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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. Morphology of auroral zone radio wave scintillation

    SciTech Connect

    Rino, C.L.; Matthews, S.J.

    1980-08-01

    This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation activity followed the general pattern of local magnetic activity. The most prominent feature in the nightime data is a localized amplitude and phase scintillation enhancement at the point where the propagation vector lies within an L shell. A geometrical effect due to a dynamic slab of sheetlike structures in the F region is hypothesized as the source of his enhancement. The data have been sorted by magnetic activity, proximity to local midnight, and season. The general features of the data are in agreement with the accepted morphology of auroral zone scintillation.

  3. 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).

  4. Radio Wave Scintillations and Models of Interstellar Turbulence

    NASA Astrophysics Data System (ADS)

    Spangler, Steven R.

    1998-05-01

    There are a number of well-established observational results from radio scintillations which have implications for the nature of interstellar turbulence. Among such results are evidence for anisotropy and a Kolmogorov spectrum for the density irregularities. It is probable the galactic magnetic field organizes these irregularities so that spatial gradients along the field are much less than those perpendicular to the field. Such a behavior for turbulence is predicted by theories of magnetohydrodynamic turbulence in which the amplitude is small. The turbulence is then described by a theory termed reduced magnetohydrodynamics. A limiting case of reduced magnetohydrodynamics is two dimensional magnetohydrodynamics, in which the direction of the large scale magnetic field z defines the ignorable coordinate. Two dimensional magnetohydrodynamics consists of a pair of coupled nonlinear partial differential equations for the velocity stream function psi and the z component of the magnetic vector potential A_z. A number of observed features of interstellar turbulence can be identified with solutions to the equations of two dimensional magnetohydrodynamics. Examples are the development of Kolmogorov-like spectra for the velocity and magnetic field from a wide class (although not totally general) initial conditions, a natural explanation for the formation of intermittancy in turbulence, and the rapid development of small scale, large spatial wavenumber fluctuations, in contrast to the eddy cascade of hydrodynamic turbulence. The equations of two dimensional magnetohydrodynamics may serve as a simple but tractable model of interstellar plasma turbulence that may complement and be superior to the traditional model of an ensemble of magnetohydrodynamic waves.

  5. Radio scintillations in Venus's atmosphere: application of a theory of gravity wave generation.

    NASA Astrophysics Data System (ADS)

    Leroy, S. S.; Ingersoll, A. P.

    1996-04-01

    Radio scintillations in Pioneer Venus radio occultation data are simulated assuming that the index of refraction fluctuations in Venus's atmosphere responsible for the scintillations are directly caused by gravity wave fluctuations. The gravity waves are created by a global convection layer between 50- and 55-km altitude in Venus's atmosphere and propagate vertically. The authors compare the simulated scintillations with data from Pioneer Venus. These gravity waves can explain the spectral shape and amplitude of the radio scintillations. The shape at high frequencies is controlled by wave breaking, which yields a saturated spectrum. The amplitude is subject to parameters such as the intensity of the convection, the angle between the zonal winds and the beam path, and the zonal wind profile at polar latitudes. To match the observed amplitude of the scintillations, the velocity variations of the energy-bearing eddies in the convection must be at least 2 m s-1. This value is consistent with the Venus balloon results of Sagdeev et al. (1986) and is in the middle of the range considered by Leroy and Ingersoll (1994) in their study of convectively generated gravity waves. The latter study, combined with the lower bound on velocity from the present study, then yields lower bounds on the vertical fluxes of momentum and energy in the Venus atmosphere.

  6. Spacecraft Radio Scintillation and Solar System Exploration

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

    When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of

  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 wave.

    PubMed

    Elkin, V

    1992-01-01

    In developing countries with high rates of poverty and illiteracy, radio is emerging as an excellent medium for delivering information on health issues, family planning, nutrition, and agricultural development. Since radio does not require wired electricity, it can reach remote rural populations. Surveys have found that between 50-75% of poor rural households in developing countries own radios, and the majority listen to educational radio at least once a week. A program that reaches the urban poor outside of Lima, Peru, has been instrumental in controlling the spread of cholera. A Bolivian station broadcasts 8 hours of literacy, health, agricultural, and cultural programming a day to an audience of more than 2 million Aymara Indians. Small village radio stations with a broadcast range of 15 miles can be established for under US$400 and can generally achieve sustainability through local fundraising events such as raffles. In many cases, listeners have become broadcasters at their local radio stations. PMID:12286181

  10. 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.

  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. Looking for radio waves with a simple radio wave detector

    NASA Astrophysics Data System (ADS)

    Sugimoto (Stray Cats), Norihiro

    2011-11-01

    I created a simple device that can detect radio waves in a classroom. In physics classes I tell students that we live in a sea of radio waves. They come from TV, radio, and cell phone signals as well as other sources. Students don't realize this because those electromagnetic waves are invisible. So, I wondered if I could come up with a way to detect the waves and help students to understand them better. Electromagnetic wave meters, which measure intensity of radio waves quantitatively, are commercially available. However, to students most of these are black boxes, and at the introductory level it is more effective to detect radio waves in a simpler way. This paper describes my device and how I have used it in my classes.

  13. Characterizing Daytime GHZ Scintillation at Equatorial Regions Using Gnss Radio Occultation Measurements

    NASA Astrophysics Data System (ADS)

    Seif, A.; Zhang, K.; Tsunoda, R. T.; Abdullah, M.; Carter, B. A.; Norman, R.; Wu, S.

    2015-12-01

    Ionospheric scintillation of radio waves can behave differently at different locations with a strong diurnal dependence; particularly in the equatorial regions. Ionospheric scintillations at gigahertz (GHz) frequencies have been observed during both daytime and nighttime. It is believed that daytime scintillation is associated with blanketing sporadic E (Esb), whereas nighttime scintillation is attributed to F layer irregularities. Scintillation events associated with Esbduring daytime are of our primary interest. Recent studies show that in the ionosphere, electron density profiles from Global Navigation Satellite System (GNSS) Radio Occultation (RO) provide valuable information to help better understand the physics of the ionosphere. In particular, GNSS RO observations of GHz scintillation in the proximity of the E-layer have been interpreted as being caused by sporadic E. In this paper the characteristics of daytime scintillations at 1.5 GHz recorded simultaneously from two stations (i) Universiti Kebangsaan Malaysia (UKM) (2.55°N, 101.461°E; dip latitude 5.78°S), and (ii) Langkawi (6.19°N, 99.51°E; dip latitude 1.90°S) during November and December 2010 are analyzed. The characteristics of daytime GHz scintillation and its relationship with E region irregularities at equatorial regions are investigated. Ground-based scintillation and Total Electron Content (TEC) data recorded by the GSV4004 receivers were utilized in combination with the amplitude scintillation measurements in terms of GPS C/A code SNR fluctuations during a ground-based GPS and space-borne GNSS RO experiment at the two equatorial stations. Scintillation activity was found to be more prominent at UKM. Moreover, strong scintillation with the S4 index exceeding 0.6 has only been observed at UKM, while at Langkawi the scintillation intensity (S4 index) did not exceed 0.3. Signal-to-noise measurements obtained from GNSS RO indicate that daytime scintillations are very likely caused by Esb. Our

  14. 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.

  15. HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations

    SciTech Connect

    Alfred, F.

    1982-01-01

    HF-waves incident on an overdense (HF-frequency < penetration frequency) ionosphere are known to produce large scale electron density irregularities. It is predicted that similar irregularities are formed during underdense HF-modification. The propagation of UHF radio waves originating from radio stars will be affected by such irregularities in the ionosphere. The interest in a scintillation experiment is twofold. One may obtain information on the electron density irregularies and one may learn about the propagation of radio waves through such a perturbed medium. A thin screen (diffractive) theory is derived which allows to draw conclusons on the electron density irregularities from the intensity fluctuations measured on the ground if the phase perturbations are much less than one radian. Since radio stars suitable for scintillation measurements at UHF are very faint an antenna with a large collection area is required. The observations reported in this dissertation were performed with the 300m diameter spherical reflector of the Arecibo Observatory. Successful observations were performed at 430 MHz and at 1400 MHz. Intensity fluctuations at such high frequencies measured with a large antenna suffer severe filtering in the thin phase screen regime. The theory presented in this dissertation includes these filtering effects. Many observations agree with the predictions of that theory. Some observations indicate that refraction effects have to be included to explain the data. HF-induced electron density irregularities were only observed during overdense heating.

  16. Outflow Structure of the Quiet Sun Corona Probed by Spacecraft Radio Scintillations in Strong Scattering

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  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. Scintillation of spacecraft radio signals on the interplanetary plasma

    NASA Astrophysics Data System (ADS)

    Molera Calves, Guifre; Pogrebenko, Sergei; Cimo, Giuseppe; Duev, Dmitry; Bocanegra, Tatiana

    2015-04-01

    Observations of planetary spacecraft radio signals within the solar system give a unique opportunity to study the temporal and spatial behaviour of the signal's phase fluctuations caused by its propagation through the interplanetary plasma and the Earth's ionosphere. The phase scintillation of the telemetry signal of the European Space Agency's (ESA) Venus Express (VEX) and Mars Express (MEX) spacecraft was observed at X-band with a number of radio telescopes of the European VLBI Network (EVN) in the period 2008-15, within the scope of Planetary Radio Interferometry and Doppler Experiment (PRIDE) project. It was found that the phase scintillation spectra follow a Kolmogorov distribution with nearly constant spectral index of -2.42 for a full range of Venus orbital phases, from superior to inferior conjunctions and back. The solar wind plasma dominates the scintillation index and Doppler noise along the orbit from superior conjunction to the greatest elongation. Here, I will present the latest results of these observations, while approaching the inferior conjunction, where the Earth ionosphere starts to dominate, and also at the superior conjunction. Empirical coefficients for both contributions were estimated and compared for VEX and MEX.

  19. Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB 150418

    NASA Astrophysics Data System (ADS)

    Akiyama, Kazunori; Johnson, Michael D.

    2016-06-01

    Keane et al. have recently reported the discovery of a new fast radio burst (FRB), FRB 150418, with a promising radio counterpart at 5.5 and 7.5 GHz—a rapidly decaying source, falling from 200–300 μJy to 100 μJy on timescales of ˜6 days. This transient source may be associated with an elliptical galaxy at redshift z = 0.492, providing the first firm spectroscopic redshift for an FRB and the ability to estimate the density of baryons in the intergalactic medium via the combination of known redshift and radio dispersion of the FRB. An alternative explanation, first suggested by Williams & Berger, is that the identified counterpart may instead be a compact active galactic nucleus (AGN). The putative counterpart’s variation may then instead be extrinsic, caused by refractive scintillation in the ionized interstellar medium of the Milky Way, which would invalidate the association with FRB 150418. We examine this latter explanation in detail and show that the reported observations are consistent with scintillating radio emission from the core of a radio-loud AGN having a brightness temperature T b ≳ 109 K. Using numerical simulations of the expected scattering for the line of sight to FRB 150418, we provide example images and light curves of such an AGN at 5.5 and 7.5 GHz. These results can be compared with continued radio monitoring to conclusively determine the importance of scintillation for the observed radio variability, and they show that scintillation is a critical consideration for continued searches for FRB counterparts at radio wavelengths.

  20. Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB 150418

    NASA Astrophysics Data System (ADS)

    Akiyama, Kazunori; Johnson, Michael D.

    2016-06-01

    Keane et al. have recently reported the discovery of a new fast radio burst (FRB), FRB 150418, with a promising radio counterpart at 5.5 and 7.5 GHz—a rapidly decaying source, falling from 200–300 μJy to 100 μJy on timescales of ∼6 days. This transient source may be associated with an elliptical galaxy at redshift z = 0.492, providing the first firm spectroscopic redshift for an FRB and the ability to estimate the density of baryons in the intergalactic medium via the combination of known redshift and radio dispersion of the FRB. An alternative explanation, first suggested by Williams & Berger, is that the identified counterpart may instead be a compact active galactic nucleus (AGN). The putative counterpart’s variation may then instead be extrinsic, caused by refractive scintillation in the ionized interstellar medium of the Milky Way, which would invalidate the association with FRB 150418. We examine this latter explanation in detail and show that the reported observations are consistent with scintillating radio emission from the core of a radio-loud AGN having a brightness temperature T b ≳ 109 K. Using numerical simulations of the expected scattering for the line of sight to FRB 150418, we provide example images and light curves of such an AGN at 5.5 and 7.5 GHz. These results can be compared with continued radio monitoring to conclusively determine the importance of scintillation for the observed radio variability, and they show that scintillation is a critical consideration for continued searches for FRB counterparts at radio wavelengths.

  1. Application of refractive scintillation theory to radio transmission through the ionosphere and the solar wind, and to reflection from a rough ocean

    NASA Astrophysics Data System (ADS)

    Booker, H. G.

    1981-11-01

    The theory of diffractive scattering by small-scale irregularities is combined with the results of Booker and MajidiAhi (1981) concerning refractive scattering by large-scale irregularities in a phase-changing screen, in a study of three intensity scintillation phenomena: (1) the reflection of radio and optical waves from an ocean surface disturbed by a spectrum of water waves; (2) the scintillation of VHF, UHF and SHF radio waves traversing the ionospheric F-region; and (3) the scintillation of the radio waves mentioned while traversing the solar wind. Spectral diagrams are drawn to show how the outer, inner, Fresnel, focal, lens and peak scales vary with such relevant parameters as electromagnetic wave-frequency for the ocean, RMS fractional fluctuation of ionization density for the ionosphere, and distance of closest approach to the sun for the solar wind.

  2. Characterization of Ionospheric Scintillation Using Simultaneous Formosat-3/COSMIC Radio Occultation Observations and AFRL SCINDA Ground Scintillation Measurements

    NASA Astrophysics Data System (ADS)

    Starks, M. J.; Lin, C. S.; Groves, K. M.; Pedersen, T. R.; Basu, S.; Syndergaard, S.; Rocken, C.

    2007-05-01

    Ionospheric scintillation at low latitudes has been studied using ionospheric radio occultation (RO) measurements by the FORMOSAT-3/COSMIC micro-satellites in conjunction with ground-based data from the Scintillation Network Decision Aid (SCINDA) station at Kwajalein Atoll. The Air Force Research Laboratory has developed the SCINDA network for monitoring low-latitude ionospheric total electron content (TEC) and scintillation associated with equatorial spread F. The network currently consists of sixteen stations distributed around the globe and the data have been used to conduct numerous studies on the characteristics and climatology of equatorial scintillation. The present study focuses on COSMIC RO and SCINDA data during the three COSMIC campaigns in 2006. Radio occultation events are selected by requiring that ionospheric scintillation was detected by the SCINDA VHF scintillation monitor at Kwajalein, and that the occultation ray path intersected the Kwajalein longitude below the satellite altitude, which varied from 500 to 800 km for the six FORMOSAT-3 satellites. In order to exclude tropospheric effects, only GPS signal amplitudes from FORMOSAT-3 with ray path tangent altitudes above 100 km are considered. Locations of ionospheric scintillation are estimated by triangulation using the satellites and the SCINDA ground station. Airglow images at Kwajalein are also used to confirm occurrence of equatorial ionospheric scintillations. For the selected events, large amplitude L1 and L2 scintillations tend to occur at altitudes below 200 km at frequencies around 0.5 Hz. The results are discussed as a potential path toward better specifying the occurrence of equatorial scintillations.

  3. Space velocities of radio pulsars from interstellar scintillations

    SciTech Connect

    Cordes, J.M.

    1986-12-01

    Scintillation observations are used to determine the space velocities of 71 radio pulsars, including most of the 26 objects with proper motions derived from interferometry. The scintillation velocity is dominated by the peculiar transverse velocity of the neutron star and is insensitive to differential galactic rotation. Velocities have a broad distribution function ranging up to about 150 km/s with a tail extending to about 300 km/s. There is no definitive appearance of a bimodal distribution, however. A correlation of velocity with PP(dot) is confirmed to be a general property of the radio pulsar population. It cannot be explained by any observational selection effect and most plausibly is due to a relationship between a neutron star's magnetic moment and the momentum impulse given to it at or near the time of its formation. A small fraction of the objects are discrepant with respect to the velocity-PP(dot) relation. For some objects, this discrepancy may be evidence for a peculiar evolutionary history. 41 references.

  4. Radio wave propagation in pulsar magnetospheres

    NASA Astrophysics Data System (ADS)

    Petrova, S. A.; Lyubarskii, Yu. E.

    Pulsar magnetospheres are known to contain an ultrarelativistic highly magnetized plasma which streams along the open magnetic lines. The radio emission observed from pulsars is believed to originate sufficiently deep in the open field line tube, so that the characteristics of outgoing waves can be influenced by propagation in the magnetospheric plasma. Refraction of radio waves in pulsar magnetospheres appears to be efficient. The effect not only influences the observed pulse width and its frequency dependency. It can alter the apparent spatial structure of pulsar emission region which can be derived from the observations of pulsar interstellar scintillations. Transverse ray separation versus pulse longitude calculated allowing for magnetospheric refraction appears to be in qualitative agreement with that observed. In particular, the nonmonotonic character of the curve can be attributed to nonmonotonic distribution of the plasma number density across the open field line tube which makes the rays emitted at different spatial locations deviate in the opposite directions. Proceeding from the frequency dependence of refraction some predictions are made about the frequency evolution of the apparent spatial structure of pulsar emission region. Magnetospheric refraction can also determine the profile shape giving rise to ray grouping into separate components. It will be demonstrated that the salient features of profile morphology can be explained within the frame of a primordial hollow-cone emission model taking into account refraction of rays in pulsar plasma. Then the frequency evolution of profile structure is naturally interpreted as a consequence of frequency dependence of refraction. As the waves propagate in the magnetospheric plasma their polarization also evolves essentially. In the vicinity of the emission region normal waves are linearly polarized and propagate independently, with the polarization plane following the orientation of the local magnetic field. As

  5. Ionospheric scintillations at Guilin detected by GPS ground-based and radio occultation observations

    NASA Astrophysics Data System (ADS)

    Zou, Yuhua

    2011-03-01

    The occurrence of ionospheric scintillations with S4 ⩾ 0.2 was studied using GPS measurements at Guilin, China (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of the equatorial anomaly. The results are presented for data collected from January 2009 to March 2010. The results show that nighttime amplitude scintillations only took place in February and March of the considered years, while daytime amplitude scintillations occurred in August and December of 2009. Nighttime amplitude scintillations, observed in the south of Guilin, always occurred with phase scintillations, TEC (Total Electron Content) depletions, and ROT (Rate Of change of TEC) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations always took place simultaneously for most of the GPS satellites which appeared over Guilin in different azimuth directions. Ground-based GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio (SNR) measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively. Moreover, strong daytime amplitude scintillations may be associated with the plasma density enhancements in ionospheric E region caused by the Perseid and Geminid meteor shower activities.

  6. UHF Radio Wave Attenuation Factor Database

    NASA Astrophysics Data System (ADS)

    Khomenko, S. I.; Kostina, V. L.; Mytsenko, I. M.; Roenko, A. N.

    2007-07-01

    As is known each sea-going vessel is equipped with navigation, communication and other radio engineering facilities that serve to secure the safety of navigation and are chiefly operated at UHF-wave band. In developing these systems and calculating the energy potential for a necessary coverage range one should be well aware of the radio signal attenuation processes on a propagation path. The key parameter of this path is the (radio) wave attenuation factor V and its distance dependence V(R). A diversity of factors influencing the radio signal attenuation over the oceanic expanses, especially well pronounced and quite stable tropospheric ducts, and the lack of experimental data were the compelling reasons why the researchers of the Institute for Radiophysics and Electronics, NASU, had spent many years on comprehensive radiophysical investigations carried out in different regions of the Atlantic, Indian, Arctic and Pacific Oceans. The experimental data obtained allow creating the database of radio wave attenuation factor V.

  7. Radio wave propagation and acoustic sounding

    NASA Astrophysics Data System (ADS)

    Singal, S. P.

    Radio wave propagation of the decimetric and centimetric waves depends to a large extent on the boundary layer meteorological conditions which give rise to severe fadings, very often due to multipath propagation. Sodar is one of the inexpensive remote sensing techniques which can be employed to probe the boundary layer structure. In the paper a historical perspective has been given of the simultaneously conducted studies on radio waves and sodar at various places. The radio meteorological information needed for propagation studies has been clearly spelt out and conditions of a ray path especially in the presence of a ducting layer have been defined as giving rise to fading or signal enhancement conditions. Finally the potential of the sodar studies to obtain information about the boundary layer phenomena has been stressed, clearly spelling out the use of acoustic sounding in radio wave propagation studies.

  8. 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…

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Sjogren, William L.; Kliore, Arvydas J.; Luhmann, Janet G.; Brace, Larry H.

    1989-01-01

    The observation of S-band (2.3 GHz) radio scintillations in the ionosphere of Venus by the Pioneer Venus Orbiter is reported. In situ plasma measurements and propagation calculations show that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. It is suggested that these topside plasma irregularities are associated with the penetration of large-scale magnetic fields in the ionosphere. It is found that the disturbed plasma and the scintillations are a manifestation of high-dynamic solar wind interaction with the ionosphere.

  11. Magellan radio occultation measurements of atmospheric waves on Venus

    NASA Technical Reports Server (NTRS)

    Hinson, David P.; Jenkins, J. M.

    1995-01-01

    Radio occultation experiments were conducted at Venus on three consecutive orbits of the Magellan spacecraft in October 1991. Each occultation occurred over the same topography (67 deg N, 127 deg E) and at the same local time (22 hr 5 min), but the data are sensitive to zonal variations because the atmosphere rotates significantly during one orbit. Through comparisons between observations and predictions of standard wave theory, we have demonstrated that small-scale oscillations in retrieved temperature profiles as well as scintillations in received signal intensity are caused by a spectrum of vertically propagating internal gravity waves. There is a strong similarity between the intensity scintillations observed here and previous measurements, which pertain to a wide range of locations and experiment dates. This implies that the same basic phenomenon underlies all the observations and hence that gravity waves are a persistent, global feature of Venus' atmosphere. We obtained a fairly complete characterization of a gravity wave that appears above the middle cloud in temperature measurements on all three orbits. The amplitude and vertical wavelength are about 4 K and 2.5 km respectively, at 65 km. A model for radiative damping implies that the wave intrinsic frequency is approximately 2 x 10(exp 4) rad/sec, the corresponding ratio between horizontal and vertical wavelengths is approximately 100. The wave is nearly stationary relative to the surface or the Sun. Radiative attenuation limits the wave amplitude at altitudes above approximately 65 km, leading to wave drag on the mean zonal winds of about +0.4 m/sec per day (eastward). The sign, magnitude, and location of this forcing suggest a possible role in explaining the decrease with height in the zonal wind speed that is believed to occur above the cloud tops. Temperature oscillations with larger vertical wavelengths (5-10 km) were also observed on all three orbits, but we are able unable to interpret these

  12. 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.

  13. 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'.

  14. 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.

  15. Effects of multiple scattering on scintillation of transionospheric radio signals

    NASA Technical Reports Server (NTRS)

    Liu, C. H.; Yeh, K. C.; Youakim, M. Y.; Wernik, A. W.

    1974-01-01

    Recent development in the optical scintillation theory has been adapted to the ionospheric geometry in order to study the ionospheric scintillation phenomenon in the presence of multiple scattering. Under approximations well satisfied in typical ionospheres for a frequency above about 20 MHz, the first through fourth moment equations have been derived and some analytic solutions given. The fourth moment equation has also been solved numerically. The numerical results show clearly the occurrence of focusing and saturation phenomena. The new multiple-scatter effects are emphasized.

  16. Interplanetary scintillations of the radio source ensemble at the maximum of cycle 24 of solar activity

    NASA Astrophysics Data System (ADS)

    Chashei, I. V.; Shishov, V. I.; Tyul'bashev, S. A.; Subaev, I. A.

    2016-05-01

    The results of the interplanetary scintillation observations performed in the period of the maximum of solar activity from April 2013 to April 2014 on the BSA LPI radio telescope at the frequency 111MHz are presented. Fluctuations of the radio emission flux were recorded round the clock for all sources with a scintillating flux of more than 0.2 Jy falling in a strip of sky with a width of 50° over declinations corresponding to a 96-beam directional pattern of the radio telescope. The total number of sources observed during the day reaches 5000. The processing of the observational data was carried out on the assumption that a set of scintillating sources represents a homogeneous statistical ensemble. Daily two-dimensional maps of the distribution of the level of scintillations, whose analysis shows the strong nonstationarity and large-scale irregularity of the spatial distribution of solar wind parameters, were constructed. According to maps of the distribution of the level of scintillations averaged over monthly intervals, the global structure of the distribution of the solar wind was investigated in the period of the maximum of solar activity, which was found to be on the average close to spherically symmetric. The data show that on a spherically symmetric background an east-west asymmetry is observed, which indicates the presence of a large-scale structure of a spiral type in the solar wind.

  17. 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.

  18. The Propagation of Radio Waves

    NASA Astrophysics Data System (ADS)

    Budden, K. G.

    1988-08-01

    Preface; 1. The ionosphere and magnetosphere; 2. The basic equations; 3. The constitutive relations; 4. Magnetoionic theory I. Polarisation and refractive index; 5. Magnetoionic theory II. Rays and group velocity; 6. Stratified media. The booker quartic; 7. Slowly varying medium. The W.K.B. solution; 8. The Airy integral function and the Stokes phenomenon; 9. Integration by steepest descents; 10. Ray tracing in a loss-free stratified medium; 11. Reflection and transmission coefficients; 12. Ray theory results for isotropic ionosphere; 13. Ray theory results for anisotropic plasmas; 14. General ray tracing; 15. Full wave solutions for isotropic ionosphere; 16. Coupled wave eqations; 17. Coalescence of couling points; 18. Full wave methods for anisotropic stratified media; 19. Applications of full wave methods; Answers to problems; Bibliography; Index of definitions of the more important symbols; Subject and name index.

  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. Constraining the Vela Pulsar's Radio Emission Region Using Nyquist-limited Scintillation Statistics

    NASA Astrophysics Data System (ADS)

    Johnson, M. D.; Gwinn, C. R.; Demorest, P.

    2012-10-01

    Using a novel technique, we achieve ~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.

  1. 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.

  2. Ionospheric Scintillation at Low Frequencies: Broadband Spectra and Phase Measurements from Natural Radio Sources

    NASA Astrophysics Data System (ADS)

    Fallows, Richard A.; Forte, Biagio; Coles, William A.

    2016-04-01

    Observations of strong natural radio sources such as Cassiopeia A taken using the Low Frequency Array (LOFAR) centred on the Netherlands, and the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) in arctic Finland, over the frequency range 10-250 MHz show almost continual ionospheric scintillation. Dynamic spectra of these observations show scintillation varying from weak to strong scattering and the effects of refraction due to large-scale structure in the ionosphere can also be visible. Recent efforts have also attempted to measure phase scintillation in addition to the regular intensity measurements, using simultaneous low-resolution all-sky imaging, to confirm when strong refraction is seen. Delay-Doppler spectra (the two-dimensional power spectrum of a dynamic spectrum) sometimes show an arc structure, similar to the "scintillation arcs" reported from observations of interstellar scintillation, which can be used to model parameters such as the distance to the scattering "scree" and the velocity of the scattering medium transverse to the line of sight. These two parameters are inherently linked in modelling which means that one needs to be known before the other can be established accurately. The dense core of the LOFAR array has been used to take temporal cross-correlations between station pairs to establish a picture of the velocity field in the ionosphere; with KAIRA other supporting instrumentation can be used to estimate ionospheric velocities in nearby regions. These velocities are used to attempt to establish the altitudes dominating scattering due to the ionosphere.

  3. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  4. Scintillation of radio astronomical sources due to anisotropic inhomogeneities in the ionospheric plasma

    SciTech Connect

    Bezrodnyi, V.G.

    1988-02-01

    We have investigated the properties of scintillation of sources of cosmic radio emission due to inhomogeneities in the ionospheric F-region. The inhomogeneities are elongated along the geomagnetic field lines. We show that when the line of sight coincides with the magnetic field direction, we should observe an increase in the magnitude of the scintillation index. The amount of the increase, as well as the angular range in which it occurs, depend on the explicit shape of the spectrum of spatial scales of the inhomogeneities. We have given consideration to models which have been adopted in the literature for three-dimensional and two-dimensional anisotropy in the ionospheric turbulence. Based on this analysis, we propose a diagnostic method for the inhomogeneous ionospheric plasma. It is based on multifrequency measurements of the scintillation index of radio astronomical sources which culminate near the direction of the geomagnetic field lines at the latitude of the observing point. We establish the limits which are imposed on our proposed method because of the finite dimensions of the sources.

  5. Unusual radio and plasma wave phenomena observed in March 1991

    NASA Technical Reports Server (NTRS)

    Reiner, M. J.; Stone, R. G.; Fainberg, J.

    1992-01-01

    During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Some of these URAP observations cannot be explained by mechanisms usually attributed to interplanetary (IP) radio emissions and Langmuir wave activity and require other interpretations.

  6. HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations

    NASA Technical Reports Server (NTRS)

    Frey, A.; Gordon, W. E.

    1982-01-01

    Three observations of radio star intensity fluctuations at UHF are reported for HF ionospheric modification experiments carried out at the Arecibo Observatory. Two observations at 430 MHz and one at 1400 MHz suggest that the the thin phase screen theory is a good approximation to the observed power spectra. It is noted, however, that the theory has to be extended to include antenna filtering. This type of filtering is important for UHF radio star scintillations since the antenna usually has a narrow beamwidth. HF power densities of less than 37 microwatts/sq m incident on the ionosphere give rise to electron density irregularities larger than 13% of the ambient density (at 260 km) having scale sizes of approximately 510 m perpendicular to the geomagnetic field. The irregularities are found to form within 20-25 s after the HF power is turned on. The drift velocities of the irregularities can be estimated from the observed power spectra.

  7. 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.

  8. 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.

  9. The Scintillation and TEC Radio Instrument in Space (SCITRIS) Program at the Naval Research Laboratory

    NASA Astrophysics Data System (ADS)

    Bernhardt, P.; Siefring, C.; Huba, J.; Galysh, I.

    SCITRIS, a new space-based system to monitor total electron content (TEC) and ionospheric scintillations (IS), is scheduled for launch in late 2006. Two satellites, the Air Force S ace Test Program STPSAT1 and the Naval Postgraduate Schoolp NPSAT1, will host the SCITRIS instruments. The satellites will orbit at 560 km altitude with an inclination of 35 degrees. The CITRIS receiver on STPSAT1 will record signals from radio beacons o erating near 150, 400, 1067 and 2036 MHz.p The frequency pair 401.25 and 2036.25 MHz will be transmitted from the 50 ground transmitters that comprise the Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) system maintained by CNES in France. The frequencies 150.012, 400.032, and 1066.752 MHz will be transmitted using the Naval Research Laboratories' Coherent Electromagnetic Radio Tomography (CERTO) beacon from the NPSAT1 satellite. The NRL Langmuir probe will also be located on NPSAT1 to provide in situ electron density. The CITRIS receiver will process the measurements of complex amplitude from the multifrequency beacons to yield TEC and scintillation indices (S 4, ). Global maps of electron density and ionospheric irregularities will be produced using the SCITRIS instruments.

  10. 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.

  11. Global morphology of ionospheric F-layer scintillations using FS3/COSMIC GPS radio occultation data

    NASA Astrophysics Data System (ADS)

    Tsai, Lung-Chih; Su, Shin-Yi

    2016-07-01

    The FormoSat-3/ Constellation Observing System for Meteorology, Ionosphere and Climate (FS3/COSMIC) has been proven a successful mission on profiling and modeling of ionospheric electron density by the radio occultation (RO) technique. In this study we report FS3/COSMIC limb-viewing observations of the GPS L-band scintillation since mid 2006 and propose to study F-layer irregularity morphology. Generally the FS3/COSMIC has performed >1000 ionospheric RO observations per day. Most of these observations can provide limb-viewing profiles of S4 scintillation index at dual L-band frequencies. There are a few percentage of FS3/COSMIC RO observations having >0.08 S4 values on average. However, seven identified areas at Central Pacific Area (-20∘~ 20∘dip latitude, 160∘E~130∘W), South American Area (-20∘~ 20∘dip latitude, 100∘W~30∘W), African Area (-20∘~ 20∘dip latitude, 30∘W~50∘E), European Area (30∘~55∘N, 0∘~55∘E), Japan See Area (35∘~55∘N, 120∘~150∘E), Arctic Area (> 65∘dip latitude), and Antarctic Area (< -65∘dip latitude) have been designated to have much higher percentage of strong L-band RO scintillation. During these years in most of the last sunspot cycle from mid 2006 to end 2014 the climatology of scintillations, namely, its variations with each identified area, season, local time, magnetic activity and solar activity have been documented.

  12. 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.

  13. Optical imaging of airglow structure in equatorial plasma bubbles at radio scintillation scales

    NASA Astrophysics Data System (ADS)

    Holmes, J. M.; Pedersen, T.; Parris, R. T.; Stephens, B.; Caton, R. G.; Dao, E. V.; Kratochvil, S.; Morton, Y.; Xu, D.; Jiao, Y.; Taylor, S.; Carrano, C. S.

    2015-12-01

    Imagery of optical emissions from F-region plasma is one of the few means available todetermine plasma density structure in two dimensions. However, the smallest spatial scalesobservable with this technique are typically limited not by magnification of the lens or resolutionof the detector but rather by the optical throughput of the system, which drives the integrationtime, which in turn causes smearing of the features that are typically moving at speeds of 100m/s or more. In this paper we present high spatio-temporal imagery of equatorial plasma bubbles(EPBs) from an imaging system called the Large Aperture Ionospheric Structure Imager(LAISI), which was specifically designed to capture short-integration, high-resolution images ofF-region recombination airglow at λ557.7 nm. The imager features 8-inch diameter entranceoptics comprised of a unique F/0.87 lens, combined with a monolithic 8-inch diameterinterference filter and a 2x2-inch CCD detector. The LAISI field of view is approximately 30degrees. Filtered all-sky images at common airglow wavelengths are combined with magneticfield-aligned LAISI images, GNSS scintillation, and VHF scintillation data obtained atAscension Island (7.98S, 14.41W geographic). A custom-built, multi-constellation GNSS datacollection system was employed that sampled GPS L1, L2C, L5, GLONASS L1 and L2, BeidouB1, and Galileo E1 and E5a signals. Sophisticated processing software was able to maintainlock of all signals during strong scintillation, providing unprecedented spatial observability ofL band scintillation. The smallest-resolvable scale sizes above the noise floor in the EPBs, as viewed byLAISI, are illustrated for integration times of 1, 5 and 10 seconds, with concurrentzonal irregularity drift speeds from both spaced-receiver VHF measurements and single-stationGNSS measurements of S4 and σφ. These observable optical scale sizes are placed in thecontext of those that give rise to radio scintillation in VHF and L band signals.

  14. 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…

  15. Polycrystalline para-terphenyl scintillator adopted in a β- 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 β- 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 β- 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.

  16. Radio wave scattering in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    Current models for the 2-3 kHz emissions observed by the Voyager spacecraft in the outer heliosphere involve 2f(p) radiation generated near the termination shock or the heliopause. Radio wave scattering by solar wind density irregularities strongly affects observed sources of f(p) and 2f(p) emission in the inner heliosphere and the characteristics of astrophysical sources. In particular, the angular size, brightness temperature, and time variability of the source are strongly affected by scattering, thereby having major implications for the inferred size, energy budget, time variability, location, and nature of the source if scattering is ignored. This paper addresses whether scattering is important for interpreting the Voyager 2-3 kHz emissions. Quantitative calculations (with and without diffraction) are performed for the angular broadening of an outer heliospheric source as a function of path length, radiation frequency relative to f(p) and the spectrum of density irregularities. The effects of scattering in both the solar wind and the heliosheath are considered. Predictions for radial gradients in the source's apparent angular size and in the source's modulation index are presented. The calculations are compared with observations and the results discussed. First estimates suggest that scattering plausibly dominates the observed source size. The observed trend in modulation index with heliocentric distance is consistent with scattering being important and the source being in the outer heliosphere. Additional arguments for scattering being important are summarized.

  17. Gravity wave detection by GPS radio occultations

    NASA Astrophysics Data System (ADS)

    Schmidt, Torsten; Arras, Christina; De la Torre, Alejandro; Alexander, Peter; Llamedo, Pablo

    2016-07-01

    Gravity waves (GWs) play an important role for the general atmospheric circulation due to the related transport of energy and momentum between different regions of the atmosphere. The momentum mostly generated in the troposphere is transported to upper atmospheric levels where GWs break or dissipate and transfer their momentum to the background wind (GW drag). The deposit of GW momentum can occur in the complete altitude range from the upper troposphere-stratosphere, the mesosphere, and even in the thermosphere. A global observation of GW parameters (e.g. potential energy and vertical flux of absolute horizontal momentum) is only possible with satellite data. The radio occultation (RO) technique uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Atmospheric temperature profiles in the troposphere/stratosphere and ionospheric electron densities are derived with high vertical resolution. The GPS RO technique is sensitive to GWs with small ratios of vertical to horizontal wavelengths. In this presentation we give an overview about the derivation of GW parameters from RO temperature profiles, review some results of GW detection with RO data, and discuss the limitations of the RO technique. The focus of the presented results is (1) global GW activity in the upper troposphere and lower stratosphere for different seasons, (2) influence of the topography on GW activity from the troposphere to the ionosphere in the Andean region of South America, and (3) the variation of ionospheric sporadic E layers.

  18. 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.

  19. New methods for calculating short-wave radio paths

    NASA Astrophysics Data System (ADS)

    Popov, A. V.; Tsedilina, E. E.; Cherkashin, Iu. N.

    Recent research on the calculation of short-wave paths at IZMIRAN (the Soviet Institute for the Study of Terrestrial Magnetism, the Ionosphere, and the Propagation of Radio Waves) is reviewed. Particular attention is given to: (1) the development of approximate analytical methods for ray-tracing calculations and for determining the geometrical-optics characteristics of a radio signal in a horizontally irregular ionosphere; (2) investigations of the long-range and short-wave propagation of decametric waves; and (3) the development of a parabolic-equation method for considering diffraction and scattering in a medium with regular and random irregularities.

  20. 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.

  1. 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.

  2. Ionospheric Scintillation Explorer (ISX)

    NASA Astrophysics Data System (ADS)

    Iuliano, J.; Bahcivan, H.

    2015-12-01

    NSF has recently selected Ionospheric Scintillation Explorer (ISX), a 3U Cubesat mission to explore the three-dimensional structure of scintillation-scale ionospheric irregularities associated with Equatorial Spread F (ESF). ISX is a collaborative effort between SRI International and Cal Poly. This project addresses the science question: To what distance along a flux tube does an irregularity of certain transverse-scale extend? It has been difficult to measure the magnetic field-alignment of scintillation-scale turbulent structures because of the difficulty of sampling a flux tube at multiple locations within a short time. This measurement is now possible due to the worldwide transition to DTV, which presents unique signals of opportunity for remote sensing of ionospheric irregularities from numerous vantage points. DTV spectra, in various formats, contain phase-stable, narrowband pilot carrier components that are transmitted simultaneously. A 4-channel radar receiver will simultaneously record up to 4 spatially separated transmissions from the ground. Correlations of amplitude and phase scintillation patterns corresponding to multiple points on the same flux tube will be a measure of the spatial extent of the structures along the magnetic field. A subset of geometries where two or more transmitters are aligned with the orbital path will be used to infer the temporal development of the structures. ISX has the following broad impact. Scintillation of space-based radio signals is a space weather problem that is intensively studied. ISX is a step toward a CubeSat constellation to monitor worldwide TEC variations and radio wave distortions on thousands of ionospheric paths. Furthermore, the rapid sampling along spacecraft orbits provides a unique dataset to deterministically reconstruct ionospheric irregularities at scintillation-scale resolution using diffraction radio tomography, a technique that enables prediction of scintillations at other radio frequencies, and

  3. Scintillation correlation between forward and return spherical waves.

    PubMed

    Perlot, Nicolas; Giggenbach, Dirk

    2012-05-20

    According to the point-source point-receiver (PSPR) reciprocity, the received field remains equal when the positions of a point source and point receiver are interchanged. We extend the PSPR scenario to a finite receiver that spatially averages scintillation over its aperture. By use of weak-fluctuation theory, an analytical expression for the correlation coefficient between the received powers at both link ends is provided. The effects of turbulence profile, receiver aperture size, and central obscuration on the correlation are assessed. Because correlation is obtained to the detriment of antenna gain and aperture averaging, the net benefit of the channel reciprocity is highly scenario dependent. PMID:22614590

  4. Evidence for nonlinear wave-wave interactions in solar type III radio bursts

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Levedahl, W. K.; Lotko, W.; Gurnett, D. A.; Scarf, F. L.

    1986-01-01

    Evidence is presented that nonlinear wave-wave interactions occur in type III solar radio bursts. Intense, spiky Langmuir waves are observed to be driven by electron beams associated with type III solar radio bursts in the interplanetary medium. Bursts of 30-300 Hz (in the spacecraft frame) waves are often observed coincident in time with the most intense spikes of the Langmuir waves. These low-frequency waves appear to be long-wavelength ion acoustic waves, with wavenumber approximately equal to the beam resonant Langmuir wavenumber. Three possible interpretations of these observations are considered: modulational instability, parametric decay of the parent Langmuir waves to daughter ion acoustic and Langmuir waves, and decay to daughter electromagnetic waves and ion acoustic waves.

  5. Roles Played by Electrostatic Waves in Producing Radio Emissions

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    2000-01-01

    Processes in which electromagnetic radiation is produced directly or indirectly via intermediate waves are reviewed. It is shown that strict theoretical constraints exist for electrons to produce nonthermal levels of radiation directly by the Cerenkov or cyclotron resonances. In contrast, indirect emission processes in which intermediary plasma waves are converted into radiation are often favored on general and specific grounds. Four classes of mechanisms involving the conversion of electrostatic waves into radiation are linear mode conversion, hybrid linear/nonlinear mechanisms, nonlinear wave-wave and wave-particle processes, and radiation from localized wave packets. These processes are reviewed theoretically and observational evidence summarized for their occurrence. Strong evidence exists that specific nonlinear wave processes and mode conversion can explain quantitatively phenomena involving type III solar radio bursts and ionospheric emissions. On the other hand, no convincing evidence exists that magnetospheric continuum radiation is produced by mode conversion instead of nonlinear wave processes. Further research on these processes is needed.

  6. 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.

  7. 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.

  8. Synopsis of Mid-latitude Radio Wave Absorption in Europe

    NASA Technical Reports Server (NTRS)

    Torkar, K. M.; Friedrich, M.

    1984-01-01

    Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region are also plotted onto these charts.

  9. Trajectories of radio waves in linear layer with isometric inhomogeneities

    NASA Astrophysics Data System (ADS)

    Golynskiy, S. M.; Khlybov, G. N.

    1984-05-01

    The trajectories of radio waves in a statistically nonhomogeneous medium such as a linear ionospheric layer are estimated, taking into account their perturbation by local inhomogeneities. Assuming that the trajectories do remain in the plane of incidence, the deviation of the most probable trajectory from its unperturbed path in accordance with Snell's law is calculated for three models of wave diffusion as a Markov process (D- diffusion). The results are useful for design and operation of radio communication lines, calculation of the maximum usable frequency, and other applications.

  10. On the Possibility of Study of the External Solar Wind Thin Structure in Decameter Radio Waves

    NASA Astrophysics Data System (ADS)

    Olyak, M. R.

    2006-08-01

    The purpose of this work is to develop the research technique of the thin structure of outer solar wind in decameter waves. The extended medium model and Feynman path-integral method were applied for calculations of the cross - spectra of weak interplanetary scintillations. The temporary spectra W(f) and phase speed dispersion dependencies V(f) for the spherically symmetric (curves 1) and two-high-speed (curves 2) models of solar wind were calculated. The meanings of solar wind parameters were chosen so that the differences of temporary spectra for two models were minimal and laid within the limits of probable measurements errors ([S:f:S][Author ID2: at Fri Jul 14 10:28:00 2006 ] F[Author ID2: at Fri Jul 14 10:28:00 2006 ]ig. 1). It is shown that the supervision of scintillations on two spatially carried antennas and study of dispersion dependence of phase speed will allow to notice the presence of the accelerated flows on a beam of sight when the measurements on one antenna do not give the unequivocal answer to the question whether the flows of solar wind with various speeds are present in external areas of interplanetary medium. It is shown that by using of simultaneous measurements of temporary spectra and dispersion dependences of phase speed the detection of fast and slow solar wind flows and the definition of their parameters are possible in decameter radio waves.

  11. Embracing the Wave: Using the Very Small Radio Telescope to Teach Students about Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Fish, Vincent L.; Needles, M. M.; Rogers, A. E. E.; Doherty, M.; Minnigh, S.; Arndt, M. B.; Pratap, P.

    2010-01-01

    The Very Small Radio Telescope (VSRT) is a low-cost educational tool appropriate for laboratory demonstrations of the nature of radio waves and the principles of interferometry for use in both high school and undergraduate physics/astronomy classes. The system consists of small direct broadcast antenna dishes and other commercially available parts and can be assembled for under $500. Complete teaching units have been developed and tested by high school physics teachers to demonstrate radio wave transmission and exponential absorption though materials (Beer's law), the polarization of electromagnetic waves (Malus' law), the inverse square law, and interferometry. These units can be used to explore the properties of electromagnetic waves, including similarities and differences between radio and visible light, while challenging students' misconceptions about a wavelength regime that is important to both astronomy and everyday life. In addition, the VSRT can be used as a radio astronomical interferometer to measure the diameter of the Sun at 12 GHz. Full details, including a parts list, comprehensive assembly instructions, informational memos, teaching units, software, and conformance to national and Massachusetts educational standards, are available on the web at http://www.haystack.mit.edu/edu/undergrad/VSRT/index.html . Development of the VSRT at MIT Haystack Observatory is made possible through funding provided by the National Science Foundation.

  12. 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.

  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. 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)

  16. The Radio Wave Emission from Sgr A*

    NASA Astrophysics Data System (ADS)

    Beaklini, Pedro Paulo Bonetti

    2008-10-01

    SgrA* is a compact radio source, with radius smaller than 1 AU. Its position is coincident with the dynamic center of a star cluster that orbits the 4 million solar mass supermassive black hole found in the center of the Milky Way. SgrA* is surrounded by a complex of HII regions, with complex morphology, named SgrA. The variability of the SgrA* emission was observed at different wavelengths, as radio, infrared and X-rays, with timescales that range from hours to months. Recent observations using interferometric techniques have detected a quasiperiodicity in the radio light curve from SgrA*. In our work, we present the result of 43 GHz observations obtained with the Itapetinga radiotelescope, located in Atibaia, which aimed to detect this variability and verify the existence of a periodicity. Sgr B2, an HII complex near SgrA*, was used as a calibrator to eliminate any extrinsic variability. The obtained light curve is consistent with previous results reported in the literature, confirming the increase in the amplitude of the variability with frequency. Particularly, daily variability was found that is compatible with what was reported at 7 mm using VLBI techniques. The expected 106 days periodicity was not found in our data by the Jurkevich statistic method, which instead indicated the existence of a 90 day period. However, the superposition of the 7 mm data on a 106 day look similar to what was found from the 1.3 cm observations. Considering that the observations at 7 mm do not cover all the phases in the full cycle, more observations are needed to confirm the existence of a periodicity in the light curve.

  17. 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.

  18. Lightning location with variable radio wave propagation velocity

    NASA Astrophysics Data System (ADS)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Sugier, Jacqueline; Fullekrug, Martin

    2016-04-01

    Lightning discharges can be located by triangulation of their broadband electromagnetic pulses in long-baseline (~500 km) radio receiver networks. Here we apply the time of arrival difference (TOA) method to electric field recordings with a low frequency radio receiver array consisting of four stations in western Europe. The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for the TOA calculation and it is normally assumed to be equal to the speed of light. However, the radio wave propagation depends for example on the frequency, ground conductivity and the ionospheric height and small variations can cause location differences from hundreds to thousands of meters, as demonstrated in this study. The radio wave propagation from two VLF transmissions at 20.9 kHz and 23.4 kHz are compared. The results show that the apparent phase velocities are 0.6% slower and 0.5% faster than the speed of light respectively. As a result, a variable velocity is implemented in the TOA method using continuously recorded data on the 8th August 2014, when a mesoscale convective system developed over central France. The lightning locations inferred with a variable wave propagation velocity are more clustered than those using a fixed velocity. The distribution of the lightning velocities in a given geographic area fits a normal distribution that is not centred at the speed of light. As a result, representative velocities can be calculated for smaller regions to generate a velocity map over a larger area of enhanced lightning activity. These results suggest a connection with the ground elevation and/or surface conductivity that might have an impact on the observed wave propagation velocities.

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

    SciTech Connect

    Magdalenić, J.; Marqué, C.; Mierla, M.; Zhukov, A. N.; Rodriguez, L.; Krupar, V.; Maksimović, 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.

  20. 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.

  1. Cassini Radio Science Observations of Density Waves in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    McGhee, C. A.; French, R. G.; Rappaport, N. J.; Marouf, E. A.; Dawson, R.; Stack, K.

    2006-08-01

    Saturn's ring system is an elegant celestial mechanical laboratory for studying the interactions between a host of small and large moons, and the rings themselves. Resonances between the satellites and the ring particles result in spiral density waves whose detailed characteristics can be used to determine the physical properties of the rings. Over the past year, the Cassini Radio Science Team has obtained nearly a dozen exquisite radial profiles of the structure of Saturn's rings from occultations at three radio wavelengths (0.9 cm, 3 cm, and 12 cm), at sub-km resolution, after correction for the effects of diffraction. The optical depth profiles of the rings are replete with density waves produced by Mimas, Janus, Epimetheus, Prometheus, Pandora, and even smaller moons. Using wavelet decomposition as well as direct model fitting, we have determined the surface mass density and viscosity of the ring particles from weak (linear) density waves, primarily in the A ring. These are essential ingredients for dynamical models of the rings that include the effects of self-gravity and inelastic particle collisions. Future radio science occultation experiments throughout the Cassini orbital tour of Saturn will probe the rings at a range of ring opening angles, providing both additional measurements of density waves and other ring features.

  2. Remote sensing of irregularities in the equatorial ionosphere using the radio scintillation technique

    SciTech Connect

    Franke, S.J.

    1984-01-01

    Experimental measurements of signal level fluctuations (scintillation) on VHF and microwave signals from two geostationary communications satellites are studied in detail. The signals were recorded at an equatorial location which is almost directly beneath the satellites. The scintillation is caused by refraction and diffraction of the signals by variations of the refractive index in the Flayer of the ionosphere. This study is directed toward using the observed multifrequency scintillation to remotely sense the characteristics of the ionospheric irregularities. This is done by considering both statistical and deterministic models for the scintillation producing irregularities. The models are combined with existing propagation theory using analytical and numerical simulation techniques in order to predict the spatial and temporal characteristics of the multifrequency scintillation. Comparison with the observations is used to verify the models. Extensive use is made of numerical simulation. This makes it possible to study both weak and strong scintillations which occur simultaneously on the microwave and VHF frequencies, respectively. In all cases, the models are chosen to be consistent with results from other remote sensing techniques and in situ measurements. Geophysical implications of the results are discussed in light of what is known about equatorial irregularities from previous experimental and theoretical studies.

  3. 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

    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.

  4. Electron Transport by Radio Frequency Waves in Tokamak Plasmas

    SciTech Connect

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

    2009-11-26

    A relativistic kinetic description for momentum and spatial diffusion of electrons by radio frequency (RF) waves and non-axisymmetric magnetic field perturbations in a tokamak is formulated. The Lie perturbation technique is used to obtain a non-singular, time dependent evolution equation for resonant and non-resonant electron diffusion in momentum space and diffusion in configuration space. The kinetic equation for the electron distribution function is different from the usual quasilinear equations as it includes interactions that are non-Markovian. It is suitable for studying wave-particle interaction in present tokamaks and in ITER. A primary goal of RF waves, and, in particular, of electron cyclotron waves, in ITER is to control instabilities like the neoclassical tearing mode (NTM). Non-axisymmetric effects due to NTMs are included in the kinetic formalism.

  5. 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.

  6. Effect of Radio Frequency Waves on Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Sen, S.

    2015-11-01

    The effect of Radio Frequency waves on low frequency plasma instabilities and turbulence is studied. It is shown that the ponderomotive force can stabilize or destabilize instabilities depending on the power deposition profile and no RF induced flow generation hypothesis is required. Its possible consequence on space and fusion plasma will be discussed. Collaborations with George Vahala from William & Mary, Julio Martinell from UNAM and Atsushi Fukuyama from Kyoto University are acknowledged.

  7. 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.

  8. 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.

  9. Wave optics-based LEO-LEO radio occultation retrieval

    NASA Astrophysics Data System (ADS)

    Benzon, Hans-Henrik; Høeg, Per

    2016-06-01

    This paper describes the theory for performing retrieval of radio occultations that use probing frequencies in the XK and KM band. Normally, radio occultations use frequencies in the L band, and GPS satellites are used as the transmitting source, and the occultation signals are received by a GPS receiver on board a Low Earth Orbit (LEO) satellite. The technique is based on the Doppler shift imposed, by the atmosphere, on the signal emitted from the GPS satellite. Two LEO satellites are assumed in the occultations discussed in this paper, and the retrieval is also dependent on the decrease in the signal amplitude caused by atmospheric absorption. The radio wave transmitter is placed on one of these satellites, while the receiver is placed on the other LEO satellite. One of the drawbacks of normal GPS-based radio occultations is that external information is needed to calculate some of the atmospheric products such as the correct water vapor content in the atmosphere. These limitations can be overcome when a proper selected range of high-frequency waves are used to probe the atmosphere. Probing frequencies close to the absorption line of water vapor have been included, thus allowing the retrieval of the water vapor content. Selecting the correct probing frequencies would make it possible to retrieve other information such as the content of ozone. The retrieval is performed through a number of processing steps which are based on the Full Spectrum Inversion (FSI) technique. The retrieval chain is therefore a wave optics-based retrieval chain, and it is therefore possible to process measurements that include multipath. In this paper simulated LEO to LEO radio occultations based on five different frequencies are used. The five frequencies are placed in the XK or KM frequency band. This new wave optics-based retrieval chain is used on a number of examples, and the retrieved atmospheric parameters are compared to the parameters from a global European Centre for Medium

  10. The propagation of radio waves: The theory of radio waves of low power in the ionosphere and magnetosphere

    NASA Astrophysics Data System (ADS)

    Budden, K. G.

    The effect of the ionized regions of the earth's atmosphere on radio wave propagation is comprehensively treated. After an introductory consideration of the terrestrial ionosphere and magnetosphere, wave propagation in ion plasmas, and their disturbances, attention is given to basic equations for the consideration of propagation effects, such constitutive relations as the Lorentz polarization term and the Debye length, the roles of polarization and refractive index in magnetoionic theory, rays and group velocity, the Booker quartic in stratified media, and the 'WKB' solutions. Further topics encompass the Airy integral function and the Stokes phenomenon, ray tracing in a loss-free stratified medium, ray theory and full wave solution results for an isotropic ionosphere, and full wave methods for anisotropic stratified media and their applications.

  11. The role of the magnetosphere in satellite and radio-star scintillation

    NASA Technical Reports Server (NTRS)

    Booker, H. G.

    1975-01-01

    A theory is developed to account for the scintillation phenomenon observed in equatorial regions when using communications satellites in the SHF band. The same theory is also used qualitatively to explain strong scintillations in the VHF band. Instead of confining irregularities to a narrow interval of height in the F-region and assuming that they are strong, the alternative hypothesis is used that the irregularities are weak but extend from the F-region upwards into the magnetosphere. It is suggested that the irregularities are field-aligned and extend at least up to an L-shell of 1.3 and possibly up to 2 or more.

  12. 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.

  13. Interpretation of gravity wave signatures in GPS radio occultations

    NASA Astrophysics Data System (ADS)

    Alexander, P.; de la Torre, A.; Llamedo, P.

    2008-08-01

    The horizontal averaging of global positioning system radio occultation retrievals produces an amplitude attenuation and phase shift in any plane gravity wave, which may lead to significant discrepancies with respect to the original values. In addition, wavelengths cannot be straightforwardly inferred due to the observational characteristics. If the waves produce small departures from spherical symmetry in the background atmosphere and under the assumption that the refractivity kernel may be represented by a delta function, an analytical expression may be derived in order to find how the retrieved amplitudes become weakened (against the original ones). In particular, we study the range of waves that may be detected and the consequent reduction in variance calculation, which is found to be around 19%. A larger discrepancy was obtained when comparing an occultation variance with the one computed from a numerical simulation of that case. Wave amplitudes can be better resolved when the fronts are nearly horizontal or when the angle between the occultation line of sight and the horizontal component of the wave vector approaches π/2. Short horizontal scale waves have a high probability of becoming attenuated or of not being detected at all. We then find geometrical relations in terms of the relative orientation between waves and sounding, so as to appropriately interpret wavelengths extracted from the acquired data. Only inertio-gravity waves, which exhibit nearly horizontal fronts, will show small differences between detected and original vertical wavelengths. Last, we analyze the retrieval effect on wave phase and find a shift between original and detected wave that generally is nonzero and approaches π/4 for the largest horizontal wavelengths.

  14. Propagation of radio frequency waves through density filaments

    NASA Astrophysics Data System (ADS)

    Ram, Abhay K.; Hizanidis, Kyriakos

    2015-12-01

    In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments are routinely observed in the scrape-off layer. In this paper we develop an analytical formalism for the scattering of radio frequency waves by filaments which are cylindrical with their major axis aligned along the toroidal magnetic field lines. Since the magnitude of the ratio of the density inside the filaments to the background density is generally of order 1, the geometric optics approximation cannot be used to describe the scattering. A full-wave model is formulated which assumes that the plasma is cold and that the plasma in the cylindrical filament has uniform density. The background plasma, in which the filament is present, is also assumed to be cold and uniform. The theoretical framework applies to the scattering of any plasma wave.

  15. Trends and Periodicities In Nighttime Lf Radio Wave Reflection Heights

    NASA Astrophysics Data System (ADS)

    Kürschner, D.; Jacobi, Ch.

    The nighttime reflection height of low-frequency (LF) radio waves at oblique inci- dence is measured at Collm Observatory using 1.8 kHz sideband phase comparisons of the sky-wave and the ground wave of a commercial 177 kHz LF transmitter. The measurements have been carried out continuously since 1983, now allowing the anal- ysis of trends and regular variations of the reflection height. In the time series is found a) a long-term negative trend and b) a solar cycle dependence, both confirming ear- lier measurements and theoretical estimations. Moreover, a significant oscillation of quasi-biennial period is visible in LF reflection heights, indicating a reaction of the midlatitude mesosphere/lower thermosphere region on the equatorial QBO.

  16. Propagation of radio frequency waves through density filaments

    SciTech Connect

    Ram, Abhay K.; Hizanidis, Kyriakos

    2015-12-10

    In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments are routinely observed in the scrape-off layer. In this paper we develop an analytical formalism for the scattering of radio frequency waves by filaments which are cylindrical with their major axis aligned along the toroidal magnetic field lines. Since the magnitude of the ratio of the density inside the filaments to the background density is generally of order 1, the geometric optics approximation cannot be used to describe the scattering. A full-wave model is formulated which assumes that the plasma is cold and that the plasma in the cylindrical filament has uniform density. The background plasma, in which the filament is present, is also assumed to be cold and uniform. The theoretical framework applies to the scattering of any plasma wave.

  17. Scattering of radio frequency waves by density fluctuations

    NASA Astrophysics Data System (ADS)

    Ram, A. K.; Hizanidis, K.; Ioannidis, Z.; Tigelis, I.

    2015-11-01

    The scattering of radio frequency waves by density fluctuations in magnetized fusion plasmas is studied theoretically and computationally. For coherent fluctuations, such as filaments in the edge region, we use a full-wave model for which the theory is similar to that for Mie scattering of electromagnetic waves by dielectric objects. The filaments are considered to be cylindrical with their axes aligned along the magnetic field. The results from the theoretical model are compared with numerical simulations using COMSOL. The simulations are extended to plasma conditions that are beyond the scope of the theoretical model, e.g., multiple filaments and filaments with density gradients. For incoherent planar fluctuations, which can be either in the core of the plasma or in the edge region, our theory is based on the Kirchhoff approach in tandem with Huygen's principle. The coherent and incoherent fluctuations scatter the incident plane wave, as well as couple some of the power to different plasma waves. The scattered spectrum is affected by the size of the fluctuations, the frequency, and the direction of propagation of the incident wave.

  18. Chaotic behavior of ionospheric turbulence from scintillation measurements

    SciTech Connect

    Bhattacharyya, A. )

    1990-05-01

    Ionospheric amplitude and phase scintillation data have been analyzed to estimate the information dimension associated with the attractor of the system. For weak scintillations, both amplitude and phase data yield identical results which demonstrate that spatial fluctuations of electron density in the ionosphere may be characterized by a few degrees of freedom. Stronger scintillations are attributed to steepened density irregularities which cause focusing of the incident radio wave. This results in the amplitude scintillations exhibiting higher dimensional chaos but spatial fluctuations in ionospheric density still involve low dimensional chaos.

  19. 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.

  20. Digital measurements of LF radio wave absorption in the lower ionosphere and inferred gravity wave activity

    NASA Astrophysics Data System (ADS)

    Lastovicka, J.; Boska, J.; Buresova, D.

    1993-10-01

    Low frequency (LF) radio wave absorption in the lower ionosphere has been measured at Pruhonice (approximately 50 deg N) since 1957. A new digital computer-controlled measuring-recording-processing system was introduced in 1988. The A3 method of radio wave absorption measurement, the measuring equipment used for the digital measurements at 270 kHz, is briefly described. The digital nighttime LF A3 measurements allow the use of absorption data for studying and monitoring the gravity wave activity in the upper middle atmosphere in the period range 10 min-3(2) hours. The resulting gravity wave spectra are as expected even though their shapes vary. Individual period bands sometimes exhibit a similar general pattern of variability in gravity wave activity (winter 1990), while in other intervals we observe a shift of gravity wave energy from one period band to another (winter 1991). No strong, pronounced and consistent response to strong geomagnetic storms and midwinter stratospheric warming is found. An apparent seasonal variation with winter minima observed in shorter-period gravity wave activity is an artefact of the changing length of the night. There is no significant seasonal variation of gravity wave activity in the analysed data. The method is very cheap -- the results are a by-product of measurements made for ionospheric purposes.

  1. Spectral broadening and phase scintillation measurements using interplanetary spacecraft radio links during the peak of solar cycle 23

    NASA Astrophysics Data System (ADS)

    Morabito, David D.

    2009-12-01

    When an interplanetary spacecraft is in a solar superior conjunction configuration, the received radio signals are degraded by several effects that generally increase in magnitude as the angle between the spacecraft and the Sun (Sun-Earth-Probe or SEP angle) decreases as viewed by a terrestrial tracking station. During periods of quiescent solar activity, phase scintillation and spectral broadening follow well-defined trends as a function of solar impact distance (SEP angle) and link frequency. During active solar periods, the magnitudes of these effects increase above background levels predicted by the quiet period models. Several such events were observed during the solar superior conjunction of the Cassini spacecraft during the peak of solar cycle 23 in May 2000. Pronounced features in the spectral broadening data above the quiet background appear to be associated with Coronal Mass Ejections (CMEs), and last for extended periods of time ranging from ˜30 min to ˜4 h. These features are coincident with periods of increased activity seen in the region of the spacecraft signal source on coronal white light images, and tend to be related or matched with EIT flare events and possibly long-duration flare events seen in satellite X-ray data. Several such features were captured in the May 2000 Cassini solar conjunction phase scintillation and spectral broadening data at X band (8.4 GHz) and Ka band (32 GHz) radio frequencies, and are presented here. Such characterizations are beneficial in understanding the impact of such events in future interplanetary communication scenarios during solar conjunction periods.

  2. Gyrokinetic simulation on the effect of radio frequency waves on ion-temperature-gradient-driven modes

    NASA Astrophysics Data System (ADS)

    Imadera, K.; Kishimoto, Y.; Sen, S.; Vahala, G.

    2016-02-01

    The ion-temperature-driven modes are studied in the presence of radio frequency waves by the use of the Gyro-Kinetic simulation Code. It is shown that the radio frequency waves through the ponderomotive force can stabilise the ion-temperature-gradient instabilities and contrary to the usual belief no radio frequency wave-induced flow generation hypothesis is required. This might be a major way to create a transport barrier in the fusion energy generation.

  3. Searching for Correlated Radio Transients & Gravitational Wave Bursts

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    We will discuss an ongoing multi-messenger search for transient radio pulses and gravitational wave bursts. This work is being conducted jointly by the Long Wavelength Array (LWA) and the LIGO Scientific Collaboration (LSC). A variety of astrophysical sources can produce simultaneous emission of gravitational waves and coherent low-frequency electromagnetic radiation. The primary common source motivating this work is the merger of neutron star binaries for which the LWA and LSC instruments have comparable sensitivity. Additional common sources include supernovae, long timescale GRBs and cosmic string cusp events. Data taken by both instruments can be compared to search for correlated signals. Identification of correlated signals can be used to increase the sensitivity of both instruments. We will summarize the coincident observations which have already been conducted and outline plans for future work. We will describe the process being used for synthesizing these data set and present preliminary results.

  4. 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)

  5. Comparison of two phase scintillation estimators for GPS data obtained from High Latitudes.

    NASA Astrophysics Data System (ADS)

    Mushini, S. C.; Thayyil, J. P.; Langley, R. B.; MacDougall, J. W.

    2009-05-01

    Radio waves propagating through small scale plasma density irregularities produce fluctuations in both amplitude and phase of the signal. These fluctuations are called ionospheric scintillations. Due to their spatial diversity, GPS satellites allow scintillation measurement from different azimuthal sectors. Reliability of derived scintillation indices depend on the scintillation estimators used. Here we compare two different estimators for phase scintillations for data obtained from Canadian High Arctic Ionospheric Network (CHAIN) GPS receivers at high latitudes. These stations are specifically chosen to represent polar cap, near to the auroral boundary, and sub-auroral regions . Results of the comparison and its implications will be discussed.

  6. 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.

  7. 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

  8. 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.

  9. Optical detection of radio waves through a nanomechanical transducer.

    PubMed

    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 800 pV Hz-1/2 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 60 pV Hz-1/2 when balanced by choosing an electromechanical cooperativity of ~150 with an optical power of 1 mW. The noise temperature of the membrane is divided by the cooperativity. For the highest observed cooperativity of 6,800, this leads to a projected noise temperature of 40 mK and a sensitivity limit of 5 pV Hz-1/2. Our approach to

  10. Solar Corona and plasma effects on Radio Frequency waves

    NASA Astrophysics Data System (ADS)

    Nkono, C.; Rosenblatt, P.; Dehant, V. M.

    2009-12-01

    Solar corona (plasma) effects on radio signal waves for three different frequency bands S (2.3 GHz), X (8.4 GHz), and Ka (32 GHz), currently used to track probes in the solar system, have been computed using different models of the total electron content (TEC) along the propagation path between the Earth and Mars. The Earth-Mars-Sun configuration has been obtained from the planetary ephemerides DE421 (using SPICE kernels) for the period from September 2004 to September 2006. This configuration is expressed as a function of the Sun-Earth-Probe (SEP) angles (the probe being in close orbit to Mars). We used the TEC values provided by the different models proposed in the literature in order to estimate the TEC along the propagation path (STEC, for Slant TEC). From these model-dependent STEC estimates, the time delay on the wave propagation as well as the associated frequency shift with a 10 seconds sampling time have been obtained for each of the three frequency bands. For the X-band mostly used in radio science, we have obtained estimates differing by up to several orders of magnitude due to the different STEC values derived from different models of TEC. For example, if the propagation path passes near the Sun such that SEP angle is 1.55° the STEC is ranging from 4.6x1020 electron/m2 to 6.07x1016 electron/m2, which corresponds to a time delay range between 0.87 μs and 1.15x10-4 μs, respectively. For SEP angles between 2° and 8°, the range of the different time delay values reduces to 2.8x10-1 μs and becomes as small as 1.6x10-2 μs for SEP angles larger than 8° (1x10-2 μs is about the order of magnitude of the radioscience instrument precision). These results show that the correction of the solar corona effect on radio frequency waves can be reliably done on usual X-band tracking data of spacecraft for SEP angles >12°, but should be use with caution for lower SEP angles, especially lower than 2°.

  11. Waves in the Martian Atmosphere: Results from MGS Radio Occultations

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Hinson, D. P.; Tyler, G. L.

    1999-01-01

    Temperatures retrieved from Mars Global Surveyor radio occultations have been searched for evidence of waves. Emphasis has been on the initial series of occultations between 29 deg N and 64 deg S, obtained during the early martian southern summer, L(sub s) = 264 deg - 308 deg. The profiles exhibit an undulatory behavior that is suggestive of vertically propagating waves. wavelengths approximately 10 km are often dominant, but structure on smaller scales is evident. The undulatory structure is most pronounced between latitudes 29 deg N and 10 deg S, usually in regions of "interesting" topography, e.g., in the Tharsis region and near the edge of Syrtis Major. Several temperature profiles, particularly within 30 deg of the equator, exhibit lapse rates that locally become superadiabatic near the 0.4-mbar level or at higher altitudes. This implies that the waves are "breaking" and depositing horizontal momentum into the atmosphere. Such a deposition may play an important role in modulating the atmospheric winds, and characterizing the spatial and temporal distribution of these momentum transfers can provide important clues to understanding how the global circulation is maintained.

  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. Studies of the propagation of Low Frequency (LF) radio waves

    NASA Astrophysics Data System (ADS)

    Warrington, E. M.; Jones, T. B.

    1993-05-01

    Low frequency (30-300 kHz) radio waves can propagate to great distances with little attenuation in the cavity formed by the earth and the ionosphere. Because of the relatively high frequency at LF, many active propagation modes can occur between the transmitter and receiver. Changes in the ionospheric conductivity or reflection height can influence the phase and amplitude of these modes and, hence, produce mutual interference. Because of these interference effects, the propagation is less stable than at VLF and the received field strength becomes more difficult to predict. In the present investigation, the WAVEHOP program was employed in conjunction with a range of ionospheric models to estimate the receiver field strength over a number of experimental paths. The predicted values were compared with those measured in an attempt to validate the ionospheric models and the method of calculation.

  16. Annual report 1992/93, FOA 38. Radio systems and wave propagation

    NASA Astrophysics Data System (ADS)

    Mildh, I. M.

    1994-01-01

    The main objective of the division of Radio Systems and Wave Propagation is to carry out research and development in the field of secure and robust radio communications for Sweden's national defense. This is the Annual Report for fiscal year 1992/93 of the Division of Radio Systems and Wave Propagation. The division is responsible for research and development of secure radio communication for information transmission. We are also responsible for wave propagation research within a frequency range from LF to SHF. We carry out applied research in fields like antijamming systems, modulation, error correcting codes, wave propagation and digital signal processing. The wave propagation research is carried out by basic research so the demands from new techniques and new radio systems for accurate propagation models can be achieved.

  17. Worst-Case GPS Scintillations on the Ground Estimated from Radio Occultation Observations of FORMOSAT-3/COSMIC During 2007-2014

    NASA Astrophysics Data System (ADS)

    Liu, J. Y.; Chen, S. P.; Yeh, W. H.; Tsai, H. F.; Rajesh, P. K.

    2016-07-01

    The FORMOSAT-3/COSMIC (F3/C) satellite probes the S4 scintillation index profile of GPS signals by using the radio occultation (RO) technique. In this study, for practical use on the Earth's surface, a method is developed to convert and integrate the probed RO S4 index, so obtaining the scintillation on the ground. To estimate the worst case, the maximum value on each profile probed by F3/C, which is termed S4max, is isolated. The isolated data are further used to construct the global three-dimensional distributions of S4max for various local times, seasons, solar activities, and locations. The converted S4max for the first time estimates the global distribution of ionospheric scintillations in the GPS L1 band C/A code signal on the ground. The results show that the worst-case scintillations appear within the low-latitude region of ±30°N, peaking around ±20°N magnetic latitude; they begin at 1900 MLT, reach their maximum at 2100 MLT, and vanish by about 0200-0300 MLT. The most pronounced low-latitude scintillation occurs over the South American and African sectors.

  18. Worst-Case GPS Scintillations on the Ground Estimated from Radio Occultation Observations of FORMOSAT-3/COSMIC During 2007-2014

    NASA Astrophysics Data System (ADS)

    Liu, J. Y.; Chen, S. P.; Yeh, W. H.; Tsai, H. F.; Rajesh, P. K.

    2016-01-01

    The FORMOSAT-3/COSMIC (F3/C) satellite probes the S4 scintillation index profile of GPS signals by using the radio occultation (RO) technique. In this study, for practical use on the Earth's surface, a method is developed to convert and integrate the probed RO S4 index, so obtaining the scintillation on the ground. To estimate the worst case, the maximum value on each profile probed by F3/C, which is termed S4max, is isolated. The isolated data are further used to construct the global three-dimensional distributions of S4max for various local times, seasons, solar activities, and locations. The converted S4max for the first time estimates the global distribution of ionospheric scintillations in the GPS L1 band C/A code signal on the ground. The results show that the worst-case scintillations appear within the low-latitude region of ±30°N, peaking around ±20°N magnetic latitude; they begin at 1900 MLT, reach their maximum at 2100 MLT, and vanish by about 0200-0300 MLT. The most pronounced low-latitude scintillation occurs over the South American and African sectors.

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

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Belczynski, K.; Betzwieser, J.; Beyersdorf, P. T.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bogenstahl, J.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burmeister, O.; Busby, D.; Butler, W. E.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Carter, K.; Casey, M. M.; Castaldi, G.; Cepeda, C.; Chalkey, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Clark, J.; Cochrane, P.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Conte, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fejer, M. M.; Finn, L. S.; Fiumara, V.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Ganezer, K. S.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Howell, E.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Matta, V.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McNabb, J. W. C.; McWilliams, S.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Newton, G.; Nishizawa, A.; Nocera, F.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Parameswariah, C.; Patel, P.; Pedraza, M.; Penn, S.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H.; Plissi, M. V.; Postiglione, F.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rainer, N.; Rakhmanov, M.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Regimbau, T.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de La Jordana, L. Sancho; Sandberg, V.; Sanders, G. H.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Sazonov, A.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Sidles, J. A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Somiya, K.; Strain, K. A.; Strom, D. M.; Stuver, A.; Summerscales, T. Z.; Sun, K.-X.; Sung, M.; Sutton, P. J.; Takahashi, H.; Tanner, D. B.; Tarallo, M.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Ungarelli, C.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; van Putten, M.; Varvella, M.; Vass, S.; Vecchio, A.; Veitch, J.; Veitch, P.; Villar, A.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Ward, H.; Ward, R.; Watts, K.; Webber, D.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, S.; Wette, K.; Whelan, J. T.; Whitbeck, D. M.; Whitcomb, S. E.; Whiting, B. F.; Wiley, S.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Wilmut, I.; Winkler, W.; Wipf, C. C.; Wise, S.; Wiseman, A. G.; Woan, G.; Woods, D.; Wooley, R.; Worden, J.; Wu, W.; Yakushin, I.; Yamamoto, H.; Yan, Z.; Yoshida, S.; Yunes, N.; Zanolin, M.; Zhang, J.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M.; Zur Mühlen, H.; Zweizig, J.; Kramer, M.; Lyne, A. G.

    2007-08-01

    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 GEO 600 gravitational wave detectors. The data from both runs have been combined coherently to maximize 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 2.6×10-25 for PSR J1603-7202, and the equatorial ellipticity of PSR J2124 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.

  20. Nonextensivity effect on radio-wave transmission in plasma sheath

    NASA Astrophysics Data System (ADS)

    Mousavi, A.; Esfandiari-Kalejahi, A.; Akbari-Moghanjoughi, M.

    2016-04-01

    In this paper, new theoretical findings on the application of magnetic field in effective transmission of electromagnetic (EM) waves through a plasma sheath around a hypersonic vehicle are reported. The results are obtained by assuming the plasma sheath to consist of nonextensive electrons and thermal ions. The expressions for the electric field and effective collision frequency are derived analytically in the framework of nonextensive statistics. Examination of the reflection, transmission, and absorption coefficients regarding the strength of the ambient magnetic field shows the significance of q-nonextensive parameter effect on these entities. For small values of the magnetic field, the transmission coefficient increases to unity only in the range of - 1 < q < 1 . It is also found that the EM wave transmission through the nonextensive plasma sheath can take place using lower magnetic field strengths in the presence of superthermal electrons compared with that of Maxwellian ones. It is observed that superthermal electrons, with nonextensive parameter, q < 1, play a dominant role in overcoming the radio blackout for hypersonic flights.

  1. Combined X-Ray and mm-Wave Observations of Radio Quiet Active Galaxies

    NASA Astrophysics Data System (ADS)

    Behar, E.

    2016-06-01

    A connection between the X-ray and radio sources in radio quiet active galaxies (AGNs) will be demonstrated. High radio frequency, i.e., mm-wave observations are promising probes of the X-ray emitting inner regions of the accretion disks in radio quiet AGNs. An argument for simultaneous observations in X-rays and in mm waves will be made, in order to promote these as one of the future science goals of X-ray and AGN astronomy in the next decade. Preliminary results from an exploratory campaign with several space and ground based telescopes will be presented.

  2. Multipath propagation of low-frequency radio waves inferred from high-resolution array analysis

    NASA Astrophysics Data System (ADS)

    Füllekrug, Martin; Smith, Nathan; Mezentsev, Andrew; Watson, Robert; Astin, Ivan; Gaffet, Stéphane; Evans, Adrian; Rycroft, Michael

    2015-11-01

    The low-frequency radio sky shows the locations of electromagnetic radio sources with a characteristic dilution of precision. Here we report a thorough high-resolution analysis of radio waves from low-frequency (˜20-150 kHz) radio communication transmitters which are recorded with a small aperture array of radio receivers during the day. It is found that the observed dilution of precision results from the array geometry of the radio receivers, a birefringent wave propagation, and the correlated multipath propagation of low-frequency radio waves. The influence of the array geometry on the dilution of precision is reduced by taking into account the impulse response of the array. This procedure reveals for the very first time the splitting of one single radio source into two distinct source locations separated by ˜0.2°-1.9° which result from a birefringent wave propagation. The two locations are yet more clearly identified by using the polarity of the modulated wave number vectors of the radio waves. This polarity is also used to quantify the dilution of precision arising from correlated multipath propagation which is discriminated against wave number fluctuations arising from the timing accuracy of the radio receivers. It is found that ˜69% of the wave number variability is of natural origin and ˜31% originates from the timing accuracy of the receivers. The wave number variability from correlated multipath propagation results in a standard deviation ˜2-8% relative to the source location. This compact measurement of correlated multipath propagation is used to characterize the uncertainty of source locations in the radio sky. The identification of correlated multipath propagation strongly suggests the existence of very fast processes acting on time scales <1 ms in the D region ionosphere with physically meaningful effects on low-frequency radio wave propagation. This important result has implications for practical applications in that the observed multipath

  3. 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

  4. 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.

  5. Stratospheric gravity wave momentum flux from radio occultations

    NASA Astrophysics Data System (ADS)

    Schmidt, T.; Alexander, P.; Torre, A.

    2016-05-01

    Triples of GPS radio occultation (RO) temperature data are used to derive horizontal and vertical gravity wave (GW) parameters in the stratosphere between 20 km and 40 km from which the vertical flux of horizontal momentum is determined. Compared to previous studies using RO data, better limiting values for the sampling distance (Δd≤250 km) and the time interval (Δt≤15 min) are used. For several latitude bands the mean momentum fluxes (MFs) derived in this study are considerably larger than MF from other satellite missions based on horizontal wavelengths calculated between two adjacent temperature profiles along the satellite track. Error sources for the estimation of MF from RO data and the geometrical setup for the applied method are investigated. Another crucial issue discussed in this paper is the influence of different background separation methods to the final MF. For GW analysis a measured temperature profile is divided into a fluctuation and a background and it is assumed that the fluctuation is caused by GWs only. For the background separation, i.e., the detrending of large-scale processes from the measured temperature profile, several methods exist. In this study we compare different detrending approaches and for the first time an attempt is made to detrend RO data with ERA-Interim data from the European Centre for Medium-Range Weather Forecasts. We demonstrate that the horizontal detrending based on RO data and ERA-Interim gives more consistent results compared with a vertical detrending.

  6. Stratospheric gravity wave momentum fluxes from radio occultations

    NASA Astrophysics Data System (ADS)

    Schmidt, Torsten; Wickert, Jens; De la Torre, Alejandro; Alexander, Peter; Llamedo, Pablo; Ramezani Ziarani, Maryam

    2016-07-01

    Triples of GPS radio occultation (RO) temperature data are used to derive horizontal and vertical gravity wave (GW) parameters in the stratosphere between 20 km and 40 km from which the vertical flux of horizontal momentum is determined. Compared to previous studies using RO data better limiting values for the sampling distance (Δd<250 km) and the time interval (Δt<15 minutes) are used. For several latitude bands the mean momentum fluxes (MF) derived in this study are considerable larger than MF from other satellite missions based on horizontal wavelengths calculated between two adjacent temperature profiles along the satellite track. Error sources for the estimation of MF from RO data and the geometrical setup for the applied method is investigated. Another crucial issue discussed in the presentation is the influence of different background separation methods to the final MF. For GW analysis a measured temperature profile is divided into a fluctuation and a background and it is assumed that the fluctuation is caused by GWs only. For the background separation, i.e. the detrending of large-scale processes from the measured temperature profile, several methods exist. In this study we compare different detrending approaches including a new attempt by detrending RO data with ERA-Interim data from the European Centre for Medium-Range Weather Forecasts. We demonstrate that the horizontal detrending based on RO data and ERA-Interim gives more consistent results compared with a vertical detrending.

  7. The CERTO and CITRIS Instruments for Radio Scintillation and Electron Density Tomography from the C/NOFS, COSMIC, NPSAT1 and STPSAT1 Satellites

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Siefring, C. L.

    2004-05-01

    A new constellation of radio beacon and radio beacon receivers will be providing global measurements of radio scintillations and total electron content (TEC) for near real time measurements of the ionosphere. This constellation is comprised of the NRL Coherent Electromagnetic Radio Tomography (CERTO) beacons on the Communications/Navigation Forecast Outage System (C/NOFS) satellite, the six Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) satellites, and the Naval Postgraduate (NPSAT1) Satellite. These satellites will be launched in the time period of 2004 through 2006. The CERTO beacons operating at 150.012, 400.032, and 1066.752 MHz will be transmitting to ground receivers located in chains to acquire TEC data for computerized ionospheric tomography (CIT). In addition, in early 2006 a five frequency receiver will be placed in low earth orbit with the United States Air Force Space Test Program (STPSAT1) satellite. This CITRIS receiver will use radio beacon transmissions from the French DORIS network of ground beacons at 401.25 and 2036.25 MHz and space-based beacons at 150, 400 and 1067 MHz to measure the earth's ionosphere. On board tracking software will lock onto Doppler shifted frequencies to determine total electron content (TEC) and scintillation parameters. The STPSAT1 will be launched along with a companion satellite (NPSAT1) which carries the CERTO radio beacon and a Langmuir probe. All of the CERTO beacons as well as the ionospheric sensors on STPSAT1 and NPSAT1 are being constructed at the Naval Research Laboratory. The data obtained using the CITRIS instrument will provide a global description of the ionosphere from orbits with inclinations ranging from 15 degrees to 70 degrees and altitudes from 375 to 800 km. The tandem operations of the CITRIS and CERTO instruments will provide the fully low-earth-orbit based occultation measurements of the ionosphere. All of the data will be available for rapid assimilation

  8. SCINTILLATION SPECTROMETER

    DOEpatents

    Bell, P.R.; Francis, J.E.

    1960-06-21

    A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

  9. 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.

  10. A Coincident Search for Radio and Gravitational Waves from Binary Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Cardena, Brett

    2011-05-01

    The merger of neutron star-neutron star binary pairs may be accompanied by the prompt emission of a coherent low-frequency radio pulse. This radio transient is produced as synchrotron radiation caused by the spin and rotation of the surface charge density of a pulsar through the magnetosphere of a larger neutron star, usually referred to as a Magnetar . This type of merger event would also result in the release of a gravitational coalescence wave-form. We will discuss a coincident radio transient and gravitational wave search. This search is being conducted by two radio telescope arrays: The Long Wave Array (LWA) and the Eight-meter-wavelength Transient Array (ETA) in coordination with the Laser Interferometer Gravitational-Wave Observatory (LIGO). We will outline this ongoing coincident search and discuss some preliminary results.

  11. 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)

  12. Energetic electrons and plasma waves associated with a solar type III radio burst

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Potter, D. W.; Gurnett, D. A.; Scarf, F. L.

    1981-01-01

    Detailed in situ observations from the ISEE 3 spacecraft of energetic electrons, plasma waves, and radio emission for the type II solar radio burst of February 17, 1979, are presented. The reduced, one-dimensional electron distribution function is constructed as a function of time. Since the faster electrons arrive before the slower ones, a bump on tail distribution forms which is unstable to the growth of Langmuir waves. The plasma wave growth computed from the distribution function agrees well with the observed onset of the Langmuir waves, and there is qualitative agreement between variations in the plasma wave levels and in the development of regions of positive slope in the function. The evolution of the function, however, predicts far higher plasma wave levels than those observed. The maximum levels observed are approximately equal to the threshold for nonlinear wave processes, such as oscillation two-stream instability and soliton collapse.

  13. Wave Normal and Poynting Vector Calculations using the Cassini Radio and Plasma Wave Instrument

    NASA Technical Reports Server (NTRS)

    Hospodarsky, G. B.; Averkamp, T. F.; Kurth, W. S.; Gurnett, D. A.; Dougherty, M.; Inan, Umran; Wood, Troy

    2001-01-01

    Wave normal and Poynting vector measurements from the Cassini radio and plasma wave instrument (RPWS) are used to examine the propagation characteristics of various plasma waves during the Earth flyby on August 18, 1999. Using the five-channel waveform receiver (WFR), the wave normal vector is determined using the Means method for a lightning-induced whistler, equatorial chorus, and a series of low-frequency emissions observed while Cassini was in the magnetosheath. The Poynting vector for these emissions is also calculated from the five components measured by the WFR. The propagation characteristics of the lightning-induced whistler were found to be consistent with the whistler wave mode of propagation, with propagation antiparallel to the magnetic field (southward) at Cassini. The sferic associated with this whistler was observed by both Cassini and the Stanford VLF group at the Palmer Station in Antarctica. Analysis of the arrival direction of the sferic at the Palmer Station suggests that the lightning stroke is in the same sector as Cassini. Chorus was observed very close (within a few degrees) to the magnetic equator during the flyby. The chorus was found to propagate primarily away from the magnetic equator and was observed to change direction as Cassini crossed the magnetic equator. This suggests that the source region of the chorus is very near the magnetic equator. The low-frequency emission in the magnetosheath has many of the characteristics of lion roars. The average value of the angle between the wave normal vector and the local magnetic field was found to be 16 degrees, and the emissions ranged in frequency from 0. 19 to 0.75 f(sub ce), where f(sub ce) is the electron cyclotron frequency. The wave normal vectors of these waves were primarily in one direction for each individual burst (either parallel or antiparallel to the local field) but varied in direction throughout the magnetosheath. This suggests that the sources of the emissions are far from

  14. An analysis of bending waves in Saturn's rings using Voyager radio occultation data

    NASA Technical Reports Server (NTRS)

    Gresh, Donna L.; Rosen, Paul A.; Tyler, G. Leonard; Lissauer, Jack J.

    1986-01-01

    Three oscillatory features in the Voyager 1 radio occultation map of Saturn's rings have been identified as the 5:3, 7:4, and 4:2 spiral bending waves excited by the satellite Mimas. The observations are presented and the wave properties are investigated. It is found that the Mimas 7:4 wave is consistent with the linear theory of bending waves, while the Mimas 5:3 wave may not be. A detailed analysis of the Mimas 4:2 bending wave was not possible due to the large optical depth in the region in which it propagates.

  15. 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)

  16. 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

  17. Approach warning system for snowplow using aerial-high-power ultrasonic wave with radio wave

    NASA Astrophysics Data System (ADS)

    Manabu, Aoyagi; Yuta, Amagi; Hiroaki, Miura; Okeya, Ryota; Hideki, Tamura; Takehiro, Takano

    2012-05-01

    An approach warning system for a snowplow and guide was developed by using aerial-high-power ultrasonic transducer. To be robust against some serious factors in winter, ultrasonic signal and radio one were combined on the system, and the flat face side of stepped circular vibrating plate was utilized as a radiation plate. The ultrasonic wave radiated from the flat face side still had a better directivity, and the flat face had advantage to prevent bad influences from water, snow or ice. From experiment results, when double transducers were set on both sides of roof of snowplow, this system was able to be measure distance between a guide and snowplow in whole of controlled area.

  18. 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.

  19. 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.

  20. Cassini radio and plasma wave investigation: Data compression and scientific applications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The Radio and Plasma Wave Science (RPWS) experiment being built for the Cassini spacecraft will study a wide range of plasma and radio wave phenomena in the magnetosphere of Saturn and will also make valuable measurements during the cruise phase and at other encounters. A feature of data from wave receivers is the capability of producing vastly more data than the spacecraft telemetry link is capable of transmitting back to the Earth. Thus, techniques of on-board data compression and data reduction are important. The RPWS instrument has one processor dedicated to data compression tasks.

  1. Cassini radio and plasma wave investigation - Data compression and scientific applications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The Radio and Plasma Wave Science (RPWS) experiment being built for the Cassini spacecraft will study a wide range of plasma and radio wave phenomena in the magnetosphere of Saturn and will also make valuable measurements during the cruise phase and at other encounters. A feature of data from wave receivers is the capability of producing vastly more data than the spacecraft telemetry link is capable of transmitting back to the Earth. Thus, techniques of on-board data compression and data reduction are important. The RPWS instrument has one processor dedicated to data compression tasks.

  2. Commensal searches for microhertz gravitational waves and fast radio bursts: A pilot study

    NASA Astrophysics Data System (ADS)

    Shannon, Ryan; Hobbs, George; Ravi, Vikram

    2014-04-01

    In this pilot observing programme, we propose to observe at high cadence the transient gravitational-wave and radio-wave Universe. The goals of these observations are threefold: 1) To improve the timing precision of secondary pulsars in the Parkes Pulsar Timing Array (PPTA) to accelerate the detection of gravitational waves; 2) To characterise the gravitational wave universe in the hitherto unexplored microhertz frequency band; and 3) To develop methods and search for fast radio bursts (FRBs) while conducting precision time experiments. To achieve these goals, we request 120 hours of observations with the Parkes multibeam system, divided into 10 epochs comprising 12-hour LST days. This pilot project acts as a feasibility study for modifications to both the PPTA project and the International Pulsar Timing Array (IPTA), the consortium coordinating timing array observations in Australia, Europe, and North America, and assess the feasibility of searching for fast radio bursts while conduction precision timing observations.

  3. Turbulence-induced scintillation on Gaussian-beam waves: theoretical predictions and observations from a laser-illuminated satellite

    NASA Astrophysics Data System (ADS)

    Shelton, John D.

    1995-10-01

    Expressions for the variance and the power spectral density of turbulence-induced log-amplitude fluctuations are derived for Gaussian-beam waves in the regime of weak scattering. This formulation includes effects that are due to turbulence strength variations along the propagation path, offset of the observation point from the beam axis, and sensitivity to focus and beam diameter. Comparison of theoretical results with observed scintillation during experiments with a laser-illuminated satellite reveals good agreement. Copyright (c) 1995 Optical Society of America

  4. 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.

  5. 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.

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

    SciTech Connect

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

    2015-10-15

    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.

  7. 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.

  8. 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.

  9. 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.

  10. Influence of short gravity waves on thermal radio emission of water surface

    NASA Astrophysics Data System (ADS)

    Ilin, V. A.; Naumov, A. A.; Rayzer, V. Y.; Filonovich, S. R.; Etkin, V. S.

    1985-06-01

    An experimental study is presented of the thermal radio emission caused by short waves, accompanied by a quantitative interpretation of the data obtained. Emphasis is on an analysis of the variation in radio brightness contrast as a function of steepness of the short gravity waves, measured by means of a high-frequency radiometer operating in the lambda = 0.8 cm range. Waves were artificially generated in a small channel, wavelength 8 to 40 cm, height 0.6 to 3 cm. Due to the high sensitivity of the radiometric apparatus used, effects were recorded which were related to the influence of the profile and steepness of the short gravity waves. The possibility of using the geometrical optics approximation for quantitative interpretation of the experimental data is demonstrated. The model is based on essentially non-Gaussian statistics of slopes corresponding to quasimonochromatic waves of finite amplitude.

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

    SciTech Connect

    Maski, Kalpana; Vijay, S. K.

    2015-07-31

    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.

  12. 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.

  13. 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.

  14. 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

  15. Application of surface acoustic wave devices to radio telemetry

    NASA Technical Reports Server (NTRS)

    Strasilla, U.

    1983-01-01

    Three experimental Surface Acoustic Wave Resonators (SAWR) are developed and evaluated. A desired center frequency is obtained by correct spacing of the Inter-Digital Transducers (IDT). Transmitting and receiving IDT's must be close for adequate coupling and a sufficient number of reflectors are required to create a high quality standing wave. A review of oscillator theory is given and current technology evaluated.

  16. Estimation of Electron Density profile Using the Propagation Characteristics of Radio Waves by S-520-29 Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Itaya, K.; Ishisaka, K.; Ashihara, Y.; Abe, T.; Kumamoto, A.; Kurihara, J.

    2015-12-01

    S-520-29 sounding rocket experiment was carried out at Uchinoura Space Center (USC) at 19:10 JST on 17 August, 2014. The purpose of this sounding rocket experiments is observation of sporadic E layer that appears in the lower ionosphere at near 100km. Three methods were used in order to observe the sporadic E layer. The first method is an optical method that observe the light of metal ion emitted by the resonance scattering in sporadic E layer using the imager. The second method is observation of characteristic of radio wave propagation that the LF/MF band radio waves transmitted from the ground. The third method is measuring the electron density in the vicinity of sounding rocket using the fast Langmuir probe and the impedance probe. We analyze the propagation characteristics of radio wave in sporadic E layer appeared from the results of the second method observation. This rocket was equipped with LF/MF band radio receiver for observe the LF/MF band radio waves in rocket flight. Antenna of LF/MF band radio receiver is composed of three axis loop antenna. LF/MF band radio receiver receives three radio waves of 873kHz (JOGB), 666kHz (JOBK), 60kHz (JJY) from the ground. 873kHz and 60kHz radio waves are transmitting from north side, and 666kHz radio waves are transmitting from the east side to the trajectory of the rocket. In the sounding rocket experiment, LF/MF band radio receiver was working properly. We have completed the observation of radio wave intensity. We analyze the observation results using a Doppler shift calculations by frequency analysis. Radio waves received by the sounding rocket include the influences of Doppler shift by polarization and the direction of rocket spin and the magnetic field of the Earth. So received radio waves that are separate into characteristics waves using frequency analysis. Then we calculate the Doppler shift from the separated data. As a result, 873kHz, 666kHz radio waves are reflected by the ionosphere. 60kHz wave was able to

  17. Propagation characteristics of the ionospheric transmission window relating to long wave radio location issues

    NASA Astrophysics Data System (ADS)

    Kossey, Paul A.; Lewis, Edward A.

    1992-11-01

    Most applications of long radio waves (ELF/VLF/LF/MF) are ground-based and exploit the fact that such signals can propagate to great distances via reflections from the lower ionosphere. It is known however that, owing to the influence of the earth's magnetic field, long wave signals can penetrate through the ionosphere as well; at times, the waves penetrate with relatively little loss, depending on ionospheric conditions and other propagation factors. This has prompted investigations of the long wave 'ionospheric transmission window' as part of efforts to assess the feasibility of deploying long wave emitters in space for terrestrial applications and/or for exploiting, in space, signals emanating from ground-based long wave transmitters. This paper outlines results of theoretical and experimental investigations of the ionospheric transmission window over the frequency range from about 100 Hz to 500 kHz, with emphasis on directional issues associated with long wave penetration of the ionosphere.

  18. 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.

  19. 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

  20. 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

  1. Results of refraction-angle measurement of radio waves in the Venus atmosphere on the basis of bistatic radar data

    NASA Astrophysics Data System (ADS)

    Salimzyanov, R. R.; Pavel'Ev, D. A.

    1993-08-01

    Improved measurements of refraction in the Venus atmosphere using bistatic radar data have been obtained. To describe the refraction effects, a theoretical model is developed that makes it possible to determine the parameters for calculating radio communication lines in the Venus troposphere from the height dependence of the refractive index. Expressions are obtained relating the phase path length of radio waves and the integral absorption of radio waves in the atmosphere to the parameters of the theoretical model.

  2. Forecasting characteristics of propagation of decameter radio waves using the global ionosphere and plasmasphere model

    NASA Astrophysics Data System (ADS)

    Ponomarchuk, Sergey; Kotovich, Galina; Romanova, Elena; Tashchilin, Anatoliy

    2015-09-01

    We present the results of forecasting maximum usable frequencies (MUF) on middle-latitude paths on the basis of complex algorithm including modules of the ionosphere and plasmasphere global model (IPGM) and the model of radio wave propagation. The computation of propagation characteristics for decameter radio waves is carried out within the framework of normal wave technique. IPGM developed in ISTP SB RAS enables to compute electron concentration profiles and effective frequency of collisions using minimum number of input data and taking into account physical processes in the Earth's upper atmosphere. To estimate the efficiency of using IPGM in long-term forecast of radio wave propagation we computed MUF for radio communication in various heliogeophysical conditions. To obtain precision characteristics of MUF forecast we used experimental data of oblique sounding on Magadan-Irkutsk, Khabarovsk-Irkutsk, Norilsk-Irkutsk paths. The paths are equipped with modern ionosphere diagnostic hardware for oblique sounding by continuous chirp signal. We also compared results of MUF forecast using IPGM with computations carried out according IRI model.

  3. Dust Detection Using Radio and Plasma Wave Instruments in the Solar System

    NASA Astrophysics Data System (ADS)

    Ye, S.; Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F.; Kempf, S.; Hsu, S.; Srama, R.; Grün, E.; Morooka, M. W.; Sakai, S.; Wahlund, J. E.

    2014-12-01

    Nanometer to micrometer sized dust particles pervade our solar system. The origins of these dust particles include asteroid collisions, cometary activity, and geothermal activity of the planetary moons, for example, the water dust cloud ejected from Saturn's moon Enceladus. Radio and plasma wave instruments have been used to detect such dust particles via voltage pulses induced by impacts on the spacecraft body and antennas. The first detection of such dust impacts occurred when Voyager 1 passed through Saturn's ring plane. Since then, dust impacts have been detected by radio and plasma wave instruments on many spacecraft, including ISEE-3, Cassini, and STEREO. In this presentation, we review the detection of dust particles in the solar system using radio and plasma wave instruments aboard various spacecraft since the Voyager era. We also show characteristics of the dust particles derived from recent observations by Cassini RPWS in Saturn's magnetosphere. The dust size distribution and density are consistent with those measured by the conventional dust detectors. A new method of measuring the electron density inside the Enceladus plume based on plasma oscillations observed after dust impacts will also be discussed. The dust measurement by radio and plasma wave instruments complements that by conventional dust detectors and provide important information about the spatial distribution of dust particles due to less pointing constraints and the larger detection area.

  4. 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.)

  5. 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.

  6. 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.

  7. Radio and plasma wave observations at Saturn from Cassini's approach and first orbit.

    PubMed

    Gurnett, D A; Kurth, W S; Hospodarsky, G B; Persoon, A M; Averkamp, T F; Cecconi, B; Lecacheux, A; Zarka, P; Canu, P; Cornilleau-Wehrlin, N; Galopeau, P; Roux, A; Harvey, C; Louarn, P; Bostrom, R; Gustafsson, G; Wahlund, J-E; Desch, M D; Farrell, W M; Kaiser, M L; Goetz, K; Kellogg, P J; Fischer, G; Ladreiter, H-P; Rucker, H; Alleyne, H; Pedersen, A

    2005-02-25

    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 +/- 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. PMID:15604362

  8. 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.

  9. Design, fabrication, and measurement of reflective metasurface for orbital angular momentum vortex wave in radio frequency domain

    NASA Astrophysics Data System (ADS)

    Yu, Shixing; Li, Long; Shi, Guangming; Zhu, Cheng; Zhou, Xiaoxiao; Shi, Yan

    2016-03-01

    In this paper, a reflective metasurface is designed, fabricated, and experimentally demonstrated to generate an orbital angular momentum (OAM) vortex wave in radio frequency domain. Theoretical formula of phase-shift distribution is deduced and used to design the metasurface producing vortex radio waves. The prototype of a practical configuration is designed, fabricated, and measured to validate the theoretical analysis at 5.8 GHz. The simulated and experimental results verify that the vortex waves with different OAM mode numbers can be flexibly generated by using sub-wavelength reflective metasurfaces. The proposed method and metasurface pave a way to generate the OAM vortex waves for radio and microwave wireless communication applications.

  10. 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

  11. Radio frequency wave experiments on the MST reversed field pinch

    SciTech Connect

    Forest, C. B.; Chattopadhyay, P. K.; Nornberg, M. D.; Prager, S. C.; Thomas, M. A.; Uchimoto, E.; Smirnov, A. P.; Harvey, R. W.; Ram, A. K.

    1999-09-20

    Whether there is a self-consistent path from poor confinement to greatly improved confinement through current profile modification is an issue for future experiments to address if and only if near term experiments can demonstrate: (1) coupling to and the propagation of rf waves in RFP plasmas, (2) efficient current drive, and (3) control of the power deposition which will make it possible to control the current profile. In this paper, modeling results and experimental plans are presented for two rf experiments which have the potential of satisfying these three goals: high-n{sub (parallel} {sub sign)} lower hybrid (LH) waves and electron Bernstein waves (EBWs). (c) 1999 American Institute of Physics.

  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. 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.

  14. 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.

  15. 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.

  16. Mapping Natural and Man-made Radio Interference at the Moon: Wind Waves RAD2 Data

    NASA Astrophysics Data System (ADS)

    MacDowall, R. J.; Hess, R. A.; Kaiser, M. L.; Farrell, W. M.

    2009-12-01

    The lunar surface is frequently identified as a preferred site for large, low-frequency (<50-100 MHz) interferometric radio observatories. Compared to ground-based facilities limited to above 10 MHz by ionospheric absorption, the Moon has essentially no ionosphere. Observations of radio sources at frequencies below 100 kHz would be possible. Compared to a free-flying spacecraft constellation, the lunar surface provides a surface for deploying antennas, after which the antenna metrology is not an issue. Also compared to the spacecraft constellation, the moon offers a “backstop” that can block unwanted radio emissions from the sun or, for a far-side array, from man-made transmitters on Earth as well as terrestrial auroral radio emissions. We present an analysis of the Wind Waves RAD2 radio data set for the frequency range 1-14 MHz. These data, acquired from November 1994 through the present, document the radio bursts and terrestrial emissions observed by Wind along a complex trajectory that included passes very close to the Moon. Thus, we can build a statistical “map” of terrestrial radio emissions as a function of local time of the Moon relative to earth, the inclination of the moon’s orbit, and frequency. These data demonstrate that successful radio observations of cosmological sources from anywhere near Earth will be best accomplished by an observatory on the far-side of the Moon. The data also provide statistics regarding interference from solar radio emissions, including variations as a function of the solar cycle, with any observations requiring high sensitivity.

  17. 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.

  18. 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.

  19. Radio frequency wave experiments on the MST reversed field pinch

    SciTech Connect

    Forest, C.B.; Chattopadhyay, P.K.; Nornberg, M.D.; Prager, S.C.; Thomas, M.A.; Uchimoto, E.; Smirnov, A.P.; Harvey, R.W.; Ram, A.K.

    1999-04-01

    Experiments, simulations, and theory all indicate that the magnetic fluctuations responsible for the poor confinement in the reversed field pinch (RFP) can be controlled by altering the radial profile of the current density. The magnetic fluctuations in the RFP are due to resistive MHD instabilities caused by current profile peaking; thus confinement in the RFP is ultimately the result of a misalignment between inductively driven current profiles and the stable current profiles characteristic of the Taylor state. If a technique such as rf current drive can be developed to non-inductively sustain a Taylor state (a current profile linearly stable to all tearing modes), the confinement of the RFP and its potential as a reactor concept are likely to increase. Whether there is a self-consistent path from poor confinement to greatly improved confinement through current profile modification is an issue for future experiments to address if and only if near term experiments can demonstrate: (1) coupling to and the propagation of rf waves in RFP plasmas, (2) efficient current drive, and (3) control of the power deposition which will make it possible to control the current profile. In this paper, modeling results and experimental plans are presented for two rf experiments which have the potential of satisfying these three goals: high-n{sub {parallel}} lower hybrid (LH) waves and electron Bernstein waves (EBWs).

  20. 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.

  1. 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.

  2. Evaluation of Coronal Shock Wave Velocities from the II Type Radio Bursts Parameters

    NASA Astrophysics Data System (ADS)

    Galanin, V. V.; Isaeva, E. A.; Kravetz, R. O.

    The work presents the results of research of connection between the coronal shock waves and the parameters of type II (mII) meter-decameter bursts in 25-180 MHz band for 66 solar proton events. The velocities of coronal shock waves for this two cases where determined. In the first case the velocities of the shock waves was evaluated according to the Newkirck model and in the second case - directly from the type II radio burst parameters. The calculated values of shock waves velocity was compared with the same velocity values that is published on NGDC site. The comparative analysis showed that precision of coronal shock waves velocity estimation which gets directly from type II radio bursts parameters was higher than the same one which used the Newkirck model. Research showed that there is exist the sufficiently strong connection between the shock wave velocity and the delay of type II burst intensity maximum on the second harmonica. Correlation coefficient between the studied parameters was equal to ≍ 0.65.

  3. 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…

  4. Generation and Upper Atmospheric Propagation of Acoustic Gravity Waves according to Numerical Modeling and Radio Tomography

    NASA Astrophysics Data System (ADS)

    Vorontsov, Artem; Andreeva, Elena; Nesterov, Ivan; Padokhin, Artem; Kurbatov, Grigory

    2016-04-01

    The acoustic-gravity waves (AGW) in the upper atmosphere and ionosphere can be generated by a variety of the phenomena in the near-Earth environment and atmosphere as well as by some perturbations of the Earth's ground or ocean surface. For instance, the role of the AGW sources can be played by the earthquakes, explosions, thermal heating, seisches, tsunami waves. We present the examples of AGWs excited by the tsunami waves traveling in the ocean, by seisches, and by ionospheric heating by the high-power radio wave. In the last case, the gravity waves are caused by the pulsed modulation of the heating wave. The AGW propagation in the upper atmosphere induces the variations and irregularities in the electron density distribution of the ionosphere, whose structure can be efficiently reconstructed by the method of the ionospheric radio tomography (RT) based on the data from the global navigational satellite systems (GNSS). The input data for RT diagnostics are composed of the 150/400 MHz radio signals from the low-orbiting (LO) satellites and 1.2-1.5 GHz radio signals from the high-orbiting (HO) satellites with their orbits at ~1000 and ~20000 km above the ground, respectively. These data enable ionospheric imaging on different spatiotemporal scales with different spatiotemporal resolution and coverage, which is suitable, inter alia, for tracking the waves and wave-like features in the ionosphere. In particular, we demonstrate the maps of the ionospheric responses to the tornado at Moore (Oklahoma, USA) of May 20, 2013, which are reconstructed from the HO data. We present the examples of LORT images containing the waves and wavelike disturbances associated with various sources (e.g., auroral precipitation and high-power heating of the ionosphere). We also discuss the results of modeling the AGW generation by the surface and volumetric sources. The millihertz AGW from these sources initiate the ionospheric perturbation with a typical scale of a few hundred km at the

  5. An investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation

    NASA Astrophysics Data System (ADS)

    Secan, James A.; Bussey, Robert M.; Fremouw, Edward J.; Reinleitner, Lee A.

    1993-03-01

    Many modern military systems used for communications, command and control, navigation, and surveillance depend on reliable and relatively noise-free transmission of radiowave signals through the earth's ionosphere. Small-scale irregularities in the ionospheric density can cause severe distortion, known as radiowave scintillation, of both the amplitude and phase of these signals. The WBMOD computer program can be used to estimate these effects on a wide range of systems. The objective of this study is to investigate improvements to the WBMOD model based on extensive data sets covering both the equatorial and high-latitude regimes. This report summarizes the work completed during the first year, which includes construction of the modeling database, development of a new format for the internal representation of the irregularity strength, and development of new models for the diurnal, latitudinal, seasonal, and longitudinal variations in the equatorial region.

  6. Investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation. Technical report

    SciTech Connect

    Secan, J.A.; Bussey, R.M.

    1993-11-01

    Many modern military systems used for communications, command and control, navigation, and surveillance depend on reliable and relatively noise-free transmission of radiowave signals through the earth's ionosphere. Small-scale irregularities in the ionospheric density can cause severe distortion, known as radiowave scintillation, of both the amplitude and phase of these signals. The WBMOD computer program can be used to estimate these effects on a wide range of systems. The objective of this study is to investigate improvements to the WBMOD model based on extensive data sets covering both the equatorial and high-latitude regimes. This report summarizes the work completed during the second year, which include completion of the new models for the equatorial region and initial development of models for the high latitude (auroral and polar cap) region.

  7. Auto- and cross-correlation analysis of the QSOs radio wave intensity

    NASA Astrophysics Data System (ADS)

    Demin, S. A.; Panischev, O. Yu; Nefedyev, Yu A.

    2015-12-01

    We discuss here the Flicker-Noise Spectroscopy approach to studying astrophysical systems, for example the radio wave intensity of quasi-stellar object (QSO) 1641+399 and BL Lacertae (BL Lac) 0215+015 in different frequency ranges. The presented method allows to parameterize the study dynamics using a short set of characteristics. The considering sources have a significant differences in manifesting the non-stationary effects, dynamical intermittency and synchronization. The radio wave intensity dynamics of the BL Lac 0215+015 is characterized by well-defined set of natural frequencies, persistent behavior with low effects of non-stationarity and high level of frequency-phase synchronization. For dynamics of the QSO 1641+399 reverse occurs including the asymmetrical structure of cross-correlator. Our findings show that using the flicker-noise spectroscopy approach to studying astrophysical objects allows to carry out the more detail analysis of their behavior and evolution.

  8. Gravitational-wave Constraints on the Progenitors of Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Callister, Thomas; Kanner, Jonah; Weinstein, Alan

    2016-07-01

    The nature of fast radio bursts (FRBs) remains enigmatic. Highly energetic radio pulses of millisecond duration, FRBs are observed with dispersion measures consistent with an extragalactic source. A variety of models have been proposed to explain their origin. One popular class of theorized FRB progenitor is the coalescence of compact binaries composed of neutron stars and/or black holes. Such coalescence events are strong gravitational-wave emitters. We demonstrate that measurements made by the LIGO and Virgo gravitational-wave observatories can be leveraged to severely constrain the validity of FRB binary coalescence models. Existing measurements constrain the binary black hole rate to approximately 5% of the FRB rate, and results from Advanced LIGO’s O1 and O2 observing runs may place similarly strong constraints on the fraction of FRBs due to binary neutron star and neutron star–black hole progenitors.

  9. 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.

  10. Detectable radio flares following gravitational waves from mergers of binary neutron stars.

    PubMed

    Nakar, Ehud; Piran, Tsvi

    2011-10-01

    Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled. PMID:21964342

  11. 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

  12. On the determination of gravity wave momentum flux from GPS radio occultation data

    NASA Astrophysics Data System (ADS)

    Faber, A.; Llamedo, P.; Schmidt, T.; de la Torre, A.; Wickert, J.

    2013-11-01

    Global Positioning System (GPS) radio occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received by low Earth-orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions, offering the possibility of global monitoring of the vertical temperature structure and atmospheric wave parameters. The six-satellite constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. Here, a method for the determination of the real horizontal wavelength from three vertical profiles is applied to the COSMIC data. The horizontal and vertical wavelength, the specific potential energy (Ep), and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  13. Experimental comparison between centimeter- and millimeter-wave ultrawideband radio channels

    NASA Astrophysics Data System (ADS)

    Martinez-Ingles, Maria-Teresa; Molina-Garcia-Pardo, Jose-Maria; Rodríguez, José-Víctor; Pascual-García, Juan; Juan-Llácer, Leandro

    2014-06-01

    This paper analyzes radio wave propagation phenomena at two very different frequency bands: 2-10 GHz (centimeter wave) and 57-66 GHz (millimeter wave (mm-W)). The two frequency bands have been measured using the same equipment and under similar propagation conditions, such as path loss, root-mean-square delay spread, maximum excess delay, and Rician K factor, and their respective correlations compared. Obstructed line of sight situations have also been considered by using metal and cardboard obstructions. The statistical distributions, main specular reflections, and decay factors have been found similar for the two bands. However, the measured path loss, correlation in terms of electrical distances, and the K factor are higher for the millimeter-wave frequency band. Indeed, the importance of propagation mechanism changes from one band to the other, which must be considered in the design of future mm-W systems.

  14. 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.

  15. Radio wave refraction caused by artificial disturbances of the ionosphere - A numerical experiment

    NASA Astrophysics Data System (ADS)

    Ivanov, V. B.; Svistunov, K. V.

    The method of trajectory calculations is used to study short-wave propagation in the ionosphere, in the presence of large-scale inhomogeneities, due to plasma heating by means of high-power transmissions. It is shown that the refraction caused by the artificial disturbances can result in variations of the radio path distances, the occurrence of ricochet trajectories, and the focusing and defocusing of the radiation.

  16. High performance superconducting radio frequency ingot niobium technology for continuous wave applications

    SciTech Connect

    Dhakal, Pashupati Ciovati, Gianluigi Myneni, Ganapati R.

    2015-12-04

    Future continuous wave (CW) accelerators require the superconducting radio frequency cavities with high quality factor and medium accelerating gradients (≤20 MV/m). Ingot niobium cavities with medium purity fulfill the specifications of both accelerating gradient and high quality factor with simple processing techniques and potential reduction in cost. This contribution reviews the current superconducting radiofrequency research and development and outlines the potential benefits of using ingot niobium technology for CW applications.

  17. 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.

  18. Focus Adjustment System of Laser Probe for Radio Frequency Surface and Bulk Acoustic Wave Devices

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Kashiwa, Keisuke; Hashimoto, Ken-ya; Omori, Tatsuya; Yamaguchi, Masatsune; Kasai, Naoki

    2009-10-01

    In this paper, we describe a focus adjustment system designed especially for a fast-mechanical-scanning laser probe for radio-frequency surface and bulk acoustic wave devices. When high spatial resolution is necessary for the observation, one needs an objective lens of large magnifying power with extremely shallow focal depth. Then, a small inclination of a measurement device may cause severe defocus resulting in blurred images. We installed the focus adjustment system in the laser probe, and showed that even with inclination, high-quality information of the wave field can be acquired without reducing the scanning speed.

  19. Search for non-thermal radio emission from Eta Carina's outer blast wave with ATCA

    NASA Astrophysics Data System (ADS)

    Ohm, Stefan; Urquhart, James; Skilton, Joanna Lucy; Hinton, Jim; Domainko, Wilfried

    2010-10-01

    Non-thermal hard X-ray and high-energy (HE; 1 MeV < E < 100 GeV) gamma-ray emission in the direction of Eta Carina has been recently detected using the INTEGRAL, AGILE and Fermi satellites. This emission can be either interpreted in the framework of particle acceleration in the colliding wind region between the two massive stars or in the very fast moving blast wave which originates in the historical 1843 "Great Eruption". The detection of a radio shell at the location of the shock would support the latter scenario and confirm Eta Carina as prime example of a new source type, namely, an LBV star whose massive ejecta accelerates electrons to non-thermal energies. While Fermi and INTEGRAL do not provide sufficient angular resolution to resolve the blast wave, high resolution radio observations using ATCA will be able to test non-thermal radio emission from this acceleration site. The current sensitivity of ATCA is such that a relatively modest observation time of 12 hours will be sufficient to image the synchrotron emission from the blast region down to magnetic field strengths well below typical ISM values and hence prove or reject our blast-wave hypothesis for the high energy emission.

  20. Influence of tropical F region in ionosphere on propagation of short radio waves

    NASA Astrophysics Data System (ADS)

    Kolomiytsev, O. P.; Savchenko, P. P.

    1985-05-01

    Tropical ionospheric waveguides in the presence of stratification of the electron concentration maximum were studied. Under these conditions a specific form of vertical electron concentration profile is formed which to a great extent determines the nature and conditions of propagation of short radio waves in the low latitudes. The phase trajectories were computed for a spherically stratified ionosphere. Three approaches for description of the ionospheric waveguide were used: comparative, temporal, latitudinal. Examples of computations are given which show that in a wide spatial-temporal range in the tropical ionosphere there is an additional ionospheric waveguide in which radio waves can be propagated along ricochetting trajectories. At identical time there can be three types of phases trajectories or three types of adjacent channels, each of which is characterized by a definite working frequency and definite conditions for the propagation of radio waves in it. The computations presented give a qualitative representation of the influence of stratification of the electron concentration on the formation, dynamics and degeneration of the additional ionospheric waveguides in the tropical latitudes.

  1. Fokker-Planck description of the scattering of radio frequency waves at the plasma edge

    SciTech Connect

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

    2010-02-15

    In magnetic fusion devices, radio frequency (rf) waves in the electron cyclotron (EC) and lower hybrid (LH) range of frequencies are being commonly used to modify the plasma current profile. In ITER, EC waves are expected to stabilize the neoclassical tearing mode (NTM) by providing current in the island region [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)]. The appearance of NTMs severely limits the plasma pressure and leads to the degradation of plasma confinement. LH waves could be used in ITER to modify the current profile closer to the edge of the plasma. These rf waves propagate from the excitation structures to the core of the plasma through an edge region, which is characterized by turbulence--in particular, density fluctuations. These fluctuations, in the form of blobs, can modify the propagation properties of the waves by refraction. In this paper, the effect on rf due to randomly distributed blobs in the edge region is studied. The waves are represented as geometric optics rays and the refractive scattering from a distribution of blobs is formulated as a Fokker-Planck equation. The scattering can have two diffusive effects--one in real space and the other in wave vector space. The scattering can modify the trajectory of rays into the plasma and it can affect the wave vector spectrum. The refraction of EC waves, for example, could make them miss the intended target region where the NTMs occur. The broadening of the wave vector spectrum could broaden the wave generated current profile. The Fokker-Planck formalism for diffusion in real space and wave vector space is used to study the effect of density blobs on EC and LH waves in an ITER type of plasma environment. For EC waves the refractive effects become important since the distance of propagation from the edge to the core in ITER is of the order of a meter. The diffusion in wave vector space is small. For LH waves the refractive effects are insignificant but the diffusion in wave vector space is

  2. An estimation of the LF-MF high latitude communication radio lines range on surface electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Bashkuev, Yu. B.; Dembelov, M. G.; Angarkhaeva, L. Kh.; Naguslaeva, I. B.; Khaptanov, V. B.; Buyanova, D. G.

    2015-11-01

    The paper is devoted to estimation of the LF-MF high latitude communication radio lines range on surface electromagnetic waves (SEW). A surface impedance of sea areas of water in summer and winter time is considered. An example of calculations of the ground wave field over inhomogeneous impedance paths including stratified inhomogeneous structure "ice-sea" is given. It is shown that due to the emergence of SEW the Arctic radio lines range increases significantly.

  3. 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.

  4. Frequency correlation of probe waves backscattered from small scale ionospheric irregularities generated by high power HF radio waves

    NASA Astrophysics Data System (ADS)

    Puchkov, V. A.

    2016-09-01

    Aspect sensitive scattering of multi-frequency probe signals by artificial, magnetic field aligned density irregularities (with transverse size ∼ 1- 10 m) generated in the ionosphere by powerful radio waves is considered. Fluctuations of received signals depending on stochastic properties of the irregularities are calculated. It is shown that in the case of HF probe waves two mechanisms may contribute to the scattered signal fluctuations. The first one is due to the propagation of probe waves in the ionospheric plasma as in a randomly inhomogeneous medium. The second one lies in non-stationary stochastic behavior of irregularities which satisfy the Bragg conditions for the scattering geometry and therefore constitute centers of scattering. In the probe wave frequency band of the order of 10-100 MHz the second mechanism dominates which delivers opportunity to recover some properties of artificial irregularities from received signals. Correlation function of backscattered probe waves with close frequencies is calculated, and it is shown that detailed spatial distribution of irregularities along the scattering vector can be found experimentally from observations of this correlation function.

  5. 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.

  6. Estimated errors in a global gravity wave climatology from GPS radio occultation temperature profiles

    NASA Astrophysics Data System (ADS)

    de la Torre, A.; Llamedo, P.; Alexander, P.; Schmidt, T.; Wickert, J.

    2010-07-01

    In a previous paper by Schmidt et al. (2008), from CHAllenging Minisatellite Payload (CHAMP) Global Positioning System (GPS) radio occultation data, a comparison was made between a Gaussian filter applied to the "complete" temperature profile and to its "separate" tropospheric and stratospheric height intervals, for gravity wave analyses. It was found that the separate filtering method considerably reduces a wave activity artificial enhancement near the tropopause, presumably due to the isolation process of the wave component. We now propose a simple approach to estimate the uncertainty in the calculation of the mean specific wave potential energy content, due exclusively to the filtering process of vertical temperature profiles, independently of the experimental origin of the data. The approach is developed through a statistical simulation, built up from the superposition of synthetic wave perturbations. These are adjusted by a recent gravity wave (GW) climatology and temperature profiles from reanalyses. A systematic overestimation of the mean specific wave potential energy content is detected and its variability with latitude, altitude, season and averaging height interval is highlighted.

  7. 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.

  8. 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.

  9. 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

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

    SciTech Connect

    Kuley, Animesh; Lin, Z.; 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.

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

    DOEpatents

    Ives, R. Lawrence; Mizuhara, Yosuke M.; Schumacher, Richard V.; Pendleton, Rand P.

    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.

  12. Long-term Measurements of Nighttime LF Radio Wave Reflection Heights over Central Europe

    NASA Astrophysics Data System (ADS)

    Jacobi, C.; Kürschner, D.

    2005-05-01

    The nighttime ionospheric absolute reflection height of low-frequency (LF) radio waves at oblique incidence has been measured continuously since late 1982 using 1.8kHz sideband phase comparisons between the sky wave and the ground wave of a commercial 177kHz LF transmitter. The dataset allows the analysis of long-term trends and other regular variations of the reflection height. Beside the clear signal of the 11-year solar cycle a quasi-biennial oscillation is visible in LF reflection heights, which is correlated to the equatorial stratospheric wind field. A long-term decreasing reflection height trend is found, confirming results from other measurements and theoretical estimations. The results can be interpreted as a long-term decrease of the height levels of fixed electron density in the lower E region, reflecting a long-term cooling trend of the middle atmosphere.

  13. 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.

  14. Full-wave reflection of lightning long-wave radio pulses from the ionospheric D- region

    NASA Astrophysics Data System (ADS)

    Jacobson, A. R.; Shao, X.; Holzworth, R.

    2008-12-01

    A model is developed for calculating ionospheric reflection of electromagnetic pulses emitted by lightning, with most energy in the long-wave spectral region (f = 3 - 100 kHz). The building-block of the calculation is a differential-equation full-wave solution of Maxwell's Equations for the complex reflection of individual plane waves incident from below, by the anisotropic, dissipative, diffuse dielectric profile of the lower ionosphere. This full-wave solution is then put into a summation over plane waves in an angular Direct Fourier Transform to obtain the reflection properties of curved wavefronts. This step models also the diffraction effects of long- wave ionospheric reflections observed at short or medium range (200 - 500 km). The calculation can be done with any arbitrary but smooth dielectric profile versus altitude. For an initial test, we use the classic D- region exponential profiles of electron density and collision rate given by Wait. With even these simple profiles, our model of full-wave reflection of curved wavefronts captures some of the basic attributes of observed reflected waveforms recorded with the Los Alamos Sferic Array.

  15. Review of Ionospheric Scintillation Models and proposing a Novel Model for Characterizing High Latitude Irregularities

    NASA Astrophysics Data System (ADS)

    Deshpande, K.; Bust, G. S.; Clauer, C. R.

    2013-12-01

    The study of ionospheric scintillations of radio signal involves a problem of electromagnetic (EM) wave propagation in random media and has been a subject of interest for more than last 5 decades. Some of the representative works are by Booker et. al (1950), Ratcliffe (1956), Wernik and Liu (1975), Yeh and Liu (1982), Secan et. al (1995), Costa and Basu (2002), Rino and Carrano (2011). Many of the scintillation models employ a phase screen model introduced by Rino (1979). Beniguel and Hamel (2011) implemented a global ionospheric scintillation model for equatorial regions showing a good agreement of the model with measurements. Implementing these models in the study of ionospheric scintillations of radio signals at high latitudes could be challenging since the path of satellite signal to ground has a variable angle of incidence, in addition to the complicated geometry of magnetic field lines at high latitude and polar regions, and complex magnetosphere-ionosphere coupling mechanisms creating the irregularities. We have developed a high fidelity 3-dimensional Global Positioning System Ionospheric Scintillation Model (3D-GPSISM) which is a full 3D EM wave propagation model to simulate GPS scintillations in high latitude ionosphere. The results from this model can form a basic framework on the use of inverse method to understand the physics of high latitude irregularities using GPS scintillations. We are using our model and an inverse method for selected scintillation observations during 2010 - 2013 from GPS receivers at South Pole, McMurdo and remote stations on Antarctica in conjunction with ancillary observations from SuperDARN, magnetometers, All Sky Imagers etc. We believe that such inverse method can be used to derive certain characteristics of the irregularity causing the scintillations and further achieve an improved understanding of the physics of high latitude irregularities.

  16. Scintillation Monitoring Using Asymmetry Index

    NASA Astrophysics Data System (ADS)

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

    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.

  17. Involuntary human hand movements due to FM radio waves in a moving van.

    PubMed

    Huttunen, P; Savinainen, A; Hänninen, Osmo; Myllylä, R

    2011-06-01

    Finland TRACT Involuntary movements of hands in a moving van on a public road were studied to clarify the possible role of frequency modulated radio waves on driving. The signals were measured in a direct 2 km test segment of an international road during repeated drives to both directions. Test subjects (n=4) had an ability to sense radio frequency field intensity variations of the environment. They were sitting in a minivan with arm movement detectors in their hands. A potentiometer was used to register the hand movements to a computer which simultaneously collected data on the amplitude of the RF signal of the local FM tower 30 km distance at a frequency of about 100 MHz. Involuntary hand movements of the test subjects correlated with electromagnetic field, i.e. FM radio wave intensity measured. They reacted also on the place of a geomagnetic anomaly crossing the road, which was found on the basis of these recordings and confirmed by the public geological maps of the area.In conclusion, RF irradiation seems to affect the human hand reflexes of sensitive persons in a moving van along a normal public road which may have significance in traffic safety. PMID:21616774

  18. Peculiarities of long-wave radio bursts from solar flares preceding strong geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Prokudina, V. S.; Kuril'Chik, V. N.; Yermolaev, Yu. I.; Kudela, K.; Slivka, M.

    2009-02-01

    Radio bursts in the frequency range of 100-1500 kHz, recorded in 1997-2000 on the INTERBALL-1 satellite during the solar flares preceding the strong geomagnetic storms with D st < -100 nT, are analyzed in this paper. The observed long-wave III-type radio bursts of solar origin at frequencies of 1460 and 780 kHz were characterized by large values of the flux S f = 10-15 -10-17 W/m2 Hz and duration longer than 10 min. The rapid frequency drift of a modulated radio burst continued up to a frequency of 250 kHz, which testified that the exciting agent (a beam of energetic electrons) propagated from the Sun to the Earth. All such flares were characterized by the appearance of halo coronal mass ejections, observed by the LASCO/ SOHO, and by the presence of a southward Bz-component of the IMF, measured on the ACE and WIND spacecraft. In addition, shortly after radio bursts, the INTERBALL-1 satellite has recorded the fluxes of energetic electrons with E > 40 keV.

  19. Estimation of electron density profile in ionospheric D and lower E region by Rocket observation and Full wave analysis of LF and MF radio waves

    NASA Astrophysics Data System (ADS)

    Ashihara, Y.; Ishisaka, K.; Okada, T.; Miyake, T.; Murayama, Y.; Nagano, I.

    Electrons in ionospheric D region are closely related to neutral dynamic meteorology and chemistry including such as hydrated ion and NOx though the electron density is very small about ten -- several thousand cc Therefore it has the possibility to find a new physical knowledge in mesosphere and lower ionosphere Radio wave propagation characteristics in ionospheric D and lower E region are affected by an electron density profile As a inverse problem the electron density profile can be estimated by radio wave propagation characteristics measured by a sounding rocket S-310-33 sounding rocket was launched at Uchinoura Space Center USC at 0 30 a m LT on January 18 2004 We observed magnetic field intensities of two radio waves transmitted from Kanoya air base 238kHz and NHK Kumamoto 2nd ch 873kHz by using radio wave receivers onboarded the rocket Both of the magnetic field intensities were absorbed suddenly at 89km altitude The propagation characteristics in the ionosphere are calculated by using Full wave method It needs the electron density profile previously to calculate the propagation characteristics by Full wave method The electron density profile is estimated by according the radio wave propagation characteristics calculated by Full wave analysis with the observed one This estimation technique is called radio wave absorption method We found the thin ionospheric layer of about 1km at the altitude of 89km The electron density in this region is 2 6 times10 3 cc The electron density compared with one at 88km it was large number

  20. Scattering of radio frequency waves by cylindrical density filaments in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Ram, Abhay K.; Hizanidis, Kyriakos

    2016-02-01

    In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on the properties of RF waves has not been quantified experimentally, it is of interest to carry out a theoretical study to determine if fluctuations can affect the propagation characteristics of RF waves. Usually, the difference between the plasma density inside the filament and the background plasma density is sizable, the ratio of the density difference to the background density being of order one. Generally, this precludes the use of geometrical optics in determining the effect of fluctuations, since the relevant ratio has to be much less than one, typically, of the order of 10% or less. In this paper, a full-wave, analytical model is developed for the scattering of a RF plane wave by a cylindrical plasma filament. It is assumed that the plasma inside and outside the filament is cold and uniform and that the major axis of the filament is aligned along the toroidal magnetic field. The ratio of the density inside the filament to the density of the background plasma is not restricted. The theoretical framework applies to the scattering of any cold plasma wave. In order to satisfy the boundary conditions at the interface between the filament and the background plasma, the electromagnetic fields inside and outside the filament need to have the same k∥ , the wave vector parallel to the ambient magnetic field, as the incident plane wave. Consequently, in contrast to the scattering of a RF wave by a spherical blob [Ram et al., Phys. Plasmas 20, 056110-1-056110-10 (2013)], the scattering by a field-aligned filament does not broaden the k∥ spectrum. However, the filament induces side-scattering leading to surface

  1. HF Radio Wave Propagation in the Ionosphere Observed with the ePOP RRI (Radio Receiver Instrument) -- SuperDARN Experiment

    NASA Astrophysics Data System (ADS)

    Hussey, G. C.; Gillies, R. G.; Ridley, C. G.; Yau, A. W.; McWilliams, K. A.; Sofko, G. J.

    2014-12-01

    The Radio Receiver Instrument (RRI) on the enhanced Polar Outflow Probe (ePOP) scientific payload of the recently launched CSA (Canadian Space Agency) CASSIOPE (Cascade Demonstrator Small-Sat and Ionospheric Polar Explorer) satellite mission and the Super Dual Auroral Radar Network (SuperDARN) of HF radars have successfully executed a number of experiments since the launch of ePOP in late September, 2013. This presentation investigates the propagation delays and timing associated with HF radio waves transversing the plasma in the terrestrial ionosphere. Both the relative and absolute timing of the co-ordinated SuperDARN-RRI experiments will be presented. This knowledge is essential for interpreting HF radio wave propagation effects such as range accuracy, mode-splitting and timing, Doppler shift, and delayed 'echo' signatures, for example.

  2. 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.

  3. 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.

  4. Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

    NASA Astrophysics Data System (ADS)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Holz, D. E.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huang, S.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Islas, G.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jang, H.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Kehl, M. S.; Keitel, D.; Kelley, D. B.; Kells, W.; Kennedy, R.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J.; Kim, K.; Kim, Nam-Gyu; Kim, Namjun; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Koehlenbeck, S. M.; Kokeyama, K.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, P.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lange, J.; Lantz, B.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B. M.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Lockerbie, N. A.; Logue, J.; Lombardi, A. L.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lück, H.; Lundgren, A. P.; Luo, J.; Lynch, R.; Ma, Y.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R. M.; Mageswaran, M.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, K. N.; Mullavey, A.; Munch, J.; Murphy, D. J.; Murray, P. G.; Mytidis, A.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, M.; Neunzert, A.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Patrick, Z.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Pereira, R.; Perreca, A.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S. S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sanchez, E. J.; Sandberg, V.; Sandeen, B.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O. E. S.; Savage, R. L.; Sawadsky, A.; Schale, P.; Schilling, R.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Setyawati, Y.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, N. D.; Smith, R. J. E.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stiles, D.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; Strauss, N. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Tringali, M. C.; Trozzo, L.; Tse, M.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, X.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Wright, J. L.; Wu, G.; Yablon, J.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, H.; Yvert, M.; ZadroŻny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, F.; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, X. J.; Zucker, M. E.; Zuraw, S. E.; Zweizig, J.; Archibald, A. M.; Banaszak, S.; Berndsen, A.; Boyles, J.; Cardoso, R. F.; Chawla, P.; Cherry, A.; Dartez, L. P.; Day, D.; Epstein, C. R.; Ford, A. J.; Flanigan, J.; Garcia, A.; Hessels, J. W. T.; Hinojosa, J.; Jenet, F. A.; Karako-Argaman, C.; Kaspi, V. M.; Keane, E. F.; Kondratiev, V. I.; Kramer, M.; Leake, S.; Lorimer, D.; Lunsford, G.; Lynch, R. S.; Martinez, J. G.; Mata, A.; McLaughlin, M. A.; McPhee, C. A.; Penucci, T.; Ransom, S.; Roberts, M. S. E.; Rohr, M. D. W.; Stairs, I. H.; Stovall, K.; van Leeuwen, J.; Walker, A. N.; Wells, B. L.; LIGO Scientific Collaboration; Virgo Collaboration

    2016-06-01

    We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

  5. Significantly high wave trains in cosmic rays and solar radio flux

    NASA Astrophysics Data System (ADS)

    Mishra, Rajesh Kumar; Agarwal, Rekha

    2016-07-01

    Magnetic field of the Sun disturbs the propagation of cosmic rays during their propagation through the Heliosphere, and introduces variations on time scales that range from hours to millennia. Changes in the heliosphere arising from fluctuations in the Sun's magnetic field mean that galactic cosmic rays are less able to reach the Earth when the Sun is more active so the cosmic ray flux is inversely related to solar activity. In the present work studies has been carried on the occurrence of a large number high amplitude wave train events in cosmic ray intensity and to identify a possible dependence on 10.7-cm solar radio flux (solar activity) using the hourly cosmic ray neutron monitor data for two different ground based neutron monitors. The phase for both high amplitude events as well as for all days is found to significantly deviate towards an earlier hour as compared to the corotational/azimuthal direction. The amplitude of first harmonic and 10.7-cm solar radio flux significantly deviates and reaches to its peak and phase remains in the corotational direction during the years close to solar activity maximum for these high amplitude events. The occurrence of high amplitude wave train events is dominant during solar activity minimum as well as maximum years. The amplitude as well as phase of the first harmonic of cosmic ray intensity during high amplitude events shows significant correlation with solar activity. However, the frequency of occurrence of high amplitude events shows a very nominal dependence on solar activity. Keywords: high amplitude wave trains, cosmic ray, solar activity, 10.7-cm solar radio flux, magnetic field.

  6. 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

  7. 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.

  8. Irregularities in ionospheric plasma clouds: their evolution and effect on radio communication. Technical report

    SciTech Connect

    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.

  9. Monitoring, mapping and prediction of ionospheric scintillation over the Brazilian equatorial and low latitude regions

    NASA Astrophysics Data System (ADS)

    Becker-Guedes, Fabio; de Paula, E. R.; de Rezende, L. F. C.; Stephany, S.; Kantor, I. J.; Muella, M. T. A. H.; Siqueira, P. M.; Correa, K. S.; Dutra, A. P.; Guedes, C.; Takahashi, H.; Silva, J. D. S.

    It is well known, today, that equatorial ionospheric scintillations affect performance of GPS receivers. Scintillation occurs when a radio wave crosses the ionosphere and suffers distortion in phase and amplitude. It also contributes to loss of lock of GPS receivers, resulting decrease of the number of available satellites and consequently yielding poor satellite geometry. Therefore, the required accuracy and positioning precision for aerial navigation are affected. Among other activities, EMBRACE, the space weather program of INPE, is monitoring and mapping the ionospheric scintillation over the South American equatorial and low latitude region in real time. This mapping is available in the internet by means of computer programs that retrieve data from a network of GPS receivers distributed in Brazil. These data are also being used to survey and predict the occurrence of ionospheric scintillation through data mining techniques.

  10. 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.

  11. Global gravity wave activity in the tropopause region from CHAMP radio occultation data

    NASA Astrophysics Data System (ADS)

    Schmidt, T.; de la Torre, A.; Wickert, J.

    2008-08-01

    We discuss the global gravity wave (GW) activity expressed by the specific potential energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean potential energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered.

  12. 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.

  13. 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

  14. Episodes of Ionospheric Disturbances caused by Solar Activity probed using Long Wave Terrestrial Radio Signals

    NASA Astrophysics Data System (ADS)

    Shanmugha Sundaram, GA; Shaik, Manoj

    2016-07-01

    The dynamic spectral record of long wave (LW) radio signals (kHz band) had registered a disturbed condition of the ionosphere region involved with propagation of these signals. The reason for such signatures in the dynamic spectrogram can be accredited to the impact of Solar Energetic Particles (SEP) on the ionosphere along the propagation path of terrestrial long wave radiation, studied using the Multi-Hop propagation model. Points of reflection in the ionosphere directly above specific locations above the Earth where determined. Total Electron Content (TEC) values for such regions were obtained from interpretation of the global positioning system (GPS) data. From a comparisons of such results during periods when the Sun was quiet and active, the magnitude of ionosphere disturbance contributed by the various active solar phenomenae has been determined. The work reported here is based on the impact of Geomagnetic storm (K_{p}=6) on the TEC, that occurred on 16 April 2015. LW radio signals from transmitter locations operated by the United States Navy near Lualualei, Hawaii (Geomagnetic lat 21°25'13.38"}N, Geomagnetic long 158°09'14.35"W) and by France at Rosnay (Geomagnetic lat 46°42'47"N, Geomagnetic long 1°14'39"E) were monitored closely to know the extent of ionospheric impact.

  15. Development of data communication system with ultra high frequency radio wave for implantable artificial hearts.

    PubMed

    Tsujimura, Shinichi; Yamagishi, Hiroto; Sankai, Yoshiyuki

    2009-01-01

    In order to minimize infection risks of patients with artificial hearts, wireless data transmission methods with electromagnetic induction or light have been developed. However, these methods tend to become difficult to transmit data if the external data transmission unit moves from its proper position. To resolve this serious problem, the purpose of this study is to develop a prototype wireless data communication system with ultra high frequency radio wave and confirm its performance. Due to its high-speed communication rate, low power consumption, high tolerance to electromagnetic disturbances, and secure wireless communication, we adopted Bluetooth radio wave technology for our system. The system consists of an internal data transmission unit and an external data transmission unit (53 by 64 by 16 mm, each), and each has a Bluetooth module (radio field intensity: 4 dBm, receiver sensitivity: -80 dBm). The internal unit also has a micro controller with an 8-channel 10-bit A/D converter, and the external unit also has a RS-232C converter. We experimented with the internal unit implanted into pig meat, and carried out data transmission tests to evaluate the performance of this system in tissue thickness of up to 3 mm. As a result, data transfer speeds of about 20 kbps were achieved within the communication distance of 10 m. In conclusion, we confirmed that the system can wirelessly transmit the data from the inside of the body to the outside, and it promises to resolve unstable data transmission due to accidental movements of an external data transmission unit. PMID:19964616

  16. Evaluation of uncertainty in gravity wave potential energy calculations through GPS radio occultation measurements

    NASA Astrophysics Data System (ADS)

    Luna, D.; Alexander, P.; de la Torre, A.

    2013-09-01

    The application of the Global Positioning System (GPS) radio occultation (RO) method to the atmosphere enables the determination of height profiles of temperature, among other variables. From these measurements, gravity wave activity is usually quantified by calculating the potential energy through the integration of the ratio of perturbation and background temperatures between two given altitudes in each profile. The uncertainty in the estimation of wave activity depends on the systematic biases and random errors of the measured temperature, but also on additional factors like the selected vertical integration layer and the separation method between background and perturbation temperatures. In this study, the contributions of different parameters and variables to the uncertainty in the calculation of gravity wave potential energy in the lower stratosphere are investigated and quantified. In particular, a Monte Carlo method is used to evaluate the uncertainty that results from different GPS RO temperature error distributions. In addition, our analysis shows that RO data above 30 km height becomes dubious for gravity waves potential energy calculations.

  17. A new approach to global gravity wave momentum flux determination from GPS radio occultation data

    NASA Astrophysics Data System (ADS)

    Faber, A.; Llamedo, P.; Schmidt, T.; de la Torre, A.; Wickert, J.

    2013-03-01

    GPS Radio Occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions offering the possibility for global monitoring of the vertical temperature structure and atmospheric wave parameters. The six satellites constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. The horizontal wavenumber is derived by the ratio of the phase shift and the spatial distance between adjacent temperature fluctuation profiles at a given altitude, following the method by Ern et al. (2004). A new method for the determination of the real horizontal wavelength from triads of vertical profiles is presented and applied to the COSMIC data. The horizontal and vertical wavelength, the specific potential energy (Ep) and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  18. 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.

  19. GNSS Phase Scintillation and Cycle Slips Occurrence at High Latitudes: Climatology and Forecasting

    NASA Astrophysics Data System (ADS)

    Prikryl, Paul; Jayachandran, Periyadan T.; Chadwick, Richard; Kelly, Todd D.

    2014-05-01

    Space weather impacts the operation of modern technology that relies on Global Navigation Satellite Systems (GNSS). Ionospheric scintillation (rapid fluctuation of radio wave amplitude and phase) degrades GPS positional accuracy and causes cycle slips leading to loss of lock that affects performance of radio communication and navigation systems. At high latitudes, GPS scintillation and total electron content has been monitored by the Canadian High Arctic Ionospheric Network (CHAIN). GPS phase scintillation and cycle slips, as a function of magnetic latitude and local time, occur on the dayside in the ionospheric cusp, in the nightside auroral oval, and in the polar cap. Interplanetary coronal mass ejections and corotating interaction regions on the leading edge of high-speed streams are closely correlated with the occurrence of scintillation at high latitudes. Results of a superposed epoch analysis of time series of phase scintillation and cycle slips occurrence keyed by arrival times of high speed solar wind streams and interplanetary coronal mass ejections are presented. Based on these results, a method of probabilistic forecasting of high-latitude phase scintillation occurrence is proposed.

  20. 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

  1. 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.

  2. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  3. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    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.

  4. 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.

  5. 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.

  6. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    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.

  7. 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.

  8. Direct imaging of radio-frequency modes via traveling wave magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Tonyushkin, A.; Deelchand, D. K.; Van de Moortele, P.-F.; Adriany, G.; Kiruluta, A.

    2016-01-01

    We demonstrate an experimental method for direct 2D and 3D imaging of magnetic radio-frequency (rf) field distribution in metal-dielectric structures based on traveling wave (TW) magnetic resonance imaging (MRI) at ultra-high field (>7 T). The typical apparatus would include an ultra-high field whole body or small bore MRI scanner, waveguide elements filled with MRI active dielectrics with predefined electric and magnetic properties, and TW rf transmit-receive probes. We validated the technique by obtaining TW MR images of the magnetic field distribution of the rf modes of circular waveguide filled with deionized water in a 16.4 T small-bore MRI scanner and compared the MR images with numerical simulations. Our MRI technique opens up a practical non-perturbed way of imaging of previously inaccessible rf field distribution of modes inside various shapes metal waveguides with inserted dielectric objects, including waveguide mode converters and transformers.

  9. Radio-Wave Heating of Iron Oxide Nanoparticles Can Regulate Plasma Glucose in Mice

    PubMed Central

    Stanley, Sarah A.; Gagner, Jennifer E.; Damanpour, Shadi; Yoshida, Mitsukuni; Dordick, Jonathan S.; Friedman, Jeffrey M.

    2013-01-01

    Medical applications of nanotechnology typically focus on drug delivery and biosensors. Here, we combine nanotechnology and bioengineering to demonstrate that nanoparticles can be used to remotely regulate protein production in vivo. We decorated a modified temperature-sensitive channel, TRPV1, with antibody-coated iron oxide nanoparticles that are heated in a low-frequency magnetic field. When local temperature rises, TRPV1 gates calcium to stimulate synthesis and release of bioengineered insulin driven by a Ca2+-sensitive promoter. Studying tumor xenografts expressing the bioengineered insulin gene, we show that exposure to radio waves stimulates insulin release from the tumors and lowers blood glucose in mice. We further show that cells can be engineered to synthesize genetically encoded ferritin nanoparticles and inducibly release insulin. These approaches provide a platform for using nanotechnology to activate cells. PMID:22556257

  10. Blood-brain barrier disruption by continuous-wave radio frequency radiation.

    PubMed

    Sirav, Bahriye; Seyhan, Nesrin

    2009-01-01

    The increasing use of cellular phones and the increasing number of associated base stations are becoming a widespread source of non ionizing electromagnetic radiation. Some biological effects are likely to occur even at low-level EM fields. This study was designed to investigate the effects of 900 and 1,800 MHz Continuous Wave Radio Frequency Radiation (CW RFR) on the permeability of Blood Brain Barrier (BBB) of rats. Results have shown that 20 min RFR exposure of 900 and 1,800 MHz induces an effect and increases the permeability of BBB of male rats. There was no change in female rats. The scientific evidence on RFR safety or harm remains inconclusive. More studies are needed to demonstrate the effects of RFR on the permeability of BBB and the mechanisms of that breakdown. PMID:19811403