Rickett, B. J.

    2007-03-01

    Interstellar Scintillation (ISS) has been established as the cause of the random variations in compact radio radio sources on times of a day or less. This interpretation provides quantitative information on the structure of the inner regions of the Radio-Emitting Jets on scales down to 10 ?arcsec, once the distance to the scattering region is known. In turn these imply Doppler factors 5-75, which are on the same order as derived from VLB interferometry.

  13. Radio scintillation of gamma-ray-burst afterglows

    E-print Network

    Jeremy Goodman

    1997-06-09

    Stars twinkle to the eye through atmospheric turbulence, but planets, because of their larger angular size, do not. Similarly, scintillation due to the local interstellar medium will modulate the radio flux of gamma-ray-burst afterglows and may permit indirect measurements of their angular sizes. The amplitude of refractive scintillation is of order ten percent at ten gigahertz unless the source size is much larger than the expected size, of order ten microarcseconds. Diffractive scintillation is marginally possible, depending sensitively on the source size, observing frequency, and scattering measure of the interstellar medium.

  14. The Origin of Radio Scintillation in the Local Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Linsky, Jeffrey L.; Rickett, Barney J.; Redfield, Seth

    2008-03-01

    We study three quasar radio sources (B1257-326, B1519-273, and J1819+385) that show large-amplitude intraday and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens located within a few parsecs of the Sun. We find that the lines of sight to these sources pass through the edges of partially ionized warm interstellar clouds where two or more clouds may interact. From the gas flow vectors of these clouds, we find that the relative radial and transverse velocities of these clouds are large and could generate the turbulence that is responsible for the observed scintillation. For all three sight lines the flow velocities of nearby warm local interstellar clouds are consistent with the fits to the transverse flows of the radio scintillation signals.

  15. Interplanetary scintillation observations with the Cocoa Cross radio telescope

    NASA Technical Reports Server (NTRS)

    Cronyn, W. M.; Shawhan, S. D.; Erskine, F. T.; Huneke, A. H.; Mitchell, D. G.

    1976-01-01

    Physical and electrical parameters for the 34.3-MHz Cocoa Cross radio telescope are given. The telescope is dedicated to the determination of solar-wind characteristics in and out of the ecliptic plane through measurement of electron-density irregularity structure as determined from IPS (interplanetary scintillation) of natural radio sources. The collecting area (72,000 sq m), angular resolution (0.4 deg EW by 0.6 deg NS), and spatial extent (1.3 km EW by 0.8 km NS) make the telescope well suited for measurements of IPS index and frequency scale for hundreds of weak radio sources without serious confusion effects.

  16. Elements of Radio Waves

    E-print Network

    Frank G. Borg; Ismo Hakala; Jukka Määttälä

    2007-12-24

    We present a summary of the basic properties of the radio wave generation, propagation and reception, with a special attention to the gigahertz bandwidth region which is of interest for wireless sensor networks. We also present some measurement results which use the so-called RSSI indicator in order to track how the field strength varies with position and distance of the transceivers. We hope the paper may be useful to anyone who looks for a quick review of the fundamentals of electromagnetic theory with application to antennas.

  17. Outflow structure of the quiet sun corona probed by spacecraft radio scintillations in strong scattering

    SciTech Connect

    Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato; Tokumaru, Munetoshi; Shiota, Daikou; Isobe, Hiroaki; Asai, Ayumi; Miyamoto, Mayu; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander; Yaji, Kentaro; Yamada, Manabu

    2014-06-20

    Radio scintillation observations have been unable to probe flow speeds in the low corona where the scattering of radio waves is exceedingly strong. Here we estimate outflow speeds continuously from the vicinity of the Sun to the outer corona (heliocentric distances of 1.5-20.5 solar radii) by applying the strong scattering theory to radio scintillations for the first time, using the Akatsuki spacecraft as the radio source. Small, nonzero outflow speeds were observed over a wide latitudinal range in the quiet-Sun low corona, suggesting that the supply of plasma from closed loops to the solar wind occurs over an extended area. The existence of power-law density fluctuations down to the scale of 100 m was suggested, which is indicative of well-developed turbulence which can play a key role in heating the corona. At higher altitudes, a rapid acceleration typical of radial open fields is observed, and the temperatures derived from the speed profile show a distinct maximum in the outer corona. This study opened up a possibility of observing detailed flow structures near the Sun from a vast amount of existing interplanetary scintillation data.

  18. Interstellar Scattering and Scintillation as Tools in Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Rickett, B. J.

    1998-05-01

    In recent years Interstellar Scintillation (ISS) has been identified as causing variations in flux density in a variety of radio astronomical observations. Although this ``Galactic seeing'' effect is in some ways a nuisance, ISS is also a valuable tool that provides information on radio source structure at angular scales well beyond the reach of all current interferometers. In addition to ISS, angular and temporal broadening have been measured on many lines of sight in the Galaxy. Such measurements also provide a probe for the fine scale structure in the ionized interstellar plasma. The session will explore the science that can be done using these tools to probe both very compact radio sources and the interstellar plasma. Examples include: ISS provides an explanation of rapid (hours to days - intraday) flux variations at centimeter wavelengths from compact cores of AGNs, reducing the implied brightness temperature by up to six orders of magnitude. ISS has beeen recognised as causing the flux variations from the radio afterglow of the gamma-ray burst observed on May 8 1997, from which a diameter of a few microarcseconds has been estimated for the expanding fireball. A study of the interstellar speckle pattern of the Vela pulsar has achieved nanoarcsecond angular resolution of the pulsar magnetosphere. The Galaxy is permeated by irregular density structures, whose wavenumber spectrum is like a turbulent fluid over at least six and as many as ten orders of magnitude in length scale. However, the local strength of turbulence is itself non-uniform, with localized enhancemnents by more than six orders of magnitude, whose physical origin is still obscure.

  19. Interstellar Scintillation Observations of 146 Extragalactic Radio Sources

    NASA Astrophysics Data System (ADS)

    Rickett, Barney J.; Lazio, T. J. W.; Ghigo, Frank D.

    2006-08-01

    From 1979 to 1996 the Green Bank Interferometer was used by the Naval Research Laboratory to monitor the flux density from 146 compact radio sources at frequencies near 2 and 8 GHz. We filter the ``light curves'' to separate intrinsic variations on times of a year or more from more rapid interstellar scintillation (ISS) on times of 5-50 days. Whereas the intrinsic variation at 2 GHz is similar to that at 8 GHz (although diminished in amplitude), the ISS variation is much stronger at 2 than at 8 GHz. We characterize the ISS variation by an rms amplitude and a timescale and examine the statistics of these parameters for the 121 sources with significant ISS at 2 GHz. We model the scintillations using the NE2001 Galactic electron model assuming the sources are brightness-limited. We find the observed rms amplitude to be in general agreement with the model, provided that the compact components of the sources have about 50% of their flux density in a component with maximum brightness temperatures 1011-1012 K. Thus, our results are consistent with centimeter-wavelength VLBI studies of compact active galactic nuclei, in that the maximum brightness temperatures found are consistent with the inverse synchrotron limit at 3×1011 K, boosted in jet configurations by Doppler factors up to about 20. The average of the observed 2 GHz ISS timescales is in reasonable agreement with the model at Galactic latitudes above about 10°. At lower latitudes the observed timescales are too fast, suggesting that the transverse velocity increases beyond about 1 kpc, which may be due to differential Galactic rotation.

  20. Scintillation of Radio Sources: The Signature of a Caustic

    NASA Astrophysics Data System (ADS)

    Watson, P. G.; Melrose, D. B.

    2006-08-01

    The role of caustics in the scintillation of radio sources due to thin-screen scattering is explored. The classical stationary phase treatment of this type of scattering implies singular behavior at the caustics. Physically, this singularity is resolved by diffractive effects, and a smooth but highly peaked intensity distribution is expected, analogous to what we observe in geometrical optics. However, in a companion paper we showed that the intensity amplification near a caustic can be very mild and is typically swamped by a rapidly oscillating diffractive interference pattern. In this paper we introduce a modified stationary phase method that employs an Airy function approximation near caustics. This modified method provides an accurate estimate of the intensity near the caustic and allows us to show that significant intensity enhancement is only expected to develop for extremely strong scattering screens. In this limit the behavior of the intensity near the caustic depends on only a small number of bulk properties of the scattering screen. As such, not only does it provide a clear signature for when a caustic has been crossed, it also may be used to yield important properties of the scattering medium.

  1. Radio Wave Emission from the Outer Planets

    E-print Network

    Meyer-Vernet, Nicole

    Radio Wave Emission from the Outer Planets P. Zarka LESIA, Observatoire de Paris, Meudon #12;All outer planets) produce intense nonthermal radio emissions potentially interesting remote sensing tool of magnetospheric plasma(s) we can "see" magnetospheres directly, but do we understand what we see ? #12;"Radio

  2. Solar wind interaction with the ionosphere of Venus inferred from radio scintillation measurements

    SciTech Connect

    Woo, R.; Sjogren, W.L.; Kliore, A.J. ); Luhmann, J.G. ); Brace, L.H. )

    1989-02-01

    This paper presents the first S-band (2.3 GHz) radio scintillations observed in the ionosphere of Venus and discovered when the Pioneer Venus Orbiter spacecraft traversed the ionosphere of Venus. In situ plasma measurements as well as propagation calculations confirm that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. While these topside plasma irregularities have not been studied before, simultaneous magnetic field measurements presented here reveal that they are associated with the penetration of large-scale magnetic fields in the ionosphere. Previous studies based on extensive magnetic field measurements have shown that the presence of large-scale magnetic fields occurs in the subsolar region when the solar wind dynamic pressure exceeds the ionospheric plasma pressure. As with the large-scale magnetic fields, the disturbed plasma and resulting scintillations are therefore a manifestation of high-dynamic solar wind interaction with the ionosphere. Since the scintillations only occur in the subsolar region of Venus, the global morphology of ionospheric scintillations at Venus is different from that of the terrestrial ionosphere, where scintillations are observed in both polar and equatorial regions, with peaks occurring during nighttime. This difference apparently stems from the fact that Venus is not a magnetic planet. The authors also demonstrate that the disturbed plasma produced by the high-dynamic solar wind interaction can be remotely sensed by scintillations during radio occultation measurements, that is, when the spacecraft is outside the ionosphere.

  3. Radio Scintillation Due to Discontinuities in the Interstellar Plasma Density

    NASA Astrophysics Data System (ADS)

    Lambert, H.; Rickett, B.

    1996-12-01

    We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral index of beta = 4 corresponding to a medium with abrupt changes in its density. An ``outer scale'' is included in the model representing the range over which the density of the medium remains uniform. Such a spectrum could be used to model plasma shock fronts in supernova remnants. We investigate and develop equations for pulse broadening, decorrelation bandwidth of diffractive scintillations, and the refractive scintillation index and compare our results with pulsar measurements. We consider both a medium concentrated in a thin layer and an extended irregular medium. We conclude that the beta = 4 model gives satisfactory agreement for many diffractive measurements, but that for the refractive scintillation index, it gives less satisfactory agreement than does the Kolmogorov turbulence spectrum. We propose to investigate a composite spectrum, featuring a uniform background turbulence with randomly distributed discrete objects, as modelled by the beta = 4 spectrum.

  4. Antenna Construction and Propagation of Radio Waves.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on antenna construction and propagation of radio waves is designed to provide communicators with instructions in the selection and/or construction of the proper antenna(s) for use with current field radio equipment. Introductory materials include…

  5. Electro Magnetic (EM) Uses Radio Waves

    E-print Network

    Naik, Naren

    #12;RADAR Electro Magnetic (EM) SENSOR Uses Radio Waves Used for Detection of Objects Finding as a Motivation for Learning and Understanding DSP Radar concepts can be used in ROBOT Radar, SONAR ,Ultrasonic ranging etc #12;INTRODUCTION TO RADAR RADAR = Radio Detection and Ranging · Detects targets by receipt

  6. Radio Scintillation due to Discontinuities in the Interstellar Plasma Density

    NASA Astrophysics Data System (ADS)

    Lambert, H. C.; Rickett, B. J.

    2000-03-01

    We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial-density spectrum with a spectral exponent of ?=4 corresponding to a medium with abrupt changes in its density. An ``outer scale'' is included in the model that represents the typical scale over which the density of the medium remains uniform. Such a spectrum could be used to model plasma shock fronts in supernova remnants or other plasma discontinuities. We investigate and develop equations for the decorrelation bandwidth of diffractive scintillations and the refractive scintillation index and compare our results with pulsar measurements. We consider both a medium concentrated in a thin layer and an extended irregular medium. We conclude that the ?=4 model gives satisfactory agreement for many diffractive measurements, in particular the VLBI measurements of the structure function exponent between 5/3 and 2. However, it gives less satisfactory agreement for the refractive scintillation index than does the Kolmogorov turbulence spectrum. The comparison suggests that the medium consists of a pervasive background distribution of turbulence embedded with randomly placed discrete plasma structures such as shocks or H II regions. This can be modeled by a composite spectrum following the Kolmogorov form at high wavenumbers and steepening at lower wavenumbers corresponding to the typical (inverse) size of the discrete structures. Such a model can also explain the extreme scattering events. However, lines of sight through the enhanced scattering prevalent at low Galactic latitudes are accurately described by the Kolmogorov spectrum in an extended medium and do not appear to have a similar low-wavenumber steepening.

  7. Speckles in interstellar radio-wave scattering

    NASA Technical Reports Server (NTRS)

    Desai, K. M.; Gwinn, C. R.; Reynolds, J.; King, E. A.; Jauncey, D.; Nicholson, G.; Flanagan, C.; Preston, R. A.; Jones, D. L.

    1991-01-01

    Observations of speckles in the scattering disk of the Vela pulsar are presented and speckle techniques for studying and circumventing scattering of radio waves by the turbulent interstellar plasma are discussed. The speckle pattern contains, in a hologrammatic fashion, complete information on the structure of the radio source as well as the distribution of the scattering material. Speckle observations of interstellar scattering of radio waves are difficult because of their characteristically short timescales and narrow bandwidths. Here, first observations are presented, taken at 13 cm wavelength with elements of the SHEVE VLBI network, of speckles in interstellar scattering.

  8. Wave-wave interactions in solar type III radio bursts

    NASA Astrophysics Data System (ADS)

    Thejappa, G.; MacDowall, R. J.

    2014-02-01

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

  9. Wave-wave interactions in solar type III radio bursts

    SciTech Connect

    Thejappa, G.; MacDowall, R. J.

    2014-02-11

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

  10. Information Content in Radio Waves: Student Investigations in Radio Science

    NASA Astrophysics Data System (ADS)

    Jacobs, K.; Scaduto, T.

    2013-12-01

    We describe an inquiry-based instructional unit on information content in radio waves, created in the summer of 2013 as part of a MIT Haystack Observatory (Westford, MA) NSF Research Experiences for Teachers (RET) program. This topic is current and highly relevant, addressing science and technical aspects from radio astronomy, geodesy, and atmospheric research areas as well as Next Generation Science Standards (NGSS). Projects and activities range from simple classroom demonstrations and group investigations, to long term research projects incorporating data acquisition from both student-built instrumentation as well as online databases. Each of the core lessons is applied to one of the primary research centers at Haystack through an inquiry project that builds on previously developed units through the MIT Haystack RET program. In radio astronomy, students investigate the application of a simple and inexpensive software defined radio chip (RTL-SDR) for use in systems implementing a small and very small radio telescope (SRT and VSRT). Both of these systems allow students to explore fundamental principles of radio waves and interferometry as applied to radio astronomy. In ionospheric research, students track solar storms from the initial coronal mass ejection (using Solar Dynamics Observatory images) to the resulting variability in total electron density concentrations using data from the community standard Madrigal distributed database system maintained by MIT Haystack. Finally, students get to explore very long-baseline interferometry as it is used in geodetic studies by measuring crustal plate displacements over time. Alignment to NextGen standards is provided for each lesson and activity with emphasis on HS-PS4 'Waves and Their Applications in Technologies for Information Transfer'.

  11. Technologies for DWDM Millimetre-Wave Fibre-Radio Networks

    E-print Network

    Bakaul, Masuduzzaman

    Technologies for DWDM Millimetre- Wave Fibre-Radio Networks Masuduzzaman Bakaul BSc. Eng. (EE. The millimetre-wave (mm-wave) fibre-radio system with its inherent advantages of large bandwidth characteristics services and applications. At mm-wave frequencies, propagation effects through the air limit the radio cell

  12. Antipodal propagation of decameter radio waves

    NASA Astrophysics Data System (ADS)

    Bryantsev, V. F.

    2013-02-01

    We consider specific features of the antipodal propagation of decameter radio waves based on long-range radio-path measurement data. The measurements were carried out at frequencies of 10 and 15 MHz onboard a research vessel when it crossed the antipodal region of the RID universal-time station located near the city of Irkutsk. Reduced multipath-effect band, increased level of received signals in the antipodal region, and details of diurnal variations of the signal amplitude are discussed.

  13. CONSTRAINING THE VELA PULSAR'S RADIO EMISSION REGION USING NYQUIST-LIMITED SCINTILLATION STATISTICS

    SciTech Connect

    Johnson, M. D.; Gwinn, C. R.; Demorest, P. E-mail: cgwinn@physics.ucsb.edu

    2012-10-10

    Using a novel technique, we achieve {approx}100 picoarcsec resolution and set an upper bound of less than 4 km for the characteristic size of the Vela pulsar's emission region. Specifically, we analyze flux-density statistics of the Vela pulsar at 760 MHz. Because the pulsar exhibits strong diffractive scintillation, these statistics convey information about the spatial extent of the radio emission region. We measure both a characteristic size of the emission region and the emission sizes for individual pulses. Our results imply that the radio emission altitude for the Vela pulsar at this frequency is less than 340 km.

  14. Gravitational Wave Emission from Galactic Radio Pulsars

    E-print Network

    J. A. de Freitas Pacheco; J. E. Horvath

    1997-04-15

    We consider in this work continuous gravitational wave (GW) emission from non-axisymmetric radio pulsars. We treat in some detail the observational issues related to the known radio pulsar sample with the aim of unveiling the actual number of sources contributing to GW, which are likely to be the main contributors of GWs. It is shown that the operation of spheroidal GW detectors and full-size interferometers could detect this component of the radiation or impose useful limits on the effective oblateness of young radio pulsars.

  15. The Unified Radio and Plasma wave investigation

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Bougeret, J. L.; Caldwell, J.; Canu, P.; De Conchy, Y.; Cornilleau-Wehrlin, N.; Desch, M. D.; Fainberg, J.; Goetz, K.; Goldstein, M. L.

    1992-01-01

    The scientific objectives of the Ulysses Unified Radio and Plasma wave (URAP) experiment are twofold: (1) the determination of the direction, angular size, and polarization of radio sources for remote sensing of the heliosphere and the Jovian magnetosphere and (2) the detailed study of local wave phenomena, which determine the transport coefficients of the ambient plasma. A brief discussion of the scientific goals of the experiment is followed by a comprehensive description of the instrument. The URAP sensors consist of a 72.5 m electric field antenna in the spin plane, a 7.5-m electric field monopole along the spin axis of a pair of orthogonal search coil magnetic antennas. The various receivers, designed to encompass specific needs of the investigation, cover the frequency range from dc to 1 MHz. A relaxation sounder provides very accurate electron density measurements. Radio and plasma wave observations are shown to demonstrate the capabilities and limitations of the URAP instruments: radio observations include solar bursts, auroral kilometric radiation, and Jovian bursts; plasma waves include Langmuir waves, ion acousticlike noise, and whistlers.

  16. Radio Wave Propagation in Potato Fields John Thelen

    E-print Network

    Langendoen, Koen

    Radio Wave Propagation in Potato Fields John Thelen Wageningen University Email: John has an important effect on the propagation of radio waves. The influence of the growth stage from 23 m to 10 m. Another important result is that radio waves propagate better in conditions

  17. Detection Of Cosmic Rays Air Showers Using Radio Antenna Arrays And Scintillation Counters

    NASA Astrophysics Data System (ADS)

    Papageorgiou, K.; Tzamarias, S.; Gkialas, I.; Tsirigotis, A.; Bourlis, G.; Manthos, I.; Avgitas, G.

    2014-06-01

    In this progress report we describe a test bench developed in order to evaluate the performance of radio antennas and other gaseous detectors in detecting air showers initiating by cosmic rays. This test bench is based on an array of HELYCON scintillation counters and is used to operate a digital radio telescope. The results of this research and development activity will be applied in developing a sea top calibration array of an underwater neutrino telescope. We also describe the performance of a single HELYCON station in detecting and reconstructing showers as well as on the pilot operation of a single low frequency radio antenna in order to develop techniques to suppress the contribution of the anthropogenic RF background originated from human activities.

  18. Effect of blowing snow and ground blizzards on millimeter wave scintillation spectra

    NASA Astrophysics Data System (ADS)

    Sarma, A. D.; Hill, R. J.

    1991-09-01

    We describe the effect of ground blizzards and blowing snow on millimeter wave scintillation spectra at 116 and 230 GHz. During snowstorms, multipath propagation can occur for various reasons. Whatever the reason for the multipath, it will affect the scintillation spectrum. Enhancement of the scintillation spectrum is observed at both low and high temporal frequencies. In some cases, two additional corner frequencies are evident at the high-frequency end of the scintillation spectrum. The method of obtaining the cross-path wind component fails when the wind is nearly parallel to the propagation path.

  19. HF Radio Wave Production of Artificial Ionospheres

    NASA Astrophysics Data System (ADS)

    Carlson, Herbert

    In 1993 it was predicted that artificial ionospheres would be produced by high power HF radio waves, once HF transmitters approached a GWatt ERP. When that threshold was very recently achieved, such production was indeed detected and published at two high latitude high power HF facilities. Here we review: the first-principles logic behind that prediction, which aspects of such production are critically dependent on magnetic latitude, and which aspects of such production depend only on physical parameters independent of latitude. These distinctions follow directly from decomposition of the problem of ionization production into its components of: radio-wave propagation, wave-particle interactions, electron transport, and quantitative elastic/inelastic cross-sections. We outline this analysis to show that, within the context of early observations, the production of ionization is inevitable, and only a question of competing instability thresholds, and scale of ionization production. This illustrates complimentary aeronomy and plasma physics to advance understanding of both.

  20. Polycrystalline para-terphenyl scintillator adopted in a $\\beta^-$ detecting probe for radio-guided surgery

    E-print Network

    Camillocci, Elena Solfaroli; Bocci, Valerio; Collamati, Francesco; De Lucia, Erika; Faccini, Riccardo; Marafini, Michela; Mattei, Ilaria; Morganti, Silvio; Paramatti, Riccardo; Patera, Vincenzo; Pinci, Davide; Recchia, Luigi; Russomando, Andrea; Sarti, Alessio; Sciubba, Adalberto; Senzacqua, Martina; Voena, Cecilia

    2015-01-01

    A radio-guided surgery technique exploiting $\\beta^-$ emitters is under development. It aims at a higher target-to-background activity ratio implying both a smaller radiopharmaceutical activity and the possibility of extending the technique to cases with a large uptake of surrounding healthy organs. Such technique requires a dedicated intraoperative probe detecting $\\beta^-$ radiation. A first prototype has been developed relying on the low density and high light yield of the diphenylbutadiene doped para-therphenyl organic scintillator. The scintillation light produced in a cylindrical crystal, 5 mm in diameter and 3 mm in height, is guided to a photo-multiplier tube by optical fibres. The custom readout electronics is designed to optimize its usage in terms of feedback to the surgeon, portability and remote monitoring of the signal. Tests show that with a radiotracer activity comparable to those administered for diagnostic purposes the developed probe can detect a 0.1 ml cancerous residual of meningioma in a...

  1. Polycrystalline para-terphenyl scintillator adopted in a ?- detecting probe for radio-guided surgery

    NASA Astrophysics Data System (ADS)

    Solfaroli Camillocci, E.; Bellini, F.; Bocci, V.; Collamati, F.; De Lucia, E.; Faccini, R.; Marafini, M.; Mattei, I.; Morganti, S.; Paramatti, R.; Patera, V.; Pinci, D.; Recchia, L.; Russomando, A.; Sarti, A.; Sciubba, A.; Senzacqua, M.; Voena, C.

    2015-06-01

    A radio-guided surgery technique exploiting ?- emitters is under development. It aims at a higher target-to-background activity ratio implying both a smaller radiopharmaceutical activity and the possibility of extending the technique to cases with a large uptake of surrounding healthy organs. Such technique requires a dedicated intraoperative probe detecting ?- radiation. A first prototype has been developed relying on the low density and high light yield of the diphenylbutadiene doped para-therphenyl organic scintillator. The scintillation light produced in a cylindrical crystal, 5 mm in diameter and 3 mm in height, is guided to a photo-multiplier tube by optical fibres. The custom readout electronics is designed to optimize its usage in terms of feedback to the surgeon, portability and remote monitoring of the signal. Tests show that with a radiotracer activity comparable to those administered for diagnostic purposes the developed probe can detect a 0.1 ml cancerous residual of meningioma in a few seconds.

  2. Radio-wave propagation through a medium containing electron-density fluctuations described by an anisotropic Goldreich-Sridhar spectrum

    E-print Network

    B. D. G. Chandran; D. C. Backer

    2002-02-13

    We study the propagation of radio waves through a medium possessing density fluctuations that are elongated along the ambient magnetic field and described by an anisotropic Goldreich-Sridhar power spectrum. We derive general formulas for the wave phase structure function, visibility, angular broadening, diffraction-pattern length scales, and scintillation time scale for arbitrary distributions of turbulence along the line of sight, and specialize these formulas to idealized cases.

  3. Coronal Radio Sounding Experiments with Mars Express: Scintillation Spectra during Low Solar Activity

    SciTech Connect

    Efimov, A. I.; Lukanina, L. A.; Samoznaev, L. N.; Rudash, V. K.; Chashei, I. V.; Bird, M. K.; Paetzold, M.; Tellmann, S.

    2010-03-25

    Coronal radio sounding observations were carried out with the radio science experiment MaRS on the ESA spacecraft Mars Express during the period from 25 August to 22 October 2004. Differential frequency and log-amplitude fluctuations of the dual-frequency signals were recorded during a period of low solar activity. The data are applicable to low heliographic latitudes, i.e. to slow solar wind. The mean frequency fluctuation and power law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The radial dependence of the frequency fluctuation spectral index alpha reflects the previously documented flattening of the scintillation power spectra in the solar wind acceleration region. Temporal spectra of S-band and X-band normalized log-amplitude fluctuations were investigated over the range of fluctuation frequencies 0.01 Hzscintillation data. Evidence for a weak increase in the fractional electron density turbulence level is obtained in the range 10-40 solar radii.

  4. Observations of Interplanetary Scintillation (IPS) Using the Mexican Array Radio Telescope (MEXART)

    NASA Astrophysics Data System (ADS)

    Mejia-Ambriz, J. C.; Villanueva-Hernandez, P.; Gonzalez-Esparza, J. A.; Aguilar-Rodriguez, E.; Jeyakumar, S.

    2010-08-01

    The Mexican Array Radio Telescope (MEXART) consists of a 64×64 (4096) full-wavelength dipole antenna array, operating at 140 MHz, with a bandwidth of 2 MHz, occupying about 9660 square meters (69 m × 140 m) ( http://www.mexart.unam.mx ). This is a dedicated radio array for Interplanetary Scintillation (IPS) observations located at latitude 19°48'N, longitude 101°41'W. We characterize the performance of the system. We report the first IPS observations with the instrument, employing a Butler Matrix (BM) of 16×16 ports, fed by 16 east - west lines of 64 dipoles (1/4 of the total array). The BM displays a radiation pattern of 16 beams at different declinations (from -48, to +88 degrees). We present a list of 19 strong IPS radio sources (having at least 3 ? in power gain) detected by the instrument. We report the power spectral analysis procedure of the intensity fluctuations. The operation of MEXART will allow us a better coverage of solar wind disturbances, complementing the data provided by the other, previously built, instruments.

  5. Fossil Radio Plasma in Cluster Merger Shock Waves

    E-print Network

    Torsten A. Ensslin; Marcus Brueggen

    2001-04-06

    In several merging clusters of galaxies so-called cluster radio relics have been observed. These are extended radio sources which do not seem to be associated with any radio galaxy. Two competing physical mechanisms to accelerate the radio emitting electrons have been proposed: (i) diffusive shock acceleration and (ii) adiabatic compression of fossil radio plasma by merger shock waves. Here the second scenario is investigated. We present detailed 3-dimensional magneto-hydrodynamical simulations of the passage of a radio plasma cocoon through a shock wave. Taking into account synchrotron, inverse Compton and adiabatic energy losses and gains we evolved the relativistic electron population to produce synthetic radio maps in Stokes I-, Q-, and U-polarisation. In the synthetic radio maps the electric polarisation vectors are mostly perpendicular to the filamentary radio structures.

  6. Radio wave emissions due to gravitational radiation

    E-print Network

    Mattias Marklund; Gert Brodin; Peter Dunsby

    2000-02-29

    We consider the interaction of a weak gravitational wave with electromagnetic fields in a thin plasma on a Minkowski background spacetime using the 1+3 orthonormal frame formalism. Because gravitational and electromagnetic waves satisfy the same dispersion relation, electromagnetic waves can be effectively generated as a result of this interaction. In the case of the interaction with a static magnetic field, the amplitude of the electromagnetic waves depends on the size of the excitation region in which the magnetic field is contained. It is argued that due to the presence of a plasma this process can also lead to the generation of higher harmonics of the original mode. Estimates are given for this effect in the case of a binary pulsar and a cold electron plasma. It is found that the emmited radiation will lie in the radio frequency band. We also speculate on the possible relevance of this process on situations in cosmology, in particular whether this could be used to constrain primordial magnetic fields.

  7. Radio-wave propagation for space communications systems

    NASA Technical Reports Server (NTRS)

    Ippolito, L. J.

    1981-01-01

    The most recent information on the effects of Earth's atmosphere on space communications systems is reviewed. The design and reliable operation of satellite systems that provide the many applications in space which rely on the transmission of radio waves for communications and scientific purposes are dependent on the propagation characteristics of the transmission path. The presence of atmospheric gases, clouds, fog, precipitation, and turbulence causes uncontrolled variations in the signal characteristics. These variations can result in a reduction of the quality and reliability of the transmitted information. Models and other techniques are used in the prediction of atmospheric effects as influenced by frequency, geography, elevation angle, and type of transmission. Recent data on performance characteristics obtained from direct measurements on satellite links operating to above 30 GHz have been reviewed. Particular emphasis has been placed on the effects of precipitation on the Earth/space path, including rain attenuation, and ice particle depolarization. Other factors are sky noise, antenna gain degradation, scintillations, and bandwidth coherence. Each of the various propagation factors has an effect on design criteria for communications systems. These criteria include link reliability, power margins, noise contribution, modulation and polarization factors, channel cross talk, error rate, and bandwidth limitations.

  8. Effects of D region ionization on radio wave propagation

    NASA Technical Reports Server (NTRS)

    Larsen, T. R.

    1979-01-01

    The effects of anomalous D region ionization upon radio wave propagation are described for the main types of disturbances: sudden ionospheric disturbances, relativistic electron events, magnetic storms, auroral disturbances, polar cap events, and stratospheric warmings. Examples of radio wave characteristics for such conditions are given for the frequencies between the extremely low (3-3000 Hz) and high (3-30 MHz) frequency domains. Statistics on the disturbance effects and radio wave data are given in order to contribute towards the evaluation of possibilities for predicting the radio effects.

  9. Actual Reflectometer on Fusion Experiment Emit radio frequency waves,

    E-print Network

    Budny, Robert

    Actual Reflectometer on Fusion Experiment Emit radio frequency waves, measure reflected waves waves downloaded from URL. Added interactive graphics & visualization without changing existing Fortran 1019 1 keV 1 T Visualize Input Plasma Cross Sections Wave Reflection Layer (Cut-off Location) Compute

  10. Radio wave scattering in the outer heliosphere

    NASA Astrophysics Data System (ADS)

    Armstrong, J. W.; Coles, W. A.; Rickett, B. J.

    2000-03-01

    The Voyager 1 and 2 plasma wave instruments have observed low-frequency (1.5-4 kHz) radio waves apparently generated near the heliopause. The waves are found in two distinct bands. Power at the lower frequencies centered on 1.78 kHz shows no modulation when the spacecraft is rolled about the Earth-spacecraft line, indicating that the radiation is isotropic. Power in the higher band centered on 3.11 kHz shows roll modulation as high as 60%, indicating that the source of the radiation is quite compact, subtending an angle <1 rad at the spacecraft. Simple estimates of the scattering of 3.11 kHz radiation from electron density fluctuations indicate that, if the radiation had originated from the distance of the heliopause, the scattering would be so large that no roll modulation should be observed. Here we show that these earlier scattering estimates were too high because they ignored the latitude variation of scattering and the inner scale of the electron density fluctuation spectrum. With these two effects properly included, the expected scattering is consistent with the observations and the postulate that the radiation originates from near the nose of the heliosphere.

  11. Magnetospheric radio and plasma wave research - 1987-1990

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    1991-01-01

    This review covers research performed in the area of magnetospheric plasma waves and wave-particle interactions as well as magnetospheric radio emissions. The report focuses on the near-completion of the discovery phase of radio and plasma wave phenomena in the planetary magnetospheres with the successful completion of the Voyager 2 encounters of Neptune and Uranus. Consideration is given to the advances made in detailed studies and theoretical investigations of radio and plasma wave phenomena in the terrestrial magnetosphere or in magnetospheric plasmas in general.

  12. Gravitation Wave Emission from Radio Pulsars Revisited

    E-print Network

    T. Regimbau; J. A. de Freitas Pacheco

    2000-05-02

    We report a new pulsar population synthesis based on Monte Carlo techniques, aiming to estimate the contribution of galactic radio pulsars to the continuous gravitational wave emission. Assuming that the rotation periods of pulsars at birth have a Gaussian distribution, we find that the average initial period is 290 ms. The number of objects with periods equal to or less than 0.4 s, and therefore capable of being detected by an interferometric gravitational antenna like VIRGO, is of the order of 5100-7800. With integration times lasting between 2 and 3 yr, our simulations suggest that about two detections should be possible, if the mean equatorial ellipticity of the pulsars is $\\epsilon$ =10$^{-6}$. A mean ellipticity an order of magnitude higher increases the expected number of detections to 12-18, whereas for $\\epsilon < 10^{-6}$, no detections are expected

  13. Drift Wave Model of Rotating Radio Transients

    E-print Network

    D. Lomiashvili; G. Machabeli; I. Malov

    2007-09-13

    During the last few years there were discovered and deeply examined several transient neutron stars (Rotating Radio Transients). It is already well accepted that these objects are rotating neutron stars. But their extraordinary features (burst-like behavior) made necessary revision of well accepted models of pulsar interior structure. Nowadays most popular model for RRATs is precessing pulsar model, which is the subject of big discussion. We assume that these objects are pulsars with specific spin parameters. An important feature of our model, naturally explaining most of the properties of these neutron stars, is presence of very low frequency, nearly transverse drift waves propagating across the magnetic field and encircling the open field lines region of the pulsar magnetosphere.

  14. Type III radio bursts: STEREO/WAVES observations

    NASA Astrophysics Data System (ADS)

    Krupar, Vratislav; Maksimovic, Milan; Santolik, Ondrej; Cecconi, Baptiste

    2010-05-01

    Type III radio bursts are the most intense interplanetary radio waves observed in the solar wind. Electrostatic Langmuir waves (produced by field-aligned beams of fast electrons connected with coronal mass ejections and/or solar flares) are triggers of the type III radio bursts. The two STEREO spacecraft provide us with unique stereoscopic observations of the Sun. The S/WAVES instruments (the HFR receivers) measure all components of the electric field in a frequency range from 125 kHz up to 1975 kHz. It allows us to investigate directions of the wave vectors and estimate apparent source sizes as well. In this paper the Singular Value Decomposition method has been used as an effective tool for multi-component wave analysis. A statistical study (based on 80 events) of goniopolarimetric properties of the type III radio bursts will be presented. We have investigated a spatial distribution of their sources. We have also studied the apparent source sizes.

  15. Making Waves: Pirate Radio and Popular Music.

    ERIC Educational Resources Information Center

    Jones, Steve

    The history of pirate radio--radio broadcasts offered by unlicensed broadcasters as alternatives to licensed, commercial radio programming--is difficult to trace, both in America and the United Kingdom (UK) since mention of pirate broadcasts of a less-then-thrilling nature are rarely found. Also, until 1927, the U.S. government did not formally…

  16. Plasma and radio waves from Neptune: Source mechamisms and propagation

    NASA Technical Reports Server (NTRS)

    Menietti, J. Douglas

    1994-01-01

    The purpose of this project was to conduct a comprehensive investigation of the radio wave emission observed by the planetary radio astronomy (PRA) instrument on board Voyager 2 as it flew by Neptune. The study has included data analysis, theoretical and numerical calculations, and ray tracing to determine the possible source mechanisms and locations of the radiation, including the narrowband bursty and smooth components of the Neptune radio emission.

  17. Ulysses Radio and Plasma Wave Observations at High Southern Heliographic Latitudes

    E-print Network

    California at Berkeley, University of

    Ulysses Radio and Plasma Wave Observations at High Southern Heliographic Latitudes R. G. Stone, R-Frey, R. Manning, M. J. Reiner, J. L. Steinberg, G. Thejappa Ulysses spacecraft radio and plasma wave wind. Radio and plasma wave observations, such as those made by the Unified Radio and Plasma Wave

  18. The ISPM unified radio and plasma wave experiment

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Caldwell, J.; Deconchy, Y.; Deschanciaux, C.; Ebbett, R.; Epstein, G.; Groetz, K.; Harvey, C. C.; Hoang, S.; Howard, R.

    1983-01-01

    Hardware for the International Solar Polar Mission (ISPM) Unified Radio and Plasma (URAP) wave experiment is presented. The URAP determines direction and polarization of distant radio sources for remote sensing of the heliosphere, and studies local wave phenomena which determine the transport coefficients of the ambient plasma. Electric and magnetic field antennas and preamplifiers; the electromagnetic compatibility plan and grounding; radio astronomy and plasma frequency receivers; a fast Fourier transformation data processing unit waveform analyzer; dc voltage measurements; a fast envelope sampler for the solar wind, and plasmas near Jupiter; a sounder; and a power converter are described.

  19. Plasma and radio waves from Neptune: Source mechanisms and propagation

    NASA Technical Reports Server (NTRS)

    Wong, H. K.

    1994-01-01

    This report summarizes results obtained through the support of NASA Grant NAGW-2412. The objective of this project is to conduct a comprehensive investigation of the radio wave emission observed by the planetary radio astronomy (PRA) instrument on board Voyager 2 as if flew by Neptune. This study has included data analysis, theoretical and numerical calculations, ray tracing, and modeling to determine the possible source mechanism(s) and locations of the Neptune radio emissions. We have completed four papers, which are included in the appendix. The paper 'Modeling of Whistler Ray Paths in the Magnetosphere of Neptune' investigated the propagation and dispersion of lighting-generated whistler in the magnetosphere of Neptune by using three dimensional ray tracing. The two papers 'Numerical Simulations of Bursty Radio Emissions from Planetary Magnetospheres' and 'Numerical Simulations of Bursty Planetary Radio Emissions' employed numerical simulations to investigate an alternate source mechanism of bursty radio emissions in addition to the cyclotron maser instability. We have also studied the possible generation of Z and whistler mode waves by the temperature anisotropic beam instability and the result was published in 'Electron Cyclotron Wave Generation by Relativistic Electrons.' Besides the aforementioned studies, we have also collaborated with members of the PRA team to investigate various aspects of the radio wave data. Two papers have been submitted for publication and the abstracts of these papers are also listed in the appendix.

  20. A New Method for Studying the Solar Wind Using Radio Scintillations (IPS)

    NASA Astrophysics Data System (ADS)

    Coles, W. A.; Harmon, J. K.; Rickett, B. J.; Venkataraman, A.

    2003-12-01

    Intensity scintillations (IPS) have been used to measure the velocity and the micro-structure of the solar wind for many years. Observations with a single antenna are simple and easily arranged, but they provide only one-dimensional information on the microstructure and they are subject to bias if the microstructure is anisotropic or the scattering becomes ``strong.'' Observations with two or more antennas provide a two-dimensional measure of the microstructure; a vector velocity; and they are more robust in the onset of strong scattering. However there are few suitable arrays and they are difficult to schedule. In either case a reliable estimate requires that many time scales be observed - typically about 10 minutes of observation. Here we report a robust new method which requires only one antenna, but is not sensitive to either anisotropic structure or strong scattering. Furthermore a reliable speed estimate can be made in about 2 s. The method obviously requires additional data - the intensity must be measured with a multi-channel spectrometer. Fortunately such spectrometers are standard equipment at radio observatories. The resulting dynamic spectra can be processed to show the 2-dimensional microstructure and the flow speed. Theory, simulations, and observations will be presented to demonstrate the method. It appears particularly suitable for measuring transients such as coronal mass ejections (CME's) in the interplanetary medium. It will be possible to track many sources with a single antenna, spending only a few seconds on each source, and thus to map the space-time evolution of the CME in turbulence level, flow speed, and anisotropy.

  1. GALILEO RADIO AND PLASMA WAVE OBSERVATIONS AT JUPITER: AN INVITED

    E-print Network

    Gurnett, Donald A.

    GALILEO RADIO AND PLASMA WAVE OBSERVATIONS AT JUPITER: AN INVITED OVERVIEW D. A. Gurnett , W. S. Kurth , A. Roux , C. F. Kennel and S. J. Bolton§ On 7 December 1995 the Galileo spacecraft made a close of the immediate vicinity of Io. The Galileo plasma wave investigation found that the torus was a factor of two

  2. Radio Wave Propagation in Metal Train Compartments MSc thesis in Embedded Systems

    E-print Network

    Langendoen, Koen

    #12;#12;Radio Wave Propagation in Metal Train Compartments MSc thesis in Embedded Systems Faculty Yaowen Khee January 12, 2009 #12;#12;Author Yaowen Khee yb.khee@gmail.com Title Radio Wave Propagation of multiple nodes, each with the ability to communicate using radio waves. The characteristics of the radio

  3. Moreton wave, "EIT wave", and type II radio burst as manifestations of a single wave front

    NASA Astrophysics Data System (ADS)

    Kuzmenko, I. V.; Grechnev, V. V.; Uralov, A. M.

    2011-12-01

    We show that a Moreton wave, an "EIT wave," and a type II radio burst observed during a solar flare of July 13, 2004, might have been a manifestation of a single front of a decelerating shock wave, which appeared in an active region (AR) during a filament eruption. We propose describing a quasi-spheroidal wave propagating upward and along the solar surface by using relations known from a theory of a point-like explosion in a gas whose density changes along the radius according to a power law. By applying this law to fit the drop in density of the coronal plasma enveloping the solar active region, we first managed to bring the measured positions and velocities of surface Moreton wave and "EIT wave" into correspondence with the observed frequency drift rate of the meter type II radio burst. The exponent of the vertical coronal density falloff is selected by fitting the power law to the Newkirk and Saito empirical distributions in the height range of interest. Formal use of such a dependence in the horizontal direction with a different exponent appears to be reasonable up to distances of less than 200 Mm around the eruption center. It is possible to assume that the near-surface shock wave weakens when leaving this radius and finally the active region, entering the region of the quiet Sun where the coronal plasma density and the fast-mode speed are almost constant along the horizontal.

  4. Yerkes Summer Institute 2002 Before we begin our investigations into radio waves you should review the

    E-print Network

    Collar, Juan I.

    Yerkes Summer Institute 2002 Before we begin our investigations into radio waves you should review to spend more time learning about the basic properties of waves and radio so that you will be able to get waves from your favorite radio stations. All waves have certain things in common. Let's look

  5. Ionospheric wave and irregularity measurements using passive radio astronomy techniques

    NASA Technical Reports Server (NTRS)

    Erickson, W. C.; Mahoney, M. J.; Jacobson, A. R.; Knowles, S. H.

    1988-01-01

    The observation of midlatitude structures using passive radio astronomy techniques is discussed, with particular attention being given to the low-frequency radio telescope at the Clark Lake Radio Observatory. The present telescope operates in the 10-125-MHz frequency range. Observations of the ionosphere at separations of a few kilometers to a few hundreds of kilometers by the lines of sight to sources are possible, allowing the determination of the amplitude, wavelength, direction of propagation, and propagation speed of ionospheric waves. Data are considered on large-scale ionospheric gradients and the two-dimensional shapes and sizes of ionospheric irregularities.

  6. Coincidently Searching for Gravitational Waves and Low Frequency Radio Transients

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Yancey, C.; Shawhan, P. S.; Cutchin, S.; Simonetti, J. H.; Bear, B.; Tsai, J.

    2014-01-01

    The transient sky has become an important area of astrophysical study, especially with the appearance of recent fast transients, but little is known about the sources of these transients. One possible approach which can shed light on this area is multi-messenger astronomy using gravitational waves and prompt emission meter-wavelength radio to observe fast transients. This is made possible with gravitational-wave detectors such as LIGO, VIRGO, and GEO (IndIGO and KAGRA proposed or under construction) and phased-array radio-telescopes such LWA, LOFAR, LoFASM, and MWA. This talk presents a method for coincidence of gravitational wave and meter-wavelength radio observations to enable multi-messenger astronomy and discusses the optimization of gravitational-wave and radio sensitivities to attain effective combined observational sensitivities. It is shown that coincidence provides a 52.9% increase to the sensitivity distance for LIGO and a 200% increase to the SNR of radio arrays for particular cases.

  7. Improved spacecraft radio science using an on-board atomic clock: Application to gravitational wave searches

    NASA Astrophysics Data System (ADS)

    Tinto, Massimo; Dick, George J.; Prestage, John D.; Armstrong, J. W.

    2009-05-01

    Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently leading noise sources: phase scintillation noise from the Earth’s atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multilink CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of 3.7×10-14Hz-1/2 for randomly polarized, monochromatic GW signals isotropically distributed over the celestial sphere, over a two-decade (˜0.0001-0.01Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to improve also other radio science experiments (i.e., tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

  8. Improved spacecraft radio science using an on-board atomic clock: Application to gravitational wave searches

    SciTech Connect

    Tinto, Massimo; Dick, George J.; Prestage, John D.; Armstrong, J. W.

    2009-05-15

    Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently leading noise sources: phase scintillation noise from the Earth's atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multilink CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of 3.7x10{sup -14} Hz{sup -1/2} for randomly polarized, monochromatic GW signals isotropically distributed over the celestial sphere, over a two-decade ({approx}0.0001-0.01 Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to improve also other radio science experiments (i.e., tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

  9. Improved spacecraft radio science using an on-board atomic clock: application to gravitational wave searches

    E-print Network

    Massimo Tinto; George J. Dick; John D. Prestage; J. W. Armstrong

    2008-12-13

    Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently-leading noise sources: phase scintillation noise from the Earth's atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multi-link CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of $2.0 \\times 10^{-17}$ for randomly polarized, monochromatic GW signals over a two-decade ($\\sim0.0001-0.01$ Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to also improve other radio science experiments (i.e. tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

  10. On Microwave Radio Scintillation Effects and Space Weather Impacts on Electric Power Supply Systems in Middle Latitudes

    NASA Astrophysics Data System (ADS)

    Babayev, E. S.; Hashimov, A. M.; Asgarov, A. B.; Yusifbeyli, N. A.; Shustarev, P. N.

    2006-12-01

    In this paper results of morphological studies and investigations on revealing of main characteristics of ionospheric scintillation effects experienced for microwave radio signals for the Space-Earth path, its impacts on navigation and communication systems, dependence on the solar and geomagnetic activity, geophysical and other processes/factors are briefly provided to help system designers who are involved in the activities related to the development and functioning of systems, particularly, for consumers in middle geographical latitudes. Ionospheric propagation model computer code was applied for studying of scintillation effects on microwave radio signals used in the area of Azerbaijan for worst case scenario of main space weather and ionosphere parameters. Part of main results of the complex investigations on possible impact of geomagnetic disturbances of various strengths on electric power supply systems in middle latitudes is described. Daily data on power failures and breakdowns that occurred in Baku capital city (Azerbaijan) and surrounded big urban area in years of descending phase of solar 11-year activity cycle was investigated and analyzed.

  11. Excitation of parametric instabilities by radio waves in the ionosphere.

    NASA Technical Reports Server (NTRS)

    Fejer, J. A.; Leer, E.

    1972-01-01

    The excitation of parametric instabilities by radio waves in a magnetoplasma is discussed. A uniform medium is assumed and linear approximations are used. Excitation by a pump wave of ordinary polarization is hardly affected by the magnetic field. Low or zero frequency ion waves and high frequency Langmuir waves are excited simultaneously. For an extraordinary pump wave, the excited high frequency electrostatic waves are in the Bernstein mode. The threshold is slightly higher and excitation can occur only within certain 'allowed' frequency bands. A new type of parametric instability in which the excited waves are electromagnetic in nature and which is more strongly affected by the inhomogeneous nature of the medium is discussed qualitatively.

  12. Solar type III radio bursts modulated by homochromous Alfvén waves

    SciTech Connect

    Zhao, G. Q.; Chen, L.; Wu, D. J.

    2013-12-10

    Solar type III radio bursts and their production mechanisms have been intensively studied in both theory and observation and are believed to be the most important signatures of electron acceleration in active regions. Recently, Wu et al. proposed that the electron-cyclotron maser emission (ECME) driven by an energetic electron beam could be responsible for producing type III bursts and pointed out that turbulent Alfvén waves can greatly influence the basic process of ECME via the oscillation of these electrons in the wave fields. This paper investigates effects of homochromous Alfvén waves (HAWs) on ECME driven by electron beams. Our results show that the growth rate of the O-mode wave will be significantly modulated by HAWs. We also discuss possible application to the formation of fine structures in type III bursts, such as so-called solar type IIIb radio bursts.

  13. X-Shaped Radio Galaxies and the Gravitational Wave Background

    NASA Astrophysics Data System (ADS)

    Hall Roberts, David; Saripalli, Lakshmi; Subrahmanyan, Ravi

    2015-08-01

    Coalescence of super massive black holes (SMBH's) in galactic mergers is potentially the dominant contributor to the low frequency gravitational wave background (GWB). It was proposed by Merritt and Ekers (2002) that X-shaped radio galaxies are signposts of such coalescences, and that their abundance might be used to predict the magnitude of the gravitational wave background. In Roberts et al. (2015) we presented radio images of all 52 X-shaped radio source candidates out of the sample of 100 selected by Cheung (2007) for which archival VLA data were available. These images indicate that at most 21% of the candidates might be genuine X-shaped radio sources that were formed by a restarting of beams in a new direction following a major merger. This suggests that fewer than 1.3% of extended radio sources appear to be candidates for genuine axis reorientations, much smaller than the 7% suggested by Leahy & Parma (1992). Thus the associated gravitational wave background may be substantially smaller than previous estimates. These results can be used to normalize detailed calculations of the SMBH coalescence rate and the GWB.

  14. Radio wave propagation at frequencies exceeding MUF-F2 in the short wave band

    NASA Technical Reports Server (NTRS)

    Ashkaliyev, Y. F.; Bocharov, V. I.

    1972-01-01

    The results of measurements of field strength and signal/noise ratio on experimental ionospheric-scattering short wave radio links are presented. It is shown that the seasonal and diurnal variations of field strength are determined by features of solar and meteoric activity. The role of the sporadic E-layer in propagation of short radio waves at frequencies exceeding MUF-F2 is noted.

  15. Recovery of radioisotopes from nuclear waste for radio-scintillator-luminescence energy applications

    E-print Network

    Bennun, Alfred

    2012-01-01

    Extraction of the light weight radioisotopes (LWR) 89Sr/90Sr, from the expended nuclear bars in the Fukushima reactor, should have decreased the extent of contamination during the course of the accident. 89Sr applications could pay for the extraction of 89Sr/90Sr from nuclear residues. Added value could be obtained by using 89Sr for cancer treatments. Known technologies could be used to relate into innovative ways LWR, to obtain nuclear energy at battery scale. LWR interact by contact with scintillators converting \\beta-radiation into light-energy. This would lead to manufacturing scintillator lamps which operate independently of other source of energy. These lamps could be used to generate photoelectric energy. Engineering of radioisotopes scintillator photovoltaic cells, would lead to devices without moving parts.

  16. Recovery of radioisotopes from nuclear waste for radio-scintillator-luminescence energy applications

    E-print Network

    Alfred Bennun

    2012-08-16

    Extraction of the light weight radioisotopes (LWR) 89Sr/90Sr, from the expended nuclear bars in the Fukushima reactor, should have decreased the extent of contamination during the course of the accident. 89Sr applications could pay for the extraction of 89Sr/90Sr from nuclear residues. Added value could be obtained by using 89Sr for cancer treatments. Known technologies could be used to relate into innovative ways LWR, to obtain nuclear energy at battery scale. LWR interact by contact with scintillators converting \\beta-radiation into light-energy. This would lead to manufacturing scintillator lamps which operate independently of other source of energy. These lamps could be used to generate photoelectric energy. Engineering of radioisotopes scintillator photovoltaic cells, would lead to devices without moving parts.

  17. Short-Wave Radio: An Aid to Language Learning.

    ERIC Educational Resources Information Center

    Lutcavage, Charles P.

    1982-01-01

    Discusses use of short-wave radio broadcasts as method for expanding students' appreciation of practical advantages of language learning. Suggests use of news broadcasts and gives guidelines for using broadcasts such as level of aural comprehension in class. (Author/BK)

  18. On the interaction of radio waves with meteoric plasma

    E-print Network

    Luigi Foschini

    2001-12-16

    In this paper, a meteoric plasma is analyzed from a physical viewpoint, with particular emphasis on its interaction with radio waves. The attention is drawn to some macroscopic characteristics of a meteoric plasma and it is shown that the electron-ion collision frequency is not negligible, as commonly thought.

  19. Tracking the CME-driven Shock Wave on 2012 March 5 and Radio Triangulation of Associated Radio Emission

    NASA Astrophysics Data System (ADS)

    Magdaleni?, J.; Marqué, C.; Krupar, V.; Mierla, M.; Zhukov, A. N.; Rodriguez, L.; Maksimovi?, M.; Cecconi, B.

    2014-08-01

    We present a multiwavelength study of the 2012 March 5 solar eruptive event, with an emphasis on the radio triangulation of the associated radio bursts. The main points of the study are reconstruction of the propagation of shock waves driven by coronal mass ejections (CMEs) using radio observations and finding the relative positions of the CME, the CME-driven shock wave, and its radio signatures. For the first time, radio triangulation is applied to different types of radio bursts in the same event and performed in a detailed way using goniopolarimetric observations from STEREO/Waves and WIND/Waves spacecraft. The event on 2012 March 5 was associated with a X1.1 flare from the NOAA AR 1429 situated near the northeast limb, accompanied by a full halo CME and a radio event comprising long-lasting interplanetary type II radio bursts. The results of the three-dimensional reconstruction of the CME (using SOHO/LASCO, STEREO COR, and HI observations), and modeling with the ENLIL cone model suggest that the CME-driven shock wave arrived at 1 AU at about 12:00 UT on March 7 (as observed by SOHO/CELIAS). The results of radio triangulation show that the source of the type II radio burst was situated on the southern flank of the CME. We suggest that the interaction of the shock wave and a nearby coronal streamer resulted in the interplanetary type II radio emission.

  20. Tracking the CME-driven shock wave on 2012 March 5 and radio triangulation of associated radio emission

    SciTech Connect

    Magdaleni?, J.; Marqué, C.; Mierla, M.; Zhukov, A. N.; Rodriguez, L.; Krupar, V.; Maksimovi?, M.; Cecconi, B.

    2014-08-20

    We present a multiwavelength study of the 2012 March 5 solar eruptive event, with an emphasis on the radio triangulation of the associated radio bursts. The main points of the study are reconstruction of the propagation of shock waves driven by coronal mass ejections (CMEs) using radio observations and finding the relative positions of the CME, the CME-driven shock wave, and its radio signatures. For the first time, radio triangulation is applied to different types of radio bursts in the same event and performed in a detailed way using goniopolarimetric observations from STEREO/Waves and WIND/Waves spacecraft. The event on 2012 March 5 was associated with a X1.1 flare from the NOAA AR 1429 situated near the northeast limb, accompanied by a full halo CME and a radio event comprising long-lasting interplanetary type II radio bursts. The results of the three-dimensional reconstruction of the CME (using SOHO/LASCO, STEREO COR, and HI observations), and modeling with the ENLIL cone model suggest that the CME-driven shock wave arrived at 1 AU at about 12:00 UT on March 7 (as observed by SOHO/CELIAS). The results of radio triangulation show that the source of the type II radio burst was situated on the southern flank of the CME. We suggest that the interaction of the shock wave and a nearby coronal streamer resulted in the interplanetary type II radio emission.

  1. Radio wave propagation in the presence of a Mark D. Casciato, Shadi Oveisgharan, and Kamal Sarabandi

    E-print Network

    Sarabandi, Kamal

    Radio wave propagation in the presence of a coastline Mark D. Casciato, Shadi Oveisgharan June 2003; published 7 October 2003. [1] In this paper the effect of a coastline on radio wave transition on the radio wave are discussed. For the case of both source and observation near the surface

  2. Numerical studies of current generation by radio-frequency traveling waves

    E-print Network

    Karney, Charles

    Numerical studies of current generation by radio-frequency traveling waves Charles F. F. Karney January 1979; final manuscript received 7 May 1979) By injecting radio-frequency traveling waves of the fusion power output. Recently,' the damping of high-phase-velocity radio- frequency traveling waves has

  3. December 23, 2004 High Cadence Radio Observations of an EIT Wave

    E-print Network

    White, Stephen

    December 23, 2004 High Cadence Radio Observations of an EIT Wave S. M. White1 and B. J. Thompson2 ABSTRACT Sensitive radio observations of the 1997 September 24 EIT wave show its velocity to be 830 km s-1 result is that no deceleration is observed during the 4 minutes that the wave is visible in the radio

  4. Verification of particle simulation of radio frequency waves in fusion Animesh Kuley,1,2,a)

    E-print Network

    Lin, Zhihong

    Verification of particle simulation of radio frequency waves in fusion plasmas Animesh Kuley,1,2,a (Received 14 May 2013; accepted 8 October 2013; published online 24 October 2013) Radio frequency (RF) waves. INTRODUCTION The importance of radio frequency (RF) waves as a source for heating and current drive has been

  5. The radio waves and thermal electrostatic noise spectroscopy (SORBET) experiment on BEPICOLOMBO/MMO/PWI

    E-print Network

    Aulanier, Guillaume

    The radio waves and thermal electrostatic noise spectroscopy (SORBET) experiment on BEPICOLOMBO spectrometer designed for the radio and Plasma Waves Instrument onboard BepiColombo/Mercury Magnetospheric noise spectroscopy; Radio and plasma waves; Spacecraft instrumentation; BepiColombo/MMO 0273-1177/$30 Ó

  6. Ulysses radio and plasma wave observations in the Jupiter environment

    NASA Technical Reports Server (NTRS)

    Stone, R. G.; Pedersen, B. M.; Harvey, C. C.; Canu, P.; Cornilleau-Wehrlin, N.; Desch, M. D.; De Villedary, C.; Fainberg, J.; Farrell, W. M.; Goetz, K.

    1992-01-01

    The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of auroral-like hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the Io plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the Io torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed.

  7. Status of RadioWave Neutrino Detection

    NASA Astrophysics Data System (ADS)

    Besson, Dave

    2012-12-01

    As of this writing, there are three dedicated experiments, all based in Antarctica, which seek first-ever measurement of the ultra-high energy neutrino flux at Earth. All three (ANITA, ARA and ARIANNA) exploit the Askaryan Effect to detect the so-called cosmogenic neutrinos which should result from interactions of ultra-high energy baryons with the Cosmic Microwave Background Radiation (CMBR). Photoproduction of those neutrinos, via N? ? ? ? N?+/-, with subsequent weak decays of those pions resulting in neutrinos. In-ice weak and neutral scattering of those neutrinos off ice molecules can yield in a detectable pulse of coherent, radio-frequency radiation. We summarize the three experiments, and discuss prospects.

  8. Electron Acceleration by High Power Radio Waves in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, Paul

    2012-10-01

    At the highest ERP of the High Altitude Auroral Research Program (HAARP) facility in Alaska, high frequency (HF) electromagnetic (EM) waves in the ionosphere produce artificial aurora and electron-ion plasma layers. Using HAARP, electrons are accelerated by high power electrostatic (ES) waves to energies >100 times the thermal temperature of the ambient plasma. These ES waves are driven by decay of the pump EM wave tuned to plasma resonances. The most efficient acceleration process occurs near the harmonics of the electron cyclotron frequency in earth's magnetic field. Mode conversion plays a role in transforming the ES waves into EM signals that are recorded with ground receivers. These diagnostic waves, called stimulated EM emissions (SEE), show unique resonant signatures of the strongest electron acceleration. This SEE also provides clues about the ES waves responsible for electron acceleration. The electron gas is accelerated by high frequency modes including Langmuir (electron plasma), upper hybrid, and electron Bernstein waves. All of these waves have been identified in the scattered EM spectra as downshifted sidebands of the EM pump frequency. Parametric decay is responsible low frequency companion modes such as ion acoustic, lower hybrid, and ion Bernstein waves. The temporal evolution of the scattered EM spectrum indicates development of field aligned irregularities that aid the mode conversion process. The onset of certain spectral features is strongly correlated with glow plasma discharge structures that are both visible with the unaided eye and detectable using radio backscatter techniques at HF and UHF frequencies. The primary goals are to understand natural plasma layers, to study basic plasma physics in a unique ``laboratory with walls,'' and to create artificial plasma structures that can aid radio communications.

  9. Experimental observations of the spatial structure of wave-like disturbances generated in midlatitude ionosphere by high power radio waves

    NASA Astrophysics Data System (ADS)

    Kunitsyn, V.; Andreeva, E.; Padokhin, A. M.; Nazarenko, M.; Frolov, V.; Komrakov, G.; Bolotin, I.

    2012-12-01

    We present the results of the experiments carried out in 2009-2012 on the Sura heating facility (Radio Physical Research Institute, N. Novgorod, Russia) on modification of the midlatitude ionosphere by powerful HF radiowaves. The experiments were conducted using O-mode radiowaves at frequencies lower than critical frequency of the ionospheric F2 layer both in daytime and nighttime ionosphere. Various schemes of the radiation of the heating wave were used including square wave modulation of the effective radiated power (ERP) at various frequencies and power stepping. Radio transmissions of the low- (Parus/Tsikada) and high-orbital (GPS/GLONASS) navigational satellites received at the mobile network of receiving sites were used for the remote sensing of the heated area of the ionosphere. The variations in the slant total electron content (TEC), which are proportional to the reduced phase of navigational signals, were studied for the satellite passes for which ionospheric penetration points crossed the disturbed area during HF heating. The variations in TEC caused by HF heating are identified in a number of examples. It is shown that the GNSS TEC spectra contain frequency components corresponding to the modulation periods of the ERP of the heating wave. The manifestations of the heating-induced variations in TEC are most prominent in the area of magnetic zenith of the pumping wave. Different behavior of TEC variations was observed during nighttime and daytime heating experiments. In daytime conditions the pump wave switched ON causes the increase of TEC while in the nighttime it causes a decrease in TEC. This can be explained by the different contribution of the processes responsible for the increase and decrease of TEC in daytime in nighttime conditions. In this work we also present the first time radiotomographic reconstructions of the spatial structure of the wave-like disturbances, generated in the ionosphere by high-power radio waves radiated by the Sura heater with a square wave modulation of the ERP at a frequency lower than or of the order of the Brunt-Vaisala frequency of the neutral atmosphere. The observed wavelike structures, which are possibly AGWs, diverge from the heated area of the ionosphere (observed like a narrow trough with dimensions corresponding to the diagram pattern of the Sura heater), the spatial period of these disturbances is 200-250 km and they are easily traced up to a distance of 700-800 km from the heated region. These observations are in good agreement with complimentary GPS/GLONASS data. We also present the examples of amplitude scintillations of the signals of low-orbital radio beacons corresponding to small-scale field-aligned irregularities in the heated area of ionosphere. The possibility of generation of electromagnetic waves by moving wave-like structures in ionosphere (like AGWs induced by HF-heating observed in our experiments) is also addressed in this work. The authors are grateful to the staff of the Sura facility for their help in conducting the experiments and acknowledge the support of the Russian Foundation for Basic Research (grants 10-05-01126, 11-02-00374, 11-05-01157, 12-02-31839, 12-05-33065, 12-05-10068), grant of the President of Russian Federation MK-2544.2012.5 and Lomonosov Moscow State University Program of Development.

  10. Waves in Saturn's rings probed by radio occultation

    SciTech Connect

    Rosen, P.A.

    1989-01-01

    Thirty wave features, observed in 3.6 and 13 cm-wavelength optical depth profiles of Saturn's rings obtained by Voyager 1 radio occultation, are analyzed individually and comparatively. Many are the signature of spiral density waves and bending waves excited by gravitational resonances with Saturn's satellites. A new technique for locating waveform extrema, which fits a sinusoid to each half cycle of wave data, quantifies the wavelength variation across a feature. Fitting dispersion models to the derived wavelengths provides new estimates of ambient surface mass density {sigma} in each wave region. For fourteen weak density waves in Ring A, modelling of the waveform near resonance with linear density wave theory gives independent estimates of {sigma}, as well as reliable estimates of resonance location. Measurements of wave amplitude damping give an upper bound for ring thickness 2H, where H is the ring scale height. In the wave regions studied, Rings A, B, and C have 30 {approx lt} {sigma} {approx lt} 70, {sigma} {approx gt} 65, and {sigma} {approximately} 1 g/cm{sup 2}, respectively. Mass loading estimates from waveform modelling are 20 to 40% larger than dispersion-derived values, suggesting accumulation of mass in the wave regions. The average offset of derived wave location from theoretical resonance is about 1 km. Model waveforms of overlapping waves excited by the satellites Janus and Epimethenus agree well with observed morphologies in the linear region near resonance. In Ring C, dispersion analysis indicates that the most prominent wave feature, previously unidentified, is a one-armed spiral wave.

  11. Excitation of Alfven Waves and Pulsar Radio Emission

    E-print Network

    Maxim Lyutikov

    1999-10-04

    We analyze mechanisms of the excitation of Alfv\\'{e}n wave in pulsar magnetospheres as a possible source of pulsar radio emission generation. We find that Cherenkov excitation of obliquely propagating Alfv\\'{e}n waves is inefficient, while excitation at the anomalous cyclotron resonance by the particles from the primary beam and from the tail of the bulk distribution function may have a considerable growth rate. The cyclotron instability on Alfv\\'{e}n waves occurs in the kinetic regime still not very closed to the star: $r \\geq 50 R_{NS}$. We also discuss various mechanisms of conversion of Alfv\\'{e}n waves into escaping radiation. Unfortunately, no decisive conclusion about the effectiveness of such conversion can be made.

  12. Theories of radio emissions and plasma waves. [in Jupiter magnetosphere

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.; Goertz, C. K.

    1983-01-01

    The complex region of Jupiter's radio emissions at decameter wavelengths, the so-called DAM, is considered, taking into account the basic theoretical ideas which underly both the older and newer theories and models. Linear theories are examined, giving attention to direct emission mechanisms, parallel propagation, perpendicular propagation, and indirect emission mechanisms. An investigation of nonlinear theories is also conducted. Three-wave interactions are discussed along with decay instabilities, and three-wave up-conversio. Aspects of the Io and plasma torus interaction are studied, and a mechanism by which Io can accelerate electrons is reviewed.

  13. Data compression for the Cassini radio and plasma wave instrument

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Gurnett, D. A.; Kirchner, D. L.; Kurth, W. S.; Woolliscroft, L. J. C.

    1993-01-01

    The Cassini Radio and Plasma Wave Science experiment will employ data compression to make effective use of the available data telemetry bandwidth. Some compression will be achieved by use of a lossless data compression chip and some by software in a dedicated 80C85 processor. A description of the instrument and data compression system are included in this report. Also, the selection of data compression systems and acceptability of data degradation is addressed.

  14. Langmuir Waves of the August 18, 2010 Solar Radio Burst

    NASA Astrophysics Data System (ADS)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.

    2010-12-01

    On Aug 18, 2010, the STEREO/WAVES experiment on the STEREO Ahead spacecraft observed Type II and Type III solar radio bursts followed by Langmuir waves in-situ, the best example so far of the sort of event that the experiment was designed to analyze. A total of 45 Time Domain Sampler (TDS) events were captured, together with other data. An important aim of S/Waves was to measure the total energy radiated and the total energy in Langmuir waves, in order to estimate the conversion efficiency required to generate the radiated electromagnetic energy and to compare theories of this conversion process. These energies will be discussed. A second aim was to investigate the Langmuir waves themselves. Many of the 45 TDS events show the characteristic modulation usually attributed to decay to and interference with a daughter wave. In some cases, there is a third wave, a “granddaughter”. Some Langmuir waves have the appearance of trapping in a density cavity. Examples of these processes will be presented.

  15. Radio observations of atmospheric gravity waves with Callisto

    NASA Astrophysics Data System (ADS)

    Monstein, C.

    2013-12-01

    On December 12th 2013 NOAA reported between 08:04 and 12:08 only radio noise at 245 MHz observed in San Vito. But some European observatories of the e-Callisto network (Germany, UK and Ireland) observed very strange reverse drifting and v-type bursts which was never recognized by the author before. Private communication with P. Zucca from TCD showed that these strange structures are due to focusing effects in the ionosphere. Interestingly it is possible to observe complex ionospheric behavior with cheap and simple radio-telescopes like Callisto. People who are interested in such kind of observations to study ionospheric gravity waves should generate observing programs for frequencies below 100 MHz, ideally with an additional up-converter for frequencies from 15 MHz - 100 MHz. Callisto again proved to be a powerful tool for solar science and radio-monitoring. Below are shown recent observations from Bir castle in Ireland, Essen in Germany and Glasgow in Scotland. For comparison I added an observation from a LOFAR node from Chibolton in UK which was provided by Richard Fallows from Astron NL. And finally a plot from Nançay radio heliograph, provided by Karl-Heinz Gansel, Dingden Amateur Radio- Astronomy Observatory DARO, Germany. Although Callisto instruments are almost identical, the spectra look completely different, depending on their geographical longitude and latitude.

  16. Radio fiber bursts and fast magnetoacoustic wave trains

    NASA Astrophysics Data System (ADS)

    Karlický, M.; Mészárosová, H.; Jelínek, P.

    2013-02-01

    Aims: We present a model for dm-fiber bursts that is based on assuming fast sausage magnetoacoustic wave trains that propagate along a dense vertical filament or current sheet. Methods: Eight groups of dm-fiber bursts that were observed during solar flares were selected and analyzed by the wavelet analysis method. To model these fiber bursts we built a semi-empirical model. We also did magnetohydrodynamic simulations of a propagation of the magnetoacoustic wave train in a vertical and gravitationally stratified current sheet. Results: In the wavelet spectra of the fiber bursts computed at different radio frequencies we found the wavelet tadpoles, whose head maxima have the same frequency drift as the drift of fiber bursts. It indicates that the drift of these fiber bursts can be explained by the propagating fast sausage magnetoacoustic wave train. Using new semi-empirical and magnetohydrodynamic models with a simple radio emission model we generated the artificial radio spectra of the fiber bursts, which are similar to the observed ones.

  17. Verification of nonlinear particle simulation of radio frequency waves A. Kuley,1,a)

    E-print Network

    Lin, Zhihong

    Verification of nonlinear particle simulation of radio frequency waves in tokamak A. Kuley,1,a) Z://dx.doi.org/10.1063/1.4934606] I. INTRODUCTION Magnetic fusion devices rely on radio frequency (RF) waves 2015; accepted 13 October 2015; published online 27 October 2015) Nonlinear simulation model for radio

  18. Scattering of radio frequency waves by blobs in tokamak plasmas

    SciTech Connect

    Ram, Abhay K.; Hizanidis, Kyriakos; Kominis, Yannis

    2013-05-15

    The density fluctuations and blobs present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction, reflection, diffraction, and coupling to other plasma waves. This, in turn, affects the spectrum of the RF waves and the electromagnetic power that reaches the core of the plasma. The usual geometric optics analysis of RF scattering by density blobs accounts for only refractive effects. It is valid when the amplitude of the fluctuations is small, of the order of 10%, compared to the background density. In experiments, density fluctuations with much larger amplitudes are routinely observed, so that a more general treatment of the scattering process is needed. In this paper, a full-wave model for the scattering of RF waves by a blob is developed. The full-wave approach extends the range of validity well beyond that of geometric optics; however, it is theoretically and computationally much more challenging. The theoretical procedure, although similar to that followed for the Mie solution of Maxwell's equations, is generalized to plasmas in a magnetic field. Besides diffraction and reflection, the model includes coupling to a different plasma wave than the one imposed by the external antenna structure. In the model, it is assumed that the RF waves interact with a spherical blob. The plasma inside and around the blob is cold, homogeneous, and imbedded in a uniform magnetic field. After formulating the complete analytical theory, the effect of the blob on short wavelength electron cyclotron waves and longer wavelength lower hybrid waves is studied numerically.

  19. Optical detection of radio waves through a nanomechanical transducer

    NASA Astrophysics Data System (ADS)

    Bagci, T.; Simonsen, A.; Schmid, S.; Villanueva, L. G.; Zeuthen, E.; Appel, J.; Taylor, J. M.; Sørensen, A.; Usami, K.; Schliesser, A.; Polzik, E. S.

    2014-03-01

    Low-loss transmission and sensitive recovery of weak radio-frequency and microwave signals is a ubiquitous challenge, crucial in radio astronomy, medical imaging, navigation, and classical and quantum communication. Efficient up-conversion of radio-frequency signals to an optical carrier would enable their transmission through optical fibres instead of through copper wires, drastically reducing losses, and would give access to the set of established quantum optical techniques that are routinely used in quantum-limited signal detection. Research in cavity optomechanics has shown that nanomechanical oscillators can couple strongly to either microwave or optical fields. Here we demonstrate a room-temperature optoelectromechanical transducer with both these functionalities, following a recent proposal using a high-quality nanomembrane. A voltage bias of less than 10 V is sufficient to induce strong coupling between the voltage fluctuations in a radio-frequency resonance circuit and the membrane's displacement, which is simultaneously coupled to light reflected off its surface. The radio-frequency signals are detected as an optical phase shift with quantum-limited sensitivity. The corresponding half-wave voltage is in the microvolt range, orders of magnitude less than that of standard optical modulators. The noise of the transducer--beyond the measured Johnson noise of the resonant circuit--consists of the quantum noise of light and thermal fluctuations of the membrane, dominating the noise floor in potential applications in radio astronomy and nuclear magnetic imaging. Each of these contributions is inferred to be when balanced by choosing an electromechanical cooperativity of with an optical power of 1 mW. The noise temperature of the membrane is divided by the cooperativity. For the highest observed cooperativity of , this leads to a projected noise temperature of 40 mK and a sensitivity limit of . Our approach to all-optical, ultralow-noise detection of classical electronic signals sets the stage for coherent up-conversion of low-frequency quantum signals to the optical domain.

  20. Cassini Radio and Plasma Wave Observations at Saturn

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Hospodarsky, G. B.; Persoon, A. M.; Averkamp, T. F.; Ceccni, B.; Lecacheux, A.; Zarka, P.; Canu, P.; Cornilleau-Wehrlin, N.

    2005-01-01

    Results are presented from the Cassini radio and plasma wave instrument during the approach and first few orbits around Saturn. During the approach the intensity modulation of Saturn Kilometric Radiation (SKR) showed that the radio rotation period of Saturn has increased to 10 hr 45 min plus or minus 36 sec, about 6 min longer than measured by Voyager in 1980-81. Also, many intense impulsive radio signals called Saturn Electrostatic Discharges (SEDs) were detected from saturnian lightning, starting as far as 1.08 AU from Saturn, much farther than terrestrial lightning can be detected from Earth. Some of the SED episodes have been linked to cloud systems observed in Saturn s atmosphere by the Cassini imaging system. Within the magnetosphere plasma wave emissions have been used to construct an electron density profile through the inner region of the magnetosphere. With decreasing radial distance the electron density increases gradually to a peak of about 100 per cubic centimeter near the outer edge of the A ring, and then drops precipitously to values as low as .03 per cubic centimeter over the rings. Numerous nearly monochromatic whistler-mode emissions were observed as the spacecraft passed over the rings that are believed to be produced by meteoroid impacts on the rings. Whistlermode emissions, similar to terrestrial auroral hiss were also observed over the rings, indicating that an electrodynamic interaction, similar to auroral particle acceleration, may be occurring in or near the rings. During the Titan flybys Langmuir probe and plasma wave measurements provided observations of the density and temperature in Titan's ionosphere.

  1. Hertz and the Discovery of Radio Waves and the Photoelectric Effect.

    ERIC Educational Resources Information Center

    Spradley, Joseph L.

    1988-01-01

    Describes the discoveries by Hertz historically, such as photoelectric effect, radio waves, their impact on modern physics and some applications. Presents several diagrams and two chronological tables. (YP)

  2. Targeted searches for gravitational waves from radio pulsars

    E-print Network

    Réjean J. Dupuis

    2005-09-06

    An overview of the searches for gravitational waves from radio pulsars with LIGO and GEO is given. We give a brief description of the algorithm used in these targeted searches and provide end-to-end validation of the technique through hardware injections. We report on some aspects of the recent S3/S4 LIGO and GEO search for signals from several pulsars. The gaussianity of narrow frequency bands of S3/S4 LIGO data, where pulsar signals are expected, is assessed with Kolmogorov-Smirnov tests. Preliminary results from the S3 run with a network of four detectors are given for pulsar J1939+2134.

  3. Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices

    SciTech Connect

    Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Hensley, Walter K.; Kouzes, Richard T.; Schweppe, John E.

    2007-03-11

    Lanthanum bromide (LaBr3:Ce) scintillators offer significantly better resolution [<3 percent at 662 kilo-electron volt (keV)] relative to sodium iodide [NaI(Tl)] but contain internal radioactivity that contributes to spectral counts. LaBr3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5 ´ 1.5 inch LaBr¬3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5 ´ 2.2 inch NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision?). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal activity due to 138La in the LaBr3:Ce detector exists and NaI(Tl) consistently outperformed LaBr3:Ce.

  4. Comparison of LaBr 3:Ce and NAI(Tl) scintillators for radio-isotope identification devices

    NASA Astrophysics Data System (ADS)

    Milbrath, B. D.; Choate, B. J.; Fast, J. E.; Hensley, W. K.; Kouzes, R. T.; Schweppe, J. E.

    2007-03-01

    Lanthanum bromide (LaBr 3:Ce) scintillators offer significantly better resolution (<3 percent at 662 keV) relative to sodium iodide (NaI(Tl)) but contain internal radioactivity that contributes to spectral counts. LaBr 3:Ce has recently become available commercially in sizes large enough for the hand-held radio-isotope identification device (RIID) market. To study its potential for RIIDs, a series of measurements were performed comparing a 1.5×1.5-in. LaBr 3:Ce detector with an Exploranium GR-135 RIID, which contains a 1.5×2.2-in. NaI(Tl) detector. Measurements were taken for short time frames and included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision™). In general, the LaBr 3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr 3:Ce detector was usually two to three times faster. The notable exception was for 40K-containing NORM where interfering internal activity due to 138La in the LaBr 3:Ce detector exists and NaI(Tl) consistently outperformed LaBr 3:Ce.

  5. Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices

    SciTech Connect

    Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Kouzes, Richard T.; Schweppe, John E.

    2005-10-23

    LaBr3:Ce scintillators offer significantly better resolution (< 3% at 662 keV) relative to NaI(Tl) and have recently become commercially available in sizes large enough for the handheld, Radio-Isotope Identification Device (RIID) market. Drawbacks to lanthanum halide detectors, however, include internal radioactivity contributing to spectral counts, and a low-energy response which can cause detector resolution to be worse than that of NaI(Tl) below 100 keV. To study the potential of this new material for RIIDs we performed a series of measurements comparing a 1.5² ´ 1.5² LaBr¬3:Ce detector with an Exploranium GR-135 RIID, which contains a 1.5² ´ 2.2² NaI(Tl) detector. Measurements were taken for short timeframes, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. Some measurements were non-contact, involving short distances or cargo shielding scenarios. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope-identification software (ORTEC ScintiVision).

  6. Upper limits on gravitational wave emission from 78 radio pulsars

    E-print Network

    The LIGO Scientific Collaboration; B. Abbott; M. Kramer; A. G. Lyne

    2007-10-12

    We present upper limits on the gravitational wave emission from 78 radio pulsars based on data from the third and fourth science runs of the LIGO and GEO600 gravitational wave detectors. The data from both runs have been combined coherently to maximise sensitivity. For the first time pulsars within binary (or multiple) systems have been included in the search by taking into account the signal modulation due to their orbits. Our upper limits are therefore the first measured for 56 of these pulsars. For the remaining 22, our results improve on previous upper limits by up to a factor of 10. For example, our tightest upper limit on the gravitational strain is 2.6e-25 for PSRJ1603-7202, and the equatorial ellipticity of PSRJ2124-3358 is less than 10^{-6}. Furthermore, our strain upper limit for the Crab pulsar is only 2.2 times greater than the fiducial spin-down limit.

  7. Radio Wave Propagation Handbook for Communication on and Around Mars

    NASA Technical Reports Server (NTRS)

    Ho, Christian; Golshan, Nasser; Kliore, Arvydas

    2002-01-01

    This handbook examines the effects of the Martian environment on radio wave propagation on Mars and in the space near the planet. The environmental effects include these from the Martian atmosphere, ionosphere, global dust storms, aerosols, clouds, and geomorphologic features. Relevant Martian environmental parameters were extracted from the measurements of Mars missions during the past 30 years, especially from Mars Pathfinder and Mars Global Surveyor. The results derived from measurements and analyses have been reviewed through an extensive literature search. The updated parameters have been theoretically analyzed to study their effects on radio propagation. This handbook also provides basic information about the entire telecommunications environment on and around Mars for propagation researchers, system engineers, and link analysts. Based on these original analyses, some important recommendations have been made, including the use of the Martian ionosphere as a reflector for Mars global or trans-horizon communication between future Martian colonies, reducing dust storm scattering effects, etc. These results have extended our wave propagation knowledge to a planet other than Earth; and the tables, models, and graphics included in this handbook will benefit telecommunication system engineers and scientific researchers.

  8. First tsunami gravity wave detection in ionospheric radio occultation data

    DOE PAGESBeta

    Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.

    2015-05-09

    After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing themore »vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.« less

  9. First tsunami gravity wave detection in ionospheric radio occultation data

    SciTech Connect

    Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.

    2015-05-09

    After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing the vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.

  10. Broadband Ionospheric Scintillation Measurements from Space

    NASA Astrophysics Data System (ADS)

    Suszcynsky, D. M.; Light, M. E.; Pigue, M. J.

    2014-12-01

    The U.S. Department of Energy's Radio Frequency Propagation (RFProp) experiment consists of a satellite-based radio receiver suite to study various aspects of trans-ionospheric signal propagation and detection in four frequency bands, 2 - 55 MHz, 125 - 175 MHz, 365 - 415 MHz and 825 - 1100 MHz. In this paper, we present an overview of the RFProp on-orbit research and analysis effort with particular focus on an equatorial scintillation experiment called ESCINT. The 3-year ESCINT project is designed to characterize equatorial ionospheric scintillation in the upper HF and lower VHF portions of the radio spectrum (20 - 150 MHz). Both a 40 MHz continuous wave (CW) signal and 30 - 42 MHz swept frequency signal are transmitted to the satellite receiver suite from the Reagan Test Site at Kwajalein Atoll in the Marshall Islands (8.7° N, 167.7° E) in four separate campaigns centered on the 2014 and 2015 equinoxes. Results from the first campaign conducted from April 22 - May 15, 2014 will be presented including (a) coherence bandwidth measurements over a full range of transmission frequencies and scintillation activity levels, (b) spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities, and (c) supporting ray-trace simulations. The broadband nature of the measurements is found to offer unique insight into both the structure of ionospheric irregularities and their impact on HF/VHF trans-ionospheric radio wave propagation.

  11. Z mode waves as the source of Saturn narrowband radio emissions

    E-print Network

    Gurnett, Donald A.

    Z mode waves as the source of Saturn narrowband radio emissions ShengYi Ye,1 J. D. Menietti,1 G present the first magnetic field measurements of Saturn narrowband emissions validating. S. Kurth (2010), Z mode waves as the source of Saturn narrowband radio emissions, J. Geophys. Res

  12. Walkie-Talkie Measurements for the Speed of Radio Waves in Air

    ERIC Educational Resources Information Center

    Dombi, Andra; Tunyagi, Arthur; Neda, Zoltan

    2013-01-01

    A handheld emitter-receiver device suitable for the direct estimation of the velocity of radio waves in air is presented. The velocity of radio waves is measured using the direct time-of-flight method, without the need for any tedious and precise settings. The results for two measurement series are reported. Both sets of results give an estimate…

  13. Grating formation by a high power radio wave in near-equator ionosphere

    SciTech Connect

    Singh, Rohtash; Sharma, A. K.; Tripathi, V. K.

    2011-11-15

    The formation of a volume grating in the near-equator regions of ionosphere due to a high power radio wave is investigated. The radio wave, launched from a ground based transmitter, forms a standing wave pattern below the critical layer, heating the electrons in a space periodic manner. The thermal conduction along the magnetic lines of force inhibits the rise in electron temperature, limiting the efficacy of heating to within a latitude of few degrees around the equator. The space periodic electron partial pressure leads to ambipolar diffusion creating a space periodic density ripple with wave vector along the vertical. Such a volume grating is effective to cause strong reflection of radio waves at a frequency one order of magnitude higher than the maximum plasma frequency in the ionosphere. Linearly mode converted plasma wave could scatter even higher frequency radio waves.

  14. Radio Wave Scattering in the Outer Heliosphere: Preliminary Calculations

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    Detailed first estimates are presented of angular broadening in the outer heliosphere due to scattering of radio waves by density irregularities. The application is to the 2-3 kHz radiation observed by Voyager. Two plausible turbulence models, which account very well for scattering within 1 AU, are extrapolated beyond 10 AU. Both models predict significant angular broadening in the outer heliosphere, accounting semi- quantitatively alone for the source sizes inferred from roll modulation data. Predictions are presented for radial variations in the apparent source size if scattering is important. Comparisons with available data argue that scattering is important (and indeed is the dominant contributor to the apparent source size) and that the radiation source is located in the outer heliosphere. Other evidence that scattering is important, such as the fluctuations in apparent source direction and intensity, are also identified. The effects of scattering should be included in future analyses of the 2-3 kHz emissions.

  15. Wave propagation simulation of radio occultations based on ECMWF refractivity profiles

    NASA Astrophysics Data System (ADS)

    Benzon, Hans-Henrik; Høeg, Per

    2015-08-01

    This paper describes a complete radio occultation simulation environment, including realistic refractivity profiles, wave propagation modeling, instrument modeling, and bending angle retrieval. The wave propagator is used to simulate radio occultation measurements. The radio waves are propagated through a refractivity field which has been calculated with the use of numerical weather prediction models. The numerical weather prediction model used in this paper is a model from the European Centre for Medium-Range Weather Forecasts (ECMWF). The wave propagator has been used to simulate a number of radio occultations. The output from the wave propagator simulator is used as input to a Full Spectrum Inversion retrieval module which calculates geophysical parameters. These parameters can be compared to the ECMWF atmospheric profiles. The comparison can be used to reveal system errors and get a better understanding of the physics. The wave propagation simulations will in this paper also be compared to real measurements. These radio occultations have been exposed to the same atmospheric conditions as the radio occultations simulated by the wave propagator. This comparison reveals that precise radio occultations can be simulated when the simulations are based on wave propagation and refractivity field inputs from a numerical weather prediction model.

  16. GPS phase scintillation correlated with auroral forms

    NASA Astrophysics Data System (ADS)

    Hampton, D. L.; Azeem, S. I.; Crowley, G.; Santana, J.; Reynolds, A.

    2013-12-01

    The disruption of radio wave propagation due to rapid changes in electron density caused by auroral precipitation has been observed for several decades. In a few cases the disruption of GPS signals has been attributed to distinct auroral arcs [Kintner, 2007; Garner, 2011], but surprisingly there has been no systematic study of the characteristics of the auroral forms that cause GPS scintillation. In the Fall of 2012 ASTRA deployed four CASES GPS receivers at UAF observatories in Alaska (Kaktovik, Fort Yukon, Poker Flat and Gakona) specifically to address the effects of auroral activity on the high latitude ionosphere. We have initiated an analysis that compares the phase scintillation, recorded at high cadence, with filtered digital all-sky camera data to determine the auroral morphology and electron precipitation parameters that cause scintillation. From correlation studies from a single site (Poker Flat), we find that scintillation is well correlated with discrete arcs that have high particle energy flux (power per unit area), and not as well correlated with pulsating forms which typically have high characteristic energy, but lower energy flux . This indicates that the scintillation is correlated with the magnitude of the change in total electron density as expected. We will also report on ongoing work where we correlate the scintillation from the Fort Yukon receiver with the all-sky images at Poker Flat to determine the altitude that produces the greatest disturbance. These studies are aimed at a model that can predict the expected local disturbance to navigation due to auroral activity.

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

    SciTech Connect

    Ram, A. K.; Hizanidis, K.; Kominis, Y.

    2011-12-23

    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.

  18. ENERGY EFFICIENT MILLIMETER WAVE RADIO LINK ESTABLISHMENT WITH SMART ARRAY ANTENNAS

    E-print Network

    Baras, John S.

    1 ENERGY EFFICIENT MILLIMETER WAVE RADIO LINK ESTABLISHMENT WITH SMART ARRAY ANTENNAS Behnam of two millimeter wave transceiver nodes A and B. We assume that each node is equipped with a circular. INTRODUCTION Millimeter wave technology is becoming increasingly important in many military and commercial

  19. Comparison of LaBr3:Ce and NaI(Tl) Scintillators for Radio-Isotope Identification Devices

    SciTech Connect

    Milbrath, Brian D.; Choate, Bethany J.; Fast, Jim E.; Hensley, Walter K.; Kouzes, Richard T.; Schweppe, John E.

    2006-07-31

    Lanthanum halide (LaBr3:Ce) scintillators offer significantly better resolution (<3 percent at 662 kilo-electron volt [keV]) relative to sodium iodide (NaI(Tl)) and have recently become commercially available in sizes large enough for the hand-held radio-isotope identification device (RIID) market. There are drawbacks to lanthanum halide detectors, however. These include internal radioactivity that contributes to spectral counts and a low-energy response that can cause detector resolution to be lower than that of NaI(Tl) below 100 keV. To study the potential of this new material for RIIDs, we performed a series of measurements comparing a 1.5?1.5 inch LaBr?3:Ce detector with an Exploranium GR 135 RIID, which contains a 1.5-2.2 inch NaI(Tl) detector. Measurements were taken for short time frames, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM), typically found in cargo, and special nuclear materials. Some measurements were noncontact, involving short distances or cargo shielding scenarios. To facilitate direct comparison, spectra from the different detectors were analyzed with the same isotope identification software (ORTEC ScintiVision TM). In general, the LaBr3:Ce detector was able to find more peaks and find them faster than the NaI(Tl) detector. To the same level of significance, the LaBr3:Ce detector was usually two to three times faster. The notable exception was for 40K containing NORM where interfering internal contamination in the LaBr3:Ce detector exist. NaI(Tl) consistently outperformed LaBr3:Ce for this important isotope. LaBr3:Ce currently costs much more than NaI(Tl), though this cost-difference is expected to diminish (but not completely) with time. As is true of all detectors, LaBr3:Ce will need to be gain-stabilized for RIID applications. This could possibly be done using the internal contaminants themselves. It is the experience of the authors that peak finding software in RIIDs needs to be improved, regardless of the detector material.

  20. Characteristics of coronal shock waves and solar type 2 radio bursts

    NASA Technical Reports Server (NTRS)

    Mann, G.; Classen, H.-T.

    1995-01-01

    In the solar corona shock waves generated by flares and/or coronal mass ejections can be observed by radio astronomical methods in terms of solar type 2 radio bursts. In dynamic radio spectra they appear as emission stripes slowly drifting from high to low frequencies. A sample of 25 solar type 2 radio bursts observed in the range of 40 - 170 MHz with a time resolution of 0.1 s by the new radiospectrograph of the Astrophvsikalisches Institut Potsdam in Tremsdorf is statistically investigated concerning their spectral features, i.e, drift rate, instantaneous bandwidth, and fundamental harmonic ratio. In-situ plasma wave measurements at interplanetary shocks provide the assumption that type 2 radio radiation is emitted in the vicinity of the transition region of shock waves. Thus, the instantaneous bandwidth of a solar type 2 radio burst would reflect the density jump across the associated shock wave. Comparing the inspection of the Rankine-Hugoniot relations of shock waves under coronal circumstances with those obtained from the observational study, solar type 2 radio bursts should be regarded to be generated by weak supercritical, quasi-parallel, fast magnetosonic shock waves in the corona.

  1. Low Frequency Radio-wave System for subsurface investigation

    NASA Astrophysics Data System (ADS)

    Soldovieri, Francesco; Gennarelli, Gianluca; Kudelya, Anatoliy; Denisov, Alexander

    2015-04-01

    Low frequency radio-wave methods (RWM) allow subsurface investigations in terms of lithological structure characterization, detection of filtration flows of ground water, anthropogenic and natural cavities. In this contribution, we present a RWM that exploits two coils working at frequencies of few MHz as transmitting and receiving antennas. The basic principle of this inductive method is as follows. The primary alternating electromagnetic field radiated by the transmitting coil induces eddy currents in the subsurface mainly due to the conductivity anomalies. These eddy currents generate a secondary (scattered) magnetic field which overlaps to the incident magnetic field and is detected by the receiving coil. Despite the simple operation of the system, the complexity of the electromagnetic scattering phenomenon at hand must be properly modeled to achieve adequate performance. Therefore, an advanced data processing technique, belonging to the class of the inverse scattering approaches, has been developed by the authors in a full 3D geometry. The proposed method allows to deal with data collected on a scanning surface under a dipole inductive profiling (DIP) modality, where the transmitting/receiving coils are moved simultaneously with fixed offset (multi-bistatic configuration). The hardware, called Dipole Inductive Radio-wave System (DIRS), is composed by an electronic unit and transmitting and receiving loop antennas radiating at frequencies of few MHz (2-4 MHz), which are installed on theodolite supports. The compactness of DIRS and its robustness to external electromagnetic interference offers the possibility to perform geophysical research up to the depth of some tens of meters and under several types of ground and water surfaces, vegetation, and weather conditions. The light weight and small size of system (the single antenna with support weights about 5 kg and has a diameter of 0.5m) allows two operators to perform geophysical research without disturbing the surface integrity of investigated ground massif. The value of base and the value of voltage induced on the digital voltmeter of the receiver are stored in memory on a SD-card for a subsequent visualization and processing. Realistic cases of application of the DIRS system enhanced by the inverse scattering approach will be presented at the conference with regard to the geological characterization of a mine shaft and an archaeological site.

  2. Analytical study of nighttime scintillations using GPS at low latitude station Bhopal

    NASA Astrophysics Data System (ADS)

    Maski, Kalpana; Vijay, S. K.

    2015-07-01

    Sporadically structured ionosphere (i.e. in-homogeneities in refractive index) can cause fluctuations (due to refraction effects) on the radio signal that is passing through it. These fluctuations are called ionospheric scintillations. Low latitude region is suitable for studying these scintillations. The influence of the ionosphere on the propagation of the radio wave becomes very marked with reference to communication or navigational radio system at very low frequency (VLF) to a high frequency (HF), which operate over the distances of 1000 km or more. Radio wave communication at different frequencies depends on structure of the ionosphere. With the advent of the artificial satellites, they are used as a prime mode of radio wave communication. Some natural perturbation termed as irregularities, are present in the form of electron density of the ionosphere that cause disruption in the radio and satellite communications. Therefore the study of the ionospheric irregularities is of practical importance, if one wishes to understand the upper atmosphere completely. In order to make these communications uninterrupted the knowledge of irregularities, which are present in the ionosphere are very important. These irregularities can be located and estimated with the help of Ionospheric TEC and Scintillation. Scintillation is generally confined to nighttime hours, particularly around equatorial and low latitudes

  3. Put a Short-Wave Radio in Your Foreign Language Classroom

    ERIC Educational Resources Information Center

    Oksenholt, Svein

    1977-01-01

    Advantages of the short-wave radio as a supplement to foreign language instruction as well as practical hints on wavelength, antenna, and techniques for use are provided. Selective annotated bibliography. (STS)

  4. Jupiter: As a planet. [its physical characteristics and radio waves emitted from Jupiter

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The planet Jupiter, its planetary mass and atmosphere, radio waves emitted from Jupiter, thermal radiation, internal structure of Jupiter, and the possibility of life on Jupiter are discussed. Educational study projects are included.

  5. A linear radio wave velocity model on polythermal glaciers

    NASA Astrophysics Data System (ADS)

    Ai, Songtao; Wang, Zemin; Geng, Hong

    2015-04-01

    The glaciers in Svalbard are mostly polythermal type. On these polythermal glaciers, the radio wave velocity (RWV) of ground penetrating radar (GPR) is variable, and the RWV is an important parameter for the ice volume estimation. But the ice volume estimation usually uses a single RWV for one whole glacier in order to simplify the calculation. How about the difference between the actual volume and the estimated result? We used a linear RWV model, derived from common mid-point (CMP) profiles of GPR measurement, to simulate the RWV for each GPR trace on Pedersenbreen in Svalbard. Then a relative accurate volume of glacier Pedersenbreen was acquired. From which we found the difference among those volumes calculated from a single RWV, three RWVs and our RWV model. Our RWV model for polythermal glaciers refined the volume estimation and enhanced the precision in mass change study. And the difference between different models could raise an error up to 10% of the volume results. Moreover, the fixed RWV usually used was probably larger than the actual one in those polythermal glaciers. Acknowledgements: This work was supported by the National Natural Science Foundation of China(41476162) and the Chinese Polar Environment Comprehensive Investigation & Assessment Programmes.

  6. New theoretical aspects of potential radio wave emission from Jupiter like exoplanets

    NASA Astrophysics Data System (ADS)

    Weber, Christof; Rucker, Helmut; Vocks, Christian

    2015-04-01

    The UTR-2 (Ukrainian T-shaped Radio Telescope 2nd generation), LOFAR (Low Frequency Array) or the upgrade of LOFAR in Nancay (the NENUFAR project) are promising facilities with sensitivities sufficiently low to be able to detect radio emission from exoplanets, especially from so-called Hot Jupiters. These are Jovian like planets very close to their host star (about 0.045 AU) and their radio emission is expected to be up to 10E5 times higher than the emission from Jupiter in our solar system. Also recent investigations of the possibility of moons around a Jovian exoplanet (an analog of the Io-Jupiter system) are promising candidates amongst the exoplanets for a future detection of exoplanetary radio emission. As is well known Io triggers radio emission up to 40 MHz in the Jovian case, a frequency which lies well above the ionospheric cutoff of 10 MHz and thus can be measured with ground-based facilities on Earth. We present simulation results for wave growth rates at Jupiter-like exoplanets orbiting at distances smaller than 0.1 AU from their parent star. Under sophisticated assumptions for the plasma environment at these exoplanets we find that the cyclotron maser instability (CMI), the process which is very likely responsible for the generation of radio waves in our solar system, produces radio waves which can propagate away from the planet. Furthermore we check the influence of a magnetodisc at Hot Jupiters on the possible power of the emitted radio waves.

  7. Research to Operations of Ionospheric Scintillation Detection and Forecasting

    NASA Astrophysics Data System (ADS)

    Jones, J.; Scro, K.; Payne, D.; Ruhge, R.; Erickson, B.; Andorka, S.; Ludwig, C.; Karmann, J.; Ebelhar, D.

    Ionospheric Scintillation refers to random fluctuations in phase and amplitude of electromagnetic waves caused by a rapidly varying refractive index due to turbulent features in the ionosphere. Scintillation of transionospheric UHF and L-Band radio frequency signals is particularly troublesome since this phenomenon can lead to degradation of signal strength and integrity that can negatively impact satellite communications and navigation, radar, or radio signals from other systems that traverse or interact with the ionosphere. Although ionospheric scintillation occurs in both the equatorial and polar regions of the Earth, the focus of this modeling effort is on equatorial scintillation. The ionospheric scintillation model is data-driven in a sense that scintillation observations are used to perform detection and characterization of scintillation structures. These structures are then propagated to future times using drift and decay models to represent the natural evolution of ionospheric scintillation. The impact on radio signals is also determined by the model and represented in graphical format to the user. A frequency scaling algorithm allows for impact analysis on frequencies other than the observation frequencies. The project began with lab-grade software and through a tailored Agile development process, deployed operational-grade code to a DoD operational center. The Agile development process promotes adaptive promote adaptive planning, evolutionary development, early delivery, continuous improvement, regular collaboration with the customer, and encourage rapid and flexible response to customer-driven changes. The Agile philosophy values individuals and interactions over processes and tools, working software over comprehensive documentation, customer collaboration over contract negotiation, and responding to change over following a rigid plan. The end result was an operational capability that met customer expectations. Details of the model and the process of operational integration are discussed as well as lessons learned to improve performance on future projects.

  8. Ulysses observations of wave activity at interplanetary shocks and implications for type II radio bursts

    SciTech Connect

    Lengyel-Frey, D.; Thejappa, G.; MacDowall, R.J.; Stone, R.G.; Phillips, J.L.

    1997-02-01

    We present the first quantitative investigation of interplanetary type II radio emission in which in situ waves measured at interplanetary shocks are used to compute radio wave intensities for comparison with type II observations. This study is based on in situ measurements of 42 in-ecliptic forward shocks as well as 10 intervals of type II emission observed by the Ulysses spacecraft between 1 AU and 5 AU. The analysis involves comparisons of statistical properties of type II bursts and in situ waves. Most of the 42 shocks are associated with the occurrence of electrostatic waves near the time of shock passage at Ulysses. These waves, which are identified as electron plasma waves and ion acoustic-like waves, are typically most intense several minutes before shock passage. This suggests that wave-wave interactions might be of importance in electromagnetic wave generation and that type II source regions are located immediately upstream of the shocks. We use the in situ wave measurements to compute type II brightness temperatures, assuming that emission at the fundamental of the electron plasma frequency is generated by the merging of electron plasma waves and ion acoustic waves or the decay of electron plasma waves into ion acoustic and transverse waves. Second harmonic emission is assumed to be produced by the merging of electron plasma waves. The latter mechanism requires that a portion of the electron plasma wave distribution is backscattered, presumably by density inhomogeneities in regions of observed ion acoustic wave activity. The computed type II brightness temperatures are found to be consistent with observed values for both fundamental and second harmonic emission, assuming that strong ({approx_equal}10{sup {minus}4}V/m) electron plasma waves and ion acoustic waves are coincident and that the electron plasma waves have phase velocities less than about 10 times the electron thermal velocity. (Abstract Truncated)

  9. Tropospheric scintillation prediction models for a high elevation angle based on measured data from a tropical region

    NASA Astrophysics Data System (ADS)

    Abdul Rahim, Nadirah Binti; Islam, Md. Rafiqul; J. S., Mandeep; Dao, Hassan; Bashir, Saad Osman

    2013-12-01

    The recent rapid evolution of new satellite services, including VSAT for internet access, LAN interconnection and multimedia applications, has triggered an increasing demand for bandwidth usage by satellite communications. However, these systems are susceptible to propagation effects that become significant as the frequency increases. Scintillation is the rapid signal fluctuation of the amplitude and phase of a radio wave, which is significant in tropical climates. This paper presents the analysis of the tropospheric scintillation data for satellite to Earth links at the Ku-band. Twelve months of data (January-December 2011) were collected and analyzed to evaluate the effect of tropospheric scintillation. Statistics were then further analyzed to inspect the seasonal, worst-month, diurnal and rain-induced scintillation effects. By employing the measured scintillation data, a modification of the Karasawa model for scintillation fades and enhancements is proposed based on data measured in Malaysia.

  10. Antenna Construction & Propagation of Radio Waves, 5-1. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Marine Corps, Washington, DC.

    These military-developed curriculum materials consist of five individualized, self-paced chapters dealing with antenna construction and propagation of radio waves. Covered in the individual lessons are the following topics: basic electricity; antenna transmission-line fundamentals; quarter-wave antennas, half-wave antennas, and associated radio

  11. Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab geometry

    E-print Network

    Vellekoop, Michel

    Continuous wave near-infrared atomic Xe laser excited by a radio frequency discharge in a slab excited by a radio frequency rf discharge in a slab geometry. A maximum continuous wave cw output power­7 Until now the research in this wave- length region was concentrated mainly on the improvement of solid

  12. Density waves in Saturn's rings probed by radio and optical occultation - Observational tests of theory

    NASA Technical Reports Server (NTRS)

    Brophy, Thomas G.; Rosen, Paul A.

    1992-01-01

    A parallel examination is conducted of Voyager radio and photopolarimeter occultation observations of the Saturn A ring's density waves. The radio instrument waves exhibit an average -90 deg offset from the dynamical phase. A warping height of about 100-m amplitude can qualtitatively reproduce this phase shift, while preserving the overall model wave shape. These results may be profoundly relevant for satellite-ring torque calculations in Saturn's rings, given the deposition of all of the net torque of the standard model in the first wavelength.

  13. Ionospheric scintillation modeling for high- and mid-latitude using B-spline technique

    NASA Astrophysics Data System (ADS)

    Priyadarshi, S.

    2015-09-01

    Ionospheric scintillation is a significant component of space-weather studies and serves as an estimate for the level of perturbation in the satellite radio wave signal caused due to small-scale ionospheric irregularities. B-spline functions are used on the GPS ground based data collected during the year 2007-2012 for modeling high- and mid-latitude ionospheric scintillation. Proposed model is for Hornsund, Svalbard and Warsaw, Poland. The input data used in this model were recorded by GSV 4004b receivers. For validation, results of this model are compared with the observation and other existing models. Physical behavior of the ionospheric scintillation during different seasons and geomagnetic conditions are discussed well. Model is found in good coherence with the ionospheric scintillation theory as well as to the accepted scintillation mechanism for high- and mid-latitude.

  14. Wave propagation and earth satellite radio emission studies

    NASA Technical Reports Server (NTRS)

    Yeh, K. C.; Liu, C. H.; Flaherty, B. J.

    1974-01-01

    Radio propagation studies of the ionosphere using satellite radio beacons are described. The ionosphere is known as a dispersive, inhomogeneous, irregular and sometimes even nonlinear medium. After traversing through the ionosphere the radio signal bears signatures of these characteristics. A study of these signatures will be helpful in two areas: (1) It will assist in learning the behavior of the medium, in this case the ionosphere. (2) It will provide information of the kind of signal characteristics and statistics to be expected for communication and navigational satellite systems that use the similar geometry.

  15. Double layers and plasma-wave resistivity in extragalactic jets: Cavity formation and radio-wave emission

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.

    1987-01-01

    For estimated values of the currents carried by extragalactic jets, current-driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur. Strong plasma double layers, however, may exist within self-maintained density cavities, the relativistic double-layer-emitted electron, and ion beams driving plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  16. Double layers and plasma-wave resistivity in extragalactic jets - Cavity formation and radio-wave emission

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.

    1987-01-01

    Current driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur in extragalactic jets for estimated values of the carried currents. Strong plasma double layers, however, may exist within self-maintained density cavities. The relativistic double-layer-emitted electron and ion beams drive plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  17. The Response of a Two-Element Radio Interferometer to Gravitational Waves

    E-print Network

    Kipp Cannon

    2003-11-20

    This document presents a ray-optics analysis of the response of a two-element radio interferometer to the presence of a plane gravitational wave. A general expression for the differential phase observed between the two receiving stations as a result of an arbitrary gravitational wave is determined, as well as the specific responses to monochromatic and black hole ring-down waveforms. Finally, the possibility of gravitational wave detection via this mechanism is discussed in the context of interferometer noise.

  18. Reviving Fossil Radio Plasma in Clusters of Galaxies by Adiabatic Compression in Environmental Shock Waves

    E-print Network

    Torsten A. Ensslin; Gopal-Krishna

    2000-11-06

    We give for a plasma with a history of several expansion and contraction phases an analytical model of the evolution of a contained relativistic electron population under synchrotron, inverse Compton and adiabatic energy losses or gains. This is applied to different scenarios for evolution of radio plasma inside the cocoons of radio galaxies, after the activity of the central engine has ceased. It is demonstrated that fossil radio plasma with an age of even up to 2 Gyr can be revived by compression in a shock wave of large-scale structure formation, caused during the merging events of galaxy clusters, or by the accretion onto galaxy clusters. We argue, that this is a highly plausible explanation for the observed cluster radio relics, which are the regions of diffuse radio emission found in clusters of galaxies, without any likely parent radio galaxy seen nearby. An implication of this model is the existence of a population of diffuse, ultra-steep spectrum, very low frequency radio sources located inside and possibly outside of clusters of galaxies, tracing the revival of aged fossil radio plasma by the shock waves associated with large-scale structure formation.

  19. Ray-tracing Calculation of VHF Radio Waves Scattered by Field-aligned Irregularities Associated with Equatorial Plasma Bubbles

    NASA Astrophysics Data System (ADS)

    Nakata, Hiroyuki; Akaike, Yoshiaki; Otsuka, Yuichi; Takano, Toshiaki; Ujigawa, Satoshi; Nagashima, Ikuo

    In order to explain the propagation of VHF radio waves for TV broadcasting transmitted from Southeast Asia associated with equatorial plasma bubbles, we have examined ray paths of the radio waves scattered by field-aligned irregularities in equatorial plasma bubbles. In determining the ray paths of the radio waves, a ray tracing calculation combined with a model of the scattering by field-aligned irregularities is used. It is found that VHF radio waves transmitted from Philippines can propagate to Japan due to scattering by field-aligned irregularities located above the East China Sea.

  20. Verification of nonlinear particle simulation of radio frequency waves in tokamak

    NASA Astrophysics Data System (ADS)

    Kuley, A.; Lin, Z.; Bao, J.; Wei, X. S.; Xiao, Y.; Zhang, W.; Sun, G. Y.; Fisch, N. J.

    2015-10-01

    Nonlinear simulation model for radio frequency waves in fusion plasmas has been developed and verified using fully kinetic ion and drift kinetic electron. Ion cyclotron motion in the toroidal geometry is implemented using Boris push in the Boozer coordinates. Linear dispersion relation and nonlinear particle trapping are verified for the lower hybrid wave and ion Bernstein wave (IBW). Parametric decay instability is observed where a large amplitude pump wave decays into an IBW sideband and an ion cyclotron quasimode (ICQM). The ICQM induces an ion perpendicular heating, with a heating rate proportional to the pump wave intensity.

  1. Simultaneous observations of periodic non-Io decametric radio emission by ground radio telescope URAN-2 and STEREO/WAVES

    NASA Astrophysics Data System (ADS)

    Panchenko, M.; Brazhenko, A. I.; Rucker, H. O.; Frantzusenko, A.; Shaposhnikov, V. E.; Konovalenko, A. A.

    2013-09-01

    Periodic bursts of the non-Io component of Jovian decametric radio emission (non-Io DAM) is observed as (1) series of arc-like radio bursts with negative frequency drift which reoccur with 1.5% longer period than the Jovian magnetosphere rotation rate, (2) series of bursts with positive frequency drift which reoccur with Jupiter's rotation period and (3) periodic non-arc like radio features [1, 2]. These bursts are typically detected during several Jupiter rotations in decametric frequency range from 4 MHz to 12 - 16 MHz between 300° and 60° of CML. We present simultaneous observations of the periodic non-Io controlled DAM performed by the WAVES radio experiment onboard the two STEREO spacecraft and the groundbased radio telescope URAN-2 (Poltava, Ukraine) operated in the decametric frequency range. URAN-2 with an effective area of about 30000 m2 consists of 512 broadband crossed dipoles and equipped with the high performance digital radio spectrometer with polarization measurement capability. During the observation campaign Sep., 2012 - Apr., 2013 URAN-2 recorded a large amount of Jovian DAM events with the high time-frequency resolution (4 kHz - 100 ms) in a frequency range 8-32 MHz. In the same time the two spatially separated STEREO spacecraft was able to observe DAM in the frequency range up to 16 MHz. The first analysis of the acquired stereoscopic observations is presented. In particular, we show one episode when the periodic non-arc DAM was recorded together with long lasting Jovian narrow band (NB) emissions. These NB emission was observed at the high frequency cutoff of DAM and can be interpreted as propagation of the decametric radiation in the Jovian ionosphere [3]. We discuss the possible relations between the observed NB events and the periodic non-Io controlled Jovian decametric radio emission.

  2. Scintillation Monitoring Using Asymmetry Index

    NASA Astrophysics Data System (ADS)

    Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

    Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric station in Cairo, Egypt (lat= 29.8641 °, long= 31.3172 °). It was observed that the level of asymmetry was significantly increased during the main phase of the geomagnetic storm. This was due to the changes in ionization, which in turn produced large gradients along occulted ray path in the ionosphere. A very good correlation was found between the evaluated ionospheric asymmetry index and the S4 scintillation index. Additionally, the correlation between evaluated ionospheric asymmetry and errors related to the RO inversion products such as peak electron density (delta NmF2) and Vertical TEC (delta VTEC) estimates also showed promising results. This work is carried out under the framework of the TRANSMIT project (Training Research and Applications Network to Support the Mitigation of Ionospheric Threats - www.transmit-ionosphere.net). [1]Basu Sa. and Basu Su., (1981), ‘Equatorial Scintillation - A Review’, Journal of Atmospheric and Solar-Terrestrial Physics, 43, p. 473. [2]Davies K., (1990), ‘Ionospheric Radio’, IEEE Electromagnetic Waves Series 31, Peter Peregrinus Ltd. [3]Spencer, P., Mitchell, C.N., (2007) ‘Imaging of fast moving electron-density structures in the polar cap’, Annals of Geophysics, vol. 50, no. 3, pp. 427-434. [4]Shaikh, M.M., Notarpietro, R., Nava, B., (2013) ‘The Impact of Spherical Symmetry Assumption on Radio Occultation Data Inversion in the Ionosphere: An Assessment Study’, Advances in Space Research, doi: http://dx.doi.org/10.1016/j.asr.2013.10.025.

  3. In-flight calibration of the Cassini-Radio and Plasma Wave Science (RPWS) antenna system for direction-finding and

    E-print Network

    Gurnett, Donald A.

    In-flight calibration of the Cassini-Radio and Plasma Wave Science (RPWS) antenna system) as well as atmospheric (lightning) origin. The Radio and Plasma Wave Science (RPWS) experiment is designed to measure the full polarization and the wave vector of the incoming radio waves, allowing us to retrieve

  4. The influence of polarization on millimeter wave propagation through rain. [radio signals

    NASA Technical Reports Server (NTRS)

    Bostian, C. W.; Stutzman, W. L.; Wiley, P. H.; Marshall, R. E.

    1973-01-01

    The measurement and analysis of the depolarization and attenuation that occur when millimeter wave radio signals propagate through rain are described. Progress was made in three major areas: the processing of recorded 1972 data, acquisition and processing of a large amount of 1973 data, and the development of a new theoretical model to predict rain cross polarization and attenuation. Each of these topics is described in detail along with radio frequency system design for cross polarization measurements.

  5. Variation of Langmuir wave polarization with electron beam speed in type III radio bursts

    SciTech Connect

    Malaspina, David M.; Cairns, Iver H.; Ergun, Robert E.

    2013-06-13

    Observations by the twin STEREO spacecraft of in-situ electric field waveforms and radio signatures associated with type III radio bursts have demonstrated that the polarization of electron beam-driven waves near the local plasma frequency depends strongly on the speed of the driving electron beam. We expand upon a previous study by including all radio bursts with in-situ waveforms observed by STEREO in 2011. The expanded data set contains five times more radio bursts (35 up from 7) and three times as many Langmuir waves (663 up from 168). While this expanded study supports the results of the original study, that faster (slower) beam electrons drive waves with strong (weak) electric fields perpendicular to the local magnetic field, the larger data set emphasizes that the observation of strong perpendicular electric fields at high electron beam speeds is probabilistic rather than definite. This property supports the interpretation of wave polarization dependence on beam speed as Langmuir/z-mode waves shifted to small wave number through interaction with turbulent solar wind density fluctuations.

  6. Analysis of the Temporal Structural Function of Tropospheric Delay of Radio Waves Using Radio Measurements of the Signals from Global Navigation Satellite Systems

    NASA Astrophysics Data System (ADS)

    Khutorov, V. E.; Teptin, G. M.

    2014-11-01

    We present the results of a three-year experimental study of propagation of decimeter radio waves in the troposphere. The time analysis of the structural function of tropospheric delay of the decimeter radio waves for the three-year measurements of the GLONASS and GPS signals in a city of Kazan is given. The tropospheric contribution to the variance of the decimeter radio-wave delay is for the first time observed to significantly differ for the variations with time scales 1 to 24 h.

  7. Radio wave dissipation in turbulent auroral plasma during the precipitation of energetic electrons

    SciTech Connect

    Mishin, E.V.; Luk'ianova, L.N.; Makarenko, S.F.; Atamaniuk, B.M. Polish Academy of Sciences, Institute of Fundamental Technological Research, Warsaw )

    1992-04-01

    The results of the theoretical analysis of anomalous (collisionless) radio wave absorption in the turbulent auroral ionosphere during the intrusion of energetic electrons (i.e., in aurorae) are presented. The implications of the plasma turbulent layer (PTL) theory are used. It is shown that the dissipation of radio waves with frequencies much higher than the plasma frequency is caused by the nonlinear (combined) scattering in turbulent plasma of the PTL. In the auroral electrojet layer the principal dissipative process for the radio waves with frequencies close to the plasma frequency is O-Z transformation on the field-aligned, small-scale density fluctuations. The typical dissipation decrements are estimated. 26 refs.

  8. Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies

    E-print Network

    Torsten A. Ensslin; Patrick Simon; Peter L. Biermann; Ulrich Klein; Sven Kohle; Philipp P. Kronberg; Karl-Heinz Mack

    2000-12-19

    Sensitive images of low-level, Mpc-sized radio cocoons offer new opportunities to probe large scale intergalactic gas flows outside clusters of galaxies. New radio images of high surface brightness sensitivity at strategically chosen wavelengths of the giant radio galaxy NGC 315 (Mack et al. 1997,1998) reveal significant asymmetries and particularities in the morphology, radio spectrum and polarization of the ejected radio plasma. We argue that the combination of these signatures provides a sensitive probe of an environmental shock wave. Analysis of optical redshifts in NGC 315 vicinity confirms its location to be near, or at a site of large-scale flow collisions in the 100 Mpc sized Pisces-Perseus Supercluster region. NGC 315 resides at the intersection of several galaxy filaments, and its radio plasma serves there as a `weather station' (Burns 1998) probing the flow of the elusive and previously invisible IGM gas. If our interpretation is correct, this is the first indication for a shock wave in flows caused by the cosmological large scale structure formation, which is located in a filament of galaxies. The possibility that the putative shock wave is a source of gamma-rays and ultra high energy cosmic rays is briefly discussed.

  9. The peculiarities of long-wave radio bursts during the proton events observed on Interball-1

    NASA Astrophysics Data System (ADS)

    Valentina, Prokudina

    We analyzed the radio bursts at frequency range 1980 - 100 kHz which were registered by AKR-X (Interball-1) during proton events (SEP). As a rule, we observed radio bursts of III type with large amplitude. The onset of the burst coincided with the explosive (flash) phase of power flare, as we may judge from the comparison of the maximum of the microwave and HXR burst with temporal profile of long-wave radio burst. Accelerated protons escape from the flare without delay and arrived to the Earth during 20-40 min.

  10. Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

    SciTech Connect

    Norin, L.; Leyser, T. B.; Nordblad, E.; Thide, B.; McCarrick, M.

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  11. Relations among low ionosphere parameters and high frequency radio wave absorption

    NASA Technical Reports Server (NTRS)

    Cipriano, J. P.

    1973-01-01

    Charged particle conductivities measured in the very low ionosphere at White Sands Missile Range, New Mexico, and Wallops Island, Virginia, are compared with atmospheric parameters and high frequency radio wave absorption measurements. Charged particle densities are derived from the conductivity data. Between 33 and 58 km, positive conductivity correlated well with neutral atmospheric temperature, with temperature coefficients as large as 4.6%/deg K. Good correlations were also found between HF radio wave absorption and negative conductivity at altitudes as low as 53 km, indicating that the day-to-day absorption variations were principally due to variations in electron loss rate.

  12. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    PubMed

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA. PMID:19257596

  13. Scattering of radio frequency waves by edge density blobs in tokamaks

    NASA Astrophysics Data System (ADS)

    Ram, A. K.; Hizanidis, K.; Kominis, Y.

    2012-03-01

    The density blobs and fluctuations present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction and diffraction. A previous study has considered refractive scattering using the geometric optics approximation [1]. It is found that the scattering can diffuse rays in configuration 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 profile. The geometric optics approximation is of limited validity. We have developed a full-wave, cold plasma, model for wave scattering in which the size and density of the blobs are arbitrary. The model allows for diffractive scattering of waves as well as coupling of the incident wave to other plasma waves. Diffractive scattering can lead to ``shadowing'' while the coupling to other plasma waves can broaden the spectrum of the incident wave, and reduce the power propagating into the interior of the plasma. The full-wave model and the consequences of diffractive scattering of RF waves by blobs will be discussed. [4pt] [1] K. Hizanidis, A.K. Ram, Y. Kominis, and C. Tsironis, Phys. Plasmas 17, 022505 (2010).

  14. Radio Wave Generation by a Collision or Contact between Various Materials

    NASA Astrophysics Data System (ADS)

    Takano, T.; Hanawa, R.; Saegusa, K.; Ikeda, H.

    2014-12-01

    In fracture of rock, radio wave emission was found experimentally [1]. This phenomenon could be used to detect a rock fracture during an earthquake or a volcanic activity [2]. The cause of the radio wave is expected to be micro-discharges, which are generated by an inhomogeneous potential distribution around micro-cracks. In order to better understand the phenomena and clarify the cause of radio wave emission, we carried out experiments to detect the emission in the cases of a collision or contact between various materials. We used receiving systems with great sensitivities and sufficient frequency bandwidths at 1 MHz-, 300 MHz-, 2 GHz-, and 18 GHz-bands. The specimen materials are as follows: Steel (2) Brass (3) Copper (4)Small coin (5)Celluloid. We obtained the following results: The signal was detected for the specimen of (1) to (4), but not for (5). The signal is composed of intermittent spikes which include waves with a frequency close to the center frequency of each frequency band. The power is strongest at the lower frequencies among all frequency bands. The more details will be given in the presentation. The origin of radio wave emission from the metal is supposed to be discharges between materials in these experiments. It is surprising that even a small coin can generate a significant amount of radio wave. Accordingly, it is inferred that all amount of charges are discharged through a conductive metal. On the other hand, celluloid did not generate radio wave, though the specimen was sufficiently charged by brushing. It is inferred that a quite localized charge was discharged but the remaining charges were blocked due to poor conductivity. Extending this hypothesis, large-scale contact should have occurred between broken fragments for the radio wave generation in the aforementioned rock fracture experiments. Turbulence of the fragments is a candidate for the explanation. [1] K. Maki et al., "An experimental study of microwave emission from compression failure of rocks" (in Japanese), Jour. of the Seismological Society of Japan, vol.58, no.4, pp.375-384, 2006.[2] T. Takano al., "Detection of microwave emission due to rock fracture as a new tool for geophysics: A field test at a volcano in Miyake Island, Japan", Journal of Applied Geophysics, 94, pp.1-14, 2013.

  15. A simple demonstration for exploring the radio waves generated by a mobile phone

    NASA Astrophysics Data System (ADS)

    Hare, Jonathan

    2010-09-01

    Described is a simple low cost home-made device that converts the radio wave energy from a mobile phone signal into electricity for lighting an LED. No battery or complex circuitry is required. The device can form the basis of a range of interesting experiments on the physics and technology of mobile phones.

  16. A Simple Demonstration for Exploring the Radio Waves Generated by a Mobile Phone

    ERIC Educational Resources Information Center

    Hare, Jonathan

    2010-01-01

    Described is a simple low cost home-made device that converts the radio wave energy from a mobile phone signal into electricity for lighting an LED. No battery or complex circuitry is required. The device can form the basis of a range of interesting experiments on the physics and technology of mobile phones. (Contains 5 figures.)

  17. Non-contact prediction of soil moisture profiles using radio wave reflection

    NASA Astrophysics Data System (ADS)

    Needham, Duane Lee

    Scope and method of study. This study investigated the potential of non-contact measurement of volumetric soil moisture profiles by detecting reflected VHF and UHF radio waves. The investigation included a variability analysis of the dielectric properties of soil, tests to relate volumetric moisture content to dielectric properties, a simulation of radio wave reflection from various profiles, and field trials in which antennas transmitted and received radio waves for detection of the moisture gradient in the soil directly below the instrument. In addition to the measurements, an algorithm was devised to resolve layers of moisture from radio wave reflections of multiple frequencies. Potential applications for such an instrument may include irrigation scheduling, detection of plant stress, and hydrological research. Findings and conclusions. The model that simulated reflection coefficients in the frequency range of 80 MHz to 1 GHz was tested using hypothetical and existent moisture profiles. Results of simulated profiles indicated that reflection coefficients could be used to distinguish between volumetric surface moisture and could detect subsurface moisture to a depth of 45.7 cm. Reflection measurements made in the field trials indicated that linear correlation could be made with volumetric moisture in the top 15.2 cm. The profile restoration algorithm closely predicted simulated surface moisture but had a high failure rate predicting subsurface moisture. Results of the study indicated that reflection coefficients could be used to detect soil moisture at depth, but the restoration algorithm did not effectively resolve moisture layers.

  18. EFFECTS OF RADIO WAVE PROPAGATION IN URBANIZED AREAS ON UAV-GCS COMMAND AND CONTROL

    E-print Network

    Jenn, David C.

    EFFECTS OF RADIO WAVE PROPAGATION IN URBANIZED AREAS ON UAV-GCS COMMAND AND CONTROL Lock Wai Lek In an urban environment, the linkage between UAVs and ground control stations are subjected to multipath multipath can result in a nearly complete loss of command signals, which can limit the UAV's operational

  19. Radio wave emitted by an extensive air showers in 10KHz to 1MHz region

    NASA Technical Reports Server (NTRS)

    Nichimura, J.

    1985-01-01

    The importance of radio waves in a frequency range of less than 1MHz in an EAS shower is discussed. Estimates of radio intensities at 10KHz, 100KHz and 1MHz in EAS showers made on the basis of the Kahn-Lerche theory. Negative charge excess in a shower is the main source of low frequency radio emission, in spite of the importance of the contribution of transverse current in the geomagnetic field in a higher frequency range. An estimate is also made for radio intensity produced when the shower hits the ground. The contribution of this process seems to be important at a large distance, i.e., beyond 1km from the shower axis.

  20. Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Haspodarsky, G. B.; Persoon, A. M.; Averkamp, T. F.; Cecconi, B.; Lecacheux, A.; Zarka, P.; Canu, P.; Cornilleau-Wehrlin, N.

    2005-01-01

    We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 k 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.

  1. Radio-wave emission due to hypervelocity impacts and its correlation with optical observations

    NASA Astrophysics Data System (ADS)

    Takano, T.; Maki, K.; Yamori, A.

    This paper describes the most interesting phenomena of radio-wave emission due to hypervelocity impacts. A projectile of polycarbonate with 1.1 g weight was accelerated by a rail gun to 3.8 km/sec, and hit two targets which are a 2 mm thick aluminum plate upstream and a 45 mm diameter aluminum column downstream, respectively. The projectile first breaks wires to give a triggering signal to a data recorder, then penetrates the aluminum plate, and finally hit the column, The emitted radio-waves propagate through the chamber window, and are received by antennas at each frequency band. The receivers in 22 GHz- and 2 GHz-bands consist of a low noise amplifier, a mixer, a local oscillator and an IF amplifier , respectively. The receiver in 1 MHz-band is a simple RF amplifier. The outputs of all receivers are fed to a data recorder which is actually a high-speed digital oscilloscope with a large amount of memory. The radio-waves were successfully recorded in 22 GHz-band with 500 MHz bandwidth, in 2 GHz-band with 300 MHz bandwidth, and in 1MHz-band. The waveforms in 22 GHz- and 2 GHz-bands coincide well each other, and are composed of two groups of sharp impulses with a separation of about 20 micro seconds. The width of an impulse is less than 2 n sec. which is the resolution limit of the data recorder. We carried out optical observations using an ultra-high speed camera simultaneously through another window of the chamber. The time interval between scenes is 2 micro sec. We can see a faint light of the projectile before the first impact to the plate, and then a brilliant gas exploding backward from the plate and forward to the column. After hitting the column target, the brilliant gas flows to the chamber wall and is reflected back to make a mixture with dark gas in the chamber. Excellent correlation between radio-wave emission and the observed optical phenomena was obtained in the experiment. It is easily conceived that the radio-waves consist of quite a wide frequency spectrum because of the spiky waveforms. The emission of the radio-waves is delayed from the optical events by several micro seconds. The optical phenomena are said to be mostly attributed to Bremstrahlung. The radio-wave phenomena are esteemed to be partially due to Bremstrahlung, but mainly due to other causes such as the heating effects of the targets or energy release from broken lattices of the targets.

  2. FIPS 1402 NonProprietary Security Policy: Persistent Systems Wave Relay Quad Radio Router and Man Portable Unit (Generation 2, Generation 3 Single/Dual, and Generation 4)

    E-print Network

    FIPS 1402 NonProprietary Security Policy: Persistent Systems Wave Relay Quad Radio Router and Man Wave Relay Quad Radio Router and Man Portable Unit (Generation 2, Generation 3 Single;FIPS 1402 NonProprietary Security Policy: Persistent Systems Wave Relay Quad Radio Router and Man

  3. IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 2, FEBRUARY 2006 929 A Novel Millimeter-Wave-Band Radio-Over-Fiber

    E-print Network

    Yao, Jianping

    Millimeter-Wave-Band Radio-Over-Fiber System With Dense Wavelength-Division Multiplexing Bus Architecture Kashyap Abstract--In this paper, we propose a novel millimeter-wave- band radio-over-fiber (RoF) system, millimeter-wave communi- cations, optical fiber communications, radio-over-fiber (RoF), subcarrier modulation

  4. FIPS 1402 NonProprietary Security Policy: Persistent Systems Wave Relay Single, Dual, and Quad Radio Document Version 5.2 Persistent Systems Page 1 of 21

    E-print Network

    Proprietary Security Policy Persistent Systems Wave Relay Single, Dual, and Quad Radio Board Level 1Proprietary Security Policy: Persistent Systems Wave Relay Single, Dual, and Quad Radio Board Document Version 5 Policy for the Wave Relay Single, Dual, and Quad Radio Board. #12;FIPS 1402 NonProprietary Security

  5. Combined evidence for four- and three-wave interactions in solar type III radio bursts

    NASA Astrophysics Data System (ADS)

    Golla, T.; MacDowall, R. J.

    2013-12-01

    The high time resolution observations obtained by the STEREO/WAVES experiment show that in solar type III radio bursts, Langmuir waves often occur as intense one-dimensional or three-dimensional wave packets. We present the observations of one of the 1d wave packets as well as one of the 3d wave packets, whose short durations and peak intensities satisfy the threshold conditions for the oscillating two-stream instability (OTSI) and formation of collapsing envelope solitons. The depths, widths and temporal coincidences of the density cavities, observed during these wave packets indicate that they probably correspond to cavitons, generated by the ponderomotive force of the collapsing wave packets. The spectrum of each of the parallel and perpendicular components of the 3d wave packet as well as the spectrum of the parallel component of the 1d wave packet show similar characteristics, namely, each of them contains a primary peak at fpe, two secondary peaks at fpe×fS and a low-frequency enhancement below fS, which, as indicated by the frequency and wave number resonance conditions, and the fast Fourier transform (FFT)-based tricoherence spectral peak at (fpe, fpe, fpe+fS, fpe- fS) are coupled to each other by the OTSI type of four-wave interaction (fpe is the local electron plasma frequency and fS is the frequency of ion sound waves). In addition to the primary peak at fpe, each of these spectra also contains a peak at 2fpe, which as indicated by the frequency and wave number resonance conditions, and the waveletbased bicoherence spectral peak at (fpe, fpe), appears to correspond to the second harmonic electromagnetic waves generated as a result of coalescence of oppositely propagating sidebands excited by the OTSI. Additionally, the spectrum of the 1d wave packet also contains a peak at 3fpe, which as indicated by the bispectral analysis probably corresponds to electromagnetic waves excited as a result of merging of Langmuir waves with second harmonic electromagnetic waves. Thus, these observations for the first time provide combined evidence that (1) the OTSI and related strong turbulence processes play a significant role in the stabilization of the electron beam, (2) the coalescence of the oppositely propagating up- and down-shifted daughter Langmuir waves excited by the OTSI probably is the emission mechanism of the second harmonic radiation, and (3) the Langmuir collapse follows the route of OTSI in some of the type III radio bursts.

  6. Radio wave propagation experiments to probe the ionosphere

    NASA Technical Reports Server (NTRS)

    Schmid, P. E.

    1972-01-01

    Ionospheric bias corrections associated with radio tracking of spacecraft depend on the following measuring techniques for integrated electron content: (1) Faraday rotation measurements from an earth synchronous satellite; (2) ranging measurements at two frequencies; and (3) group and phase velocity measurements obtained from tracking data. The extraction of the integrated electron content directly from tracking data is achieved by comparison of range-rate measurements based on Doppler shift with differentiated range measurements based on tone delay. This method is most desirable because the measured corrections pertain directly to the spacecraft whose orbit is being determined and can be used in near earth as well as deep space tracking data.

  7. Kilometric radio waves generated along auroral field lines observed by ground facilities - A theoretical model

    NASA Technical Reports Server (NTRS)

    Ziebell, L. F.; Wu, C. S.; Yoon, Peter H.

    1991-01-01

    A theory of generation of radio waves observed by ground-based facilities in the frequency range 150-700 kHz is discussed. This work is a continuation of an earlier discussion (Wu et al., 1989) in which it was proposed that the trapped electrons along the auroral field lines can lead to a cyclotron instability which amplifies the whistler waves observed at ground level. The objective of the present study is to investigate the propagation effect on the wave amplification and to examine whether the proposed mechanism is indeed viable.

  8. Inconsistency of Ulysses Millisecond Langmuir Spikes with Wave Collapse in Type 3 Radio Sources

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Robinson, P. A.

    1995-01-01

    Recent Ulysses observations of millisecond spikes superposed on broader Langmuir wave packets in type 3 radio sources are compared quantitatively with constraints from the theory of wave collapse. It is found that both the millisecond spikes and the wave packets have fields at least 10 times too small to be consistent with collapse, contrary to previous interpretations in terms of this process. Several alternative explanations are considered and it is argued that the spikes should be interpreted as either non-collapse phenomena or observational artifacts. To the extent the observations are representative, this rules out theories for type 3 bursts at approx. 1 - 4 AU that rely on collapse.

  9. NONLINEAR WAVE INTERACTIONS AS EMISSION PROCESS OF TYPE II RADIO BURSTS

    SciTech Connect

    Ganse, Urs; Kilian, Patrick; Spanier, Felix; Vainio, Rami

    2012-06-01

    The emission of fundamental and harmonic frequency radio waves of type II radio bursts are assumed to be products of three-wave interaction processes of beam-excited Langmuir waves. Using a particle-in-cell code, we have performed simulations of the assumed emission region, a coronal mass ejection foreshock with two counterstreaming electron beams. Analysis of wavemodes within the simulation shows self-consistent excitation of beam-driven modes, which yield interaction products at both fundamental and harmonic emission frequencies. Through variation of the beam strength, we have investigated the dependence of energy transfer into electrostatic and electromagnetic modes, confirming the quadratic dependence of electromagnetic emission on electron beam strength.

  10. Cluster Radio Relics as a Tracer of Shock Waves of the Large-Scale Structure Formation

    E-print Network

    Torsten A. Ensslin; Peter L. Biermann; Ulrich Klein; Sven Kohle

    1997-12-22

    We present evidence for the existence of shock waves caused by the formation of the large-scale structure. In some clusters of galaxies peripherally located sources of extended diffuse radio emission exist, the so-called cluster radio relics. They have steep radio spectra but no apparent cutoff, as old remnants of radio galaxies usually have. Therefore particle acceleration has to take place within them. We propose that shock structures of the cosmological large-scale matter flows are responsible for the acceleration of relativistic electrons: cluster accretion shocks and bow shocks of merger events. We develop a theory of radio plasma having traversed these shocks and compare it to observational data of nine radio relics (0038-096, 0917+75, 1140+203, 1253+275, 1712+64, 1706+78, 2006-56, 2010-57, 1401-33) and their host clusters (A85, A786, A1367, Coma, A2255, A2256, A3667, S753). The necessary accretion power, the spectral index of the radio spectrum, the acceleration efficiency of the shock, the diffusion coefficient in the post-shock region, and the predicted radio polarization in all of our examples fit into a coherent interpretation of the observational data. Since polarization measurements are available only for four sources, the predictions of our theory can be independently checked using other examples. The predicted values of the shock compression ratio, density and temperature of the infalling gas, magnetic field strength of the shocked and unshocked radio plasma are discussed within the frame of structure formation theory.

  11. The seasonal variation of the D region as inferred from propagation characteristics of LF radio waves

    NASA Technical Reports Server (NTRS)

    Ishimine, T.; Ishii, T.; Echizenya, Y.

    1985-01-01

    The propagation data of JG2AS 40 kHz (Japanese Standard Frequency), Loran C 100 kHz radio waves, and meteorological data were analyzed to study the association of propagation characteristics of LF radio waves with the atmospheric circulation in the mesosphere. The monthly averaged electric fields were depicted on the complex plane for typical summer and winter months, June and November. The locus traced out by the electric field vector during daytime is nearly circular. This is because during daytime the amplitude of the sky wave remains nearly constant while its phase changes in accord with the height change of the reflection layer, and thus the electric field vector traces out a circular locus with its center at the tip of the supposed ground wave vector. The locus has a loop during the sunrise or sunset period, which seems to arise from interference of two waves reflected by two different layers. In June the amplitude of the sky wave decreases rapidly before the dawn or increases after the dusk. In November such rapid change is not observed. During nighttime, the sky wave phase changes in such a way as to suggest that the reflection height moves upwards with time before midnight or lowers after midnight in November. In June it changes similarly before midnight, but after midnight it varies erratically. These characteristics are closely related to the structure of the D region, which is clearly shown by simulating the loci traced out by electric fields.

  12. Reflection of radio waves by sporadic-E layers

    NASA Technical Reports Server (NTRS)

    Miller, K. L.; Smith, L. G.

    1977-01-01

    A full-wave analysis of the reflection coefficient is developed and applied to electron-density profiles of midlatitude sporadic-E layers observed by rocket-borne probes. It is shown that partial reflection from the large electron-density gradients at the upper and lower boundaries of sporadic-E layers does not account for the partial transparency observed by ionosondes.

  13. Thin film scintillators

    NASA Astrophysics Data System (ADS)

    McDonald, Warren; McKinney, George; Tzolov, Marian

    2015-03-01

    Scintillating materials convert energy flux (particles or electromagnetic waves) into light with spectral characteristic matching a subsequent light detector. Commercial scintillators such as yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) are commonly used. These are inefficient at lower energies due to the conductive coating present on their top surface, which is needed to avoid charging. We hypothesize that nano-structured thin film scintillators will outperform the commercial scintillators at low electron energies. We have developed alternative thin film scintillators, zinc tungstate and zinc oxide, which show promise for higher sensitivity to lower energy electrons since they are inherently conductive. Zinc tungstate films exhibit photoluminescence quantum efficiency of 74%. Cathodoluminescence spectroscopy was applied in transmission and reflection geometries. The comparison between the thin films and the YAG and YAP commercial scintillators shows much higher light output from the zinc tungstate and zinc oxide at electron energies less than 5 keV. Our films were integrated in a backscattered electron detector. This detector delivers better images than an identical detector with commercial YAG scintillator at low electron energies. Dr. Nicholas Barbi from PulseTor LLC, Dr. Anura Goonewardene, NSF Grants: #0806660, #1058829, #0923047.

  14. Newly Discovered Parametric Instabilities Excited by High Power Radio Waves in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, Paul

    2010-11-01

    A powerful electromagnetic wave can decay into a large number of low frequency electrostatic waves and a scattered electromagnetic wave by generalized stimulated Brillouin scatter (GSBS). The generalization occurs in the F-layer ionosphere because of the presence of the magnetic field supporting a large number of plasma waves not present in an unmagnetized plasma. Stimulated Brillouin scatter excites the ion acoustic mode. In addition, GSBS can excite slow MHD, Alfven, fast MHD, ion cyclotron, whistler, lower hybrid, ion Bernstein waves. The first detection of this process during ionospheric modification with high power radio waves was demonstrated using the HAARP transmitter in Alaska in 2009. Subsequent experiments have provided additional verification of the GSBS process with quantitative measurements of the scattered electromagnetic waves with low frequency offsets from the pump wave. Relative to ground-based laboratory experiments with laser plasma interactions, the ionospheric HF wave interactions experiments are more completely diagnosed into terms of understanding the basic decay process of the magnetized plasma. Applications of the GSBS observations included remote sensing of the plasma state and launching propagating wave modes.

  15. Determining the solar wind speed above active regions using remote radio-wave observations

    NASA Technical Reports Server (NTRS)

    Fainberg, J.; Stone, R. G.; Bougeret, J.-L.

    1983-01-01

    A new technique has made it possible to measure the velocity of portions of the solar wind during its flow outward from the sun. This analysis utilizes spacecraft (ISEE-3) observations of radio emission generated in regions of the solar wind associated with solar active regions. By tracking the source of these radio waves over periods of days, it is possible to measure the motion of the emission regions. Evidence of solar wind acceleration during this outward flow, consistent with theoretical models, has also been obtained.

  16. Observational evidence for the collapsing Langmuir wave packet in a solar type III radio burst

    NASA Astrophysics Data System (ADS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2013-07-01

    High time resolution observations from the STEREO spacecraft show that in solar type III radio bursts, Langmuir waves often occur as very intense one-dimensional magnetic field aligned field structures. One of these events represents the most intense Langmuir wave packet with WLneTe~7.2×10-3 ever detected in a type III radio burst until now (WL is the peak energy density, and ne and Te are the electron density and temperature, respectively). The detailed analysis of this wave packet indicates that (1) its peak intensity is well above the threshold for the oscillating two-stream instability (OTSI) and supersonic collapse; (2) its peak intensity and spatial scale satisfy the criterion for it to be a collapsing envelope soliton; (3) its low-frequency components provide evidence for a density cavity, whose depth, width, and temporal coincidence indicate that probably it is the ponderomotive force generated density cavity; and (4) its spectrum contains harmonic peaks at 2fpe and 3fpe (in addition to the main Langmuir wave peak at the electron plasma frequency, fpe), which, as indicated by the bispectral analysis, probably are of the electromagnetic waves generated as a result of coalescence of two oppositely propagating Langmuir waves, and a Langmuir wave and a second harmonic electromagnetic wave, respectively. These characteristics strongly suggest that this wave packet and its associated density cavity represent the collapsing envelope soliton-caviton pair formed as a result of OTSI, and in the present case, the strong turbulence processes probably play key roles in the beam stabilization as well as conversion of Langmuir waves into escaping radiation at 2fpe and 3fpe.

  17. Artificial airglow excited by high-power radio waves.

    PubMed

    Bernhardt, P A; Duncan, L M; Tepley, C A

    1988-11-18

    High-power electromagnetic waves beamed into the ionosphere from ground-based transmitters illuminate the night sky with enhanced airglow. The recent development of a new intensified, charge coupled-device imager made it possible to record optical emissions during ionospheric heating. Clouds of enhanced airglow are associated with large-scale plasma density cavities that are generated by the heater beam. Trapping and focusing of electromagnetic waves in these cavities produces accelerated electrons that collisionally excite oxygen atoms, which emit light at visible wavelengths. Convection of plasma across magnetic field lines is the primary source for horizontal motion of the cavities and the airglow enhancements. During ionospheric heating experiments, quasi-cyclic formation, convection, dissipation and reappearance of the cavites comprise a major source of long-term variability in plasma densities during ionospheric heating experiments. PMID:17834046

  18. Nonlinear nonresonant forces by radio-frequency waves in plasmas

    SciTech Connect

    Gao Zhe; Fisch, Nathaniel J.; Qin, Hong; Myra, J. R.

    2007-08-15

    Nonresonant forces by applied rf waves in plasmas are analyzed. Along the background dc magnetic field, the force arises from the gradient of the ponderomotive potential. Only when the dc magnetic field is straight, however, is this parallel force completely consistent with that from the single particle picture, where the ponderomotive force depends on the gradients of rf fields only. Across the dc magnetic field, besides the ponderomotive force from the particle picture, additional Reynolds stress and polarization stress contribute to the total force. For waves with frequency much lower than the cyclotron frequency, the perpendicular forces from the particle and fluid pictures can have opposite signs. In plasmas with a symmetry angle (e.g., toroidal systems), nonresonant forces cannot drive net flow or current in the flux surface, but the radial force may influence macroscopic behavior of plasma. Moreover, nonresonant forces may drive flow or current in linear plasmas or in a localized region of toroidal plasmas.

  19. Radio Wave 'Messengers' of Periodic Gravitational Radiation and the Problem of Gravitationally Induced Nonlinearity in Electrodynamic Systems

    E-print Network

    A. B. Balakin; Z. G. Murzakhanov; G. V. Kisun'ko

    2005-11-10

    We discuss a gravitationally induced nonlinearity in hierarchic systems. We consider the generation of extremely low-frequency radio waves with a frequency of the periodic gravitational radiation; the generation is due to an induced nonlinear self-action of electromagnetic radiation in the vicinity of the gravitational-radiation source. These radio waves are a fundamentally new type of response of an electrodynamic system to gravitational radiation. That is why we here use an unconventional term: radio-wave messengers of periodic gravitational radiation.

  20. Nonlinear nonresonant forces by radio-frequency waves in plasmas Department of Engineering Physics, Tsinghua University, Beijing 100084, China

    E-print Network

    Nonlinear nonresonant forces by radio-frequency waves in plasmas Zhe Gao Department of Engineering August 2007 Nonresonant forces by applied rf waves in plasmas are analyzed. Along the background dc and polarization stress contribute to the total force. For waves with frequency much lower than the cyclotron

  1. Detection of collapsing Langmuir wave packets in solar type III radio bursts

    NASA Astrophysics Data System (ADS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2013-06-01

    We report the STEREO/WAVES high time resolution observations of an intense Langmuir wave packet associated with a solar type III radio burst. The transformation of the electric field measurements from the spacecraft into magnetic field aligned coordinate system indicates that this is a field aligned one-dimensional structure. The peak intensity and short duration of this wave packet well satisfy the criterion for it to be the collapsing envelope soliton trapped in a self-generated density cavity. The spectrum of this 1D wave packet consists of an intense peak and two sidebands, corresponding to beam-resonant Langmuir waves, and down- and up-shifted daughter Langmuir waves, respectively, and an ion sound associated low-frequency enhancement. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the four wave interaction, called the oscillating two stream instability (OTSI). Furthermore, trispectral analysis indicates that these spectral components are coupled to each other with a high degree of phase coherency (high tricoherence). These findings provide a strong indication that the observed wave packet is a collapsing Langmuir envelope soliton formed as a result of OTSI.

  2. Experimental Probes of Radio Wave Propagation near Dielectric Boundaries and Implications for Neutrino Detection

    E-print Network

    Alvarez, R; Hanson, J C; Johannesen, A M; Macy, J; Prohira, S; Stockham, J; Stockham, M; Zheng, Al; Zheng, Am

    2015-01-01

    Experimental efforts to measure neutrinos by radio-frequency (RF) signals resulting from neutrino interactions in-ice have intensified over the last decade. Recent calculations indicate that one may dramatically improve the sensitivity of ultra-high energy ("UHE"; >EeV) neutrino experiments via detection of radio waves trapped along the air-ice surface. Detectors designed to observe the "Askaryan effect" currently search for RF electromagnetic pulses propagating through bulk ice, and could therefore gain sensitivity if signals are confined to the ice-air boundary. To test the feasibilty of this scenario, measurements of the complex radio-frequency properties of several air-dielectric interfaces were performed for a variety of materials. Two-dimensional surfaces of granulated fused silica (sand), both in the lab as well as occurring naturally, water doped with varying concentrations of salt, natural rock salt formations, granulated salt and ice itself were studied, both in North America and also Antarctica. In...

  3. Non-Gaussian Radio-Wave Scattering in the Interstellar Medium

    E-print Network

    Stanislav Boldyrev; Arieh Konigl

    2006-02-05

    It was recently suggested by Boldyrev & Gwinn that the characteristics of radio scintillations from distant pulsars are best understood if the interstellar electron-density fluctuations that cause the time broadening of the radio pulses obey non-Gaussian statistics. In this picture the density fluctuations are inferred to be strong on very small scales ($\\sim 10^8-10^{10} {cm}$). We argue that such density structures could correspond to the ionized boundaries of molecular regions (clouds) and demonstrate that the power-law distribution of scattering angles that is required to match the observations arises naturally from the expected intersections of our line of sight with randomly distributed, thin, approximately spherical ionized shells of this type. We show that the observed change in the time-broadening behavior for pulsar dispersion measures $\\lesssim 30 {\\rm pc} {\\rm cm}^{-3}$ is consistent with the expected effect of the general ISM turbulence, which should dominate the scattering for nearby pulsars. We also point out that if the clouds are ionized by nearby stars, then their boundaries may become turbulent on account of an ionization front instability. This turbulence could be an alternative cause of the inferred density structures. An additional effect that might contribute to the strength of the small-scale fluctuations in this case is the expected flattening of the turbulent density spectrum when the eddy sizes approach the proton gyroscale.

  4. An Overview of Observations by the Cassini Radio and Plasma Wave Investigation at Earth

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Hospodarsky, G. B.; Gurnett, D. A.; Kaiser, M. L.; Wahlund, J.-E.; Roux, A.; Canu, P.; Zarka, P.; Tokarev, Y.

    2001-01-01

    On August 18, 1999, the Cassini spacecraft flew by Earth at an altitude of 1186 km on its way to Saturn. Although the flyby was performed exclusively to provide the spacecraft with sufficient velocity to get to Saturn, the radio and plasma wave science (RPWS) instrument, along with several others, was operated to gain valuable calibration data and to validate the operation of a number of capabilities. In addition, an opportunity to study the terrestrial radio and plasma wave environment with a highly capable instrument on a swift fly-through of the magnetosphere was afforded by the encounter. This paper provides an overview of the RPWS observations, at Earth, including the identification of a number of magnetospheric plasma wave modes, an accurate measurement of the plasma density over a significant portion of the trajectory using the natural wave spectrum in addition to a relaxation sounder and Langmuir probe, the detection of natural and human-produced radio emissions, and the validation of the capability to measure the wave normal angle and Poynting flux of whistler-mode chorus emissions. The results include the observation of a double-banded structure at closest' approach including a band of Cerenkov emission bounded by electron plasma and upper hybrid frequencies and an electron cyclotron harmonic band just above the second harmonic of the electron cyclotron frequency. In the near-Earth plasma sheet, evidence for electron phase space holes is observed, similar to those first reported by Geotail in the magnetotail. The wave normal analysis confirms the Polar result that chorus is generated very close to the magnetic equator and propagates to higher latitudes. The integrated power flux of auroral kilometric radiation is also used to identify a series of substorms observed during the outbound passage through the magnetotail.

  5. Global mapping of ionospheric HF/VHF radio wave absorption due to solar energetic protons

    NASA Astrophysics Data System (ADS)

    Sauer, Herbert H.; Wilkinson, Daniel C.

    2008-12-01

    Simple, one-parameter algorithms are applied to the observed energetic proton flux as provided by instruments aboard the GOES series of satellites to yield estimates of the high-latitude HF and VHF radio wave absorption for day and night, respectively. These results are extended to full daily coverage by treating the effects of solar illumination, geomagnetic cutoff variation, and frequency dependence over the entire earth. Validation calculations of the polar cap absorption of HF radio waves have been performed for 11 larger solar energetic particle events during the period from 1992 to 2002 and the results are compared to observations of 30 MHz riometers operated by the Air Force Geophysics Laboratory and located at Thule, Greenland. Prediction of the minimum event duration from current flux level is also obtained, and a specimen presentation of the north and south polar caps illustrates the graphical output of the model for the peak of the 6 December 2006 solar proton event.

  6. Evidence for four- and three-wave interactions in solar type III radio emissions

    NASA Astrophysics Data System (ADS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2013-08-01

    The high time resolution observations obtained by the STEREO/WAVES experiment show that in the source regions of solar type III radio bursts, Langmuir waves often occur as intense localized wave packets with short durations of only few ms. One of these wave packets shows that it is a three-dimensional field structure with WLneTe ~ 10-3, where WL is the peak energy density, and ne and Te are the electron density and temperature, respectively. For this wave packet, the conditions of the oscillating two-stream instability (OTSI) and supersonic collapse are satisfied within the error range of determination of main parameters. The density cavity, observed during this wave packet indicates that its depth, width and temporal coincidence are consistent with those of a caviton, generated by the ponderomotive force of the collapsing wave packet. The spectrum of each of the parallel and perpendicular components of the wave packet contains a primary peak at fpe, two secondary peaks at fpe ± fS and a low-frequency enhancement below fS, which, as indicated by the frequency and wave number resonance conditions, and the fast Fourier transform (FFT)-based tricoherence spectral peak at (fpe, fpe, fpe + fS, fpe - fS), are coupled to each other by the OTSI type of four-wave interaction (fpe is the local electron plasma frequency and fS is the frequency of ion sound waves). In addition to the primary peak at fpe, each of these spectra also contains a peak at 2fpe, which as indicated by the frequency and wave number resonance conditions, and the wavelet-based bicoherence spectral peak at (fpe, fpe), appears to correspond to the second harmonic electromagnetic waves generated as a result of coalescence of oppositely propagating sidebands excited by the OTSI. Thus, these observations for the first time provide combined evidence that (1) the OTSI and related strong turbulence processes play a significant role in the stabilization of the electron beam, (2) the coalescence of the oppositely propagating up- and down-shifted daughter Langmuir waves excited by the OTSI probably is the emission mechanism of the second harmonic radiation, and (3) the Langmuir collapse follows the route of OTSI in some of the type III radio bursts.

  7. A Minimal Radio and Plasma Wave Investigation For a Mercury Orbiter Mission

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    2001-01-01

    The primary thrust of the effort at The University of Iowa for the definition of an orbiter mission to Mercury is a minimum viable radio and plasma wave investigation. While it is simple to add sensors and capability to any payload, the challenge is to do reasonable science within limited resources; and viable missions to Mercury are especially limited in payload mass. For a wave investigation, this is a serious concern, as the sensor mass often makes up a significant fraction of the instrumentation mass.

  8. Thunderstorms, lightning, sprites and magnetospheric whistler-mode radio waves

    E-print Network

    Siingh, Devendraa; Patel, R P; Singh, Rajesh; Singh, R P; Veenadhari, B; Mukherjee, M

    2009-01-01

    Thunderstorms and the lightning that they produce are inherently interesting phenomena that have intrigued scientists and mankind in general for many years. The study of thunderstorms has rapidly advanced during the past century and many efforts have been made towards understanding lightning, thunderstorms and their consequences. Recent observations of optical phenomena above an active lightning discharge along with the availability of modern technology both for data collection and data analysis have renewed interest in the field of thunderstorms and their consequences in the biosphere. In this paper, we review the electrification processes of a thunderstorm, lightning processes and their association with global electric circuit and climate. The upward lightning discharge can cause sprites, elves, jets, etc. which are together called transient luminous events. Their morphological features and effects in the mesosphere are reviewed. The wide spectrum of electromagnetic waves generated during lightning discharg...

  9. Phase Coupling in Langmuir Wave Packets: Evidence for Four Wave Interactions in Solar Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2012-01-01

    The four wave interaction process, known as the oscillating two stream instability (OTSI) is considered as one of the mechanisms responsible for stabilizing the electron beams associated with solar type III radio bursts. It has been reported that (1) an intense localized Langmuir wave packet associated with a type III burst contains the spectral characteristics of the OTSI: (a) a resonant peak at the local electron plasma frequency, f(sub pe), (b) a Stokes peak at a frequency slightly lower than f(sub pe), (c) anti-Stokes peak at a frequency slightly higher than f(sub pe), and (d) a low frequency enhancement below a few hundred Hz, (2) the frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI, and (3) the peak intensity of the wave packet is well above the thresholds for the OTSI as well as spatial collapse of envelope solitons. Here, for the first time, applying the trispectral analysis on this wave packet, we show that the tricoherence, which measures the degree of coherent four-wave coupling amongst the observed spectral components exhibits a peak. This provides an additional evidence for the OTSI and related spatial collapse of Langmuir envelope solitons in type III burst sources.

  10. Bispectral Analysis of a Langmuir Wave Packet Associated with a Solar Type III Radio Burst

    NASA Astrophysics Data System (ADS)

    Golla, T.; MacDowall, R. J.; Bergamo, M.

    2012-12-01

    We present the observations of an intense localized wave packet, obtained by the STEREO spacecraft in the source region of a solar type III radio burst. The FFT spectrum of this wave packet contains a primary peak at the local electron plasma frequency, fpe (Langmuir waves), and two secondary peaks, one at 2fpe (second harmonic) and a second one at 3fpe (third harmonic). The wavelet based time-frequency spectrogram indicates that these spectral peaks are coincident in time. It is found that the bicoherence spectrum, computed using the wavelet based bispectral analysis technique contains two peaks, one at (fpe, fpe) and a second one at (2fpe, fpe). The high values of the bicoherences of these spectral peaks, which quantify the phase coherences amongst the harmonic components provide unambiguous evidence for the three wave interactions L + L' -> T2f{pe}, and L + T2f{pe} -> T3f{pe} in the waveform data, where L and L' are the oppositely propagating Langmuir waves, and T2f{pe} and T3f{pe} are the second and third harmonic electromagnetic waves, respectively. The peak intensity and short duration of this wave packet, which indicate that it is probably a collapsing soliton formed as a result of oscillating two stream instability (OTSI), strongly suggest that the L and L' probably correspond to the OTSI excited oppositely propagating Langmuir waves.

  11. The Abundance of X-shaped Radio Sources: Implications for the Gravitational Wave Background

    NASA Astrophysics Data System (ADS)

    Roberts, David H.; Saripalli, Lakshmi; Subrahmanyan, Ravi

    2015-09-01

    Coalescence of supermassive black holes (SMBHs) in galaxy mergers is potentially the dominant contributor to the low frequency gravitational wave background (GWB). It was proposed by Merritt & Ekers that X-shaped radio galaxies are signposts of such coalescences and that their abundance might be used to predict the magnitude of the GWB. In Roberts et al. we presented radio images of all 52 X-shaped radio source candidates out of the sample of 100 selected by Cheung for which archival VLA data were available. These images indicate that at most 21% of the candidates might be genuine X-shaped radio sources that were formed by a restarting of beams in a new direction following a major merger. This suggests that fewer than 1.3% of extended radio sources appear to be candidates for genuine axis reorientations (“spin flips”), much smaller than the 7% suggested by Leahy & Parma. Thus, the associated GWB may be substantially smaller than previous estimates. These results can be used to normalize detailed calculations of the SMBH coalescence rate and the GWB.

  12. Radio Remnants of Compact Binary Mergers - the Electromagnetic Signal that will follow the Gravitational Waves

    E-print Network

    Ehud Nakar; Tsvi Piran

    2011-02-04

    The question "what is the observable electromagnetic (EM) signature of a compact binary merger?" is an intriguing one with crucial consequences to the quest for gravitational waves (GW). Compact binary mergers are prime sources of GW, targeted by current and next generation detectors. Numerical simulations have demonstrated that these mergers eject energetic sub-relativistic (or even relativistic) outflows. This is certainly the case if the mergers produce short GRBs, but even if not, significant outflows are expected. The interaction of such outflows with the surround matter inevitably leads to a long lasting radio signal. We calculate the expected signal from these outflows (our calculations are also applicable to short GRB orphan afterglows) and we discuss their detectability. We show that the optimal search for such signal should, conveniently, take place around 1.4 GHz. Realistic estimates of the outflow parameters yield signals of a few hundred $\\mu$Jy, lasting a few weeks, from sources at the detection horizon of advanced GW detectors. Followup radio observations, triggered by GW detection, could reveal the radio remnant even under unfavorable conditions. Upcoming all sky surveys can detect a few dozen, and possibly even thousands, merger remnants at any give time, thereby providing robust merger rate estimates even before the advanced GW detectors become operational. In fact, the radio transient RT 19870422 fits well the overall properties predicted by our model and we suggest that its most probable origin is a compact binary merger radio remnant.

  13. Effect exerted by a radio wave electromagnetic field on the rheological properties of water and portland-cement systems

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Belous, N. Kh.; Rodtsevich, S. P.; Koshevar, V. D.; Shkadretsova, V. G.; Goncharik, S. V.; Chubrik, N. I.; Orlovich, A. I.

    2013-09-01

    We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

  14. 4 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--I: REGULAR PAPERS, VOL. 56, NO. 1, JANUARY 2009 Design of Millimeter-Wave CMOS Radios: A Tutorial

    E-print Network

    Razavi, Behzad

    of Millimeter-Wave CMOS Radios: A Tutorial Behzad Razavi, Fellow, IEEE (Invited Paper) Abstract--This paper deals with the challenges in the design of millimeter-wave CMOS radios and describes circuit, a number of radio architectures that relax the generation, division, and distribution of the local

  15. Scintillator material

    DOEpatents

    Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

    1994-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  16. Scintillator material

    DOEpatents

    Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

    1992-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  17. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1994-06-07

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  18. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1992-07-28

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  19. Irregularities in ionospheric plasma clouds: Their evolution and effect on radio communication

    NASA Astrophysics Data System (ADS)

    Vesecky, J. F.; Chamberlain, J. W.; Cornwall, J. M.; Hammer, D. A.; Perkins, F. W.

    1980-09-01

    Both satellite radio communications, which travel through the Earth's ionosphere, and high frequency (HF) sky wave circuits, which use the ionosphere as a refracting medium, can be strongly affected by radio wave scintillation. High altitude nuclear explosions cause scintillation (by strongly disturbing the ionosphere) and thus severely degrade satellite radio communications over a large region. Since further atmospheric nuclear tests are banned, a thorough understanding of the physics involved in both the disturbed ionosphere and its interaction with radio waves is necessary in order to design radio communications systems which will operate satisfactorily in a nuclear environment. During the 1980 JASON Summer Study we addressed some aspects of the evolution of ionospheric irregularities following a high altitude nuclear explosion--the radio wave propagation theory being apparently well understood for the satellite link case. In particular, we have worked on irregularity evolution at late times (approx. hours) after an explosion and the impact of early time irregularity structure on late time evolution. We also raise the question of scintillation effects on HF sky wave communications.

  20. Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts

    NASA Astrophysics Data System (ADS)

    Graham, D. B.; Cairns, Iver H.

    2014-04-01

    The nonlinear processes and evolution of Langmuir waves in the source regions of type III solar radio bursts are explored in detail. Langmuir waves recorded by the Time Domain Sampler of the STEREO/WAVES instrument can be roughly classified into six groups based on the waveform, power spectra, and field strength perpendicular to the local magnetic field. It is argued that these groups correspond to either different stages of the evolution of Langmuir waves generated by electron beams or differ due to the direction of the magnetic field relative to the solar wind velocity. Approximately half of the observed Langmuir waves have strong perpendicular fields, meaning that understanding how these fields are produced is crucial for understanding type III sources. Most events recorded are either localized waveforms consistent with Langmuir eigenmodes or have two or more spectral peaks consistent with electrostatic (ES) decay of Langmuir/z mode waves. The remaining events appear to correspond to either earlier or later stages of Langmuir wave evolution or are decay events for which the Doppler shift is insufficient to distinguish the beam-driven and product Langmuir waves. This is supported by the fact that most events exceed the threshold for ES decay even though their spectra show no evidence for decay and some of the events are observed when the solar wind flow is approximately perpendicular to the magnetic field, minimizing Doppler shifting. Low-frequency fields produced by intense Langmuir waves are quantitatively consistent with density perturbations produced by the ponderomotive force, ion-acoustic waves produced by ES decay, or sheath rectification. Above the observed nonlinear threshold, quantitative analysis suggests that the observed low-frequency signals are consistent with perturbations produced by ponderomotive effects and ion-acoustic waves produced by ES decay, but effects of sheath rectification may also contribute.

  1. Radial distribution of compressive waves in the solar corona revealed by Akatsuki radio occultation observations

    SciTech Connect

    Miyamoto, Mayu; Imamura, Takeshi; Ando, Hiroki; Toda, Tomoaki; Nakamura, Masato; Tokumaru, Munetoshi; Shiota, Daikou; Isobe, Hiroaki; Asai, Ayumi; Häusler, Bernd; Pätzold, Martin; Nabatov, Alexander

    2014-12-10

    Radial variations of the amplitude and the energy flux of compressive waves in the solar corona were explored for the first time using a spacecraft radio occultation technique. By applying wavelet analysis to the frequency time series taken at heliocentric distances of 1.5-20.5 R{sub S} (solar radii), quasi-periodic density disturbances were detected at almost all distances. The period ranges from 100 to 2000 s. The amplitude of the fractional density fluctuation increases with distance and reaches ?30% around 5 R{sub S} , implying that nonlinearity of the wave field is potentially important. We further estimate the wave energy flux on the assumption that the observed periodical fluctuations are manifestations of acoustic waves. The energy flux increases with distance below ?6 R{sub S} and seems to saturate above this height, suggesting that the acoustic waves do not propagate from the low corona but are generated in the extended corona, probably through nonlinear dissipation of Alfvén waves. The compressive waves should eventually dissipate through shock generation to heat the corona.

  2. Discovery of millimetre-wave excess emission in radio-quiet active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Behar, Ehud; Baldi, Ranieri D.; Laor, Ari; Horesh, Assaf; Stevens, Jamie; Tzioumis, Tasso

    2015-07-01

    The physical origin of radio emission in radio-quiet active galactic nuclei (RQ AGN) remains unclear, whether it is a downscaled version of the relativistic jets typical of radio-loud (RL) AGN, or whether it originates from the accretion disc. The correlation between 5 GHz and X-ray luminosities of RQ AGN, which follows LR = 10-5LX observed also in stellar coronae, suggests an association of both X-ray and radio sources with the accretion disc corona. Observing RQ AGN at higher (mm-wave) frequencies, where synchrotron self-absorption is diminished, and smaller regions can be probed, is key to exploring this association. Eight RQ AGN, selected based on their high X-ray brightness and variability, were observed at 95 GHz with the CARMA (Combined Array for Research in Millimetre-wave Astronomy) and ATCA (the Australia Telescope Compact Array) telescopes. All targets were detected at the 1-10 mJy level. Emission excess at 95 GHz of up to ×7 is found with respect to archival low-frequency steep spectra, suggesting a compact, optically thick core superimposed on the more extended structures that dominate at low frequencies. Though unresolved, the 95 GHz fluxes imply optically thick source sizes of 10-4-10-3 pc, or ˜10-1000 gravitational radii. The present sources lie tightly along an LR (95 GHz) = 10-4LX (2-10 keV) correlation, analogous to that of stellar coronae and RQ AGN at 5 GHz, while RL AGN are shown to have higher LR/LX ratios. The present observations argue that simultaneous mm-wave and X-ray monitoring of RQ AGN features a promising method for understanding accretion disc coronal emission.

  3. Computational strategy for modeling radio wave propagation in lossy circular waveguides

    SciTech Connect

    Moses, Ronald; Cai, D Michael

    2008-01-01

    The propagation of radio waves in lossy waveguides and tunnels has been researched extensively for many years as can be seen in the detailed book by Wait. The mathematics used to model waveguides for communications is essentially the same as that needed to model radio frequency (RF) propagation in simple tunnels. The presence or lack of conductors inside a waveguide or tunnel is a key driver in the nature of the solutions one will find for a particular application, Delogne. When there are conductors passing through a waveguide or tunnel, the simplest modes of propagation are surface-guided waves following the conductor and typically enabling long-range transmission. A tunnel containing a core conductor can act rather like a coaxial cable, propagating waves at a nearly constant speed, regardless of frequency. Conversely, a tunnel or waveguide without internal conductors is subject to very different wave patterns, resulting in a much more complex propagation analysis. Holloway et al. presented an exhaustive study of RF propagation in circular structures embedded in lossy surroundings. The work of Holloway et al. is the basis for this paper, where we discuss application of their computational techniques and present refinements gleaned from our work on similar problems.

  4. Analysis and simulation of standing wave pattern of powerful HF radio waves in ionospheric reflection region

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Zhou, Chen; Zhao, Zheng-Yu; Yang, Xu-Bo

    2015-12-01

    For the study of the various non-linear effects generated in ionospheric modulation experiments, accurate calculation of the field intensity variation in the whole reflection region for an electromagnetic wave vertically impinging upon the ionosphere is meaningful. In this paper, mathematical expressions of the electric field components of the characteristic heating waves are derived, by coupling the equation describing a wave initially impinging vertically upon the ionosphere with the Forsterling equation. The variation of each component of the electric field and the total electric field intensity of the standing wave pattern under a specific density profile are calculated by means of a uniform approximation, which is applied throughout the region near the reflection point. The numerical calculation results demonstrate that the total electric field intensity of the ordinary (O)-mode wave varies rapidly in space and reaches several maxima below the reflection point. Evident swelling phenomena of the electric field intensity are found. Our results also indicate that this effect is more pronounced at higher latitudes and that the geomagnetic field is important for wave pattern variation. The electric field intensity of the standing wave pattern of the extraordinary (X)-mode wave exhibits some growth below the reflection point, but its swelling effect is significantly weaker than that of the O-mode wave.

  5. An Experiment Study of the Propagation of Radio Waves in a Scaled Model of Long-Wall Coal Mining Tunnels

    SciTech Connect

    Han, G.R.; Zhang, W.M.; Zhang, Y.P.

    2009-07-01

    A long-wall coal mining tunnel is the most important working area in a coal mine. It has long been realized that radio communications can improve both productivity and safety in this dangerous area. Hence, many attempts to use radio communications in such an environment have been made. Unfortunately, no radio system has satisfactorily provided communication services there, which, we believe, is partially due to poor understanding of the propagation characteristics of radio waves in the long-wall mining tunnel. To have deeper physical insight into the propagation problem, a scaled model of the long-wall mining tunnel was built, and the propagation characteristics of UHF radio waves were measured. The experiment and the measured results are presented and discussed.

  6. Ion Acoustic Wave Frequencies and Onset Times During Type 3 Solar Radio Bursts

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Robinson, P. A.

    1995-01-01

    Conflicting interpretations exist for the low-frequency ion acoustic (S) waves often observed by ISEE 3 in association with intense Langmuir (L) waves in the source regions of type III solar radio bursts near 1 AU. Two indirect lines of observational evidence, as well as plasma theory, suggest they are produced by the electrostatic (ES) decay L yields L(PRIME) + S. However, contrary to theoretical predictions, an existing analysis of the wave frequencies instead favors the electromagnetic (EM) decays L yields T + S, where T denotes an EM wave near the plasma frequency. This conflict is addressed here by comparing the observed wave frequencies and onset times with theoretical predictions for the ES and EM decays, calculated using the time-variable electron beam and magnetic field orientation data, rather than the nominal values used previously. Field orientation effects and beam speed variations are shown analytically to produce factor-of-three effects, greater than the difference in wave frequencies predicted for the ES and EM decays; effects of similar magnitude occur in the events analyzed here. The S-wave signals are extracted by hand from a sawtooth noise background, greatly improving the association between S waves and intense L waves. Very good agreement exists between the time-varying predictions for the ES decay and the frequencies of most (but not all) wave bursts. The waves occur only after the ES decay becomes kinematically allowed, which is consistent with the ES decay proceeding and producing most of the observed signals. Good agreement exists between the EM decay's predictions and a significant fraction of the S-wave observations while the EM decay is kinematically allowed. The wave data are not consistent, however, with the EM decay being the dominant nonlinear process. Often the observed waves are sufficiently broadband to overlap simultaneously the frequency ranges predicted for the ES and EM decays. Coupling the dominance of the ES decay with this frequency overlap provides support for a previous suggestion that fundamental emission occurs when the EM decay is stimulated by the ES decay product waves. The periods in which the ES and EM decays produce observable S waves are consistent with the observed and (independently) predicted times of fundamental and harmonic radio emission. This supports interpretation of fundamental emission as stimulated EM decay and harmonic emission as the coalescence L + L(prime) yields T of beam-generated L waves and L(prime) waves produced by the ES decay, where T denotes an electromagnetic wave at twice the plasma frequency. Analysis of the electron beam data reveals that the time-varying beam speed is consistent with ballistic beam propagation with minimal energy loss, implying that the beam propagates in a state close to time- and volume-averaged marginal stability. This confirms a central tenet of the stochastic growth theory for type III bursts.

  7. Verification of particle simulation of radio frequency waves in fusion plasmas

    SciTech Connect

    Kuley, Animesh; Lin, Z.; Fusion Simulation Center, Peking University, Beijing 100871 ; Wang, Z. X.; Wessel, F.

    2013-10-15

    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.

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

    DOEpatents

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

    1999-01-01

    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.

  9. Prospects for joint radio telescope and gravitational wave searches for astrophysical transients

    E-print Network

    V. Predoi; J. Clark; T. Creighton; E. Daw; S. Fairhurst; I. S. Heng; J. Kanner; T. Regimbau; P. Shawhan; X. Siemens; P. Sutton; A. Vecchio; D. White; G. Woan

    2009-12-02

    The radio skies remain mostly unobserved when it comes to transient phenomena. The direct detection of gravitational waves will mark a major milestone of modern astronomy, as an entirely new window will open on the universe. Two apparently independent phenomena can be brought together in a coincident effort that has the potential to boost both searches. In this paper we will outline the scientific case that stands behind these future joint observations and will describe the methods that might be used to conduct the searches and analyze the data. The targeted sources are binary systems of compact objects, known to be strong candidate sources for gravitational waves. Detection of transients coincident in these two channels would be a significant smoking gun for first direct detection of gravitational waves, and would open up a new field for characterization of astrophysical transients involving massive compact objects.

  10. Creation of visible artificial optical emissions in the aurora by high-power radio waves.

    PubMed

    Pedersen, Todd R; Gerken, Elizabeth A

    2005-02-01

    Generation of artificial light in the sky by means of high-power radio waves interacting with the ionospheric plasma has been envisaged since the early days of radio exploration of the upper atmosphere, with proposed applications ranging from regional night-time street lighting to atmospheric measurements. Weak optical emissions have been produced for decades in such ionospheric 'heating' experiments, where they serve as key indicators of electron acceleration, thermal heating, and other effects of incompletely understood wave-particle interactions in the plasma under conditions difficult to replicate in the laboratory. The extremely low intensities produced previously have, however, required sensitive instrumentation for detection, preventing applications beyond scientific research. Here we report observations of radio-induced optical emissions bright enough to be seen by the naked eye, and produced not in the quiet mid-latitude ionosphere, but in the midst of a pulsating natural aurora. This may open the door to visual applications of ionospheric heating technology or provide a way to probe the dynamics of the natural aurora and magnetosphere. PMID:15690034

  11. Creation of visible artificial optical emissions in the aurora by high-power radio waves

    NASA Astrophysics Data System (ADS)

    Pedersen, Todd. R.; Gerken, Elizabeth A.

    2005-02-01

    Generation of artificial light in the sky by means of high-power radio waves interacting with the ionospheric plasma has been envisaged since the early days of radio exploration of the upper atmosphere, with proposed applications ranging from regional night-time street lighting to atmospheric measurements. Weak optical emissions have been produced for decades in such ionospheric `heating' experiments, where they serve as key indicators of electron acceleration, thermal heating, and other effects of incompletely understood wave-particle interactions in the plasma under conditions difficult to replicate in the laboratory. The extremely low intensities produced previously have, however, required sensitive instrumentation for detection, preventing applications beyond scientific research. Here we report observations of radio-induced optical emissions bright enough to be seen by the naked eye, and produced not in the quiet mid-latitude ionosphere, but in the midst of a pulsating natural aurora. This may open the door to visual applications of ionospheric heating technology or provide a way to probe the dynamics of the natural aurora and magnetosphere.

  12. Beat-type Langmuir wave emissions associated with a type III solar radio burst: Evidence of parametric decay

    NASA Technical Reports Server (NTRS)

    Hospodarsky, G. B.; Gurnett, D. A.

    1995-01-01

    Recent measurements from the plasma wave instrument on the Galileo spacecraft have shown that Langmuir waves observed in conjunction with a type III solar radio burst contain many beat-type waveforms, with beat frequencies ranging from about 150 to 650 Hz. Strong evidence exists that the beat pattern is produced by two closely spaced narrowband components. The most likely candidates for these two waves are a beam-generated Langmuir wave and an oppositely propagating Langmuir wave produced by parametric decay. In the parametric decay process, nonlinear interactions cause the beam-driven Langmuir wave to decay into a Langmuir wave and a low-frequency ion sound wave. Comparisons of the observed beat frequency are in good agreement with theoretical predictions for a three-wave parametric decay process. Weak low-frequency emissions are also sometimes observed at the predicted frequency of the ion sound wave.

  13. Review of radio wave for power transmission in medical applications with safety

    NASA Astrophysics Data System (ADS)

    Day, John; Geddis, Demetris; Kim, Jaehwan; Choi, Sang H.; Yoon, Hargsoon; Song, Kyo D.

    2015-04-01

    The integration of biosensors with radio frequency (RF) wireless power transmission devices is becoming popular, but there are challenges for implantable devices in medical applications. Integration and at the same time miniaturization of medical devices in a single embodiment are not trivial. The research reported herein, seeks to review possible effects of RF signals ranging from 900 MHz to 100 GHz on the human tissues and environment. Preliminary evaluation shows that radio waves selected for test have substantial influence on human tissues based on their dielectric properties. In the advancement of RF based biosensors, it is imperative to set up necessary guidelines that specify how to use RF power safely. In this paper, the dielectric properties of various human tissues will be used for estimation of influence within the selected RF frequency ranges.

  14. High-frequency radio-wave ablation of osteoid osteoma in the lumbar spine.

    PubMed

    Osti, O L; Sebben, R

    1998-01-01

    The authors report on the first known application in the spine of percutaneous ablation of osteoid osteoma using radio-frequency waves. The technique involves a CT-guided biopsy of the lesion followed by introduction of a 1-mm probe connected to a radio-frequency lesion generator. The procedure was performed on an outpatient basis and the patient experienced immediate relief of his symptoms. No evidence of recurrence was demonstrated 16 months later. The technique++ described may become the procedure of choice in the surgical treatment of osteoid osteoma, as it minimises surgical trauma and post-operative pain. Longer follow-ups are required to monitor the incidence of recurrence. PMID:9840478

  15. Effects in the ionosphere and HF radio-wave propagation during an intense substorm

    NASA Astrophysics Data System (ADS)

    Blagoveshchensky, D. V.; Borisova, T. D.; Rogov, D. D.

    2010-08-01

    We present the results of combined radiophysical studies during the period of an intense magnetospheric substorm which occurred from 00:00 to 02:00 UT in April 12, 1999. Measurements of the ionospheric parameters by a chain of European ionosondes for this period were compared with the variations in ionospheric parameters averaged over more than 70 substorms. The latter variations were obtained by data from the ionosondes of Europe, Central Siberia, and North America in 1993-1999. Data from the CUTLASS radar as well as the DMSP and POES satellites were used for the analysis of the April 11-12 substorm. Numerical calculations of HF radio-wave propagation on the St. Petersburg—Longyearbyen (Svalbard) high-latitude path were carried out by the ray tracing technique. Two simultaneous effects have been revealed in the ionosphere. One occurs immediately during the substorm and another is associated with the end of the magnetic storm in April 10, 1999. According to the CUTLASS radar data, the number of backscattering irregularities in the ionospheric F layer notably decreased during the substorm expansion phase. Satellite data showed an increase in the “soft” (hundreds of eV) particle precipitation before and after the substorm. Numerical calculations of HF radio-wave propagation on the St. Petersburg—Longyearbyen path have demonstrated an essential change of propagation mechanisms during the substorm and a tangible change in the wave arrival angles before and after the substorm.

  16. Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts

    NASA Astrophysics Data System (ADS)

    Vidojevic, S.; Zaslavsky, A.; Maksimovic, M.; Drazic, M.; Hoang, S.; Atanckovic, O.

    2010-12-01

    Interplanetary electron beams, produced by CMEs and flares, are unstable in the solar wind and generate Langmuir waves at the local plasma frequency (fp) or its harmonic (2fp). Radio observations of the waves in a range of 4 - 256 kHz from the WAVES experiment on-board the WIND spacecraft have been statistically analyzed. From the radio observations starting from November 1994 to the beginning of 2010 a subset of about 180 events, with Langmuir waves and type III bursts occurred at the same time, has been selected. In order to exclude events that do not originate directly from the Sun and events that do not coincide with energetic electrons events, we have used measurements of interplanetary magnetic field vector, three-dimensional distribution of supra-thermal electrons and ions and three-dimensional velocity, density and temperature of the solar wind ions -- all taken simultaneously by the four experiments on-board the WIND spacecraft. The measurements allow qualitative analysis of the events which led to the final subset of 36 events that has been selected for this study. In order to remove the background consisting of thermal noise, type III bursts and Galactic background, we have developed a heuristic algorithm based on numerical techniques with a few parameters only. After background has been removed, the remaining power spectral density has been modeled by Pearson system of probability distributions. The coefficients of the probability distributions have been calculated by using two methods: method of moments and maximum likelihood estimation method. We have shown that the probability distributions of the power spectral density of the Langmuir waves belong to the three main types of Pearson probability distributions: type I, type IV and type VI. In order to compare the goodness of the fits, a few statistical tests have been applied, showing for all of the considered events that the Pearson probability distributions fit the data better than the Gaussian ones.

  17. Radio Wave Propagation for Communication on and around Mars. Part 1; Highlights: Propagation Through Mars Environment

    NASA Technical Reports Server (NTRS)

    Ho, Christian; Golshan, Nasser

    1999-01-01

    We recommend to use the dayside Martian ionosphere as a reflector for global communication, because the dayside ionosphere has stable density peak and usable critic frequency. This is very crucial for the future Mars ground to around communication. The dayside ionosphere has been well modeled as a Chapman layer. We suggest to perform the Martian nightside ionospheric modeling study. Because the nightside ionosphere has very little measurements available, we propose to drop a digital ionosond instrument into the Mars surface for data collection. Even though the Martian tropospheric radio refractivity has small value, it still can cause the ray bending and multipath effects. We recommend to perform an accurate calculation on excess phase and group delays (range and time delays). Other effects, such as range rate errors, appearance angle deviation, defocusing loss on Mars, etc. are also needed to be estimated. Ice depolarization effects due to Martian clouds on radio waves is unknown yet, which is expected to be small, because lower optical depth and thinner layer of cloud: Total Martian atmospheric gaseous attenuation is expected to be less than 1 dB on microwaves band, because the Martian atmosphere has very low concentration in uncondensed H2O and O2. An accurate calculation for zenith opacity requires the information about scale heights of H2O and O2 distribution. An accurate water vapor altitude profile at Mars is not available yet. Under the normal condition, CO2 and N2 gases do not have electric or magnetic dipoles and do not absorb electromagnetic energy from the waves. However, they may generate the dipoles through a collision and interact with waves under a high density condition and absorb electromagnetic waves in the infrared and visible band. Dust storm is most dominant factor to the radio wave attenuation. Large Martian dust storm can cause at least 3 dB or higher loss to Ka band wave. For a normal dust storm, the attenuation is about 1 dB. The attenuation much depends on dust mass loading, dust size distribution, etc. Most large dust storm occur in the southern hemisphere during later spring and early summer when the southern hemisphere become suddenly hot.

  18. Ultracold atoms in radio-frequency-dressed potentials beyond the rotating wave approximation

    E-print Network

    S. Hofferberth; B. Fischer; T. Schumm; J. Schmiedmayer; I. Lesanovsky

    2007-08-01

    We study dressed Bose-Einstein condensates in an atom chip radio-frequency trap. We show that in this system sufficiently strong dressing can be achieved to cause the widely used rotating wave approximation (RWA) to break down. We present a full calculation of the atom - field coupling which shows that the non-RWA contributions quantitatively alter the shape of the emerging dressed adiabatic potentials. The non-RWA contributions furthermore lead to additional allowed transitions between dressed levels. We use RF spectroscopy of Bose-Einstein condensates trapped in the dressed state potentials to directly observe the transition from the RWA to the beyond-RWA regime.

  19. Gravity waves above Andes detected from GPS radio occultation temperature profiles: Mountain forcing?

    NASA Astrophysics Data System (ADS)

    de la Torre, A.; Alexander, P.

    2005-09-01

    A significant wave activity in the upper troposphere and lower stratosphere at midlatitudes (30-40S) above the Andes Range was recently detected from Global Positioning System Radio Occultation (GPS RO) temperature profiles, retrieved from SAC-C (Satélite de Aplicaciones Cientficas-C) and CHAMP (CHAllenging Minisatellite Payload) satellites. Previously, large amplitude, long vertical wavelength structures have been reported in this region, as detected from other limb-sounding devices and have been identified as mountain waves (MWs). The capability of GPS RO observations to detect typical MWs with horizontal wavelengths shorter than 150 km, as well as the proper association of the observed wave activity to mountain forcing is put in doubt. Other three possible sources are discussed. In particular, the generation of inertio-gravity waves by geostrophic adjustment near to a permanent jet situated above the mountains, may constitute another important mechanism in this region. These waves may possess longer horizontal and perhaps shorter vertical wavelengths than those typically expected in MWs and could be more easily detected from limb-sounding profiles. The ``jet'' mechanism will be discussed in a second paper.

  20. High Power Radio Wave Interactions within the D-Region Ionosphere

    NASA Astrophysics Data System (ADS)

    Moore, R. C.

    2014-12-01

    This paper highlights the best results obtained during D-region modification experiments performed by the University of Florida at the High-frequency Active Auroral Research Program (HAARP) observatory between 2007 and 2014. Over this period, we have seen a tremendous improvement in ELF/VLF wave generation efficiency. We have identified methods to characterize ambient and modified ionospheric properties and to discern and quantify specific types of interactions. We have demonstrated several important implications of HF cross-modulation effects, including "Doppler Spoofing" on HF radio waves. Throughout this talk, observations are compared with the predictions of an ionospheric HF heating model to provide context and guidance for future D-region modification experiments.

  1. Satellite radio occultation investigations of internal gravity waves in the planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander

    Internal gravity waves (IGWs) modulate the structure and circulation of the Earth’s atmosphere, producing quasi-periodic variations in the wind velocity, temperature and density. Similar effects are anticipated for the Venus and Mars since IGWs are a characteristic of stably stratified atmosphere. In this context, an original method for the determination of IGW parameters from a vertical temperature profile measurement in a planetary atmosphere has been developed [Gubenko et al., 2008, 2011, 2012]. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, the analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitudes of the wave field and on the linear IGW saturation theory in which these amplitudes are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal wave reaches the shear instability threshold, energy is assumed to be dissipated in such a way that the IGW amplitude is maintained at the instability threshold level as the wave propagates upwards. We have extended the developed technique [Gubenko et al., 2008] in order to reconstruct the complete set of wave characteristics including such important parameters as the wave kinetic and potential energy per unit mass and IGW fluxes of the energy and horizontal momentum [Gubenko et al., 2011]. We propose also an alternative method to estimate the relative amplitudes and to extract IGW parameters from an analysis of perturbations of the Brunt-Vaislala frequency squared [Gubenko et al., 2011]. An application of the developed method to the radio occultation (RO) temperature data has given the possibility to identify the IGWs in the Earth's, Martian and Venusian atmospheres and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal wind velocity perturbations, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy per unit mass, vertical fluxes of the wave energy and horizontal momentum. Vertical profiles of temperature retrieved from RO measurements of the CHAMP (Earth), Mars Global Surveyor (Mars), Magellan and Venus Express (Venus) missions are used and analyzed to identify discrete or “narrow spectral” wave events and to determine IGW characteristics in the Earth’s, Martian and Venusian atmospheres. This work was partially supported by the RFBR grant 13-02-00526-? and Program 22 of the RAS Presidium. References. Gubenko V.N., Pavelyev A.G., Andreev V.E. Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement // J. Geophys. Res. 2008. V. 113. No.D08109, doi:10.1029/2007JD008920. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Pavelyev A.A. Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth’s atmosphere // Atmos. Meas. Tech. 2011. V. 4. No.10. P. 2153-2162, doi:10.5194/amt-4-2153-2011. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Andreev V.E. A method for determination of internal gravity wave parameters from a vertical temperature or density profile measurement in the Earth’s atmosphere // Cosmic Res. 2012. V. 50. No.1. P. 21-31, doi: 10.1134/S0010952512010029.

  2. Simulator-probe for diagnostic testing of short-wave radio channels

    NASA Astrophysics Data System (ADS)

    Gasparyan, Y. M.; Movsesyan, R. M.; Oganesyan, M. G.; Poliyevskiy, G. A.; Shirinyan, P. A.

    1984-05-01

    Introduction of channel multiplexing equipment into short-wave radio channels requires prior diagnostic testing of these radio channels. A probe was developed predistorts the discrete signal in conformance with the characteristics of the channel multiplexing equipment. The simulator-probe generates equences of video pulses with + or - 20 V and + or - 9 V amplitudes respectively. This probe is capable of estimating the corrective capability of a tested radio channel with regenerator and channel inspection with a ring-type phase indicator. The probe includes a pulse generator and its output signals are transmitted to two channels. A wobbling device connected through a switch simulates swinging shift of the regenerated signal. Constant-bias and random-bias distortions are simulated by a rise-time and fall-time discriminator. A switch directs the output pulses of this discriminator to a random-bias module. Phase matching of the internal channel signal and the external predistorted signal is effected by means of a cycle phasing device. The ring-type indicator reads the phase after it is synchronized. The entire probe is built with a high degree of circuit integration using series K155 microchips. Experimental operation of its first prototype that it is a convenient and very reliable devices.

  3. A novel idea of purposefully affecting radio wave propagation by coherent acoustic source-induced atmospheric refractivity fluctuation

    NASA Astrophysics Data System (ADS)

    Gong, Shuhong; Yan, Daopu; Wang, Xuan

    2015-10-01

    The mechanism generating the array-distributed atmospheric refractivity fluctuation by a coherent acoustic source is analyzed. The theoretical model is established, which is used to quantifiably analyze the array structure of the artificial dielectric irregularities. It is qualitatively validated that the array-distributed artificial dielectric irregularities really exist and that the array structure of the artificial dielectric irregularities and the scattering effect of the artificial dielectric irregularities on a radio wave can be controlled by adjusting and selecting the optimized parameters of the transmitted acoustic wave and the adopted acoustic antenna array. It can be concluded that the array-distributed artificial dielectric irregularities can be used to purposefully affect radio wave propagation. After radio acoustic sounding system, the idea of this paper is a novel development in the field of the tropospheric atmospheric refractivity artificial abnormality technique and its applications.

  4. Ionospheric disturbances during November 30-December 1, 1988. XI - Abnormal propagations of HF and VHF radio waves

    NASA Astrophysics Data System (ADS)

    Ichinose, Masaru; Kamata, Mitsuhiro

    1992-07-01

    Unusual propagations of HF and VHF radio waves associated with a geomagnetic storm during the period from November 30 to December 1, 1988 are investigated using ionospheric data collected from Japan, China, and Taiwan. The increased field strength of the Japanese frequency standard signals (JJY 2.5 MHz and 5 MHz) which were received at Akita Radio Wave Observatory on the night of November 30 seem to have been caused by increased MUFs and/or scattering due to the disturbed ionosphere. The VHF-TV radio waves propagated from China were received at Kokubunji in Tokyo. One of the most probable mechanisms explaining this unusual propagation of VHF is a one-hop-F2 mode of propagation created by an ionosphere with an anomalously high f0F2. It was found out that these unusual HF and VHF propagations were attributed to unusual ionospheric conditions associated with these geomagnetic disturbances.

  5. Interplanetary dust detection by radio antennas: Mass calibration and fluxes measured by STEREO/WAVES

    NASA Astrophysics Data System (ADS)

    Zaslavsky, A.; Meyer-Vernet, N.; Mann, I.; Czechowski, A.; Issautier, K.; Le Chat, G.; Pantellini, F.; Goetz, K.; Maksimovic, M.; Bale, S. D.; Kasper, J. C.

    2012-05-01

    We analyze dust impacts recorded by the S/WAVES radio instrument onboard the two STEREO spacecraft near 1 A.U. during the period 2007-2010. The impact of a dust particle on a spacecraft produces a plasma cloud whose associated electric field can be detected by on-board electric antennas. For this study we use the electric potential time series recorded by the waveform sampler of the instrument. The high time resolution and long sampling times of this measurement enable us to deduce considerably more information than in previous studies based on the dynamic power spectra provided by the same instrument or by radio instruments onboard other spacecraft. The large detection area compared to conventional dust detectors provides flux data with a better statistics. We show that the dust-generated signals are of two kinds, corresponding to impacts of dust from distinctly different mass ranges. We propose calibration formulas for these signals and show that we are able to use S/WAVES as a dust detector with convincing results both in the nanometer and micrometer size ranges. In the latter, the orbital motion of the spacecraft enables us to distinguish between interstellar and interplanetary dust components. Our measurements cover the mass intervals ˜10-22-10-20 kg and ˜10-17 - 5 × 10-16 kg. The flux of the larger dust agrees with measurements of other instruments on different spacecraft.

  6. SDN based millimetre wave radio over fiber (RoF) network

    NASA Astrophysics Data System (ADS)

    Amate, Ahmed; Milosavljevic, Milos; Kourtessis, Pandelis; Robinson, Matthew; Senior, John M.

    2015-01-01

    This paper introduces software-defined, millimeter Wave (mm-Wave) networks with Radio over Fiber (RoF) for the delivery of gigabit connectivity required to develop fifth generation (5G) mobile. This network will enable an effective open access system allowing providers to manage and lease the infrastructure to service providers through unbundling new business models. Exploiting the inherited benefits of RoF, complete base station functionalities are centralized at the edges of the metro and aggregation network, leaving remote radio heads (RRHs) with only tunable filtering and amplification. A Software Defined Network (SDN) Central Controller (SCC) is responsible for managing the resource across several mm-Wave Radio Access Networks (RANs) providing a global view of the several network segments. This ensures flexible resource allocation for reduced overall latency and increased throughput. The SDN based mm-Wave RAN also allows for inter edge node communication. Therefore, certain packets can be routed between different RANs supported by the same edge node, reducing latency. System level simulations of the complete network have shown significant improvement of the overall throughput and SINR for wireless users by providing effective resource allocation and coordination among interfering cells. A new Coordinated Multipoint (CoMP) algorithm exploiting the benefits of the SCC global network view for reduced delay in control message exchange is presented, accounting for a minimum packet delay and limited Channel State Information (CSI) in a Long Term Evolution-Advanced (LTE-A), Cloud RAN (CRAN) configuration. The algorithm does not require detailed CSI feedback from UEs but it rather considers UE location (determined by the eNB) as the required parameter. UE throughput in the target sector is represented using a Cumulative Distributive Function (CDF). The drawn characteristics suggest that there is a significant 60% improvement in UE cell edge throughput following the application, in the coordinating cells, of the new CoMP algorithm. Results also show a further improvement of 36% in cell edge UE throughput when eNBs are centralized in a CRAN backhaul architecture. The SINR distribution of UEs in the cooperating cells has also been evaluated using a box plot. As expected, UEs with CoMP perform better demonstrating an increase of over 2 dB at the median between the transmission scenarios.

  7. Effect of electron-density gradients on propagation of radio waves in the mid-latitude trough. Master's thesis

    SciTech Connect

    Citrone, P.J.

    1991-01-01

    Partial contents of this thesis include: (1) Radio-wave propagation and the mid-latitude trough; (2) Ionospheric measurements; (3) Modification of time-dependent ionospheric model output with latitudinal electron-density profiles from digisonde trough depictions; (4) Ray-tracing simulations to examine ground range; and (5) Effects of three-dimensional gradients in electron density on radio-wave propagation in the trough region. Data is tabulated for geophysical conditions, solar activity level, geomagnetic activity level, conditions for vertical ray refraction to surface, and ray-tracing fixed-input conditions.

  8. Some key technologies for millimeter-wave radio-over-fiber systems based on injection locked lasers

    NASA Astrophysics Data System (ADS)

    Chen, Zhangyuan; Hu, Weiwei; Hong, Cheng; Zhang, Cheng; Li, Mingjin; Chen, Yushu; Wang, Xiang

    2008-11-01

    The seamless integration of broadband optical and wireless access networks is considered to be a promising solution for next generation access networks which will provide high capacity and flexibility with lower cost. In such access networks millimeter wave (mm-wave) radio over fiber (RoF) system is a key enabling technology due to its its large bandwidth and short reach in atmosphere. In this paper, we will discuss some key technologies based on injection locked lasers for mm-wave RoF systems, including all optical generation of mm-wave signal, up- and down-conversion, single sideband modulation, and transmission.

  9. Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys

    E-print Network

    Cregg C. Yancey; Brandon E. Bear; Bernadine Akukwe; Kevin Chen; Jayce Dowell; Jonathan D. Gough; Jonah Kanner; Michael Kavic; Kenneth Obenberger; Peter Shawhan; John H. Simonetti; Gregory B. Taylor; Jr-Wei Tsai

    2015-10-23

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of gravitational waves and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, LOFAR and MWA. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a $\\usim 30$ second time window and $\\usim 200 \\mendash 500 \\punits{deg}^{2}$ sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a \\emph{prompt} radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of $\\usim 2$. For some models, we also map the parameter space that may be constrained by non-detections.

  10. The radio waves & thermal electrostatic noise spectroscopy (SORBET) experiment on BepiColombo/MMO/PWI and the importance of radio HF measurements at Mercury

    NASA Astrophysics Data System (ADS)

    Moncuquet, M.; Matsumoto, H.; Bougeret, J.-L.; Issautier, K.; Kojima, H.; Maksimovic, M.; Meyer-Vernet, N.; Zarka, P.

    SORBET (Spectroscopie des Ondes Radio & du Bruit Electrostatique Thermique) is a radio HF spectrometer designed for the radio and Plasma Waves Instrument (PWI) onboard BepiColombo/Mercury Magnetospheric Orbiter (MMO), which performs remote and in-situ measurements of waves (electromagnetic and electrostatic). Technically, SORBET includes a plasma wave spectrometer, with two E-field inputs from the two perpendicular electric antennas and one B-field input from a search coil, in the range 2.5 kHz - 640 kHz. This frequency band includes the local gyrofrequency and plasma frequency expected on most part of the MMO orbits. SORBET also includes a higher frequency radio receiver for remote sensing in the range 500kHz-10.2MHz. Owing to its capabilities, SORBET will be able to address the following scientific objectives: High resolution mapping (˜ 30 km) of electron density and temperature in the solar wind and Hermean magnetosphere and exo-ionosphere, via the technique of Quasi-Thermal Noise (QTN) spectroscopy. It is noteworthy that the QTN technique is weakly sensitive to spacecraft potential and photoelectron perturbations, a point highly in favour of this technique at Mercury. These QTN measurements will be determinant for the dynamic modeling of the magnetosphere and will provide a fundamental input for the chemistry of cold ionized species (Na, K, O ...) in Mercury's environment. Detection and study of Hermean radio emissions, including possible cyclotron emissions (up to ˜ 10-20 kHz) from mildly energetic electrons in highly magnetized (polar?) regions, and possible synchrotron radiation (up to a few MHz?) from more energetic electrons. Monitoring of solar radio emissions up to ~10 MHz, in order to create a solar activity index from the view point of Mercury, allowing to correlate it with the Hermean magnetospheric response. We propose to further discuss these scientific objectives and to underline that such radio HF measurements are a clue for understanding the structure and dynamics (regions, boundaries, acceleration, dissipation processes ...) of the Hermean magnetosphere/exo-ionosphere system and its interaction with the solar wind.

  11. EFFECTS OF ALFVEN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

    SciTech Connect

    Zhao, G. Q.; Chen, L.; Wu, D. J.; Yan, Y. H.

    2013-06-10

    Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfven waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoff distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.

  12. ASSESSMENT OF THE IMMUNE RESPONSIVENESS OF MICE IRRADIATED WITH CONTINUOUS WAVE OR PULSE-MODULATED 425-MHZ RADIO FREQUENCY RADIATION

    EPA Science Inventory

    Groups of female BALB/C mice were irradiated with 425-MHz radio frequency (RF) radiation either continuous wave (CW) or pulse modulated (PM, 1-ms pulse width, 250 pulses/s). Mice were irradiated in a rectangular strip-transmission line at average forward powers of 78, 17.7, or 5 ...

  13. Simultaneous excitation of large-scale geomagnetic field fluctuations and plasma density irregularities by powerful radio waves

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kuo, S. P.

    1985-01-01

    The physical mechanism of thermal filamentation instability of radio waves whose frequencies can be as low as in the VLF band and as high as in the SHF band are investigated. This instability can excite large-scale magnetic and plasma density fluctuations simultaneously in the ionosphere and magnetosphere. Relevant experiments are reviewed in terms of this instability and other mechanisms.

  14. Long-term integrated radiophysical studies of the ionosphere, near space, and the propagation of radio waves from space objects

    NASA Technical Reports Server (NTRS)

    Misyura, V. A.

    1974-01-01

    The radiophysical studies reported consist of direct measurements of certain effects induced in the propagation of radio waves from space objects. From measured effects and from data on the motion and position of space objects, physical parameters of the medium and bodies are determined.

  15. Fungicidal Effects of Plasma and Radio-Wave Pre-treatments on Seeds of Grain Crops and Legumes

    NASA Astrophysics Data System (ADS)

    Filatova, Irina; Azharonok, Viktor; Shik, Alexander; Antoniuk, Alexandra; Terletskaya, Natalia

    An influence of RF plasma and RF electromagnetic field pre-treatments on level of fungal infection of some important agricultural plants has been studied. It is shown that pre-sowing plasma and radio-wave seeds treatments contribute to their germination enhancement and plant productivity improvement owing to stimulative and fungicidal effect of plasma and RF electromagnetic field irradiation.

  16. Wavelength dependence in radio-wave scattering and specular-point theory

    NASA Technical Reports Server (NTRS)

    Tyler, G. L.

    1976-01-01

    Radio-wave scattering from natural surfaces contains a strong quasispecular component that at fixed wavelengths is consistent with specular-point theory, but often has a strong wavelength dependence that is not predicted by physical optics calculations under the usual limitations of specular-point models. Wavelength dependence can be introduced by a physical approximation that preserves the specular-point assumptions with respect to the radii of curvature of a fictitious, effective scattering surface obtained by smoothing the actual surface. A uniform low-pass filter model of the scattering process yields explicit results for the effective surface roughness versus wavelength. Interpretation of experimental results from planetary surfaces indicates that the asymptotic surface height spectral densities fall at least as fast as an inverse cube of spatial frequency. Asymptotic spectral densities for Mars and portions of the lunar surface evidently decrease more rapidly.

  17. Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves

    NASA Technical Reports Server (NTRS)

    Mantas, G. P.; Lahoz, C. H.; Carlson, H. C., Jr.

    1981-01-01

    The thermal response of the nighttime F region ionosphere to local heating by HF radio waves has been observed with the incoherent scatter radar at Arecibo, Puerto Rico. The observations consist of high-resolution space and time variation of the electron temperature as a high-power HF transmitter is switched on and off with a period 240 s. As soon as the HF transmitter is turned on, the electron temperature begins to rise rapidly in a narrow altitude region near 300 km, below the F2 layer peak. The electron temperature perturbation subsequently spreads over a broader altitude region. The observations are compared with the anticipated thermal response of the ionosphere based on numerical solutions of the coupled time-dependent heat conduction equations for the electron and composite ion gases and are found to be in good agreement over the entire altitude region covered by the observations.

  18. Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuits

    E-print Network

    Balram, Krishna C; Song, Jin Dong; Srinivasan, Kartik

    2015-01-01

    The interaction of optical and mechanical modes in nanoscale optomechanical systems has been widely studied for applications ranging from sensing to quantum information science. Here, we develop a platform for cavity optomechanical circuits in which localized and interacting 1550 nm photons and 2.4 GHz phonons are combined with photonic and phononic waveguides. Working in GaAs facilitates manipulation of the localized mechanical mode either with a radio frequency field through the piezo-electric effect, or optically through the strong photoelastic effect. We use this to demonstrate a novel acoustic wave interference effect, analogous to coherent population trapping in atomic systems, in which the coherent mechanical motion induced by the electrical drive can be completely cancelled out by the optically-driven motion. The ability to manipulate cavity optomechanical systems with equal facility through either photonic or phononic channels enables new device and system architectures for signal transduction betwee...

  19. FDTD analysis of ELF radio waves propagating in the Earth-ionosphere waveguide

    NASA Astrophysics Data System (ADS)

    Marchenko, Volodymyr; Kulak, Andrzej; Mlynarczyk, Janusz

    2015-04-01

    We developed an FDTD model of electromagnetic wave propagation in the Earth-ionosphere cavity. We present the results of FDTD calculations assuming axisymmetric system with the source located at the north pole and with no dependence on azimuthal coordinate. Therefore we reduced the Maxwell equations to 2D spherical system of Maxwell equations. To model the conductivity profile of the Earth-ionosphere waveguide we used two models, namely one- and two-exponential profiles [Mushtak and Williams, 2002]. The day-night asymmetry was introduced by setting different model parameters for the north and south hemispheres. The ground was modeled as a perfect electric conductor. Also the upper boundary for the model was a perfect conductor but it was placed at a high enough altitude to make sure there is no reflection of the waves from this boundary. We obtained the results for the electric and magnetic field components of the propagating wave in the time and frequency domains and for various locations on Earth along the meridian. In the time domain we analyzed the evolution of the electric and magnetic field components of the radio wave generated by lighting for different probe position, the penetration of the ionosphere by the electromagnetic waves and the reflection of the waves on the terminator. In the frequency domain we analyzed the Schumann resonance spectra in different field components for different location in the computational space, the behavior of the Poynting vector and the wave impedance. We also calculated real and imaginary parts of the characteristic electric and magnetic altitudes for the daytime and nighttime ionosphere. The analysis in the frequency domain was performed up to 1 kHz. We compared the results of numerical calculations with our analytical model and found a reasonably good agreement between them. The results can be used in the analysis of global thunderstorm activity based on measurements of Schumann resonance spectra. Acknowledgements. This work has been supported by the National Science Centre grant 2012/04/M/ST10/00565. The numerical computations were done using the PL-Grid infrastructure.

  20. Automatic Recognition of Type III Solar Radio Bursts in STEREO/WAVES Data

    NASA Astrophysics Data System (ADS)

    Lobzin, V. V.; Cairns, I. H.; Zaslavsky, A.

    2014-12-01

    Type III radio bursts are produced near the local electron plasma frequency and/or near its harmonic by fast electrons ejected from the solar active regions and moving through the corona and solar wind. These bursts have dynamic spectra with frequency rapidly falling with time. This paper presents two new methods developed to detect type III bursts automatically in the data from High Frequency Receiver (HFR) of the STEREO/WAVES radio instrument onboard the STEREO spacecraft. The first technique is applicable to the low-frequency band (HFR-1: 125 kHz to 1.975 MHz) only. This technique can possibly be implemented in onboard satellite software aimed at preliminary detection of bursts and identification of time intervals with relatively high solar activity. In the second technique the bursts are detected in both the low-frequency band and the high-frequency band (HFR-2: 2.025 MHz to 16.025 MHz), with the computational burden being higher by 1 order of magnitude as compared with that for the first technique. Preliminary tests of the method show that for the first technique the pobability to detect is quite high, Pd L = 72% ± 3%. The performance of the second technique is considerably higher, Pd L+H = 81%±1%, while the number of false alarms does not exceed 10% for one daily spectrum.

  1. Developments in photonic and mm-wave component technology for fiber radio

    NASA Astrophysics Data System (ADS)

    Iezekiel, Stavros

    2013-01-01

    A review of photonic component technology for fiber radio applications at 60 GHz will be given. We will focus on two architectures: (i) baseband-over-fiber and (ii) RF-over-fiber. In the first approach, up-conversion to 60 GHz is performed at the picocell base stations, with data being transported over fiber, while in the second both the data and rum­ wave carrier are transported over fiber. For the baseband-over-fiber scheme, we examine techniques to improve the modulation efficiency of directly­ modulated fiber links. These are based on traveling-wave structures applied to series cascades of lasers. This approach combines the improvement in differential quantum efficiency with the ability to tailor impedance matching as required. In addition, we report on various base station transceiver architectures based on optically-controlled :tvfMIC self­ oscillating mixers, and their application to 60 GHz fiber radio. This approach allows low cost optoelectronic transceivers to be used for the baseband fiber link, whilst minimizing the impact of dispersion. For the RF-over-fiber scheme, we report on schemes for optical generation of 100 GHz. These use modulation of a Mach-Zehnder modulator at V? bias in cascade with a Mach-Zehnder driven by 1.25 Gb/s data. One of the issues in RF-over-fiber is dispersion, while reduced modulation efficiency due to the presence of the optical carrier is also problematic. We examine the use of silicon nitride micro-ring resonators for the production of optical single sideband modulation in order to combat dispersion, and for the reduction of optical carrier power in order to improve link modulation efficiency.

  2. Millimeter Wave Observations of the Core-Jet and Molecular Gas in the FR I Radio Galaxy NGC 3801

    E-print Network

    Mousumi Das; Stuart N. Vogel; Gijs A. Verdoes Kleijn; Christopher P. O'Dea; Stefi A. Baum

    2005-05-13

    We present BIMA 3 mm observations of the radio continuum source and the molecular gas disk in the radio loud Fanaroff & Riley Type I (FR I)galaxy NGC3801.We have detected a continuum source in the nucleus and determined that it has a flat millimeter-wave spectrum, suggesting that the emission is non-thermal and due to an AGN; the radio core is not evident in existing VLA observations. We also map the extended 3 mm emission from the previously known radio jets. In addition, we detect CO (1--0) emission associated with the dust disk observed in previous HST images. A velocity gradient is observed, indicating a two kpc radius rotating gas ring or disk oriented roughly perpendicular to the radio jets. The inferred molecular gas mass of the disk is $M(H_{2})=3\\times10^{8}M_{\\odot}$, about 1% of the dynamical mass. We also find a $\\sim 10^8$ M$_\\odot$ molecular gas clump not associated with the gas disk. There is evidence that this gas is associated with a merger and is infalling. This suggests that FR I type activity is related to merger activity, as is thought to be the case for FR II type radio galaxies. We also find indications that one of the radio jets is entraining gas from the infalling molecular gas.

  3. Scintillation Mathematics

    E-print Network

    Baxter, Paul D.

    and a rain gauge. COST 280 MCM4 4 #12; ' & $ % Example Italsat Trace #15; Time series of severe rain of tropospheric scintillation. #15; The data has been divided into rain and non­rain periods by using a radiometer rain effects for an observed attenuation trace. #15; In the wavelet transform, W , effects due to rain

  4. Multi-Band (K- Q- and E-Band) Multi-Tone Millimeter-Wave Frequency Synthesizer for Radio Wave Propagation Studies

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    This paper presents the design and test results of a multi-band multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). These studies would enable the design of robust multi-Gbps data rate space-to-ground satellite communication links. Lastly, the architecture for a compact multi-tone beacon transmitter, which includes a high frequency synthesizer, a polarizer, and a conical horn antenna, has been investigated for a notional CubeSat based space-to-ground radio wave propagation experiment.

  5. The apparent source size of type III radio bursts: Preliminary results by the STEREO/WAVES instruments

    NASA Astrophysics Data System (ADS)

    Krupar, V.; Maksimovic, M.; Santolik, O.; Cecconi, B.; Nguyen, Q. N.; Hoang, S.; Goetz, K.

    2010-03-01

    The S/WAVES instrument onboard the STEREO spacecraft measures electromagnetic waves in the solar wind. This unique project allows us to investigate properties of type III and type II radio bursts related to solar flares and propagation of coronal mass ejections (CMEs) in the interplanetary medium, respectively. We have focused on the High Frequency Receiver (HFR a part of the STEREO/WAVES instrument) which covers the frequency range 125 kHz~16.025 MHz. We present first results of a goniopolarimetric inversion for an extended source using the Singular Value Decomposition technique (SVD). We show a joint observation (including the WIND spacecraft) of the single type III radio burst connected with the X flare as a preliminary example of estimation of the apparent source size and its position.

  6. Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Cregg C. Yancey, Brandon E. Bear, Bernadine Akukwe, Kevin Chen, Jayce Dowell, Jonathan D. Gough, Jonah Kanner, Kenneth Obenberger, Peter Shawhan, John H. Simonetti , Gregory B. Taylor , Jr-Wei Tsai

    2016-01-01

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ˜30 s time window and ˜200-500 deg(2) sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ˜2. For some models, we also map the parameter space that may be constrained by non-detections.

  7. Multi-messenger Astronomy of Gravitational-wave Sources with Flexible Wide-area Radio Transient Surveys

    NASA Astrophysics Data System (ADS)

    Yancey, Cregg C.; Bear, Brandon E.; Akukwe, Bernadine; Chen, Kevin; Dowell, Jayce; Gough, Jonathan D.; Kanner, Jonah; Kavic, Michael; Obenberger, Kenneth; Shawhan, Peter; Simonetti, John H.; -Wei Tsai, Gregory B. Taylor, Jr.

    2015-10-01

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of GWs and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, the Low Frequency Array and the Murchison Widefield Array. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a ?30 s time window and ?200–500 deg2 sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a prompt radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of ?2. For some models, we also map the parameter space that may be constrained by non-detections.

  8. Radio-wave propagation in the non-Gaussian interstellar medium

    E-print Network

    Stanislav Boldyrev; Carl R. Gwinn

    2005-08-02

    Radio waves propagating from distant pulsars in the interstellar medium (ISM), are refracted by electron density inhomogeneities, so that the intensity of observed pulses fluctuates with time. The theory relating the observed pulse time-shapes to the electron-density correlation function has developed for 30 years, however, two puzzles have remained. First, observational scaling of pulse broadening with the pulsar distance is anomalously strong; it is consistent with the standard model only when non-uniform statistics of electron fluctuations along the line of sight are assumed. Second, the observed pulse shapes are consistent with the standard model only when the scattering material is concentrated in a narrow slab between the pulsar and the Earth. We propose that both paradoxes are resolved at once if one assumes stationary and uniform, but non-Gaussian statistics of the electron-density distribution. Such statistics must be of Levy type, and the propagating ray should exhibit a Levy flight. We propose that a natural realization of such statistics may be provided by the interstellar medium with random electron-density discontinuities. We develop a theory of wave propagation in such a non-Gaussian random medium, and demonstrate its good agreement with observations. The qualitative introduction of the approach and the resolution of the anomalous-scaling paradox was presented earlier in [PRL 91, 131101 (2003); ApJ 584, 791 (2003)].

  9. EVIDENCE FOR THE OSCILLATING TWO STREAM INSTABILITY AND SPATIAL COLLAPSE OF LANGMUIR WAVES IN A SOLAR TYPE III RADIO BURST

    SciTech Connect

    Thejappa, G.; Bergamo, M.; Papadopoulos, K.; MacDowall, R. J. E-mail: mbergamo@umd.edu E-mail: Robert.MacDowall@nasa.gov

    2012-03-15

    We present observational evidence for the oscillating two stream instability (OTSI) and spatial collapse of Langmuir waves in the source region of a solar type III radio burst. High time resolution observations from the STEREO A spacecraft show that Langmuir waves excited by the electron beam occur as isolated field structures with short durations {approx}3.2 ms and with high intensities exceeding the strong turbulence thresholds. These short duration events are identified as the envelope solitons which have collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets contain an intense peak and two sidebands, corresponding to beam-resonant Langmuir waves, and down-shifted and up-shifted daughter Langmuir waves, respectively, and low-frequency enhancements below a few hundred Hz. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI. The observed high intensities, short scale lengths, sideband spectral structures, and low-frequency enhancements strongly suggest that the OTSI and spatial collapse of Langmuir waves probably control the nonlinear beam-plasma interactions in type III radio bursts.

  10. Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys

    E-print Network

    Yancey, Cregg C; Akukwe, Bernadine; Chen, Kevin; Dowell, Jayce; Gough, Jonathan D; Kanner, Jonah; Kavic, Michael; Obenberger, Kenneth; Shawhan, Peter; Simonetti, John H; Taylor, Gregory B; Tsai, Jr-Wei

    2015-01-01

    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of gravitational waves and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, LOFAR and MWA. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a $\\usim 30$ second time window and $\\usim 200 \\mendash 500 \\punits{deg}^{2}$ sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio array...

  11. Imaging the Radio Universe

    E-print Network

    Hibbard, John

    -rays, and microwaves, etc). · Sound waves are pressure waves. Require a medium (air, water, etc.) to travel through. · Sound is created by a pressure wave moving a membrane in your ear. Your brain turns the vibration of this membrane into "sound". MediumEar Sound Radio Waves are not Sound Waves #12;You do not listen to radio waves

  12. The radio waves and thermal electrostatic noise spectroscopy (SORBET) experiment on BEPICOLOMBO/MMO/PWI: Scientific objectives and performance

    NASA Astrophysics Data System (ADS)

    Moncuquet, M.; Matsumoto, H.; Bougeret, J.-L.; Blomberg, L. G.; Issautier, K.; Kasaba, Y.; Kojima, H.; Maksimovic, M.; Meyer-Vernet, N.; Zarka, P.

    2006-01-01

    SORBET ( Spectroscopie des Ondes Radio and du Bruit Electrostatique Thermique) is a radio HF spectrometer designed for the radio and Plasma Waves Instrument onboard BepiColombo/Mercury Magnetospheric Orbiter (MMO), which performs remote and in situ measurements of waves (electromagnetic and electrostatic). Technically, SORBET includes a plasma wave spectrometer, with two E-field inputs from the two perpendicular electric antennas and one B-field input from a search coil, in the range 2.5-640 kHz. This frequency band includes the local gyrofrequency and plasma frequency expected on most part of the MMO orbits. SORBET also includes a higher frequency radio receiver for remote sensing in the range 500 kHz-10.2 MHz. Owing to its capabilities, SORBET will be able to address the following scientific objectives: High resolution mapping (˜30 km) of electron density and temperature in the solar wind and in the Hermean magnetosphere and exo-ionosphere, via the technique of Quasi-Thermal Noise (QTN) spectroscopy. These QTN measurements will be determinant for the dynamic modeling of the magnetosphere and will provide a fundamental input for the chemistry of cold ionized species (Na, K, O, …) in Mercury's environment. Detection and study of Hermean radio emissions, including possible cyclotron emissions (up to ˜10-20 kHz) from mildly energetic electrons in most highly magnetized (polar?) regions, and possible synchrotron radiation (up to a few MHz?) from more energetic electrons. Monitoring of solar radio emissions up to ˜10 MHz in order to create a solar activity index from the view point of Mercury, allowing to correlate it with the Hermean magnetospheric response. We especially discuss the capabilities of SORBET for performing the QTN spectroscopy in Mercury's magnetosphere, using the two electric dipole antennas equipping MMO, called MEFISTO and WPT.

  13. High Latitude Scintillation Monitoring at UHF with the COMMX Experiment on TACSat4

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Siefring, C. L.; Akins, K.; Nurnberger, M.

    2013-12-01

    UHF Beacon Transmissions at 253 MHz have provided high latitude scintillation monitoring from Gakona Alaska using the COMMX instrument on TACSat4. TACSat4 was constructed by the Naval Research Laboratory and was launched in September 2011 as an experimental communications satellite. Ground UHF transmissions are uplinked to TACSat4 using the 4 meter diameter antenna deployed to view the earth. These signals are coherently translated to other UHF frequency to be rebroadcast to the ground. Scintillation monitoring is achieved by taking the 401.25 MHz signals from ground DORIS beacons located in Cold Bay, Alaska; Yellowknife, Canada; Kauai, Hawaii; and Soccoro Island, Mexico. These signals are translated to 253 MHz and broadcast with the 4 meter antenna pointed to the UHF receiver located at Gakona, Alaska. The satellite antenna gain is 18 dB in this UHF band and the transmitter power is 2 Watts. The satellite is in an elliptical orbit with an inclination of 63 degrees and a perigee of 12,000 km. Doppler frequency shifts allow separation of each uplink from the ground DORIS beacons. This new scintillation monitoring system has been used to detect natural and artificial field aligned irregularity effects on the amplitude and phase of UHF carriers where typical scintillation amplitudes are 2dB or less. Using the HAARP transmitter in Alaska, TACSat4 was used to discover the artificial ionization clouds produce scintillation with as much as 16 dB and amplitude indices S4 greater than unity. This is the first demonstration of significant effects on radio scintillations using high power HF radio waves to disturb the ionosphere.

  14. On the antenna calibration of space radio instruments using the galactic background: General formulas and application to STEREO/WAVES

    NASA Astrophysics Data System (ADS)

    Zaslavsky, A.; Meyer-Vernet, N.; Hoang, S.; Maksimovic, M.; Bale, S. D.

    2011-03-01

    We present general formulas to calibrate the antennas of a space-based radio instrument using as a reference source the galactic background radiation (or any isotropic source). We apply these formulas to determine the effective length of the STEREO/WAVES antennas. The results for the monopoles are in agreement with the measurements performed on ground, and we provide new results for the XY and YZ dipoles used by the instrument. Our method also allows us to accurately determine the internal noise background of the radio receiver.

  15. Energetic electrons from solar flares and associated type 3 radio bursts from metric to hectometric wave frequencies

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1972-01-01

    Distinct Kev electron events as observed by satellites near the earth are, in general, associated with solar flares which are accompained by the emission of both metric and hectometric type 3 radio bursts. The positions of these flares are mainly on the western hemisphere of the sun. These results show that Kev electrons propagate under the control of the magnetic field in the interplanetary space and that, while propagating through this space, these electrons excite type 3 radio bursts from metric to hectometric wave frequencies. Emission characteristics of hectometric type 3 bursts are briefly considered in relation to the positions of associated flares.

  16. Thermal electrostatic noise and radio waves spectroscopy (SORBET) on BepiColombo/MMO/PWI

    NASA Astrophysics Data System (ADS)

    Moncuquet, M.; Matsumoto, H.; Bougeret, J.-L.; Blomberg, L.; Issautier, K.; Kasaba, Y.; Maksimovic, M.; Meyer-Vernet, N.; Yagitani, S.; Zarka, P.

    2003-04-01

    The SORBET experiment is a part of the radio and Plasma Waves Instrument (PWI) onboard BepiColombo/Mercury Magnetospheric Orbiter (MMO), which include remote and in-situ measurements of wave (electromagnetic and electrostatic), for studying the structure and dynamics (regions, boundaries, acceleration, dissipation processes...) of the Hermean magnetosphere/exo-ionosphere system and its interaction with the solar wind. More specific SORBET goals are: - Mapping of (cold) electron density and temperature in the solar wind and Hermean magnetosphere and exo-ionosphere, via the technique of Quasi-Thermal Noise (QTN) spectroscopy (and also analysis of Bernstein modes and upper-hybrid emissions). The quasi-thermal noise is due to the thermal motions of the particles, which produce electrostatic fluctuations. This noise is detected by any sensitive receiver at the ports of an electric antenna immersed in a plasma and can be used to measure in-situ the plasma density, temperature and bulk velocity. The basic reason is that this noise can be formally calculated as a function of both the particle velocity distributions and the antenna geometry. So, conversely, the "spectroscopy" of this noise reveals the local plasma properties. This method is routinely used on Ulysses and Wind spacecrafts in the solar wind or in planetary magnetospheres/ionospheres (Ulysses at Jupiter, Cassini at Venus, Earth and soon at Saturn). This method has the advantage of being relatively immune to spacecraft potential and photoelectrons perturbations. These measurements will provide a fundamental input for the chemistry of cold ionized species (Na...) in Mercury's environment and for the dynamic modelling of the magnetosphere. Corresponding plasma frequencies are expected to be up to 200-300 kHz. Hence the QTN spectrum should be measured up to at least ~2 max(fpe) ~ 600 kHz. -Detection and study of Hermean radio emissions, including possible cyclotron emissions (up to ~10-20 kHz) from mildly energetic electrons in most highly magnetized (polar?) regions, and possible synchrotron radiation (up to a few MHz?) from more energetic electrons. Indeed no stable radiation belts are expected, due to the weakness of Mercury's magnetic field, but intense bursts of energetic particles were measured by Mariner 10 in the magnetotail. Short storm-like events with ~1 minute duration (observed by Mariner 10), as well as Sodium aurorae, suggest an auroral activity at Mercury. Associated cyclotron emissions, due to keV electrons, would be produced near the gyrofrequency and below the plasma frequency in the surrounding solar wind, and thus be trapped inside the magnetospheric cavity. They can be detected only during relatively short crossings of the magnetosphere by MMO. -Monitoring of solar radio emissions up to ~10 MHz (type II and type III radio bursts, indicative of interplanetary transient shocks, CMEs, and energetic particle streams), in order to create a solar activity index from the view point of Mercury, allowing to correlate it with the Hermean magnetospheric response (i.e. "Space weather" at Mercury).

  17. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

    SciTech Connect

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

    2005-07-15

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

  18. Plastic scintillation dosimetry: optimal selection of scintillating fibers and scintillators.

    PubMed

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Beddar, A Sam; Roy, René; Beaulieu, Luc

    2005-07-01

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter. PMID:16121582

  19. A theory for narrow-banded radio bursts at Uranus - MHD surface waves as an energy driver

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Curtis, S. A.; Desch, M. D.; Lepping, R. P.

    1992-01-01

    A possible scenario for the generation of the narrow-banded radio bursts detected at Uranus by the Voyager 2 planetary radio astronomy experiment is described. In order to account for the emission burstiness which occurs on time scales of hundreds of milliseconds, it is proposed that ULF magnetic surface turbulence generated at the frontside magnetopause propagates down the open/closed field line boundary and mode-converts to kinetic Alfven waves (KAW) deep within the polar cusp. The oscillating KAW potentials then drive a transient electron stream that creates the bursty radio emission. To substantiate these ideas, Voyager 2 magnetometer measurements of enhanced ULF magnetic activity at the frontside magnetopause are shown. It is demonstrated analytically that such magnetic turbulence should mode-convert deep in the cusp at a radial distance of 3 RU.

  20. An analytical theory of radio-wave scattering from meteoric ionization - I. Basic equation

    NASA Astrophysics Data System (ADS)

    Pecina, P.

    2016-01-01

    We have developed an analytical theory of radio-wave scattering from ionization of meteoric origin. It is based on an integro-differential equation for the polarization vector, P, inside the meteor trail, representing an analytical solution of the set of Maxwell equations, in combination with a generalized radar equation involving an integral of the trail volume electron density, Ne, and P represented by an auxiliary vector, Q, taken over the whole trail volume. During the derivation of the final formulae, the following assumptions were applied: transversal as well as longitudinal dimensions of the meteor trail are small compared with the distances of the relevant trail point to both the transmitter and receiver and the ratio of these distances to the wavelength of the wave emitted by the radar is very large, so that the stationary-phase method can be employed for evaluation of the relevant integrals. Further, it is shown that in the case of sufficiently low electron density, Ne, corresponding to the case of underdense trails, the classical McKinley's radar equation results as a special case of the general theory. The same also applies regarding the Fresnel characteristics. Our approach is also capable of yielding solutions to the problems of the formation of Fresnel characteristics on trails having any electron density, forward scattering and scattering on trails immersed in the magnetic field. However, we have also shown that the geomagnetic field can be removed from consideration, due to its low strength. The full solution of the above integro-differential equation, valid for any electron volume densities, has been left to subsequent works dealing with this particular problem, due to its complexity.

  1. Ionospheric disturbances during November 30 to December 1, 1988. XIII - Unusual propagations of HF and VHF radio waves

    NASA Astrophysics Data System (ADS)

    Ichinose, Masaru; Kamata, Mitsuhiro

    1990-02-01

    Unusual ionospheric propagations of HF and VHF radio waves associated with a geomagnetic storm during November 30 to December 1, 1988 are investigated using ionospheric data from Japan, China, and Taiwan. The increased field strength of the Japanese frequency standard signals (2.5 MHz and 5 MHz) on the night of November 30 seems to be caused by an increased MUF and/or a scattering by the disturbed ionosphere. VHF-TV radio waves propagated from China were received at Kokubunji in Tokyo. One of the most probable mechanisms explaining this unusual VHF propagation is a one-hop-F2 propagation mode which is supported by an ionosphere having anomalously high foF2. These unusual HF and VHF propagations are attributed to an unusual ionospheric condition associated with the geomagnetic disturbances.

  2. Ionospheric absorption of radio waves on reflection by the E layer and by the shielding Es layer

    NASA Astrophysics Data System (ADS)

    Shirmammedov, M.; Boltaev, D.

    The AI absorption method was used to measure the radio wave absorption values for the normal E and the sporadic Es layers in the vicinity of Ashkhabad. The absorption values obtained for the Es layer are found to be 3-5 dB less than those obtained for the normal E layer, in good agreement with the data obtained in Rostov-on-Don, located at the latitude of Ashkhabad. The decrease in absorption for the Es layer, in comparison with the E layer, is 15-20 percent. Thus, the contribution of the D layer to the absorption of radio waves at 1.8-2.2 MHz is 80-85 percent.

  3. Comparative study of VLF radio wave phenomena from DE-1 and ISIS satellites received at Kashima, Japan

    NASA Astrophysics Data System (ADS)

    Ondoh, Tadanori; Nakamura, Yoshikatsu; Watanabe, Shigeaki; Aikyo, Kazuhiro

    1988-03-01

    A spectral analysis of two years of plasma-wave electric field data from the DE-1 satellite have been performed to study magnetospheric VLF radio wave phenomena. Chorus, narrow-band, ELF hiss, and whistler characteristics observed in the plasmasphere are found to be similar to those of the corresponding VLF emissions noted by the ISIS-1 and ISIS-2 satellites. In the low-density plasma of the high latitude magnetosphere, the upper limit frequency of the whistler-mode waves is found to be the electron plasma frequency. Observations of electrostatic bursts associated with narrow-band hiss around 1 kHz and those without whistler-mode waves were noted in low latitudes of the nightside outer radiation zone.

  4. Radio Crickets: Chirping Jets from Black Hole Binaries Entering their Gravitational Wave Inspiral

    E-print Network

    Kulkarni, Girish

    2015-01-01

    We study a novel electromagnetic signature of supermassive black hole binaries whose inspiral starts being dominated by gravitational wave (GW) emission. Recent simulations suggest that the binary's member BHs can continue to accrete gas from the circumbinary accretion disk in this phase of the binary's evolution, all the way until coalescence. If one of the binary members produces a radio jet as a result of accretion, the jet precesses along a biconical surface due to the binary's orbital motion. When the binary enters the GW phase of its evolution, the opening angle widens, the jet exhibits milliarcsecond scale wiggles, and the conical surface of jet precession is twisted due to apparant superluminal motion. The rapidly increasing orbital velocity of the binary gives the jet an appearance of a "chirp." This helical chirping morphology of the jet can be used to infer the binary parameters. For binaries with mass 10^7--10^10 Msun at redshifts z<0.5, monitoring these features in current and archival data wi...

  5. Stationary Planetary Waves in the Mars Winter Atmosphere as seen by the Radio Science Experiment MaRS on Mars Express

    NASA Astrophysics Data System (ADS)

    Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd; Tyler, Leonard G.; Hinson, David P.

    2015-11-01

    Stationary (Rossby) Waves are excited by the interaction of the zonally varying topography with the strong eastward winter jets. They lead to distinctive longitudinal temperature variations which contribute significantly to the asymmetry of the seasonal polar CO2 ice caps and are also important for the dust redistribution in the planetary atmosphere.Radio Science profiles from the Mars Express Radio Science Experiment MaRS at northern and southern high latitudes are used to gain insight into winter stationary wave structures on both hemispheres.Mars Global Surveyor (MGS) radio occultation measurements from the same season and year with their exceptionally good longitudinal and temporal coverage can be used to estimate the influence of transient eddies. Transient waves are especially important in the northern winter hemisphere.Wave number 2 stationary waves, driven by topography, are dominant in the northern winter latitudes while the wave number 1 wave is the most significant wave number during southern winter. The wave amplitudes peak around winter solstice on both hemispheres.Radio occultation measurements provide the unique opportunity to determine simultaneous measurements of temperature and geopotential height structures. Assuming geostrophic balance, these measurements can be used to determine meridional winds and eddy heat fluxes which provide further insight into the contribution of stationary waves to the heat exchange between the poles and the lower latitudes.

  6. Generation of Acoustic Gravity Waves by Periodic Radio Transmissions from a High-Power Ionospheric Heater

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Chernogor, Leonid; Rozumenko, Victor

    The Radiophysical Research Institute (Nizhny Novgorod, Russia) and Kharkiv V. N. Karazin National University (Kharkiv, Ukraine) have studied opportunities for the effective generation of acoustic gravity waves (AGWs) in 3 - 180-min period range. The excitation of such waves was conducted for the last several years using the SURA heating facility (Nizhny Novgorod). The detection of the HF-induced AGWs was carried out in the Radiophysical Observatory located near Kharkiv City at a distance of about 960 km from the SURA. A coherent radar for vertical sounding, an ionosonde, and magnetometer chains were used in our measurements. The main results are the following (see [1-5]): 1. Infrasound oscillation trains with a period of 6 min are detected during periodic SURA heater turn-on and -off. Similar oscillation trains are detected after long time pumping, during periodic transmissions with a period of 20 s, as well as after pumping turn-off. The train recordings begin 28 - 54 min after the heater turn-on or -off, and the train propagation speeds are about 300 - 570 m/s, the value of which is close to the sound speed at upper atmospheric altitudes. The amplitude of the Doppler shift frequency is of 10 - 40 mHz, which fits to the 0.1 - 0.3% electron density disturbances at ionospheric altitudes. The amplitude of the infrasound oscillations depends on the SURA mode of operation and the state of the upper atmosphere and ionosphere. 2. High-power radio transmissions stimulate the generation (or enhancement) of waves at ionospheric altitudes in the range of internal gravity wave periods. The HF-induced waves propagate with speeds of 360 - 460 m/s and produce changes in electron density with amplitudes of 2 - 3%. The generation of such periodic perturbations is more preferable with periods of 10 - 60 minutes. Their features depend significantly on the heater mode of operation. It should be stressed that perturbation intensity increases when a pumping wave frequency approaches the F _{_2} layer critical frequency. High-power periodic radio transmissions are capable of enhancing/damping natural wave perturbations generated by the solar terminator. 3. The study has demonstrated that the generation and propagation of AGWs with periods close to the natural oscillation periods of the atmosphere is possible. The duration of AGW oscillation trains does not dependent on the duration of turn-on/-off trains, but it is determined by changes in the current state of the atmosphere-ionosphere-magnetosphere system in general. The period of the AGW oscillation trains is determined by the period or semi-period of the pumping. It means that the mechanism of AGW generation in this case is distinct from the agreed-upon mechanism developed earlier. The AGWs, whose periods are 5 - 10% greater than the Brunt-Vaisala period, exhibit group velocities less than the speed of sound that is of about 80 - 160 m/s. They induce electron density perturbations of about 1.1 - 1.5%. The AGW generation has the following features. When the effective radiated power (ERP) is 50 MW or less, AGWs are not detected; they are reliably observed when the ERP is equal or larger than about 100 MW. Geomagnetic storms play a dual role in the AGW generation because they: (i) increase amplitudes of AGWs with 4 - 6-min and 8 - 12-min periods and (ii) yet enhance background oscillations. The latter hampers the identification of the HF-induced oscillations. Moderate magnetic storms do not markedly exert an influence on the amplitudes of oscillations with 13 - 17-min periods. 4. The quasi-periodic variations in the horizontal components of the geomagnetic field with 8 - 12-min periods become observable near Kharkiv 35 - 45 min after the beginning of pumping. Their speeds are 355 - 460 m/s, and they form trains 40 - 90 min in duration when the [5-min on, 5-min off] or [10-min on, 10-min off] heater timing is used. The 12 - 18-min period variations become observable 35 - 45 min after the beginning of pumping. Their speeds are 355 - 460 m/s, and they form trains 55 - 90 min in duration when the

  7. Global ionospheric effects of geomagnetic storm on May 2-3, 2010 and their influence on HF radio wave propagation

    NASA Astrophysics Data System (ADS)

    Kotova, Daria; Klimenko, Maxim; Klimenko, Vladimir; Zakharov, Veniamin

    2013-04-01

    In this work we have investigated the global ionospheric response to geomagnetic storm on May 2-3, 2010 using GSM TIP (Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere) simulation results. In the GSM TIP storm time model runs, several input parameters such as cross-polar cap potential difference and R2 FAC (Region 2 Field-Aligned Currents) varied as a function of the geomagnetic activity AE-index. Current simulation also uses the empirical model of high-energy particle precipitation by Zhang and Paxton. In this model, the energy and energy flux of precipitating electrons depend on a 3 hour Kp-index. We also have included the 30 min time delay of R2 FAC variations with respect to the variations of cross-polar cap potential difference. In addition, we use the ground-based ionosonde data for comparison our model results with observations. We present an analysis of the physical mechanisms responsible for the ionospheric effects of geomagnetic storms. The obtained simulation results are used by us as a medium for HF radio wave propagation at different latitudes in quiet conditions, and during main and recovery phase of a geomagnetic storm. To solve the problem of the radio wave propagation we used Zakharov's (I. Kant BFU) model based on geometric optics. In this model the solution of the eikonal equation for each of the two normal modes is reduced using the method of characteristics to the integration of the six ray equation system for the coordinates and momentum. All model equations of this system are solved in spherical geomagnetic coordinate system by the Runge-Kutta method. This model was tested for a plane wave in a parabolic layer. In this study, the complex refractive indices of the ordinary and extraordinary waves at ionospheric heights was calculated for the first time using the global first-principal model of the thermosphere-ionosphere system that describes the parameters of an inhomogeneous anisotropic medium during a geomagnetic storm. A comparison of the ordinary and extraordinary modes of HF radio ray paths in quiet and disturbed conditions has been done. We considered in more detail the features of the radio ray paths in the presence of F3 layer in the equatorial ionosphere, the main ionospheric trough and tongue of ionization at high latitudes. It is shown that the results obtained with use of radio propagation and GSM TIP models adequately describe HF radio ray paths in the Earth's ionosphere and can be used in applications. These investigations were carried out at financial support of Russian Foundation for Basic Research (RFBR) - Grant # 12-05-31217 and RAS Program 22.

  8. Plasma wave phenomena at interplanetary shocks observed by the Ulysses URAP experiment. [Unified Radio and Plasma Waves

    NASA Technical Reports Server (NTRS)

    Lengyel-Frey, D.; Macdowall, R. J.; Stone, R. G.; Hoang, S.; Pantellini, F.; Harvey, C.; Mangeney, A.; Kellogg, P.; Thiessen, J.; Canu, P.

    1992-01-01

    We present Ulysses URAP observations of plasma waves at seven interplanetary shocks detected between approximately 1 and 3 AU. The URAP data allows ready correlation of wave phenomena from .1 Hz to 1 MHz. Wave phenomena observed in the shock vicinity include abrupt changes in the quasi-thermal noise continuum, Langmuir wave activity, ion acoustic noise, whistler waves and low frequency electrostatic waves. We focus on the forward/reverse shock pair of May 27, 1991 to demonstrate the characteristics of the URAP data.

  9. Long-Range Transhorizon Lunar Surface Radio Wave Propagation in the Presence of a Regolith and a Sparse Exospheric Plasma

    NASA Technical Reports Server (NTRS)

    Manning, Robert M.

    2008-01-01

    Long-range, over-the-horizon (transhorizon) radio wave propagation is considered for the case of the Moon. In the event that relay satellites are not available or otherwise unwarranted for use, transhorizon communication provides for a contingency or backup option for non line-of-sight lunar surface exploration scenarios. Two potential low-frequency propagation mechanisms characteristic of the lunar landscape are the lunar regolith and the photoelectron induced plasma exosphere enveloping the Moon. Although it was hoped that the regolith would provide for a spherical waveguide which could support a trapped surface wave phenomena, it is found that, in most cases, the regolith is deleterious to long range radio wave propagation. However, the presence of the plasma of the lunar exosphere supports wave propagation and, in fact, surpasses the attenuation of the regolith. Given the models of the regolith and exosphere adopted here, it is recommended that a frequency of 1 MHz be considered for low rate data transmission along the lunar surface. It is also recommended that further research be done to capture the descriptive physics of the regolith and the exospheric plasma so that a more complete model can be obtained. This comprehensive theoretical study is based entirely on first principles and the mathematical techniques needed are developed as required; it is self-contained and should not require the use of outside resources for its understanding.

  10. Making Radio Waves: Tune in to These Tips for Getting Your Campus News on the Air.

    ERIC Educational Resources Information Center

    Stubbee, Melinda

    1993-01-01

    Radio is a relatively simple and effective way to make campus news and information available to the public. Establishing a college radio news service is not difficult, and developing a sound-bite service requires little equipment or expertise, just careful attention to quality and technique. More sophisticated systems can be developed easily. (MSE)

  11. Measurement of radio wave reflection due to temperature rising from rock salt and ice irradiated by an electron beam for an ultra-high-energy neutrino detector

    SciTech Connect

    Tanikawa, Takahiro; Chiba, Masami; Kamijo, Toshio; Yabuki, Fumiaki; Yasuda, Osamu; Akiyama, Hidetoshi; Chikashige, Yuichi; Kon, Tadashi; Shimizu, Yutaka; Utsumi, Michiaki; Fujii, Masatoshi

    2012-11-12

    An ultra-high-energy neutrino (UHE{nu}) gives temperature rise along the hadronic and electromagnetic shower when it enters into rock salt or ice. Permittivities of them arise with respect the temperatures at ionization processes of the UHE{nu} shower. It is expected by Fresnel's formula that radio wave reflects at the irregularity of the permittivity in the medium. We had found the radio wave reflection effect in rock salt. The reflection effect and long attenuation length of radio wave in rock salt and ice would yield a new UHE{nu} detection method. An experiment for ice was performed to study the reflection effect. A coaxial tube was filled with rock salt powder or ice. Open end of the coaxial tube was irradiated by a 2 MeV electron beam. Radio wave of 435 MHz was introduced to the coaxial tube. We measured the reflection wave from the open end. We found the radio wave reflection effect due to electron beam irradiation in ice as well as in rock salt.

  12. Scintillator based beta batteries

    NASA Astrophysics Data System (ADS)

    Rensing, Noa M.; Tiernan, Timothy C.; Shirwadkar, Urmila; O'Dougherty, Patrick; Freed, Sara; Hawrami, Rastgo; Squillante, Michael R.

    2013-05-01

    Some long-term, remote applications do not have access to conventional harvestable energy in the form of solar radiation (or other ambient light), wind, environmental vibration, or wave motion. Radiation Monitoring Devices, Inc. (RMD) is carrying out research to address the most challenging applications that need power for many months or years and which have undependable or no access to environmental energy. Radioisotopes are an attractive candidate for this energy source, as they can offer a very high energy density combined with a long lifetime. Both large scale nuclear power plants and radiothermal generators are based on converting nuclear energy to heat, but do not scale well to small sizes. Furthermore, thermo-mechanical power plants depend on moving parts, and RTG's suffer from low efficiency. To address the need for compact nuclear power devices, RMD is developing a novel beta battery, in which the beta emissions from a radioisotope are converted to visible light in a scintillator and then the visible light is converted to electrical power in a photodiode. By incorporating 90Sr into the scintillator SrI2 and coupling the material to a wavelength-matched solar cell, we will create a scalable, compact power source capable of supplying milliwatts to several watts of power over a period of up to 30 years. We will present the latest results of radiation damage studies and materials processing development efforts, and discuss how these factors interact to set the operating life and energy density of the device.

  13. Ionospheric scintillation studies

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Freemouw, E. J.

    1973-01-01

    The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work.

  14. Scintillators and applications thereof

    DOEpatents

    Williams, Richard T.

    2015-09-01

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  15. Scintillators and applications thereof

    SciTech Connect

    Williams, Richard T.

    2014-07-15

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  16. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

    PubMed

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet. PMID:24492645

  17. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation

    PubMed Central

    TSUDA, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10–100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50–90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10–50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet. PMID:24492645

  18. Investigation of radio astronomy image processing techniques for use in the passive millimetre-wave security screening environment

    NASA Astrophysics Data System (ADS)

    Taylor, Christopher T.; Hutchinson, Simon; Salmon, Neil A.; Wilkinson, Peter N.; Cameron, Colin D.

    2014-06-01

    Image processing techniques can be used to improve the cost-effectiveness of future interferometric Passive MilliMetre Wave (PMMW) imagers. The implementation of such techniques will allow for a reduction in the number of collecting elements whilst ensuring adequate image fidelity is maintained. Various techniques have been developed by the radio astronomy community to enhance the imaging capability of sparse interferometric arrays. The most prominent are Multi- Frequency Synthesis (MFS) and non-linear deconvolution algorithms, such as the Maximum Entropy Method (MEM) and variations of the CLEAN algorithm. This investigation focuses on the implementation of these methods in the defacto standard for radio astronomy image processing, the Common Astronomy Software Applications (CASA) package, building upon the discussion presented in Taylor et al., SPIE 8362-0F. We describe the image conversion process into a CASA suitable format, followed by a series of simulations that exploit the highlighted deconvolution and MFS algorithms assuming far-field imagery. The primary target application used for this investigation is an outdoor security scanner for soft-sided Heavy Goods Vehicles. A quantitative analysis of the effectiveness of the aforementioned image processing techniques is presented, with thoughts on the potential cost-savings such an approach could yield. Consideration is also given to how the implementation of these techniques in CASA might be adapted to operate in a near-field target environment. This may enable a much wider usability by the imaging community outside of radio astronomy and thus would be directly relevant to portal screening security systems in the microwave and millimetre wave bands.

  19. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, Stephen E. (Pinole, CA); Moses, William W. (Berkeley, CA)

    1991-01-01

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

  20. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J.

    1994-09-01

    Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

  1. Scintillator manufacture at Fermilab

    SciTech Connect

    Mellott, K.; Bross, A.; Pla-Dalmau, A.

    1998-08-01

    A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

  2. Possible radio wave precursors associated with the comet Shoemaker-Levy 9/Jupiter impacts

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Kaiser, M. L.; Desch, M. D.; Macdowall, R. J.

    1994-01-01

    We suggest that prior to its impact with Jupiter, comet Shoemaker-Levy 9 will behave as an electrical generator in the Jovian magnetosphere, converting planetary rotational energy to electrical energy via a dust/plasma interaction. This electrical energy will then be deposited in the dayside auroral region where it may drive various auroral phenomena including cyclotron radio emission. Such emission could be detected by spacecraft like Ulysses and Galileo many hours prior to the actual comet impact with the upper atmosphere. We apply the theory originally developed to explain the spokes in Saturn's rings. This theory allows us to quantify the driving potential associated with the comet and, consequently, to determine the radio power created in the auroral region. We conclude that if enough fine dust is present in the cometary system, comet-induced auroral radio emissions will reach detectable levels. This emission should be observable in the dayside hemisphere about 12-24 hours prior to each fragment impact.

  3. Prospects for GMRT to Observe Radio Waves from UHE Particles Interacting with the Moon

    E-print Network

    Sukanta Panda; Subhendra Mohanty; Padmanabhan Janardhan; Oscar Stål

    2007-08-13

    Ultra high energy (UHE) particles of cosmic origin impact the lunar regolith and produce radio signals through Askaryan effect, signals that can be detected by Earth based radio telescopes. We calculate the expected sensitivity for observation of such events at the Giant Metrewave Radio Telescope (GMRT), both for UHE cosmic rays (CR) and UHE neutrino interactions. We find that for 30 days of observation time a significant number of detectable events is expected above $10^{20}$ eV for UHECR or neutrino fluxes close to the current limits. Null detection over a period of 30 days will lower the experimental bounds on UHE particle fluxes by magnitudes competitive to both present and future experiments at the very highest energies.

  4. Determination of sporadic E radio wave propagation parameters based on vertical and oblique sounding

    NASA Astrophysics Data System (ADS)

    Sherstyukov, O. N.; Akchurin, A. D.; Sherstyukov, R. O.

    2015-09-01

    Sporadic E layer is often determined for HF radio communication. We have to deal with oblique radiowave propagation in the radio practice. The limiting frequencies at oblique propagation depend heavily on the transmitter power and the receiver sensitivity. The reason for this, as in the case of vertical propagation, is the dependence of Es reflection coefficient, ?Es (reflection loss R(dB)), on Es operation frequencies. This paper describes the characteristics of HF Es propagation in relation to foEs obtained from ionospheric vertical observations. It was found that characteristics of Es propagation depend on the type and height of the Es layer. Also the foEs diurnal variation at definite R(dB) was detected. This investigation allows improving the prediction of limiting frequencies for HF radio propagation.

  5. Violation of the coherence of radio waves induced by a cascade shower in the lunar regolith

    NASA Astrophysics Data System (ADS)

    Filonenko, A. D.

    2010-05-01

    It has been shown that small fluctuations of the refractive index of the lunar regolith owing to, e.g., a nonuniform density distribution, give rise to the loss of the coherence of a Cherenkov radio pulse induced by a cascade shower from an ultrahigh-energy particle and to a strong decrease in the spectral density of the radio signal. This can be one of the causes of why no events from ultrahigh-energy cosmic particles on the surface of the moon have been detected.

  6. Scintillation observations near the sun

    NASA Technical Reports Server (NTRS)

    Coles, W. A.; Rickett, B. J.; Scott, S. L.

    1978-01-01

    Results on the electron density spectrum, the random velocity and the mean velocity of the solar wind in the region from 5 to 100 solar radii are presented. Results are based on intensity scintillations of incoherent radio sources at different locations and different radio frequencies. The shape of the electron density irregularity spectrum is shown to be well modeled by a power law in wavenumber with a slope that abruptly steepens at higher wavenumbers. This two slope power law model is shown to have a break (defined as the wavenumber of the change of slope) that increases with decreasing distance from the Sun. The fractional random velocity is shown to be insignificant at distances of greater than 40 solar radii, but shows a steady increase with decreasing solar distance inside of 40 solar radii.

  7. Scintillation Forecasting Using NPOESS Data

    NASA Astrophysics Data System (ADS)

    Basu, B.; Retterer, J.; Demajistre, R.; de La Beaujardiere, O.; Scro, K.

    2005-12-01

    We have conducted a theoretical study of the use of NPOESS data for the forecasting of equatorial radio scintillation using knowledge of the equatorial Appleton anomaly, e.g., the peak-to-valley ratio of TEC (Total Electron Content) between the anomaly crests and the magnetic equator. The peak-to-valley ratio can be obtained from the UV (ultraviolet) imagery of the anomaly region that will be provided by the NPOESS sensors. The post-sunset enhancement of the upward drift velocity of the equatorial plasma has been shown, both theoretically and observationally, to be an important determinant of both the onset of scintillation and the strength of the anomaly. The technical approach is to run PBMOD, the AFRL low-latitude ionosphere model, with a range of post-sunset vertical drift velocities to determine the quantitative relationship between the peak-to-valley ratio and the maximum value of the pot-sunset upward drift velocity of equatorial plasma. Once the relationship is validated, it will be used to estimate the maximum value of the drift velocity from the peak-to-valley ratio, which is derived from the UV imagery data provided by NPOESS-like sensor, such as GUVI on TIMED satellite. The drift velocity will then be used in PBMOD to simulate the formation and evolution of equatorial plasma `bubbles' and calculate the distribution of the amplitude scintillation index S4. Results of the study will be discussed.

  8. Validating the use of scintillation proxies to study ionospheric scintillation over the Ugandan region

    NASA Astrophysics Data System (ADS)

    Amabayo, Emirant B.; Jurua, Edward; Cilliers, Pierre J.

    2015-06-01

    In this study, we compare the standard scintillation indices (S4 and ??) from a SCINDA receiver with scintillation proxies (S4p and | sDPR |) derived from two IGS GPS receivers. Amplitude (S4) and phase (??) scintillation data were obtained from the SCINDA installed at Makerere University (0.34°N, 32.57°E). The corresponding amplitude (S4p) and phase (| sDPR |) scintillation proxies were derived from data archived by IGS GPS receivers installed at Entebbe (0.04°N, 32.44°E) and Mbarara (0.60°S, 30.74°E). The results show that for most of the cases analysed in this study, ?? and | sDPR | are in agreement. Amplitude scintillation occurrence estimated using the S4p are fairly consistent with the standard S4, mainly between 17:00 UT and 21:00 UT, despite a few cases of over and under estimation of scintillation levels by S4p. Correlation coefficients between ?? and the | sDPR | proxy revealed positive correlation. Generally, S4p and S4 exhibits both moderate and strong positive correlation. TEC depletions associated with equatorial plasma bubbles are proposed as the cause of the observed scintillation over the region. These equatorial plasma bubbles were evident along the ray paths to satellites with PRN 2, 15, 27 and 11 as observed from MBAR and EBBE. In addition to equatorial plasma bubbles, atmospheric gravity waves with periods similar to those of large scale traveling ionospheric disturbances were also observed as one of the mechanisms for scintillation occurrence. The outcome of this study implies that GPS derived scintillation proxies can be used to quantify scintillation levels in the absence of standard scintillation data in the equatorial regions.

  9. Space-Borne Radio-Sounding Investigations Facilitated by the Virtual Wave Observatory (VWO)

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Fung, Shing F.; Bilitza,Dieter; Garcia, Leonard N.; Shao, Xi; Galkin, Ivan A.

    2011-01-01

    The goal of the Virtual Wave Observatory (VWO) is to provide userfriendly access to heliophysics wave data. While the VWO initially emphasized the vast quantity of wave data obtained from passive receivers, the VWO infrastructure can also be used to access active sounder data sets. Here we use examples from some half-million Alouette-2, ISIS-1, and ISIS-2 digital topside-sounder ionograms to demonstrate the desirability of such access to the actual ionograms for investigations of both natural and sounder-stimulated plasma-wave phenomena. By this demonstration, we wish to encourage investigators to make other valuable space-borne sounder data sets accessible via the VWO.

  10. The First Wave: The Beginnings of Radio in Canadian Distance Education

    ERIC Educational Resources Information Center

    Buck, George H.

    2006-01-01

    This article describes one of the first developments and deployment of radio for distance learning and education in Canada, beginning in the early 1920s. Anticipating a recent initiative of public-private partnerships, the impetus, infrastructure, and initial programs were provided by a large corporation. Description of the system, its purpose,…

  11. The Coherer: With Simple Demonstrations of the Generation, Propagation and Detection of Radio Waves

    ERIC Educational Resources Information Center

    Mills, Allan

    2010-01-01

    A coherer is a bistable device based on metal filings loosely confined between solid metal electrodes. This granular material normally exhibits a very high electrical resistance (tens of kilohms), but passage of the high-frequency current generated by reception of a radio signal causes it to "cohere" into a comparatively low resistance condition…

  12. Revealing the Hidden Wave: Using the Very Small Radio Telescope to Teach High School Physics

    ERIC Educational Resources Information Center

    Doherty, Michael; Fish, Vincent L.; Needles, Madeleine

    2011-01-01

    Scientists and teachers have worked together to produce teaching materials for the Very Small Radio Telescope (VSRT), an easy-to-use, low-cost apparatus that can be used in multiple laboratory experiments in high school and university physics and astronomy classes. In this article, we describe the motivation for the VSRT and several of the…

  13. Scintillator reflective layer coextrusion

    DOEpatents

    Yun, Jae-Chul (Naperville, IL); Para, Adam (St. Charles, IL)

    2001-01-01

    A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

  14. Dynamic of Langmuir and Ion-Sound Waves in Type 3 Solar Radio Sources

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The evolution of Langmuir and ion-sound waves in type 3 sources is investigated, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. The resulting prediction for the electrostatic decay threshold is consistent with the observed high-field cutoff in the Langmuir field distribution. It is shown that the conditions in the solar wind do not allow a steady state to be attained; rather, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be fast enough to saturate the growth of the parent Langmuir waves in the available interaction time. The resulting levels of product Langmuir and ion-sound waves are estimated theoretically and shown to be consistent with in situ ISEE 3 observations of type 3 events at 1 AU. Nonlinear interactions slave the growth and decay of product sound waves to that of the product Langmuir waves. The resulting probability distribution of ion-sound field strengths is predicted to have a flat tail extending to a high-field cutoff. This prediction is consistent with statistics derived here from ISEE 3 observations. Agreement is also found between the frequencies of the observed waves and predictions for the product S waves. The competing processes of nonlinear wave collapse and quasilinear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth. When wave and beam inhomogeneities are accounted for, arguments from quasi-linear relaxation yield an upper bound on the Langmuir fields that is too high to be relevant. Nor are the criteria for direct wave collapse of the beam-driven waves met, consistent with earlier simulation results that imply that this process is not responsible for saturation of the beam instability. Indeed, even if the highest observed Langmuir fields are assumed to he part of a long-wavelength 'condensate' produced via electrostatic decay, they still fall short of the relevant requirements for wave collapse. The most stringent requirement for collapse is that collapsing wave packets not be disrupted by ambient density fluctuations in the solar wind. Fields of several mV m(exp -1) extending over several hundred km would be needed to satisfy this requirement; at 1 AU such fields are rare at best.

  15. Simplification of millimeter-wave radio-over-fiber system employing heterodyning of uncorrelated optical carriers and self-homodyning of RF signal at the receiver.

    PubMed

    Islam, A H M Razibul; Bakaul, Masuduzzaman; Nirmalathas, Ampalavanapillai; Town, Graham E

    2012-02-27

    A simplified millimeter-wave (mm-wave) radio-over-fiber (RoF) system employing a combination of optical heterodyning in signal generation and radio frequency (RF) self-homodyning in data recovery process is proposed and demonstrated. Three variants of the system are considered in which two independent uncorrelated lasers with a frequency offset equal to the desired mm-wave carrier frequency are used to generate the transmitted signal. Uncorrelated phase noise in the resulting mm-wave signal after photodetection was overcome by using RF self-homodyning in the data recovery process. Theoretical analyses followed by experimental results and simulated characterizations confirm the system's performance. A key advantage of the system is that it avoids the need for high-speed electro-optic and electronic devices operating at the RF carrier frequency at both the central station and base stations. PMID:22418378

  16. Dynamics of Langmuir and ion-sound waves in type III solar radio sources

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Willes, A. J.; Cairns, I. H.

    1993-01-01

    The study traces the evolution of Langmuir and ion-sound waves in type III sources, incorporating linear growth, linear damping, and nonlinear electrostatic decay. Improved estimates are obtained for the wavenumber range of growing waves and the nonlinear coupling coefficient for the decay process. It is shown that the conditions in the solar wind do not allow a steady state to be attained; instead, bursty linear and nonlinear interactions take place, consistent with the highly inhomogeneous and impulsive waves actually observed. Nonlinear growth is found to be rapid enough to saturate the growth of the parent Langmuir waves in the available interaction time. The competing processes of nonlinear wave collapse and quasi-linear relaxation are discussed, and it is concluded that neither is responsible for the saturation of Langmuir growth.

  17. Internal wave activity in the polar atmospheric regions during 2006 - 2009 revealed by COSMIC radio occultation data

    NASA Astrophysics Data System (ADS)

    Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander; Liou, Yuei-An

    The satellite mission Formosat-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) consists of six micro-satellites, and each of them has four GPS-antennas. It was launched in April 2006, orbiting around the Earth at approximately 800 km. The primary scientific goal of the mission is to demonstrate the value of near-real-time radio occultation (RO) observations in improving operational numerical weather predictions (NWP). The goal is readily shown by assimilating the measurements of atmospheric parameters into used NWP-models. These parameters include density, temperature, pressure and relative humidity fields in the atmosphere. An analysis of their geographic and seasonal distributions is necessary to the understanding of the energy and momentum transfer and the reaction of the polar atmosphere in response to global warming. This task is especially important as the Polar Regions are very sensitive to the change in global temperature and it may be a major cause of global sea level rising. In this work, a statistical analysis of the internal gravity wave (IGW) activity in polar atmospheric regions (latitudes more than 60º) using Formosat-3/COSMIC RO temperature data collected from July 2006 to March 2009 has been performed. Geographic and seasonal distributions of the IGW potential energy (wave activity indicator) in the altitude interval from 15 to 35 km have been determined and analyzed. The obtained results show that the wave activity in the polar atmosphere is strong in winter and spring. The potential energy of IGWs in spring is largest in Antarctic atmospheric region, while it is largest in winter in Arctic region. The wave potential energy increases with altitude up to 35 km in the atmosphere of both Earth’s hemispheres. In Antarctic region, internal waves with high potential energy occur in the atmosphere over the Antarctic Peninsula. In Arctic region, a high wave activity is mainly observed over North Atlantic Ocean (Iceland) and Scandinavian Peninsula. In this work, the results of an analysis of the wave activity and factors influencing upon it in the polar stratosphere of Arctic and Antarctic have been presented and discussed. A statistical analysis of the IGW activity in Polar Regions (latitudes more than 60º) of the Earth’s atmosphere using Formosat-3/COSMIC RO temperature data collected from July 2006 to March 2009 is performed. Geographic and seasonal distributions of the IGW potential energy per unit mass (wave activity indicator) in the altitude interval from 15 to 35 km are determined and analyzed. This work was partially supported by the RFBR grant 13-02-00526-? and Program 22 of the RAS Presidium.

  18. Coordinated Radio, Electron, and Waves Experiment (CREWE) for the NASA Comet Rendezvous and Asteroid Flyby (CRAF) instrument

    NASA Technical Reports Server (NTRS)

    Scudder, Jack D.

    1992-01-01

    The Coordinated Radio, Electron, and Waves Experiment (CREWE) was designed to determine density, bulk velocity and temperature of the electrons for the NASA Comet Rendezvous and Asteroid Flyby Spacecraft, to define the MHD-SW IMF flow configuration; to clarify the role of impact ionization processes, to comment on the importance of anomalous ionization phenomena (via wave particle processes), to quantify the importance of wave turbulence in the cometary interaction, to establish the importance of photoionization via the presence of characteristic lines in a structured energy spectrum, to infer the presence and grain size of significant ambient dust column density, to search for the theoretically suggested 'impenetrable' contact surface, and to quantify the flow of heat (in the likelihood that no surface exists) that will penetrate very deep into the atmosphere supplying a good deal of heat via impact and charge exchange ionization. This final report provides an instrument description, instrument test plans, list of deliverables/schedule, flight and support equipment and software schedule, CREWE accommodation issues, resource requirements, status of major contracts, an explanation of the non-NASA funded efforts, status of EIP and IM plan, descope options, and Brinton questions.

  19. Numerical investigation of fast-wave propagation and radio-frequency sheath interaction with a shaped tokamak wall

    NASA Astrophysics Data System (ADS)

    Kohno, H.; Myra, J. R.; D'Ippolito, D. A.

    2015-07-01

    Interactions between propagating fast waves and radio-frequency (RF) sheaths in the ion cyclotron range of frequencies are numerically investigated based on a cold fluid plasma model coupled with a sheath boundary condition. In this two-dimensional study, the capability of the finite element code rfSOL, which was developed in previous numerical work, is extended to analyze self-consistent RF sheath-plasma interaction problems in a tokamak with a non-circular cross-section. It is found that a large sheath voltage is generated near the edges of the limiter-shaped deformation as a result of the conversion from fast to slow waves on the sheaths. The sheath voltage associated with this conversion is particularly significant in the localized region where the contact angle between the magnetic field line and the conducting wall varies rapidly along the curved sheath surface, which is consistent with the results in previous one-dimensional theoretical work. The dependences of the RF sheaths on various parameters in plasma such as the toroidal wavenumber, edge plasma density, and the degree of the RF wave absorption in the core region are also examined in detail.

  20. Radio Ghosts

    E-print Network

    Torsten A. Ensslin

    1999-06-11

    We investigate the possibility that patches of old radio plasma (`radio ghosts') of former radio galaxies form a second distinct phase of the inter-galactic medium (IGM), not mixed with the thermal gas. The separation of this phase from the ambient gas and its resistance against eroding turbulent forces is given by magnetic fields, which are expected to be roughly in pressure equilibrium with the surrounding medium. Since patches of this plasma are largely invisible in the radio we use the term `radio ghost' to characterize their nature. Possibilities and difficulties of different detection strategies of ghosts are discussed. These involve radio emission, cosmic microwave background (CMB) and starlight Comptonization, and Faraday rotation. Re-activation of the electron population in shock waves of cosmological structure formation, which seems to lead to the cluster radio relic phenomena. We discuss the role radio ghosts can have: They are able to store relativistic particles for cosmological times, but are also able to release them under the influence of very strong turbulence. This might happen during a major merger event of clusters of galaxies. The released relativistic proton population could produce the observed radio halos of some cluster of galaxies via hadronic reactions with the background gas leading to the production of secondary electrons and positrons. Destroyed ghosts, mixed with the IGM can help to magnetize it. Finally, the strong field strength within ghosts should have a significant impact on the propagation of extragalactic high energy cosmic rays.

  1. Interplanetary conditions during 3-kHz radio-wave detections in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Maclennan, C. G.; Gold, R. E.

    1985-01-01

    Plasma waves detected by the Voyager 1 and 2 spacecraft beyond about 12 AU that may be associated with the turbulence expected at the heliopause are interpreted in terms of the characteristics of the interplanetary medium at large heliocentric distances. The low-energy charged-particle environment in the outer heliosphere during the observations of the unusual plasma-wave signals is addressed. The particle data suggest that the outer heliosphere was unusually stable and free of transient shock and particle events for the roughly eight months during the wave observations.

  2. Broadband Meter-Wavelength Observations of Ionospheric Scintillation

    E-print Network

    Fallows, R A; McKay, D; Vierinen, J; Virtanen, I I; Postila, M; Ulich, Th; Enell, C-F; Kero, A; Iinatti, T; Lehtinen, M; Orispää, M; Raita, T; Roininen, L; Turunen, E; Brentjens, M; Ebbendorf, N; Gerbers, M; Grit, T; Gruppen, P; Meulman, H; Norden, M; de Reijer, J-P; Schoenmakers, A; Stuurwold, K

    2015-01-01

    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally these observations are relatively narrow band. With Low Frequency Array (LOFAR) technology at the Kilpisj\\"arvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a 3 octave bandwidth. ``Parabolic arcs'', which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broad-band observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250\\,MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disapp...

  3. Controlled stimulation of magnetospheric electrons by radio waves Experimental model for lightning effects

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Curtis, S. A.; Barcus, J. R.; Siefring, C. L.; Kelley, M. C.

    1983-01-01

    Magnetospheric electrons precipitated by ground-based coded very low frequency radio transmissions have been detected by rocket measurement of bremsstrahlung X-rays, caused by impact of the electrons with the upper atmosphere. The direct correlations obtained between the very low frequency signals and the X-rays demonstrate the limits of sensitivity required and indicate that this remote sensing technique would be useful for future study of very low frequency effects induced by single lightning strokes.

  4. OPENENDED CONFIGURATIONS OF RADIO TELESCOPES

    E-print Network

    Kreinovich, Vladik

    telescopes, devices that use the second observability window of radio waves. Why configurations of radioOPEN­ENDED CONFIGURATIONS OF RADIO TELESCOPES: A GEOMETRICAL ANALYSIS Vladik Kreinovich, Scott A. The quality of radio astronomical images drastically depends on where we place the radio telescopes. During

  5. OPENENDED CONFIGURATIONS OF RADIO TELESCOPES

    E-print Network

    Kreinovich, Vladik

    telescopes, devices that use the second observability window of radio waves. #12; Why configurations of radioOPEN­ENDED CONFIGURATIONS OF RADIO TELESCOPES: TOWARDS OPTIMAL DESIGN VLADIK KREINOVICH, SCOTT A, Russia ABSTRACT The quality of radio astronomical images drastically depends on where we place the radio

  6. External heating of stents by radio waves Pilot studies in rabbit aorta

    SciTech Connect

    Levitt, Adam B.; Robinson, Keith; Chronos, Nicolas A.F.; Daum, Wolfgang

    2003-09-01

    Purpose: This experiment was designed to assess the feasibility of radio frequency energy delivered by a prototype radio frequency generator inductive heating device (REVAX) positioned external to the body, for transient heating of stents after arterial implant. Methods and Materials: Twenty-one New Zealand White rabbits underwent stenting of their infrarenal aorta. Nine rabbits were stented and immediately placed in the REVAX for external stent heating with internal temperature probes in place. Twelve rabbits were stented and 3 days later either heated or placed in the generator as a sham for 20 min. The animals were terminated 28 days later. Results: The REVAX was able to heat the aortic stents in a controlled fashion; in Phase II experiments, the stent temperature was raised to 42 deg. C for 20 min. In Phase I mild necrosis was noted at the stent struts. In Phase II, necrosis and mineralization of the media was seen at the stent struts, and evidence of neointimal suppression was observed. Conclusion: This study demonstrated that external heating of stents in a blood vessel in a live animal via radio frequency energy is feasible. Further studies will be needed to assess whether any specific heating regimen might inhibit fibrocellular neointimal hyperplasia.

  7. Using IRI and GSM TIP model results as environment for HF radio wave propagation model during the geomagnetic storm occurred on September 26-29, 2011

    NASA Astrophysics Data System (ADS)

    Kotova, D. S.; Klimenko, M. V.; Klimenko, V. V.; Zakharov, V. E.; Ratovsky, K. G.; Nosikov, I. A.; Zhao, B.

    2015-11-01

    This paper analyses the geomagnetic storm on September 26-29, 2011. We compare the calculation results obtained using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) and IRI-2012 (Bilitza et al., 2014) model with ground-based ionosonde data of stations at different latitudes and longitudes. We examined physical mechanisms responsible for the formation of ionospheric effects during the main phase of geomagnetic storm that occurred at the rising phase of the 24th solar cycle. We used numerical results obtained from IRI-2012 and GSM TIP models as propagation environment for HF signals from an equatorial transmitter during quiet and disturbed conditions. We used the model of HF radio wave propagation developed in I. Kant Baltic Federal University (BFU) that is based on the geometrical optics approximation. We compared the obtained radio paths in quiet conditions and during the main and recovery storm phases and evaluated radio wave attenuation in different media models.

  8. Measurement of a Phase of a Radio Wave Reflected from Rock Salt and Ice Irradiated by an Electron Beam for Detection of Ultra-High-Energy Neutrinos

    E-print Network

    Chiba, Masami; Tanikawa, Takahiro; Yano, Hiroyuki; Yabuki, Fumiaki; Yasuda, Osamu; Chikashige, Yuichi; Kon, Tadashi; Shimizu, Yutaka; Watanabe, Souichirou; Utsumi, Michiaki; Fujii, Masatoshi

    2013-01-01

    We have found a radio-wave-reflection effect in rock salt for the detection of ultra-high energy neutrinos which are expected to be generated in Greisen, Zatsepin, and Kuzmin (GZK) processes in the universe. When an UHE neutrino interacts with rock salt or ice as a detection medium, a shower is generated. That shower is formed by hadronic and electromagnetic avalanche processes. The energy of the UHE neutrino shower converts to thermal energy through ionization processes. Consequently, the temperature rises along the shower produced by the UHE neutrino. The refractive index of the medium rises with temperature. The irregularity of the refractive index in the medium leads to a reflection of radio waves. This reflection effect combined with the long attenuation length of radio waves in rock salt and ice would yield a new method to detect UHE neutrinos. We measured the phase of the reflected radio wave under irradiation with an electron beam on ice and rock salt powder. The measured phase showed excellent consis...

  9. A study of electron density profiles in relation to ionization sources and ground-based radio wave absorption measurements, part 1

    NASA Technical Reports Server (NTRS)

    Gnanalingam, S.; Kane, J. A.

    1973-01-01

    An extensive set of ground-based measurements of the diurnal variation of medium frequency radio wave adsorption and virtual height is analyzed in terms of current understanding of the D- and lower E-region ion production and loss process. When this is done a gross discrepancy arises, the source of which is not known.

  10. Dynamics of plasma density perturbations in the upper ionosphere and the magnetosphere under the action of powerful HF radio waves

    NASA Astrophysics Data System (ADS)

    Borisov, N.; Ryabova, N.; Ruzhin, Yu.

    2015-11-01

    Dynamics of the density perturbations of the main plasma components (electrons, oxygen and hydrogen ions) in the upper ionosphere and the magnetosphere under the action of powerful HF radio waves is discussed theoretically and numerically. For finite heating pulse and different effective powers the variations of the density perturbations in time at various heights are investigated. We argue that due to collisionless damping the magnetospheric duct along the whole field line is not formed. Instead positive and negative perturbations of the main plasma components propagating with the attenuation in the magnetosphere with two different speeds are predicted. Utilization of pulsed heating provides significant information concerning plasma perturbations in the upper ionosphere and the magnetosphere.

  11. Detection of Transionospheric SuperDARN HF Waves by the Radio Receiver Instrument on the enhanced Polar Outflow Probe Satellite

    NASA Astrophysics Data System (ADS)

    Gillies, R. G.; Yau, A. W.; James, H. G.; Hussey, G. C.; McWilliams, K. A.

    2014-12-01

    The enhanced Polar Outflow Probe (ePOP) Canadian small-satellite was launched in September 2013. Included in this suite of eight scientific instruments is the Radio Receiver Instrument (RRI). The RRI has been used to measure VLF and HF radio waves from various ground and spontaneous ionospheric sources. The first dedicated ground transmission that was detected by RRI was from the Saskatoon Super Dual Auroral Radar Network (SuperDARN) radar on Nov. 7, 2013 at 14 MHz. Several other passes over the Saskatoon SuperDARN radar have been recorded since then. Ground transmissions have also been observed from other radars, such as the SPEAR, HAARP, and SURA ionospheric heaters. However, the focus of this study will be on the results obtained from the SuperDARN passes. An analysis of the signal recorded by the RRI provides estimates of signal power, Doppler shift, polarization, absolute time delay, differential mode delay, and angle of arrival. By comparing these parameters to similar parameters derived from ray tracing simulations, ionospheric electron density structures may be detected and measured. Further analysis of the results from the other ground transmitters and future SuperDARN passes will be used to refine these results.

  12. What Do Scintillations Tell Us about the Ionized ISM?

    NASA Astrophysics Data System (ADS)

    Rickett, B. J.

    2007-07-01

    I review what has been learned about the fine structure in the ionized interstellar medium from radio scintillation and scattering -- first, as it constrains the wavenumber spectrum of the electron density and second in terms of evidence from parabolic scintillation arcs for discrete structures on scales less than about 1 AU, which must be very widely distributed to account for the incidence of discrete parabolic arcs and Extreme Scattering Events.

  13. 27/10/2010 12:48AGU: Highlatitude geomagnetically induced current events observed on very low frequency radio wave receiver systems Page 1 of 2http://europa.agu.org/?view=article&uri=/journals/rs/rs1002/2009RS004215/2009RS004215.xml&t=

    E-print Network

    Ulich, Thomas

    frequency radio wave receiver systems Page 1 of 2http://europa.agu.org/?view=article&uri=/journals/rs/rs1002/2009RS004215/2009RS004215.xml&t= Keywords radio waves induced currents geomagnetic Index Terms Ionosphere Abstract Highlatitude geomagnetically induced current events observed on very low frequency radio wave

  14. Cometary kilometric radio waves and plasma waves correlated with ion pick-up effect at Comet Halley

    NASA Technical Reports Server (NTRS)

    Oya, H.; Morioka, A.; Miyake, W.; Smith, E. J.; Tsurutani, B. T.

    1985-01-01

    Bow-shock movements at Comet Halley are inferred from the discrete spectra of the cometary kilometric radiation (30-195 kHz); the observed emissions can be interpreted as being generated and propagating from the moving shock. The shock motion is possibly associated with the time variation of the solar wind and cometary outgassing. It is concluded that these plasma wave phenomena are manifestations of ion pick-up processes, which occur even in a remote region 7 million to 10 million km from the cometary nucleus.

  15. Shifting scintillator neutron detector

    DOEpatents

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

    2014-03-04

    Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

  16. Solar gravitational deflection of radio waves measured by very-long-baseline interferometry

    NASA Technical Reports Server (NTRS)

    Counselman, C. C., III; Kent, S. M.; Knight, C. A.; Shapiro, I. I.; Clark, T. A.; Hinteregger, H. F.; Rogers, A. E. E.; Whitney, A. R.

    1974-01-01

    Utilizing a four-antenna technique, simultaneous observations were made, at each end of an 845-km baseline, of the radio sources 3C279 and 3C273B, which are 10 deg apart in the sky. Differences in interferometric phases at 3.7-cm wavelength monitored near the time of the 1972 occultation of 3C279 by the sun, yielded a gravitational deflection of 0.99 plus or minus 0.03 times the value predicted by general relativity, corresponding to gamma = 0.98 plus or minus 0.06 (standard error).

  17. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, S.E.; Moses, W.W.

    1991-05-14

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses. 3 figures.

  18. The search for atmospheric waves below the clouds of Jupiter using radio wavelength observations

    NASA Astrophysics Data System (ADS)

    Cosentino, Rick; Butler, Bryan; Sault, Bob; Morales-Juberias, Raul; Simon, Amy

    2015-11-01

    We observed Jupiter at 2 cm wavelength with the VLA in early February 2015. This particular frequency is mostly sensitive to variations in ammonia opacity and probes a depth between 1 and 2 bars pressure; below the visible cloud deck at 0.7 bars. The data acquired was projected into a cartographic map of the planet following the technique of Sault et al. (2004). The horizontal resolution is ~1500 km and we have examined the map for atmospheric waves on these and larger scales. The map has revealed prominent features near 8N, in the North Equatorial Belt, where the 5 micron hotspot planetary wave feature also resides. The Great Red Spot is also prominent and has a noticeable meridional asymmetry. We will present our analysis of the spatial structure for the entire map and best fit of its wave feature spectrum.Our research is supported by NRAO and NMT.

  19. Numerical modelling of VLF radio wave propagation through earth-ionosphere waveguide and its application to sudden ionospheric disturbances

    E-print Network

    Pal, Sujay

    2015-01-01

    In this thesis, we theoretically predict the normal characteristics of Very Low Frequency (3~30 kHz) radio wave propagation through Earth-ionosphere waveguide corresponding to normal behavior of the D-region ionosphere. We took the VLF narrow band data from the receivers of Indian Centre for Space Physics (ICSP) to validate our models. Detection of sudden ionospheric disturbances (SIDs) are common to all the measurements. We apply our theoretical models to infer the D-region characteristics and to reproduce the observed VLF signal behavior corresponding to such SIDs. We develop a code based on ray theory to simulate the diurnal behavior of VLF signals over short propagation paths (2000~3000 km). The diurnal variation from this code are comparable to the variation obtained from a more general Long Wave Propagation Capability (LWPC) code which is based on mode theory approach. We simulate the observational results obtained during the Total Solar Eclipse of July 22, 2009 in India. We also report and simulate a h...

  20. Observations of electron gyroharmonic waves and the structure of the Io torus. [jupiter 1 spacecraft radio astronomy experiment

    NASA Technical Reports Server (NTRS)

    Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

    1980-01-01

    Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

  1. Generation of MSK Modulated Millimeter Wave Subcarrier for Radio Over Fiber Applications

    E-print Network

    Herczfeld, Peter

    composite crystal. By applying a digital voltage signal to the electro-optic section, MSK modulation-wave subcarrier in the optical domain and then employ an external modulator to superimpose the digital information. This two- step approach is complex and costly. In addition, in current wireless standards, continuous phase

  2. A novel scheme to implement duplex 60-GHz radio-over-fiber link with 20-GHz double-sideband optical millimeter-wave transmitted along the fiber

    NASA Astrophysics Data System (ADS)

    Ma, Jianxin; Yu, J.; Xin, Xiangjun; Yu, Chongxiu; Rao, Lan

    2009-03-01

    A duplex radio-over-fiber (RoF) link with a novel scheme to generate 60-GHz millimeter (mm)-wave using 20 GHz double sideband (DSB) optical mm-wave with signal carried only by its optical carrier is investigated. In the RoF downlink, the modulation frequency to generate the DSB optical mm-wave is reduced greatly. The theoretical analysis and numerical simulation show that this scheme cannot only eliminate the code form distortion caused by the time shifting of the sidebands, but also reduce the influence of the fading effect as the DSB optical mm-wave signal is transmitted along the fiber. Based on the scheme, the duplex RoF link with the frequency up- (down-) conversion of the down- (up-) link mm-wave signal is built and the uplink transmission performance is analyzed theoretically.

  3. Plasma instabilities in the high-latitude E region induced by high-power radio waves

    SciTech Connect

    Chaturvedi, P.K.; Ossakow, S.L. )

    1990-09-01

    The effect of a high-frequency powerful pump wave on high-latitude E region low-frequency plasma instabilities is theoretically considered. The growth rates and threshold criteria are calculated for instabilities associated with the electrojet (Farley-Buneman, gradient drift) and with higher-altitude parallel currents (ion acoustic, ion cyclotron, current convective). The results are discussed in the context of present ionospheric modification (heating) experiments.

  4. Software Defined Radio Architecture

    E-print Network

    Kranakis, Evangelos

    ) [14]. The USRP2 bridges the analog world of electromagnetic radio waves and digital world of computersChapter 2 Software Defined Radio Architecture A SDR is a real-time system. The inputs to the system are actions performed by the radio operator and data produced by active elements present in the SDR

  5. Are type III radio aurorae directly excited by electrostatic ion cyclotron waves

    SciTech Connect

    McDiarmid, D.R.; Watermann, J.; McNamara, A.G. ); Koehler, J.A.; Sofko, G.J. )

    1989-10-01

    In 1981, a network of three 50-MHz radar transmitters and two receivers were operated in the CW mode on the Canadian prairies. The echoes obtained from coherent ionospheric backscatter were divided into segments of 205 ms such that their FFT spectra yielded frequency resolution of 4.9 Hz. The spectra were subsequently averaged over 10 s. Type III spectra (narrow spectra with sub ion-acoustic Doppler shifts) were observed (often simultaneously) on radar links whose wave vector components perpendicular to the geomagnetic field were almost identical while their components parallel to the field were significantly different. From a statistical analysis of more than 300 type III spectra it is inferred that these are in general unlikely to arise from electrostatic ion cyclotron waves directly excited by an essentially linear process. Doppler shifts around 55 Hz were much more frequently observed than around 30 Hz, the occurrence of type III spectra increased with increasing magnetic aspect angle (deviation of the scatter wave vector from perpendicular to the geomagnetic field), and the mean Doppler shifts of type III spectra simultaneously on different radar links went through a minimum for aspect angles between 4{degree} and 7{degree} (depending on the assumed backscatter height). These three results disagree with theoretical expectations. The spectral width the type III echoes decreased linearly with magnetic aspect by about 2 Hz/deg.

  6. The thresholds of ionospheric plasma instabilities pumped by high-frequency radio waves at EISCAT

    NASA Astrophysics Data System (ADS)

    Bryers, C. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.

    2013-11-01

    We test the existing theories regarding the thresholds for the parametric decay instability (PDI), the oscillating two-steam instability (OTSI), and the thermal parametric instability (TPI) using the European Incoherent Scatter (EISCAT) facility's ionospheric heater. In these processes, the pump wave can couple to various electrostatic waves in the F layer ionosphere, which can be observed using the EISCAT UHF radar (PDI and OTSI) or by HF radar (TPI). On 19 October 2012, the heater power was stepped from ˜0.5 MW to ˜100 MW effective radiated power in seven steps using a 1 min on, 1 min off cycle. We use an electric field model, taking into account D region absorption, to compare theory with our observations. In all three cases, we find good agreement. In addition, the growth of striations formed during the TPI causes anomalous absorption of the heater wave, which we observe as decreased UHF ion line and plasma line backscatter power. We show evidence that heating for a prolonged period of time reduces the UHF ion line intensity throughout the experiment.

  7. Potential Spacecraft-to-Spacecraft Radio Observations with EJSM: Wave of the Future? (Invited)

    NASA Astrophysics Data System (ADS)

    Marouf, E. A.; Tortora, P.; Asmar, S. W.; Folkner, W. M.; Hinson, D.; Iess, L.; Linscott, I. R.; Lorenz, R. D.; Mueller-Wodarg, I. C.

    2010-12-01

    Future active radio observations of planetary and satellite atmospheres and surfaces could significantly benefit form the presence of two or more spacecraft in orbit around a target object. Traditionally, radio occultation and bistatic surface scattering experiments have been conducted using a single spacecraft operating in the Downlink (DL) configuration, with the spacecraft transmitting and at least one Earth-based station receiving. The configuration has the advantage of using powerful ground-based receivers for down-conversion, digitization, and digital recording of large bandwidth data for later off-line processing and analysis. It has the disadvantage of an available free-space signal-to-noise ratio (SNR) limited by the relatively small carrier power (10-20 W) a spacecraft can practically transmit. Recent technological advances in designing small-mass and small-power spacecraft-based digital receivers capable of on-board signal processing could open the door for significant performance improvement compared with the DL configuration. For example, with two spacecraft in orbit instead of one, the smaller distance D between the two spacecraft compared with the distance to Earth can boost achievable free-space SNR by one to three orders of magnitude, depending on D. In addition, richer variability in observation geometry can be captured using spacecraft-to-spacecraft (SC-to-SC) radio occultations and surface scattering. By their nature, traditional DL occultations are confined to the morning and evening terminators. Availability of on-board processing capability also opens the door for conducting Uplink (UL) occultation and bistatic observations, where very large power (> 20 kW) can be transmitted from an Earth-based station, potentially boasting achievable free-space SNR by orders of magnitude, comparable to the SC-to-SC case and much higher than the DL case. The Europa Jupiter System Mission (EJSM) will likely be the first planetary mission to benefit from the unprecedented opportunity of having two highly capable spacecraft orbiting Jupiter in concert and during the same time window. The strawman payload of the American Jupiter Europa Orbiter (JEO) and the European Jupiter Ganymede Orbiter (JGO) envisions at least one spacecraft (JGO) hosting an on-board digital receiving and processing capability. The receiver is specifically designed to allow for synergistic SC-to-SC observations, as well as Earth-to-JGO UL observations. In principle, each spacecraft can host an on-board digital receiver for rich combinations of high-performance synergistic or individual observations, depending on the opportunity. For the envisioned EJSM strawman payload and example tour, we examine achievable performance for potential observations that include SC-to-SC, UL, and DL occultations of Jupiter’s ionosphere and neutral atmosphere, the ionospheres and thin atmospheres of the large Jovian satellites, and of the tenuous Jovian Rings. We also consider potential bistatic scattering (bistatic-radar) observation opportunities of the surfaces of Europa and Ganymede.

  8. Observations of E region irregularities generated at auroral latitudes by a high-power radio wave

    NASA Technical Reports Server (NTRS)

    Djuth, F. T.; Jost, R. J.; Noble, S. T.; Gordon, W. E.; Stubbe, P.

    1985-01-01

    The initial results of a series of observations made with the high-power HF heating facility near Tromso, Norway are reported. During these experiments, attention was focused on the production of artificial geomagnetic field-aligned irregularities (AFAIs) in the auroral E region by HF waves. A mobile 46.9-MHz radar was used to diagnose the formation of AFAIs having spatial scales of 3.2 across geomagnetic field lines. The dynamic characteristics of the AFAIs are discussed within the context of current theoretical work dealing with the natural production of AFAIs in the ionosphere.

  9. Radiation hazards of radio frequency waves on the early embryonic development of Zebrafish

    NASA Astrophysics Data System (ADS)

    Harkless, Ryan; Al-Quraishi, Muntather; Vagula, Mary C.

    2014-06-01

    With the growing use of wireless devices in almost all day-to-day activities, exposure to radio-frequency radiation has become an immediate health concern. It is imperative that the effects of such radiation not only on humans, but also on other organisms be well understood. In particular, it is critical to understand if RF radiation has any bearing on the gene expression during embryonic development, as this is a crucial and delicate phase for any organism. Owing to possible effects that RF radiation may have on gene expression, it is essential to explore the carcinogenic or teratogenic properties that it may show. This study observed the effects of RF radiation emitted from a cellular telephone on the embryonic development of zebra fish. The expression of the gene shha plays a key role in the early development of the fish. This gene has homologs in humans as well as in other model organisms. Additionally, several biomarkers indicative of cell stress were examined: including lactate dehydrogenase (LDH), superoxide dismutase (SOD), and lipid peroxidation (LPO). Results show a significant decrease in the expression of shha, a significant decrease in LDH activity. There was no significant increase in SOD and LPO activity. No morphological abnormalities were observed in the developing embryos. At present, these results indicate that exposure to cell phone radiation may have a suppressive effect on expression of shha in D. rerio, though such exposure does not appear to cause morphological detriments. More trials are underway to corroborate these results.

  10. Absence of chronic effect of exposure to short-wave radio broadcast signal on salivary melatonin concentrations in dairy cattle.

    PubMed

    Stärk, K D; Krebs, T; Altpeter, E; Manz, B; Griot, C; Abelin, T

    1997-05-01

    A pilot study was conducted to investigate the influence of electromagnetic fields in the short-wave range (3-30 MHz) radio transmitter signals on salivary melatonin concentration in dairy cattle. The hypothesis to be tested was whether EMF exposure would lower salivary melatonin concentrations, and whether removal of the EMF source would be followed by higher concentration levels. For this pilot study, a controlled intervention trial was designed. Two commercial dairy herds at two farms were compared, one located at a distance of 500 m (exposed), the other at a distance of 4,000 m (unexposed) from the transmitter. At each farm, five cows were monitored with respect to their salivary melatonin concentrations over a period of ten consecutive days. Saliva samples were collected at two-hour intervals during the dark phase of the night. As an additional intervention, the short-wave transmitter was switched off during three of the ten days (off phase). The samples were analyzed using a radioimmunoassay. The average nightly field strength readings were 21-fold greater on the exposed farm (1.59 mA/m) than on the control farm (0.076 mA/m). The mean values of the two initial nights did not show a statistically significant difference between exposed and unexposed cows. Therefore, a chronic melatonin reduction effect seemed unlikely. However, on the first night of re-exposure after the transmitter had been off for three days, the difference in salivary melatonin concentration between the two farms (3.89 pg/ml, CI: 2.04, 7.41) was statistically significant, indicating a two- to seven-fold increase of melatonin concentration. Thus, a delayed acute effect of EMF on melatonin concentration cannot completely be excluded. However, results should be interpreted with caution and further trials are required in order to confirm the results. PMID:9247202

  11. Millimetre-Wave Spectrum of Isotopologues of Ethanol for Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Walters, Adam; Schäfer, Mirko; Ordu, Matthias H.; Lewen, Frank; Schlemmer, Stephan; Müller, Holger S. P.

    2015-06-01

    Complex molecules have been identified in star-forming regions and their formation is linked to the specific physical and chemical conditions there. They are suspected to form a role in the origins of life. Amongst these, ethanol is a fairly abundant molecule in warmer regions. For this reason, we have recently carried out laboratory measurements and analyses of the rotational spectra of the three mono-substituted deuterium isotopologues of ethanol (one of which, CH_2DCH_2OH, exists as two distinct conformers according to the position of the deuterium atom with respect to the molecular skeleton). Measurements were taken between 35-500 GHz, allowing accurate predictions in the range of radio telescopes. We have concentrated on the lowest energy anti conformers. The dataset was constrained for fitting with a standard Watson-S reduction Hamiltonian by rejecting transitions from high-lying states, which appear to be perturbed by the gauche states, and by averaging some small methyl torsional splits. This treatment is compatible with the needs for a first search in the interstellar medium, in particular in spectra taken by ALMA. For this purpose an appropriate set of predictions will be included on the Cologne Database for Molecular Spectroscopy. Previous results on the two mono-substituted 13C isotopologues which led to a tentative detection in Sgr B2(N) will be briefly summarized and compared with the latest measurements. The usefulness of studying different isotopologues in the interstellar medium will also be rapidly addressed. Bouchez et al, JQSRT 113 (11), pp. 1148-1154, 2012. Belloche et al. A&A 559, id.A47, 187pp., 2013.

  12. Channeling of high-power radio waves under conditions of strong anomalous absorption in the presence of an averaged electron heating source

    SciTech Connect

    Vas'kov, V. V.; Ryabova, N. A.

    2010-02-15

    Strong anomalous absorption of a high-power radio wave by small-scale plasma inhomogeneities in the Earth's ionosphere can lead to the formation of self-consistent channels (solitons) in which the wave propagates along the magnetic field, but has a soliton-like intensity distribution across the field. The structure of a cylindrical soliton as a function of the wave intensity at the soliton axis is analyzed. Averaged density perturbations leading to wave focusing were calculated using the model proposed earlier by Vas'kov and Gurevich (Geomagn. Aeron. 16, 1112 (1976)), in which an averaged electron heating source was used. It is shown that, under conditions of strong electron recombination, the radii of individual solitons do not exceed 650 m.

  13. A High-Resolution Study of Quasiperiodic Radio Emissions Observed by the Galileo Plasma Wave Instrument

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Christopher, I.; Granroth, L. J.

    2001-01-01

    We have conducted a study of quasiperiodic emission observed by the plasma wave instrument on board the Galileo spacecraft. These emissions appear as broadband bursts with dominant periods ranging from 10 min to over 40 min. For these emissions we have explicitly analyzed the high-resolution (waveform) data to determine the presence of impulsive, solitary signatures. Our investigations have indicated that the broadband bursts, as well as the background more narrowband continuum emission, are composed of a highly turbulent spectrum. Within the broadband burst, however, there are higher-frequency components present, but no impulsive electrostatic signatures. Also significantly, the broadband bursts show no low-frequency dispersion. We conclude that the bursts are consistent with a distant, electromagnetic source, probably in the near-Jupiter vicinity.

  14. Interferometric observation of over-horizon and ionospheric VHF radio waves associated with earthquakes.

    NASA Astrophysics Data System (ADS)

    Gotoh, T.; Hayakawa, M.

    2004-12-01

    Recently it has been found that the perturbations in the atmosphere and ionosphere take place in association with earthquakes (Hayakawa and Molchanov, 2002 Monograph). Fukumoto et al. (2001) have found that the over-horizon VHF waves (FM broadcasting signals) are occasionally observed prior to an earthquake, and their VHF direction finding has indicated that the reception of those over-horizon VHF signal is due to the perturbation in the atmosphere. Additionally Takano et al. (2001) have found that the TV VHF signals in the South-East Asia (like Thailand and China) are often received in Japan in possible association with earthquakes. In order to investigate the mechanism of those VHF anomalous signals, we have developed an interferometric measurement for those VHF signals to determine their direction of arrival (incident (elevation) angle and azmuthal angle (bearing)). We first describe our interferometer system, then show some preliminary observational data, and followed by the future system.

  15. Tunable Radio-Frequency Filters Using Acoustic Wave Resonators and Variable Capacitors

    NASA Astrophysics Data System (ADS)

    Tomoya Komatsu,; Ken-ya Hashimoto,; Tatsuya Omori,; Masatsune Yamaguchi,

    2010-07-01

    In this paper, we describe possible configurations for tunable filters based on RF surface or bulk acoustic wave (SAW/BAW) technologies. The frequency tuning is made possible by variable capacitors (VCs) connected to SAW/BAW resonators in the ladder-type filter configuration. First, it is shown that the passband edges can be controlled by one VC connected to each resonator. Second, it is discussed that the width and location of a passband can be controlled flexibly by two VCs connected to each resonator both in parallel and in series. Finally, the SAW filters with the proposed configuration are fabricated on a Cu-grating/15°YX-LiNbO3 substrate structure, and the tuning capability is demonstrated.

  16. A study of electron density profiles in relation to ionization sources and ground-based radio wave absorption measurements, part 2

    NASA Technical Reports Server (NTRS)

    Gnanalingam, S.; Kane, J. A.

    1975-01-01

    The D-region ion production functions are used to calculate the relationship between radio wave absorption and the flux level of X-rays in the 1-8A wavelength band. In order to bring this calculation into agreement with the empirically established relationship, it was found necessary to reduce by, a factor of about 5, the Meira nitric oxide densities below 90 km.

  17. Study of effects of radio-wave frequency radiation emitted from cellular telephones on embryonic development of danio rerio

    NASA Astrophysics Data System (ADS)

    Vagula, Mary; Harkless, Ryan

    2013-05-01

    Radio wave frequency (RF) radiation emitted from cellular telephones has become increasingly ubiquitous as a result of the popularity of these phones. With the increasing and unavoidable exposure to RF radiation a reality, it is imperative that the effects of such radiation on living tissue be well understood. In particular, it is critical to understand any effects that RF radiation may have as a carcinogen and on embryonic development, as pregnant women are not exempt from such exposure. As a model organism, zebrafish (Danio rerio) have been studied extensively, and their value in studies of gene expression cannot be overstated. This study observed the effects of RF radiation on the embryonic development of zebrafish. The expression of two genes, shha and hoxb9a, that are key to the early development of the fish was examined. Both genes have homologs in humans as well as in other model organisms. Preliminary results suggest that exposure to cell phone radiation might have an effect on the expression of shha in zebrafish embryos, causing under expression. More trials are necessary to validate these results.

  18. Investigation of the polar electrojet-current system using radio-wave heating from a ground-based facility

    SciTech Connect

    Werner, D.H.; Ferraro, A.J.; Brandt, R.G.

    1990-10-01

    The High Power Auroral Stimulation (HIPAS) heating facility has been used to modulate D region ionospheric currents at high latitudes, producing very low frequency (VLF) radio wave emissions. The behavior of these ionospheric currents can be deduced from a comprehensive study of the VLF signals received at a local field site. This Paper examines the relationship between the VLF magnetic field strength measured on the ground and the intensity of an overhead electrojet current for the purpose of enhancing communications. The mapping of the polar electrojet current from the E region down through the D region, where it can then be modulated by the heater beam, is investigated. A finite difference solution to the electrojet mapping .problem is presented in which arbitrary conductivity profiles can be specified. Results have been obtained using a simple Cowling model of the electrojet. These results indicate that for electrojets flowing between 100 and 110 km with scale sizes in excess of 100 km, the mapping of the horizontal current density can be completely characterized in terms of the Pedersen and Hall conductivities. This indicates that the mapping becomes independent of scale sizes which exceed 100 km. A promising new diagnostic technique, for studying ionospheric D region currents, has been implemented using the HIPAS facility. This technique involves high frequency (HF) beam steering for localized VLF generation in the mapped region below electrojets. Beam steering has been used to estimate the strength and current distribution of the polar electrojet, and for charting the movements of overhead currents.

  19. Uncertainty propagation through wave optics retrieval of bending angles from GPS radio occultation: Theory and simulation results

    NASA Astrophysics Data System (ADS)

    Gorbunov, Michael E.; Kirchengast, Gottfried

    2015-10-01

    The wave optical technique for bending angle retrieval in processing radio occultation observations is nowadays widely used by different data processing and assimilation groups and centers. This technique uses Fourier Integral Operators that map the observed records of the amplitude and phase into the impact parameter representation, which allows for the retrieval of bending angle as a function of impact parameter. We investigate the propagation of uncertainty in the observed amplitude and excess phase to the retrieved bending angle. We construct a simple linear approximation, where the excess phase uncertainty is mapped into the bending angle uncertainty. This results in a simple analytical expression for the final uncertainty. To verify our approximation, we perform numerical Monte Carlo simulations for three example occultation events (tropical, middle, and polar latitude profiles from an atmospheric analysis). We demonstrate that our approximation basically gives good results in all cases over the entire troposphere. Exception is the narrow area near the top of the sharp boundary layer, especially in tropics, where, due to nonlinear effects, a significant systematic error arises accompanied by increased uncertainty.

  20. Scenario Machine: fast radio bursts, short gamma-ray burst, dark energy and Laser Interferometer Gravitational-wave Observatory silence

    NASA Astrophysics Data System (ADS)

    Lipunov, V. M.; Pruzhinskaya, M. V.

    2014-05-01

    We discuss the recently reported discovery of fast radio bursts (FRBs) in the framework of the neutron star-neutron star (NS+NS) or neutron star-black hole (NS+BH) binary merger model. We concentrate on what we consider to be an issue of greatest importance: what is the NS merger rate given that the FRB rate (1/1000 yr-1 per galaxy) is inconsistent with gamma-ray burst rate as discussed by Thornton and should be significantly higher. We show that there is no discrepancy between NS merger rate and observed FRB rates in the framework of the Scenario Machine population synthesis - for a kick velocity of 100-150 km s-1 an average NS merger rate is 1/500-1/2000 yr-1 per galaxy up to z = 0.5-1. Based on the Scenario Machine NS merger rate estimates, we discuss the lack of positive detections on the ground-based interferometers, considering the Laser Interferometer Gravitational-wave Observatory.

  1. Radio Astronomy Radio astronomy

    E-print Network

    Metchev, Stanimir

    Radio Astronomy Jin Koda #12;Radio astronomy #12;Atmospheric Window #12;Centimeter radio astronomy Effelsberg 100m telescope (Germany) Green Bank 100m telescope (National Radio Astronomy Observatory;WestVirginia) #12;Centimeter radio astronomy HI 21cm line emission traces the distribution of atomic hydrogen. Dust

  2. Large scale atmospheric waves in the Venus mesosphere as seen by the VeRa Radio Science instrument on Venus Express

    NASA Astrophysics Data System (ADS)

    Tellmann, Silvia; Häusler, Bernd; Hinson, David P.; Tyler, G. Leonard; Andert, Thomas P.; Bird, Michael K.; Imamura, Takeshi; Pätzold, Martin; Remus, Stefan

    2015-04-01

    Atmospheric waves on all spatial scales play a crucial role in the redistribution of energy, momentum, and atmospheric constituent in planetary atmosphere and are thought to be involved in the development and maintenance of the atmospheric superrotation on Venus. The Venus Express Radio-Science Experiment VeRa sounded the Venus neutral atmosphere and ionosphere in Earth occultation geometry using the spacecraft radio subsystem at two coherent frequencies. Radial profiles of neutral number density, covering the altitude range 40-90 km, are then converted to vertical profiles of temperature and pressure, assuming hydrostatic equilibrium. The extensive VeRa data set enables us to study global scale atmospheric wave phenomena like thermal tides in the mesosphere and troposphere. A pronounced local time dependency of the temperature is found in the mesosphere at different altitude levels. Wave-2 structures dominate the low latitude range in the upper mesosphere while the higher latitudes show a strong wave-1 structure at the top of the cloud layer. The investigation of these wave structures provides valuable information about the energy transport in the atmosphere.

  3. Gravitational Interstellar Scintillation

    E-print Network

    Redouane Al Fakir

    2008-05-23

    Gravitation could modulate the interstellar scintillation of pulsars in a way that is analogous to refractive interstellar scintillation (RISS). While RISS occurs when a large ionized cloud crosses the pulsar line-of-sight, gravitational interstellar scintillation (GISS) occurs when a compact gravitational deflector lies very near to that line-of-sight. However, GISS differs from RISS in at least two important respects: It has a very distinctive and highly predictible time signature, and it is non-dispersive. We find two very different astronomical contexts where GISS could cause observable diffraction-pattern distortions: Highly inclined binary pulsars, and the kind of compact interstellar clouds suspected of causing extreme scattering events.

  4. Influence of an inhomogeneous structure of the high-latitude ionosphere on the long-distance propagation of high-frequency radio waves

    NASA Astrophysics Data System (ADS)

    Uryadov, V. P.; Vertogradov, G. G.; Vertogradova, E. G.

    2012-09-01

    We present the results of experimental studies of the features of long-distance propagation of high-frequency radio waves on the large-extent subauroral Magadan-Rostov-on-Don and midlatitude Khabarovsk-Rostov-on-Don and Irkutsk-Rostov-on-Don paths, which were obtained using the ionosonde-finder with a chirp output signal. Anomalous (lateral) signals with delays of about 1-2 ms with respect to a direct signal, which arrive from the azimuths 10°-20°, are observed on the Magadan-Rostov-on-Don path. The lateral signals were observed in the morning and antemeridian hours in the time interval 08:00-10:40 MSK. In the evening and night hours, the lateral signals were not observed. During magnetic activity, the amplitude of the lateral signals was greater than that observed prior to a magnetic storm by 5-10 dB. Location of the ionospheric-perturbation regions responsible for the appearance of the lateral signals was determined as ?geogr ? 69°-71°N (?magn ? 65°-66°N), and ? ? 51°-58°E. The mechanisms of the lateral-signal propagation due to lateral refraction of radio waves on patches with enhanced electron number density and due to scattering of radio waves from small-scale irregularities are considered.

  5. Advances in Composite Reflectors: From X-Ray to Radio Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Connell, S. J.; Abusafieh, A. A.; Mehle, G. V.; Sheikh, D. A.; Giles, D. C.

    2000-12-01

    In recent years, Composite Optics, Inc. (COI) has made significant advances in the use of graphite fiber reinforced composite (GFRC) materials for astronomical instrument applications. The inherent low density, high stiffness, and thermal stability makes GFRC a natural candidate for many astronomy applications. In order to reap these inherent benefits in astronomical applications, basic research has focused on material and process improvement. This has been accompanied by the design, fabrication, and test of several prototype reflectors that cover a broad wavelength spectrum of astronomical interests. The results of, and applications for, these efforts are summarized in the following list. X-Ray Carrier Shell: Innovative composite process yields accuracy and moisture stability. Demonstrated by vacuum optical test of 6" Wolter-I shell. Applicable to Con-X, etc. Lightweight Mirror Substrate for Visible Astronomy: Composite/glass hybrid design. Areal density < 15 kg/m2. Demonstrated by cryo-optical test (to 35K) of 1.6m NMSD mirror. Applicable to NGST, etc. Polishable Composite Facesheet: Glass-like coating applied to composite. Polishable by conventional methods. Multiple six-inch substrates polished to 20 angstroms. Technology will enable future 5 kg/m2 visible to UV optics. 10 kg/m2 Submillimeter Reflector: Apertures to 5m possible with economical, all-composite mirror design, diffraction limited at 80 microns. Demonstrated with cryo-optical test (to 70K) of FIRST 2-meter prototype mirror. Applicable to FIRST and other IR astronomy. Large, Ultra-Stable Optical Support Structure: Uniform and near-zero CTE over broad dimensions. Demonstrated with cryo-optical test of 2-meter FIRST prototype. Applicable to NGST, SIM, LISSA. Ground Based Radio Telescope Reflector: Low-cost, accurate, stable, durable all-composite design for support structure & reflective surface. Demonstrated via fab & test of 3m adjustable and 5m static prototypes. Applicable to LMT, ALMA, etc. These recent accomplishments represent new enabling technologies to meet the needs of numerous astronomical instrument concepts. COI will soon transition two of these technologies to production (FIRST and LMT), while continuing to further the capability of composites with on-going research. COI gratefully acknowledges the financial and technical support of NASA and the NSF for these projects.

  6. Conditioning Matrices of Liquid Scintillation Cocktails Contaminated with Tritium

    SciTech Connect

    Dianu, Magdalena

    2005-07-15

    This paper describes a viable solidification technology to convert the liquid scintillation cocktail into a stable form which minimizes the probability to release tritium in the environment.This radioactive waste type is generated by the radio-chemical analysis lab of a CANDU nuclear power plant.

  7. Interstellar Scintillation as a Cosmological Probe: Prospects and Challenges†

    NASA Astrophysics Data System (ADS)

    Koay, J. Y.; Macquart, J.-P.; Rickett, B. J.; Bignall, H. E.; Jauncey, D. L.; Lovell, J. E. J.; Reynolds, C.; Pursimo, T.; Kedziora-Chudczer, L.; Ojha, R.

    2012-04-01

    The discovery that interstellar scintillation (ISS) is suppressed for compact radio sources at z >~ 2 has enabled ISS surveys to be used as cosmological probes. We discuss briefly the potential and challenges involved in such an undertaking, based on a dual-frequency survey of ISS carried out to determine the origin of this redshift dependence.

  8. The effect of plasma inhomogeneities on (i) radio emission generation by non-gyrotropic electron beams and (ii) particle acceleration by Langmuir waves

    NASA Astrophysics Data System (ADS)

    Tsiklauri, David

    2015-04-01

    Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [1]. Here recent progress in an alternative to the plasma emission model using Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts will be presented. In particular, (i) Fourier space drift (refraction) of non-gyrotropic electron beam-generated wave packets, caused by the density gradient [1,2], (ii) parameter space investigation of numerical runs [3], (iii) concurrent generation of whistler waves [4] and a separate problem of (iv) electron acceleration by Langmuir waves in a background magnetised plasma with an increasing density profile [5] will be discussed. In all considered cases the density inhomogeneity-induced wave refraction plays a crucial role. In the case of non-gyrotropic electron beam, the wave refraction transforms the generated wave packets from standing into freely escaping EM radiation. In the case of electron acceleration by Langmuir waves, a positive density gradient in the direction of wave propagation causes a decrease in the wavenumber, and hence a higher phase velocity vph = ?/k. The k-shifted wave is then subject to absorption by a faster electron by wave-particle interaction. The overall effect is an increased number of high energy electrons in the energy spectrum. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011); http://dx.doi.org/10.1063/1.3590928 [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013); http://dx.doi.org/10.1063/1.4812453 [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012); http://dx.doi.org/10.1063/1.4768429 [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014); http://dx.doi.org/10.1063/1.4871723 [5] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 21, 012903 (2014); http://dx.doi.org/10.1063/1.4863494 This research is funded by the Leverhulme Trust Research Project Grant RPG-311

  9. Two-Way Radio in Schools (or, The Loneliness of the Long Distance Learner). An Evaluation of a High Frequency Short Wave, Two-Way Radio Trial.

    ERIC Educational Resources Information Center

    Conboy, Ian

    The Country Education Project in Victoria, Australia, tested the use of two-way radios to bring educational resources to isolated children studying correspondence courses in small rural high schools and to increase interaction among rural schools. Eight rural Victoria schools and the Secondary Correspondence School in Melbourne used two-way…

  10. Atmospheric scintillation in astronomical photometry

    NASA Astrophysics Data System (ADS)

    Osborn, J.; Föhring, D.; Dhillon, V. S.; Wilson, R. W.

    2015-09-01

    Scintillation noise due to the Earth's turbulent atmosphere can be a dominant noise source in high-precision astronomical photometry when observing bright targets from the ground. Here we describe the phenomenon of scintillation from its physical origins to its effect on photometry. We show that Young's scintillation-noise approximation used by many astronomers tends to underestimate the median scintillation noise at several major observatories around the world. We show that using median atmospheric optical turbulence profiles, which are now available for most sites, provides a better estimate of the expected scintillation noise and that real-time turbulence profiles can be used to precisely characterize the scintillation-noise component of contemporaneous photometric measurements. This will enable a better understanding and calibration of photometric noise sources and the effectiveness of scintillation correction techniques. We also provide new equations for calculating scintillation noise, including for extremely large telescopes where the scintillation noise will actually be lower than previously thought. These equations highlight the fact that scintillation noise and shot noise have the same dependence on exposure time and so if an observation is scintillation limited, it will be scintillation limited for all exposure times. The ratio of scintillation noise to shot noise is also only weakly dependent on telescope diameter and so a bigger telescope may not yield a reduction in fractional scintillation noise.

  11. N V Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) yesterday, today, tomorrow

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. D.

    2015-06-01

    This paper describes the basic and applied research rationale for the organization of IZMIRAN and provides insight into the 75 years of the Institute's activities and development. Historically, early magnetic measurements in Russia were developed largely to meet the Navy's navigation needs and were, more generally, stimulated by the Peter the Great decrees and by the foundation of the St. Petersburg Academy of Sciences in 1724. The paper examines the roles of the early Academicians in developing geomagnetism and making magnetic measurements a common practice in Russia. The need for stable radio communications prompted ionospheric and radio wave propagation research. The advent of the space era and the 1957-1958 International Geophysical Year Project greatly impacted the development of IZMIRAN and spurred the creation of a number of geophysical research institutes throughout the country. Currently, the research topics at IZMIRAN range widely from geomagnetism to solar-terrestrial physics to the ionosphere and radio wave propagation, and its primary application areas are the study and forecast of space weather, an increasingly important determining factor in ever-expanding ground- and space-based technologies (space navigation and communications, space activities, etc.).

  12. OPEN-ENDED CONFIGURATIONS OF RADIO TELESCOPES

    E-print Network

    Kreinovich, Vladik

    radio telescopes, devices that use the second observability window of radio waves. Why configurationsOPEN-ENDED CONFIGURATIONS OF RADIO TELESCOPES: A GEOMETRICAL ANALYSIS Vladik Kreinovich, Scott A. The quality of radio astronomical images drastically depends on where we place the radio telescopes. During

  13. Laboratory Studies on the Removal of Radon-Born Lead from KamLAND's Organic Liquid Scintillator

    E-print Network

    G. Keefer; C. Grant; A. Piepke; T. Ebihara; H. Ikeda; Y. Kishimoto; Y. Kibe; Y. Koseki; M. Ogawa; J. Shirai; S. Takeuchi; C. Mauger; C. Zhang; G. Schweitzer; B. E. Berger; S. Dazeley; M. P. Decowski; J. A. Detwiler; Z. Djurcic; D. A. Dwyer; Y. Efremenko; S. Enomoto; S. J. Freedman; B. K. Fujikawa; K. Furuno; A. Gando; Y. Gando; G. Gratta; S. Hatakeyama; K. M. Heeger; L. Hsu; K. Ichimura; K. Inoue; T. Iwamoto; Y. Kamyshkov; H. J. Karwowski; M. Koga; A. Kozlov; C. E. Lane; J. G. Learned; J. Maricic; D. M. Marko; S. Matsuno; D. McKee; R. D. McKeown; T. Miletic; T. Mitsui; M. Motoki; K. Nakajima; K. Nakajima; K. Nakamura; T. O'Donnell; H. Ogawa; F. Piquemal; J. -S. Ricol; I. Shimizu; F. Suekane; A. Suzuki; R. Svoboda; O. Tajima; Y. Takemoto; K. Tamae; K. Tolich; W. Tornow; Hideki Watanabe; Hiroko Watanabe; L. A. Winslow; S. Yoshida; for the KamLAND Collaboration

    2013-12-03

    The removal of radioactivity from liquid scintillator has been studied in preparation of a low background phase of KamLAND. This paper describes the methods and techniques developed to measure and efficiently extract radon decay products from liquid scintillator. We report the radio-isotope reduction factors obtained when applying various extraction methods. During this study, distillation was identified as the most efficient method for removing radon daughters from liquid scintillator.

  14. Radio Galaxies.

    ERIC Educational Resources Information Center

    Downes, Ann

    1986-01-01

    Provides background information on radio galaxies. Topic areas addressed include: what produces the radio emission; radio telescopes; locating radio galaxies; how distances to radio galaxies are found; physics of radio galaxies; computer simulations of radio galaxies; and the evolution of radio galaxies with cosmic time. (JN)

  15. Locating Radio Noise from Sprites

    NASA Astrophysics Data System (ADS)

    Fullekrug, M.; Mezentsev, A.; Watson, R.; Gaffet, S.; Astin, I.; Evans, A.

    2014-12-01

    Sprites are composed of individual streamer discharges (e.g., Pasko, 2010) which split into exponentially growing streamer tips (McHarg et al., 2010). The acceleration of the electrons to a few eV results in the radiation of a small amount of electromagnetic energy. The incoherent superposition of many streamers causes the low frequency radio noise from sprites near ~40 km height (Qin et al., 2012). The presence of this theoretically predicted radiation was recently confirmed by low frequency radio noise measurements during dancing sprites with a very sensitive radio receiver (Fullekrug et al., 2013). To locate the radio noise from sprites in the sky, an interferometric network of low frequency radio receivers was developed (Mezentsev and Fullekrug, JGR, 2013). The key parameter for the interferometric signal processing is the frequency dependent wave propagation velocity of the radio waves within the Earth's atmosphere. This wave propagation velocity is determined by the wave number vector which needs to be inferred from the measurements. Here we adapt and subsequently apply array analyses which have been developed for seismic and infrasound arrays to determine the horizontal wave number vectors of ~20-24 kHz radio waves measured with an array of ten radio receivers distributed over an area of ~1 km × 1 km. It is found that the horizontal slowness of ~20-24 kHz radio waves ranges from ~2.7 ns/m to ~4.1 ns/m depending on the arrival azimuth of the radio wave. For comparison, an electromagnetic wave in vacuum has a slowness of ~3.34 ns/m. A larger slowness indicates an apparent velocity which is smaller than the speed of light and a smaller slowness indicates that the radio wave arrives at the array from an elevation angle. The observed variability of the observed slowness almost certainly results from the distance dependent superposition of the transverse electric and magnetic TEn and TMn radio wave propagation modes.

  16. MILLISECOND PULSAR SCINTILLATION STUDIES WITH LOFAR: INITIAL RESULTS

    SciTech Connect

    Archibald, Anne M.; Kondratiev, Vladislav I.; Hessels, Jason W. T.; Stinebring, Daniel R. E-mail: kondratiev@astron.nl E-mail: dan.stinebring@oberlin.edu

    2014-08-01

    High-precision timing of millisecond pulsars (MSPs) over years to decades is a promising technique for direct detection of gravitational waves at nanohertz frequencies. Time-variable, multi-path scattering in the interstellar medium is a significant source of noise for this detector, particularly as timing precision approaches 10 ns or better for MSPs in the pulsar timing array. For many MSPs, the scattering delay above 1 GHz is at the limit of detectability; therefore, we study it at lower frequencies. Using the LOw-Frequency ARray (LOFAR) radio telescope, we have analyzed short (5-20 minutes) observations of 3 MSPs in order to estimate the scattering delay at 110-190 MHz, where the number of scintles is large and, hence, the statistical uncertainty in the scattering delay is small. We used cyclic spectroscopy, still relatively novel in radio astronomy, on baseband-sampled data to achieve unprecedented frequency resolution while retaining adequate pulse-phase resolution. We detected scintillation structure in the spectra of the MSPs PSR B1257+12, PSR J1810+1744, and PSR J2317+1439 with diffractive bandwidths of 6 ± 3, 2.0 ± 0.3, and ?7 kHz, respectively, where the estimate for PSR J2317+1439 is reliable to about a factor of two. For the brightest of the three pulsars, PSR J1810+1744, we found that the diffractive bandwidth has a power-law behavior ??{sub d}??{sup ?}, where ? is the observing frequency and ? = 4.5 ± 0.5, consistent with a Kolmogorov inhomogeneity spectrum. We conclude that this technique holds promise for monitoring the scattering delay of MSPs with LOFAR and other high-sensitivity, low-frequency arrays like the low-frequency component of the Square Kilometre Array.

  17. Radio-telemetry equipment and applications for carnivores

    E-print Network

    Schweik, Charles M.

    by use of radio waves. Most commonly, biologists use radio waves #12;that are categorized in the spectral7 Radio-telemetry equipment and applications for carnivores Mark R. Fuller and Todd K. Fuller Radio goals for this chapter are to provide basic information about radio-telemetry equipment and procedures

  18. Interplanetary plasma scintillation parameters measurements retrieved from the spacecraft observations.

    NASA Astrophysics Data System (ADS)

    Molera Calvés, Guifré; Pogrebenko, S. V.; Wagner, J.; Maccaferri, G.; Colucci, G.; Kronschnabl, G.; Scilliro, F.; Bianco, G.; Pérez Ayúcar, M.; Cosmovici, C. B.

    2010-05-01

    Measurement of the Interplanetary Scintillations (IPS) of radio signals propagating through the plasma in the Solar System by the radio astronomical instruments is a powerful tool to characterise and study the spatial and temporal variation of the electron density in the Solar wind. Several techniques based on the observation of natural and artificial radio sources have been developed during the last 50 years. Here we report our results of the IPS parameters measurement based on the multi-station observations of the planetary mission spacecraft. The ESA Venus Express spacecraft was observed at X-band (8.4 GHz) by several European VLBI stations - Metsähovi Radio Observatory (Aalto University , FI), Medicina (INAF-RA, IT), Matera (ASI, IT), Wettzell (BKG, DE), Noto (INAF-IRA, IT) and Yebes (OAN-IGN, ES) during a 2008-2010 campaign in a framework of the PRIDE (Planetary Radio Interferometry and Doppler Experiments) project as a preparatory stage for the European Radio Astronomy VLBI facilities participation in the planned ESA planetary missions (EJSM, TESM, EVE and others). Observational data were processed at Metsähovi Radio Observatory with the on-purpose developed high performance, ultra-high spectral resolution and spacecraft tracking capable software spectrometer-correlator and analysed at the Joint Institute for VLBI in Europe (JIVE, NL). High quality of acquired and analysed data enables us to study and define several parameters of the S/C signal and accompanying "ranging" tones with milli-Hz accuracy, among which the phase fluctuations of the spacecraft signal carrier line can be used to characterise the interplanetary plasma density fluctuations along the signal propagation line at different spatial and temporal scales at different Solar elongations and which exhibits a near-Kolmogorov spectrum. Such essential parameters as the phase scintillation index and bandwidth of scintillations and their dependence on the solar elongation, distance to the target, positions of the source in the Solar system and Solar activity index were retrieved from our measurements and are reported. This study is focused on the technique of the measurements and data analysis, leaving the physical interpretation of the measurement results to the upcoming studies when more observational data is collected. Our measurements of the phase scintillations from the sources within the Solar system are complementary to the classical measurements of the power level scintillations of signals from the natural radio sources. The results presented in this paper are promising and observations will continue during 2010.

  19. Polysiloxane scintillator composition

    DOEpatents

    Walker, James K. (Gainesville, FL)

    1992-01-01

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  20. Polysiloxane scintillator composition

    DOEpatents

    Walker, J.K.

    1992-05-05

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  1. Boron loaded scintillator

    SciTech Connect

    Bell, Zane William; Brown, Gilbert Morris; Maya, Leon; Sloop, Jr., Frederick Victor; Sloop, Jr., Frederick Victor

    2009-10-20

    A scintillating composition for detecting neutrons and other radiation comprises a phenyl containing silicone rubber with carborane units and at least one phosphor molecule. The carbonate units can either be a carborane molecule dispersed in the rubber with the aid of a compatibilization agent or can be covalently bound to the silicone.

  2. Scintillator Waveguide For Sensing Radiation

    DOEpatents

    Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder; Paul L. (Richland, WA)

    2003-04-22

    The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

  3. Scintillator requirements for medical imaging

    SciTech Connect

    Moses, William W.

    1999-09-01

    Scintillating materials are used in a variety of medical imaging devices. This paper presents a description of four medical imaging modalities that make extensive use of scintillators: planar x-ray imaging, x-ray computed tomography (x-ray CT), SPECT (single photon emission computed tomography) and PET (positron emission tomography). The discussion concentrates on a description of the underlying physical principles by which the four modalities operate. The scintillator requirements for these systems are enumerated and the compromises that are made in order to maximize imaging performance utilizing existing scintillating materials are discussed, as is the potential for improving imaging performance by improving scintillator properties.

  4. Signatures and Characteristics of Internal Gravity Waves in the Venus' and Mars' Atmospheres as Revealed by the Radio Occultation Temperature Data Analysis

    NASA Astrophysics Data System (ADS)

    Gubenko, Vladimir; Pavelyev, Alexander; Andreev, Vitali; Salimzyanov, Rishat; Pavelyev, Alexey

    2012-07-01

    It is well known that internal gravity waves (IGWs) affect the structure and mean circulation of the Earth' middle and upper atmosphere by transporting energy and horizontal momentum upward from the lower atmosphere. The IGWs modulate the background atmospheric structure, producing a periodic pattern of spatial and temporal variations in the wind velocity, temperature and density. Similar effects are anticipated for the Venus and Mars since IGWs are a characteristic of stably stratified atmosphere. For instance, Yakovlev et al. (1991) and Gubenko et al. (2008a) used the radio occultation (RO) data from Venera 15 and 16 missions to investigate the thermal structure and layering of the Venus' middle atmosphere. They noted that a wavelike periodic structure commonly appears in retrieved vertical profiles at altitudes above 60 km in the atmosphere where the static stability is large. Through comparisons between Magellan RO observations in the Venus' atmosphere, Hinson and Jenkins (1995) have demonstrated that small scale variations in retrieved temperature profiles at altitudes from 60 to 90 km are caused by a spectrum of vertical propagating IGWs. Temperature profiles from the Mars Global Surveyor (MGS) measurements reveal vertical wavelike structures assumed to be atmospheric IGWs in the Mars' lower atmosphere (Creasey et al., 2006). The very large IGW amplitudes inferred from MGS RO data imply a very significant role for IGWs in the atmospheric dynamics of Mars as well. There is one general problem inherent to all measurements of IGWs. Observed wavelike variations may alternatively be caused by the IGWs, turbulence or persistent layers in the atmosphere, and it is necessary to have an IGW identification criterion for the correct interpretation of obtained results. In this context, we have developed an original method for the determination of internal gravity wave parameters from a single vertical temperature profile measurement in a planetary atmosphere (Gubenko et al., 2008b, 2011). This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, the analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitude thresholds of the wave temperature field and on the linear IGW saturation theory in which amplitude thresholds are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal wave reaches the shear instability limit, energy is assumed to be dissipated in such a way that the amplitude is maintained at the instability limit as the wave propagates upwards. An application of the developed method to the RO temperature data has given the possibility to identify the IGWs in the Venus' and Mars' atmospheres and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal perturbations of the wind velocity, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy, vertical fluxes of the wave energy and horizontal momentum. The obtained results of internal wave studies in the Venus' and Mars' atmospheres deduced from the Magellan and MGS RO temperature profiles are presented and discussed. This work was partially supported by the RFBR Grant (No. 10-02-01015-a) and program OFN-15 of the Russian Academy of Sciences. References Creasey, J. E., Forbes, J. M., and Hinson, D. P.: Global and seasonal distribution of gravity wave activity in Mars' lower atmosphere derived from MGS radio occultation data, Geophys. Res. Lett., 33, L01803, doi: 10.1029/2005GL024037, 2006. Gubenko, V.N., Andreev, V.E., and Pavelyev, A.G.: Detection of layering in the upper cloud layer of Venus northern polar atmosphere observed from radio occultation data, J. Geophys. Res., 113, E03001, doi:10.1029/2007

  5. Measurements of an Antenna Surface for a Millimeter-Wave Space Radio Telescope. II. Metal Mesh Surface for Large Deployable Reflector

    NASA Astrophysics Data System (ADS)

    Kamegai, Kazuhisa; Tsuboi, Masato

    2013-02-01

    Large deployable antennas with a mesh surface woven by fine metal wires are an important technology for communications satellites and space radio telescopes. However, it is difficult to make metal mesh surfaces with sufficient radio-frequency (RF) performance for frequencies higher than millimeter waves. In this paper, we present the RF performance of metal mesh surfaces at 43 GHz. For this purpose, we developed an apparatus to measure the reflection coefficient, transmission coefficient, and radiative coefficient of the mesh surface. The reflection coefficient increases as a function of the metal mesh surface tension, whereas the radiative coefficient decreases. The anisotropic aspects of the reflection coefficient and the radiative coefficient are also clearly seen. They depend on the front and back sides of the metal mesh surface and the rotation angle. The transmission coefficient was measured to be almost constant. The measured radiative coefficients and transmission coefficients would cause significant degradation of the system noise temperature. In addition, we carried out an astronomical observation of a well-known SiO maser source, R Cas, by using a metal mesh mirror on the NRO 45-m radio telescope Coudé system. The metal mesh mirror considerably increases the system noise temperature, and slightly decreases the peak antenna temperature. These results are consistent with laboratory measurements.

  6. Radio Interferometric Geolocation Miklos Maroti

    E-print Network

    Maróti, Miklós

    Radio Interferometric Geolocation Mikl´os Mar´oti P´eter V¨olgyesi Sebesty´en D´ora Branislav.kusy, akos.ledeczi}@vanderbilt.edu ABSTRACT We present a novel radio interference based sensor local- ization method for wireless sensor networks. The technique relies on a pair of nodes emitting radio waves

  7. Comparison of the effect of high-latitude and equatorial ionospheric scintillation on GPS signals during the maximum of solar cycle 24

    NASA Astrophysics Data System (ADS)

    Jiao, Yu; Morton, Yu T.

    2015-09-01

    Radio signal scintillation caused by electron density irregularities in the ionosphere affects the accuracy and integrity of Global Navigation Satellite Systems, especially in the equatorial and high-latitude regions during solar maxima. Scintillation in these two regions, nevertheless, is usually influenced by different factors and thus has different characteristics that cause different effects on GNSS signals. This paper compares the characteristics of high-latitude and equatorial scintillation using multifrequency GPS scintillation data collected at Gakona, Alaska, Jicamarca, Peru, and Ascension Island during the 24th solar maximum. Several statistical distributions are established based on the data to characterize the intensity, duration, and occurrence frequency of scintillation. Results show that scintillation in the equatorial region is generally more severe and longer lasting, while high-latitude scintillation is, in general, more moderate and usually dominated by phase fluctuations. Results also reveal the different impacts of solar activity, geomagnetic activity, and seasons on scintillation in different geographic locations.

  8. Background radio-frequency radiation and its impact on radio astronomy Michelle C. Storey, Bruce MacA Thomas and John M. Sarkissian

    E-print Network

    Sarkissian, John M.

    of the radio-frequency background levels as they use the most sensitive radio-wave receivers in the world to study the sky at radio wavelengths. Radio waves can give us information about astronomical phenomena astronomy telescopes are the most sensitive radio-wave receivers in the world. For example, a mobile phone

  9. Wave represents displacement Wave represents pressure Source -Sound Waves

    E-print Network

    Colorado at Boulder, University of

    Wave represents displacement Wave represents pressure Source - Sound Waves Distance between crests students connect physics to the real world. The representation of sound in the Sound Waves simulation. The Sound Waves simulation becomes the source of an analogical mapping to Radio Waves. Concepts

  10. Subionospheric VLF/LF radio waves propagation characteristics before, during and after the Sofia, Bulgaria Mw=5.6 earthquake occurred on 22 May 2012

    NASA Astrophysics Data System (ADS)

    Moldovan, Iren Adelina; Emilian Toader, Victorin; Nenovski, Petko; Biagi, Pier Francesco; Maggipinto, Tommaso; Septimiu Moldovan, Adrian; Ionescu, Constantin

    2013-04-01

    In 2009, INFREP, a network of VLF (20-60 kHz) and LF (150-300 kHz) radio receivers, was put into operation in Europe having as principal goal, the study of disturbances produced by the earthquakes on the propagation properties of these signals. On May 22nd, 2012 an earthquake with Mw=567 occurred in Bulgaria, near Sofia, inside the "sensitive" area of the INFREP VLF/LF electromagnetic network. The data collected on different frequencies, during April-May 2012 were studied using different methods of analysis: daily correlation methods, spectral approaches and terminator time techniques, in order to find out possible connections between the seismic activity and the subionospheric propagation properties of radio waves. The studies were performed with the help of a specially designed LabVIEW application, which accesses the VLF/LF receiver through internet. This program opens the receiver's web-page and automatically retrieves the list of data files to synchronize the user-side data with the receiver's data. Missing zipped files are also automatically downloaded. The application performs primary, statistical correlation and spectral analysis, appends daily files into monthly and annual files and performs 3D colour-coded maps with graphic representations of VLF and LF signals' intensities versus the minute-of-the-day and the day-of-the-month, facilitating a near real-time observation of VLF and LF electromagnetic waves' propagation. Another feature of the software is the correlation of the daily recorded files for the studied frequencies by overlaying the 24 hours radio activity and taking into account the sunrise and sunset. Data are individually processed (spectral power, correlations, differentiation, filtered using bandpass, lowpass, highpass). JTFA spectrograms (Cone-Shaped Distribution CSD, Gabor, Wavelet, short-time Fourier transform STFT, Wigner-Ville Distribution WVD, Choi-Williams Distribution CWD) are used, too.

  11. Whistlers, helicons, and lower hybrid waves: The physics of radio frequency wave propagation and absorption for current drive via Landau damping

    NASA Astrophysics Data System (ADS)

    Pinsker, R. I.

    2015-09-01

    This introductory-level tutorial article describes the application of plasma waves in the lower hybrid range of frequencies (LHRF) for current drive in tokamaks. Wave damping mechanisms in a nearly collisionless hot magnetized plasma are briefly described, and the connections between the properties of the damping mechanisms and the optimal choices of wave properties (mode, frequency, wavelength) are explored. The two wave modes available for current drive in the LHRF are described and compared. The terms applied to these waves in different applications of plasma physics are elucidated. The character of the ray paths of these waves in the LHRF is illustrated in slab and toroidal geometries. Applications of these ideas to experiments in the DIII-D tokamak are discussed.

  12. Experimental investigation of ULF/VLF radio wave generation and propagation in the upper atmosphere and ionosphere during EISCAT heating experiment in 2012

    NASA Astrophysics Data System (ADS)

    Ryakhovskiy, Iliya; Gavrilov, Boris; Zetzer, Julius; Rietveld, Michael; Poklad, Yuriy; Blagoveshchenskaya, Nataly

    Powerful high frequency radio waves transmitted from high-power HF heating facilities modify the ionospheric plasma. The X-mode HF pump wave generates strong small-scale artificial field aligned irregularities in the F region of the ionosphere when the heater frequency is near or above the critical frequency of F2 layer [Blagoveshchenskaya et al]. One of the tasks of the Russian EISCAT heating campaign in February 2012 was an investigation of the generation and propagation of ULF/VLF signals generated as the result of HF radiation modulation. Despite the numerous attempts of long-range detection of such signals, there are a few successful results. The most reliable and important results were obtained by [Barr et al.] more than 20 years ago. They measured the VLF radio waves in Lindau, Germany at the distance of about 2000 km from EISCAT Heater. We present the results of the ULF/VLF registrations at the same distance during heating campaign of February 2012. The measurements were conducted at Mikhnevo Geohysical Observatory located in 80 km to the south of Moscow and at the distance of about 1900 km from Tromsø. For measurements were used a sensitive receivers with crossed air-coil loop antennas in the frequency range from 800 Hz to 30 kHz in the femtotesla amplitude range. We recorded the radial and azimuthal magnetic component of the signals and from their ratio obtained the mode polarization. The radiated heater frequency was modulated by 517, 1017, 2017, 3017, 4017 and 6017 Hz. It was shown the signals with frequency less than 2 kHz propagate in the QTEM mode, and signals at the frequency from 2 to 4 kHz are in the QTE mode. Observed magnetic field strengths and waveguide polarizations are found to be in line with the predictions of simple waveguide models. Qualitative coincidence of the signals polarization character and its dependence on the frequency specifies adequacy of numerical models and reliability of the data received in campaign 2012. Blagoveshchenskaya N. F., M. T. Rietveld et al. Artificial field-aligned irregularities in the high-latitude F region of the ionosphere induced by an X-mode HF heater wave. // Geophys. Res. Lett. - 2011. V. 38, doi: 10.1029/2011GL046724. Barr, R., P. Stubbe, and H. Kopka, 1991, Long-range detection of VLF radiation produced by heating the auroral electrojet. Radio Science, Volume 26, Number 4, Pages 871-879, July-August 1991

  13. An alternative to the plasma emission model: Particle-in-cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts

    SciTech Connect

    Tsiklauri, David

    2011-05-15

    High-resolution (sub-Debye length grid size and 10 000 particle species per cell), 1.5D particle-in-cell, relativistic, fully electromagnetic simulations are used to model electromagnetic wave emission generation in the context of solar type III radio bursts. The model studies generation of electromagnetic waves by a super-thermal, hot beam of electrons injected into a plasma thread that contains uniform longitudinal magnetic field and a parabolic density gradient. In effect, a single magnetic line connecting Sun to Earth is considered, for which five cases are studied. (i) We find that the physical system without a beam is stable and only low amplitude level electromagnetic drift waves (noise) are excited. (ii) The beam injection direction is controlled by setting either longitudinal or oblique electron initial drift speed, i.e., by setting the beam pitch angle (the angle between the beam velocity vector and the direction of background magnetic field). In the case of zero pitch angle, i.e., when v-vector{sub b{center_dot}}E-vector{sub perpendicular}=0, the beam excites only electrostatic, standing waves, oscillating at local plasma frequency, in the beam injection spatial location, and only low level electromagnetic drift wave noise is also generated. (iii) In the case of oblique beam pitch angles, i.e., when v-vector{sub b{center_dot}}E-vector{sub perpendicular}=0, again electrostatic waves with same properties are excited. However, now the beam also generates the electromagnetic waves with the properties commensurate to type III radio bursts. The latter is evidenced by the wavelet analysis of transverse electric field component, which shows that as the beam moves to the regions of lower density and hence lower plasma frequency, frequency of the electromagnetic waves drops accordingly. (iv) When the density gradient is removed, an electron beam with an oblique pitch angle still generates the electromagnetic radiation. However, in the latter case no frequency decrease is seen. (v) Since in most of the presented results, the ratio of electron plasma and cyclotron frequencies is close to unity near the beam injection location, in order to prove that the electromagnetic emission, generated by the non-zero pitch angle beam, oscillates at the plasma frequency, we also consider a case when the magnetic field (and the cyclotron frequency) is ten times smaller. Within the limitations of the model, the study presents the first attempt to produce synthetic (simulated) dynamical spectrum of the type III radio bursts in the fully kinetic plasma model. The latter is based on 1.5D non-zero pitch angle (non-gyrotropic) electron beam that is an alternative to the plasma emission classical mechanism for which two spatial dimensions are needed.

  14. Composite scintillator screen

    DOEpatents

    Zeman, Herbert D. (1687 Peach St., Memphis, TN 38112)

    1994-01-01

    A scintillator screen for an X-ray system includes a substrate of low-Z material and bodies of a high-Z material embedded within the substrate. By preselecting the size of the bodies embedded within the substrate, the spacial separation of the bodies and the thickness of the screen, the sensitivity of the screen to X-rays within a predetermined energy range can be predicted.

  15. Scintillation-induced Intermittency in SETI

    NASA Astrophysics Data System (ADS)

    Cordes, James M.; Lazio, Joseph W.; Sagan, Carl

    1997-10-01

    We use scattering theory, simulations, and empirical constraints on interstellar scintillations to discuss the intermittency of radio signals from extraterrestrial intelligence (ETI). The number of ETI sources in the Galaxy has a direct influence on the expected dynamic range of fluxes in a survey, through inverse square-law effects and, equally importantly, by the number of independent statistical trials made on modulations caused by interstellar scintillations. We demonstrate that scintillations are very likely to allow initial detections of narrowband signals, while making redetections extremely improbable, a result that follows from the skewed, exponential distribution of the modulation. This conclusion holds for relatively distant sources but does not apply to radio SETI toward nearby stars (<~100 pc). Recent SETI has found nonrepeating, narrowband events that are largely unexplained. We consider three models in order to assess these events and to analyze large surveys in general: (model I) radiometer noise fluctuations; (model II) a population of constant Galactic sources that undergo deep fading and amplification due to interstellar scintillation, consistent with ETI transmissions; and (model III) real, transient signals (or hardware errors) of either terrestrial or extraterrestrial origin. We derive likelihood and Bayesian tests of the models for individual events and globally on entire surveys. Applying them to The Planetary Society/Harvard META data, we find that models II and III are both highly preferred to model I, but that models II and III are about equally likely. In the context of model II, the likelihood analysis indicates that candidate events above threshold (~32 ?) are combinations of large amplitude noise fluctuations and scintillation gains, making it highly probable that events seen once will only very rarely be seen again. Ruling out model II in favor of model III is difficult--to do so, many more reobservations (e.g., thousands) are needed than were conducted in META (hundreds) or the reobservation threshold must be much lower than was used in META. We cannot, therefore, rule out the possibility that META events are real, intrinsically steady ETI signals. Our formalism can be used to analyze any SETI program. We estimate the number of reobservations required to rule out model II in favor of model III, taking into account that reobservations made promptly sample the same scintillation gain as in the original detection, while delayed reobservations sample a decorrelated scintillation modulation. The required number is a strong function of the thresholds used in the original survey and in reobservations. We assess optimal methods for applying statistical tests in future SETI programs that use multiple site and multiple beam observations as well as single site observations. We recommend that results be recorded on many more events than have been made to date. In particular, we suggest that surveys use thresholds that are far below the false-alarm threshold that is usually set to yield a small number of noise-induced ``detections'' in a massive survey. Instead, large numbers of events should be recorded in order to (1) demonstrate that background noise conforms to the distribution expected for it; and (2) investigate departures from the expected noise distribution as due to interference or to celestial signals. In this way, celestial signals can be investigated at levels much smaller than the false-alarm threshold. The threshold level for archiving candidate intensities and their corresponding sky positions is best defined in terms of the recording and computational technology that is available at a cost commensurate with other survey costs.

  16. Review of radio science 1984-1986

    NASA Astrophysics Data System (ADS)

    Hyde, G.

    Theoretical, experimental, and applications aspects of radio science are examined in a collection of subject-area reviews. Topics addressed include EM metrology, fields and waves, signals and systems, electronic and optical devices and their applications, and EM noise and interference. Consideration is given to wave propagation and remote sensing, ionospheric radio and wave propagation in plasmas, radio astronomy, and the biological effects of EM waves. An extensive glossary of acronyms is provided.

  17. Observation and Study of Interplanetary Scintillation with the Miyun Telescope

    NASA Astrophysics Data System (ADS)

    Zhang, X. Z.; Wu, J. H.

    We present the preliminary results of observation and study of interplanetry scintillation with the Miyun telescope at Beijing Astronomical Observatory. The properties of the telescope, observing parameters, and data reduction are described in this contribution. The telescope is used daily to trace some radio sources with time scale of several hours a day to measure the velocity variation of solar wind at a position which is relatively fixed to the Sun during each observation. Some observation examples and preliminary analysis are also given.

  18. METHODS OF RADIO-FREQUENCY CURRENT DRIVE

    E-print Network

    -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 attractiveMETHODS OF RADIO-FREQUENCY CURRENT DRIVE N. J. FISCH* Princeton Plasma Physics Laboratory

  19. Lunar components in Lunping scintillations

    SciTech Connect

    Koster, J.R.; Lue, H.Y.; Wu, Hsi-Shu; Huang, Yinn-Nien

    1993-08-01

    The authors report on an anlysis of a 14 year data set of ionospheric scintillation data for 136 MHz signals transmitted from a Japanese satellite. They use a lunar age superposition method to analyze this data, breaking the data into blocks by seasons of the year. They observe a number of different scintillation types in the record, as well as impacts of lunar tides on the time record. They attempt to provide an origin for the different scintillation types.

  20. Simultaneous observations of Jovian quasi-periodic radio emissions by the Galileo and Cassini spacecraft

    E-print Network

    Gurnett, Donald A.

    of many Jovian plasma wave and radio emissions. One of these emissions is Jovian type III radio emissions); 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 6984 Radio Science: Waves in plasma rich in radio and plasma wave emissions. One interesting radio emission component is the quasi

  1. Neutron crosstalk between liquid scintillators

    NASA Astrophysics Data System (ADS)

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-09-01

    A method is proposed to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  2. Pulsar scintillations from corrugated reconnection sheets in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Pen, Ue-Li; Levin, Yuri

    2014-08-01

    We show that surface waves along interstellar current sheets closely aligned with the line of sight lead to pulsar scintillation properties consistent with those observed. This mechanism naturally produces the length-scales and density scales of the interstellar medium (ISM) scattering lenses that are required to explain the magnitude and dynamical spectrum of the scintillations. In this scenario, the parts of warm ionized ISM that are responsible for the scintillations are relatively quiescent, with scintillation and scattering resulting from weak waves propagating along magnetic domain boundary current sheets. These are expected from helicity conservation and have also been observed in numerical simulations. The model statistically predicts the spacing and amplitudes of inverted parabolic arcs seen in Fourier-transformed dynamical spectra of strongly scintillating pulsars with only three parameters. Multifrequency, multi-epoch low-frequency very long baseline interferometry observations can quantitatively test this. If successful, in addition to mapping the ISM, this might allow precise nanoarcsecond pulsar astrometry, distance measurements and emission studies using these 10-au interferometers in the sky.

  3. Excitation of guided ELF-VLF waves through modification of the F{sub 2} ionospheric layer by high-power radio waves

    SciTech Connect

    Markov, G. A.; Belov, A. S.; Komrakov, G. P.; Parrot, M.

    2012-03-15

    The possibility of controlled excitation of ELF-VLF electromagnetic waves through modification of the F{sub 2} ionospheric layer by high-power high-frequency emission is demonstrated in a natural experiment by using the Sura midlatitude heating facility. The excited low-frequency waves can be used to explore the near-Earth space and stimulate the excitation of a magnetospheric maser.

  4. Radio Science in Africa

    NASA Astrophysics Data System (ADS)

    Lefeuvre, Francois; Mc Kinnel, Lee-Anne; Chukwuma, Victor; Amory-Mazaudier, Christine

    2010-05-01

    Radio science activities covered by URSI (International Radio Science Union) are briefly reviewed. They encompass the knowledge and study of all aspects of electromagnetic fields and waves in a wide frequency range running from micro pulsation frequencies (i.e. from ~1 mHz) to Terahertz. The topics include: electromagnetic measurements and standards, electromagnetic theory and applications, radio-communication systems and signal processing, electronics and Photonics, electromagnetic environment and interference, wave propagation and remote sensing, ionospheric radio and propagation, waves in plasmas, radio astronomy, and electromagnetics in biology and medicine. The main radio science activities conducted by the URSI national Committees of South Africa, Egypt and Nigeria, and by African radio scientists groups gathered in GIRGEA (Groupe International de Recherche en Géophysique Europe Afrique) are reviewed. The emphasis is put on the activities developed in the context of the IHY programme and of the SCINDA network for forecasting ionospheric irregularities that adversely impact communication and navigation systems in the low latitude regions.

  5. PRPSIM: A FORTRAN code to calculate properties of radio wave propagation in a structured ionized medium. Volume 2: Theory and models

    NASA Astrophysics Data System (ADS)

    Dodson, R. E.; Krueger, D. J.; Guigliano, F. W.

    1989-12-01

    This report describes the PRPSIM (Properties of Radio Wave Propagation in a Structured Ionized Medium) code, a FORTRAN computer program for use in evaluating electromagnetic propagation effects resulting from detonation of nuclear weapons on satellite communications and radar systems. The code uses nuclear environment data files created by the SCENARIO high altitude, multiburst nuclear phenomenology code. PRPSIM calculates propagation effects due to enhanced mean ionization levels (e.g., absorption, noise, refraction, phase shift, Doppler and time delay variations, etc.). The code is written in ANSI FORTRAN-77 and has been installed and run on VAX, CDC/CYBER, ELXSI/EMBOS, and CRAY-1 computer systems. Volume 1 of the report is a user's guide which describes code installation, input, output, structure, and application. Volume 2 describes the underlying propagation effects theory and computational models.

  6. The 27-day versus 13.5-day variations in the solar Lyman-alpha radiation and the radio wave absorption in the lower ionosphere over Europe

    NASA Technical Reports Server (NTRS)

    Delamorena, B. A.; Lastovicka, Jan; Rapoport, Z. TS.; Alberca, L.

    1989-01-01

    In order to clarify the question of solar periods in absorption, the pattern was studied of the solar Lyman-alpha radiation (the principal ionizing agent of the lower ionosphere) and of the radio wave absorption at five widely spaced places in Europe. When the solar Lyman-alpha flux variability is very well developed, then it dominates in the lower ionospheric variability. The most pronounced Lyman-alpha variation on time scale day-month is the solar rotation variation (about 27 days). When the Lyman-alpha variability is developed rather poorly, as it is typical for periods dominated by the 13.5 day variability, then the lower ionospheric variability appears to be dominated by variations of meteorological origin. The conclusions hold for all five widely spaced placed in Europe.

  7. Experimental study of the propagation conditions of ultrashort radio waves through the sporadic E layer on the Dushanbe-Ashkhabad path

    NASA Astrophysics Data System (ADS)

    Krotov, Iu. P.; Shirmamedov, M.; Babaev, A.; Alimov, O.

    The conditions of radio-wave propagation at an operating frequency of 40.024 MHz on the Dushanbe-Ashkhabad path are investigated. An increase in the threshold value from 10 to 600 s results in a decrease in the sporadic E layer of less than 15 percent. The threshold value for the frequency of 40.024 MHz on the Dushanbe-Ashkhabad path lies within 150 and 220 s. The threshold value of the reflection level from the sporadic-E-signal-intensity layer at a frequency of 40.024 MHz on the Dushanbe-Ashkhabad path lies within 10-20 micro-V. All reflections having a level lower than the signal intensity apply to meteor reflections, and reflections with a level higher than the signal intensity to reflections from the sporadic E layer.

  8. Automatic recognition of type III solar radio bursts in STEREO/WAVES data for onboard real-time and archived data processing

    NASA Astrophysics Data System (ADS)

    Lobzin, V. V.; Cairns, Iver H.; Zaslavsky, A.

    2014-02-01

    Type III radio bursts are produced near the local electron plasma frequency and/or near its harmonic by fast electrons ejected from the solar active regions and moving through the corona and solar wind. These bursts have dynamic spectra with frequency rapidly falling with time. This paper presents two new methods developed to detect type III bursts automatically in the data from High Frequency Receiver (HFR) of the STEREO/WAVES radio instrument onboard the STEREO spacecraft. The first technique is applicable to the low-frequency band (HFR-1: 125 kHz to 1.975 MHz) only. This technique can possibly be implemented in onboard satellite software aimed at preliminary detection of bursts and identification of time intervals with relatively high solar activity. In the second technique the bursts are detected in both the low-frequency band and the high-frequency band (HFR-2: 2.025 MHz to 16.025 MHz), with the computational burden being higher by 1 order of magnitude as compared with that for the first technique. Preliminary tests of the method show that the performance of the first technique is quite high, PdL=72%±3%. The performance of the second technique is considerably higher, PdL+H=81%±1%, while the number of false alarms does not exceed 10% for one daily spectrum.

  9. Remote sensing and modeling of energetic electron precipitation into the lower ionosphere using VLF/LF radio waves and field aligned current data

    NASA Astrophysics Data System (ADS)

    Schmitter, E. D.

    2015-11-01

    A model for the development of electron density height profiles based on space time distributed ionization sources and reaction rates in the lower ionosphere is described. Special attention is payed to the definition of an auroral oval distribution function for energetic electron energy input into the lower ionosphere based on a Maxwellian energy spectrum. The distribution function is controlled by an activity parameter which is defined proportional to radio signal amplitude disturbances of a VLF/LF transmitter. Adjusting the proportionality constant allows to model precipitation caused VLF/LF signal disturbances using radio wave propagation calculations and to scale the distribution function. Field aligned current (FAC) data from the new Swarm satellite mission are used to constrain the spatial extent of the distribution function. As an example electron precipitation bursts during a moderate substorm on the 12 April 2014 (midnight-dawn) are modeled along the subauroral propagation path from the NFR/TFK transmitter (37.5 kHz, Iceland) to a midlatitude site.

  10. Remote sensing and modeling of lightning caused long recovery events within the lower ionosphere using VLF/LF radio wave propagation

    NASA Astrophysics Data System (ADS)

    Schmitter, E. D.

    2014-11-01

    On the 4 November 2012 at 3:04:27 UT a strong lightning in the midst of the North Sea affected the propagation conditions of VLF/LF transmitter radio signals from NRK (Iceland, 37.5 kHz) and GBZ (UK, 19.58 kHz) received at 5246° N 8° E (NW Germany). The amplitude and phase dips show a recovery time of 6-12 min pointing to a LOng Recovery Early VLF (LORE) event. Clear assignment of the causative return stroke in space and time was possible with data from the WWLLN (Worldwide Lightning Location Network). Based on a return stroke current model the electric field is calculated and an excess electron density distribution which decays over time in the lower ionosphere is derived. Ionization, attachment and recombination processes are modeled in detail. Entering the electron density distribution in VLF/LF radio wave propagation calculations using the LWPC (Long Wavelength Propagation Capability) code allows to model the VLF/LF amplitude and phase behavior by adjusting the return stroke current moment. The results endorse and quantify the conception of lower ionosphere EMP heating by strong - but not necessarily extremely strong - return strokes of both polarities.

  11. Prediction of the level of ionospheric scintillation at equatorial latitudes in Brazil using a neural network

    NASA Astrophysics Data System (ADS)

    Lima, G. R. T.; Stephany, S.; Paula, E. R.; Batista, I. S.; Abdu, M. A.

    2015-08-01

    Electron density irregularity structures, often associated with ionospheric plasma bubbles, drive amplitude and phase fluctuations in radio signals that, in turn, create a phenomenon known as ionospheric scintillation. The phenomenon occurs frequently around the magnetic equator where plasma instability mechanisms generate postsunset plasma bubbles and density depletions. A previous correlation study suggested that scintillation at the magnetic equator may provide a forecast of subsequent scintillation at the equatorial ionization anomaly southern peak. In this work, it is proposed to predict the level of scintillation over São Luís (2.52°S, 44.3°W; dip latitude: ~2.5°S) near the magnetic equator with lead time of hours but without specifying the moment at which the scintillation starts or ends. A collection of extended databases relating scintillation to ionospheric variables for São Luís is employed to perform the training of an artificial neural network with a new architecture. Two classes are considered, not strong (null/weak/moderate) and strong scintillation. An innovative scheme preprocesses the data taking into account similarities of the values of the variables for the same class. A formerly proposed resampling heuristic is employed to provide a balanced number of tuples of each class in the training set. Tests were performed showing that the proposed neural network is able to predict the level of scintillation over the station on the evening ahead of the data sample considered between 17:30 and 19:00 LT.

  12. Extruding plastic scintillator at Fermilab

    SciTech Connect

    Anna Pla-Dalmau; Alan D. Bross; Victor V. Rykalin

    2003-10-31

    An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

  13. Scintillation light transport and detection

    NASA Astrophysics Data System (ADS)

    Gabriel, T. A.; Lillie, R. A.

    1987-08-01

    The MORSE neutron gamma-ray transport code has been modified to allow for the transport of scintillation light. This modified code is used to analyze the light collection characteristics of a large liquid scintillator module (18 × 18 × 350 cm 3).

  14. Lithium-loaded liquid scintillators

    DOEpatents

    Dai, Sheng (Knoxville, TN); Kesanli, Banu (Mersin, TR); Neal, John S. (Knoxville, TN)

    2012-05-15

    The invention is directed to a liquid scintillating composition containing (i) one or more non-polar organic solvents; (ii) (lithium-6)-containing nanoparticles having a size of up to 10 nm and surface-capped by hydrophobic molecules; and (iii) one or more fluorophores. The invention is also directed to a liquid scintillator containing the above composition.

  15. Hybrid scintillators for neutron discrimination

    SciTech Connect

    Feng, Patrick L; Cordaro, Joseph G; Anstey, Mitchell R; Morales, Alfredo M

    2015-05-12

    A composition capable of producing a unique scintillation response to neutrons and gamma rays, comprising (i) at least one surfactant; (ii) a polar hydrogen-bonding solvent; and (iii) at least one luminophore. A method including combining at least one surfactant, a polar hydrogen-bonding solvent and at least one luminophore in a scintillation cell under vacuum or an inert atmosphere.

  16. Echo scintillation Index affected by cat-eye target's caliber with Cassegrain lens

    NASA Astrophysics Data System (ADS)

    Shan, Cong-miao; Sun, Hua-yan; Zhao, Yan-zhong; Zheng, Yong-hui

    2015-10-01

    The optical aperture of cat-eye target has the aperture averaging effect to the active detecting laser of active laser detection system, which can be used to identify optical targets. The echo scintillation characteristics of the transmission-type lens target have been studied in previous work. Discussing the differences of the echo scintillation characteristics between the transmission-type lens target and Cassegrain lens target can be helpful to targets classified. In this paper, the echo scintillation characteristics of Cat-eye target's caliber with Cassegrain lens has been discussed . By using the flashing theory of spherical wave in the weak atmospheric turbulence, the annular aperture filter function and the Kolmogorov power spectrum, the analytic expression of the scintillation index of the cat-eye target echo of the horizontal path two-way transmission was given when the light is normal incidence. Then the impact of turbulence inner and outer scale to the echo scintillation index and the analytic expression of the echo scintillation index at the receiving aperture were presented using the modified Hill spectrum and the modified Von Karman spectrum. Echo scintillation index shows the tendency of decreasing with the target aperture increases and different ratios of the inner and outer aperture diameter show the different echo scintillation index curves. This conclusion has a certain significance for target recognition in the active laser detection system that can largely determine the target type by largely determining the scope of the cat-eye target which depending on echo scintillation index.

  17. Historical Radio Astronomy Working Group IAU General Assembly

    E-print Network

    Groppi, Christopher

    the observed radio waves and the stellar atmospheres research. The origin of the radio emission observed be present in the interstellar space to account for a free-free emission of the radio waves. In 1947 UnsöldProgram Historical Radio Astronomy Working Group IAU General Assembly Beijing, China Room 408

  18. Analysis of Radio Wave Propagation for ISM 2.4 GHz Wireless Sensor Networks in Inhomogeneous Vegetation Environments

    PubMed Central

    Azpilicueta, Leire; López-Iturri, Peio; Aguirre, Erik; Mateo, Ignacio; Astrain, José Javier; Villadangos, Jesús; Falcone, Francisco

    2014-01-01

    The use of wireless networks has experienced exponential growth due to the improvements in terms of battery life and low consumption of the devices. However, it is compulsory to conduct previous radio propagation analysis when deploying a wireless sensor network. These studies are necessary to perform an estimation of the range coverage, in order to optimize the distance between devices in an actual network deployment. In this work, the radio channel characterization for ISM 2.4 GHz Wireless Sensor Networks (WSNs) in an inhomogeneous vegetation environment has been analyzed. This analysis allows designing environment monitoring tools based on ZigBee and WiFi where WSN and smartphones cooperate, providing rich and customized monitoring information to users in a friendly manner. The impact of topology as well as morphology of the environment is assessed by means of an in-house developed 3D Ray Launching code, to emulate the realistic operation in the framework of the scenario. Experimental results gathered from a measurement campaign conducted by deploying a ZigBee Wireless Sensor Network, are analyzed and compared with simulations in this paper. The scenario where this network is intended to operate is a combination of buildings and diverse vegetation species. To gain insight in the effects of radio propagation, a simplified vegetation model has been developed, considering the material parameters and simplified geometry embedded in the simulation scenario. An initial location-based application has been implemented in a real scenario, to test the functionality within a context aware scenario. The use of deterministic tools can aid to know the impact of the topological influence in the deployment of the optimal Wireless Sensor Network in terms of capacity, coverage and energy consumption, making the use of these systems attractive for multiple applications in inhomogeneous vegetation environments. PMID:25513820

  19. Analysis of radio wave propagation for ISM 2.4 GHz Wireless Sensor Networks in inhomogeneous vegetation environments.

    PubMed

    Azpilicueta, Leire; López-Iturri, Peio; Aguirre, Erik; Mateo, Ignacio; Astrain, José Javier; Villadangos, Jesús; Falcone, Francisco

    2014-01-01

    The use of wireless networks has experienced exponential growth due to the improvements in terms of battery life and low consumption of the devices. However, it is compulsory to conduct previous radio propagation analysis when deploying a wireless sensor network. These studies are necessary to perform an estimation of the range coverage, in order to optimize the distance between devices in an actual network deployment. In this work, the radio channel characterization for ISM 2.4 GHz Wireless Sensor Networks (WSNs) in an inhomogeneous vegetation environment has been analyzed. This analysis allows designing environment monitoring tools based on ZigBee and WiFi where WSN and smartphones cooperate, providing rich and customized monitoring information to users in a friendly manner. The impact of topology as well as morphology of the environment is assessed by means of an in-house developed 3D Ray Launching code, to emulate the realistic operation in the framework of the scenario. Experimental results gathered from a measurement campaign conducted by deploying a ZigBee Wireless Sensor Network, are analyzed and compared with simulations in this paper. The scenario where this network is intended to operate is a combination of buildings and diverse vegetation species. To gain insight in the effects of radio propagation, a simplified vegetation model has been developed, considering the material parameters and simplified geometry embedded in the simulation scenario. An initial location-based application has been implemented in a real scenario, to test the functionality within a context aware scenario. The use of deterministic tools can aid to know the impact of the topological influence in the deployment of the optimal Wireless Sensor Network in terms of capacity, coverage and energy consumption, making the use of these systems attractive for multiple applications in inhomogeneous vegetation environments. PMID:25513820

  20. Solar Wind observations using the Mexican Array Radio Telescope (MEXART)

    NASA Astrophysics Data System (ADS)

    Romero-Hernandez, E.; Gonzalez-Esparza, A.; Villanueva, P.; Aguilar-Rodriguez, E.; Mejia-Ambriz, J. C.; Mexart

    2013-05-01

    The Mexican Array Radiotelescope (MEXART) is an instrument devoted to observations of radio sources to study large-scale structures in the solar wind employing the Interplanetary Scintillation (IPS) technique. We report recent IPS observations, from January to April of 2013, including an analysis of the scintillation index and the estimation of solar wind velocities for a set of radio sources. We track the first ICMEs registered by the MEXART. We are initiating a continuos operation for a complete monitoring of IPS radio sources that will complement solar wind studies based on in-situ observations.

  1. Intensity Scintillation and Astronomical Quantum Observation

    E-print Network

    Jiang Dong

    2009-11-02

    Holography is 3D imaging which can record intensity and phase at the same time. The importance of construct hologram is holographic recording and wavefront reconstruction. It is surprised that holography be discovered in study interstellar scintillation for pulsar provide a coherent light source recently. I think that is speckle hologram and speckle interference(i.e. intensity interference), and use modern technique which include phased array,CCD, digital signal processing and supercomputer can achieve that digital and computer holography from radio to X-ray astronomy. This means we can use it to image the universe and beyond the limited of telescope for cosmos provide much coherent light from pulsar,maser, black hole to 21cm recombination line. It gives a probe to the medium of near the black hole et al. From those coherent light sources in the sky, we can uncover one different universe that through astronomical quantum observation which use intensity interference.

  2. Width of Radio-Loud and Radio-Quiet CMEs

    E-print Network

    G. Michalek; N. Gopalswamy; H. Xie

    2007-10-24

    In the present paper we report on the difference in angular sizes between radio-loud and radio-quiet CMEs. For this purpose we compiled these two samples of events using Wind/WAVES and SOHO/LASCO observations obtained during 1996-2005. It is shown that the radio-loud CMEs are almost two times wider than the radio-quiet CMEs (considering expanding parts of CMEs). Furthermore we show that the radio-quiet CMEs have a narrow expanding bright part with a large extended diffusive structure. These results were obtained by measuring the CME widths in three different ways.

  3. 86 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 47, NO. 1, JANUARY 1999 Diffraction of Radio Waves from Arbitrary

    E-print Network

    Sarabandi, Kamal

    impedance insert in an infinite plane with one-dimensional (1-D) variation. An integral equation by expanding the dipole field in terms of a continuous spectrum of plane waves. Results are then shown for both are with the Radiation Laboratory, Department of Electrical Engineering and Computer Science, University of Michigan, Ann

  4. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H. (Los Alamos, NM); Seagraves, David T. (Los Alamos, NM)

    2003-01-01

    A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

  5. Waves

    E-print Network

    LaCure, Mari Mae

    2010-04-29

    Waves is the supporting document to the Master of Fine Arts thesis exhibition of the same title. Exhibited March 7-12 2010 in the Art and Design Gallery at the University of Kansas, Waves was comprised of a series of mixed media drawings...

  6. Drift scintillation meter

    NASA Astrophysics Data System (ADS)

    1984-03-01

    This is the final report for the subject contract under which The University of Texas at Dallas (UTD) built, tested and delivered an engineering model and three flight versions of the Drift Scintillation Meter (DSM) to the Air Force Geophysics Laboratory for flight on the Air Force DMSP satellites. The report is divided into three sections. Section 1 contains the instrument description and theory of operation. Section 2 contains a description of planned spacecraft-level instrument testing, stimulation requirements and instrument handling and safety. Section 3 contains an instrument interconnection diagram and a list of the schematics, drawings, parts lists and wiring lists that describe the as-built configuration of the instrument. This documentation is available in the R&D Equipment Information Reports that were submitted to AFGL after each instrument delivery.

  7. Scintillator materials containing lanthanum fluorides

    DOEpatents

    Moses, W.W.

    1991-05-14

    An improved radiation detector containing a crystalline mixture of LaF[sub 3] and CeF[sub 3] as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF[sub 3] and the remainder CeF[sub 3] have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography. 2 figures.

  8. Scintillator materials containing lanthanum fluorides

    DOEpatents

    Moses, William W. (Berkeley, CA)

    1991-01-01

    An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

  9. Properties of scintillator solutes

    SciTech Connect

    Fluornoy, J.M.

    1998-06-01

    This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, {lambda}{sub avg}, at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, {lambda}{sub max}, and emission {lambda}{sub avg} values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs.

  10. Plasma instabilities in the high- and low-latitude E region induced by high-power radio waves. Interim report

    SciTech Connect

    Chaturvedi, P.K.; Ossakow, S.L.

    1990-09-14

    The effect of a high frequency (HF) powerful pump wave on high and low latitude E-region low frequency plasma instabilities is theoretically considered. The growth rates and threshold criteria are calculated for the electrojet associated (Farley-Buneman, gradient-drift) and higher altitude high latitude parallel-current associated (ion-acoustic, ion cyclotron, current convective) instabilities. The results are discussed in the context of present ionospheric modification (heating) experiments, for the high and low latitude ionosphere.

  11. A multi-instrument case study of high-latitude ionospheric GNSS scintillation due to drifting plasma irregularities

    NASA Astrophysics Data System (ADS)

    van der Meeren, C.; Oksavik, K.; Moen, J. I.; Romano, V.

    2013-12-01

    For this study, GPS receiver scintillation and Total Electron Content (TEC) data from high-latitude locations on Svalbard have been combined with several other data sets, including the EISCAT Svalbard Radar (ESR) and allsky cameras, to perform a multi-instrument case study of high-latitude GPS ionospheric scintillations in relation to drifting plasma irregularities at night over Svalbard on 31 October 2011. Scintillations are rapid amplitude and phase fluctuations of electromagnetic signals. GNSS-based systems may be disturbed by ionospheric plasma irregularities and structures such as plasma patches (areas of enhanced electron density in the polar cap) and plasma gradients. When the GNSS radio signals propagate through such areas, in particular gradients, the signals experience scintillations that at best increases positioning errors and at worst may break the receiver's signal lock, potentially resulting in the GNSS receiver losing track of its position. Due to the importance of many GNSS applications, it is desirable to study the scintillation environment to understand the limitations of the GNSS systems. We find scintillation mainly localised to plasma gradients, with predominantly phase scintillation at the leading edge of patches and both phase and amplitude scintillation at the trailing edge. A single edge may also contain different scintillation types at different locations.

  12. Ionospheric irregularities during a substorm event: Observations of ULF pulsations and GPS scintillations

    NASA Astrophysics Data System (ADS)

    Kim, H.; Clauer, C. R.; Deshpande, K.; Lessard, M. R.; Weatherwax, A. T.; Bust, G. S.; Crowley, G.; Humphreys, T. E.

    2014-07-01

    Plasma instability in the ionosphere is often observed as disturbances and distortions of the amplitude and phase of the radio signals, which are known as ionospheric scintillations. High-latitude ionospheric plasma, closely connected to the solar wind and magnetospheric dynamics, produces very dynamic and short-lived Global Positioning System (GPS) scintillations, making it challenging to characterize them. It is observed that scintillations in the high-latitude ionosphere occur frequently during geomagnetic storms and substorms. In addition, it is well known that Ultra Low Frequency (ULF) pulsations (Pi2 and Pi1B) are closely associated with substorm activity. This study reports simultaneous observations of Pi2 and Pi1B pulsations and GPS phase scintillations during a substorm using a newly designed Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) installed at the South Pole. The magnetic field and GPS data from the instruments appear to be associated in terms of their temporal and spectral features. Moreover, the scintillation events were observed near the auroral latitudes where Pi1B pulsations are commonly detected. The temporal, spectral and spatial association between the scintillation and geomagnetic pulsation events suggests that the magnetic field perturbations and enhanced electric fields caused by substorm currents could contribute to the creation of plasma instability in the high-latitude ionosphere, leading to GPS scintillations.

  13. Scintillator fiber optic long counter

    DOEpatents

    McCollum, T.; Spector, G.B.

    1994-03-29

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected is described. 11 figures.

  14. Scintillator fiber optic long counter

    DOEpatents

    McCollum, Tom (Sterling, VA); Spector, Garry B. (Fairfax, VA)

    1994-01-01

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected.

  15. Radio Journalism.

    ERIC Educational Resources Information Center

    Bittner, John R.; Bittner, Denise A.

    This book, a how-to-do-it guide for the novice and the professional alike, deals with several aspects of radio journalism: producing documentaries, preparing and announcing radio news, ethics and responsibility, regulation of radio journalism, and careers. It traces the history and growth of radio news, shows its impact on the public, and…

  16. Modeling solar wind with boundary conditions from interplanetary scintillations

    NASA Astrophysics Data System (ADS)

    Manoharan, P.; Kim, T.; Pogorelov, N. V.; Arge, C. N.; Manoharan, P. K.

    2015-09-01

    Interplanetary scintillations make it possible to create three-dimensional, time- dependent distributions of the solar wind velocity. Combined with the magnetic field observations in the solar photosphere, they help perform solar wind simulations in a genuinely time-dependent way. Interplanetary scintillation measurements from the Ooty Radio Astronomical Observatory in India provide directions to multiple stars and may assure better resolution of transient processes in the solar wind. In this paper, we present velocity distributions derived from Ooty observations and compare them with those obtained with the Wang-Sheeley-Arge (WSA) model. We also present our simulations of the solar wind flow from 0.1 AU to 1 AU with the boundary conditions based on both Ooty and WSA data.

  17. Gravitational waves and red shifts - A space experiment for testing relativistic gravity using multiple time-correlated radio signals

    NASA Technical Reports Server (NTRS)

    Smarr, L. L.; Vessot, R. F. C.; Lundquist, C. A.; Decher, R.; Piran, T.

    1983-01-01

    A two-step satellite mission for improving the accuracy of gravitational wave detection and for observing actual gravity waveforms is proposed. The spacecraft would carry both a highly stable hydrogen maser, which would control a transmitter sending signals to earth, and a Doppler transponder operating in the two-way mode. The use of simultaneous one- and two-way Doppler transmissions offers four time records of frequency pulsations, which can reveal gravitational radiation at 1-10 MHz with an amplitude accuracy of a factor of six. The first mission phase would consist of a Shuttle launch into a highly eccentric orbit to obtain measurements of the gravitational redshift using gravitational potentials of different earth regions to establish that gravity is describable by a metric theory. Then, after a boost into a heliocentric orbit at 6 AU, the earth-satellite system could detect gravitational waves in the solar system, as well as bursts emitted by the collisions of supermassive black holes.

  18. On the antenna calibration of space radio instruments using the galactic background: General formulas

    E-print Network

    California at Berkeley, University of

    and application to STEREO/WAVES, Radio Sci., 46, RS2008, doi:10.1029/2010RS004464. 1. Introduction [2] Radio apply these rela- tions to the antenna calibration of the STEREO/WAVES (S/WAVES) radio instrumentOn the antenna calibration of space radio instruments using the galactic background: General

  19. Extruded plastic scintillator including inorganic powders

    DOEpatents

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-06-27

    A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

  20. Guided radio-wave propagation in the equatorial ionosphere according to the topside sounding onboard Interkosmos-19

    NASA Astrophysics Data System (ADS)

    Karpachev, A. T.; Zhbankov, G. A.; Kuleshova, V. P.; Telegin, V. A.

    2014-12-01

    In addition to normal vertical-incident ionogram traces, strongly remote (up to 2000 km) traces of HF-radio-signal reflections observed on topside-sounder ionograms of the Interkosmos-19 satellite obtained in the equatorial ionosphere are presented. Such traces are connected with waveguides (ducts). These waveguides are field-aligned irregularities of the ionospheric plasma with electron density depletions of a few percent and cross-field dimension of a few to several kilometers. Ray tracing confirms this supposition and allows an estimate of typical waveguide parameters: diameter ?10-15 km and amplitude |?N/N|?10%, where N is the electron density. The waveguide traces usually start at the cutoff frequencies of the main traces. However, sometimes they begin at much lower frequencies which indicates the satellite was transitioning through an equatorial plasma bubble during the recording of the ionogram. The X-mode of ducted echoes is more distinct then the O-mode. Only one ducted trace is usually observed on the Interkosmos-19 ionograms; a second conjugate trace is rarely recorded. The same is true for combination modes which is a combination of an oblique-incidence and guided propagation. Waveguides are observed at all heights of Interkosmos-19 (500-1000 km) inside the equatorial anomaly region (from -40° to +40° Dip). Waveguides are usually associated with other irregularities of various sizes in the equatorial ionosphere, some of which cause additional traces and spread F on the topside-sounding ionograms. Ducted-echo characteristics observed with Interkosmos-19 are different from those observed earlier with the Alouette and ISIS satellites. This difference is discussed. It is shown that the ionospheric plasma irregularities responsible for the waveguides are observed much more often during nighttime than during daytime.

  1. Use of radio-frequency-pulse surface acoustic wave profilometry for passband engineering of acousto-optic tunable filters.

    PubMed

    Rashid, H; Smith, D A; Bao, Z; Chakravarthy, R S; Pathan, M A; Imam, N; Kissa, K; Kallman, J

    1996-03-01

    One can determine the acoustic profile of an acousto-optic tunable filter (AOTF) either by measuring the intensity of a laser diffracted off the surface of an AOTF by the surface acoustic wave (SAW) or by measuring the optical output power of an AOTF as a short burst of rf energy is launched down the device. This rf-burst technique (also called pulse probing) is compared with the established optical diffraction SAW profilometry technique. We demonstrate the usefulness of rf-burst profilometry to measure the acousto-optic coupling as a function of position along an AOTF interaction region. Such a probe can be used to make adjustments to the acousto-optic coupling in real time to achieve passband shape modification in complex AOTF structures. PMID:19865399

  2. High Efficiency Traveling-Wave Tube Power Amplifier for Ka-Band Software Defined Radio on International Space Station-A Platform for Communications Technology Development

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Force, Dale A.; Kacpura, Thomas J.

    2013-01-01

    The design, fabrication and RF performance of the output traveling-wave tube amplifier (TWTA) for a space based Ka-band software defined radio (SDR) is presented. The TWTA, the SDR and the supporting avionics are integrated to forms a testbed, which is currently located on an exterior truss of the International Space Station (ISS). The SDR in the testbed communicates at Ka-band frequencies through a high-gain antenna directed to NASA s Tracking and Data Relay Satellite System (TDRSS), which communicates to the ground station located at White Sands Complex. The application of the testbed is for demonstrating new waveforms and software designed to enhance data delivery from scientific spacecraft and, the waveforms and software can be upgraded and reconfigured from the ground. The construction and the salient features of the Ka-band SDR are discussed. The testbed is currently undergoing on-orbit checkout and commissioning and is expected to operate for 3 to 5 years in space.

  3. 47 CFR 32.2231 - Radio systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., amplification, propagation, reception, modulation, and demodulation of radio waves in free space over which... 47 Telecommunication 2 2014-10-01 2014-10-01 false Radio systems. 32.2231 Section 32.2231... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2231 Radio systems....

  4. Secure Location Verification Using Radio Broadcast

    E-print Network

    Nesterenko, Mikhail

    , exploits the difference between propagation speeds of radio and sound waves to estimate the position1 Secure Location Verification Using Radio Broadcast Adnan Vora and Mikhail Nesterenko Abstract of the prover. In this paper, we propose a solution that leverages the broadcast nature of the radio signal

  5. 47 CFR 32.2231 - Radio systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., amplification, propagation, reception, modulation, and demodulation of radio waves in free space over which... 47 Telecommunication 2 2011-10-01 2011-10-01 false Radio systems. 32.2231 Section 32.2231... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2231 Radio systems....

  6. Philippe Zarka Recherche de transitoires radio associs

    E-print Network

    Meyer-Vernet, Nicole

    LOFAR Search of radio transient counterparts for gravitational waves with LOFAR IVème Ecole de PhysiquePhilippe Zarka LESIA Recherche de transitoires radio associés à des ondes gravitationnelles avec des Astroparticules "Ondes gravitationnelles et Multi-Messagers", OHP, 2013 #12;· RADIO COUNTERPARTS

  7. 47 CFR 32.2231 - Radio systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., amplification, propagation, reception, modulation, and demodulation of radio waves in free space over which... 47 Telecommunication 2 2013-10-01 2013-10-01 false Radio systems. 32.2231 Section 32.2231... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2231 Radio systems....

  8. Packet Radio: An Alternative Way to Connect.

    ERIC Educational Resources Information Center

    Lucas, Larry W.

    1995-01-01

    Explains packet radio as a form of telecomputing in which digital data is transported via radio waves instead of telephone lines or other cabling, and describes how it can be used by students to access the Internet. Highlights include packet bulletin board systems and equipment needed for a packet radio station. (LRW)

  9. Secure Location Verification Using Radio Broadcast

    E-print Network

    Nesterenko, Mikhail

    the difference between propagation speeds of radio and sound waves to estimate the position of the proverSecure Location Verification Using Radio Broadcast Adnan Vora and Mikhail Nesterenko Computer. In this paper, we propose a solution that leverages the broadcast nature of the radio signal emitted

  10. 47 CFR 32.2231 - Radio systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., amplification, propagation, reception, modulation, and demodulation of radio waves in free space over which... 47 Telecommunication 2 2012-10-01 2012-10-01 false Radio systems. 32.2231 Section 32.2231... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2231 Radio systems....

  11. 47 CFR 32.2231 - Radio systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., amplification, propagation, reception, modulation, and demodulation of radio waves in free space over which... 47 Telecommunication 2 2010-10-01 2010-10-01 false Radio systems. 32.2231 Section 32.2231... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2231 Radio systems....

  12. Coronal shock waves observed in images H. S. Hudson

    E-print Network

    California at Berkeley, University of

    . The large-scale coronal shock waves observed from radio type II bursts and from More- ton waves have proven surprisingly difficult to detect in coronal images. I review the evidence for such waves in radio, optical, EUV-scale waves. The discovery of radio type II bursts showed immediately that these waves became shocks

  13. Detection of six rapidly scintillating active galactic nuclei and the diminished variability of J1819+3845

    NASA Astrophysics Data System (ADS)

    Koay, J. Y.; Bignall, H. E.; Macquart, J.-P.; Jauncey, D. L.; Rickett, B. J.; Lovell, J. E. J.

    2011-10-01

    The extreme, intra-hour and >10% rms flux density scintillation observed in AGNs such as PKS 0405-385, J1819+3845 and PKS 1257-326 at cm wavelengths has been attributed to scattering in highly turbulent, nearby regions in the interstellar medium. Such behavior has been found to be rare. We searched for rapid scintillators among 128 flat spectrum AGNs and analyzed their properties to determine the origin of such rapid and large amplitude radio scintillation. The sources were observed at the VLA at 4.9 and 8.4 GHz simultaneously at two hour intervals over 11 days. We detected six rapid scintillators with characteristic time-scales of <2 h, none of which have rms variations >10%. We found strong lines of evidence linking rapid scintillation to the presence of nearby scattering regions, estimated to be <12 pc away for ~200 ?as sources and <250 pc away for ~10 ?as sources. We attribute the scarcity of rapid and large amplitude scintillators to the requirement of additional constraints, including large source compact fractions. J1819+3845 was found to display ~2% rms variations at ~6 h time-scales superposed on longer >11 day variations, suggesting that the highly turbulent cloud responsible for its extreme scintillation has moved away, with its scintillation now caused by a more distant screen ?50 to 150 pc away.

  14. Radiopure Metal-Loaded Liquid Scintillator

    SciTech Connect

    Rosero, Richard; Yeh, Minfang

    2015-03-18

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  15. Unitary scintillation detector and system

    DOEpatents

    McElhaney, S.A.; Chiles, M.M.

    1994-05-31

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

  16. Scintillation at two optical frequencies.

    PubMed

    Hubbard, W B; Reitsema, H J

    1981-09-15

    Stellar scintillation data were obtained on a single night at a variety of zenith distances and azimuths, using a photon-counting photometer recording at 100 Hz simultaneously at wavelengths of 0.475 microm and 0.870 microm. Orientable apertures of 42-cm diam separated by 1 m were used to establish the average upper atmosphere wind direction and velocity. Dispersion in the earth's atmosphere separate the average optical paths at the two wavelengths, permitting a reconstruction of the spatial cross-correlation function for scintillations, independent of assumptions about differential fluid motions. Although there is clear evidence of a complicated velocity field, scintillation power was predominantly produced by levels at pressures of 130 +/- 30 mbar. The data are not grossly inconsistent with layers of isotropic Kolmogorov turbulence, but there is some evidence for deviation from the Kolmogorov spectral index and/or anisotropy. PMID:20333125

  17. Unitary scintillation detector and system

    DOEpatents

    McElhaney, Stephanie A. (Oak Ridge, TN); Chiles, Marion M. (Knoxville, TN)

    1994-01-01

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations.

  18. Fracture-resistant lanthanide scintillators

    DOEpatents

    Doty, F. Patrick (Livermore, CA)

    2011-01-04

    Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

  19. 3D Printing of Scintillating Materials

    E-print Network

    Mishnayot, Y; Cooperstein, I; Magdassi, S; Ron, G

    2014-01-01

    We demonstrate, for the first time, the applicability of 3D printing technique to the manufacture of scintillation detectors. We report of a formulation, usable in stereolithographic printing, that exhibits scintillation efficiency on the order of 30\\% of that of commercial polystyrene based scintillators. We discuss the applicability of these techniques and propose future enhancements that will allow tailoring the printed scintillation detectors to various application.

  20. Nanophosphor composite scintillator with a liquid matrix

    DOEpatents

    McKigney, Edward Allen (Los Alamos, NM); Burrell, Anthony Keiran (Los Alamos, NM); Bennett, Bryan L. (Los Alamos, NM); Cooke, David Wayne (Santa Fe, NM); Ott, Kevin Curtis (Los Alamos, NM); Bacrania, Minesh Kantilal (Los Alamos, NM); Del Sesto, Rico Emilio (Los Alamos, NM); Gilbertson, Robert David (Los Alamos, NM); Muenchausen, Ross Edward (Los Alamos, NM); McCleskey, Thomas Mark (Los Alamos, NM)

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  1. 3D Printing of Scintillating Materials

    E-print Network

    Y. Mishnayot; M. Layani; I. Cooperstein; S. Magdassi; G. Ron

    2014-06-15

    We demonstrate, for the first time, the applicability of 3D printing technique to the manufacture of scintillation detectors. We report of a formulation, usable in stereolithographic printing, that exhibits scintillation efficiency on the order of 30\\% of that of commercial polystyrene based scintillators. We discuss the applicability of these techniques and propose future enhancements that will allow tailoring the printed scintillation detectors to various application.

  2. Hygroscopicity Evaluation of Halide Scintillators

    SciTech Connect

    Zhuravleva, M; Stand, L; Wei, H; Hobbs, C. L.; Boatner, Lynn A; Ramey, Joanne Oxendine; Burger, Arnold; Rowe, E; Bhattacharya, P.; Tupitsyn, E; Melcher, Charles L

    2014-01-01

    A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

  3. Scintillator Cosmic Ray Super Telescope

    NASA Astrophysics Data System (ADS)

    González, L. X.; Valdés-Galicia, J. F.; Matsubara, Y.; Nagai, Y.; Itow, Y.; Sako, T.; López, D.; Mitsuka, G.; Munakata, K.; Kato, C.; Yasue, S.; Kosai, M.; Tsurusashi, M.; Nakamo, Y.; Shibata, S.; Takamaru, H.; Kojima, H.; Tsuchiya, H.; Watanabe, K.; Koi, T.; Fragoso, E.; Hurtado, A.; Musalem, O.

    2013-04-01

    The Scintillator Cosmic Ray Super Telescope (SciCRST) is a new experiment to detect solar neutrons, and also it is expected to work as a muon and cosmic ray detector. The SciCRST consist of 14,848 plastic scintillator bars, and it will be installed at the top of Sierra Negra volcano, Mexico, 4580 m.a.s.l. We use a prototype, called as miniSciBar, to test the hardware and software of the final experiment. In this paper, we present the status and details of the experiment, and results of the prototype.

  4. Composite scintillators for detection of ionizing radiation

    DOEpatents

    Dai, Sheng (Knoxville, TN) [Knoxville, TN; Stephan, Andrew Curtis (Knoxville, TN) [Knoxville, TN; Brown, Suree S. (Knoxville, TN) [Knoxville, TN; Wallace, Steven A. (Knoxville, TN) [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  5. Photonic crystal scintillators and methods of manufacture

    SciTech Connect

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  6. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  7. The Symbiosis of Cognitive Radio and Wireless Mesh Networks

    E-print Network

    Boutaba, Raouf

    a transmitter to encode information and generate radio waves. These electromagnetic waves occurring at lowChapter 18 The Symbiosis of Cognitive Radio and Wireless Mesh Networks Brent Ishibashi and Raouf, the dual usage of wireless communication makes them very resource dependent. Proposed cognitive radio (CR

  8. First calculation of phase and coherence of longitudinally separated L-band equatorial ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Shume, E. B.; Mannucci, A. J.

    2013-07-01

    We present the first calculation of phase and coherence of cross-wavelet transform applied to longitudinally separated L-band equatorial ionospheric scintillation observations received from Geostationary Earth Orbit (GEO) satellites. The phase and coherence analysis were employed on two pairs of observations: (1) São Luís and Rio Branco and (2) Alta Floresta and Huancayo. For these case studies, in statistically significant and high-coherence regions, scintillation observations over São Luís (Alta Floresta) lead that of Rio Branco (Huancayo) by ˜2 to 3 h with a 95%frequency. If L-band scintillation happens over São Luís (Alta Floresta), there is a 95%likelihood that scintillation would happen to the west over Rio Branco (Huancayo) after ˜2 to 3 h, suggesting that a forecast can be made ahead of scintillation occurrences. The phase and coherence relationships between the longitudinally separated scintillation-producing regions can be connected to the large-scale wave structures which are reported to be related to the generation of equatorial spread F and scintillation.

  9. Radio Days.

    ERIC Educational Resources Information Center

    Sanderson, Neil

    1998-01-01

    Thousands of today's high school students run FM radio stations at school, carrying on a tradition that began 50 years ago. Radio helps students learn to work with others and develop a strong sense of responsibility. A sidebar gives advice on starting a high school radio station. (MLF)

  10. Synthesis of plastic scintillation microspheres: Evaluation of scintillators

    NASA Astrophysics Data System (ADS)

    Santiago, L. M.; Bagán, H.; Tarancón, A.; Garcia, J. F.

    2013-01-01

    The use of plastic scintillation microspheres (PSm) appear to be an alternative to liquid scintillation for the quantification of alpha and beta emitters because it does not generate mixed wastes after the measurement (organic and radioactive). In addition to routine radionuclide determinations, PSm can be used for further applications, e.g. for usage in a continuous monitoring equipment, for measurements of samples with a high salt concentration and for an extractive scintillation support which permits the separation, pre-concentration and measurement of the radionuclides without additional steps of elution and sample preparation. However, only a few manufacturers provide PSm, and the low number of regular suppliers reduces its availability and restricts the compositions and sizes available. In this article, a synthesis method based on the extraction/evaporation methodology has been developed and successfully used for the synthesis of plastic scintillation microspheres. Seven different compositions of plastic scintillation microspheres have been synthesised; PSm1 with polystyrene, PSm2 with 2,5-Diphenyloxazol(PPO), PSm3 with p-terphenyl (pT), PSm4 with PPO and 1,4-bis(5-phenyloxazol-2-yl) (POPOP), PSm5 pT and (1,4-bis [2-methylstyryl] benzene) (Bis-MSB), PSm6 with PPO, POPOP and naphthalene and PSm7 with pT, Bis-MSB and naphthalene. The synthesised plastic scintillation microspheres have been characterised in terms of their morphology, detection capabilities and alpha/beta separation capacity. The microspheres had a median diameter of approximately 130 ?m. Maximum detection efficiency values were obtained for the PSm4 composition as follows 1.18% for 3H, 51.2% for 14C, 180.6% for 90Sr/90Y and 76.7% for 241Am. Values of the SQP(E) parameter were approximately 790 for PSm4 and PSm5. These values show that the synthesised PSm exhibit good scintillation properties and that the spectra are at channel numbers higher than in commercial PSm. Finally, the addition of naphthalene modifies the shape of the pulses produced by alpha and beta particles leading to better alpha/beta separation.

  11. A brief Overview of the GSM Radio Interface Thierry Turletti

    E-print Network

    Turletti, Thierry

    Networking. Contents 1 Introduction 2 2 Radio Transmission Aspects 2 3 From Speech to Radio Waves 4 3A brief Overview of the GSM Radio Interface Thierry Turletti Telemedia Networks and Systems Group to the GSM­900 radio interface. It is not exhaustive and it is restricted to the TraOEc Channel

  12. Exploiting Radio Irregularity in Wireless Networks for Automated People Counting

    E-print Network

    T, suffers from radio irregularity ­ a phenomenon referring to radio waves being selectively absorbedExploiting Radio Irregularity in Wireless Networks for Automated People Counting Wei-Chuan Lin. Radio irregularity is often regarded as a problem in wireless communications but, with the envisioned

  13. Firefighters' Radios

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Public Technology Inc. asked for NASA assistance to devise the original firefighter's radio. Good short-range radio communications are essential during a fire to coordinate hose lines, rescue victims, and otherwise increase efficiency. Useful firefighting tool is lower cost, more rugged short range two-way radio. Inductorless electronic circuit replaced inductances and coils in radio circuits with combination of transistors and other low-cost components. Substitution promises reduced circuit size and cost. Enhanced electrical performance made radio more durable and improved maintainability by incorporating modular construction.

  14. Scintillating fiber ribbon --- tungsten calorimeter

    SciTech Connect

    Bross, A.; Crisler, M.; Kross, B.; Wrbanek, J.

    1989-07-14

    We describe an ultra-high density scintillating fiber and tungsten calorimeter used as an active beam-dump for electrons. Data showing the calorimeter response to electrons with momenta between 50 and 350 GeV/c are presented. 9 figs.

  15. SNO+ Scintillator Purification and Assay

    NASA Astrophysics Data System (ADS)

    Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vázquez-Jáuregui, E.

    2011-04-01

    We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O2, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed "natural" radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  16. Interstellar Scintillation and Intraday Variability

    NASA Astrophysics Data System (ADS)

    Rickett, B. J.

    Sources that are compact enough to show intrinsic variability on times of a day or less (IDV) at cm wavelengths must also show interstellar scintillation (ISS) on similar timescales. However for many IDV sources, the variations could be entirely due to ISS, reducing the implied brightness temperatures to $\\sim 1013$~K or less.

  17. SNO+ Scintillator Purification and Assay

    SciTech Connect

    Ford, R.; Vazquez-Jauregui, E.; Chen, M.; Chkvorets, O.; Hallman, D.

    2011-04-27

    We describe the R and D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O{sub 2}, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed ''natural'' radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  18. Method of making a scintillator waveguide

    DOEpatents

    Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder, Paul L. (Richland, WA)

    2000-01-01

    The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

  19. Extruded plastic scintillator for MINERvA

    SciTech Connect

    Pla-Dalmau, Anna; Bross, Alan D.; Rykalin, Victor V.; Wood, Brian M.; /NICADD, DeKalb

    2005-11-01

    An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here.

  20. Scintillators for positron emission tomography

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.

    1995-09-01

    Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ``ultimate`` scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length ({le} 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times {le} 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so {le}5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ``fully-3D`` cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm.

  1. Energy resolution of scintillation detectors

    NASA Astrophysics Data System (ADS)

    Moszy?ski, M.; Syntfeld-Ka?uch, A.; Swiderski, L.; Grodzicka, M.; Iwanowska, J.; Sibczy?ski, P.; Szcz??niak, T.

    2016-01-01

    According to current knowledge, the non-proportionality of the light yield of scintillators appears to be a fundamental limitation of energy resolution. A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals. The important influence of Landau fluctuations and the scattering of secondary electrons (?-rays) on intrinsic resolution is pointed out here. The study on undoped NaI and CsI at liquid nitrogen temperature with a light readout by avalanche photodiodes strongly suggests that the non-proportionality of many crystals is not their intrinsic property and may be improved by selective co-doping. Finally, several observations that have been collected in the last 15 years on the influence of the slow components of light pulses on energy resolution suggest that more complex processes are taking place in the scintillators. This was observed with CsI(Tl), CsI(Na), ZnSe(Te), and undoped NaI at liquid nitrogen temperature and, finally, for NaI(Tl) at temperatures reduced below 0 °C. A common conclusion of these observations is that the highest energy resolution, and particularly intrinsic resolution measured with the scintillators, characterized by two or more components of the light pulse decay, is obtainable when the spectrometry equipment integrates the whole light of the components. In contrast, the slow components observed in many other crystals degrade the intrinsic resolution. In the limiting case, afterglow could also be considered as a very slow component that spoils the energy resolution. The aim of this work is to summarize all of the above observations by looking for their origin.

  2. Magnetohydrodynamic solitons and radio knots in jets

    NASA Technical Reports Server (NTRS)

    Fiedler, R.

    1986-01-01

    Weakly nonlinear surface waves are examined in the context of the beam model for jetlike radio sources. By introducing a finite scale length, viz. the beam radius, geometrical dispersion can act to balance nonlinear wave growth and thereby produce solitons, localized wave packets of stable waveform. A method for obtaining a soliton equation from the MHD equations is presented and then applied to radio knots in jets.

  3. The Poplar Springs Radiometeor Station http://www.amsmeteors.org/radio/poplar.html[2/22/2014 5:27:46 PM

    E-print Network

    Richardson Jr., James E.

    ), the free electrons in this ionized trail are capable of reflecting radio waves from transmitters below rapidly diffuses into the surrounding air, it quickly looses its ability to reflect radio waves, causing capable of reflecting radio waves for up to several minutes. Meteor radio wave reflections are also called

  4. Tracking of Interplanetary CME/Shocks evolution using Type II radio burst observations

    NASA Astrophysics Data System (ADS)

    Aguilar-Rodriguez, E.; Gonzalez-Esparza, A.; Ontiveros, V.

    2010-12-01

    The aim of this work is to apply a new analysis technique, using Type II radio observations in the kilometric (km) domain obtained by the Thermal Noise Receiver (TNR) of the WIND/WAVES experiment, to infer the speed evolution of interplanetary (IP) CME/shocks. These CME/Shocks propagating in the IP medium can generate km Type II radio emissions that occur at the fundamental and/or harmonic of the plasma frequency, so these radio emissions provide a means of remotely tracking CME/shocks. We combine our results with previously reported speeds from coronagraph white light and interplanetary scintillation observations, and in-situ measurements, to study the temporal speed evolution of these events. The shock speed values obtained by our analysis technique are in a reasonable agreement with the speed measurements inferred by other techniques at different heliocentric distance ranges. The combination of all the speed measurements show a gradual deceleration of the CME/shocks as they propagate to 1 AU.

  5. Study of electromagnetic wave scattering by periodic density irregularities in plasma

    SciTech Connect

    Lyle, R.; Kuo, S.P.; Huang, J.

    1995-12-31

    A quasi-particle approach is used to formulate wave propagation and scattering in a periodically structured plasma. The theory is then applied to study the effect of bottomside sinusoidal (BSS) irregularities on the propagation of beacon satellites signals through the ionosphere. In this approach, the radio wave is treated as a distribution of quasi-particles described by a Wigner distribution function governed by a transport equation. The irregularities providing the collisional effect are modeled as a two dimensional density modulation on a uniform background plasma. The present work generalizes the previous work by including the spectral bandwidth ({Delta}k/k) effect of the spatially periodic irregularities on the transionospheric signal propagation. The collision of quasi-particles with the irregularities modifies the quasi-particle distribution and give rise to the wave scattering phenomenon. The multiple scattering process is generally considered in this deterministic analysis of radio wave scattering off the ionospheric density irregularities. The analysis shows that this two dimensional density grating effectively modulates the intensity of the beacon satellite signals. This spatial modulation of the wave intensity is converted into time modulation due to the drift of the ionospheric irregularities, which then results in the scintillation of the beacon satellite signals.

  6. Interstellar scintillation as a probe of microarcsecond scale structure in quasars

    NASA Astrophysics Data System (ADS)

    Bignall, H. E.; Jauncey, D. L.; Lovell, J. E. J.; Kedziora-Chudczer, L.; Macquart, J.-P.; Tzioumis, A. K.; Rickett, B. J.; Ojha, R.; Carter, S.; Cimó, G.; Ellingsen, S.; McCulloch, P. M.

    Observations over the last two decades have shown that a significant fraction of all flat-spectrum, extragalactic radio sources exhibit flux density variations on timescales of a day or less at frequencies of several GHz. It has been demonstrated that interstellar scintillation (ISS) is the principal cause of such rapid variability. Observations of ISS can be used to probe very compact, microarcsecond-scale structure in quasar inner jets, as well as properties of turbulence in the local Galactic ISM. A few sources show unusually rapid, intra-hour variations, evidently due to scattering in very nearby, localized turbulence. We present recent findings for the rapidly scintillating quasar PKS 1257-326. The large-scale MASIV VLA Survey showed that such sources are extremely rare, implying that for most scintillating sources, longer-term, dedicated monitoring programs are required to extract detailed information on source structures. (astro-ph/0412650)

  7. WAVE-DRIVEN ROTATION IN SUPERSONICALLY ROTATING MIRRORS

    E-print Network

    by radio-frequency waves. The waves produce coupled diffusion in ion kinetic and potential energy. A popula, rotation, radio-frequency waves I. INTRODUCTION Magnetic mirror traps with supersonic rotation have many current through electrodes, the rotation could be produced volumetrically by radio-frequency waves near

  8. The solar wind density spectrum near the Sun: Results from Voyager radio measurements

    SciTech Connect

    Coles, W.A.; Liu, W. ); Harmon, J.K.; Martin, C.L. )

    1991-02-01

    Spacecraft radio propagation data are analyzed to estimate the solar wind density fluctuation power spectrum across five decades of spatial wave number. The data were from radio science observations made during superior conjunctions of the Voyager 1 and Voyager 2 spacecrafts in 1979 and 1980. These data were analyzed to yield the wave structure function, a statistic which is related to, but obtained more readily than, the spectrum itself. Structure functions were obtained from a total of 28 observations spanning the heliocentric distance range 7-22 R{sub S}. Each structure function was a composite of two shorter segments estimated, respectively, from phase scintillation and spectral broadening analyses. The composite structure functions tend to be steep (approximately Kolmogorov) at large scales (10{sup 3}-10{sup 6} km) and nearly always show some flattening at smaller scales (10-100 km). The inflection between the steep and flatter regions is abrupt and occurs at scales of 100-300 km. Most of the structure functions also show some turnover at the very smallest scales. These results are in excellent agreement with the spectral shape model proposed by Coles and Harmon (1989). A few transients were seen in the Voyager data which were characterized by an overall increase in power at large scales and a steeping of the structure function at small scales. These transients were similar in appearance to transients reported earlier from Arecibo spectral broadening observations.

  9. 75th anniversary of the N V Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 25 February 2015)

    NASA Astrophysics Data System (ADS)

    2015-06-01

    A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) celebrating the 75th anniversary of the N V Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation of the RAS (IZMIRAN) was held in the IZMIRAN conference hall on 25 February 2015. The agenda of the session announced on the website http://www.gpad.ac.ru of the RAS Physical Sciences Division contained the following reports: (1) Kuznetsov V D (IZMIRAN, Moscow) "N V Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) yesterday, today, and tomorrow"; (2) Gvishiani A D (Geophysical Center, Moscow) "Studies of the terrestrial magnetic field and the network of Russian magnetic laboratories"; (3) Sokoloff D D (Faculty of Physics, Lomonosov Moscow State University, Moscow) "Magnetic dynamo questions"; (4) Petrukovich A A (Space Research Institute, RAS, Moscow) "Some aspects of magnetosphere-ionosphere relations"; (5) Lukin D S (Moscow Institute of Physics and Technology (State University), Dolgoprudnyi, Moscow region) "Current problems of ionospheric radio wave propagation"; (6) Safargaleev V V (Polar Geophysical Institute, Kola Scientific Center, RAS, Murmansk), Sergienko T I (Swedish Institute of Space Physics (IRF), Sweden), Kozlovskii A E (Sodankyl \\ddot a Geophysical Observatory, Finland), Safargaleev A V (St. Petersburg State University, St. Petersburg), Kotikov A L (St. Petersburg Branch of IZMIRAN, St. Petersburg) "Magnetic and optical measurements and signatures of reconnection in the cusp and vicinity"; (7) Kuznetsov V D (IZMIRAN, Moscow) "Space solar research: achievements and prospects". Papers written on the basis of oral reports 1, 3, 4, 6, and 7 are given below. • N V Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) yesterday, today, tomorrow, V D Kuznetsov Physics-Uspekhi, 2015, Volume 58, Number 6, Pages 590-600 • Problems of magnetic dynamo, D D Sokoloff Physics-Uspekhi, 2015, Volume 58, Number 6, Pages 601-605 • Some aspects of magnetosphere-ionosphere relations, A A Petrukovich, M M Mogilevsky, A A Chernyshov, D R Shklyar Physics-Uspekhi, 2015, Volume 58, Number 6, Pages 606-611 • Magnetic and optical measurements and signatures of reconnection in the cusp and vicinity, V V Safargaleev, T I Sergienko, A V Safargaleev, A L Kotikov Physics-Uspekhi, 2015, Volume 58, Number 6, Pages 612-620 • Space solar research: achievements and prospects, V D Kuznetsov Physics-Uspekhi, 2015, Volume 58, Number 6, Pages 621-629

  10. CONFERENCES AND SYMPOSIA: Seventy years of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Waves Propagation (IZMIRAN) (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 25 November 2009)

    NASA Astrophysics Data System (ADS)

    2010-08-01

    A scientific session of the Physical Sciences Division of the Russian Academy of Sciences dedicated to the 70th anniversary of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN) (Troitsk, Moscow region) was held in the conference hall of IZMIRAN on 25 November 2009. The following reports were put on the session agenda posted on the web site www.gpad.ac.ru of the Physical Sciences Division, RAS: (1) Gurevich A V (Lebedev Physical Institute RAS, Moscow) "The role of cosmic rays and runaway electron breakdown in atmospheric lightning discharges"; (2) Aleksandrov E B (Ioffe Physical Technical Institute, RAS, St. Petersburg) "Advances in quantum magnetometry for geomagnetic research"; (3) Dorman L I (IZMIRAN, Troitsk, Moscow region, CR & SWC, Israel) "Cosmic ray variations and space weather"; (4) Mareev E A (Institute of Applied Physics, RAS, Nizhnii Novgorod) "Global electric circuit research: achievements and prospects"; (5) Tereshchenko E D, Safargaleev V V (Polar Geophysical Institute, Kola Research Center, RAS, Murmansk) "Geophysical research in Spitsbergen Archipelago: status and prospects"; (6) Gulyaev Yu V, Armand N A, Efimov A I, Matyugov S S, Pavelyev A G, Savich N A, Samoznaev L N, Smirnov V V, Yakovlev O I (Kotel'nikov Institute of Radio Engineering and Electronics RAS, Fryazino Branch, Fryazino, Moscow region) "Results of solar wind and planetary ionosphere research using radiophysical methods"; (7) Kunitsyn V E (Lomonosov Moscow State University, Moscow) "Satellite radio probing and the radio tomography of the ionosphere"; (8) Kuznetsov V D (IZMIRAN, Troitsk, Moscow region) "Space Research at the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences." Papers based on reports 2-8 are published below. The main contents of report 1 are reproduced in A V Gurevich's review, "Nonlinear effects in the ionosphere" [Phys. Usp. 50 1091 (2007)] and in the paper by A V Gurevich et al., "Nonlinear phenomena in the ionospheric plasma. Effects of cosmic rays and runaway breakdown on thunderstorm discharges" [Phys. Usp. 52 735 (2009)]. • Advances in quantum magnetometry for geomagnetic research , E B Aleksandrov Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 487-496 • Cosmic ray variations and space weather, L I Dorman Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 496-503 • Global electric circuit research: achievements and prospects, E A Mareev Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 504-511 • Geophysical research in Spitsbergen Archipelago: status and prospects, V V Safargaleev, E D Tereshchenko Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 511-517 • Results of solar wind and planetary ionosphere research using radiophysical methods, N A Armand, Yu V Gulyaev, A L Gavrik, A I Efimov, S S Matyugov, A G Pavelyev, N A Savich, L N Samoznaev, V M Smirnov, O I Yakovlev Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 517-523 • Satellite radio probing and radio tomography of the ionosphere, V E Kunitsyn, E D Tereshchenko, E S Andreeva, I A Nesterov Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 523-528 • Space research at the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences , V D Kuznetsov Physics-Uspekhi, 2010, Volume 53, Number 5, Pages 528-534

  11. Gaussian-beam weak scintillation on ground-to-space paths: compact descriptions and Rytov-method applicability

    NASA Astrophysics Data System (ADS)

    Baker, Gary J.; Benson, Robert S.

    2005-10-01

    Recent papers comparing weak-scintillation data from wave-optics simulations with predictions derived from the Rytov perturbation method for ground-to-space Gaussian beams have revealed a region of inaccuracy in the Rytov-based predictions. The discrepancy region is defined by beam diameter and focus settings that place the target in the beam far field and the turbulence in the transmitter near field. Under such conditions turbulence-induced beam wander dominates the scintillation at the target. We develop a solution to the turbulent propagation physics that is applicable in the discrepancy region, and demonstrate agreement in scintillation behavior with our own wave-optics simulation data and with predictions from a rigorous extended Huygens-Fresnel analysis. A combination of our solution and Rytov-based scintillation theory can be used to yield accurate scintillation predictions throughout the weak-scintillation regime for ground-to-space beams. Separately, we show that Rytov-based scintillation theory best describes the physics of a wander-tracking transmitter (where beam wander has been removed from the propagation physics) at the mean transmitter aim point on the target plane, as opposed to the physics of a stationary transmitter.

  12. Radio science investigations by VeRa onboard the Venus Express spacecraft

    NASA Astrophysics Data System (ADS)

    Häusler, B.; Pätzold, M.; Tyler, G. L.; Simpson, R. A.; Bird, M. K.; Dehant, V.; Barriot, J.-P.; Eidel, W.; Mattei, R.; Remus, S.; Selle, J.; Tellmann, S.; Imamura, T.

    2006-11-01

    The Venus Express Radio Science Experiment (VeRa) uses radio signals at wavelengths of 3.6 and 13 cm ("X"- and "S"-band, respectively) to investigate the Venus surface, neutral atmosphere, ionosphere, and gravity field, as well as the interplanetary medium. An ultrastable oscillator (USO) provides a high quality onboard reference frequency source; instrumentation on Earth is used to record amplitude, phase, propagation time, and polarization of the received signals. Simultaneous, coherent measurements at the two wavelengths allow separation of dispersive media effects from classical Doppler shift. VeRa science objectives include the following: Determination of neutral atmospheric structure from the cloud deck (approximately 40 km altitude) to 100 km altitude from vertical profiles of neutral mass density, temperature, and pressure as a function of local time and season. Within the atmospheric structure, search for, and if detected, study of the vertical structure of localized buoyancy waves, and the presence and properties of planetary waves. Study of the H 2SO 4 vapor absorbing layer in the atmosphere by variations in signal intensity and application of this information to tracing atmospheric motions. Scintillation effects caused by radio wave diffraction within the atmosphere can also provide information on small-scale atmospheric turbulence. Investigation of ionospheric structure from approximately 80 km to the ionopause (<600 km), allowing study of the interaction between solar wind plasma and the Venus atmosphere. Observation of forward-scattered surface echoes obliquely reflected from selected high-elevation targets with anomalous radar properties (such as Maxwell Montes). More generally, such bistatic radar measurements provide information on the roughness and density of the surface material on scales of centimeters to meters. Detection of gravity anomalies, thereby providing insight into the properties of the Venus crust and lithosphere. Measurement of the Doppler shift, propagation time, and frequency fluctuations along the interplanetary ray path, especially during periods of superior conjunction, thus enabling investigation of dynamical processes in the solar corona.

  13. Adaptive triggering for scintillation signals

    NASA Astrophysics Data System (ADS)

    Vesic, J.; Vencelj, M.; Strnisa, K.; Savran, D.

    2015-04-01

    Due to the stochastic nature of the pulse creation in a scintillation detector the output pulses are not all of the same shape but rather 'noised' with statistical fluctuations on the pulse tails, which may induce false triggers. The current state of the art in solving this kind of problems is either introducing a deadtime after each pulse which makes the detector inefficient at higher count rates or raising the trigger threshold above the fluctuactions level, which on the other side, lowers the dynamic range of the detector from the low energy side. In order to meet the ever growing demand for high precision/efficient experiments the solutions to these limitations are highly desirable. We propose a new method, the adaptive triggering for scintillation signals.

  14. Silicon photomultipliers for scintillating trackers

    NASA Astrophysics Data System (ADS)

    Rabaioli, S.; Berra, A.; Bolognini, D.; Bonvicini, V.; Bosisio, L.; Ciano, S.; Iugovaz, D.; Lietti, D.; Penzo, A.; Prest, M.; Rashevskaya, I.; Reia, S.; Stoppani, L.; Vallazza, E.

    2012-12-01

    In recent years, silicon photomultipliers (SiPMs) have been proposed as a new kind of readout device for scintillating detectors in many experiments. A SiPM consists of a matrix of parallel-connected pixels, which are independent photon counters working in Geiger mode with very high gain (?106). This contribution presents the use of an array of eight SiPMs (manufactured by FBK-irst) for the readout of a scintillating bar tracker (a small size prototype of the Electron Muon Ranger detector for the MICE experiment). The performances of the SiPMs in terms of signal to noise ratio, efficiency and time resolution will be compared to the ones of a multi-anode photomultiplier tube (MAPMT) connected to the same bars. Both the SiPMs and the MAPMT are interfaced to a VME system through a 64 channel MAROC ASIC.

  15. The Effect of Interplanetary Scintillation on Epoch of Reionisation Power Spectra

    E-print Network

    Trott, Cathryn M

    2015-01-01

    Interplanetary Scintillation (IPS) induces intensity fluctuations in small angular size astronomical radio sources via the distortive effects of spatially and temporally varying electron density associated with outflows from the Sun. These radio sources are a potential foreground contaminant signal for redshifted HI emission from the Epoch of Reionisation (EoR) because they yield time-dependent flux density variations in bright extragalactic point sources. Contamination from foreground continuum sources complicates efforts to discriminate the cosmological signal from other sources in the sky. In IPS, at large angles from the Sun applicable to EoR observations, weak scattering induces spatially and temporally correlated fluctuations in the measured flux density of sources in the field, potentially affecting the detectability of the EoR signal by inducing non-static variations in the signal strength. In this work, we explore the impact of interplanetary weak scintillation on EoR power spectrum measurements, acc...

  16. Application of the locality principle to radio occultation studies of the Earth's atmosphere and ionosphere

    NASA Astrophysics Data System (ADS)

    Pavelyev, A. G.; Liou, Y. A.; Matyugov, S. S.; Pavelyev, A. A.; Gubenko, V. N.; Zhang, K.; Kuleshov, Y.

    2015-07-01

    A new formulation of the previously introduced principle of locality is presented. The principle can be applied for modernization of the radio occultation (RO) remote sensing of the atmospheres and ionospheres of the Earth and other planets. The principle states that significant contributions to variations of the intensity and phase of the radio waves passing through a layered medium are connected with influence of the vicinities of tangential points where the refractivity gradient is perpendicular to the radio ray trajectory. The RO method assumes spherical symmetry of the investigated medium. In this case, if location of a tangent point relative to the spherical symmetry centre is known, the time derivatives of the RO signal phase and Doppler frequency variations can be recalculated into the refractive attenuation. Several important findings are consequences of the locality principle: (i) if position of the centre of symmetry is known, the total absorption along the ray path can be determined at a single frequency; (ii) in the case of low absorption the height, displacement from the radio ray perigee, and tilt of the inclined ionospheric (atmospheric) layers can be evaluated; (iii) the contributions of the layered and irregular structures in the RO signal can be separated and parameters of layers and turbulence can be measured at a single frequency using joint analysis of the intensity and phase variations. Specially for the Earth's troposphere, the altitude distributions of the weak total absorption (about of 1-4 db) of the radio waves at GPS frequencies corresponding to possible influence of the oxygen, water vapour, and hydrometeors can be measured with accuracy of about 0.1 db at a single frequency. In accordance with the locality principle, a new index of ionospheric activity is introduced. This index is measured from the phase variations of radio waves passing through the ionosphere. Its high correlation with the S4 scintillation index is established. This correlation indicates the significant influence of locally spherical symmetric ionospheric layers on variations of the phase and intensity of the RO signal passing through transionospheric communication links. Obtained results expand applicable domain of the RO method as a powerful remote sensing technique for geophysical and meteorological research.

  17. Application of locality principle to radio occultation studies of the Earth's atmosphere and ionosphere

    NASA Astrophysics Data System (ADS)

    Pavelyev, A. G.; Liou, Y. A.; Matyugov, S. S.; Pavelyev, A. A.; Gubenko, V. N.; Zhang, K.; Kuleshov, Y.

    2015-01-01

    A new formulation of previously introduced principle of locality is presented. The principle can be applied for modernization of the radio occultation (RO) remote sensing of the atmospheres and ionospheres of the Earth and planets. The principle states that significant contributions to variations of the amplitude and phase of the radio waves passing through a layered medium are connected with influence of the vicinities of tangential points where the refractivity gradient is perpendicular to the radio ray trajectory. The RO method assumes spherical symmetry of the investigated medium. In this case if location of a tangent point relative to the spherical symmetry center is known, the derivatives on time of the RO signal phase and Doppler frequency variations can be recalculated into the refractive attenuation. Several important findings are consequences of the locality principle: (i) if position of the center of symmetry is known, the total absorption along the ray path can be determined at a single frequency, (ii) in the case of low absorption the height, displacement from the radio ray perigee, and tilt of the inclined ionospheric (atmospheric) layers can be evaluated, (iii) the contributions of the layered and irregular structures in the RO signal can be separated and parameters of layers and turbulence can be measured at a single frequency using joint analysis of the amplitude and phase variations. Specially for the Earth's troposphere, the altitude distributions of the weak total absorption (about of 1-4 db) of the radio waves at GPS frequencies corresponding to possible influence of the oxygen and water vapor can be measured with accuracy of about 0.1 db at a single frequency. According with the locality principle, a new index of ionospheric activity is introduced. This index is measured from the phase variations of radio waves passing through the ionosphere. Its high correlation with S4 scintillation index is established. This correlation indicates the significant influence of locally spherical symmetric ionospheric layers on variations of the phase and amplitude of the RO signal passing through transionospheric communication links. Obtained results expand the applicable domain of the RO method as a powerful remote sensing technique for geophysical and meteorological research.

  18. Laue Diffraction Using Scintillator Detectors

    NASA Astrophysics Data System (ADS)

    Iles, Gail N.; Peetermans, Steven; Schorr, Susan; Lehmann, Eberhard

    The Fast Acquisition Laue Camera for Neutrons (FALCON) is a thermal neutron Laue diffractometer at HZB in Berlin. The instrument comprises two scintillator plate detectors coupled to four iCCD cameras each. One detector is placed in the backscattering position, enabling neutrons to pass through the centre of the detector box. The second detector is free to be placed either in the direct transmission position, or rotated to positions around the sample. The image-intensified CCDs, supplied by Photonic Science Ltd as components of the detector units, are capable of obtaining 20-bit digitization Laue images in under ten seconds. Whilst our instrument will be used as a diffractometer primarily for crystal structure determination, the configuration of the detectors is similar to ICON at PSI in Switzerland, especially in their 'double detector set-up'. In 2015 FALCON enters the commissioning phase whereby one of our activities will be to calibrate the detector units using CONRAD, the cold neutron imaging instrument of HZB. CONRAD will be used to characterise those factors which affect the total efficiency of the detectors i.e. cameras, lenses, CCD chips and the scintillators themselves e.g. homogeneity of the scintillator plate thickness.

  19. The gas scintillation proportional counter

    NASA Astrophysics Data System (ADS)

    Sims, M. R.; Peacock, A.; Taylor, B. G.

    1984-03-01

    The gas scintillation proportional counter has seen rapid development in recent years as a broad-band spectrometer for X-ray astronomy. It may be used in the conjunction with grazing incidence optics or coded aperture masks to produce spectral images of the X-ray sky. Its performance characteristics such as spatial resolution, energy resolution and background rejection efficiency will be described. Reference will be made in large part to work conducted over the last few years at SSD/ESTEC and to work undertaken by the Columbia and Los Alamos groups and at MSSL. The gas scintillator may be coupled to a variety of readout systems including an array of photomultipliers, a microchannel plate or a photoionisation detector. Their relative merits will be reviewed. At high pressures (˜ 3-5 atm) the imaging gas scintillator can be used in nuclear medicine, where its spatial resolution and energy resolution can provide higher resolution images with better contrast than the standard gamma camera.

  20. In Situ Observation of Type II Solar Radio Burst Source Region: a New Generation Mechanism

    E-print Network

    mechanisms: non-thermal -- shock waves -- Sun: radio radiation 1. Introduction Electromagnetic waves can by Cluster spacecraft (Escoubet et al. 1997). We observe intense radio waves above the local plasma frequencyIn Situ Observation of Type II Solar Radio Burst Source Region: a New Generation Mechanism M. V

  1. Secondary scintillation yield in pure xenon

    NASA Astrophysics Data System (ADS)

    Monteiro, C. M. B.; Fernandes, L. M. P.; Lopes, J. A. M.; Coelho, L. C. C.; Veloso, J. F. C. A.; dos Santos, J. M. F.; Giboni, K.; Aprile, E.

    2007-05-01

    The xenon secondary scintillation yield was studied as a function of the electric field in the scintillation region, in a gas proportional scintillation counter operated at room temperature. A large area avalanche photodiode was used for the readout of the VUV secondary scintillation produced in the gas, together with the 5.9 keV x-rays directly absorbed in the photodiode. The latter was used as a reference for the determination of the number of charge carriers produced by the scintillation pulse and, thus, the number of VUV photons impinging the photodiode. A value of 140 photons/kV was obtained for the scintillation amplification parameter. The attained results are in good agreement with those predicted, for room temperature, by Monte Carlo simulation and Boltzmann calculations, as well as with those obtained for saturated xenon vapour, at cryogenic temperatures, and are about a factor of two higher than former results measured at room temperature.

  2. Echo scintillation index affected by cat-eye target's caliber in FSO communication

    NASA Astrophysics Data System (ADS)

    Shan, Cong-miao; Sun, Hua-yan; Zhang, Lai-xian

    2013-08-01

    Cat-eye effect has been widely used in active laser detection, optical target identification and free space optical (FSO) communication, but atmospheric turbulence makes laser beam fluctuate, which limits the use of cat-eye effect. The optical aperture has the aperture averaging effect to the detecting laser, which can be used to identify optical targets. Using the flashing theory of spherical wave in the weak atmospheric turbulence, the circular aperture filter function and the Kolmogorov power spectrum, the analytic expression of the echo scintillation index of the cat-eye target of the horizontal path two-way transmission was given in which the cat-eye target were equivalent to a combination of two circular apertures and the detector of cat-eye target was equivalent to a reflecting plane with the reflectivity ? when the light is normal incidence. Then the impact of turbulence inner and outer scales to the echo scintillation index and the analytic expression of the echo scintillation index at the receiving aperture were presented using the modified Hill spectrum and the modified Von Karman spectrum. The simulation results show that scintillation index of considering the inner scale is larger compared with that of without considering the inner and outer scales and considering the inner and outer scales. Echo scintillation index shows the tendency of decreasing with the target aperture increases. The echo scintillation index increases with the transmission distance increasing.

  3. Kinematics of ICMEs/Shocks: Blast Wave Reconstruction Using Type-II Emissions

    NASA Astrophysics Data System (ADS)

    Corona-Romero, P.; Gonzalez-Esparza, J. A.; Aguilar-Rodriguez, E.; De-la-Luz, V.; Mejia-Ambriz, J. C.

    2015-09-01

    We present a physical methodology for reconstructing the trajectory of interplanetary shocks using Type-II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this blast-wave reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with Type-II emissions. The technique deduces a shock trajectory that reproduces the Type-II frequency drifts and calculates shock onset speed, shock travel time, and shock speed at 1 AU. The BWR results agreed well with the Type-II spectra, with data from coronagraph images, in-situ measurements, and interplanetary scintillation observations. Perturbations in the Type-II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing Type-II emissions in real-time and to predict the shock arrival time and shock speed at 1 AU.

  4. BL LAC OBJECT PKS B1144-379: AN EXTREME SCINTILLATOR

    SciTech Connect

    Turner, R. J.; Ellingsen, S. P.; Shabala, S. S.; Blanchard, J.; Lovell, J. E. J.; McCallum, J. N.; Cimo, G.

    2012-08-01

    Rapid variability in the radio flux density of the BL Lac object PKS B1144-379 has been observed at four frequencies, ranging from 1.5 to 15 GHz, with the Very Large Array and the University of Tasmania's Ceduna antenna. Intrinsic and line-of-sight effects were examined as possible causes of this variability, with interstellar scintillation best explaining the frequency dependence of the variability timescales and modulation indices. This scintillation is consistent with a compact source 20-40 {mu}as or 0.15-0.3 pc in size. The inferred brightness temperature for PKS B1144-379 (assuming that the observed variations are due to scintillation) is 6.2 Multiplication-Sign 10{sup 12} K at 4.9 GHz, with approximately 10% of the total flux in the scintillating component. We show that scintillation surveys aimed at identifying variability timescales of days to weeks are an effective way to identify the active galactic nuclei with the highest brightness temperatures.

  5. Study of equatorial E region irregularities using rare daytime VHF scintillation observations

    NASA Astrophysics Data System (ADS)

    Yadav, V.; Kakad, B.; Pant, T. K.; Bhattacharyya, A.; Prasad, D. S. V. V. D.

    2015-10-01

    Scintillations on VHF radio signal are sparsely observed during daytime due to unavailability of strong electron density irregularities in equatorial E or F region. Type I/II irregularities observed at E region altitudes during the daytime are linked with either two-stream or gradient drift instability. The occurrence of these irregularities in presence of strong blanketing Es (Esb) can produce weak-moderate scintillations on VHF signal during daytime. Such sparse daytime VHF scintillations are used in the present study to retrieve information about E region irregularities, which are generally examined with radar observations. We use spaced receiver scintillation observations on 251 MHz signal transmitted from geostationary satellite UFO2 (71.2°E) and recorded at Tirunelveli (8.5°N, 77.8°E, dip latitude 0.6°N). Ionosonde data from Trivandrum (8.5°N, 76.6°E, dip latitude 0.5°N) during 2003-2005 is used to confirm the association of daytime scintillations with Esb. The daytime scintillations last for 15-45 min during postnoon hours. Their occurrence closely matches the peak occurrence time of Esb. For the first time, spatial scale lengths of E region irregularities are obtained using the technique introduced by Bhattacharyya et al. (2003). The observed spatial scales are validated using theoretical model. The theoretical model manifests 6-19% density fluctuations in the E region to produce weak scintillations (0.15 ?S4? 0.4) on 251 MHz. The study reveals that scale lengths of E region irregularities are smaller on counter equatorial electrojet (CEEJ) days than non-CEEJ days, which could be resulting from lower electron temperatures in E region on CEEJ days.

  6. College Radio.

    ERIC Educational Resources Information Center

    Sauls, Samuel J.

    As with commercial stations, the underlying premise of the college radio station is to serve the community, whether it be the campus community or the community at large, but in unique ways often geared to underserved niches of the population. Much of college radio's charm lies in its unpredictable nature and constant mutations. The stations give…

  7. Radio astronomy

    NASA Technical Reports Server (NTRS)

    Wolken, P. R.; Schaffer, R. D.; Gorenstein, M. V.

    1981-01-01

    The activities of the Deep Space Network in support of Radio Astronomy Operations during April and May 1981 are reported. Work in progres in support of an experiment selected for use of the DSN by the Radio Astronomy Experiment Selection Panel, Twin Quasi-Stellar Object VLBI, is reported.

  8. Radio stars.

    PubMed

    Hjellming, R M; Wade, C M

    1971-09-17

    Up to the present time six classes of radio stars have been established. The signals are almost always very faint and drastically variable. Hence their discovery has owed as much to serendipity as to the highly sophisticated equipment and techniques that have been used. When the variations are regular, as with the pulsars, this characteristic can be exploited very successfully in the search for new objects as well as in the detailed study of those that are already known. The detection of the most erratically variable radio stars, the flare stars and the x-ray stars, is primarily a matter of luck and patience. In the case of the novas, one at least knows where and oughly when to look for radio emission. A very sensitive interferometer is clearly the best instrument to use in the initial detection of a radio star. The fact that weak background sources are frequently present makes it essential to prove that the position of a radio source agrees with that of a star to within a few arc seconds. The potential of radio astronomy for the study of radio stars will not be realized until more powerful instruments than those that are available today can be utilized. So far, we have been able to see only the most luminous of the radio stars. PMID:17836594

  9. Recording of relativistic particles in thin scintillators

    SciTech Connect

    Tolstukhin, I A.; Somov, Alexander S.; Somov, S. V.; Bolozdynya, A. I.

    2014-11-01

    Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering ? quanta in the GlueX experiment.

  10. Waveshifters and Scintillators for Ionizing Radiation Detection

    SciTech Connect

    B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

    2007-12-11

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

  11. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F. (630 Sylvan Pl., Batavia, IL 60510); Sparrow, Robert W. (28 Woodlawn Dr., Sturbridge, MA 01566)

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  12. Timing resolution of the FINUDA scintillation detectors

    NASA Astrophysics Data System (ADS)

    Dalena, B.; D'Erasmo, G.; Di Santo, D.; Fiore, E. M.; Palomba, M.; Simonetti, G.; Andronenkov, A.; Pantaleo, A.; Paticchio, V.; Faso, D.

    2009-05-01

    Experimental characterizations of scintillation detectors timing performance of the internal (TOFINO) and external (TOFONE) scintillator barrels used in FINUDA experiment are presented. The measurements take advantage of detecting synchronous particle pairs produced in the reactions, namely e+e- pairs from Bhabha collisions between the primary beams and K+K- pairs from ?(1020) decay. The method used for synchronizing the multiple detectors constituting the scintillator barrels is also described as being carried out in two steps: a rough one online by the injection of laser light pulses flashing the scintillators all together, and a fine one offline exploiting the timing features of e+e- and K+K- pairs.

  13. Simulations of large acoustic scintillations in the straits of Florida.

    PubMed

    Tang, Xin; Tappert, F D; Creamer, Dennis B

    2006-12-01

    Using a full-wave acoustic model, Monte Carlo numerical studies of intensity fluctuations in a realistic shallow water environment that simulates the Straits of Florida, including internal wave fluctuations and bottom roughness, have been performed. Results show that the sound intensity at distant receivers scintillates dramatically. The acoustic scintillation index SI increases rapidly with propagation range and is significantly greater than unity at ranges beyond about 10 km. This result supports a theoretical prediction by one of the authors. Statistical analyses show that the distribution of intensity of the random wave field saturates to the expected Rayleigh distribution with SI= 1 at short range due to multipath interference effects, and then SI continues to increase to large values. This effect, which is denoted supersaturation, is universal at long ranges in waveguides having lossy boundaries (where there is differential mode attenuation). The intensity distribution approaches a log-normal distribution to an excellent approximation; it may not be a universal distribution and comparison is also made to a K distribution. The long tails of the log-normal distribution cause "acoustic intermittency" in which very high, but rare, intensities occur. PMID:17225385

  14. C/NOFS: a demonstration system to forecast equatorial ionospheric scintillation that adversely affects navigation, communication, and surveillance systems

    NASA Astrophysics Data System (ADS)

    Rich, Frederick J.; de La Beaujardiere, Odile; Retterer, John M.; Basu, Bamandas; Groves, Keith; Jeong, Laila S.; Beach, Theodore; Hunton, Donald; Mellein, Jason; Kachner, Kimberlee

    2004-10-01

    The purpose of the Communication/Navigation Outage Forecasting System (C/NOFS) is to detect and forecast ionospheric irregularities that adversely impact communication, navigation and surveillance systems. The C/NOFS consists of ground sites that monitor the radio link to geosynchronous and GPS spacecraft, a fully-instrumented monitoring satellite scheduled for launch in 2005 and a central data collection facility that creates scintillation warnings in near real-time. The C/NOFS spacecraft will be launched into a low inclination (13°), elliptical (~ 375 x 710 km) orbit. Sensors on the C/NOFS spacecraft measure the ambient ionosphere near the equator and detect density fluctuations which cause scintillation. Ionospheric irregularities often occur after sunset within +/-20° of the magnetic equator. These irregularities can be fairly benign, causing a small amount of radio scintillation and perturbing only UHF/VHF communications, or they can be very severe, causing L-band scintillation that interfere with the functioning of GPS receivers. In these severe cases, the ionospheric irregularities can extend beyond 1000 km altitude. One of the challenges of this project is to go beyond detecting irregularities and to predict scintillation-producing irregularities up to 8 hours into the future and estimating changes in the climatology 24 hours or more into the future.

  15. Scintillation properties of lead sulfate

    SciTech Connect

    Moses, W.W.; Derenzo, S.E. ); Shlichta, P.J. )

    1991-11-01

    We report on the scintillation properties of lead sulfate (PbSO{sub 4}), a scintillator that show promise as a high energy photon detector. It physical properties are well suited for gamma detection, as its has a density of 6.4 gm/cm{sup 3}, a 1/e attenuation length for 511 keV photons of 1.2 cm, is not affected by air or moisture, and is cut and polished easily. In 99.998% pure PbSO{sub 4} crystals at room temperature excited by 511 keV annihilation photons, the fluorescence decay lifetime contains significant fast components having 1.8 ns (5%) and 19 ns (36%) decay times, but with longer components having 95 ns (36%) and 425 ns (23%) decays times. The peak emission wavelength is 335 nm, which is transmitted by borosilicate glass windowed photomultiplier tubes. The total scintillation light output increases with decreasing temperature fro 3,200 photons/MeV at +45{degrees}C to 4, 900 photons/MeV at room temperature (+25{degrees}C) and 68,500 photons/MeV at {minus}145{degrees}C. In an imperfect, 3 mm cube of a naturally occurring mineral form of PbSO{sub 4} (anglesite) at room temperature, a 511 keV photopeak is seen with a total light output of 60% that BGO. There are significant sample to sample variations of the light output among anglesite samples, so the light output of lead sulfate may improve when large synthetic crystals become available. 10 refs.

  16. Simulating Moving Features in Pulsar Scintillation Arcs

    NASA Astrophysics Data System (ADS)

    Myers, J. A.; Rudolph, M. L.; Stinebring, D. R.; Coles, W. A.; Rickett, B. J.

    2005-12-01

    Pulsar scintillation often shows organized and simple structure in a power spectrum analysis. In particular, the power in the secondary spectrum is frequently organized along parabolas that can be identified with thin scattering screens in the interstellar medium. Hill et al. (2005) showed an example in which substructure moved along a parabolic path in accord with the known motion of the pulsar across the sky and the derived distance to the scattering screen. We report results of a simulation in which coherent electromagnetic waves are propagated through a turbulent phase-changing screen causing interference effects at the observer. The inhomogeneities in the screen are assumed to have a Kolmogorov spectrum and are localized in distinct clouds embedded in the screen. We find movement in the secondary spectrum substructure that is consistent with the observations reported by Hill et al. (2005). We comment on the physical implications of the isolated substructure and its persistence in both the simulation and the observations. This work was supported by the National Science Foundation.

  17. Photodetectors for Scintillator Proportionality Measurement

    SciTech Connect

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  18. Need a Classroom Stimulus? Introduce Radio Astronomy

    ERIC Educational Resources Information Center

    Derman, Samuel

    2010-01-01

    Silently, invisibly, ceaselessly, our planet Earth is showered by radio waves from every direction and from every region of space. This radio energy originates in our solar system, throughout the Milky Way galaxy, and far beyond, out to the remotest reaches of the universe. Detecting and unraveling the origins of these invisible signals is what…

  19. Rural Radio in Dahomey: September, 1972.

    ERIC Educational Resources Information Center

    McAnany, Emile G.

    Rural Radio (RR) in Dahomey has a radio network that covers most of the national territory with two transmitters plus 4KW short wave. The program themes are suggested by an advisory group from interested ministries such as Education, Youth and Sport, Agriculture, Health, etc., but the primary objective of the project lies in promoting dialogues…

  20. Aperture averaging of optical scintillations in CO{sub 2} DIAL

    SciTech Connect

    Nelson, D.H.; Petrin, R.R.; Schmitt, M.J.; Whitehead, M.C.; Walters, D.L.

    1997-10-01

    Atmospheric turbulence causes several effects on a propagating laser beam. The authors have previously studied the effects of beam spreading and beam wander, and feel they have a good understanding of their impact on CO{sub 2} DIAL. Another effect is scintillation where atmospheric turbulence causes irradiance fluctuations within the envelope of the beam profile. They believe that scintillation at the target plays an important role in LIDAR return statistics. A Huygens-Fresnel wave optics computer simulation for propagating beams through atmospheric optical turbulence has been previously developed. They modify this simulation to include the effects of reflective speckle and examine its application in comparison with experimental data.