Sample records for microwave anomalous emission

  1. Anomalous Microwave Emission

    E-print Network

    A. Kogut

    1999-02-22

    Improved knowledge of diffuse Galactic emission is important to maximize the scientific return from scheduled CMB anisotropy missions. Cross-correlation of microwave maps with maps of the far-IR dust continuum show a ubiquitous microwave emission component whose spatial distribution is traced by far-IR dust emission. The spectral index of this emission, beta_{radio} = -2.2 (+0.5 -0.7) is suggestive of free-free emission but does not preclude other candidates. Comparison of H-alpha and microwave results show that both data sets have positive correlations with the far-IR dust emission. Microwave data, however, are consistently brighter than can be explained solely from free-free emission traced by H-alpha. This ``anomalous'' microwave emission can be explained as electric dipole radiation from small spinning dust grains. The anomalous component at 53 GHz is 2.5 times as bright as the free-free emission traced by H-alpha, providing an approximate normalization for models with significant spinning dust emission.

  2. AMI OBSERVATIONS OF THE ANOMALOUS MICROWAVE EMISSION IN THE PERSEUS MOLECULAR CLOUD

    SciTech Connect

    Tibbs, C. T. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Scaife, A. M. M. [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Dickinson, C.; Davies, R. D.; Davis, R. J.; Watson, R. A. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Paladini, R. [NASA Herschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Grainge, K. J. B., E-mail: ctibbs@ipac.caltech.edu [Astrophysics Group, Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2013-05-10

    We present observations of the known anomalous microwave emission region, G159.6-18.5, in the Perseus molecular cloud at 16 GHz performed with the Arcminute Microkelvin Imager Small Array. These are the highest angular resolution observations of G159.6-18.5 at microwave wavelengths. By combining these microwave data with infrared observations between 5.8 and 160 {mu}m from the Spitzer Space Telescope, we investigate the existence of a microwave-infrared correlation on angular scales of {approx}2'. We find that the overall correlation appears to increase toward shorter infrared wavelengths, which is consistent with the microwave emission being produced by electric dipole radiation from small, spinning dust grains. We also find that the microwave-infrared correlation peaks at 24 {mu}m (6.7{sigma}), suggesting that the microwave emission is originating from a population of stochastically heated small interstellar dust grains rather than polycyclic aromatic hydrocarbons.

  3. Constraints on Free-Free Emission from Anomalous Microwave Emission Sources in the Perseus Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Tibbs, C. T.; Paladini, R.; Dickinson, C.; Mason, B. S.; Casassus, S.; Cleary, K.; Davies, R. D.; Davis, R. J.; Watson, R. A.

    2013-06-01

    We present observations performed with the Green Bank Telescope at 1.4 and 5 GHz of three strips coincident with the anomalous microwave emission features previously identified in the Perseus molecular cloud at 33 GHz with the Very Small Array. With these observations we determine the level of the low frequency (~1-5 GHz) emission. We do not detect any significant extended emission in these regions and we compute conservative 3? upper limits on the fraction of free-free emission at 33 GHz of 27%, 12%, and 18% for the three strips, indicating that the level of the emission at 1.4 and 5 GHz cannot account for the emission observed at 33 GHz. Additionally, we find that the low frequency emission is not spatially correlated with the emission observed at 33 GHz. These results indicate that the emission observed in the Perseus molecular cloud at 33 GHz, is indeed in excess over the low frequency emission, hence confirming its anomalous nature.

  4. CONSTRAINTS ON FREE-FREE EMISSION FROM ANOMALOUS MICROWAVE EMISSION SOURCES IN THE PERSEUS MOLECULAR CLOUD

    SciTech Connect

    Tibbs, C. T. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Paladini, R. [NASA Herschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Dickinson, C.; Davies, R. D.; Davis, R. J.; Watson, R. A. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Mason, B. S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Casassus, S. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Cleary, K., E-mail: ctibbs@ipac.caltech.edu [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-06-20

    We present observations performed with the Green Bank Telescope at 1.4 and 5 GHz of three strips coincident with the anomalous microwave emission features previously identified in the Perseus molecular cloud at 33 GHz with the Very Small Array. With these observations we determine the level of the low frequency ({approx}1-5 GHz) emission. We do not detect any significant extended emission in these regions and we compute conservative 3{sigma} upper limits on the fraction of free-free emission at 33 GHz of 27%, 12%, and 18% for the three strips, indicating that the level of the emission at 1.4 and 5 GHz cannot account for the emission observed at 33 GHz. Additionally, we find that the low frequency emission is not spatially correlated with the emission observed at 33 GHz. These results indicate that the emission observed in the Perseus molecular cloud at 33 GHz, is indeed in excess over the low frequency emission, hence confirming its anomalous nature.

  5. Planck early results. XX. New light on anomalous microwave emission from spinning dust grains

    Microsoft Academic Search

    P. A. R. Ade; N. Aghanim; M. Arnaud; M. Ashdown; J. Aumont; C. Baccigalupi; A. Balbi; A. J. Banday; R. B. Barreiro; J. G. Bartlett; E. Battaner; K. Benabed; A. Benoît; J.-P. Bernard; M. Bersanelli; R. Bhatia; J. J. Bock; A. Bonaldi; J. R. Bond; J. Borrill; F. Boulanger; M. Bucher; C. Burigana; P. Cabella; B. Cappellini; J.-F. Cardoso; S. Casassus; A. Catalano; L. Cayón; A. Challinor; A. Chamballu; R.-R. Chary; X. Chen; L.-Y. Chiang; C. Chiang; P. R. Christensen; D. L. Clements; S. Colombi; F. Couchot; A. Coulais; B. P. Crill; F. Cuttaia; L. Danese; R. D. Davies; R. J. Davis; P. de Bernardis; G. de Gasperis; A. de Rosa; G. de Zotti; J. Delabrouille; J.-M. Delouis; C. Dickinson; S. Donzelli; O. Doré; U. Dörl; M. Douspis; X. Dupac; G. Efstathiou; T. A. Enßlin; H. K. Eriksen; F. Finelli; O. Forni; M. Frailis; E. Franceschi; S. Galeotta; K. Ganga; R. T. Génova-Santos; M. Giard; G. Giardino; Y. Giraud-Héraud; J. González-Nuevo; K. M. Górski; S. Gratton; A. Gregorio; A. Gruppuso; F. K. Hansen; D. Harrison; G. Helou; S. Henrot-Versillé; D. Herranz; S. R. Hildebrandt; E. Hivon; M. Hobson; W. A. Holmes; W. Hovest; R. J. Hoyland; K. M. Huffenberger; T. R. Jaffe; A. H. Jaffe; W. C. Jones; M. Juvela; E. Keihänen; R. Keskitalo; T. S. Kisner; R. Kneissl; L. Knox; H. Kurki-Suonio; G. Lagache; A. Lähteenmäki; J.-M. Lamarre; A. Lasenby; R. J. Laureijs; C. R. Lawrence; S. Leach; R. Leonardi; P. B. Lilje; M. Linden-Vørnle; M. López-Caniego; P. M. Lubin; J. F. Macías-Pérez; C. J. MacTavish; B. Maffei; D. Maino; N. Mandolesi; R. Mann; M. Maris; D. J. Marshall; E. Martínez-González; S. Masi; S. Matarrese; F. Matthai; P. Mazzotta; P. McGehee; P. R. Meinhold; A. Melchiorri; L. Mendes; A. Mennella; S. Mitra; M.-A. Miville-Deschênes; A. Moneti; L. Montier; G. Morgante; D. Mortlock; D. Munshi; A. Murphy; P. Naselsky; P. Natoli; C. B. Netterfield; H. U. Nørgaard-Nielsen; F. Noviello; D. Novikov; I. Novikov; I. J. O'Dwyer; S. Osborne; F. Pajot; R. Paladini; B. Partridge; F. Pasian; G. Patanchon; T. J. Pearson; M. Peel; O. Perdereau; L. Perotto; F. Perrotta; F. Piacentini; M. Piat; S. Plaszczynski; P. Platania; E. Pointecouteau; G. Polenta; N. Ponthieu; T. Poutanen; G. Prézeau; P. Procopio; S. Prunet; J.-L. Puget; W. T. Reach; R. Rebolo; W. Reich; M. Reinecke; C. Renault; S. Ricciardi; T. Riller; I. Ristorcelli; G. Rocha; C. Rosset; M. Rowan-Robinson; J. A. Rubiño-Martín; B. Rusholme; M. Sandri; D. Santos; G. Savini; D. Scott; M. D. Seiffert; P. Shellard; G. F. Smoot; J.-L. Starck; F. Stivoli; V. Stolyarov; R. Stompor; R. Sudiwala; J.-F. Sygnet; J. A. Tauber; L. Terenzi; L. Toffolatti; M. Tomasi; J.-P. Torre; M. Tristram; J. Tuovinen; G. Umana; L. Valenziano; J. Varis; L. Verstraete; P. Vielva; F. Villa; N. Vittorio; L. A. Wade; B. D. Wandelt; R. Watson; A. Wilkinson; N. Ysard; D. Yvon; A. Zacchei; A. Zonca

    2011-01-01

    Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ~10-60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and rho Ophiuchi molecular clouds. The spectra are well fitted by a combination of free-free radiation, cosmic microwave background, thermal dust, and electric dipole radiation from

  6. New Radio Observations of Anomalous Microwave Emission in the H II Region RCW175

    NASA Astrophysics Data System (ADS)

    Battistelli, E. S.; Carretti, E.; Cruciani, A.; de Bernardis, P.; Génova-Santos, R.; Masi, S.; Naldi, A.; Paladini, R.; Piacentini, F.; Tibbs, C. T.; Verstraete, L.; Ysard, N.

    2015-03-01

    We have observed the H II region RCW175 with the 64 m Parkes telescope at 8.4 GHz and 13.5 GHz in total intensity, and at 21.5 GHz in both total intensity and polarization. High angular resolution ranging from 1 to 2.4 arcmin, high sensitivity, and polarization capability enable us to perform a detailed study of the different constituents of the H II region. For the first time, we resolve three distinct regions at microwave frequencies, two of which are part of the same annular diffuse structure. Our observations enable us to confirm the presence of anomalous microwave emission (AME) from RCW175. Fitting the integrated flux density across the entire region with the currently available spinning dust models, using physically motivated assumptions, indicates the presence of at least two spinning dust components: a warm component (T gas = 5800 K) with a relatively large hydrogen number density n H = 26.3/cm3 and a cold component (T gas = 100 K) with a hydrogen number density of n H = 150/cm3. The present study is an example highlighting the potential of using high angular-resolution microwave data to break model parameter degeneracies. Thanks to the spectral coverage and angular resolution of the Parkes observations, we have been able to derive one of the first AME/excess maps, at 13.5 GHz, showing clear evidence that the bulk of the anomalous emission arises in particular from one of the source components, with some additional contribution from the diffuse structure. A cross-correlation analysis with thermal dust emission has shown a high degree of correlation with one of the regions within RCW175. In the center of RCW175, we find an average polarized emission at 21.5 GHz of 2.2 ± 0.2(rand.) ± 0.3(sys.)% of the total emission, where we have included both systematic and statistical uncertainties at 68% CL. This polarized emission could be due to sub-dominant synchrotron emission from the region and is thus consistent with very faint or non-polarized emission associated with AME.

  7. DETECTION OF ANOMALOUS MICROWAVE EMISSION IN THE PLEIADES REFLECTION NEBULA WITH WILKINSON MICROWAVE ANISOTROPY PROBE AND THE COSMOSOMAS EXPERIMENT

    SciTech Connect

    Genova-Santos, R.; Rebolo, R.; Rubino-Martin, J. A.; Lopez-Caraballo, C. H.; Hildebrandt, S. R. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, E-38200 La Laguna, Tenerife (Spain)

    2011-12-10

    We present evidence for anomalous microwave emission (AME) in the Pleiades reflection nebula, using data from the seven-year release of the Wilkinson Microwave Anisotropy Probe and from the COSMOSOMAS (Cosmological Structures on Medium Angular Scales) experiment. The flux integrated in a 1 Degree-Sign radius around R.A. = 56.{sup 0}24, decl. = 23.{sup 0}78 (J2000) is 2.15 {+-} 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data show no significant emission, but allow one to set upper limits of 0.94 and 1.58 Jy (99.7% confidence level), respectively, at 10.9 and 14.7 GHz, which are crucial to pin down the AME spectrum at these frequencies, and to discard any other emission mechanisms which could have an important contribution to the signal detected at 22.8 GHz. We estimate the expected level of free-free emission from an extinction-corrected H{alpha} template, while the thermal dust emission is characterized from infrared DIRBE data and extrapolated to microwave frequencies. When we deduct the contribution from these two components at 22.8 GHz, the residual flux, associated with AME, is 2.12 {+-} 0.12 Jy (17.7{sigma}). The spectral energy distribution from 10 to 60 GHz can be accurately fitted with a model of electric dipole emission from small spinning dust grains distributed in two separated phases of molecular and atomic gas, respectively. The dust emissivity, calculated by correlating the 22.8 GHz data with 100 {mu}m data, is found to be 4.36 {+-} 0.17 {mu}K (MJy sr{sup -1}){sup -1}, a value considerably lower than in typical AME clouds, which present emissivities of {approx}20 {mu}K (MJy sr{sup -1}){sup -1}, although higher than the 0.2 {mu}K (MJy sr{sup -1}){sup -1} of the translucent cloud LDN 1780, where AME has recently been claimed. The physical properties of the Pleiades nebula, in particular its low extinction A{sub V} {approx} 0.4, indicate that this is indeed a much less opaque object than those where AME has usually been studied. This fact, together with the broad knowledge of the stellar content of this region, provides an excellent testbed for AME characterization in physical conditions different from those generally explored up to now.

  8. Planck early results. XX. New light on anomalous microwave emission from spinning dust grains

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Balbi, A.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Bernard, J.-P.; Bersanelli, M.; Bhatia, R.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Cabella, P.; Cappellini, B.; Cardoso, J.-F.; Casassus, S.; Catalano, A.; Cayón, L.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, L.-Y.; Chiang, C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Couchot, F.; Coulais, A.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Gasperis, G.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Donzelli, S.; Doré, O.; Dörl, U.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Génova-Santos, R. T.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hovest, W.; Hoyland, R. J.; Huffenberger, K. M.; Jaffe, T. R.; Jaffe, A. H.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knox, L.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Leach, S.; Leonardi, R.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; MacTavish, C. J.; Maffei, B.; Maino, D.; Mandolesi, N.; Mann, R.; Maris, M.; Marshall, D. J.; Martínez-González, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, A.; Naselsky, P.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Pajot, F.; Paladini, R.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Peel, M.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Poutanen, T.; Prézeau, G.; Procopio, P.; Prunet, S.; Puget, J.-L.; Reach, W. T.; Rebolo, R.; Reich, W.; Reinecke, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, P.; Smoot, G. F.; Starck, J.-L.; Stivoli, F.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Torre, J.-P.; Tristram, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Varis, J.; Verstraete, L.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Watson, R.; Wilkinson, A.; Ysard, N.; Yvon, D.; Zacchei, A.; Zonca, A.

    2011-12-01

    Anomalous microwave emission (AME) has been observed by numerous experiments in the frequency range ~10-60 GHz. Using Planck maps and multi-frequency ancillary data, we have constructed spectra for two known AME regions: the Perseus and ? Ophiuchi molecular clouds. The spectra are well fitted by a combination of free-free radiation, cosmic microwave background, thermal dust, and electric dipole radiation from small spinning dust grains. The spinning dust spectra are the most precisely measured to date, and show the high frequency side clearly for the first time. The spectra have a peak in the range 20-40 GHz and are detected at high significances of 17.1? for Perseus and 8.4? for ? Ophiuchi. In Perseus, spinning dust in the dense molecular gas can account for most of the AME; the low density atomic gas appears to play a minor role. In ? Ophiuchi, the ~30 GHz peak is dominated by dense molecular gas, but there is an indication of an extended tail at frequencies 50-100 GHz, which can be accounted for by irradiated low density atomic gas. The dust parameters are consistent with those derived from other measurements. We have also searched the Planck map at 28.5 GHz for candidate AME regions, by subtracting a simple model of the synchrotron, free-free, and thermal dust. We present spectra for two of the candidates; S140 and S235 are bright Hii regions that show evidence for AME, and are well fitted by spinning dust models. Corresponding author: C. Dickinson, Clive.Dickinson@manchester.ac.uk

  9. Planck intermediate results. XV. A study of anomalous microwave emission in Galactic clouds

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Arnaud, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Casassus, S.; Catalano, A.; Chamballu, A.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson; , C.; Diego, J. M.; Donzelli, S.; Doré, O.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Franceschi, E.; Galeotta, S.; Ganga, K.; Génova-Santos, R. T.; Ghosh, T.; Giard, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Patanchon, G.; Pearson, T. J.; Peel, M.; Perdereau, O.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reich, W.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Tibbs, C. T.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Varis, J.; Verstraete, L.; Vielva, P.; Villa, F.; Wandelt, B. D.; Watson, R.; Wilkinson, A.; Ysard, N.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-05-01

    Anomalous microwave emission (AME) is believed to be due to electric dipole radiation from small spinning dust grains. The aim of this paper is a statistical study of the basic properties of AME regions and the environment in which they emit. We used WMAP and Planck maps, combined with ancillary radio and IR data, to construct a sample of 98 candidate AME sources, assembling SEDs for each source using aperture photometry on 1°-smoothed maps from 0.408 GHz up to 3000 GHz. Each spectrum is fitted with a simple model of free-free, synchrotron (where necessary), cosmic microwave background (CMB), thermal dust, and spinning dust components. We find that 42 of the 98 sources have significant (>5?) excess emission at frequencies between 20 and 60 GHz. An analysis of the potential contribution of optically thick free-free emission from ultra-compact H ii regions, using IR colour criteria, reduces the significant AME sample to 27 regions. The spectrum of the AME is consistent with model spectra of spinning dust. Peak frequencies are in the range 20-35 GHz except for the California nebula (NGC 1499), which appears to have a high spinning dust peak frequency of (50 ± 17) GHz. The AME regions tend to be more spatially extended than regions with little or no AME. The AME intensity is strongly correlated with the sub-millimetre/IR flux densities and comparable to previous AME detections in the literature. AME emissivity, defined as the ratio of AME to dust optical depth, varies by an order of magnitude for the AME regions. The AME regions tend to be associated with cooler dust in the range 14-20 K and an average emissivity index, ?d, of +1.8, while the non-AME regions are typically warmer, at 20-27 K. In agreement with previous studies, the AME emissivity appears to decrease with increasing column density. This supports the idea of AME originating from small grains that are known to be depleted in dense regions, probably due to coagulation onto larger grains. We also find a correlation between the AME emissivity (and to a lesser degree the spinning dust peak frequency) and the intensity of the interstellar radiation field, G0. Modelling of this trend suggests that both radiative and collisional excitation are important for the spinning dust emission. The most significant AME regions tend to have relatively less ionized gas (free-free emission), although this could be a selection effect. The infrared excess, a measure of the heating of dust associated with H ii regions, is typically >4 for AME sources, indicating that the dust is not primarily heated by hot OB stars. The AME regions are associated with known dark nebulae and have higher 12 ?m/25 ?m ratios. The emerging picture is that the bulk of the AME is coming from the polycyclic aromatic hydrocarbons and small dust grains from the colder neutral interstellar medium phase.

  10. Searching for the Carrier/s of Anomalous Microwave Emission: An AKARI PAH-range Analysis of Probable Electric Dipole Emitting Regions

    NASA Astrophysics Data System (ADS)

    Bell, A. C.; Onaka, T.; Sakon, I.; Doi, Y.; Usui, F.; Ishihara, D.; Kaneda, H.; Giard, M.; Lee, H.-G.; Ohsawa, R. Mori-Ito, T.; Hammonds, M.; Yasui, C.; Nakamura, T.

    2014-03-01

    In the stream of interstellar medium inquiry, many new species of interstellar dust have been modeled and discovered. Their modes of interaction and evolution are beginning to be understood. In recent years a peculiar new feature has appeared in microwave surveys. Anomalous microwave emission (AME), a continuum excess between 10 and 50Ghz, has been correlated with vibrational dust emission, leading to the popular suggestion that this anomaly is electric dipole emission from spinning dust (Draine & Lazarian 1998). The observed frequencies suggest that spinning grains should be on the order of 10nm in size, hinting at polycyclic aromatic hydrocarbon molecules (PAHs). We present data from AKARI/Infrared Camera (IRC, Onaka et al. 2007) , because of the effective PAH / unidentified infrared band (UIR) coverage of its 9um survey. We investigate a possible role of PAHs within a few regions showing strong AME in the Planck Low Frequency Instrument (LFI, Planck Collaboration, et al. 2013) data. We include the well-studied Perseus and rhoOphiuchi clouds. We present our results as abundance maps for dust emitting around 9um, and 100um via IRAS/IRIS. Part of the AME in these regions may actually be attributed to thermal dust emission. The star forming nature of these targets could also be masking the vibrational modes of PAHs which may be present there. Further investigation for different galactic environments is suggested.

  11. Anomalous Radio Emission from Dust in the Helix

    Microsoft Academic Search

    S. Casassus; A. C. S. Readhead; T. J. Pearson; L.-Å. Nyman; M. C. Shepherd; L. Bronfman

    2004-01-01

    A by-product of experiments designed to map the cosmic microwave background is the recent detection of a new component of foreground Galactic emission. The anomalous foreground at ~10-30 GHz, unexplained by traditional emission mechanisms, correlates with 100 mum dust emission. We use planetary nebulae (PNs) as astrophysical laboratories to test known radio emission processes and report that in the Helix

  12. Microwave emissions from snow

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.

    1984-01-01

    The radiation emitted from dry and wet snowpack in the microwave region (1 to 100 GHz) is discussed and related to ground observations. Results from theoretical model calculations match the brightness temperatures obtained by truck mounted, airborne and spaceborne microwave sensor systems. Snow wetness and internal layer structure complicate the snow parameter retrieval algorithm. Further understanding of electromagnetic interaction with snowpack may eventually provide a technique to probe the internal snow properties

  13. Evidence for Anomalous Dust-correlated Emission at 8 GHz

    NASA Astrophysics Data System (ADS)

    Lu, Michelle; Dunkley, Joanna; Page, Lyman

    2012-04-01

    In 1969 Edward Conklin measured the anisotropy in celestial emission at 8 GHz with a resolution of 16fdg2 and used the data to report a detection of the cosmic microwave background dipole. Given the paucity of 8 GHz observations over large angular scales and the clear evidence for non-power-law Galactic emission near 8 GHz, a new analysis of Conklin's data is informative. In this paper, we compare Conklin's data to that from Haslam et al. (0.4 GHz), Reich and Reich (1.4 GHz), and the Wilkinson Microwave Anisotropy Probe (WMAP; 23-94 GHz). We show that the spectral index between Conklin's data and the 23 GHz WMAP data is ? = -1.7 ± 0.1, where we model the emission temperature as Tvprop??. Free-free emission has ? ? - 2.15 and synchrotron emission has ? ? - 2.7 to -3. Thermal dust emission (? ? 1.7) is negligible at 8 GHz. We conclude that there must be another distinct non-power-law component of diffuse foreground emission that emits near 10 GHz, consistent with other observations in this frequency range. By comparing to the full complement of data sets, we show that a model with an anomalous emission component, assumed to be spinning dust, is preferred over a model without spinning dust at 5? (??2 = 31). However, the source of the new component cannot be determined uniquely.

  14. AN ANOMALOUS COMPONENT OF GALACTIC EMISSION

    Microsoft Academic Search

    E. M. LEITCH; T. J. P EARSON; S. T. Myers

    1997-01-01

    We present results from microwave background observations at the Owens Valley Radio Observatory. These observations, at 14.5 and 32 GHz, are designed to detect intrinsic anisotropy on scales of 79-229. After point-source removal, we detect significant emission with temperature spectral index b3 22 toward the north celestial pole (NCP). Comparison of our data with the IRAS 100 mm map of

  15. Electron Emission Mechanism of Microwave Discharge Neutralizer

    Microsoft Academic Search

    Noriyoshi Onodera; Haruki Takegahara; Kazutaka Nishiyama; Ikko Funaki; Hitoshi Kuninaka

    2002-01-01

    Institute of Space and Astronautical Science has developed a cathodeless microwave discharge neutralizer for the microwave ion engine system. In order to clarify the electron emission mechanism of the microwave neutralizer, electron current characteristics as well as plasma parameters inside the neuralizer were measured. The electron current was greatly influenced by the material of the neutralizer orifice. Among several materials

  16. Emissions from cooking microwave popcorn.

    PubMed

    Rosati, Jacky A; Krebs, Kenneth A; Liu, Xiaoyu

    2007-01-01

    This study characterized chemicals released into a chamber in the process of cooking microwave popcorn. Seventeen types of microwave popcorn from eight different brands were studied. The work proceeded in two phases: phase one investigated chemicals emitted during popping and opening, phase two investigated chemicals emitted at discrete intervals from 0-40 minutes post-pop opening. The research was performed using a microwave oven enclosed in a chamber with ports for air sampling of particulate matter (PM) and volatile organic compounds (VOCs). VOCs in the air samples were identified and quantified using gas chromatography/mass spectrometry (GC/MS). PM was characterized using both an aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) to cover a full range of emitted sizes. The compounds measured during popping and opening included butter flavoring components such as diacetyl, butyric acid, acetoin, propylene glycol, 2-nonanone, and triacetin and bag components such as p-xylene and perfluorinated alcohol 8:2 telomer. The greatest chemical quantity is emitted when the bag is opened post-popping; more than 80% of the total chemical emissions occur at this time. PMID:17987444

  17. Microwave Emission at High Galactic Latitudes

    E-print Network

    A. Kogut; G. Hinshaw; A. J. Banday; C. L. Bennett; K. Gorski; G. F. Smoot; E. L. Wright

    1996-01-12

    We use the COBE Differential Microwave Radiometers (DMR) 4-year sky maps to model Galactic microwave emission at high latitudes (|b| > 20 deg). Cross-correlation of the DMR maps with Galactic template maps detects fluctuations in the high-latitude microwave sky brightness with the angular variation of the DIRBE far-infrared dust maps and a frequency dependence consistent with a superposition of dust and free-free emission. We find no significant correlations between the DMR maps and various synchrotron templates. On the largest angular scales (e.g., quadrupole), Galactic emission is comparable in amplitude to the anisotropy in the cosmic microwave background (CMB). The CMB quadrupole amplitude, after correction for Galactic emission, has amplitude $Q_{rms}$ = 10.7 uK with random uncertainty 3.6 uK and systematic uncertainty 7.1 uK from uncertainty in our knowledge of Galactic microwave emission.

  18. Separation of anomalous and synchrotron emissions using WMAP polarization data

    NASA Astrophysics Data System (ADS)

    Miville-Deschênes, M.-A.; Ysard, N.; Lavabre, A.; Ponthieu, N.; Macías-Pérez, J. F.; Aumont, J.; Bernard, J. P.

    2008-11-01

    Context: Apart from its contribution to cosmology, the WMAP data brings new information on the Galactic interstellar medium. In particular the polarization data provide constraints on the Galactic magnetic field and the synchrotron emission, while the intensity data can be used to study the anomalous microwave emission. Aims: The main goals of this study is to use the information from both WMAP intensity and polarization data to do a separation of the Galactic components, with a focus on the synchrotron and anomalous emissions. Methods: Our analysis is made at 23 GHz where the signal-to-noise ratio is the highest and the estimate of the CMB map is less critical. Our estimate of the synchrotron intensity is based on an extrapolation of the Haslam 408 MHz data with a spatially varying spectral index constrained by the WMAP 23 GHz polarization data and a bi-symmetrical spiral model of the galactic magnetic field with a turbulent part following a -5/3 power law spectrum. Results: The 23 GHz polarization data are found to be compatible with a magnetic field with a pitch angle p=-8.5° and an amplitude of the turbulent part of the magnetic field 0.57 times the local value of the field, in agreement with what is found using rotation measures of pulsars and polarized extinction by dust. The synchrotron spectral index between 408 MHz and 23 GHz obtained from polarization data and our model of the magnetic field has a mean value of ? s=-3.00 with a limited spatial variation with a standard deviation of 0.06. When thermal dust, free-free and synchrotron are removed from the WMAP intensity data, the residual anomalous emission is highly correlated with thermal dust emission with a spectrum in agreement with spinning dust models. Conclusions: Considering a classical model of the large scale Galactic magnetic field, we show that the polarization data of WMAP are in favor of a soft synchrotron intensity highly correlated with the 408 MHz data. Furthermore the combination of the WMAP polarization and intensity data brings strong evidence for the presence of unpolarized spinning dust emission in the 20-60 GHz range. In preparation for the Planck mission this joint analysis of polarization and intensity data opens new perspective on the study of the Galactic interstellar medium and on the component separation exercise.

  19. Microwave emission and scattering from vegetated terrain

    E-print Network

    Sibley, Terrell Gene

    1973-01-01

    Major Subject: Electrical Engineering MICROWAVE EMISSION AND SCATTERING FROM VEGETATED TERRAIN A Thesis by TERRELL GENE SIBLEY Approved as to style and content by: iran o o t e ea epart nt em er Aug us t 19 7 3 ABSTRACT Microwave Emission... and for helping to prepare the final manuscript. Funding for this project was provided by the National Aeronautics and Space Administration under Grant NGL 44- 001-001, vi TABLE OF CONTENTS ~Ch1 tOl' ~pa e I. INTRODUCTION The Potential for Microwave...

  20. Microwave emissions from police radar

    E-print Network

    Fink, John Michael

    1994-01-01

    The purpose of this study was to evaluate police officers exposures to microwaves emitted by traffic radar units at the ocular and testicular level. Additionally, comparisons were made of the radar manufacturers published maximum power density...

  1. Microwave Emission by Dust: Mechanisms, Properties and Prospects for ISM Studies

    E-print Network

    Lazarian A

    1998-11-03

    I review my work with Bruce Draine on dust emissivity at microwave frequencies (3 cm - 3 mm). This emissivity explains the recently detected "anomalous" component of the galactic foreground emission. Both small (a<0.001 micron) and large grains contribute to this emission. Small grains have electric dipole moments and emit while they rotate; the microwave emission of large grains is mostly due to magneto-dipole radiation. Most efficient magneto-dipole emitters are strongly magnetic, e.g. ferrimagnetic or ferromagnetic, materials. The relative role of the two mechanisms can be established through observations of microwave emissivity from dark clouds. New microwave window is a window of opportunity for interstellar studies. Magnetic fields inside dark clouds may be successfully studied via microwave polarization. Microwave emissivity constrains the abundance of strongly magnetic materials. For instance, the available data at 90 GHz indicate that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in ``GEMS''). Future missions, e.g. MAP and PLANCK, will bring a wealth of microwave data that can be successfully used to study ISM. Such a study would be appreciated by cosmologists who franticly try to remove all foregrounds from their data.

  2. Microwave Emissions from Police Radar

    Microsoft Academic Search

    J. M. Fink; J. P. Wagner; J. J. Congleton; J. C. Rock

    1999-01-01

    This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation

  3. Beyond Anderson Localization in 1D: Anomalous Localization of Microwaves in Random Waveguides

    NASA Astrophysics Data System (ADS)

    Fernández-Marín, A. A.; Méndez-Bermúdez, J. A.; Carbonell, J.; Cervera, F.; Sánchez-Dehesa, J.; Gopar, V. A.

    2014-12-01

    Experimental evidence demonstrating that anomalous localization of waves can be induced in a controllable manner is reported. A microwave waveguide with dielectric slabs randomly placed is used to confirm the presence of anomalous localization. If the random spacing between slabs follows a distribution with a power-law tail (Lévy-type distribution), unconventional properties in the microwave-transmission fluctuations take place revealing the presence of anomalous localization. We study both theoretically and experimentally the complete distribution of the transmission through random waveguides characterized by ? =1 /2 ("Lévy waveguides") and ? =3 /4 , ? being the exponent of the power-law tail of the Lévy-type distribution. As we show, the transmission distributions are determined by only two parameters, both of them experimentally accessible. Effects of anomalous localization on the transmission are compared with those from the standard Anderson localization.

  4. Microwave emissions from police radar.

    PubMed

    Fink, J M; Wagner, J P; Congleton, J J; Rock, J C

    1999-01-01

    This study evaluated police officers' exposures to microwaves emitted by traffic radar units. Exposure measurements were taken at approximated ocular and testicular levels of officers seated in patrol vehicles. Comparisons were made of the radar manufacturers' published maximum power density specifications and actual measured power densities taken at the antenna faces of those units. Four speed-enforcement agencies and one transportation research institute provided 54 radar units for evaluation; 17 different models, encompassing 4 frequency bands and 3 antenna configurations, were included. Four of the 986 measurements taken exceeded the 5 mW/cm2 limit accepted by the International Radiation Protection Association and the National Council on Radiation Protection and Measurement, though none exceeded the American Conference of Governmental Industrial Hygienists, American National Standards Institute, Institute of Electrical and Electronic Engineers, or Occupational Safety and Health Administration standard of 10 mW/cm2. The four high measurements were maximum power density readings taken directly in front of the radar. Of the 812 measurements taken at the officers' seated ocular and testicular positions, none exceeded 0.04 mW/cm2; the highest of these (0.034 mW/cm2) was less than 1% of the most conservative current safety standards. High exposures in the limited region directly in front of the radar aperture are easily avoided with proper training. Results of this study indicate that police officer exposure to microwave radiation is apparently minimal. However, because of uncertainty in the medical and scientific communities concerning nonionizing radiation, it is recommended that law enforcement agencies implement a policy of prudent avoidance, including purchasing units with the lowest published maximum power densities, purchasing dash/rear deck-mounted units with antennae mounted outside the patrol vehicle, and training police officers to use the "stand-by" mode when not actually using radar. PMID:10671181

  5. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    SciTech Connect

    Tanaka, Senku, E-mail: senku@ele.kindai.ac.jp [Department of Electric and Electronic Engineering, Faculty of Science and Engineering, Kinki University, Higashiosaka 577-8502 (Japan); Otani, Tomohiro; Fukuzawa, Ken; Hiromitsu, Ichiro [Department of Physics and Materials Science, Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao [Synchrotron Light Application Center, Saga University, Saga 840-8502 (Japan)

    2014-05-12

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4?eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4?eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1?nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  6. Anomalous radon emission as precursor of earthquake

    NASA Astrophysics Data System (ADS)

    Ghosh, Dipak; Deb, Argha; Sengupta, Rosalima

    2009-10-01

    Recent years have seen an ever increasing interest in studying the usefulness of radon measurements in earth sciences. Radon emissions that are enhanced by forthcoming geophysical events as earthquakes or volcanic activity have been observed all over the world. The abnormal radon exhalation from the interior of earth, as a precursory phenomenon related to earthquakes and as an indicator of underlying geological faults, is an important field of investigation. For this purpose a number of active and passive methods for getting radon signals have been developed. Several models have been proposed as an explanation of the experimental field data. This paper gives a brief review of the progress made in the field of radon measurements in earth sciences specially in predicting earthquakes. Radon anomalies that have been observed in soil gas as well as groundwater or spring prior to earthquakes have been reviewed in this paper. The models proposed in relating precursor time, epicentral distance, magnitude of earthquake have also been discussed.

  7. Vacuum field energy and spontaneous emission in anomalously dispersive cavities

    SciTech Connect

    Bradshaw, Douglas H.; Di Rosa, Michael D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2011-05-15

    Anomalously dispersive cavities, particularly white-light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, they have been proposed for use in laser interferometer gravitational-wave observatory (LIGO)-like gravity-wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed ({h_bar}/2{pi}){omega}/2. For white-light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.

  8. Preliminary separation of galactic and cosmic microwave emission for the COBE Differential Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Bennet, C. L.; Smoot, G. F.; Hinshaw, G.; Wright, E. L.; Kogut, A.; De Amici, G.; Meyer, S. S.; Weiss, R.; Wilkinson, D. T.; Gulkis, S.

    1992-01-01

    Preliminary models of microwave emission from the Milky Way Galaxy based on COBE and other data are constructed for the purpose of distinguishing cosmic and Galactic signals. Differential Microwave Radiometer (DMR) maps, with the modeled Galactic emission removed, are fitted for a quadrupole distribution. Autocorrelation functions for individual Galactic components are presented. When Galactic emission is removed from the DMR data, the residual fluctuations are virtually unaffected, and therefore they are not dominated by any known Galactic emission component.

  9. Preliminary separation of galactic and cosmic microwave emission for the COBE Differential Microwave Radiometer

    SciTech Connect

    Bennet, C.L.; Smoot, G.F.; Hinshaw, G.; Wright, E.L.; Kogut, A.; De Amici, G.; Meyer, S.S.; Weiss, R.; Wilkinson, D.T.; Gulkis, S. (NASA, Goddard Space Flight Center, Greenbelt, MD (United States) Lawrence Berkeley Laboratory, CA (United States) California, University, Berkeley (United States) Universities Space Research Association, Boulder, CO (United States) California, University, Los Angeles (United States) MIT, Cambridge, MA (United States) Princeton University, NJ (United States) JPL, Pasadena, Ca (United States))

    1992-09-01

    Preliminary models of microwave emission from the Milky Way Galaxy based on COBE and other data are constructed for the purpose of distinguishing cosmic and Galactic signals. Differential Microwave Radiometer (DMR) maps, with the modeled Galactic emission removed, are fitted for a quadrupole distribution. Autocorrelation functions for individual Galactic components are presented. When Galactic emission is removed from the DMR data, the residual fluctuations are virtually unaffected, and therefore they are not dominated by any known Galactic emission component. 42 refs.

  10. Galactic Microwave Emission at Degree Angular Scales

    NASA Astrophysics Data System (ADS)

    de Oliveira-Costa, Angélica; Kogut, A.; Devlin, Mark J.; Netterfield, C. Barth; Page, Lyman A.; Wollack, Edward J.

    1997-06-01

    We cross-correlate the Saskatoon Ka- and Q-band cosmic microwave background (CMB) data with different maps to quantify possible foreground contamination. We detect a marginal correlation (>~2 ?) with the Diffuse Infrared Background Experiment (DIRBE) 240, 140, and 100 ?m maps, but we find no significant correlation with point sources, with the Haslam 408 MHz map, or with the Reich and Reich 1420 MHz map. The rms amplitude of the component correlated with DIRBE is about 20% of the CMB signal. Interpreting this component as free-free emission, this normalization agrees with that of the 1996 works of Kogut et al. and supports the hypothesis that the spatial correlation between dust and warm ionized gas observed on large angular scales persists to smaller angular scales. Subtracting this contribution from the CMB data reduces the normalization of the Saskatoon power spectrum by only a few percent.

  11. A microwave emissivity model of sea surface under wave breaking

    NASA Astrophysics Data System (ADS)

    Wei, En-Bo; Ge, Yong

    2005-06-01

    With the effective medium approximation theory of composites, a remedial model is proposed for estimating the microwave emissivity of sea surface under wave breaking driven by strong wind on the basis of an empirical model given by Pandey and Kakar. In our model, the effects of the shapes of seawater droplets and the thickness of whitecap layer (i.e. a composite layer of air and sea water droplets) over the sea surface on the microwave emissivity are investigated by calculating the effective dielectric constant of whitecaps layer. The wind speed is included in our model and the responses of water droplets shapes, such as sphere and ellipsoid, to the emissivity are also discussed at different microwave frequencies. The model is in good agreement with the experimental data of microwave emissivity of sea surface at microwave frequencies of 6.6, 10.7 and 37GHz.

  12. Objective Characterization of Snow Microstructure for Microwave Emission Modeling

    NASA Technical Reports Server (NTRS)

    Durand, Michael; Kim, Edward J.; Molotch, Noah P.; Margulis, Steven A.; Courville, Zoe; Malzler, Christian

    2012-01-01

    Passive microwave (PM) measurements are sensitive to the presence and quantity of snow, a fact that has long been used to monitor snowcover from space. In order to estimate total snow water equivalent (SWE) within PM footprints (on the order of approx 100 sq km), it is prerequisite to understand snow microwave emission at the point scale and how microwave radiation integrates spatially; the former is the topic of this paper. Snow microstructure is one of the fundamental controls on the propagation of microwave radiation through snow. Our goal in this study is to evaluate the prospects for driving the Microwave Emission Model of Layered Snowpacks with objective measurements of snow specific surface area to reproduce measured brightness temperatures when forced with objective measurements of snow specific surface area (S). This eliminates the need to treat the grain size as a free-fit parameter.

  13. Simulation of the microwave emission from extensive air showers

    NASA Astrophysics Data System (ADS)

    Le Coz, S.

    2014-12-01

    Ultra-high energy cosmic rays are detected through the extensive air showers they create when entering the atmosphere. The electromagnetic content of air showers is at the origin of different types of electromagnetic wave emissions, in different wavelength ranges. Air shower fluorescence light is detected routinely in ground-base detectors such as the Pierre Auger Observatory or Telescope Array. Decametric emissions (MHz) have been observed by different cosmic ray experiments equipped with antennas. Novel detection techniques based on the postulated GHz emission from molecular bremsstrahlung in air showers are also currently being studied. They are motivated by the observation of a microwave emission due to the low energy shower electrons generated by a high-energy electron beam passing through targets, in accelerator experiments. A fast simulation of this microwave emission from extensive air showers is reported here.

  14. Anomalous conductivity and secondary electron emission in Hall effect thrusters

    SciTech Connect

    Garrigues, L.; Hagelaar, G. J. M.; Boniface, C.; Boeuf, J. P. [Centre de Physique des Plasmas et Applications de Toulouse, CNRS, Universite Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 4 (France)

    2006-12-15

    This paper is devoted to the study of the effects of electron-wall interactions on cross magnetic field electron momentum and energy losses in Hall effect thrusters. By coupling a semianalytical model of the wall sheath similar to models used by several authors in this context, with a two-dimensional hybrid simulation of a Hall effect thruster, we find that the cross magnetic field conductivity enhanced by electron-wall collisions and secondary electron emission is not sufficient to explain the conductivity deduced from experiments. Calculated current-voltage curves including electron-wall collisions from a standard sheath model as the sole 'anomalous' conductivity mechanism do not reproduce the measurements, especially at high discharge voltages, and for various wall ceramics. Results also show that a one-dimensional description of electron-wall collisions with a constant radial plasma density profile as used by many authors leads to an overestimation of the contribution of electron-wall interactions to cross magnetic field conductivity.

  15. Fine and ultrafine particle emissions from microwave popcorn.

    PubMed

    Zhang, Q; Avalos, J; Zhu, Y

    2014-04-01

    This study characterized fine (PM2.5 ) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre-packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil-lined original package or a brown paper bag. UFPs and PM2.5 generated by microwaving popcorn were 150-560 and 350-800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil-lined original package with a brown paper bag significantly reduced the peak concentration by 24-87% for total particle number and 36-70% for PM2.5 . A positive relationship was observed between both UFP number and PM2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10(10) to 8.0 × 10(10) No./min for total particle number and from 134 to 249 ?g/min for PM2.5 . PMID:24106981

  16. SPINNING DUST EMISSION: EFFECTS OF IRREGULAR GRAIN SHAPE, TRANSIENT HEATING, AND COMPARISON WITH WILKINSON MICROWAVE ANISOTROPY PROBE RESULTS

    SciTech Connect

    Hoang, Thiem; Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, WI 53706 (United States); Draine, B. T. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2011-11-10

    Planck is expected to answer crucial questions on the early universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia I{sub 1} {>=} I{sub 2} {>=} I{sub 3}. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by I{sub 1}:I{sub 2}:I{sub 3}. We discuss how the orientation of the dipole moment {mu} in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of {mu} than in the case of weak thermal fluctuations. We calculate spinning dust spectra for a range of gas density and dipole moment. The effect of compressible turbulence on spinning dust emission is investigated. We show that the emission in a turbulent medium increases by a factor from 1.2 to 1.4 relative to that in a uniform medium, as the sonic Mach number M{sub s} increases from 2 to 7. Finally, spinning dust parameters are constrained by fitting our improved model to five-year Wilkinson Microwave Anisotropy Probe cross-correlation foreground spectra, for both the H{alpha}-correlated and 100-{mu}m-correlated emission spectra.

  17. Salinity effects on the microwave emission of soils

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; Oneill, Peggy E.

    1987-01-01

    Controlled plot experiments were conducted to collect L and C band passive microwave data concurrent with ground observations of salinity and soil moisture. Two dielectric mixing models were used with an emission model to predict the emissivity from a bare smooth uniform profile. The models produce nearly identical results when near zero salinity is involved and reproduce the observed data at L band extremely well. Discrepancies at C band are attributed to sampling depth problems. Comparisons of predicted emissivities at various salinities with observed values indicate that the dynamic range of the emissivities can be explained using either of the dielectric mixing models. Evaluation of the entire data set, which included four salinity levels, indicates that for general application the effects of soil salinity can be ignored in interpreting microwave data for estimating soil moisture under most agricultural conditions.

  18. Effects of salinity on the microwave emission of soils

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Oneill, P. E.

    1986-01-01

    Controlled plot experiments were conducted to collect L and C band passive microwave data concurrent with ground observations of salinity and soil moisture. Two dielectric mixing models were used with an emission model to predict the emissivity from a bare smooth uniform profile. The models produce nearly identical results when near zero salinity is involved and reproduce the observed data at L band extremely well. Discrepancies at C band are attributed to sampling depth problems. Comparisons of predicted emissivities at various salinities with observed values indicate that the dynamic range of the emissivities can be explained using either of the dielectric mixing models. Evaluation of the entire data set, which included four salinity levels, indicates that for general application the effects of soil salinity can be ignored in interpreting microwave data for estimating soil moisture under most agricultural conditions.

  19. A Parameterization of Effective Soil Temperature for Microwave Emission

    Microsoft Academic Search

    B. J. Choudhury; T. J. Schmugge; T. Mo

    1982-01-01

    The observed microwave brightness temperature of soils depends upon the soil temperature profile, which in a remote sensing application will not be known in any detail. In this paper we discuss a parameterization of effe:tive soil temperature, which when divided into the brightness temperature gives the emissivity, in terms of surface (To) and deep (T) soil temperatures as T =

  20. Long-term snowpack properties retrieval using satellite microwave emissivities

    NASA Astrophysics Data System (ADS)

    Shahroudi, Narges

    The main objective of this research is to improve the retrieval of snowpack properties using passive microwave. First part of this study shows how to better isolate the snow signature from microwave signal. The second part explains an inversion method to retrieve snowpack properties using the snow signature. The third part produces a 12-year-long time-series of seasonal snow parameters (snow depth, density, grain size, SWE) for the northern hemisphere. The microwave emissivities used in this study are derived from SSM/I passive microwave observations by removing the contributions of the cloud and atmosphere and then separating out the surface temperature. The sensitivity of the effective emissivity to the presence/absence of snow is evaluated for the Northern Hemisphere. The time-anomaly of differences between effective emissivity at 19V and 85V enabled the constant effects of land surface vegetation properties to be removed to isolate the snow signature. The snow detection in comparison with MODIS (Vis/IR) snow cover product agrees for 92% of matched locations and times. The retrieval is performed by inverting a snow emission model (Microwave Emission Model of Layerd Snowpack, MEMLS) based on neural network techniques. The model inputs (Snow properties) and the model outputs (simulated emissivities) were used to train and test the neural network. Then the surface microwave emissivities (pixels that were identified as snow), the skin temperature, and the ground emissivity (emissivities of the snow-free pixel) were used as the inputs of the neural network and to retrieve snow depth, snow density, snow grain size, and liquid water content of the snowpack. An evaluation of the methodology has been developed to assess the performance of the retrieval product on different spatial and temporal scales. The method was able to retrieve dry snow successfully. The method was able to identify wet snowpack. With the retrieved snow depth and density it was possible to estimate SWE. A comparison of snow depth and SWE with Chang algorithm showed a 0.9 correlation. In comparison with CMC the retrieved depth and SWE were higher. It was concluded that the algorithm is well able to measure dry snow depth and SWE spatially and temporally.

  1. Quantifying Uncertainties in Land-Surface Microwave Emissivity Retrievals

    NASA Technical Reports Server (NTRS)

    Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Prigent, Catherine; Norouzi, Hamidreza; Aires, Filipe; Boukabara, Sid-Ahmed; Furuzawa, Fumie A.; Masunaga, Hirohiko

    2013-01-01

    Uncertainties in the retrievals of microwaveland-surface emissivities are quantified over two types of land surfaces: desert and tropical rainforest. Retrievals from satellite-based microwave imagers, including the Special Sensor Microwave Imager, the Tropical Rainfall Measuring Mission Microwave Imager, and the Advanced Microwave Scanning Radiometer for Earth Observing System, are studied. Our results show that there are considerable differences between the retrievals from different sensors and from different groups over these two land-surface types. In addition, the mean emissivity values show different spectral behavior across the frequencies. With the true emissivity assumed largely constant over both of the two sites throughout the study period, the differences are largely attributed to the systematic and random errors inthe retrievals. Generally, these retrievals tend to agree better at lower frequencies than at higher ones, with systematic differences ranging 1%-4% (3-12 K) over desert and 1%-7% (3-20 K) over rainforest. The random errors within each retrieval dataset are in the range of 0.5%-2% (2-6 K). In particular, at 85.5/89.0 GHz, there are very large differences between the different retrieval datasets, and within each retrieval dataset itself. Further investigation reveals that these differences are most likely caused by rain/cloud contamination, which can lead to random errors up to 10-17 K under the most severe conditions.

  2. Imaging spectroscopy of solar microwave radiation. 1: Flaring emission

    NASA Technical Reports Server (NTRS)

    Lim, Jeremy; Gary, Dale E.; Hurford, Gordon J.; Lemen, James R.

    1994-01-01

    We present observations of an impulsive microwave burst on the Sun with both high spatial and spectral resolution, made with the Solar Array at the Owens Valley Radio Observatory (OVRO). We used the measured brightness temperature spectrum to infer the emission process responsible for each microwave source, and to derive physical conditions in the source region. We confimed our predictions using soft X-ray measurements from Geostationary Operational Environmental Satellite (GOES), soft X-ray images from Yohkoh, and H-alpha flare images together with sunspots and magnetogram images from the Big Bear Solar Observatory.

  3. Modeling galactic microwave emission from 0. 4 to 50 GHz

    SciTech Connect

    Witebsky, C.; Smoot, G.F.; De Amici, G.; Aymon, J. (Lawrence Berkeley Laboratory and Space Sciences Laboratory, University of California, Berkeley (United States))

    1992-06-25

    We have developed a full-sky model of galactic microwave radiation at frequencies from 0.4 GHz to [gt]50 GHz, with a resolution of [similar to]2[degree]. The primary components are free-free emission from ionized hydrogen and synchrotron emission from cosmic rays. (Dust emission is negligible in this frequency range.) A variety of data are used to estimate free-free emission from HII: the galactic plane and adjacent regions come from continuum surveys near 2.7 GHz; emission at higher galactic latitudes is approximated by a cosecant law. The synchrotron component is extrapolated from sky-survey data at 408 MHz. Both components vary with frequency. This model has been used to derive corrections for galactic emission in our measurements of the low-frequency CMBR spectrum.

  4. Laboratory polarimetric measurements of microwave emission from capillary waves

    NASA Astrophysics Data System (ADS)

    Trokhimovski, Y. G.; Kuzmin, A. V.; Pospelov, M. N.; Irisov, V. G.; Sadovsky, I. N.

    2003-06-01

    The results of polarimetric microwave measurements of thermal emission from a water surface with artificial periodic structure are presented. The goal of the experiment is to verify the results of a model describing polarized microwave emission from gravity-capillary waves on a sea surface. Periodic undulations of water surface were produced in a tank by a set of parallel nylon threads raised slightly above the mean surface. Due to surface tension, the water surface assumes a periodic profile; the amplitude of the roughness was changed by moving the frame with the threads up and down. The measurements of the three Stokes parameters of the emission were carried out with the Ka-band polarimeter. The experimental setup allowed measurements to be made over a wide range of view angles (from near-nadir to 70°). The tank rotation allowed variation of the azimuthal angle between the periodic structure and the observation plane of more than 300°. The experimental data show the existence of the resonant peak in the Stokes parameters predicted by the model. The amplitude of the peak reached 10 K. Also, drastic contrasts were registered in the azimuth dependencies of the Stokes parameters. This result is evidence of the important role that short gravity-capillary waves play in sea-surface polarized microwave emission.

  5. Experimental study of the microwave emission from electrons in air

    E-print Network

    E. Conti; G. Collazuol; G. Sartori

    2014-09-26

    We searched for the emission of microwave radiation in the Ku band generated by a 95 keV electron beam in air. We unequivocally detected the radiation, and measured its yield and angular dependence. Both the emitted power and its angular pattern are well described by a model, where microwave photons are generated via bremsstrahlung in the free-electron atomic-nucleus collisions, during the slowdown of the electrons. As a consequence, the radiation is not isotropic but peaked in the forward direction. The emission yield scales proportionally with the number of electrons. This contrasts a previous claim that the yield scales with the number squared, due to coherence. With a Monte Carlo simulation we extrapolate our results to the Ultra High Energy Cosmic Ray energy range.

  6. HARD X-RAY AND MICROWAVE EMISSIONS FROM SOLAR FLARES WITH HARD SPECTRAL INDICES

    SciTech Connect

    Kawate, T. [Kwasan and Hida Observatory, Kitashirakawa-oiwakecho, Sakyo, Kyoto 606-8502 (Japan); Nishizuka, N. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 229-8510 (Japan); Oi, A. [College of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan); Ohyama, M. [Faculty of Education, Shiga University, 2-5-1 Hiratsu, Otsu, Shiga 1-1, Baba Hikone city, Siga 522-8522 (Japan); Nakajima, H., E-mail: kawate@kusastro.kyoto-u.ac.jp [Nobeyama Solar Radio Observatory, NAOJ, Nobeyama, Minamisaku, Nagano 384-1305 (Japan)

    2012-03-10

    We analyze 10 flare events that radiate intense hard X-ray (HXR) emission with significant photons over 300 keV to verify that the electrons that have a common origin of acceleration mechanism and energy power-law distribution with solar flares emit HXRs and microwaves. Most of these events have the following characteristics. HXRs emanate from the footpoints of flare loops, while microwaves emanate from the tops of flare loops. The time profiles of the microwave emission show delays of peak with respect to those of the corresponding HXR emission. The spectral indices of microwave emissions show gradual hardening in all events, while the spectral indices of the corresponding HXR emissions are roughly constant in most of the events, though rather rapid hardening is simultaneously observed in some for both indices during the onset time and the peak time. These characteristics suggest that the microwave emission emanates from the trapped electrons. Then, taking into account the role of the trapping of electrons for the microwave emission, we compare the observed microwave spectra with the model spectra calculated by a gyrosynchrotron code. As a result, we successfully reproduce the eight microwave spectra. From this result, we conclude that the electrons that have a common acceleration and a common energy distribution with solar flares emit both HXR and microwave emissions in the eight events, though microwave emission is contributed to by electrons with much higher energy than HXR emission.

  7. Observations of Microwave Continuum Emission from Air Shower Plasmas

    E-print Network

    P. W. Gorham; N. G. Lehtinen; G. S. Varner; J. J. Beatty; A. Connolly; P. Chen; M. E. Conde; W. Gai; C. Hast; C. L. Hebert; C. Miki; R. Konecny; J. Kowalski; J. Ng; J. G. Power; K. Reil; D. Saltzberg; B. T. Stokes; D. Walz

    2007-05-17

    We investigate a possible new technique for microwave measurements of ultra-high energy cosmic ray (UHECR) extensive air showers which relies on detection of expected continuum radiation in the microwave range, caused by free-electron collisions with neutrals in the tenuous plasma left after the passage of the shower. We performed an initial experiment at the AWA (Argonne Wakefield Accelerator) laboratory in 2003 and measured broadband microwave emission from air ionized via high energy electrons and photons. A follow-up experiment at SLAC (Stanford Linear Accelerator Center) in summer of 2004 confirmed the major features of the previous AWA observations with better precision and made additional measurements relevant to the calorimetric capabilities of the method. Prompted by these results we built a prototype detector using satellite television technology, and have made measurements indicating possible detection of cosmic ray extensive air showers. The method, if confirmed by experiments now in progress, could provide a high-duty cycle complement to current nitrogen fluorescence observations of UHECR, which are limited to dark, clear nights. By contrast, decimeter microwave observations can be made both night and day, in clear or cloudy weather, or even in the presence of moderate precipitation.

  8. Anomalous Biophoton Emission during Germination Process of Red Bean

    NASA Astrophysics Data System (ADS)

    Kai, Shoichi; Mitani, Tomohiko; Fujikawa, Masahiro

    1993-03-01

    Spontaneous biophoton emission was investigated for the germination and the growth process of a red bean seed. The growth process of the root of a red bean after germination was statistically investigated for a total of 2000 seeds whose average root growth dynamics was well described by a simple logistic equation. Strong biophoton emission was observed at two inflection points of the logistic curve. Namely, when maximum acceleration of the root growth occurred, maximum biophoton emission was observed.

  9. Quantifying Uncertainties in Land Surface Microwave Emissivity Retrievals

    NASA Technical Reports Server (NTRS)

    Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Prigent, Catherine; Norouzi, Hamidreza; Aires, Filipe; Boukabara, Sid-Ahmed; Furuzawa, Fumie A.; Masunaga, Hirohiko

    2012-01-01

    Uncertainties in the retrievals of microwave land surface emissivities were quantified over two types of land surfaces: desert and tropical rainforest. Retrievals from satellite-based microwave imagers, including SSM/I, TMI and AMSR-E, were studied. Our results show that there are considerable differences between the retrievals from different sensors and from different groups over these two land surface types. In addition, the mean emissivity values show different spectral behavior across the frequencies. With the true emissivity assumed largely constant over both of the two sites throughout the study period, the differences are largely attributed to the systematic and random errors in the retrievals. Generally these retrievals tend to agree better at lower frequencies than at higher ones, with systematic differences ranging 14% (312 K) over desert and 17% (320 K) over rainforest. The random errors within each retrieval dataset are in the range of 0.52% (26 K). In particular, at 85.0/89.0 GHz, there are very large differences between the different retrieval datasets, and within each retrieval dataset itself. Further investigation reveals that these differences are mostly likely caused by rain/cloud contamination, which can lead to random errors up to 1017 K under the most severe conditions.

  10. Directional emissions achieved with anomalous reflection phases of metamaterials

    Microsoft Academic Search

    Kun Ding; Tao Jiang; Jiaming Hao; Lixin Ran; Lei Zhou

    2010-01-01

    For a small antenna placed on a metamaterial ground plane vertically or horizontally, we analyzed the conditions under which the antenna emissions are highly directional. We found through finite-difference time-domain (FDTD) simulations that a previously discovered directional emission phenomenon can be explained by our theory for the horizontal antenna case. For the vertical antenna case, we employed FDTD simulations to

  11. High reflection emission assisted by phase compensation via anomalous dispersion

    E-print Network

    Hai-Tao Zhou; Miao-jun Guo; Da-Wei Wang; Jun-Xiang Zhang; Shi-Yao Zhu

    2011-02-23

    The reflection spectrum of a probe light in a -type three-level atomic system coupled by an off-resonant standing-wave is investigated experimentally and theoretically. We show that the maximum value of reflection coefficient occurs when both of the coupling and probe lights are tuned off resonances from the atomic transitions. The nature of enhanced reflection is attributed to the phase compensation caused by the anomalous dispersion, which leads to a significant reduction of nonlinear phase mismatch in atomic four-wave mixing. At certain detuning of coupling and probe frequencies near two-photon resonance, there exits a best compensation, so the reflection efficiency reaches its maximum. The dependences of efficiency on the intensity of coupling fields and the density of atoms are also studied.

  12. Investigating Non-icy Material Fraction from Microwave Emission

    NASA Astrophysics Data System (ADS)

    Zhang, Zhimeng; Hayes, Alex; Janssen, Mike; Nicholson, Phillip; Cuzzi, Jeff; Dunn, David; de Pater, Imke

    2014-11-01

    We will present calibrated, high- 2000 km) and low- 8000 km) resolution maps of Saturn’s rings at 2.2-cm wavelength acquired by the Cassini radar radiometer. Microwave emission is the ideal waveband for studying the scattering properties of cm-scale ring particles and for constraining the thermal emission from (possibly buried) non-icy ring contaminants, which, unlike water ice, behave as blackbodies at cm-wavelengths. While occultation observations are necessarily restricted to near-forward scattered light, scattered emission from Saturn (an extended source) can be viewed at a wide range of geometries. In order to successfully remove energy contributed by radar’s extensive side-lobes, we use an iterative self-calibration process. The current calibration reaches an RMS residual of 0.18 K 2% ring brightness temperature). The observed microwave brightness temperature of Saturn’s rings is dominated by scattered Saturn emission and intrinsic thermal emission from the rings. We adopted a Monte Carlo multiple scattering model for the A, B and C rings that treats non-icy materials as inclusions in icy particles. Our results predict that the non-icy component of the C ring, assuming that contaminants behave with the dielectric properties of acidic rock, has a baseline volume fraction of ~2% throughout the entire C Ring with humps at the center and inner region that reach a maximum of ~7%. The implications of these results for the origin and evolution of the Saturn’s rings will be discussed. Furthermore, in optically thick B ring, the scattering properties of ring particles are altered by the closely packed effect. We employed a near-field Fresnel diffraction pattern for near field scattering events. Details on this near-field effect will be discussed.

  13. Subsurface Emission Effects in AMSR-E Measurements: Implications for Land Surface Microwave Emissivity Retrieval

    NASA Technical Reports Server (NTRS)

    Galantowicz, John F.; Moncet, Jean-Luc; Liang, Pan; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    An analysis of land surface microwave emission time series shows that the characteristic diurnal signature associated with subsurface emission in sandy deserts carry over to arid and semi-arid region worldwide. Prior work found that diurnal variation of Special Sensor Microwave/Imager (SSM/I) brightness temperatures in deserts was small relative to International Satellite Cloud Climatology Project land surface temperature (LST) variation and that the difference varied with surface type and was largest in sand sea regions. Here we find more widespread subsurface emission effects in Advanced Microwave Scanning Radiometer-EOS (AMSR-E) measurements. The AMSR-E orbit has equator crossing times near 01:30 and 13 :30 local time, resulting in sampling when near-surface temperature gradients are likely to be large and amplifying the influence of emission depth on effective emitting temperature relative to other factors. AMSR-E measurements are also temporally coincident with Moderate Resolution Imaging Spectroradiometer (MODIS) LST measurements, eliminating time lag as a source of LST uncertainty and reducing LST errors due to undetected clouds. This paper presents monthly global emissivity and emission depth index retrievals for 2003 at 11, 19, 37, and 89 GHz from AMSR-E, MODIS, and SSM/I time series data. Retrieval model fit error, stability, self-consistency, and land surface modeling results provide evidence for the validity of the subsurface emission hypothesis and the retrieval approach. An analysis of emission depth index, emissivity, precipitation, and vegetation index seasonal trends in northern and southern Africa suggests that changes in the emission depth index may be tied to changes in land surface moisture and vegetation conditions

  14. Effect of soil texture on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.

    1980-01-01

    The intensity brightness temperature of the microwave emission from the soil is determined primarily by its dielectric properties. The large difference between the dielectric constant of water and that of dry soil produces a strong dependence of the soil's dielectric constant on its moisture content. This dependence is effected by the texture of the soil because the water molecules close to the particle surface are tightly bound and do not contribute significantly to the dielectric properties. Since this surface area is a function of the particle size distribution (soil texture), being larger for clay soils with small particles, and smaller for sandy soils with larger particles; the dielectric properties will depend on soil texture. Laboratory measurements of the dielectric constant for soils are summarized. The dependence of the microwave emission on texture is demonstrated by measurements of brightness temperature from an aircraft platform for a wide range of soil textures. It is concluded that the effect of soil texture differences on the observed values can be normalized by expressing the soil moisture values as a percent field capacity for the soil.

  15. SLOW MAGNETOACOUSTIC OSCILLATIONS IN THE MICROWAVE EMISSION OF SOLAR FLARES

    SciTech Connect

    Kim, S.; Shibasaki, K. [Nobeyama Solar Radio Observatory/NAOJ, Nagano 384-1305 (Japan); Nakariakov, V. M., E-mail: sjkim@nro.nao.ac.jp [Physics Department, University of Warwick, Coventry, CV4 7AL (United Kingdom)

    2012-09-10

    Analysis of the microwave data, obtained in the 17 GHz channel of the Nobeyama Radioheliograph during the M1.6 flare on 2010 November 4, revealed the presence of 12.6 minute oscillations of the emitting plasma density. The oscillations decayed with the characteristic time of about 15 minutes. Similar oscillations with the period of about 13.8 minutes and the decay time of 25 minutes are also detected in the variation of EUV emission intensity measured in the 335 A channel of the Solar Dynamics Observatory/Atmospheric Imaging Assembly. The observed properties of the oscillations are consistent with the oscillations of hot loops observed by the Solar and Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation (SUMER) in the EUV spectra in the form of periodic Doppler shift. Our analysis presents the first direct observations of the slow magnetoacoustic oscillations in the microwave emission of a solar flare, complementing accepted interpretations of SUMER hot loop oscillations as standing slow magnetoacoustic waves.

  16. First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Emission

    NASA Technical Reports Server (NTRS)

    Bennett, C. L.; Hill, R. S.; Hinshaw, G.; Nolta, M. R.; Odegard, N.; Page, L.; Spergel, D. N.; Weiland, J. L.; Wright, E. L.; Halpern, M.

    2003-01-01

    The WMAP mission has mapped the full sky to determine the geometry, content, and evolution of the universe. Full sky maps are made in five microwave frequency bands to separate the temperature anisotropy of the cosmic microwave background (CMB) from foreground emission, including diffuse Galactic emission and Galactic and extragalactic point sources. We define masks that excise regions of high foreground emission, so CMB analyses can became out with minimal foreground contamination. We also present maps and spectra of the individual emission components, leading to an improved understanding of Galactic astrophysical processes. The effectiveness of template fits to remove foreground emission from the WMAP data is also examined. These efforts result in a CMB map with minimal contamination and a demonstration that the WMAP CMB power spectrum is insensitive to residual foreground emission. We use a Maximum Entropy Method to construct a model of the Galactic emission components. The observed total Galactic emission matches the model to less than 1% and the individual model components are accurate to a few percent. We find that the Milky Way resembles other normal spiral galaxies between 408 MHz and 23 GHz, with a synchrotron spectral index that is flattest (beta(sub s) approx. -2.5) near star-forming regions, especially in the plane, and steepest (beta(sub s) approx. -3) in the halo. This is consistent with a picture of relativistic cosmic ray electron generation in star-forming regions and diffusion and convection within the plane. The significant synchrotron index steepening out of the plane suggests a diffusion process in which the halo electrons are trapped in the Galactic potential long enough to suffer synchrotron and inverse Compton energy losses and hence a spectral steepening. The synchrotron index is steeper in the WMAP bands than in lower frequency radio surveys, with a spectral break near 20 GHz to beta(sub s) less than -3. The modeled thermal dust spectral index is also steep in the WMAP bands, with beta(sub d) approx. = 2.2. Our model is driven to these conclusions by the low level of total foreground contamination at approx. 60 GHz. Microwave and Ha measurements of the ionized gas agree well with one another at about the expected levels. Spinning dust emission is limited to less than 5% of the Ka-band foreground emission. A catalog of 208 point sources is presented. The reliability of the catalog is 98%, i.e., we expect five of the 208 sources to be statistically spurious. The mean spectral index of the point sources is alpha approx. 0(beta approx. -2). Derived source counts suggest a contribution to the anisotropy power from unresolved sources of (15.0 +/- 1.4) x 10(exp -3)micro sq K sr at Q-band and negligible levels at V-band and W-band. The Sunyaev-Zeldovich effect is shown to be a negligible "contamination" to the maps.

  17. Microwave emission at high Galactic latitudes in the four-year DMRsky maps

    SciTech Connect

    Kogut, A.; Banday, A.J.; Bennett, C.L.; Gorski, K.M.; Hinshaw,G.; Smoot, G.F.; Wright, E.L.

    1996-01-10

    We use the COBE(8) Differential Microwave Radiometers (DMR)4 yr sky maps to model Galactic microwave emission at high latitudes (/b/>20 degrees). Cross-correlation of the DMR maps with Galactic template maps detects fluctuations in the high-latitude microwave sky brightness with the angular variation of the DIRBE far-infrared dust maps and a frequency dependence consistent with a superposition of dust and free-free emission. We find no significant correlations between the DMR maps and various synchrotron templates. On the largest angular scales (e.g., quadrupole), Galactic emission is comparable in amplitude to the anisotropy in the cosmic microwave background (CMB). The CMB quadrupole amplitude, after correction for Galactic emission, has amplitude Q(rms) =10.7 mu K with random uncertainty 3.6 mu K and systematic uncertainty 7.1mu K from uncertainty in our knowledge of Galactic microwave emission.

  18. First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers.

    PubMed

    Smída, R; Werner, F; Engel, R; Arteaga-Velázquez, J C; Bekk, K; Bertaina, M; Blümer, J; Bozdog, H; Brancus, I M; Chiavassa, A; Cossavella, F; Di Pierro, F; Doll, P; Fuchs, B; Fuhrmann, D; Grupen, C; Haungs, A; Heck, D; Hörandel, J R; Huber, D; Huege, T; Kampert, K-H; Kang, D; Klages, H; Kleifges, M; Krömer, O; Link, K; Luczak, P; Ludwig, M; Mathes, H J; Mathys, S; Mayer, H J; Melissas, M; Morello, C; Neunteufel, P; Oehlschläger, J; Palmieri, N; Pekala, J; Pierog, T; Rautenberg, J; Rebel, H; Riegel, M; Roth, M; Salamida, F; Schieler, H; Schoo, S; Schröder, F G; Sima, O; Stasielak, J; Toma, G; Trinchero, G C; Unger, M; Weber, M; Weindl, A; Wilczy?ski, H; Will, M; Wochele, J; Zabierowski, J

    2014-11-28

    We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the Cosmic-Ray Observation via Microwave Emission experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3×10^{16}??eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarized emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at E?10^{17}??eV. PMID:25494064

  19. Theoretical models of free-free microwave emission from solar magnetic loops

    NASA Technical Reports Server (NTRS)

    Brosius, Jeffrey W.; Holman, Gordon D.

    1986-01-01

    The free-free microwave emission is calculated from a series of model magnetic loops. The loops are surrounded by a cooler external plasma, as required by recent simultaneous X ray and microwave observations, and a narrow transition zone separating the loops from the external plasma. To be consistent with the observational results, upper limits on the density and temperature scale lengths in the transition zone are found to be 360 km and 250 km, respectively. The models which best produce agreement with X ray and microwave observations also yielded emission measure curves which agree well with observational emission measure curves for solar active regions.

  20. Theoretical models of free-free microwave emission from solar magnetic loops

    NASA Technical Reports Server (NTRS)

    Brosius, Jeffrey W.; Holman, Gordon D.

    1988-01-01

    The free-free microwave emission is calculated from a series of model magnetic loops. The loops are surrounded by a cooler external plasma, as required by recent simultaneous X ray and microwave observations, and a narrow transition zone separating the loops from the external plasma. To be consistent with the observational results, upper limits on the density and temperature scale lengths in the transition zone are found to be 360 km and 250 km, respectively. The models which best produce agreement with X-ray and microwave observations also yielded emission measure curves which agree well with observational emission measure curves for solar active regions.

  1. Anomalous impedance of a superconductor in the resistive state caused by microwave irradiation

    SciTech Connect

    Tolpygo, S.K.; Tulin, V.A.

    1980-10-05

    The frequency dependence of the impedance of a thin superconducting film in the resistive state, which is produced by microwave irradiation, was investigated. It is shown that at frequencies f< or approx. =300 MHz the impedance of the resistive state exceeds that of the normal state.

  2. Coherent microwave emission from a solid state plasma in a high magnetic field

    NASA Astrophysics Data System (ADS)

    Kamakura, Katsutoshi

    1979-04-01

    Continuous coherent microwave emission is observed from very thin and short samples of n-InSb in high electric and high magnetic fields at 77 K. The observed frequency is determined by the sample length and applied magnetic field. It is clarified that a half-wave-length of microwave computed from the dispersion equation is equal to the sample length.

  3. Anomalous Emissions of Sulfur Dioxide and Seismicity of San Miguel Volcano, EL Salvador in October, 2006

    NASA Astrophysics Data System (ADS)

    Olmos, R.; Barahona, F.; Hernández, A.; Cartagena, R.; Henríquez, B.; López, D.; Cárdenas, C.; Galle, B.

    2007-12-01

    San Miguel (also known as Chaparrastique) volcano in eastern El Salvador is located 15 km southwest of the city of San Miguel. This volcano has erupted more than 30 times since 1699, with the last gas and ash emission on January 16, 2002. During 2006, San Miguel presented anomalous gas emissions and seismicity. In this work, the seismic parameters reported by SNET (Servicio Nacional de Estudios Territoriales de El Salvador) and the crater gas emissions measured by researchers of the University of El Salvador are compared. For the gas efflux, two types of measurements were done using the Mini-DOAS system (Galle et al., 2002): transects around the crater perimeter (~100 m) and transects following roads located between 5 and 10 km from the crater. Several measurements between October 2005 and May 2006 indicate that the sulfur dioxide efflux during quiet periods is around 20 ton/day. From May to June 2006, a progressive increase in fumarolic activity and noise from gas emissions were observed. From May to August 2006, the sulfur dioxide emissions increased to 60 ton/day. A seismic crisis started on October 9, 2006, increasing the RSAM from 10-20 to 208 on October 10, 2006. During this time, the sulfur dioxide efflux reached a maximum of 492 ton/day. This increase in sulfur dioxide efflux represents 25 times the basic emissions during the previous quiet period and 8 times the values observed from May to August 2006. The correlation coefficient between sulfur dioxide efflux and RSAM values during this period of time was 0.81, which is statistically significant at a level higher than 99.9% . These anomalous changes in seismicity and sulfur dioxide emissions at San Miguel volcano suggest a magmatic reactivation with an increase in the exsolution of magma volatiles, long period seismic events, and volcanic tremor.

  4. On the Extended Emission of the Anomalous X-ray Pulsar IE 1547.0-5408

    NASA Technical Reports Server (NTRS)

    Olausen, S. A.; Kaspi, V. M.; Ng, C. -Y.; Zhu, W. W.; Gavriil, F. P.; Woods, P. M.

    2012-01-01

    We present an analysis of the extended emission around the anomalous X-ray pulsar IE 1547.0-5408 using four XMM-Newton observations taken with the source in varying states of outburst as well as in quiescence. We find that the extended emission flux is highly variable and strongly correlated with the flux of the magnetar. Based on this result, as well as on spectral and energetic considerations, we conclude that the extended emission is dominated by a dust-scattering halo and not a pulsar wind nebula (P-VVN), as has been previously argued. We obtain an upper limit on the 2-10 keV flux of a possible PWN of 4.7 x 10(exp -14) erg/s/sq cm, three times less than the previously claimed value, implying an efficiency for conversion of spin-down energy into nebular luminosity of <9 x 10(exp -4) .

  5. Planck intermediate results. XVII. Emission of dust in the diffuse interstellar medium from the far-infrared to microwave frequencies

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Abergel, A.; Ade, P. A. R.; Aghanim, N.; Alves, M. I. R.; Aniano, G.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bonaldi, A.; Bond, J. R.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Crill, B. P.; Cuttaia, F.; Danese, L.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Joncas, G.; Jones, A.; Jones, W. C.; Juvela, M.; Kalberla, P.; Keihänen, E.; Kerp, J.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Spencer, L. D.; Starck, J.-L.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Verstraete, L.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Winkel, B.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-06-01

    The dust-Hi correlation is used to characterize the emission properties of dust in the diffuse interstellar medium (ISM) from far infrared wavelengths to microwave frequencies. The field of this investigation encompasses the part of the southern sky best suited to study the cosmic infrared and microwave backgrounds. We cross-correlate sky maps from Planck, the Wilkinson Microwave Anisotropy Probe (WMAP), and the diffuse infrared background experiment (DIRBE), at 17 frequencies from 23 to 3000 GHz, with the Parkes survey of the 21 cm line emission of neutral atomic hydrogen, over a contiguous area of 7500 deg2 centred on the southern Galactic pole. We present a general methodology to study the dust-Hi correlation over the sky, including simulations to quantify uncertainties. Our analysis yields four specific results. (1) We map the temperature, submillimetre emissivity, and opacity of the dust per H-atom. The dust temperature is observed to be anti-correlated with the dust emissivity and opacity. We interpret this result as evidence of dust evolution within the diffuse ISM. The mean dust opacity is measured to be (7.1 ± 0.6) × 10-27 cm2 H-1 × (?/ 353 GHz)1.53 ± 0.03 for 100 ? ? ? 353 GHz. This is a reference value to estimate hydrogen column densities from dust emission at submillimetre and millimetre wavelengths. (2) We map the spectral index ?mm of dust emission at millimetre wavelengths (defined here as ? ? 353 GHz), and find it to be remarkably constant at ?mm = 1.51 ± 0.13. We compare it with the far infrared spectral index ?FIR derived from greybody fits at higher frequencies, and find a systematic difference, ?mm - ?FIR = - 0.15, which suggests that the dust spectral energy distribution (SED) flattens at ? ? 353 GHz. (3) We present spectral fits of the microwave emission correlated with Hi from 23 to 353 GHz, which separate dust and anomalous microwave emission (AME). We show that the flattening of the dust SED can be accounted for with an additional component with a blackbody spectrum. This additional component, which accounts for (26 ± 6)% of the dust emission at 100 GHz, could represent magnetic dipole emission. Alternatively, it could account for an increasing contribution of carbon dust, or a flattening of the emissivity of amorphous silicates, at millimetre wavelengths. These interpretations make different predictions for the dust polarization SED. (4) We analyse the residuals of the dust-Hi correlation. We identify a Galactic contribution to these residuals, which we model with variations of the dust emissivity on angular scales smaller than that of our correlation analysis. This model of the residuals is used to quantify uncertainties of the CIB power spectrum in a companion Planck paper. Appendices are available in electronic form at http://www.aanda.org

  6. Electron-cyclotron maser and solar microwave millisecond spike emission

    NASA Technical Reports Server (NTRS)

    Li, Hong-Wei; Li, Chun-Sheng; Fu, Qi-Jun

    1986-01-01

    An intense solar microwave millisecond spike emission (SMMSE) event was observed on May 16, 1981 by Zhao and Jin at Beijing Observatory. The peak flux density of the spikes is high to 5 x 100,000 s.f.u. and the corresponding brightness temperature (BT) reaches approx. 10 to the 15th K. In order to explain the observed properties of SMMSE, it is proposed that a beam of electrons with energy of tens KeV injected from the acceleration region downwards into an emerging magnetic arch forms so-called hollow beam distribution and causes electron-cyclotron maser (ECM) instability. The growth rate of second harmonic X-mode is calculated and its change with time is deduced. It is shown that the saturation time of ECM is t sub s approx. equals 0.42 ms and only at last short stage (delta t less than 0.2 t sub s) the growth rate decreases to zero rather rapidly. So a SMMSE with very high BT will be produced if the ratio of number density of nonthermal electrons to that of background electrons, n sub s/n sub e, is larger than 4 x .00001.

  7. Land surface characterization using microwave emissivity derived from multi-satellite radiometric observations

    NASA Astrophysics Data System (ADS)

    Raju C, Suresh; Krishna Moorthy, K.; Antony, Tinu; Mathew, Nizy

    The microwave land surface emissivity has been estimated on a global scale from SSM/I brightness temperature observations at 19, 37, and 85 GHz for both horizontal (H) and vertical (V) polarizations using an in-house developed microwave Radiative Transfer computation code. The retrieval technique has been validated by comparing the retrieved emissivity with TELSEM emissivity climatology and with theoretical models. The variability in microwave emissivity with respect to geographical patterns, vegetation cover, flooded areas, and snow cover for different seasons (and interannual) have been studied. The standard deviation of the monthly mean emissivity has been found to be < 0.015 for all surface classes, except for coastal and desert regions (< 0.02). Attempt has also been made to explore the potential of microwave emissivity data for delineating flood-inundated regions as well as studying different arid and desert regions on global basis. The microwave emissivity derived from TRMM/TMI at 19.35 and 85.5 GHz with both H and V polarisations, are used for deriving the flood index parameter. The study has also been applied to the data (limited) rom MADRAS payload aboard Megha-Tropiques satellite. The estimated emissivities contribute to the data set which can be directly used for data assimilation, as an a priori input for the retrieval of atmospheric parameters over the continental region, for delineation of the flood extent, and for the characterization of arid and desert regions. The methodology and the results will be presented in detail.

  8. Characterization of Different Land Classes and Disaster Monitoring Using Microwave Land Emissivity for the Indian Subcontinent

    NASA Astrophysics Data System (ADS)

    Saha, Korak; Raju, Suresh; Antony, Tinu; Krishna Moorthy, K.

    Despite the ability of satellite borne microwave radiometers to measure the atmospheric pa-rameters, liquid water and the microphysical properties of clouds, they have serious limitations over the land owing its large and spatially heterogeneous emissivity compared to the relatively low and homogenous oceans. This calls for determination of the spatial maps of land-surface emissivity with accuracies better than ˜2%. In this study, the characterization of microwave emissivity of different land surface classes over the Indian region is carried out with the forth-coming Indo-French microwave satellite program Megha-Tropiques in focus. The land emissivity is retrieved using satellite microwave radiometer data from Special Sensor Microwave/Imager (SSM/I) and TRMM Microwave Imager (TMI) at 10, 19, 22, 37 and 85 GHz. After identify-ing the clear sky daily data, the microwave radiative transfer computation, is applied to the respective daily atmospheric profile for deducing the upwelling and downwelling atmospheric radiations. This, along with the skin temperature data, is used to retrieve land emission from satellites data. The emissivity maps of placecountry-regionIndia for three months representing winter (January) and post-monsoon (September-October) seasons of 2008 at V and H polar-izations of all the channels (except for 22 GHz) are generated. Though the land emissivity values in V-polarization vary between 0.5 and ˜1, some land surface classes such as the desert region, marshy land, fresh snow covered region and evergreen forest region, etc, show distinct emissivity characteristics. On this basis few typical classes having uniform physical properties over sufficient area are identified. Usually the Indian desert region is dry and shows low emis-sivity (˜0.88 in H-polarisation) and high polarization difference, V-H (˜0.1). Densely vegetated zones of tropical rain forests exhibit high emissivity values (˜0.95) and low polarization dif-ference (lt;0.01). The mangrove forest region and marshy areas exhibit very low emissivities (˜0.8) with very high polarization difference (˜0.2). The usefulness of microwave emissivity to identify and quantify natural disasters such as the inundated regions in the vast Ganga basin during the severe floods in 2008 over country-regionIndia and placecountry-regionBangladesh is also demonstrated as a case study Keywords: Land surface emissivity, Microwave Remote sensing, Megha-Tropiques, Disaster monitoring *corresponding author: koraksaha@gmail.com

  9. Frequency agile microwave photonic notch filter with anomalously high stopband rejection

    NASA Astrophysics Data System (ADS)

    Marpaung, David; Morrison, Blair; Pant, Ravi; Eggleton, Benjamin J.

    2013-11-01

    We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (> 60 dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This record performance is enabled by a new concept of sidebands amplitude and phase controls using an electro-optic modulator and an optical filter. This new concept enables energy efficient operation in active MWP notch filters, and opens up the pathway to enable low-power nanophotonic devices as high performance RF filters.

  10. Frequency agile microwave photonic notch filter with anomalously-high stopband rejection

    E-print Network

    Marpaung, David; Pant, Ravi; Eggleton, Benjamin J

    2013-01-01

    We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (> 60 dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This record performance is enabled by a new concept of sidebands amplitude and phase controls using an electro-optic modulator and an optical filter. This new concept enables energy efficient operation in active MWP notch filters, and opens up the pathway to enable low-power nanophotonic devices as high performance RF filters.

  11. The construction and application of the AMSR-E global microwave emissivity database

    NASA Astrophysics Data System (ADS)

    Lijuan, Shi; Yubao, Qiu; Jingjing, Niu; Wenbo, Wu

    2014-03-01

    Land surface microwave emissivity is an important parameter to describe the characteristics of terrestrial microwave radiation, and is the necessary input amount for inversion various geophysical parameters. We use brightness temperature of the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and synchronous land surface temperature and atmospheric temperature-humidity profile data obtained from the MODIS which aboard on satellite AQUA the same as AMSR-E, to retrieved microwave emissivity under clear sky conditions. After quality control, evaluation and design, the global microwave emissivity database of AMSR-E under clear sky conditions is established. This database include 2002-2011 years, different regions, different surface coverage, dual-polarized, 6.9,10.65, 18.7, 23.8, 36.5 and 89GHz, ascending and descending orbit, spatial resolution 25km, global 0.05 degrees, instantaneous and half-month averaged emissivity data. The database can provide the underlying surface information for precipitation algorithm, water-vapor algorithm, and long-resolution mode model (General Circulation Model (GCM) etc.). It also provides underlying surface information for the satellite simulator, and provides basic prior knowledge of land surface radiation for future satellite sensors design. The emissivity database or the fast emissivity obtained can get ready for climate model, energy balance, data assimilation, geophysical model simulation, inversion and estimates of the physical parameters under the cloud cover conditions.

  12. A new radiation balance microwave thermograph for simultaneous and independent temperature and emissivity measurements.

    PubMed

    Luedeke, K M; Koehler, J; Kanzenbach, J

    1979-06-01

    In the past, biomedical temperature measurements by microwave radiometry suffered from variable mismatch (emissivity less than 1) between the specimen under test and the receiving antenna. We have developed an improved radiometer, which simultaneously measures temperature and emissivity, independent by of a possible mismatch. Comparative measurements demonstrate the superiority of the new system as compared to conventional ones. PMID:259079

  13. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    SciTech Connect

    Echániz, T. [Departamento de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, UPV/EHU, Sarriena s/n, Leioa 48940 (Spain); Pérez-Sáez, R. B., E-mail: raul.perez@ehu.es; Tello, M. J. [Departamento de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, UPV/EHU, Sarriena s/n, Leioa 48940 (Spain); Instituto de Síntesis y Estudio de Materiales, Universidad del País Vasco, Apdo. 644, Bilbao 48080 (Spain)

    2014-09-07

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ?{sub peak} at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ?{sub peak} increases with the emission angle but its position, ?{sub peak}, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p?=?1.

  14. Optical properties of metals: Infrared emissivity in the anomalous skin effect spectral region

    NASA Astrophysics Data System (ADS)

    Echániz, T.; Pérez-Sáez, R. B.; Tello, M. J.

    2014-09-01

    When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak ?peak at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that ?peak increases with the emission angle but its position, ?peak, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can be equal to one for roughness values larger than those predicted. An exhaustive analysis of the experimental optical parameters shows signs of a reflectance broad peak in Cu, Al, Au, and Mo around the wavelength predicted by the theory for p = 1.

  15. Simulation of Seasonal Snow Microwave TB Using Coupled Multi-Layered Snow Evolution and Microwave Emission Models

    NASA Technical Reports Server (NTRS)

    Brucker, Ludovic; Royer, Alain; Picard, Ghislain; Langlois, Alex; Fily, Michel

    2014-01-01

    The accurate quantification of SWE has important societal benefits, including improving domestic and agricultural water planning, flood forecasting and electric power generation. However, passive-microwave SWE algorithms suffer from variations in TB due to snow metamorphism, difficult to distinguish from those due to SWE variations. Coupled snow evolution-emission models are able to predict snow metamorphism, allowing us to account for emissivity changes. They can also be used to identify weaknesses in the snow evolution model. Moreover, thoroughly evaluating coupled models is a contribution toward the assimilation of TB, which leads to a significant increase in the accuracy of SWE estimates.

  16. A Semi-Empirical Emissivity Model for use in Passive Microwave Precipitation Retrievals Over Land

    NASA Astrophysics Data System (ADS)

    Ringerud, S.; Kummerow, C. D.; Peters-Lidard, C. D.

    2013-12-01

    The upcoming NASA Global Precipitation Measurement Mission (GPM) offers the opportunity for greatly increased understanding of global rainfall and the hydrologic cycle. The GPM algorithm team has made improvement in passive microwave remote sensing of precipitation over land a priority for this mission, and developed a framework allowing for algorithm advancement for individual land surface types as new techniques are developed. An accurate understanding of land surface emissivity in terms of associated surface properties is necessary for any physically-based retrieval scheme over land. This is a complex problem for passive microwave sensors, as the emissivity of land surfaces in the microwave region is large and dynamic, making it difficult to distinguish hydrometeor signal from the highly variable surface emission. In an effort to understand and model the surface emissivity, a semi-empirical technique is developed and tested over the US Southern Great Plains (SGP) area. A physical model is used to calculate emissivity at the 10 GHz frequency, combining contributions from the underlying soil as well as vegetation layers, including the dielectric and roughness effects of each medium. Radiative transfer through each layer is calculated. Adjustments are added for post-precipitation surface water emissivity effects on both the soil and water-coated vegetation. A 5-year dataset of retrieved emissivities from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) is employed for calculation of a robust set of channel covariances. These covariances, combined with the modeled 10 GHz emissivities, provide emissivity values for each AMSR-E channel, which are then used to compute top of the atmosphere brightness temperatures (TBs). Initial results comparing these calculated TBs to observed values show correlations of 0.87-0.97, with the lowest correlations appearing in the highest frequencies of the microwave window region. Such a modeling system could be easily implemented for the emissivity calculation required for physical precipitation retrievals by GPM over similar land surfaces.

  17. Influence of microwave frequency electromagnetic radiation on terpene emission and content in aromatic plants.

    PubMed

    Soran, Maria-Loredana; Stan, Manuela; Niinemets, Ülo; Copolovici, Lucian

    2014-09-15

    Influence of environmental stress factors on both crop and wild plants of nutritional value is an important research topic. The past research has focused on rising temperatures, drought, soil salinity and toxicity, but the potential effects of increased environmental contamination by human-generated electromagnetic radiation on plants have little been studied. Here we studied the influence of microwave irradiation at bands corresponding to wireless router (WLAN) and mobile devices (GSM) on leaf anatomy, essential oil content and volatile emissions in Petroselinum crispum, Apium graveolens and Anethum graveolens. Microwave irradiation resulted in thinner cell walls, smaller chloroplasts and mitochondria, and enhanced emissions of volatile compounds, in particular, monoterpenes and green leaf volatiles (GLV). These effects were stronger for WLAN-frequency microwaves. Essential oil content was enhanced by GSM-frequency microwaves, but the effect of WLAN-frequency microwaves was inhibitory. There was a direct relationship between microwave-induced structural and chemical modifications of the three plant species studied. These data collectively demonstrate that human-generated microwave pollution can potentially constitute a stress to the plants. PMID:25050479

  18. Consideration on the Mechanism of Microwave Emission Due to Rock Fracture

    NASA Astrophysics Data System (ADS)

    Takano, Tadashi; Sugita, Seiji; Yoshida, Shingo; Maeda, Takashi

    2010-05-01

    Microwave emission due to rock fracture was found at 300 MHz, 2 GHz, and 22 GHz, and its power was calibrated in laboratory for the first time in the world. The observed waveform is impulsive, and contains correspondent frequency component inside the envelope at each frequency band. At such high frequencies, the electro-magnetic signal power can be calibrated as a radiating wave with high accuracy. Accordingly, it was verified that a substantial power is emitted. The microwave emission phenomena were also observed on occasions of hypervelocity impact, and esteemed as phenomena generally associated with material destruction. Earthquakes and volcanic activities are association with rock fractures so that the microwave is expected to be emitted. Actually, the e emission was confirmed by the data analysis of the brightness temperature obtained by a remote sensing satellite, which flew over great earthquakes of Wuenchan and Sumatra, and great volcanic eruptions of Reventador and Chanten. It is important to show the microwave emission during rock fracture in natural phenomena. Therefore, the field test to detect the microwave due to the collapse of a crater cliff was planned and persecuted at the volcano of Miyake-jima about 100 km south of Tokyo. Volcanic activity may be more convenient than an earthquake because of the known location and time. As a result, they observed the microwave emission which was strongly correlated with the cliff collapses. Despite of the above-mentioned phenomenological fruits, the reason of the microwave emission is not fixed yet. We have investigated the mechanism of the emission in consideration of the obtained data in rock fracture experiments so far and the study results on material destruction by hypervelocity impact. This paper presents the proposal of the hypothesis and resultant discussions. The microwave sensors may be useful to monitor natural hazards such as an earthquake or a volcanic eruption, because the microwave due to rock fracture can penetrate the ionosphere and can be received by a satellite in orbit. However, the relation between a rock fracture and quakes has not been clarified at all, and is left to the future research. Please fill in your abstract text.

  19. Inter-Sensor Comparison of Microwave Land Surface Emissivity Products to Improve Precipitation Retrievals

    NASA Astrophysics Data System (ADS)

    Norouzi, H.; Temimi, M.; Turk, J.; Prigent, C.; Furuzawa, F.; Tian, Y.

    2013-12-01

    Microwave land surface emissivity acts as the background signal to estimate rain rate, cloud liquid water, and total precipitable water. Therefore, its accuracy can directly affect the uncertainty of such measurements. Over land, unlike over oceans, the microwave emissivity is relatively high and and varies significantly as surface conditions and land cover change. Lack of ground truth measurement of microwave emissivity especially on global scale has made the uncertainty analysis of this parameter very challenging. The present study investigates the consistency among the existing global land emissivity estimates from different microwave sensors. The products are determined from various sensors and frequencies ranging from 7 to 90 GHz. The selected emissivity products in this study are from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) by NOAA - Cooperative remote Sensing and Science and Technology Center (CREST), the Special Sensor Microwave Imager (SSM/I) by The Centre National de la Recherche Scientifique (CNRS) in France, TRMM Microwave Imager (TMI) by Nagoya University, Japan, and WindSat by NASA Jet Propulsion Laboratory (JPL). The emissivity estimates are based on different algorithms and ancillary data sets. This work investigates the difference among these emissivity products from 2003 to 2008 dynamically and spectrally. The similarities and discrepancies of the retrievals are studied at different land cover types. The mean relative difference (MRD) and other statistical parameters are calculated temporally for all five years of the study. Some inherent discrepancies between the selected products can be attributed to the difference in geometry in terms of incident angle, spectral response, and the foot print size which can affect the estimations. The results reveal that in lower frequencies (=<19 GHz) ancillary data especially skin temperature data set is the major source of difference in emissivity retrievals, while in higher frequencies (>19 GHz) the residuals of atmospheric effect on the signal cause inconsistency among the products. The time series and correlation between emissivity maps were analyzed over different land classes to assess the consistency of emissivity variations with geophysical variable such as soil moisture, precipitation, and vegetation.

  20. The field emission of vacuum filtered graphene films reduced by microwave

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Feng, Tao; Qian, Min; Ding, Hui; Chen, Yiwei; Sun, Zhuo

    2011-04-01

    A green, convenient, and inexpensive approach to producing graphene field emitters has been developed. Graphite oxide (GO) produced by hummer method was reduced to graphene in a microwave synthesis system. The vacuum filtration method made it possible to form pure and uniform graphene thin films without any additives and it's easy to transfer to other substrates. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-vis diffuse reflectance spectroscopy (UV-vis) measurements proved that the graphene prepared by microwave has nearly the same reduction level as that prepared by hydrazine. The results of field emission testing demonstrated that graphene films reduced by microwave are more suitable as field emitters than those reduced by hydrazine, which pave a way to mass-produce low-cost graphene emitter for field emission applications.

  1. The microwave emission and transmission characters of deciduous forest at L-band

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongjun; Yuan, Yu; Zheng, Xingming; Zhu, Xiaoming; Fu, Xiuli

    2014-11-01

    Forest covers about 30% of earth surface, which plays an important role in global forecast and carbon cycle. Monitoring forest biomass, and retrieving soil moisture at forest area, are the main goals of most passive microwave sensors on satellite missions. L-band is the most sensitive frequency among all the frequencies due to its good penetration ability. Because of its variety of the size of scattering components, the complicated structures and species of forest, it is difficult to describe the scattering and attenuation characters of forest in modeling microwave emission at forest area. In this paper, we studied the emissivity and transmissivity of deciduous forest at L(1.4GHz) by model simulation and field experiment. The microwave emission model was based on Matrix-Doubling algorithm. The comparison between simulated emissivity and measured data collected during an experiment at Maryland, USA in 2007 was good. Since theoretical model like Matrix-Doubling is too complicated to be used in retrial application, we mapped the results of Matrix-Doubling to a simple 0th-order model, also called ?-? model, by setting the simulated emissivity to be the emissivity of 0th-order model at the same environment, which 2 unknown variables---opacity ? and effective single scattering albedo ? need to be determined. To valited ? (transmissivity of forest) simulated by Matrix-Doubling, we took an deciduous forest experiment by an L band microwave radiometer under trees at JingYueTan area, Changchun, Jilin Province in April to June in 2014. Thus the ? of forest can be determined. The matching results are presented in this paper. The relationship between LAI and forest microwave characters are discussed.

  2. [Study of the microwave emissivity characteristics of vegetation over the Northern Hemisphere].

    PubMed

    Shi, Li-Juan; Qiu, Yu-Bao; Shi, Jian-Cheng

    2013-05-01

    The microwave emissivity is a function of structure, water content, and surface roughness, and all these factors have obvious seasonal variations. In the present study, the half-month averaged emissivities in summer and winter of 2003 over the vegetation of Northern Hemisphere were estimated using Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) combined with IGBP (International Geosphere-Biosphere Project labels) land classification data. Then the emissivities of vegetation land covers at different frequencies, the polarization and their seasonal variations were analyzed respectively. The results show that the emissivities of vegetation increase with the increase in frequencies, and decline with the frequency increasing over snow region. In summer, the vegetation emissivity at V-polarization of 89 GHz is larger than 0.944, and all emissivities are relatively stable and the RMSE of time series emissivity variation is less than 0.007 2. In winter, emissivities decrease over snow covered area, especially for higher frequencies. Furthermore, with the increase in vegetation density, the emissivities increase and emissivity polarization difference decreases. PMID:23905309

  3. Acoustic emission feedback control for control of boiling in a microwave oven

    DOEpatents

    White, Terry L. (Oak Ridge, TN)

    1991-01-01

    An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

  4. Microwave millisecond spike emission and its associated phenomena during the impulsive phase of large flares

    NASA Technical Reports Server (NTRS)

    Li, Chunsheng; Jiang, Shuying; Li, Hongwei; Fu, Qi-Jun

    1986-01-01

    A tentative model is proposed to account for some features of the microwave millisecond spike emission and its links with the physical processes of associated phenomena during the impulsive phase of large flares by comparing the optical, radio, and X-ray observations on May 16, 1981 to those on October 12, 1981.

  5. Emission of non-thermal microwave radiation by a Martian dust storm Christopher Ruf,1

    E-print Network

    Ruf, Christopher

    of microwave emission by Mars were made from 22 May to 16 June 2006 using antenna DSS-13 of NASA's Deep Space detector on DSS-13 was evaluated using the Mars Reconnaissance Orbiter (MRO) communication link as a test beacon (Figure S2). The results demonstrate that (1) the sinusoidal MRO signal lowers the kurtosis

  6. A global high-resolution microwave emission model for the Earth

    Microsoft Academic Search

    G. Schiavon; P. Ferrazzoli; D. Solimini; P. de Maagt; J. P. V. Poiares Baptista

    1998-01-01

    This paper reports on a numerical model developed to simulate vertically and horizontally polarized microwave emission from the Earth in the frequency range between 5 and 50 GHz and at various angles of observation, with a 1°×1° (latitude by longitude) spatial resolution, taking into account seasonal variations. The principal motivation of the model is the evaluation of the noise antenna

  7. AN EMPIRICAL RELATION FOR THE SOIL MOISTURE MEASUREMENT USING EMISSIVITY VALUES AT MICROWAVE FREQUENCY RANGE

    Microsoft Academic Search

    Z. C. Alex; J. Behari; Elizabeth Rufus; A. V. Karpagam

    2001-01-01

    The potential of passive microwave radiometry for the soil moisture measurement is a well established one, especially in the long wave length regions due to its high penetrating capacity through vegetation. Radiometric data can be used as a mapping tool for classifying the crops, examining their health and viability and monitoring the farming practices. The radiometric data or the emission

  8. Detection of microwave emission from solid targets ablated with an ultrashort pulsed laser

    Microsoft Academic Search

    Joseph A. Miragliotta; Benjamin Brawley; Caroline Sailor; James B. Spicer; Jane W. M. Spicer

    2011-01-01

    In addition to visible and near-IR emission, recent investigations have shown that electromagnetic pulses (EMP) in the microwave and RF regions of the spectrum are generated during femtosecond laser-matter interactions if the laser source is sufficiently intense to ablate and ionize an illuminated solid target material. Although the mechanisms for the laserinduced EMP pulse are not fully characterized, it is

  9. MICROWAVE AND HARD XRAY OBSERVATIONS OF FOOTPOINT EMISSION FROM SOLAR FLARES

    E-print Network

    White, Stephen

    radio and X­ray imaging data for two solar flares in order to test the idea that asymmetric on the Yohkoh spacecraft, and by the Nobeyama 17 GHz radioheliograph. The hard X­ray images in one case show twoMICROWAVE AND HARD X­RAY OBSERVATIONS OF FOOTPOINT EMISSION FROM SOLAR FLARES M. R. KUNDU Dept

  10. [Study of the microwave emissivity characteristics over different land cover types].

    PubMed

    Zhang, Yong-Pan; Jiang, Ling-Mei; Qiu, Yu-Bao; Wu, Sheng-Li; Shi, Jian-Cheng; Zhang, Li-Xin

    2010-06-01

    The microwave emissivity over land is very important for describing the characteristics of the lands, and it is also a key factor for retrieving the parameters of land and atmosphere. Different land covers have their emission behavior as a function of structure, water content, and surface roughness. In the present study the global land surface emissivities were calculated using six month (June, 2003-August, 2003, Dec, 2003-Feb, 2004) AMSR-E L2A brightness temperature, MODIS land surface temperature and the layered atmosphere temperature, and humidity and pressure profiles data retrieved from MODIS/Aqua under clear sky conditions. With the information of IGBP land cover types, "pure" pixels were used, which are defined when the fraction cover of each land type is larger than 85%. Then, the emissivity of sixteen land covers at different frequencies, polarization and their seasonal variation were analyzed respectively. The results show that the emissivity of vegetation including forests, grasslands and croplands is higher than that over bare soil, and the polarization difference of vegetation is smaller than that of bare soil. In summer, the emissivity of vegetation is relatively stable because it is in bloom, therefore the authors can use it as its emissivity in our microwave emissivity database over different land cover types. Furthermore, snow cover can heavily impact the change in land cover emissivity, especially in winter. PMID:20707126

  11. Characterization of errors in a coupled snow hydrology-microwave emission model

    USGS Publications Warehouse

    Andreadis, K.M.; Liang, D.; Tsang, L.; Lettenmaier, D.P.; Josberger, E.G.

    2008-01-01

    Traditional approaches to the direct estimation of snow properties from passive microwave remote sensing have been plagued by limitations such as the tendency of estimates to saturate for moderately deep snowpacks and the effects of mixed land cover within remotely sensed pixels. An alternative approach is to assimilate satellite microwave emission observations directly, which requires embedding an accurate microwave emissions model into a hydrologic prediction scheme, as well as quantitative information of model and observation errors. In this study a coupled snow hydrology [Variable Infiltration Capacity (VIC)] and microwave emission [Dense Media Radiative Transfer (DMRT)] model are evaluated using multiscale brightness temperature (TB) measurements from the Cold Land Processes Experiment (CLPX). The ability of VIC to reproduce snowpack properties is shown with the use of snow pit measurements, while TB model predictions are evaluated through comparison with Ground-Based Microwave Radiometer (GBMR), air-craft [Polarimetric Scanning Radiometer (PSR)], and satellite [Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E)] TB measurements. Limitations of the model at the point scale were not as evident when comparing areal estimates. The coupled model was able to reproduce the TB spatial patterns observed by PSR in two of three sites. However, this was mostly due to the presence of relatively dense forest cover. An interesting result occurs when examining the spatial scaling behavior of the higher-resolution errors; the satellite-scale error is well approximated by the mode of the (spatial) histogram of errors at the smaller scale. In addition, TB prediction errors were almost invariant when aggregated to the satellite scale, while forest-cover fractions greater than 30% had a significant effect on TB predictions. ?? 2008 American Meteorological Society.

  12. Land Surface Microwave Emissivities Derived from AMSR-E and MODIS Measurements with Advanced Quality Control

    NASA Technical Reports Server (NTRS)

    Moncet, Jean-Luc; Liang, Pan; Galantowicz, John F.; Lipton, Alan E.; Uymin, Gennady; Prigent, Catherine; Grassotti, Christopher

    2011-01-01

    A microwave emissivity database has been developed with data from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and with ancillary land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the same Aqua spacecraft. The primary intended application of the database is to provide surface emissivity constraints in atmospheric and surface property retrieval or assimilation. An additional application is to serve as a dynamic indicator of land surface properties relevant to climate change monitoring. The precision of the emissivity data is estimated to be significantly better than in prior databases from other sensors due to the precise collocation with high-quality MODIS LST data and due to the quality control features of our data analysis system. The accuracy of the emissivities in deserts and semi-arid regions is enhanced by applying, in those regions, a version of the emissivity retrieval algorithm that accounts for the penetration of microwave radiation through dry soil with diurnally varying vertical temperature gradients. These results suggest that this penetration effect is more widespread and more significant to interpretation of passive microwave measurements than had been previously established. Emissivity coverage in areas where persistent cloudiness interferes with the availability of MODIS LST data is achieved using a classification-based method to spread emissivity data from less-cloudy areas that have similar microwave surface properties. Evaluations and analyses of the emissivity products over homogeneous snow-free areas are presented, including application to retrieval of soil temperature profiles. Spatial inhomogeneities are the largest in the vicinity of large water bodies due to the large water/land emissivity contrast and give rise to large apparent temporal variability in the retrieved emissivities when satellite footprint locations vary over time. This issue will be dealt with in the future by including a water fraction correction. Also note that current reliance on the MODIS day-night algorithm as a source of LST limits the coverage of the database in the Polar Regions. We will consider relaxing the current restriction as part of future development.

  13. High-power microwave emission by magnetized virtual cathode oscillator

    SciTech Connect

    Kostov, K.G.; Ferreira, J.L. [Univ. of Brasilia (Brazil). Dept. of Physics

    1996-12-31

    The results of computer simulation of an axially extracted virtual cathode oscillator with an external guide magnetic field are presented. The simulation was performed using the electromagnetic relativistic particle-in-cell (PIC) computer code KARAT. The foil diode parameters as accelerating voltage, cathode diameter and anode-cathode gap are chosen in such a way that the beam current injected through the anode foil into the output waveguide exceeds the space charge limited current but on the outer side it is below the critical current for beam pinching. In this case without using an external guide magnetic field the beam expands in radial direction until it hits the conductive wall. It is shown that the vircator can operate with and without magnetic field however in the case without guide magnetic field the vircator efficiency is small due to the current losses in radial direction. The emitted microwave power with guide magnetic field is bigger than in the case without magnetic field and the microwave frequency slightly increase with magnetic field intensity increasing. The results from computer simulation are compared with experimental results obtained in a similar vircator configuration.

  14. Study on microwave emission mechanisms on the basis of hypervelocity impact experiments on various target plates

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Chiba, S.; Soma, E.; Ishii, K.; Maki, K.; Takano, T.; Hasegawa, S.

    2007-06-01

    It was formerly confirmed by experiment that hypervelocity impacts on aluminum plates cause microwave emission. In this study, we have carried out experiments in order to clarify the mechanism of the emission. The microwave is detected by heterodyne detection scheme at 22 and 2 GHz with an intermediate frequency bandwidth of 500 and 120 MHz, respectively. A nylon projectile is accelerated using a light-gas gun to impact a target. First, aluminum plates with ten different thicknesses ranging from 1 to 40 mm were used as a target, and microwave signals were detected. The experimental results are statistically analyzed assuming a Gaussian distribution of the emitted power. The standard deviation of pulse voltage is calculated to show the existence of two kinds of signals: sharp pulse and thermal noise. It is shown that the emitted energy and the dispersion have a relation with the extent of the target destruction. Next, nylon projectiles are impacted on different metals such as aluminum, iron, and copper. These results suggest that microcracks are essential to microwave emission. Finally, in order to clarify the mechanism of charging and discharging across the microcracks, the experimental results are compared with this model for the following factors: (1) the thermally excited electrons and the emitted power, and (2) the bond dissociation energy of target material and emitted power. The analytical results suggest that electrons are excited thermally and by transition from a crystalline state to an atomic state.

  15. Anomalous hydrogen emissions from the San Andreas fault observed at the Cienega Winery, central California

    USGS Publications Warehouse

    Sato, M.; Sutton, A.J.; McGee, K.A.

    1985-01-01

    We began continuous monitoring of H2 concentration in soil along the San Andreas and Calaveras faults in central California in December 1980, using small H2/O2 fuel-cell sensors. Ten monitoring stations deployed to date have shown that anomalous H2 emissions take place occasionally in addition to diurnal changes. Among the ten sites, the Cienega Winery site has produced data that are characterized by very small diurnal changes, a stable baseline, and remarkably distinct spike-like H2 anomalies since its installation in July 1982. A major peak appeared on 1-10 November 1982, and another on 3 April 1983, and a medium peak on 1 November 1983. The occurrences of these peaks coincided with periods of very low seismicity within a radius of 50 km from the site. In order to methodically assess how these peaks are related to earthquakes, three H2 degassing models were examined. A plausible correlational pattern was obtained by using a model that (1) adopts a hemicircular spreading pattern of H2 along an incipient fracture plane from the hypocenter of an earthquake, (2) relies on the FeO-H2O reaction for H2 generation, and (3) relates the accumulated amount of H2 to the mass of serpentinization of underlying ophiolitic rocks; the mass was tentatively assumed to be proportional to the seismic energy of the earthquake. ?? 1985 Birkha??user Verlag.

  16. Microwave emission from plasmas produced by magnetically confined-electron beams

    Microsoft Academic Search

    Donald P. Murphy; Richard F. Fernsler; Robert E. Pechacek; Robert A. Meger

    2002-01-01

    Microwave emission, in the x-band frequency range (8.2-12.4 GHz), from a thin, large, rectangular sheet plasma has been measured. The plasma electron density was such that the plasma frequency was within or just above this frequency range. The plasma was immersed in an external magnetic field from a set of Helmholz coils. The magnetic field was oriented parallel to the

  17. Impact of Conifer Forest Litter on Microwave Emission at L-Band

    NASA Technical Reports Server (NTRS)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.

    2011-01-01

    This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.

  18. The Microwave Thermal Emission from the Zodiacal Dust Cloud Predicted with Contemporary Meteoroid Models

    E-print Network

    Dikarev, Valery V

    2015-01-01

    Predictions of the microwave thermal emission from the interplanetary dust cloud are made using several contemporary meteoroid models to construct the distributions of cross-section area of dust in space, and applying the Mie light-scattering theory to estimate the temperatures and emissivities of dust particles in broad size and heliocentric distance ranges. In particular, the model of the interplanetary dust cloud by Kelsall et al. (1998, ApJ 508: 44-73), the five populations of interplanetary meteoroids of Divine (1993, JGR 98(E9): 17,029-17,048) and the Interplanetary Meteoroid Engineering Model (IMEM) by Dikarev et al. (2004, EMP 95: 109-122) are used in combination with the optical properties of olivine, carbonaceous and iron spherical particles. The Kelsall model has been widely accepted by the Cosmic Microwave Background (CMB) community. We show, however, that it predicts the microwave emission from interplanetary dust remarkably different from the results of application of the meteoroid engineering m...

  19. Relative influence upon microwave emissivity of fine-scale stratigraphy, internal scattering, and dielectric properties

    USGS Publications Warehouse

    England, A.W.

    1976-01-01

    The microwave emissivity of relatively low-loss media such as snow, ice, frozen ground, and lunar soil is strongly influenced by fine-scale layering and by internal scattering. Radiometric data, however, are commonly interpreted using a model of emission from a homogeneous, dielectric halfspace whose emissivity derives exclusively from dielectric properties. Conclusions based upon these simple interpretations can be erroneous. Examples are presented showing that the emission from fresh or hardpacked snow over either frozen or moist soil is governed dominantly by the size distribution of ice grains in the snowpack. Similarly, the thickness of seasonally frozen soil and the concentration of rock clasts in lunar soil noticeably affect, respectively, the emissivities of northern latitude soils in winter and of the lunar regolith. Petrophysical data accumulated in support of the geophysical interpretation of microwave data must include measurements of not only dielectric properties, but also of geometric factors such as finescale layering and size distributions of grains, inclusions, and voids. ?? 1976 Birkha??user Verlag.

  20. Assessment of the consistency among global microwave land surface emissivity products

    NASA Astrophysics Data System (ADS)

    Norouzi, H.; Temimi, M.; Prigent, C.; Turk, J.; Khanbilvardi, R.; Tian, Y.; Furuzawa, F.; Masunaga, H.

    2014-09-01

    The goal of this work is to inter-compare a number of global land surface emissivity products over various land-cover conditions to assess their consistency. Ultimately, the discrepancies between the studied emissivity products will help interpreting the divergences among numerical weather prediction models in which land emissivity is a key surface boundary parameter. The intercompared retrieved land emissivity products were generated over five-year period (2003-2007) using observations from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), Special Sensor Microwave Imager (SSM/I), The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Windsat. First, all products were reprocessed in the same projection and spatial resolution as they were generated from sensors with various configurations. Then, the mean value and standard deviations of monthly emissivity values were calculated for each product to assess the spatial distribution of the consistencies/inconsistencies among the products across the globe. The emissivity values from four products were also compared to soil moisture estimates and satellite-based vegetation index to assess their sensitivities to the changes in land surface conditions. Results show that systematic differences among products exist and variation of emissivities at each product has similar frequency dependency at any land cover type. Monthly means of emissivity values from AMSR-E in the vertical and horizontal polarizations seem to be systematically lower across various land cover condition which may be attributed to the 1.30 a.m./p.m. overpass time of the sensor and possibly a residual skin temperature effect in the product. The standard deviation of the analysed products was the lowest (less than 0.01) in rain forest regions for all products and the highest in northern latitudes, above 0.04 for AMSR-E and SSM/I and around 0.03 for WindSat. Despite differences in absolute emissivity estimates, all products were similarly sensitive to changes in soil moisture and vegetation. The correlation between the emissivity polarization differences and NDVI values showed similar spatial distribution across the products with values close to the unit except over densely vegetated and desert areas.

  1. MEMLS3&a: Microwave Emission Model of Layered Snowpacks adapted to include backscattering

    NASA Astrophysics Data System (ADS)

    Proksch, M.; Mätzler, C.; Wiesmann, A.; Lemmetyinen, J.; Schwank, M.; Löwe, H.; Schneebeli, M.

    2015-03-01

    The Microwave Emission Model of Layered Snowpacks (MEMLS) was originally developed for microwave emissions of snowpacks in the frequency range 5-100 GHz. It is based on six-flux theory to describe radiative transfer in snow including absorption, multiple volume scattering, radiation trapping due to internal reflection and a combination of coherent and incoherent superposition of reflections between horizontal layer interfaces. Here we introduce MEMLS3&a, an extension of MEMLS, which includes a backscatter model for active microwave remote sensing of snow. The reflectivity is decomposed into diffuse and specular components. Slight undulations of the snow surface are taken into account. The treatment of like and cross polarization is accomplished by an empirical splitting parameter q. MEMLS3&a (as well as MEMLS) is set up in a way that snow input parameters can be derived by objective measurement methods which avoids fitting procedures of the scattering efficiency of snow, required by several other models. For the validation of the model we have used a combination of active and passive measurements from the NoSREx campaign in Sodankylä, Finland. We find a reasonable agreement between the measurements and simulations, subject to uncertainties in hitherto unmeasured input parameters of the backscatter model. The model is written in MATLAB and the code is publicly available for download through the following website: http://www.iapmw.unibe.ch/research/projects/snowtools/memls.html.

  2. Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer

    PubMed Central

    Pulvirenti, Luca; Pierdicca, Nazzareno; Marzano, Frank S.

    2008-01-01

    A simulation study to understand the influence of topography on the surface emissivity observed by a satellite microwave radiometer is carried out. We analyze the effects due to changes in observation angle, including the rotation of the polarization plane. A mountainous area in the Alps (Northern Italy) is considered and the information on the relief extracted from a digital elevation model is exploited. The numerical simulation refers to a radiometric image, acquired by a conically-scanning radiometer similar to AMSR-E, i.e., flying at 705 km of altitude with an observation angle of 55°. To single out the impact on surface emissivity, scattering of the radiation due to the atmosphere or neighboring elevated surfaces is not considered. C and X bands, for which atmospheric effects are negligible, and Ka band are analyzed. The results indicate that the changes in the local observation angle tend to lower the apparent emissivity of a radiometric pixel with respect to the corresponding flat surface characteristics. The effect of the rotation of the polarization plane enlarges (vertical polarization), or attenuates (horizontal polarization) this decrease. By doing some simplifying assumptions for the radiometer antenna, the conclusion is that the microwave emissivity at vertical polarization is underestimated, whilst the opposite occurs for horizontal polarization, except for Ka band, for which both under- and overprediction may occur. A quantification of the differences with respect to a flat soil and an approximate evaluation of their impact on soil moisture retrieval are yielded.

  3. Impact of the seasonal evolution of snow properties on microwave emission model performance

    NASA Astrophysics Data System (ADS)

    Fuller, M.; Derksen, C.; Lemmetyinen, J.; Yackel, J.

    2010-12-01

    Snow cover exhibits great spatio-temporal variability, and is dynamically coupled with global hydrological and climatological processes. Accounting for snowpack evolution related to snow accumulation, metamorphosis, and melt are essential for both modeling and remote sensing applications. Microwave emission has frequency dependant relationships with snow water equivalent (SWE), but snow grain-size, snowpack layering, and snow liquid-water content can confuse the estimation of snow parameters with empirical stand-alone algorithms. This work presents an overview of seasonal snow and multi-frequency dual-polarization microwave emission measurements collected during the 2009-2010 winter season at a network of sites near Churchill, Manitoba, Canada. These observations were used to parameterize and evaluate model simulations of microwave snow emission using the multiple-layer version of the Helsinki University of Technology (HUT) microwave emission model. The HUT model is utilized in the European Space Agency’s (ESA) GlobSnow global snow monitoring service, applied to SWE and snow depth (SD) retrievals for the Northern Hemisphere. The HUT model used for forward brightness temperature simulations in the GlobSnow retrieval scheme is currently limited to one layer which necessitates idealizing physical properties of the entire snow pack. In this study, we explore the performance of simulations with the addition of a depth hoar layer and, when appropriate, an ice lens. Simulations for forest, lake, and open environments were synthesized through a scene simulation formulation of the HUT model to produce output suitable for comparison with measured brightness temperatures from the Advanced Microwave Scanning Radiometer (AMSR-E). While the multi-layer model better represents the vertical complexities of grain size and layering, implementation of a multi-layer approach remains a challenge due to model sensitivity with regard to the method of generalization of a complex snow pack into multiple layers. The addition of a second snow layer had a notable impact on 37 GHz simulations because of model sensitivity to the determination of grain size. By reserving one model layer for an ice lens, notable improvements can be made with horizontal polarization simulations at both 19 and 37 GHz.

  4. On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission

    Microsoft Academic Search

    Nathaniel R. Butler

    2006-01-01

    We have conducted a thorough and blind search for emission lines in >70 Swift\\u000aX-ray afterglows of total exposure ~10^7s. We find that most afterglows are\\u000aconsistent with pure power-laws plus extinction. Significant outliers to the\\u000apopulation exist at the 5-10% level and have anomalously soft, possibly thermal\\u000aspectra. Four bursts are singled out via possible detections of 2-5 lines:

  5. Development of a land surface emissivity algorithm for use by microwave rain retrieval algorithms

    NASA Astrophysics Data System (ADS)

    Furuzawa, Fumie A.; Masunaga, Hirohiko; Nakamura, Kenji

    2012-11-01

    We have been developing a data-set of global land surface microwave emissivity calculated from 9-channel Bright­ ness Temperatures (TBs) from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and atmospheric profile data from Japanese 25-year Reanalysis Project (JRA-25). The surface emissivity is derived using the non-scattering radiative transfer equation for regions identified as no-rain by TRMM Precipitation Radar (PR). An Empirical Orthogonal Function (EOF) analysis has been applied to this emissivity data-set. Emissivities at high frequencies, difficult to estimate due to high sensitivity to clouds and water vapor, are estimated from lower frequencies by using the principal components. Contributions from EOF1 to EOF4 are dominant and with the others being less than 1 %. Therefore, 5 high-frequency emissivities can be estimated from the other 4 emissivities at lower frequencies with 4 principal components. For example, when 37 GHz Horizontal emissivity on June 1998 is estimated from 4 channels of 10 and 19 GHz, correlation coefficient with the original estimate is 0.93 and the result of linear fitting shows an inclination of 0.97 and a cutoff of 0.02 for global data. This estimation method is applied for each area, each land surface condition (surface type and soil wetness) and so on, in search of optimal performance of the algorithm. The advantage of using the EOF analysis as described above is to minimize the cloud contamination at high frequency TB. A cloud-clearing method is also explored to improve the reliability of the EOFs.

  6. Anomalous scattering factor using proton induced X-ray emission technique

    NASA Astrophysics Data System (ADS)

    Latha, P.; Magudapathy, P.; Abdullah, K. K.; Nair, K. G. M.; Babu, B. R. S.; Varier, K. M.

    2015-02-01

    Atomic scattering factor is in general a complex number represented by the sum of normal scattering factor (f0) and anomalous scattering factors [real (f ?) and imaginary (f ?)]. Anomalous scattering factors in Ag, In, Cd and Sn were determined experimentally from attenuation data measured using PIXE and compared with theoretical values. The data cover the energy region from 10 to 30 keV and atomic number Z from 47 to 50 keV. Our results found to be in close agreement with theoretical values.

  7. Microwave emissivity of freshwater ice, Part II: Modelling the Great Bear and Great Slave Lakes

    E-print Network

    Mills, Peter

    2012-01-01

    Lake ice within three Advanced Microwave Scanning Radiometer on EOS (AMSR-E) pixels over the Great Bear and Great Slave Lakes have been simulated with the Canadian Lake Ice Model (CLIMo). The resulting thicknesses and temperatures were fed to a radiative transfer-based ice emissivity model and compared to the satellite measurements at three frequencies---6.925 GHz, 10.65 GHz and 18.7 GHz. Excluding the melt season, the model was found to have strong predictive power, returning a correlation of 0.926 and a residual of 0.78 Kelvin at 18 GHz, vertical polarization. Discrepencies at melt season are thought to be caused by the presence of dirt in the snow cover which makes the microwave signature more like soil rather than ice. Except at 18 GHz, all results showed significant bias compared to measured values. Further work needs to be done to determine the source of this bias.

  8. Assessment of the consistency among global microwave land surface emissivity products

    NASA Astrophysics Data System (ADS)

    Norouzi, H.; Temimi, M.; Prigent, C.; Turk, J.; Khanbilvardi, R.; Tian, Y.; Furuzawa, F. A.; Masunaga, H.

    2015-03-01

    The goal of this work is to intercompare four global land surface emissivity products over various land-cover conditions to assess their consistency. The intercompared land emissivity products were generated over a 5-year period (2003-2007) using observations from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E), the Special Sensor Microwave Imager (SSM/I), the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), and WindSat. First, all products were reprocessed in the same projection and spatial resolution as they were generated from sensors with various configurations. Then, the mean value and standard deviations of monthly emissivity values were calculated for each product to assess the spatial distribution of the consistencies/inconsistencies among the products across the globe. The emissivity products were also compared to soil moisture estimates and a satellite-based vegetation index to assess their sensitivities to changes in land surface conditions. Results show the existence of systematic differences among the products. Also, it was noticed that emissivity values in each product have similar frequency dependency over different land-cover types. Monthly means of emissivity values from AMSR-E in the vertical and horizontal polarizations seem to be systematically lower than the rest of the products across various land-cover conditions which may be attributed to the 01:30/13:30 LT overpass time of the sensor and possibly a residual skin temperature effect in the product. The standard deviation of the analyzed products was lowest (less than 0.01) in rain forest regions for all products and highest at northern latitudes, above 0.04 for AMSR-E and SSM/I and around 0.03 for WindSat. Despite differences in absolute emissivity estimates, all products were similarly sensitive to changes in soil moisture and vegetation. The correlation between the emissivity polarization differences and normalized difference vegetation index (NDVI) values showed similar spatial distribution across the products, with values close to the unit except over densely vegetated and desert areas.

  9. Effects of Atmospheric Emission on Ground-based MicrowaveBackground Measurements

    SciTech Connect

    Bersanelli, M.; Bensadoun, M.; Danese, L.; Deamici, G.; Kogut,A.; Levin, S.; Limon, M.; Maino, D.; Smoot, G.F.; Witebsky, C.

    1994-10-20

    We present an analysis of multifrequency measurements ofatmospheric emission in the Rayleigh-Jeans portion of the cosmicmicrowave background spectrum (1-90 GHz) taken since 1986 from WhiteMountain, CA, and from the South Pole. Correlations of simultaneous dataat 10 and 90 GHz and accurate low-frequency measurements show goodagreement with model predictions for both sites. Our data from the SouthPole 1989 campaign combined with real-time measurements of the localatmospheric profiles provide accurate verification of the expectedindependent contributions of H2O and O2 emission. We show that variationson the order of 10 percent of the oxygen emission (both resonant andnonresonant components) are present on timescales of hours to days,mainly due to the evolution of the atmospheric pressure profile. Oxygenemission fluctuations appear larger than previously expected and may havesignificant consequences for ground-based cosmic microwave backgroundexperiments.

  10. Microwave heating rates for a plasma in a dc magnetic field as determined from inverse synchrotron emission

    Microsoft Academic Search

    J. L. Shohet; R. M. Gilgenbach

    1974-01-01

    The microwave heating rate for a plasma in a d.c. magnetic field is found by multiplying the emission rate for a relativistic electron in a d.c. magnetic field by a correction factor corresponding to the number of incident photons and integrating this expression over a particle velocity distribution. The correction factor which relates the absorption rate to the emission rate

  11. Microwave emission from late-type dwarf stars UV Ceti and YZ Canis Minoris

    NASA Astrophysics Data System (ADS)

    Kundu, M. R.; Shevgaonkar, R. K.

    1985-10-01

    Simultaneous high-resolution observations of two late-type dwarf stars, UV Cet and YZ CMi, at 6 and 20 cm are presented. These observations put sufficient constraints on existing interpretations to conclude that the quiescent microwave emission from these stars is due to gyrosynchrotron radiation of nonthermal electrons having a power-law energy distribution. From the lifetime of 1 hr of the nonthermal particles against radiation and collision losses, a magnetic field of a few thousand gauss on the photosphere of these stars is estimated. The observations indicate that the ambient density in the coronae of YZ CMi is an order of magnitude higher than that of UV Cet.

  12. TEMPORAL AND SPATIAL ANALYSES OF SPECTRAL INDICES OF NONTHERMAL EMISSIONS DERIVED FROM HARD X-RAYS AND MICROWAVES

    SciTech Connect

    Asai, Ayumi [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan)] [Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan); Kiyohara, Junko; Takasaki, Hiroyuki [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan)] [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto, 607-8471 (Japan); Narukage, Noriyuki [Institute of Space and Astronomical Science, Japan Aerospace Exploration Agency, Chuo, Sagamihara, Kanagawa, 229-8510 (Japan)] [Institute of Space and Astronomical Science, Japan Aerospace Exploration Agency, Chuo, Sagamihara, Kanagawa, 229-8510 (Japan); Yokoyama, Takaaki [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033 (Japan)] [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033 (Japan); Masuda, Satoshi [Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa, Nagoya, Aichi, 464-8601 (Japan)] [Solar-Terrestrial Environment Laboratory, Nagoya University, Chikusa, Nagoya, Aichi, 464-8601 (Japan); Shimojo, Masumi [National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588 (Japan)] [National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588 (Japan); Nakajima, Hiroshi, E-mail: asai@kwasan.kyoto-u.ac.jp [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano, 384-1305 (Japan)] [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano, 384-1305 (Japan)

    2013-02-15

    We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap {Delta}{delta} between the electron spectral indices derived from HXRs {delta} {sub X} and those from microwaves {delta}{sub {mu}} ({Delta}{delta} = {delta} {sub X} - {delta}{sub {mu}}) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index {delta} {sub X} evolve synchronously with those of the microwave spectral index {delta}{sub {mu}}, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index {delta}{sub {mu}} tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.

  13. Emission spectra from direct current and microwave powered Hg lamps at very high pressure

    NASA Astrophysics Data System (ADS)

    Hamady, M.; Lister, G. G.; Stafford, L.

    2013-11-01

    Discharge lamps containing mercury at pressures above 100 bar are commercially used in data projectors and television projector systems. Due to their small size, these lamps are difficult to investigate experimentally, but spectral measurements, combined with radiation transport calculations, have provided useful information on the visible spectrum. However, classical spectral line broadening theory is inadequate to describe the UV portion of the spectrum, so self-consistent modelling of these discharges is not possible at present. This paper discusses the differences between discharges containing electrodes and discharges sustained by a microwave (mw) electromagnetic field, on the basis of the experimentally measured temperature profile in an electroded discharge, and a temperature profile computed from a 1D power balance model for a microwave discharge. A model based on the ray-tracing method is employed to simulate the radiation transport in these lamps. The model has been validated by comparing the emission spectrum from dc discharge lamps with those obtained experimentally. The output flux, luminous flux, luminous efficacy, the correlated colour temperature, the chromaticity coordinates and photometric curves of the lamp were then obtained. These results were also compared with those of a theoretically calculated temperature profile for the same lamp, excited by microwave power in the TM010 mode.

  14. Analytical Retrieval of Global Land Surface Emissivity Maps at AMSR-E passive microwave frequencies

    NASA Astrophysics Data System (ADS)

    Norouzi, H.; Temimi, M.; Khanbilvardi, R.

    2009-12-01

    Land emissivity is a crucial boundary condition in Numerical Weather Prediction (NWP) modeling. Land emissivity is also a key indicator of land surface and subsurface properties. The objective of this study, supported by NOAA-NESDIS, is to develop global land emissivity maps using AMSR-E passive microwave measurements along with several ancillary data. The International Satellite Cloud Climatology Project (ISCCP) database has been used to obtain several inputs for the proposed approach such as land surface temperature, cloud mask and atmosphere profile. The Community Radiative Transfer Model (CRTM) has been used to estimate upwelling and downwelling atmospheric contributions. Although it is well known that correction of the atmospheric effect on brightness temperature is required at higher frequencies (over 19 GHz), our preliminary results have shown that a correction at 10.7 GHz is also necessary over specific areas. The proposed approach is based on three main steps. First, all necessary data have been collected and processed. Second, a global cloud free composite of AMSR-E data and corresponding ancillary images is created. Finally, monthly composting of emissivity maps has been performed. AMSR-E frequencies at 6.9, 10.7, 18.7, 36.5 and 89.0 GHz have been used to retrieve the emissivity. Water vapor information obtained from ISCCP (TOVS data) was used to calculate upwelling, downwelling temperatures and atmospheric transmission in order to assess the consistency of those derived from the CRTM model. The frequent land surface temperature (LST) determination (8 times a day) in the ISCCP database has allowed us to assess the diurnal cycle effect on emissivity retrieval. Differences in magnitude and phase between thermal temperature and low frequencies microwave brightness temperature have been noticed. These differences seem to vary in space and time. They also depend on soil texture and thermal inertia. The proposed methodology accounts for these factors and resultant differences in phase and magnitude between LST and microwave brightness temperature. Additional factors such as topography and vegetation cover are under investigation. In addition, the potential of extrapolating the obtained land emissivity maps to different window and sounding channels has been also investigated in this study. The extrapolation of obtained emissivities to different incident angles is also under investigation. Land emissivity maps have been developed at different AMSR-E frequencies. Obtained product has been validated and compared to global land use distribution. Moreover, global soil moisture AMSR-E product maps have been also used to assess to the spatial distribution of the emissivity. Moreover, obtained emissivity maps seem to be consistent with landuse/land cover maps. They also agree well with land emissivity maps obtained from the ISCCP database and developed using SSM/I observations (for frequencies over 19 GHz).

  15. Spatial Scaling of Snow Observations and Microwave Emission Modeling During CLPX and Appropriate Satellite Sensor Resolution

    NASA Technical Reports Server (NTRS)

    Kim, Edward J.; Tedesco, Marco

    2005-01-01

    Accurate estimates of snow water equivalent and other properties play an important role in weather, natural hazard, and hydrological forecasting and climate modeling over a range of scales in space and time. Remote sensing-derived estimates have traditionally been of the "snapshot" type, but techniques involving models with assimilation are also being explored. In both cases, forward emission models are useful to understand the observed passive microwave signatures and developing retrieval algorithms. However, mismatches between passive microwave sensor resolutions and the scales of processes controlling subpixel heterogeneity can affect the accuracy of the estimates. Improving the spatial resolution of new passive microwave satellite sensors is a major desire in order to (literally) resolve such subpixel heterogeneity, but limited spacecraft and mission resources impose severe constraints and tradeoffs. In order to maximize science return while mitigating risk for a satellite concept, it is essential to understand the scaling behavior of snow in terms of what the sensor sees (brightness temperature) as well as in terms of the actual variability of snow. NASA's Cold Land Processes Experiment-1 (CLPX-1: Colorado, 2002 and 2003) was designed to provide data to measure these scaling behaviors for varying snow conditions in areas with forested, alpine, and meadow/pasture land cover. We will use observations from CLPX-1 ground, airborne, and satellite passive microwave sensors to examine and evaluate the scaling behavior of observed and modeled brightness temperatures and observed and retrieved snow parameters across scales from meters to 10's of kilometers. The conclusions will provide direct examples of the appropriate spatial sampling scales of new sensors for snow remote sensing. The analyses will also illustrate the effects and spatial scales of the underlying phenomena (e.g., land cover) that control subpixel heterogeneity.

  16. The anomalous 3.43 and 3.53 micron emission features toward HD 97048 and Elias 1 - C-C vibrational modes of polycyclic aromatic hydrocarbons?

    NASA Technical Reports Server (NTRS)

    Schutte, W. A.; Tielens, A. G. G. M.; Allamandola, L. J.; Wooden, D. H.; Cohen, M.

    1990-01-01

    The 5-8 micron spectra obtained toward the two protostellar sources, HD 97048 and Elias 1 exhibit strong anomalous emission features at 3.43 and 3.53 microns. Combining these results with earlier data established that the emission in the general IR features is extended on at least a 20-arcsec scale. In view of the high energy density in the emission zone, as well as the apparent correspondence of the anomalous 3.43 and 3.53 micron features with weak emission shoulders associated with the general family of IR emission bands, an explanation for these observations in terms of C-C overtones and combination tones of large or dehydrogenated polycyclic aromatic hydrocarbons is judged to be provisionally suitable.

  17. Preliminary analysis of Skylab RADSCAT results over the ocean. [using radar backscatter and microwave emission

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Claassen, J. D.; Young, J. D.; Pierson, W. J., Jr.; Cardone, V. J.

    1974-01-01

    Preliminary observations at 13.9 GHz of the radar backscatter and microwave emission from the sea were analyzed using data obtained by the radiometer scatterometer on Skylab. Results indicate approximately a square-law relationship between differential scattering coefficient and windspeed at angles of 40 deg to 50 deg, after correction for directional effect, over a range from about 4 up to about 25 meters/sec. The brightness temperature response was also observed, and considerable success was achieved in correcting it for atmospheric attenuation and emission. Measurements were made in June, 1973, over Hurricane Ava off the west coast of Mexico and over relatively calm conditions in the Gulf of Mexico and Caribbean Sea.

  18. Attenuation statistics derived from emission measurements by a network of ground-based microwave radiometers

    NASA Technical Reports Server (NTRS)

    Westwater, E. R.; Snider, J. B.; Falls, M. J.; Fionda, E.

    1990-01-01

    Two seasons of thermal emission measurements, running from December 1987 through February 1988 and from June through August 1988 of thermal emission measurements, taken by a multi-channel, ground-based microwave radiometer, are used to derive single-station zenith attenuation statistics at 20.6 and 31.65 GHz. For the summer period, statistics are also derived for 52.85 GHz. In addition, data from two dual-channel radiometers, separated from Denver by baseline distances of 49 and 168 km, are used to derive two-station attenuation diversity statistics at 20.6 and 31.65 GHz. The multi-channel radiometer is operated at Denver, Colorado; the dual-channel devices are operated at Platteville and Flagler, Colorado. The diversity statistics are presented by cumulative distributions of maximum and minimum attenuation.

  19. Microwave plasma CVD-grown graphene-CNT hybrids for enhanced electron field emission applications

    NASA Astrophysics Data System (ADS)

    Kaushik, Vishakha; Shukla, A. K.; Vankar, V. D.

    2014-12-01

    The growth and electron emission characteristics were investigated from a hybrid structure of multiwalled carbon nanotubes (MWCNTs) and multilayer layer graphene (MLG) deposited on silicon substrate coated with iron catalyst and an interlayer of aluminium. The hybrid structures were synthesized in a two-step process by microwave plasma-enhanced chemical vapour deposition technique. The formation of MWCNTs takes place by absorption and precipitation of carbon radicals into the catalyst particles. Thereafter, ample carbon forms MLG on tip of the MWCNTs resulting in a MLG-MWCNTs hybrid nanostructure. MLG was observed to grow branching out of the tips and sidewalls of the MWCNTs and is expected to attach by Van der Walls bonds. Transmission electron microscopy and micro-Raman spectroscopy confirmed the crystalline nature of the hybrid structures. Electron emission studies were carried out using a diode-type field emission setup. The enhancement factor was found to be ~3,500 for bare MWCNTs, ~4,070 to ~5,000 for hybrid structures and ~6,500 for N-doped MLG-MWCNTs hybrid structures. Modification in the defects structure and enhancement of emission sites are suggested to be responsible for the increase of the field emission characteristics.

  20. ON THE EXTENDED EMISSION AROUND THE ANOMALOUS X-RAY PULSAR 1E 1547.0-5408

    SciTech Connect

    Olausen, S. A.; Kaspi, V. M.; Ng, C.-Y.; Zhu, W. W.; Dib, R. [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8 (Canada); Gavriil, F. P. [NASA Goddard Space Flight Center, Astrophysics Science Division, Code 662, Greenbelt, MD 20771 (United States); Woods, P. M. [Dynetics, Inc., 1000 Explorer Boulevard, Huntsville, AL 35806 (United States)

    2011-11-20

    We present an analysis of the extended emission around the anomalous X-ray pulsar 1E 1547.0-5408 using four XMM-Newton observations taken with the source in varying states of outburst as well as in quiescence. We find that the extended emission flux is highly variable and strongly correlated with the flux of the magnetar. Based on this result, as well as on spectral and energetic considerations, we conclude that the extended emission is dominated by a dust-scattering halo and not a pulsar wind nebula (PWN), as has been previously argued. We obtain an upper limit on the 2-10 keV flux of a possible PWN of 4.7 Multiplication-Sign 10{sup -14} erg s{sup -1} cm{sup -2}, three times less than the previously claimed value, implying an efficiency for conversion of spin-down energy into nebular luminosity of <9 Multiplication-Sign 10{sup -4} (assuming a distance of 4 kpc). We do, however, find strong evidence for X-ray emission from the supernova remnant shell surrounding the pulsar, as previously reported.

  1. Microwave observations of jupiter's synchrotron emission during the galileo flyby of amalthea in 2002.

    NASA Astrophysics Data System (ADS)

    Klein, M. J.; Bolton, S. J.; Bastian, T. S.; Blanc, M.; Levin, S. M.; McLeod, R. J.; MacLaren, D.; Roller, J. P.; Santos-Costa, D.; Sault, R.

    2003-04-01

    In November, 2002, the Galileo spacecraft trajectory provided a close flyby of Amalthea, one of Jupiter's inner most moons (˜2.4 RJ). During this pass, Galileo entered into a region rarely explored by spacecraft, the inner radiation belts of Jupiter. We present preliminary results from a campaign of microwave observations of Jovian synchrotron emission over a six month interval centered around the flyby. The observations were made with NASA's Deep Space Network (DSN) antennas at Goldstone, California, and the NRAO Very Large Array. We report preliminary measurements of the flux density of the synchrotron emission and the rotational beaming curves and a compare them with the long term history of Jupiter's microwave emission which varies significantly on timescales of months to years. The new data are also being examined to search for evidence of short-term variations and to compare single aperture beaming curves with the spatially resolved images obtained with the VLA. These radio astronomy data will be combined with in-situ measurements from Galileo (see companion paper by Bolton et al) to improve models of the synchrotron emission from Jupiter's radiation belts. A large percentage of the Goldstone observations were conducted by middle- and high school students from classrooms across the nation. The students and their teachers are participants in the Goldstone-Apple Valley Radio Telescope (GAVRT) science education project, which is a partnership involving NASA, the Jet Propulsion Laboratory and the Lewis Center for Educational Research (LCER) in Apple Valley, CA. Working with the Lewis Center over the Internet, GAVRT students conduct remotely controlled radio astronomy observations using 34-m antennas at Goldstone. The JPL contribution to this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration 2756 Planetary magnetospheres (5443, 5737, 6030) 6218 Jovian satellites 6220 Jupiter Planetary Sciences

  2. Microwave desolvation for acid sample introduction in inductively coupled plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Gras, Luis; Mora, Juan; Todolí, José L.; Canals, Antonio; Hernandis, Vicente

    1999-04-01

    This study deals with the behaviour of a microwave desolvation system (MWDS) with acid solutions in inductively coupled plasma atomic emission spectrometry. Hydrochloric, nitric, sulphuric and perchloric acids at different concentrations (up to 0.6 mol l -1) have been tested. Sample uptake rate ( Ql) was also varied. The parameters evaluated for each variable were analyte and solvent transport rates and emission intensity. The combination of low acid concentrations (0.05-0.1 mol l -1) and low liquid flows (0.4 ml min -1) leads to the highest analyte transport rate and emission signal and to the lowest solvent transport rate. For Ql higher than 1.9 ml min -1, the use of an impact bead is advisable. Among the acids tested, sulphuric and perchloric acids give rise to higher emission intensities than hydrochloric acid and nitric acid. Nonetheless, the limits of detection (LODs) obtained with the MWDS are about the same magnitude irrespective of the solution employed. The LODs reached when using the MWDS are similar to those obtained with a desolvation system based on infrared heating of the aerosol.

  3. An Alternative to Spinning Dust for the Microwave Emission of LPH 201.663+1.643: an Ultracompact HII Region

    E-print Network

    P. R. McCullough; R. R. Chen

    2002-01-17

    The microwave spectral energy distribution of the dusty, diffuse H II region LPH 201.663+1.643 has been interpreted by others as tentative evidence for microwave emission from spinning dust grains. We present an alternative interpretation for that particular object; specifically, that an ultracompact H II region embedded within the dust cloud would explain the available observations as well or better than spinning dust. Parameters for the size, surface brightness, and flux density of the putative ultracompact HII region, derived from the microwave observations, are within known ranges. A possible candidate for such an ultracompact H II region is IRAS 06337+1051, based upon its infrared colors. However, IRAS 06337+1051's infrared flux appears to be too small to be consistent with the microwave flux required for this alternative model to explain the observations.

  4. Constraints on the Emission and Viewing Geometry of the Transient Anomalous X-ray Pulsar XTE J1810-197

    NASA Technical Reports Server (NTRS)

    Perna, Rosalba; Gotthelf, E. V.

    2008-01-01

    The temporal decay of the flux components of the transient anomalous X-ray pulsar XTE J1 810-197 following its 2002 outburst presents a unique opportunity to probe the emission geometry of a magnetar. Toward this goal, we model the magnitude of the pulsar's modulation in narrow spectral bands over time. Following previous work, we assume that the postoutburst flux is produced in two distinct thermal components arising from a hot spot and a warm concentric ring. We include general relativistic effects on the blackbody spectra due to gravitational redshift and light bending near the stellar surface, which strongly depend on radius. This affects the model fits for the temperature and size of the emission regions. For the hot spot, the observed temporal and energy-dependent pulse modulation is found to require an anisotropic, pencil-beamed radiation pattern. We are able to constrain an allowed range for the angles that the line of sight (psi) and the hot spot pole (xi) make with respect to the spin axis. Within errors, this is defined by the locus of points in the xi-psi plane that lie along the line [xi + beta(R)] [psi + [beta(R)] = const, where beta(R) is a function of the radius R of the star. For a canonical value of R = 12 km, the viewing parameters range from psi = xi = 37deg to (psi, xi) = (85deg, 15deg). We discuss our results in the context of magnetar emission models.

  5. On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission

    E-print Network

    Butler, N R

    2006-01-01

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus extinction. Significant outliers to the population exist at the 5-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via detections of 2-5 lines: GRBs 060218, 060202, 050822, and 050714B. The most significant soft component detections in the full data set of ~2000 spectra correspond to GRB060218/SN2006aj, with significances ranging up to ~20sigma. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at ~solar abundance. We associate (>4sigma significant) line emission from the 3 other events with K-shell transitions in light metals. We favor a model where the line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor sta...

  6. Unique Properties of Thermally Tailored Copper: Magnetically Active Regions and Anomalous X-ray Fluorescence Emissions

    PubMed Central

    2009-01-01

    When high-purity copper (?99.98%wt) is melted, held in its liquid state for a few hours with iterative thermal cycling, then allowed to resolidify, the ingot surface is found to have many small regions that are magnetically active. X-ray fluorescence analysis of these regions exhibit remarkably intense lines from “sensitized elements” (SE), including in part or fully the contiguous series V, Cr, Mn, Fe, and Co. The XRF emissions from SE are far more intense than expected from known impurity levels. Comparison with blanks and standards show that the thermal “tailoring” also introduces strongly enhanced SE emissions in samples taken from the interior of the copper ingots. For some magnetic regions, the location as well as the SE emissions, although persistent, vary irregularly with time. Also, for some regions extraordinarily intense “sensitized iron” (SFe) emissions occur, accompanied by drastic attenuation of Cu emissions. PMID:20037657

  7. L-Band H Polarized Microwave Emission During the Corn Growth Cycle

    NASA Technical Reports Server (NTRS)

    Joseph, A. T.; va der Velde, R.; O'Neill, P. E.; Kim, E.; Lang, R. H.; Gish, T.

    2012-01-01

    Hourly L-band (1.4 GHz) horizontally (H) polarized brightness temperatures (T(sub B))'s measured during five episodes (more than two days of continuous measurements) of the 2002 corn growth cycle are analyzed. These T(sub B)'s measurements were acquired as a part of a combined active/passive microwave field campaign, and were obtained at five incidence and three azimuth angles relative to the row direction. In support of this microwave data collection, intensive ground sampling took place once a week. Moreover, the interpretation of the hourly T(sub B)'s could also rely on the data obtained using the various automated instruments installed in the same field. In this paper, the soil moisture and temperature measured at fixed time intervals have been employed as input for the tau-omega model to reproduce the hourly T(sub B). Through the calibration of the vegetation and surface roughness parameterizations, the impact of the vegetation morphological changes on the microwave emission and the dependence of the soil surface roughness parameter, h(sub r), on soil moisture are investigated. This analysis demonstrates that the b parameter, appearing in the representation of the canopy opacity, has an angular dependence that varies throughout the growing period and also that the parameter hr increases as the soil dries in a portion of the dry-down cycle. The angular dependence of the b parameter imposes the largest uncertainty on T(sub B) simulations near senescence as the response of b to the incidence is also affected by the crop row orientation. On the other hand, the incorporation of a soil moisture dependent h(sub r) parameterization was responsible for the largest error reduction of T(sub B) simulations in the early growth cycle.

  8. Iapetus' near surface thermal emission modeled and constrained using Cassini RADAR Radiometer microwave observations

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Leyrat, C.; Janssen, M. A.; Keihm, S.; Wye, L. C.; West, R.; Lorenz, R. D.; Tosi, F.

    2014-10-01

    Since its arrival at Saturn, the Cassini spacecraft has had only a few opportunities to observe Iapetus, Saturn's most distant regular satellite. These observations were all made from long ranges (>100,000 km) except on September 10, 2007, during Cassini orbit 49, when the spacecraft encountered the two-toned moon during its closest flyby so far. In this pass it collected spatially resolved data on the object's leading side, mainly over the equatorial dark terrains of Cassini Regio (CR). In this paper, we examine the radiometry data acquired by the Cassini RADAR during both this close-targeted flyby (referred to as IA49-3) and the distant Iapetus observations. In the RADAR's passive mode, the receiver functions as a radiometer to record the thermal emission from planetary surfaces at a wavelength of 2.2-cm. On the cold icy surfaces of Saturn's moons, the measured brightness temperatures depend both on the microwave emissivity and the physical temperature profile below the surface down to a depth that is likely to be tens of centimeters or even a few meters. Combined with the concurrent active data, passive measurements can shed light on the composition, structure and thermal properties of planetary regoliths and thus on the processes from which they have formed and evolved. The model we propose for Iapetus' microwave thermal emission is fitted to the IA49-3 observations and reveals that the thermal inertias sensed by the Cassini Radiometer over both CR and the bright mid-to-high latitude terrains, namely Ronceveaux Terra (RT) in the North and Saragossa Terra (ST) in the South, significantly exceed those measured by Cassini's CIRS (Composite Infrared Spectrometer), which is sensitive to much smaller depths, generally the first few millimeters of the surface. This implies that the subsurface of Iapetus sensed at 2.2-cm wavelength is more consolidated than the uppermost layers of the surface. In the case of CR, a thermal inertia of at least 50 J m-2 K-1 s-1/2, and most probably >200 J m-2 K-1 s-1/2 is inferred. This suggests a gradient in density with depth or, more likely, that the Radiometer has probed the icy substrate underlying the dark layer. Furthermore, the measured thermal emission is found to arise from the upper few meters of the subsurface, which points to tholins, rather than iron oxide compounds, as the primary contaminants of the dark material. We also find that, although there is a latitudinal decrease probably related to the thinning of the dark layer away from the Equator, the CR region exhibits a high 2.2-cm emissivity, 0.87 in average, which is close to the emissivity of Phoebe, a putative source of the dark matter. In the case of RT + ST, model fitting points to a mean thermal inertia of ?160 J m-2 K-1 s-1/2 along with the possible presence of an absorbing compound in the regolith of the bright terrains. Nevertheless, this layer is transparent enough for the Radiometer to capture the seasonal contrast between the northern and southern hemispheres. Lastly, a global decline of the microwave emissivity with latitude is revealed; it is probably indicative of a progressive increase of the water ice content in the near surface.

  9. Validation of microwave emission models by simulating AMSR-E brightness temperature data from ground-based observations

    Microsoft Academic Search

    Anna Kontu; Jouni Pulliainen; Pauli Heikkinen; Hanne Suokanerva; Matias Takala

    2007-01-01

    For several applications, spaceborne microwave measurements are used to get large scale information of snow- covered terrain. Emission models for soil, vegetation and snow are needed in extraction of snow parameters from satellite measurements. In this paper space-observed brightness temperature of snow-covered terrain is simulated from in situ measurements using HUT snow model, rough bare soil reflectivity model and boreal

  10. Gas temperature measurements in a microwave plasma by optical emission spectroscopy under single-wall carbon nanotube growth conditions

    Microsoft Academic Search

    R. K. Garg; T. N. Anderson; R. P. Lucht; T. S. Fisher; J. P. Gore

    2008-01-01

    Plasma gas temperatures were measured via in situ optical emission spectroscopy in a microwave CH4-H2 plasma under carbon nanotube (CNT) growth conditions. Gas temperature is an important parameter in controlling and optimizing CNT growth. The temperature has a significant impact on chemical kinetic rates, species concentrations and CNT growth rates on the substrate. H2 rotational temperatures were determined from the

  11. Gas temperature measurements in a microwave plasma by optical emission spectroscopy under single-wall carbon nanotube growth conditions

    Microsoft Academic Search

    R K Garg; T N Anderson; R P Lucht; T S Fisher; J P Gore

    2008-01-01

    Plasma gas temperatures were measured via in situ optical emission spectroscopy in a microwave CH4–H2 plasma under carbon nanotube (CNT) growth conditions. Gas temperature is an important parameter in controlling and optimizing CNT growth. The temperature has a significant impact on chemical kinetic rates, species concentrations and CNT growth rates on the substrate. H2 rotational temperatures were determined from the

  12. FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: GALACTIC FOREGROUND EMISSION

    SciTech Connect

    Gold, B.; Bennett, C. L.; Larson, D. [Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Hill, R. S.; Odegard, N.; Weiland, J. L. [Adnet Systems, Inc., 7515 Mission Dr., Suite A1C1 Lanham, Maryland 20706 (United States); Hinshaw, G.; Kogut, A.; Wollack, E. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Page, L.; Dunkley, J.; Jarosik, N. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Spergel, D. N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Komatsu, E. [Department of Astronomy, University of Texas, Austin, 2511 Speedway, RLM 15.306, Austin, TX 78712 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George St, University of Toronto, Toronto, ON M5S 3H8 (Canada); Wright, E. L. [PAB 3-909, UCLA Physics and Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States)], E-mail: bgold@pha.jhu.edu

    2009-02-15

    We present a new estimate of foreground emission in the Wilkinson Microwave Anisotropy Probe (WMAP) data, using a Markov chain Monte Carlo method. The new technique delivers maps of each foreground component for a variety of foreground models with estimates of the uncertainty of each foreground component, and it provides an overall goodness-of-fit estimate. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of the sky with a reduced {chi}{sup 2} {sub {nu}} of 1.14. However, the model does not work well inside the Galactic plane. The addition of either synchrotron steepening or a modified spinning dust model improves the fit. This component may account for up to 14% of the total flux at the Ka band (33 GHz). We find no evidence for foreground contamination of the cosmic microwave background temperature map in the 85% of the sky used for cosmological analysis.

  13. A comparison of radiative transfer models for predicting the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Choudhury, B. J.

    1980-01-01

    Two general types of numerical models for predicting microwave emission from soils are compared-coherent and noncoherent. In the former, radiation in the soil is treated coherently, and the boundary conditions on the electric fields across the layer boundaries are used to calculate the radiation intensity. In the latter, the radiation is assumed to be noncoherent, and the intensities of the radiation are considered directly. The results of the two approaches may be different because of the effects of interference, which can cause the transmitted intensity at the surface (i.e., emissivity) to be sometimes higher and sometimes lower for the coherent case than for the noncoherent case, depending on the relative phases of reflected fields from the lower layers. This coupling between soil layers in the coherent models leads to greater soil moisture sampling depths observed with this type of model, and is the major difference that is found between the two types of models. In noncoherent models, the emissivity is determined by the dielectric constraint at the air/soil interface. The subsequent differences in the results are functions of both the frequency of the radiation being considered and the steepness of the moisture gradient near the surface. The calculations were performed at frequencies of 1.4 and 19.4 GHz and for two sets of soil profiles. Little difference was observed between the models at 19.4 GHz; and only at the lower frequency were differences apparent because of the greater soil moisture sampling depth at this frequency.

  14. The DMRT-ML Model: Numerical Simulations of the Microwave Emission of Snowpacks Based on the Dense Media Radiative Transfer Theory

    NASA Technical Reports Server (NTRS)

    Brucker, Ludovic; Picard, Ghislain; Roy, Alexandre; Dupont, Florent; Fily, Michel; Royer, Alain

    2014-01-01

    Microwave radiometer observations have been used to retrieve snow depth and snow water equivalent on both land and sea ice, snow accumulation on ice sheets, melt events, snow temperature, and snow grain size. Modeling the microwave emission from snow and ice physical properties is crucial to improve the quality of these retrievals. It also is crucial to improve our understanding of the radiative transfer processes within the snow cover, and the snow properties most relevant in microwave remote sensing. Our objective is to present a recent microwave emission model and its validation. The model is named DMRT-ML (DMRT Multi-Layer), and is available at http:lgge.osug.frpicarddmrtml.

  15. The DMRT-ML Model: Numerical Simulations of the Microwave Emission of Snowpacks Based on the Dense Media Radiative Transfer Theory

    NASA Technical Reports Server (NTRS)

    Picard, Ghislain; Brucker, Ludovic; Roy, Alexandre; DuPont, FLorent; Champollion, Nicolas; Morin, Samuel

    2014-01-01

    Microwave radiometer observations have been used to retrieve snow depth and snow water equivalent on both land and sea ice, snow accumulation on ice sheets, melt events, snow temperature, and snow grain size. Modeling the microwave emission from snow and ice physical properties is crucial to improve the quality of these retrievals. It also is crucial to improve our understanding of the radiative transfer processes within the snow cover, and the snow properties most relevant in microwave remote sensing. Our objective is to present a recent microwave emission model and its validation. The model is named DMRT-ML (DMRT Multi-Layer).

  16. MASSIVE STAR FORMATION, OUTFLOWS, AND ANOMALOUS H{sub 2} EMISSION IN Mol 121 (IRAS 20188+3928)

    SciTech Connect

    Wolf-Chase, Grace; Arvidsson, Kim [Astronomy Department, Adler Planetarium, 1300 South Lake Shore Drive, Chicago, IL 60605 (United States)] [Astronomy Department, Adler Planetarium, 1300 South Lake Shore Drive, Chicago, IL 60605 (United States); Smutko, Michael [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)] [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Sherman, Reid, E-mail: gwolfchase@adlerplanetarium.org [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)] [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)

    2013-01-10

    We have discovered 12 new molecular hydrogen emission-line objects (MHOs) in the vicinity of the candidate massive young stellar object Mol 121, in addition to five that were previously known. H{sub 2} 2.12 {mu}m/H{sub 2} 2.25 {mu}m flux ratios indicate another region dominated by fluorescence from a photodissociation region, and one region that displays an anomalously low H{sub 2} 2.12 {mu}m/H{sub 2} 2.25 {mu}m flux ratio (<1) and coincides with a previously reported deeply embedded source (DES). Continuum observations at 3 mm reveal five dense cores; the brightest core is coincident with the DES. The next brightest cores are both associated with centimeter continuum emission. One of these is coincident with the IRAS source; the other lies at the centroid of a compact outflow defined by bipolar MHOs. The brighter of these bipolar MHOs exhibits [Fe II] emission and both MHOs are associated with CH{sub 3}OH maser emission observed at 95 GHz and 44 GHz. Masses and column densities of all five cores are consistent with theoretical predictions for massive star formation. Although it is impossible to associate all MHOs with driving sources in this region, it is evident that there are several outflows along different position angles, and some unambiguous associations can be made. We discuss implications of observed H{sub 2} 2.12 {mu}m/H{sub 2} 2.25 {mu}m and [Fe II] 1.64 {mu}m/H{sub 2} 2.12 {mu}m flux ratios and compare the estimated total H{sub 2} luminosity with the bolometric luminosity of the region. We conclude that the outflows are driven by massive young stellar objects embedded in cores that are likely to be in different evolutionary stages.

  17. Comparison among physical process based snow models in estimating SWE and upwelling microwave emission

    NASA Astrophysics Data System (ADS)

    Li, D.; Durand, M. T.; Margulis, S. A.

    2012-12-01

    Snowpack serves as a critical water resource and an important climate indicator. Accurately estimating snow water equivalent (SWE) and melt timing has both civil and scientific merits. Physical process based multi-layer land surface models (LSM) characterize snowpack by tracking the energy balance and mass balance in each layer. However, in terms of the number of layers used to model the snowpack stratigraphy, as well as the complexity of the simulated mass/energy exchanges in each single layer, significant variances exist among different LSMs. Previous work has largely focused on assessing the impact of layering and stratigraphy representation on mass and energy balance, with little attention paid to the implications of these factors on predicted microwave brightness temperature (Tb). In this paper, three LSMs with varying snow layer schemes: SSiB (3-layer), CoLM (5-layer), and SNOWPACK (N-layer), are coupled to the Microwave Emission from Multi-Layer Snowpacks (MEMLS) radiative transfer model (RTM) to simulate the snowpack mass/energy budgets and microwave signature over a full season. The simulations are performed at five in-situ gage locations in the Kern River Basin, Sierra Nevada, CA where it is known that large snow events occur that can be problematic to represent using a small number of snow layers. A particular emphasis is placed on assessment of the impact of layering scheme on the results. Preliminary results show that even for SSiB which has a relative simple empirical layering scheme, the modeled annual SWE could be highly correlated with the in-situ SWE (r¬2=0.91) if the precipitation bias is corrected, also, the comparison between the Tb simulated by SSiB+MEMLS and the downscaled AMSR-E Tb measurements shows a correlation coefficient of 0.94 during the snow accumulation season (Oct to Apr) if the grain growth parameters and the soil snow reflectivity is properly calibrated. Future work includes comparing SWE and Tb from all threemodels and quantitatively determining how the more complex models (SNOWPACK) could possibly further improve the Tb estimates, and how they will increase the computational loads, which are highly relevant to the ultimate goal of estimation of SWE via assimilation of multi-frequency passive microwave observations.

  18. Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: Implications for emission modeling

    NASA Astrophysics Data System (ADS)

    Rutter, Nick; Sandells, Mel; Derksen, Chris; Toose, Peter; Royer, Alain; Montpetit, Benoit; Langlois, Alex; Lemmetyinen, Juha; Pulliainen, Jouni

    2014-03-01

    Two-dimensional measurements of snowpack properties (stratigraphic layering, density, grain size, and temperature) were used as inputs to the multilayer Helsinki University of Technology (HUT) microwave emission model at a centimeter-scale horizontal resolution, across a 4.5 m transect of ground-based passive microwave radiometer footprints near Churchill, Manitoba, Canada. Snowpack stratigraphy was complex (between six and eight layers) with only three layers extending continuously throughout the length of the transect. Distributions of one-dimensional simulations, accurately representing complex stratigraphic layering, were evaluated using measured brightness temperatures. Large biases (36 to 68 K) between simulated and measured brightness temperatures were minimized (-0.5 to 0.6 K), within measurement accuracy, through application of grain scaling factors (2.6 to 5.3) at different combinations of frequencies, polarizations, and model extinction coefficients. Grain scaling factors compensated for uncertainty relating optical specific surface area to HUT effective grain size inputs and quantified relative differences in scattering and absorption properties of various extinction coefficients. The HUT model required accurate representation of ice lenses, particularly at horizontal polarization, and large grain scaling factors highlighted the need to consider microstructure beyond the size of individual grains. As variability of extinction coefficients was strongly influenced by the proportion of large (hoar) grains in a vertical profile, it is important to consider simulations from distributions of one-dimensional profiles rather than single profiles, especially in sub-Arctic snowpacks where stratigraphic variability can be high. Model sensitivity experiments suggested that the level of error in field measurements and the new methodological framework used to apply them in a snow emission model were satisfactory. Layer amalgamation showed that a three-layer representation of snowpack stratigraphy reduced the bias of a one-layer representation by about 50%.

  19. Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: implications for emission modelling

    NASA Astrophysics Data System (ADS)

    Sandells, M.; Rutter, N.; Derksen, C.; Langlois, A.; Lemmetyinen, J.; Montpetit, B.; Pulliainen, J. T.; Royer, A.; Toose, P.

    2012-12-01

    Remote sensing of snow mass remains a challenging area of research. Scattering of electromagnetic radiation is sensitive to snow mass, but is also affected by contrasts in the dielectric properties of the snow. Although the argument that errors from simple algorithms average out at large scales has been used to justify current retrieval methods, it is not obvious why this should be the case. This hypothesis needs to be tested more rigorously. A ground-based field experiment was carried out to assess the impact of sub-footprint snow heterogeneity on microwave brightness temperature, in Churchill, Canada in winter in early 2010. Passive microwave measurements of snow were made using sled-mounted radiometers at 75cm intervals over a 5m transect. Measurements were made at horizontal and vertical polarizations at frequencies of 19 and 37 GHz. Snow beneath the radiometer footprints was subsequently excavated, creating a snow trench wall along the centrepoints of adjacent footprints. The trench wall was carefully smoothed and photographed with a near-infrared camera in order to determine the positions of stratigraphic snow layer boundaries. Three one-dimensional vertical profiles of snowpack properties (density and snow specific surface area) were taken at 75cm, 185cm and 355cm from the left hand side of the trench. These profile measurements were used to derive snow density and grain size for each of the layers identified from the NIR image. Microwave brightness temperatures for the 2-dimensional map of snow properties was simulated with the Helsinki University of Technology (HUT) model at 1cm intervals horizontally across the trench. Where each of five ice lenses was identified in the snow stratigraphy, a decrease in brightness temperature was simulated. However, the median brightness temperature simulated across the trench was substantially higher than the observations, of the order of tens of Kelvin, dependent on frequency and polarization. In order to understand and quantify possible sources of error in the simulations, a number of experiments were carried out to investigate the sensitivity of the brightness temperature to: 1) uncertainties in field observations, 2) representation of ice lenses, 3) model layering structure, and 4) near-infrared derived grain size representing snow grain size at microwave wavelengths. Field measurement error made little difference to the simulated brightness temperature, nor did the representation of ice lenses as crusts of high density snow. As the number of layers in the snow was reduced to 3, 2, or 1, the simulated brightness temperature increased slightly. However, scaling of snow grain size had a dramatic effect on the simulated brightness temperatures, reducing the median bias of the simulations to within measurement error for the statistically different brightness temperature distributions. This indicated that further investigation is required to define what is meant by the microwave grain size, and how this relates to the grain size that is used in the microwave emission model.

  20. Microwave and hard X-ray emissions during the impulsive phase of solar flares: Nonthermal electron spectrum and time delay

    NASA Technical Reports Server (NTRS)

    Gu, Ye-Ming; Li, Chung-Sheng

    1986-01-01

    On the basis of the summing-up and analysis of the observations and theories about the impulsive microwave and hard X-ray bursts, the correlations between these two kinds of emissions were investigated. It is shown that it is only possible to explain the optically-thin microwave spectrum and its relations with the hard X-ray spectrum by means of the nonthermal source model. A simple nonthermal trap model in the mildly-relativistic case can consistently explain the main characteristics of the spectrum and the relative time delays.

  1. The Contribution of Galactic Free-Free Emission to Anistropies in the Cosmic Microwave Background Found by the Saskatoon Experiment

    NASA Astrophysics Data System (ADS)

    Simonetti, John H.; Dennison, Brian; Topasna, Gregory A.

    1996-02-01

    We made a sensitive, wide-field H alpha image of the north celestial polar region. Using this image, we constrain the contribution of irregularities in interstellar free-free emission to the degree-scale anisotropies in the cosmic microwave background detected in recent observations at Saskatoon by the Princeton group. The analysis of the H alpha image mimics the Saskatoon data analysis: the resulting signal is the strength of irregularities sampled with the Saskatoon beam (i.e., degree-scale) along the 85 deg declination circle. We found no such irregularities that could be attributed to H alpha emission. The implied upper bound on the rms variation in free-free brightness temperature is less than 4.6 mu K at 27.5 GHz. The observed cosmic microwave background anisotropies are much larger. Therefore, the contribution of irregularities in interstellar free-free emission to the observed anisotropies is negligible.

  2. On the Early Time X-ray Spectra of Swift Afterglows I: Evidence for Anomalous Soft X-ray Emission

    E-print Network

    Nathaniel R. Butler

    2006-11-03

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~10^7s. We find that most afterglows are consistent with pure power-laws plus extinction. Significant outliers to the population exist at the 5-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible detections of 2-5 lines: GRBs 060218, 060202, 050822, and 050714B. Alternatively, a blackbody model with kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most significant soft component detections in the full data set of ~2000 spectra correspond to GRB060218/SN2006aj, with line significances ranging up to \\~20-sigma. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at ~ solar abundance. We associate (>4-sigma significant) line triggers in the 3 other events with K-shell transitions in light metals. We favor a model where the possible line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor star. The emitting material in each burst is at a similar distance \\~10^12--10^13 cm, a similar density ~10^17 cm^-3, and subject to a similar flux of ionizing radiation. The lines may correlate with the X-ray flaring. For the blackbody interpretation, the soft flux may arise from break out of the GRB shock or plasma cocoon from the progenitor stellar wind, as recently suggested for GRB060218 (Campana et al. 2006). Due to the low z of GRB060218, bursts faint in Gamma-rays with fluxes dominated by this soft X-ray component could outnumber classical GRBs 100-1.

  3. On the Anomalous Silicate Emission Features of AGNs: A Possible Interpretation Based on Porous Dust

    E-print Network

    M. P. Li; Q. J. Shi; Aigen Li

    2008-08-29

    The recent Spitzer detections of the 9.7 micron Si--O silicate emission in type 1 AGNs provide support for the AGN unification scheme. The properties of the silicate dust are of key importance to understanding the physical, chemical and evolutionary properties of the obscuring dusty torus around AGNs. Compared to that of the Galactic interstellar medium (ISM), the 10 micron silicate emission profile of type 1 AGNs is broadened and has a clear shift of peak position to longer wavelengths. In literature this is generally interpreted as an indication of the deviations of the silicate composition, size, and degree of crystallization of AGNs from that of the Galactic ISM. In this Letter we show that the observed peak shift and profile broadening of the 9.7 micron silicate emission feature can be explained in terms of porous composite dust consisting of ordinary interstellar amorphous silicate, amorphous carbon and vacuum. Porous dust is naturally expected in the dense circumnuclear region around AGNs, as a consequence of grain coagulation.

  4. Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Galactic Foreground Emission

    NASA Astrophysics Data System (ADS)

    Gold, B.; Odegard, N.; Weiland, J. L.; Hill, R. S.; Kogut, A.; Bennett, C. L.; Hinshaw, G.; Chen, X.; Dunkley, J.; Halpern, M.; Jarosik, N.; Komatsu, E.; Larson, D.; Limon, M.; Meyer, S. S.; Nolta, M. R.; Page, L.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.; Wollack, E.; Wright, E. L.

    2011-02-01

    We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of the updated (KQ85y7) foreground mask. We place a 15 ?K upper bound on rms foreground contamination in the cleaned maps used for cosmological analysis. Further, the cleaning process requires only three power-law foregrounds outside of the mask. We find no evidence for polarized foregrounds beyond those from soft (steep-spectrum) synchrotron and thermal dust emission; in particular we find no indication in the polarization data of an extra "haze" of hard synchrotron emission from energetic electrons near the Galactic center. We provide an updated map of the cosmic microwave background (CMB) using the internal linear combination method, updated foreground masks, and updates to point source catalogs using two different techniques. With additional years of data, we now detect 471 point sources using a five-band technique and 417 sources using a three-band CMB-free technique. In total there are 62 newly detected point sources, a 12% increase over the five-year release. Also new are tests of the Markov chain Monte Carlo foreground fitting procedure against systematics in the time-stream data, and tests against the observed beam asymmetry. Within a few degrees of the Galactic plane, the behavior in total intensity of low-frequency foregrounds is complicated and not completely understood. WMAP data show a rapidly steepening spectrum from 20 to 40 GHz, which may be due to emission from spinning dust grains, steepening synchrotron, or other effects. Comparisons are made to a 1 deg 408 MHz map (Haslam et al.) and the 11 deg ARCADE 2 data (Singal et al.). We find that spinning dust or steepening synchrotron models fit the combination of WMAP and 408 MHz data equally well. ARCADE data appear inconsistent with the steepening synchrotron model and consistent with the spinning dust model, though some discrepancies remain regarding the relative strength of spinning dust emission. More high-resolution data in the 10-40 GHz range would shed much light on these issues. WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

  5. Possible evidence for dark matter annihilations from the excess microwave emission around the center of the Galaxy seen by the Wilkinson Microwave Anisotropy Probe

    NASA Astrophysics Data System (ADS)

    Hooper, Dan; Finkbeiner, Douglas P.; Dobler, Gregory

    2007-10-01

    The Wilkinson Microwave Anisotropy Probe (WMAP) experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. It has been suggested that this signal, known as the “WMAP haze,” could be synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. In this article, we revisit this possibility. We find that the angular distribution of the WMAP haze matches the prediction for dark matter annihilations with a cusped density profile, ?(r)?r-1.2 in the inner kiloparsecs. Comparing the intensity in different WMAP frequency bands, we find that a wide range of possible weakly interacting massive particle (WIMP) annihilation modes are consistent with the spectrum of the haze for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, ?v˜3×10-26cm3/s. No boost factors are required. If dark matter annihilations are in fact responsible for the WMAP haze, and the slope of the halo profile continues into the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter annihilations in the galactic center if the WIMP mass is less than several hundred GeV.

  6. Analytical Evaluation of a Reduced-Pressure Microwave-Induced Plasma Studied by Optical Emission Spectrometry Method

    Microsoft Academic Search

    Henryk Matusiewicz; Mariusz Slachcinski

    2011-01-01

    The authors describe a system that utilizes a reduced-pressure (RP) air-cooled microwave-induced plasma (MIP) torch to interface an ultrasonic nebulizer (USN) with an optical emission spectrometer (OES). Argon was investigated as plasma gas. The analytical potential of such techniques was illustrated for the determination of elements. A univariate approach and simplex optimization procedure was used to achieve optimized conditions and

  7. Optical Emission Characteristics of Atmospheric-Pressure Nonequilibrium Microwave Discharge and High-Frequency DC Pulse Discharge Plasma Jets

    Microsoft Academic Search

    Toshifumi Yuji; Shuitsu Fujii; Narong Mungkung; Hiroshi Akatsuka

    2009-01-01

    With an aim to understand the mechanism of surface processing by atmospheric-pressure nonequilibrium discharge plasma jets, we measured the vibrational and rotational temperatures in the plasmas by means of optical emission spectroscopy (OES) measurement method. This paper focuses on the OES measurement method using a torch-shaped atmospheric-pressure nonequilibrium discharge plasma jet power supply consisting of a microwave (2.45-GHz) generator and

  8. Microwave emission and beam propagation measurements in a high-power relativistic electron beam-plasma system

    Microsoft Academic Search

    M. S. Di Capua; J. F. Camacho; E. S. Fulkerson; D. Meeker

    1988-01-01

    Microwave emission was measured from a system consisting of an unmagnetized plasma and a propagating electron beam. A 93-cm2 velvet cathode, with an anode-cathode gap of 5.9 cm, injects the electron current into the plasma through an aluminized Mylar anode. Measurements were made of the diode voltage and current in the 6-?V water dielectric accelerator and net current through the

  9. Modeling microwave backscatter and thermal emission from linear dune fields: Application to Titan

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Janssen, M. A.; Kirk, R. L.; Lorenz, R. D.

    2014-02-01

    We present an electromagnetic model that relates the microwave backscatter and thermal emission from linear dune fields to their compositional, physical (roughness, subsurface porosity/heterogeneity) and geometrical (slope, orientation) properties. This model shows the value of exploring these highly directional and geometrical features in light of both their backscattering cross-section and emissivity. Compared to Cassini concurrent radar and radiometry data acquired from October 2004 to June 2011 over Titan's dune fields, it provides clues to understand variations among dune regions on the largest Saturn's moon. In particular, it brings a formal support to the idea first advanced in Le Gall et al. (Le Gall, A., Janssen, M.A., Wye, L.C., Hayes, A.G., Radebaugh, J., Savage, C., Zebker, H., Lorenz, R.D., Lunine, J.I., Kirk, R.L., Lopes, R.M.C., Wall, S., Callahan, P., Stofan, E.R., Farr, T. and the Cassini Radar Team [2011]. Icarus 213, 608-624) that the size of the interdune valleys (relative to that of the dunes) varies across Titan as well as the diffuse scattering properties of these interdune areas due to different thickness of sand cover (i.e. bedrock contribution) or degree of compaction/heterogeneity of the sand cover. The Fensal and Belet dune fields, in particular, are quite different in terms of these properties. The comparison between the model and Cassini data also reveals the potential presence of structures, possibly small-superposed dunes, oriented perpendicular to the dune crests in the Aztlan region.

  10. Effects of varying soil moisture contents and vegetation canopies on microwave emissions

    NASA Technical Reports Server (NTRS)

    Burke, H.-H. K.; Schmugge, T. J.

    1982-01-01

    Results of NASA airborne passive microwave scans of bare and vegetated fields for comparison with ground truth tests are discussed and a model for atmospheric scattering of radiation by vegetation is detailed. On-board radiometers obtained data at 21, 2.8, and 1.67 cm during three passes over each of 46 fields, 28 of which were bare and the others having wheat or alfalfa. Ground-based sampling included moisture in five layers down to 15 cm in addition to soil temperature. The relationships among the brightness temperature and soil moisture, as well as the surface roughness and the vegetation canopy were examined. A model was developed for the dielectric coefficient and volume scattering for a vegetation medium. L- to C-band data were found useful for retrieving soil information directly. A surface moisture content of 5-35% yielded an emissivity of 0.9-0.7. The data agreed well with a combined multilayer radiative transfer model with simple roughness correction.

  11. Ozone-stimulated emission due to atomic oxygen population inversions in an argon microwave plasma torch

    SciTech Connect

    Lukina, N. A.; Sergeichev, K. F. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)

    2008-06-15

    It is shown that, in a microwave torch discharge in an argon jet injected into an oxygen atmosphere at normal pressure, quasi-resonant energy transfer from metastable argon atoms to molecules of oxygen and ozone generated in the torch shell and, then, to oxygen atoms produced via the dissociation of molecular oxygen and ozone leads to the inverse population of metastable levels of atomic oxygen. As a result, the excited atomic oxygen with population inversions becomes a gain medium for lasing at wavelengths of 844.6 and 777.3 nm (the 3{sup 3}P-3{sup 3}S and 3{sup 5}P-3{sup 5}S transitions). It is shown that an increase in the ozone density is accompanied by an increase in both the lasing efficiency at these wavelength and the emission intensity of the plasma-forming argon at a wavelength of 811.15 nm (the {sup 2}P{sup 0}4s-{sup 2}P{sup 0}4p transition). When the torch operates unstably, the production of singlet oxygen suppresses ozone generation; as a result, the lasing effect at these wavelengths disappears.

  12. MICROWAVE EMISSION FROM THE EDGEWORTH-KUIPER BELT AND THE ASTEROID BELT CONSTRAINED FROM THE WILKINSON MICROWAVE ANISOTROPY PROBE

    SciTech Connect

    Ichikawa, Kazuhide; Fukugita, Masataka [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)

    2011-08-01

    Objects in the Edgeworth-Kuiper Belt and the main asteroid belt should emit microwaves that may give rise to extra anisotropy signals in the multipole of the cosmic microwave background (CMB) experiment. Constraints are derived from the absence of positive detection of such anisotropies for l {approx}< 50, meaning the total mass of Edgeworth-Kuiper Belt objects is smaller than 0.2 M{sub +}. This limit is consistent with the mass extrapolated from the observable population with the size of a {approx}> 15 km, assuming that the small-object population follows the power law in size dN/da {approx} a{sup -q} with the canonical index expected for collisional equilibrium, q {approx_equal} 3.5, with which 23% of the mass is ascribed to objects smaller than are observationally accessible down to grains. A similar argument applied to the main asteroid belt indicates that the grain population should not increase more quickly than q {approx_equal} 3.6 toward smaller radii, if the grain population follows the power law that continues to observed asteroids with larger radii. Both cases are at or only slightly above the limit that can be physically significant, implying the importance of further tightening the CMB anisotropy limit, which may be attained with observation at higher radio frequencies.

  13. The Cosmic Microwave Background Temperature and Galactic Emission at 8.0 and 8.3 GHz

    NASA Astrophysics Data System (ADS)

    Singal, J.; Fixsen, D. J.; Kogut, A.; Levin, S.; Limon, M.; Lubin, P.; Mirel, P.; Seiffert, M.; Wollack, E. J.

    2006-12-01

    We report balloon-borne measurements at 8.0 and 8.3 GHz of Galactic emission and of the radiometric temperature of the cosmic microwave background, the results from the first flight of the ARCADE 2 (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission) instrument. We find the Galactic free-free emission intensity in the plane to be two-thirds as high as that predicted by a naive extrapolation of 2003 WMAP K-band data, a result consistent with 2006 WMAP findings, and find the Galactic synchrotron emission intensity to be approximately as high as that predicted by a naive interpolation of Haslam all-sky survey and WMAP K-band data. We find TCMB to be 2.90+/-0.12 K at 8.0 GHz and 2.77+/-0.16 K at 8.3 GHz.

  14. Microwave absorption properties and infrared emissivities of ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework

    SciTech Connect

    Wang, Tao [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); He, Jianping, E-mail: jianph@nuaa.edu.c [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhou, Jianhua; Tang, Jing; Guo, Yunxia; Ding, Xiaochun; Wu, Shichao; Zhao, Jianqing [College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2010-12-15

    Ordered mesoporous C-TiO{sub 2} nanocomposites with crystalline framework were prepared by the evaporation-induced triconstituent co-assembly method. The products were characterized by XRD, TEM, N{sub 2} adsorption-desorption and TG. Their microwave absorption properties were investigated by mixing the product and epoxy resin. It is found that the peak with minimum reflection loss value moves to lower frequencies and the ordered mesoporous C-TiO{sub 2} nanocomposite possesses an excellent microwave absorbing property with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. The attenuation of microwave can be attributed to dielectric loss and their absorption mechanism is discussed in detail. The mesoporous C-TiO{sub 2} nanocomposites also exhibit a lower infrared emissivity in the wavelength from 8 to 14 {mu}m than that of TiO{sub 2}-free powder. -- Graphical abstract: Ordered mesoporous C-TiO{sub 2} nanocomposite with crystalline framework possess excellent microwave absorbing properties with the maximum reflection loss of -25.4 dB and the bandwidth lower than -10 dB is 6.6 GHz. Display Omitted

  15. Signal Analysis of Microwave Radiometric Emissions in Hurricanes: Part 2 - Oceanic Rain Rate Dependence

    Microsoft Academic Search

    Ruba Akram Amarin; James Johnson; W. Linwood Jones

    2006-01-01

    Communications technologies contribute significantly to environmental remote sensing. In fact, microwave remote sensing of surface wind speed and rain rate in hurricanes is critical to the numerical hurricane forecasting capability. The stepped frequency microwave radiometer, SFMR, is a C-band remote sensing instrument that is routinely flown into hurricanes by NOAA to measure surface wind speed and rain rate. This paper

  16. Anomalous Changes of Diffuse Hydrogen Emission from Poás Volcano, Costa Rica, Central America: a Premonitory Geochemical Signature of Volcanic Unrest?

    NASA Astrophysics Data System (ADS)

    Melián, G.; Galindo, I.; Salazar, J. M.; Pérez, N. M.; Hernández, P. A.; Fernández, M.; Ramírez, C.; Mora, R.; Alvarado, G.

    2002-12-01

    Poás volcano is a large basaltic-andesite stratovolcano located of the Cordillera Central in Costa Rica. The summit of Poás consists of three nested calderas and an active crater located between two older cones: Von Frantzius to the north and Botos cone to the south. This active crater contains a hot and acidic crater lake, and host an active hydrothermal system. The purpose of this work is to study and evaluate the spatial distribution of diffuse H2 at the surface environment of Poás volcano during the period 2000-2002. Diffuse H2 degassing surveys have been yearly performed at Poás volcano since the year 2000 covering an area of 3.4 Km2. Soil gas H2 concentration ranged from 0.6 to 4.1 ppmV, from 0.4 to 1,910.3 ppmV, and from 0.8 to 7,059.2 ppmV for the 2000, 2001 and 2002 surveys, respectively. Statistical-graphical analysis was applied for the soil gas H2 concentration data observed for three surveys. Two populations were observed for the 2000 survey, while three were observed for 2001 and 2002 surveys. Most of the study area showed background soil gas H2 concentrations for the 2000 (0.6 ppmV), 2001 (0.7 ppmV), and 2002 (4.1 ppmV) surveys. Peak mean values of soil gas H2 content were just observed for the 2001 (15.2 ppmV) and 2002 (340.1 ppmV) surveys. Peak soil gas H2 concentration values were mainly observed inside the main crater, but the anomalous H2 area for the 2002 survey is larger than the 2001 survey. These data suggest an increasing trend of soil gas H2 concentration at Poás. The observed secular variation of the spatial distribution of diffuse H2 emission was closely related to fumarole activity changes inside the main crater during the last three years. These results might suggest that diffuse H2 emission could be a premonitory geochemical signature of volcanic unrest at Poás.

  17. Ultralow field emission from thinned, open-ended, and defected carbon nanotubes by using microwave hydrogen plasma processing

    NASA Astrophysics Data System (ADS)

    Deng, Jian-Hua; Cheng, Lin; Wang, Fan-Jie; Yu, Bin; Li, Guo-Zheng; Li, De-Jun; Cheng, Guo-An

    2015-01-01

    Ultralow field emission is achieved from carbon nanotubes (CNTs) by using microwave hydrogen plasma processing. After the processing, typical capped CNT tips are removed, with thinned, open-ended, and defected CNTs left. Structural analyses indicate that the processed CNTs have more SP3-hybridized defects as compared to the pristine ones. The morphology of CNTs can be readily controlled by adjusting microwave powers, which change the shape of CNTs by means of hydrogen plasma etching. Processed CNTs with optimal morphology are found to have an ultralow turn-on field of 0.566 V/?m and threshold field of 0.896 V/?m, much better than 0.948 and 1.559 V/?m of the as-grown CNTs, respectively. This improved FE performance is ascribed to the structural changes of CNTs after the processing. The thinned and open-ended shape of CNTs can facilitate electron tunneling through barriers and additionally, the increased defects at tube walls can serve as new active emission sites. Furthermore, our plasma processed CNTs exhibit excellent field emission stability at a large emission current density of 10.36 mA/cm2 after being perfectly aged, showing promising prospects in applications as high-performance vacuum electron sources.

  18. The microwave emissivity variability of snow covered first-year sea ice from late winter to early summer: a model study

    NASA Astrophysics Data System (ADS)

    Willmes, S.; Nicolaus, M.; Haas, C.

    2013-12-01

    Satellite observations of microwave brightness temperatures between 19 GHz and 85 GHz are the main data source for operational sea-ice monitoring. However, the sea ice microwave emissivity is subject to pronounced seasonal variations and shows significant hemispheric contrasts that mainly arise from differences in the rate and strength of snow metamorphism and melt. We use the thermodynamic snow model SNTHERM and the microwave emission model MEMLS to identify the contribution of regional patterns in atmospheric energy fluxes to surface emissivity variations on Arctic and Antarctic sea ice between 2000 and 2009. The obtained emissivity data reveal a pronounced seasonal cycle with a large regional variability. The emissivity variability increases from winter to early summer and is more pronounced in the Antarctic. In the pre-melt period (January-May, July-November) the variations in surface microwave emissivity due to diurnal, regional and inter-annual variability of atmospheric forcing reach up to 3.4%, 4.3%, and 9.7% for 19 GHz, 37 GHz and 85 GHz channels, respectively. Small but significant emissivity trends can be observed in the Weddell Sea during November and December as well as in Fram Strait during February. The obtained emissivity data lend themselves for an assessment of sea-ice concentration and snow-depth algorithm accuracies.

  19. Coupling the snow thermodynamic model SNOWPACK with the microwave emission model of layered snowpacks for subarctic and arctic snow water equivalent retrievals

    NASA Astrophysics Data System (ADS)

    Langlois, A.; Royer, A.; Derksen, C.; Montpetit, B.; Dupont, F.; GoïTa, K.

    2012-12-01

    Satellite-passive microwave remote sensing has been extensively used to estimate snow water equivalent (SWE) in northern regions. Although passive microwave sensors operate independent of solar illumination and the lower frequencies are independent of atmospheric conditions, the coarse spatial resolution introduces uncertainties to SWE retrievals due to the surface heterogeneity within individual pixels. In this article, we investigate the coupling of a thermodynamic multilayered snow model with a passive microwave emission model. Results show that the snow model itself provides poor SWE simulations when compared to field measurements from two major field campaigns. Coupling the snow and microwave emission models with successive iterations to correct the influence of snow grain size and density significantly improves SWE simulations. This method was further validated using an additional independent data set, which also showed significant improvement using the two-step iteration method compared to standalone simulations with the snow model.

  20. A large scale microwave emission model for forests. Contribution to the SMOS algorithm

    NASA Astrophysics Data System (ADS)

    Rahmoune, R.; Della Vecchia, A.; Ferrazzoli, P.; Guerriero, L.; Martin-Porqueras, F.

    2009-04-01

    1. INTRODUCTION It is well known that surface soil moisture plays an important role in the water cycle and the global climate. SMOS is a L-Band multi-angle dual-polarization microwave radiometer for global monitoring of this variable. In the areas covered by forests, the opacity is relatively high, and the knowledge of moisture remains problematic. A significant percentage of SMOS pixels at global scale is affected by fractional forest. Whereas the effect of the vegetation can be corrected thanks a simple radiative model, in case of dense forests the wave penetration is limited and the sensitivity to variations of soil moisture is poor. However, most of the pixels are mixed, and a reliable estimate of forest emissivity is important to retrieve the soil moisture of the areas less affected by forest cover. Moreover, there are many sparse woodlands, where the sensitivity to variations of soil moisture is still acceptable. At the scale of spaceborne radiometers, it is difficult to have a detailed knowledge of the variables which affect the overall emissivity. In order to manage effectively these problems, the electromagnetic model developed at Tor Vergata University was combined with information available from forest literature. Using allometric equations and other information, the geometrical and dielectric inputs required by the model were related to global variables available at large scale, such as the Leaf Area Index. This procedure is necessarily approximate. In a first version of the model, forest variables were assumed to be constant in time, and were simply related to the maximum yearly value of Leaf Area Index. Moreover, a unique sparse distribution of trunk diameters was assumed. Finally, the temperature distribution within the crown canopy was assumed to be uniform. The model is being refined, in order to consider seasonal variations of foliage cover, subdivided into arboreous foliage and understory contributions. Different distributions of trunk diameter are being considered. Also the effects of temperature gradients within the crown canopy are being considered. The model was tested against radiometric measurements carried out by towers and aircrafts. A new test has been done using the brightness temperatures measured over some forests in Finland by the AMIRAS radiometer, which is an airborne demonstrator of the MIRAS imaging radiometer to be launched with SMOS. The outputs produced by the model are used to fit the parameters of the simple radiative transfer model which will be used in the Level 2 soil moisture retrieval algorithm. It is planned to compare model outputs with L1C data, which will be made available during the commissioning phase. To this end, a number of adequate extended forest sites are being selected: the Amazon rain forest, the Zaire Basins, the Argentinian Chaco forest, and the Finland forest. 2. PARAMETRIC STUDIES In this paper, results of parametric simulations are shown. The emissivity at vertical and horizontal polarization is simulated as a function of soil moisture content for various conditions of forest cover. Seasonal effects are considered, and the values of Leaf Area Index in winter and summer are taken as basic inputs. The difference between the two values is attributed partially to arboreous foliage and partially to understory, while the woody biomass is assumed to be constant in time. Results indicate that seasonal effects are limited, but not negligible. The simulations are repeated for different distributions of trunk diameters. If the distributions is centered over lower diameter values, the forest is optically thicker, for a given biomass. Also the variations of brightness temperature due to a temperature gradient within the crown canopy have been estimated. The outputs are used to predict the values of a simple first order RT model. 3. COMPARISONS WITH EXPERIMENTAL DATA Results of previous comparisons between model simulations and experimental data are summarized. Experimental data were collected by tower, in the Julich and Les Landes forest (Bray site) and by aircraft, ove

  1. Optical emission spectroscopy for simultaneous measurement of plasma electron density and temperature in a low-pressure microwave induced plasma

    SciTech Connect

    Konjevic, N. [Institute of Physics, University of Belgrade, P.O. Box 68, Belgrade 11081 (Serbia); Faculty of Physics, University of Belgrade, P.O. Box 368, Belgrade 11001 (Serbia); Jovicevic, S.; Ivkovic, M. [Institute of Physics, University of Belgrade, P.O. Box 68, Belgrade 11081 (Serbia)

    2009-10-15

    The simple optical emission spectroscopy technique for diagnostics of low pressure microwave induced plasma (MIP) in hydrogen or in MIP seeded with hydrogen is described and tested. This technique uses the Boltzmann plot of relative line intensities along Balmer spectral series in conjunction with the criterion for partial local thermodynamic equilibrium for low electron density (N{sub e}) plasma diagnostics. The proposed technique is tested in a low pressure MIP discharge for simultaneous determination of electron density N{sub e} (10{sup 17}-10{sup 18} m{sup -3}) and temperature T{sub e}.

  2. Microwave remediation of electronic circuitry waste and the resulting gaseous emissions

    NASA Astrophysics Data System (ADS)

    Schulz, Rebecca L.

    The global community has become increasingly dependent on computer and electronic technology. As a result, society is faced with an increasing amount of obsolete equipment and electronic circuitry waste. Electronic waste is generally disposed of in landfills. While convenient, this action causes a substantial loss of finite resources and poses an environmental threat as the circuit board components breakdown and are exposed to the elements. Hazardous compounds such as lead, mercury and cadmium may leach from the circuitry and find their way into the groundwater supply. For this dissertation, a microwave waste remediation system was developed. The system was designed to remove the organic components from a wide variety of electronic circuitry. Upon additional heating of the resulting ash material in an industrial microwave, a glass and metal product can be recovered. Analysis of the metal reveals the presence of precious metals (gold, silver) that can be sold to provide a return on investment. a glass and metal product can be recovered. Analysis of the metal reveals the presence of precious metals (gold, silver) that can be sold to provide a return on investment. Gaseous organic compounds that were generated as a result of organic removal were treated in a microwave off gas system that effectively reduced the concentration of the products emitted by several orders of magnitude, and in some cases completely destroying the waste gas. Upon further heating in an industrial microwave, a glass and metal product were recovered. In order to better understand the effects of processing parameters on the efficiency of the off-gas system, a parametric study was developed. The study tested the microwave system at 3 flow rates (10, 30, and 50 ft 3/min) and three temperatures (400, 700 and 1000°C. In order to test the effects of microwave energy, the experiments were repeated using a conventional furnace. While microwave energy is widely used, the mechanisms of interaction with materials is not well understood. In an effort to better understand how microwaves couple with materials, a newly developed molecular orbital model was investigated. The model proposed an interaction mechanism associated with the development of coupled oscillators upon application of microwave energy. The model was used to model several of the waste gases that appear in the waste stream. Results from experimentation support the data generated thus far.

  3. Evaluation of the effects of varying moisture contents on microwave thermal emissions from agriculture fields

    NASA Technical Reports Server (NTRS)

    Burke, H. H. K.

    1980-01-01

    Three tasks related to soil moisture sensing at microwave wavelengths were undertaken: (1) analysis of data at L, X and K sub 21 band wavelengths over bare and vegetated fields from the 1975 NASA sponsored flight experiment over Phoenix, Arizona; (2) modeling of vegetation canopy at microwave wavelengths taking into consideration both absorption and volume scattering effects; and (3) investigation of overall atmospheric effects at microwave wavelengths that can affect soil moisture retrieval. Data for both bare and vegetated fields are found to agree well with theoretical estimates. It is observed that the retrieval of surface and near surface soil moisture information is feasible through multi-spectral and multi-temporal analysis. It is also established that at long wavelengths, which are optimal for surface sensing, atmospheric effects are generally minimal. At shorter wavelengths, which are optimal for atmosheric retrieval, the background surface properties are also established.

  4. Attenuation of soil microwave emissivity by corn and soybeans at 1.4 and 5 GHz

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; O'Neill, Peggy E.

    1989-01-01

    Theory and experiments have shown that passive microwave radiometers can be used to measure soil moisture. However, the presence of a vegetative cover alters the measurement that might be obtained under bare conditions. Deterministically accounting for the effect of vegetation and developing algorithms for extracting soil moisture from observations of a vegetable-soil complex present significant obstacles to the practical use of this approach. The presence of a vegetation canopy reduces the sensitivity of passive microwave instruments to soil moisture variations. The reduction in sensitivity, as compared to a bare-soil relationship, increases as microwave frequency increases, implying that the longest wavelength sensors should provide the most information. Sensitivity also decreases as the amount of vegetative wet biomass increases for a given type of vegetation.

  5. Publicly Available Numerical Codes for Modeling the X-ray and Microwave Emissions from Solar and Stellar Activity

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Mariska, John T.; McTiernan, James M.; Ofman, Leon; Petrosian, Vahe; Ramaty, Reuven; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have posted numerical codes on the Web for modeling the bremsstrahlung x-ray emission and the a gyrosynchrotron radio emission from solar and stellar activity. In addition to radiation codes, steady-state and time-dependent Fokker-Planck codes are provided for computing the distribution and evolution of accelerated electrons. A 1-D hydrodynamics code computes the response of the stellar atmosphere (chromospheric evaporation). A code for modeling gamma-ray line spectra is also available. On-line documentation is provided for each code. These codes have been developed for modeling results from the High Energy Solar Spectroscopic Imager (HESSI) along related microwave observations of solar flares. Comprehensive codes for modeling images and spectra of solar flares are under development. The posted codes can be obtained on NASA/Goddard's HESSI Web Site at http://hesperia.gsfc.nasa.gov/hessi/modelware.htm. This work is supported in part by the NASA Sun-Earth Connection Program.

  6. Secondary-electron-emission properties of conducting surfaces with application to multistage depressed collectors for microwave amplifiers

    NASA Technical Reports Server (NTRS)

    Forman, R.

    1977-01-01

    To improve the efficiency of high power microwave tubes, low secondary electron yield electrode surface for use in depressed collectors are needed. The secondary emission characteristics of a number of materials were investigated. The materials studied were beryllium, carbon (soot and pyrolytic graphite), copper, titanium carbide, and tantalum. Both total secondary yield delta and relative reflected primary yield were measured. These measurements were made in conjunction with Auger spectroscopy so that the secondary emission characteristics could be determined as a function of surface contamination or purity. The results show that low atomic weight elements, such as beryllium and carbon, have the lowest reflected primary yield and that roughening the surface of an electrode can markedly decrease secondary yield both for delta and reflected primaries. All factors considered, a roughened pyrolytic graphite surface showed the greatest potential for use as an electrode surface in depressed collectors.

  7. Field emission from bias-grown diamond thin films in a microwave plasma

    DOEpatents

    Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (Naperville, IL); Ding, Ming Q. (Beijing, CN); Auciello, Orlando (Bolinbrook, IL)

    2002-01-01

    A method of producing diamond or diamond like films in which a negative bias is established on a substrate with an electrically conductive surface in a microwave plasma chemical vapor deposition system. The atmosphere that is subjected to microwave energy includes a source of carbon, nitrogen and hydrogen. The negative bias is maintained on the substrate through both the nucleation and growth phase of the film until the film is continuous. Biases between -100V and -200 are preferred. Carbon sources may be one or more of CH.sub.4, C.sub.2 H.sub.2 other hydrocarbons and fullerenes.

  8. The Contribution of Galactic Free-Free Emission to Anisotropies in the Cosmic Microwave Background Radiation Measured by MSAM

    NASA Astrophysics Data System (ADS)

    Simonetti, J. H.; Topasna, G. A.; Dennison, B.

    1996-05-01

    The Medium Scale Anisotropy Measurement (MSAM) experiment has detected anisotropies in the cosmic microwave background radiation with an rms between about 30 mu K and 90 mu K. MSAM uses double-difference and single-difference demodulation signals from a chopped, 30(') beam at a number of frequencies between 170 and 680 GHz. We observed the region covered by MSAM using the Virginia Tech Spectral Line Imaging Camera (SLIC), a wide-field camera sensitive to faint interstellar H? emission. We duplicated the MSAM chopping and demodulation procedure using samples from our H? image (after the subtraction of a continuum image and smoothing to a 30(') beam). The rms in our double-difference and single-difference demodulation signals are 4.4 and 3.0 Rayleighs, respectively. The implied rms for the microwave brightness temperature of the interstellar plasma is <1 mu K at 170 GHz. Thus the MSAM anisotropies are not significantly contaminated by foreground Galactic emission irregularities. This research was supported by NSF grant AST-9319670 and a grant from the Horton Foundation to Virginia Tech.

  9. Multielement Analysis of Food by Microwave Digestion and Inductively Coupled Plasma-Atomic Emission Spectrometry

    Microsoft Academic Search

    Scott P. Dolan; Stephen G. Capar

    2002-01-01

    A microwave digestion procedure for multi-elemental analysis of food was developed using one program to digest a variety of food matrices at the same time. A single program was enabled by an analytical portion mass based on the food's energy content calculated from macronutrient data (fat, protein and carbohydrate). The procedure allows a maximum mass to be analyzed for each

  10. Microwave emission from high Arctic Sea ice during freeze-up

    Microsoft Academic Search

    J. P. Hollinger; B. E. Troy; R. O. Ramseier; K. W. Asmus; M. F. Hartman; C. A. Luther

    1984-01-01

    A cooperative sea ice remote sensing experiment was conducted in the eastern Beaufort Sea and Mould Bay area during the freeze-up period in October 1981. Airborne millimeter-wave imagery at 90, 140, and 220 GHz, and nadir microwave radiometric measurements at 19, 22, and 31 GHz, were made from a U. S. Naval Research Laboratory aircraft, while the Canadian Atmospheric Environmental

  11. Microwave Radiometer (MWR) Handbook

    SciTech Connect

    Morris, VR

    2006-08-01

    The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

  12. The effect of wind on the microwave emission from the ocean's surface at 37 GHz

    NASA Technical Reports Server (NTRS)

    Wilheit, T. T.

    1978-01-01

    The microwave brightness temperature measurements from the Electrically Scanned Microwave Radiometer (frequency = 37 GHz) are compared with oceanic wind measurements from data buoys. It is shown that the brightness temperature can be manipulated to yield a measure of the surface roughening which can be very well accounted for by a simple geometric optics model. The data of 1.4, 8.36 and 19.34 GHz were similarly manipulated and shown to require a surface with less slope variance than predicted by optical measurements. It is also shown that the surface may be treated as isotropic to an accuracy equivalent to the roughening produced by a 2 m/s wind speed increment.

  13. Fast polarization changes in mm microwave emission of weak multistructured solar bursts

    NASA Technical Reports Server (NTRS)

    Kaufmann, P.; Strauss, F. M.; Costa, J. E. R.; Dennis, B. R.

    1982-01-01

    Circular polarization of weak multistructured solar bursts was measured at mm microwaves with unprecedented sensitivity (0.03 sfu rms) and high time resolution (1ms). It was shown that sudden changes occur in the degree of polarization with time scales of 0.04 to 0.3 s. In most cases the degree of polarization attained maximum values before the maximum flux in both mm microwaves and hard X-rays with time scales of 0.04 to 1.0 s. The timing accuracy in determining the degree of polarization was 40 ms. Physical phenomena are discussed invoking one or a combination of various possible causes for the observed effects. The bursts at mm microwaves were weak compared to the contribution of the preexisting active regions, and therefore the changes in magnetoionic propagation conditions for emerging radiation plays an important role in the observed effects. Composite effects due to more than one polarizing mechanism or more than one polarized spots within the antenna beam are discussed.

  14. Influence of (FeO + TiO2) abundance on the thermal emission from the lunar regolith using Chang'E-2 microwave radiometer data

    NASA Astrophysics Data System (ADS)

    Meng, Zhiguo; Ping, Jinsong; Xu, Yi; Cai, Zhanchuan; Zheng, Yongchun

    Abstract?The microwave radiometer data obtained from Chang’E-2 mission (CELMS data) has provided new opportunity to study the influence of the (FeO+TiO2) abundance on the microwave thermal emission of the lunar regolith. In this paper, the radiative transfer simulation is employed to study the change of the brightness temperature with (FeO+TiO2) abundance at different frequencies and surface temperature. The (FeO+TiO2) abundance are derived from Clementine UV-VIS data and the samples from Apollo, Luna and Surveyor projects. The simulation results along the Equator indicate that the (FeO+TiO2) abundance has strong impact on the microwave thermal emission of the lunar regolith. However, the data along the Longitude 0° shows that the (FeO+TiO2) abundance is not the dominant influential factor of the microwave thermal emission of the lunar regolith. Specifically, the abnormal brightness temperature at 160°W (Unnamed crater), 138°W (Crater Vavilov), 125°W (Crater Hertzsprung), 116°E (Crater Abul Wáfa), 119°E (Crater Heron), 130°E (Crater Catena Gregory) and 140°E (Crater Catena Mendeleev) shows that the (FeO+TiO2) abundance is not the only influential factor for the observed brightness temperature. In addition, the correlations between the four-channel brightness temperature and the (FeO+TiO2) abundance in Apollo landing site and along the Equator both indicate that the (FeO+TiO2) abundance is slightly decreasing with depth. The research is essential for the inversion of the lunar regolith parameters with the microwave radiometer data from Chang’E satellites. Keywords: lunar regolith, microwave thermal emission, CELMS data, (FeO+TiO2) abundance

  15. Design of red/green emissive lanthanide activated nano-materials by supersonic and microwave co-irradiations

    NASA Astrophysics Data System (ADS)

    Wang, Qianming; Huo, Jiansheng; Zheng, Yuhui; Pang, Shuting; He, Zhouzhi

    2013-04-01

    ZnSnO3:Eu3+ and Sr1-xCaxMoO4:Tb3+ nanocrystals with controlled shape have been assembled in the presence of two driving forces (supersonic microwave co-assistance, abbreviated as SMC) simultaneously in less than 60 min at very low temperature (80 °C). Scanning Electronic Microscope (SEM) images further supported the existence of cubic crystals and shuttle-like structures. More interestingly, Eu(III) ion has been encapsulated into zinc stannate for the first time and ZnSnO3:Eu3+ can exhibit red emissions excited by long wavelength (395 nm). Similarly, it was found that Sr1-xCaxMoO4:Tb3+ had striking green luminescence. The parameters to improve the optical properties have been studied in detail. This convenient approach may be applicable to construct other phosphors with well-defined crystalline structures.

  16. Plasma Upflows and Microwave Emission in Hot Supra-arcade Structure Associated with an M1.6 Limb Flare

    NASA Astrophysics Data System (ADS)

    Kim, S.; Shibasaki, K.; Bain, H.-M.; Cho, K.-S.

    2014-04-01

    We have investigated a supra-arcade structure associated with an M1.6 flare, which occurred on the south-east limb on 2010 November 4. It is observed in EUV with the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, microwaves at 17 and 34 GHz with the Nobeyama Radioheliograph (NoRH), and soft X-rays of 8-20 keV with RHESSI. Interestingly, we found exceptional properties of the supra-arcade thermal plasma from the AIA 131 Å and the NoRH: (1) plasma upflows along large coronal loops and (2) enhancing microwave emission. RHESSI detected two soft X-ray sources, a broad one in the middle of the supra-arcade structure and a bright one just above the flare-arcade. We estimated the number density and thermal energy for these two source regions during the decay phase of the flare. In the supra-arcade source, we found that there were increases of the thermal energy and the density at the early and last stages, respectively. On the contrary, the density and thermal energy of the source on the top of the flare-arcade decreases throughout. The observed upflows imply that there is continuous energy supply into the supra-arcade structure from below during the decay phase of the flare. It is hard to explain by the standard flare model in which the energy release site is located high in the corona. Thus, we suggest that a potential candidate of the energy source for the hot supra-arcade structure is the flare-arcade, which has exhibited a predominant emission throughout.

  17. The microwave emissivity variability of snow covered first-year sea ice from late winter to early summer: a model study

    NASA Astrophysics Data System (ADS)

    Willmes, S.; Nicolaus, M.; Haas, C.

    2014-05-01

    Satellite observations of microwave brightness temperatures between 19 GHz and 85 GHz are the main data sources for operational sea-ice monitoring and retrieval of ice concentrations. However, microwave brightness temperatures depend on the emissivity of snow and ice, which is subject to pronounced seasonal variations and shows significant hemispheric contrasts. These mainly arise from differences in the rate and strength of snow metamorphism and melt. We here use the thermodynamic snow model SNTHERM forced by European Re-Analysis (ERA) interim data and the Microwave Emission Model of Layered Snowpacks (MEMLS), to calculate the sea-ice surface emissivity and to identify the contribution of regional patterns in atmospheric conditions to its variability in the Arctic and Antarctic. The computed emissivities reveal a pronounced seasonal cycle with large regional variability. The emissivity variability increases from winter to early summer and is more pronounced in the Antarctic. In the pre-melt period (January-May, July-November) the standard deviations in surface microwave emissivity due to diurnal, regional and inter-annual variability of atmospheric forcing reach up to ?? = 0.034, 0.043, and 0.097 for 19 GHz, 37 GHz and 85 GHz channels, respectively. Between 2000 and 2009, small but significant positive emissivity trends were observed in the Weddell Sea during November and December as well as in Fram Strait during February, potentially related to earlier melt onset in these regions. The obtained results contribute to a better understanding of the uncertainty and variability of sea-ice concentration and snow-depth retrievals in regions of high sea-ice concentrations.

  18. Detection of microwave emission due to rock fracture as a new tool for geophysics: A field test at a volcano in Miyake Island, Japan

    NASA Astrophysics Data System (ADS)

    Takano, Tadashi; Maeda, Takashi; Miki, Yoji; Akatsuka, Sayo; Hattori, Katsumi; Nishihashi, Masahide; Kaida, Daishi; Hirano, Takuya

    2013-07-01

    This paper describes a field test to verify a newly discovered phenomenon of microwave emission due to rock fracture in a volcano. The field test was carried out on Miyake Island, 150 km south of Tokyo. The main objective of the test was to investigate the applicability of the phenomenon to the study of geophysics, volcanology, and seismology by extending observations of this phenomenological occurrence from the laboratory to the natural field. We installed measuring systems for 300 MHz, 2 GHz, and 18 GHz-bands on the mountain top and mountain foot in order to discriminate local events from regional and global events. The systems include deliberate data subsystems that store slowly sampled data in the long term, and fast sampled data when triggered. We successfully obtained data from January to February 2008. During this period, characteristic microwave pulses were intermittently detected at 300 MHz. Two photographs taken before and after this period revealed that a considerably large-scale collapse occurred on the crater cliff. Moreover, seismograms obtained by nearby observatories strongly suggest that the crater subsidence occurred simultaneously with microwave signals on the same day during the observation period. For confirmation of the microwave emission caused by rock fracture, these microwave signals must be clearly discriminated from noise, interferences, and other disturbances. We carefully discriminated the microwave data taken at the mountaintop and foot, checked the lightning strike data around the island, and consequently concluded that these microwave signals could not be attributed to lightning. Artificial interferences were discriminated by the nature of their waveforms. Thus, we inferred that the signals detected at 300 MHz were due to rock fractures during cliff collapses. This result may provide a useful new tool for geoscientists and for the mitigation of natural hazards.

  19. Microwave emission from snow and glacier ice. [brightness temperature for snow fields

    NASA Technical Reports Server (NTRS)

    Chang, T. C.; Gloersen, P.; Schmugge, T.; Wilheit, T. T.; Zwally, H. J.

    1975-01-01

    The microwave brightness temperature for snow fields was studied assuming that the snow cover consists of closely packed scattering spheres which do not interact coherently. The Mie scattering theory was used to compute the volume scattering albedo. It is shown that in the wavelength range from 0.8 to 2.8 cm, most of the micro-radiation emanates from a layer 10 meters or less in thickness. It is concluded that it is possible to determine snow accumulation rates as well as near-surface temperature.

  20. Optical emission spectroscopy of microwave-plasmas at atmospheric pressure applied to the growth of organosilicon and organotitanium nanopowders

    SciTech Connect

    Kilicaslan, A.; Levasseur, O.; Roy-Garofano, V.; Profili, J.; Moisan, M.; Stafford, L., E-mail: luc.stafford@umontreal.ca [Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada); Côté, C.; Sarkissian, A. [Plasmionique Inc., Varennes, Québec J3X 1S2 (Canada)

    2014-03-21

    An atmospheric-pressure plasma sustained by an electromagnetic surface wave (SW) in the microwave regime combined with a bubbler/flash evaporator for the injection of liquid precursors was used to produce organosilicon and organotitanium nanopowders. Following the addition of hexamethyldisiloxane (HMDSO) vapors in the nominally pure argon plasma, optical emission spectra revealed the apparition of strong C{sub 2} molecular bands along with Si and Balmer H emission lines. Such features were not observed in our atmospheric-pressure Ar/HMDSO discharges controlled by dielectric barriers, indicating that microwave plasmas are characterized by much higher fragmentation levels of the precursors due to much higher electron densities. Emission spectra from the Ar/HMDSO SW plasma further showed a high-intensity continuum, the intensity of which decreased with time as powders started to form on the discharge tube walls. In presence of titanium isopropoxide (TTIP) vapors in the nominally pure Ar plasma, the emission was dominated by Ar and Ti lines, with no trace of carbon and no continuum. Fourier-Transform Infrared (FTIR) Spectroscopy of the powders formed in Ar/HMDSO plasmas showed very strong Si-(CH{sub 3}){sub x} and O-Si-(CH{sub 3}){sub x} bands, which is consistent with the formation of silicon oxycarbide. Transmission Electron Microscopy (TEM) further showed tube and sheet-like nanofeatures as well as larger structures consisting of agglomerated primary clusters. On the other hand, introduction of O{sub 2} in Ar/HMDSO plasmas produced only round-like nanoparticles with strong Si-O-Si bands and no trace of carbon, consistent with the formation of SiO{sub x}. The average size of the silica nanoparticles was 50?nm. FTIR spectra of powders formed in Ar/TTIP plasmas showed strong Ti-O signals, even without the addition of O{sub 2} in the gas phase. Corresponding TEM analysis showed nano- and agglomerated features comparable to those obtained in Ar/HMDSO although the average size of the titanate nanoparticles was smaller (10?nm). This set of data indicates that SW plasmas represent a promising parametric tool not only to achieve nanopowders with tailored properties for applications, but also for fundamental studies of nanodusty plasmas at atmospheric-pressure.

  1. Optical emission spectroscopy of microwave-plasmas at atmospheric pressure applied to the growth of organosilicon and organotitanium nanopowders

    NASA Astrophysics Data System (ADS)

    Kilicaslan, A.; Levasseur, O.; Roy-Garofano, V.; Profili, J.; Moisan, M.; Côté, C.; Sarkissian, A.; Stafford, L.

    2014-03-01

    An atmospheric-pressure plasma sustained by an electromagnetic surface wave (SW) in the microwave regime combined with a bubbler/flash evaporator for the injection of liquid precursors was used to produce organosilicon and organotitanium nanopowders. Following the addition of hexamethyldisiloxane (HMDSO) vapors in the nominally pure argon plasma, optical emission spectra revealed the apparition of strong C2 molecular bands along with Si and Balmer H emission lines. Such features were not observed in our atmospheric-pressure Ar/HMDSO discharges controlled by dielectric barriers, indicating that microwave plasmas are characterized by much higher fragmentation levels of the precursors due to much higher electron densities. Emission spectra from the Ar/HMDSO SW plasma further showed a high-intensity continuum, the intensity of which decreased with time as powders started to form on the discharge tube walls. In presence of titanium isopropoxide (TTIP) vapors in the nominally pure Ar plasma, the emission was dominated by Ar and Ti lines, with no trace of carbon and no continuum. Fourier-Transform Infrared (FTIR) Spectroscopy of the powders formed in Ar/HMDSO plasmas showed very strong Si-(CH3)x and O-Si-(CH3)x bands, which is consistent with the formation of silicon oxycarbide. Transmission Electron Microscopy (TEM) further showed tube and sheet-like nanofeatures as well as larger structures consisting of agglomerated primary clusters. On the other hand, introduction of O2 in Ar/HMDSO plasmas produced only round-like nanoparticles with strong Si-O-Si bands and no trace of carbon, consistent with the formation of SiOx. The average size of the silica nanoparticles was 50 nm. FTIR spectra of powders formed in Ar/TTIP plasmas showed strong Ti-O signals, even without the addition of O2 in the gas phase. Corresponding TEM analysis showed nano- and agglomerated features comparable to those obtained in Ar/HMDSO although the average size of the titanate nanoparticles was smaller (10 nm). This set of data indicates that SW plasmas represent a promising parametric tool not only to achieve nanopowders with tailored properties for applications, but also for fundamental studies of nanodusty plasmas at atmospheric-pressure.

  2. Anomalous green emission and energy transfer in the n,n-dimethylformamide/hydrochloric acid/europium chloride system.

    PubMed

    Dimitriev, O P; Kislyuk, V V

    2005-03-24

    The unusual green photoluminescence (PL) of N,N-dimethylformamide (DMF)/hydrochloric acid (HCl)/europium chloride (EuCl3) solutions discovered earlier was investigated in more detail to clarify the emission mechanism. It was revealed that the DMF/HCl pair alone can yield a green PL band under UV excitation, and the emission has features of that of excimers. The addition of EuCl3 salt to the solution further stimulates the green emission. The quantum yield of the line emission of Eu3+ ions at 592 and 612 nm is also affected by the presence of HCl in the solution. Both the green emission band and Eu3+ emission lines possess a common channel of excitation at approximately 280 nm. This channel is the only source for the green emission band and an additional source for the Eu3+ emission lines, which can also be stimulated through a conventional Eu3+ excitation channel at 394 nm. The common excitation channel was found to be time-dependent, and its excitation maximum gradually shifts to longer wavelengths. Changes in the PL profiles of europium ions were also observed depending on the presence of HCl and the solution aging. PMID:16833546

  3. Research relative to angular distribution of snow reflectance/snow cover characterization and microwave emission

    NASA Technical Reports Server (NTRS)

    Dozier, Jeff; Davis, Robert E.

    1987-01-01

    Remote sensing has been applied in recent years to monitoring snow cover properties for applications in hydrologic and energy balance modeling. In addition, snow cover has been recently shown to exert a considerable local influence on weather variables. Of particular importance is the potential of sensors to provide data on the physical properties of snow with high spatial and temporal resolution. Visible and near-infrared measurements of upwelling radiance can be used to infer near-surface properties through the calculation of albedo. Microwave signals usually come from deeper within the snow pack and thus provide depth-integrated information, which can be measured through clouds and does not relay on solar illumination.Fundamental studies examining the influence of snow properties on signals from various parts of the electromagnetic spectrum continue in part because of the promise of new remote sensors with higher spectral and spatial accuracy. Information in the visible and near-infrared parts of the spectrum comprise nearly all available data with high spatial resolution. Current passive microwave sensors have poor spatial resolution and the data are problematic where the scenes consist of mixed landscape features, but they offer timely observations that are independent of cloud cover and solar illumination.

  4. Differential Microlensing of the Continuum and Broad Emission Lines in SDSS J0924+0219, the Most Anomalous Lensed Quasar

    Microsoft Academic Search

    Charles R. Keeton; Scott Burles; Paul L. Schechter; Joachim Wambsganss

    2005-01-01

    SDSS J0924+0219 is the most glaring example of a gravitational lens with\\u000aanomalous flux ratios: optical broad-band photometry shows image D to be a\\u000afactor of 12 fainter than expected for smooth lens potentials. We report\\u000aspectroscopy showing that the anomaly is present in the broad emission line\\u000aflux ratios as well. There are differences between the emission line and

  5. On the effect of cyclotron emission on the spectral distortions of the cosmic microwave background

    E-print Network

    Andrea Zizzo; Carlo Burigana

    2005-05-12

    We have investigated the role of the cyclotron emission associated to cosmic magnetic fields on the evolution of CMB spectral distortions by considering the contributions by spontaneous and stimulated emission and by absorption in the computation of the photon and energy injection rates. These cyclotron emission rates have been numerically compared with those of the relevant radiative processes operating in the cosmic plasma, bremsstrahlung and double Compton scattering, for realistic CMB distorted spectra at early and late epochs. For reasonable magnetic field strengths we find that the cyclotron emission contribution is much smaller than the bremsstrahlung and double Compton contributions, because of their different frequency locations and the high bremsstrahlung and double Compton efficiency to keep the long wavelength region of the CMB spectrum close to a blackbody (at electron temperature) during the formation of the spectral distortion. Differently from previous analyses, we find that for a very large set of dissipation mechanisms the role of cyclotron emission in the evolution of CMB spectral distortions is negligible and, in particular, it cannot re-establish a blackbody spectrum after the generation of a realistic early distortion. The constraints on the energy exchanges at various cosmic times can be then derived, under quite general assumptions, by considering only Compton scattering, bremsstrahlung, and double Compton, other than, obviously, the considered dissipation process. Finally, upper limits to the CMB polarization degree induced by cyclotron emission have been estimated.

  6. Miniaturized dielectric barrier discharge carbon atomic emission spectrometry with online microwave-assisted oxidation for determination of total organic carbon.

    PubMed

    Han, Bingjun; Jiang, Xiaoming; Hou, Xiandeng; Zheng, Chengbin

    2014-07-01

    A simple, rapid, and portable system consisted of a laboratory-built miniaturized dielectric barrier discharge atomic emission spectrometer and a microwave-assisted persulfate oxidation reactor was developed for sensitive flow injection analysis or continuous monitoring of total organic carbon (TOC) in environmental water samples. The standard/sample solution together with persulfate was pumped to the reactor to convert organic compounds to CO2, which was separated from liquid phase and transported to the spectrometer for detection of the elemental specific carbon atomic emission at 193.0 nm. The experimental parameters were systematically investigated. A limit of detection of 0.01 mg L(-1) (as C) was obtained based on a 10 mL sample injection volume, and the precision was better than 6.5% (relative standard deviation, RSD) at 0.1 mg L(-1). The system was successfully applied for TOC analysis of real environmental water samples. The obtained TOC value of 30 test samples agreed well with those by the standard high-temperature combustion coupled nondispersive infrared absorption method. Most importantly, the system showed good capability of in situ continuous monitoring of total organic carbon in environmental water. PMID:24862626

  7. Preparation, Infrared Emissivity, and Dielectric and Microwave Absorption Properties of Fe-Doped ZnO Powder

    NASA Astrophysics Data System (ADS)

    Su, Xiaolei; Jia, Yan; Liu, Xiaoqin; Wang, Junbo; Xu, Jie; He, Xinhai; Fu, Chong; Liu, Songtao

    2014-11-01

    Fe-doped ZnO powders have been synthesized by the coprecipitation method using zinc nitrate [Zn(NO3)2·6H2O] as starting material, urea [CO(NH2)2] as precipitator, and ferric nitrate [Fe(NO3)3·9H2O] as doping source. The microstructure of the prepared powders has been characterized by x-ray diffraction and scanning electron microscopy. Results show that, when the molar ratio of Fe to (Zn + Fe) was less than 0.09, the prepared powder was ZnO(Fe) solid solution, and the ZnFe2O4 impurity phase appeared when the Fe doping content was further increased. The electric permittivity in the frequency range of 8.2 GHz to 12.4 GHz and the average infrared emissivity in the wavelength range of 8 ?m to 14 ?m have been determined for the prepared powders. The average infrared emissivity decreased with increasing Fe doping content. The real ( ?') and imaginary part ( ??) of the permittivity of the prepared powders showed opposite trends. When the molar ratio of Fe to (Zn + Fe) was 0.03, the prepared Fe-doped ZnO powder demonstrated the best microwave absorption in the frequency range of 8.2 GHz to 12.4 GHz.

  8. Evidence of Convective Redistribution of Carbon Monoxide in Aura Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) Observations

    NASA Technical Reports Server (NTRS)

    Manyin, Michael; Douglass, Anne; Schoeberl, Mark

    2010-01-01

    Vertical convective transport is a key element of the tropospheric circulation. Convection lofts air from the boundary layer into the free troposphere, allowing surface emissions to travel much further, and altering the rate of chemical processes such as ozone production. This study uses satellite observations to focus on the convective transport of CO from the boundary layer to the mid and upper troposphere. Our hypothesis is that strong convection associated with high rain rate regions leads to a correlation between mid level and upper level CO amounts. We first test this hypothesis using the Global Modeling Initiative (GMI) chemistry and transport model. We find the correlation is robust and increases as the precipitation rate (the strength of convection) increases. We next examine three years of CO profiles from the Tropospheric Emission Sounder (TES) and Microwave Limb Sounder (MLS) instruments aboard EOS Aura. Rain rates are taken from the Tropical Rainfall Measuring Mission (TRMM) 3B-42 multi-satellite product. Again we find a correlation between mid-level and upper tropospheric CO, which increases with rain rate. Our result shows the critical importance of tropical convection in coupling vertical levels of the troposphere in the transport of trace gases. The effect is seen most clearly in strong convective regions such as the Inter-tropical Convergence Zone.

  9. Asymmetric absorption and emission of energy by a macroscopic mechanical oscillator in a microwave circuit optomechanical system

    NASA Astrophysics Data System (ADS)

    Harlow, Jennifer; Palomaki, Tauno; Kerckhoff, Joseph; Teufel, John; Simmonds, Raymond; Lehnert, Konrad

    2012-02-01

    We measure the asymmetry in rates for emission and absorption of mechanical energy in an electromechanical system composed of a macroscopic suspended membrane coupled to a high-Q, superconducting microwave resonant circuit. This asymmetry is inherently quantum mechanical because it arises from the inability to annihilate the mechanical ground state. As such, it is only appreciable when the average mechanical occupancy approaches one. This measurement is now possible due to the recent achievement of ground state cooling of macroscopic mechanical oscillators [1,2]. Crucially, we measure the thermal cavity photon occupancy and account for it in our analysis. Failure to correctly account for the interference of these thermal photons with the mechanical signal can lead to a misinterpretation of the data and an overestimate of the emission/absorption asymmetry. [4pt] [1] J. D. Teufel, T. Donner, Dale Li, J. W. Harlow, M. S. Allman, K. Cicak, A. J. Sirois, J. D. Whittaker, K. W. Lehnert, R. W. Simmonds, ``Sideband Cooling Micromechanical Motion to the Quantum Ground State,'' Nature, 475, 359-363 (2011).[0pt] [2] Jasper Chan, et al, ``Laser cooling of a nanomechanical oscillator into its quantum ground state,'' Nature, 478, 89-92 (2011).

  10. Thermal microwave emission from vegetated fields - A comparison between theory and experiment

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Shiue, J. C.; Dombrowski, M.; Chuang, S. L.; Shin, R. T.

    1984-01-01

    The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4- and 5-GHz microwave radiometers during August-October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two-layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature T sub B than that expected from a bare soil. The amount of this T sub B excess increases with increase in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations, which include a parameter characterizing ground surface roughness, generally match well with the experimental data.

  11. Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop

    E-print Network

    Kuznetsov, Alexey; Reznikova, Veronika

    2015-01-01

    Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by magnetohydrodynamic (MHD) oscillations of flaring loops which modulate the emission. Interpretation of the observations requires comparing them with simulations. We simulate the gyrosynchrotron radio emission from a semi-circular (toroidal-shaped) magnetic loop containing sausage-mode MHD oscillations. The aim is to detect the observable signatures specific to the considered MHD mode and to study their dependence on the various source parameters. The MHD waves are simulated using a linear three-dimensional model of a magnetized plasma cylinder; both standing and propagating waves are considered. The curved loop is formed by replicating the MHD solutions along the plasma cylinder and bending the cylinder; this model allows us to study the effect of varying the viewing angle along the loop. The radio emission is simulated using a three-dimensional model and its spatial a...

  12. Calibration of the Model for Ocean Surface Emissivity at Microwave Frequencies Sandra L. Cruz Pol

    E-print Network

    Ruf, Christopher

    @ktb.ee.psu.edu Abstract -- Modifications to the Klein and Swift [1] model for specular ocean emissivity have recently been presented here tests both the original and modified models using a set of satellite and ground based observations (RaObs) coincident with TOPEX satellite overpasses were used to reduce errors due to inexact

  13. THE EFFECT OF DEW ON THE MICROWAVE EMISSION OF MAIZE AT L-BAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dew has the net effect of decreasing the brightness temperature of maize at L-band. Scattering is enhanced more than emission. This effect occurs at both polarizations, but vertically-polarized brightness is affected more than horizontally-polarized brightness. As more water condenses on the cano...

  14. Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. A.; Van Doorsselaere, T.; Reznikova, V. E.

    2015-03-01

    Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by magnetohydrodynamic (MHD) oscillations of flaring loops which modulate the emission. Interpreting the observations requires comparing them with simulations. We simulated the gyrosynchrotron radio emission from a semicircular (toroidal-shaped) magnetic loop containing sausage-mode MHD oscillations. The aim was to detect the observable signatures specific to the considered MHD mode and to study their dependence on the various source parameters. The MHD waves were simulated using a linear three-dimensional model of a magnetized plasma cylinder; both standing and propagating waves were considered. The curved loop was formed by replicating the MHD solutions along the plasma cylinder and bending the cylinder; this model allowed us to study the effect of varying the viewing angle along the loop. The radio emission was simulated using a three-dimensional model, and its spatial and temporal variations were analyzed. We considered several loop orientations and different parameters of the magnetic field, plasma, and energetic electrons in the loop. In the model with low plasma density, the intensity oscillations at all frequencies are synchronous (with the exception of a narrow spectral region below the spectral peak). In the model with high plasma density, the emission at low frequencies (where the Razin effect is important) oscillates in anti-phase with the emissions at higher frequencies. The oscillations at high and low frequencies are more pronounced in different parts of the loop (depending on the loop orientation). The layers where the line-of-sight component of the magnetic field changes sign can produce additional peculiarities in the oscillation patterns.

  15. Connecting Surface Emissions, Convective Uplifting, and Long-Range Transport of Carbon Monoxide in the Upper Troposphere: New Observations from the Aura Microwave Limb Sounder

    NASA Technical Reports Server (NTRS)

    Jiang, Jonathan H.; Livesey, Nathaniel J.; Su, Hui; Neary, Lori; McConnell, John C.; Richards, Nigel A. D.

    2007-01-01

    Two years of observations of upper tropospheric (UT) carbon monoxide (CO) from the Aura Microwave Limb Sounder are analyzed; in combination with the CO surface emission climatology and data from the NCEP analyses. It is shown that spatial distribution, temporal variation and long-range transport of UT CO are closely related to the surface emissions, deep-convection and horizontal winds. Over the Asian monsoon region, surface emission of CO peaks in boreal spring due to high biomass burning in addition to anthropogenic emission. However, the UT CO peaks in summer when convection is strongest and surface emission of CO is dominated by anthropogenic source. The long-range transport of CO from Southeast Asia across the Pacific to North America, which occurs most frequently during boreal summer, is thus a clear imprint of Asian anthropogenic pollution influencing global air quality.

  16. On the Early-Time X-Ray Spectra of Swift Afterglows. I. Evidence for Anomalous Soft X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Butler, N. R.

    2007-02-01

    We have conducted a thorough and blind search for emission lines in >70 Swift X-ray afterglows of total exposure ~107 s. We find that most afterglows are consistent with pure power laws plus extinction. Significant outliers to the population exist at the 5%-10% level and have anomalously soft, possibly thermal spectra. Four bursts are singled out via possible detections of two to five lines: GRB 060218, GRB 060202, GRB 050822, and GRB 050714B. Alternatively, a blackbody model with kT~0.1-0.5 keV can describe the soft emission in each afterglow. The most significant soft-component detections in the full data set of ~2000 spectra correspond to GRB 060218/SN 2006aj, with line significances ranging up to ~20 ?. A thermal plasma model fit to the data indicates that the flux is primarily due to L-shell transitions of Fe at roughly solar abundance. We associate (>4 ? significant) line triggers in the three other events with K-shell transitions in light metals. We favor a model where the possible line emission in these afterglows arises from the mildly relativistic cocoon of matter surrounding the GRB jet as it penetrates and exits the surface of the progenitor star. The emitting material in each burst is at a similar distance ~1012-1013 cm, a similar density ~1017 cm-3, and subject to a similar flux of ionizing radiation. The lines may correlate with the X-ray flaring. For the blackbody interpretation, the soft flux may arise from breakout of the GRB shock or plasma cocoon from the progenitor stellar wind, as recently suggested for GRB 060218 (Campana et al. 2006). Due to the low z of GRB 060218, bursts faint in gamma rays with fluxes dominated by this soft X-ray component could outnumber classical GRBs 100 to 1.

  17. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 108 2

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1 SIN 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  18. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, 08

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  19. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  20. SURFACE FILMS TO SUPPRESS FIELD EMISSION IN HIGH-POWER MICROWAVE COMPONENTS

    SciTech Connect

    Hirshfield, Jay l

    2014-02-07

    Results are reported on attempts to reduce the RF breakdown probability on copper accelerator structures by applying thin surface films that could suppress field emission of electrons. Techniques for application and testing of copper samples with films of metals with work functions higher than copper are described, principally for application of platinum films, since platinum has the second highest work function of any metal. Techniques for application of insulating films are also described, since these can suppress field emission and damage on account of dielectric shielding of fields at the copper surface, and on account of the greater hardness of insulating films, as compared with copper. In particular, application of zirconium oxide films on high-field portions of a 11.424 GHz SLAC cavity structure for breakdown tests are described.

  1. Resonator amplification of microwave emission from a relativistic beam-plasma system

    Microsoft Academic Search

    Gregory Benford; A. Ben-Amar Baranga

    1992-01-01

    Electromagnetic emission produced by a propagating electron beam in a cylindrical drift chamber can be amplified by axially reflecting screens. Radiation appears at the first and second plasma harmonics with linewidths of about 0.1 nu(p). Amplification scales with nu(p) squared and lags electron-beam voltage by several hundred nanoseconds, implying that electrostatic waves moving at the electron thermal speed must traverse

  2. Calculations of the spectral nature of the microwave emission from soils. [Arizona and Georgia

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Choudhury, B. J. (principal investigators)

    1980-01-01

    The brightness temperatures for a set of soil profiles observed at USDA facilities in Arizona and Georgia were calculated at the wavelengths of 2.8, 6, 11, 21, and 49 cm using a coherent radiative transfer model. The soil moisture sampling depth is found to be a function of wavelength and is in the range 0.06 to 0.1 of a wavelength. The thermal sampling depth also depends on wavelength and is approximately equal to one wavelength at dry soil condition and 0.1 - 0.5 wavelengths at wet soil conditions. Calculated values of emissivity show strong diurnal variations when the soils are wet, while there is little diurnal change when the soil is dry. The soil moistures within the four depth intervals of 0-2, 0-5, 0-9, and 0-15 cm were parameterized as function of the calculated emissivity and brightness temperature. Best-fit parameters and correlation coefficients are presented for five wavelengths. Interrelationships among the effective temperature, surface temperature, and emissivity are displayed.

  3. Emissivity measurements in thin metallized membrane reflectors used for microwave radiometer sensors

    NASA Technical Reports Server (NTRS)

    Schroeder, Lyle C.; Cravey, Robin L.; Scherner, Michael J.; Hearn, Chase P.; Blume, Hans-Juergen C.

    1995-01-01

    This paper is concerned with electromagnetic losses in metallized films used for inflatable reflectors. An inflatable membrane is made of tough elastic material such as Kapton, and it is not electromagnetically reflective by design. A film of conducting metal is added to the membrane to enhance its reflective properties. Since the impetus for use of inflatables for spacecraft is the light weight and compact packaging, it is important that the metal film be as thin as possible. However, if the material is not conductive or thick enough, the radiation due to the emissivity of the reflector could be a significant part of the radiation gathered by the radiometer. The emissivity would be of little consequence to a radar or solar collector; but for a radiometer whose signal is composed of thermal radiation, this contribution could be severe. Bulk properties of the metal film cannot be used to predict its loss. For this reason, a program of analysis and measurement was undertaken to determine the emissivities of a number of candidate metallized film reflectors. This paper describes the three types of measurements which were performed on the metallized thin films: (1) a network analyzer system with an L-band waveguide; (2) an S-band radiometer; and (3) a network analyzer system with a C-band antenna free-space transmission system.

  4. The microwave induced plasma with optical emission spectrometry (MIP-OES) in 23 elements determination in geological samples.

    PubMed

    Niedzielski, P; Kozak, L; Wachelka, M; Jakubowski, K; Wybieralska, J

    2015-01-01

    The article presents the optimisation, validation and application of the microwave induced plasma optical emission spectrometry (MIP-OES) dedicated for a routine determination of Ag, Al, B, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Ga, In, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sr, Tl, Zn, in the geological samples. The three procedures of sample preparation has been proposed: sample digestion with the use of hydrofluoric acid for determination of total concentration of elements, extraction by aqua regia for determination of the quasi-total element concentration and extraction by hydrochloric acid solution to determine contents of the elements in acid leachable fraction. The detection limits were on the level 0.001-0.121 mg L(-1) (from 0.010-0.10 to 1.2-12 mg kg(-1) depend on the samples preparation procedure); the precision: 0.20-1.37%; accuracy 85-115% (for recovery for certified standards materials analysis and parallel analysis by independent analytical techniques: X-ray fluorescence (XRF) and flame absorption spectrometry (FAAS)). The conformity of the results obtained by MIP-OES analytical procedures with the results obtained by XRF and FAAS analysis allows to propose the procedures for studies of elemental composition of the fraction of the geological samples. Additionally, the MIP-OES technique is much less expensive than ICP techniques and much less time-consuming than AAS techniques. PMID:25476349

  5. Characterization of low-pressure microwave and radio frequency discharges in oxygen applying optical emission spectroscopy and multipole resonance probe

    NASA Astrophysics Data System (ADS)

    Steves, Simon; Styrnoll, Tim; Mitschker, Felix; Bienholz, Stefan; Nikita, Bibinov; Awakowicz, Peter

    2013-11-01

    Optical emission spectroscopy (OES) and multipole resonance probe (MRP) are adopted to characterize low-pressure microwave (MW) and radio frequency (RF) discharges in oxygen. In this context, both discharges are usually applied for the deposition of permeation barrier SiOx films on plastic foils or the inner surface of plastic bottles. For technological reasons the MW excitation is modulated and a continuous wave (cw) RF bias is used. The RF voltage produces a stationary low-density plasma, whereas the high-density MW discharge is pulsed. For the optimization of deposition process and the quality of the deposited barrier films, plasma conditions are characterized using OES and MRP. To simplify the comparison of applied diagnostics, both MW and RF discharges are studied separately in cw mode. The OES and MRP diagnostic methods complement each other and provide reliable information about electron density and electron temperature. In the MW case, electron density amounts to ne = (1.25 ± 0.26) × 1017 m-3, and kTe to 1.93 ± 0.20 eV, in the RF case ne = (6.8 ± 1.8)×1015 m-3 and kTe = 2.6 ± 0.35 eV. The corresponding gas temperatures are 760±40 K and 440±20 K.

  6. The prediction of root zone soil moisture with a water balance - microwave emission model

    E-print Network

    Smith, Michael Robert

    1983-01-01

    ) where a (z) is the electric field attenuation constant. J is described by Planck's emission theory L17] as J Zhv 1 c exp(~) -I hv (11-7) h ? Planck's constant (6. 63xIA a4Joule k - Boltzmann's constant (1. 38x10- Joule/'K) c - speed of light (m/s... q"y+ gzz)( 23 But, since ax = ay = Bx = 0, (11-31) reduces to k = 8 + 8 - a + i28 a (11-32) Equating the real and imaginary components of (11-30) and (11-32) yields uupcpcR 8 + Bz oz 2 2 2 2 m uupcpci = 28 o 2 (11-33) (11-34) Assuming u...

  7. Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds

    NASA Astrophysics Data System (ADS)

    Schlegel, David J.; Finkbeiner, Douglas P.; Davis, Marc

    1998-06-01

    We present a full-sky 100 ?m map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. Before using the ISSA maps, we remove the remaining artifacts from the IRAS scan pattern. Using the DIRBE 100 and 240 ?m data, we have constructed a map of the dust temperature so that the 100 ?m map may be converted to a map proportional to dust column density. The dust temperature varies from 17 to 21 K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE quality calibration and IRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high-latitude regions, the dust map correlates well with maps of H I emission, but deviations are coherent in the sky and are especially conspicuous in regions of saturation of H I emission toward denser clouds and of formation of H2 in molecular clouds. In contrast, high-velocity H I clouds are deficient in dust emission, as expected. To generate the full-sky dust maps, we must first remove zodiacal light contamination, as well as a possible cosmic infrared background (CIB). This is done via a regression analysis of the 100 ?m DIRBE map against the Leiden-Dwingeloo map of H I emission, with corrections for the zodiacal light via a suitable expansion of the DIRBE 25 ?m flux. This procedure removes virtually all traces of the zodiacal foreground. For the 100 ?m map no significant CIB is detected. At longer wavelengths, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 32 +/- 13 nW m-2 sr-1 at 140 ?m and of 17 +/- 4 nW m-2 sr-1 at 240 ?m (95% confidence). This integrated flux ~2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law and use the colors of elliptical galaxies to measure the reddening per unit flux density of 100 ?m emission. We find consistent calibration using the B-R color distribution of a sample of the 106 brightest cluster ellipticals, as well as a sample of 384 ellipticals with B-V and Mg line strength measurements. For the latter sample, we use the correlation of intrinsic B-V versus Mg2 index to tighten the power of the test greatly. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates cosmic microwave background radiation experiments and for estimating soft X-ray absorption. We describe how to access our maps readily for general use.

  8. Five-Year Wilkinson Microwave Anisotropy Probe (WMAP1) Observations: Galactic Foreground Emission

    NASA Technical Reports Server (NTRS)

    Gold, B.; Bennett, C.L.; Larson, D.; Hill, R.S.; Odegard, N.; Weiland, J.L.; Hinshaw, G.; Kogut, A.; Wollack, E.; Page, L.; Dunkley, J.; Jarosik, N.; Spergel, N.; Halpern, M.; Komatsu, E.; Meyer, S.S.; Nolta, M.R.; Wright, E.L.

    2008-01-01

    We present a new estimate of foreground emission in the WMAP data, using a Markov chain Monte Carlo (MCMC) method. The new technique delivers maps of each foreground component for a variety of foreground models, error estimates of the uncertainty of each foreground component, and provides an overall goodness-of-fit measurement. The resulting foreground maps are in broad agreement with those from previous techniques used both within the collaboration and by other authors. We find that for WMAP data, a simple model with power-law synchrotron, free-free, and thermal dust components fits 90% of the sky with a reduced X(sup 2) (sub v) of 1.14. However, the model does not work well inside the Galactic plane. The addition of either synchrotron steepening or a modified spinning dust model improves the fit. This component may account for up to 14% of the total flux at Ka-band (33 GHz). We find no evidence for foreground contamination of the CMB temperature map in the 85% of the sky used for cosmological analysis.

  9. Molecular phonons and their absorption/emission spectra from the far IR to microwaves

    E-print Network

    Papoular, Renaud

    2015-01-01

    Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from $\\sim$20 to more than $10^{4}\\,\\mu$m, depending on molecular size. These spectra are discrete but large assemblies of molecules of the same family, differing only by minor structural details, will produce continua. As such assemblies are expected to exist in regions where dust accumulates, they are bound to contribute to the observed continua underlying the Unidentified Infrared Bands and the 21-mum band of planetary nebulae as well as to the diffuse galactic emission surveyed by the Planck astronomical satellite and other means. The purpose of this work is to determine, for carbon-rich molecules, the intensity of such continua and their extent into the millimetric range, and to evaluate their detectability in this range. The rules governing the spectral distributions of phonons are derived and shown to differ from those which obtain in the solid state. Their application allow th...

  10. Low gas flow inductively coupled plasma optical emission spectrometry for the analysis of food samples after microwave digestion.

    PubMed

    Nowak, Sascha; Gesell, Monika; Holtkamp, Michael; Scheffer, Andy; Sperling, Michael; Karst, Uwe; Buscher, Wolfgang

    2014-11-01

    In this work, the recently introduced low flow inductively coupled plasma optical emission spectrometry (ICP-OES) with a total argon consumption below 0.7 L/min is applied for the first time to the field of food analysis. One goal is the investigation of the performance of this low flow plasma compared to a conventional ICP-OES system when non-aqueous samples with a certain matrix are introduced into the system. For this purpose, arsenic is determined in three different kinds of fish samples. In addition several nutrients (K, Na, Mg, Ca) and trace metals (Co, Cu, Mn, Cd, Pb, Zn, Fe, and Ni) are determined in honey samples (acacia) after microwave digestion. The precision of the measurements is characterized by relative standard deviations (RSD) and compared to the corresponding precision values achieved using the conventional Fassel-type torch of the ICP. To prove the accuracy of the low flow ICP-OES method, the obtained data from honey samples are validated by a conventional ICP-OES. For the measurements concerning arsenic in fish, the low flow ICP-OES values are validated by conventional Fassel-type ICP-OES. Furthermore, a certified reference material was investigated with the low gas flow setup. Limits of detection (LOD), according to the 3? criterion, were determined to be in the low microgram per liter range for all analytes. Recovery rates in the range of 96-106% were observed for the determined trace metal elements. It was proven that the low gas flow ICP-OES leads to results that are comparable with those obtained with the Fassel-type torch for the analysis of food samples. PMID:25127635

  11. Application of microwave plasma atomic emission spectrometry (MP-AES) for environmental monitoring of industrially contaminated sites in Hyderabad city.

    PubMed

    Kamala C T; Balaram V; Dharmendra V; Satyanarayanan M; Subramanyam K S V; Krishnaiah A

    2014-11-01

    Recently introduced microwave plasma-atomic emission spectroscopy (MP-AES) represents yet another and very important addition to the existing array of modern instrumental analytical techniques. In this study, an attempt is made to summarize the performance characteristics of MP-AES and its potential as an analytical tool for environmental studies with some practical examples from Patancheru and Uppal industrial sectors of Hyderabad city. A range of soil, sediment, water reference materials, particulate matter, and real-life samples were chosen to evaluate the performance of this new analytical technique. Analytical wavelengths were selected considering the interference effects of other concomitant elements present in different sample solutions. The detection limits for several elements were found to be in the range from 0.05 to 5 ng/g. The trace metals analyzed in both the sectors followed the topography with more pollution in the low-lying sites. The metal contents were found to be more in ground waters than surface waters. Since a decade, the pollutants are transfered from Patancheru industrial area to Musi River. After polluting Nakkavagu and turning huge tracts of agricultural lands barren besides making people residing along the rivulet impotent and sick, industrialists of Patancheru are shifting the effluents to downstream of Musi River through an 18-km pipeline from Patancheru. Since the effluent undergoes primary treatment at Common Effluent Treatment Plant (CETP) at Patanchru and travels through pipeline and mixes with sewage, the organic effluents will be diluted. But the inorganic pollutants such as heavy and toxic metals tend to accumulate in the environmental segments near and downstreams of Musi River. The data generated by MP-AES of toxic metals like Zn, Cu, and Cr in the ground and surface waters can only be attributed to pollution from Patancheru since no other sources are available to Musi River. PMID:25086712

  12. Impact of Hillslope-Scale Organization of Topography, Soil Moisture, Soil Temperature, and Vegetation on Modeling Surface Microwave Radiation Emission

    E-print Network

    Flores, Alejandro N.

    Microwave radiometry will emerge as an important tool for global remote sensing of near-surface soil moisture in the coming decade. In this modeling study, we find that hillslope-scale topography (tens of meters) influences ...

  13. Desolvation of acid solutions in inductively coupled plasma atomic emission spectrometry by infrared radiation. Comparison with a system based on microwave radiation

    NASA Astrophysics Data System (ADS)

    Gras, Luis; Mora, Juan; Todolí, José L.; Canals, Antonio; Hernandis, Vicente

    1999-09-01

    The behaviour of an infrared desolvation system with acid solutions in inductively coupled plasma atomic emission spectrometry (ICP-AES) is evaluated, and the influence of the liquid uptake rate and of the nature and concentration of the acid on the solvent and analyte transport rates and on the analytical figures of merit is studied. The results are compared with those obtained with a desolvation system based on the absorption of microwave radiation. The infrared desolvation system performs best at low sample uptake rates (0.4 ml min -1) and its behaviour strongly depends on the nature and concentration of the solution used. With nitric and hydrochloric solutions, there is almost no effect of the acid concentration on the emission intensity, while for sulfuric and perchloric acids the signal decreases as the acid concentration is increased. These effects seem to be related with the different capability of the acid aerosols to be heated in an IR field. The microwave desolvation system seems to be more prone to matrix (acid) effects, specially when using sulfuric and perchloric acids, resulting in emission intensities which are usually lower than those obtained with the infrared desolvation system, though their limits of detection are quite similar.

  14. X-radiation /E greater than 10 keV/, H-alpha and microwave emission during the impulsive phase of solar flares.

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.

    1972-01-01

    A study has been made of the variation in hard (E greater than 10 keV) X-radiation, H-alpha and microwave emission during the impulsive phase of solar flares. Analysis shows that the rise-time in the 20-30-keV X-ray spike depends on the electron hardness. The impulsive phase is also marked by an abrupt, very intense increase in H-alpha emission in one or more knots of the flare. Properties of these H-alpha kernels include: (1) a luminosity several times greater than the surrounding flare, (2) an intensity rise starting about 20-30 sec before, peaking about 20-25 sec after, and lasting about twice as long as the hard spike, (3) a location lower in the chromosphere than the remaining flare, (4) essentially no expansion prior to the hard spike, and (5) a position within 6000 km of the boundary separating polarities, usually forming on both sides of the neutral line near both feet of the same tube of force. Correspondingly, impulsive microwave events are characterized by: (1) great similarity in burst structure with 20-32 keV X-rays but only above 5000 MHz, (2) typical low frequency burst cutoff between 1400-3800 MHz, and (3) maximum emission above 7500 MHz.

  15. The emission and scattering of L-band microwave radiation from rough ocean surfaces and wind speed measurements from the Aquarius sensor

    NASA Astrophysics Data System (ADS)

    Meissner, Thomas; Wentz, Frank J.; Ricciardulli, Lucrezia

    2014-09-01

    In order to achieve the required accuracy in sea surface salinity (SSS) measurements from L-band radiometers such as the Aquarius/SAC-D or SMOS (Soil Moisture and Ocean Salinity) mission, it is crucial to accurately correct the radiation that is emitted from the ocean surface for roughness effects. We derive a geophysical model function (GMF) for the emission and backscatter of L-band microwave radiation from rough ocean surfaces. The analysis is based on radiometer brightness temperature and scatterometer backscatter observations both taken on board Aquarius. The data are temporally and spatially collocated with wind speeds from WindSat and F17 SSMIS (Special Sensor Microwave Imager Sounder) and wind directions from NCEP (National Center for Environmental Prediction) GDAS (Global Data Assimilation System). This GMF is the basis for retrieval of ocean surface wind speed combining L-band H-pol radiometer and HH-pol scatterometer observations. The accuracy of theses combined passive/active L-band wind speeds matches those of many other satellite microwave sensors. The L-band GMF together with the combined passive/active L-band wind speeds is utilized in the Aquarius SSS retrieval algorithm for the surface roughness correction. We demonstrate that using these L-band wind speeds instead of NCEP wind speeds leads to a significant improvement in the SSS accuracy. Further improvements in the roughness correction algorithm can be obtained by adding VV-pol scatterometer measurements and wave height (WH) data into the GMF.

  16. Vacuum Ultraviolet Emission Spectrum Measurement of a Microwave-discharge Hydrogen-flow Lamp in Several Configurations: Application to Photodesorption of CO Ice

    NASA Astrophysics Data System (ADS)

    Chen, Y.-J.; Chuang, K.-J.; Muñoz Caro, G. M.; Nuevo, M.; Chu, C.-C.; Yih, T.-S.; Ip, W.-H.; Wu, C.-Y. R.

    2014-01-01

    We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogen-flow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly-? (121.6 nm) and H2 molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly-? to molecular emission bands, strongly depend on the pressure of H2 inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H2 versus H2 seeded in He), and the optical properties of the window used (MgF2 versus CaF2). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly-? and H2 molecular emission ranges.

  17. Microwave backscatter and emission observed from Shuttle Imaging Radar B and an airborne 1.4 GHz radiometer

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Schiue, J. C.; Schmugge, T. J.; Engman, E. T.; Mo, T.; Lawrence, R. W.

    1985-01-01

    A soil moisture experiment conducted with the Shuttle Imaging Radar B (SIR-B) is reported. SIR-B operated at 1.28 GHz provided the active microwave measurements, while a 4-beam pushbroom 1.4 GHz radiometer gave the complementary passive microwave measurements. The aircraft measurements were made at an altitude of 330 m, resulting in a ground resolution cell of about 100 m diameter. SIR-B ground resolution from 225 km was about 35 m. More than 150 agricultural fields in the San Joaquin Valley of California were examined in the experiment. The effect of surface roughness height on radar backscatter and radiometric measurements was studied.

  18. Simulation of the microwave emission of multi-layered snowpacks using the Dense Media Radiative transfer theory: the DMRT-ML model

    NASA Astrophysics Data System (ADS)

    Picard, G.; Brucker, L.; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Harlow, C.

    2013-07-01

    DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by space-based microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large ice-sheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

  19. Simulation of the Microwave Emission of Multi-layered Snowpacks Using the Dense Media Radiative Transfer Theory: the DMRT-ML Model

    NASA Technical Reports Server (NTRS)

    Picard, G.; Brucker, Ludovic; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Harlow, C.

    2013-01-01

    DMRT-ML is a physically based numerical model designed to compute the thermal microwave emission of a given snowpack. Its main application is the simulation of brightness temperatures at frequencies in the range 1-200 GHz similar to those acquired routinely by spacebased microwave radiometers. The model is based on the Dense Media Radiative Transfer (DMRT) theory for the computation of the snow scattering and extinction coefficients and on the Discrete Ordinate Method (DISORT) to numerically solve the radiative transfer equation. The snowpack is modeled as a stack of multiple horizontal snow layers and an optional underlying interface representing the soil or the bottom ice. The model handles both dry and wet snow conditions. Such a general design allows the model to account for a wide range of snow conditions. Hitherto, the model has been used to simulate the thermal emission of the deep firn on ice sheets, shallow snowpacks overlying soil in Arctic and Alpine regions, and overlying ice on the large icesheet margins and glaciers. DMRT-ML has thus been validated in three very different conditions: Antarctica, Barnes Ice Cap (Canada) and Canadian tundra. It has been recently used in conjunction with inverse methods to retrieve snow grain size from remote sensing data. The model is written in Fortran90 and available to the snow remote sensing community as an open-source software. A convenient user interface is provided in Python.

  20. Anomalous conductivity in Hall thrusters: Effects of the non-linear coupling of the electron-cyclotron drift instability with secondary electron emission of the walls

    NASA Astrophysics Data System (ADS)

    Héron, A.; Adam, J. C.

    2013-08-01

    With the help of an implicit particle-in-cell code, we have shown in a previous paper that the electron-cyclotron drift instability was able to induce anomalous conductivity as well as anomalous heating. As such it can be a major actor among the mechanisms involved in the operation of Hall thrusters. However, experimental results show that the nature of wall material has a significant effect on the behavior of the thruster. The purpose of this paper is to study the plasma-wall interaction in the case where the plasma is heated self-consistently by electrostatic fluctuations induced by the electron-cyclotron drift instability.

  1. Anomalous conductivity in Hall thrusters: Effects of the non-linear coupling of the electron-cyclotron drift instability with secondary electron emission of the walls

    SciTech Connect

    Héron, A.; Adam, J. C. [Centre de physique théorique, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex (France)] [Centre de physique théorique, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-08-15

    With the help of an implicit particle-in-cell code, we have shown in a previous paper that the electron-cyclotron drift instability was able to induce anomalous conductivity as well as anomalous heating. As such it can be a major actor among the mechanisms involved in the operation of Hall thrusters. However, experimental results show that the nature of wall material has a significant effect on the behavior of the thruster. The purpose of this paper is to study the plasma-wall interaction in the case where the plasma is heated self-consistently by electrostatic fluctuations induced by the electron-cyclotron drift instability.

  2. Measurements of plasma temperatures in H\\/sub 2\\/\\/carbon\\/AR microwave plasma by UV emission spectroscopy

    Microsoft Academic Search

    Yongho Kim; S. Abbate; G. Anderson; L. Rosocha; H. Ziock

    2006-01-01

    Summary form only given. We have developed a microwave plasma at atmospheric pressure in the mixtures of hydrogen, carbon, and argon in order to study the hydrogasification reaction of coal. A coal gasification is a newly highlighted research field because coal is abundant energy source for methane or hydrogen. However, the coal gasification process has encountered technical barriers because no

  3. The Contribution of Galactic Free-Free Emission to Anisotropies in the Cosmic Microwave Background Radiation Measured by MSAM

    Microsoft Academic Search

    J. H. Simonetti; G. A. Topasna; B. Dennison

    1996-01-01

    The Medium Scale Anisotropy Measurement (MSAM) experiment has detected anisotropies in the cosmic microwave background radiation with an rms between about 30 mu K and 90 mu K. MSAM uses double-difference and single-difference demodulation signals from a chopped, 30(') beam at a number of frequencies between 170 and 680 GHz. We observed the region covered by MSAM using the Virginia

  4. Optimization and evaluation of different chemical and electrochemical hydride generation systems for the determination of arsenic by microwave plasma torch optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    Özmen, Burcu; Matysik, Frank-Michael; Bings, Nicolas H.; Broekaert, José A. C.

    2004-07-01

    The determination of trace concentrations of As and its species in water and sediment samples by the use of microwave plasma torch optical emission spectrometry (MPT-OES) and chemical (CHG) as well as different electrochemical hydride generation (EcHG) systems was studied, when using Ar and He as working gases for the microwave plasmas. Under optimized conditions and with He as working gas the detection limits (3 ?) for As (228.82 nm) were found to be 21 and 13 ?g/l for chemical and electrochemical hydride generation, respectively. When Ar is used as working gas, the detection limits are higher, i.e., 60 and 48 ?g/l for chemical and electrochemical hydride generation, respectively. Several miniaturized electrochemical hydride generation cells, among which some use glassy carbon foam and carbon fiber for the cathode, were used and the detection limits with these systems were found to be by a factor of 3-5 higher than in the conventional electrochemical hydride generation cell. The effects of Ca, Fe, Bi, Se, etc., on the determination of As with chemical and miniaturized electrochemical hydride generation systems were studied, and it was found that the interferences in electrochemical hydride generation were lower than in chemical hydride generation. The efficiency of the generation of AsH 3 in chemical hydride generation and all electrochemical hydride generation systems, as determined by a coulometric titration of the remaining As(III) in the waste solutions of the gas-liquid separator, was found to be below 18% to 90%, depending on the cells. A modified graphite furnace (GF) unit was coupled to the hydride generation system for hot-trapping of the hydride forming elements. When trapping the AsH 3 produced in a miniaturized electrochemical hydride generation system on Pd in a graphite furnace and sweeping the As into the He microwave plasma torch, the detection limit for As could be improved to 1.7 ?g/l (improvement by a factor of 14). The procedure without trapping could be used for the determination of As in a standard reference water (SRM 1643d) containing 56.02±0.73 mg/l of total As within an experimental error of 8%. With the miniaturized electrochemical hydride generation and microwave plasma torch emission spectrometry in the case of trapping the total As could be determined in Saxony river sediment samples and in Hungarian spring water samples at the 10-30 and 50-360 ?g/l levels, respectively.

  5. High power microwave generator

    DOEpatents

    Ekdahl, Carl A. (Albuquerque, NM)

    1986-01-01

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  6. High power microwave generator

    DOEpatents

    Ekdahl, C.A.

    1983-12-29

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  7. Chlorine and sulfur determination in extra-heavy crude oil by inductively coupled plasma optical emission spectrometry after microwave-induced combustion

    NASA Astrophysics Data System (ADS)

    Pereira, Juliana S. F.; Mello, Paola A.; Moraes, Diogo P.; Duarte, Fábio A.; Dressler, Valderi L.; Knapp, Guenter; Flores, Érico M. M.

    2009-06-01

    In this study, microwave-induced combustion (MIC) of extra-heavy crude oil is proposed for further chlorine and sulfur determination by inductively coupled plasma optical emission spectrometry (ICP OES). Combustion was carried out under oxygen pressure (20 bar) in quartz vessels using ammonium nitrate (50 µl of 6 mol l - 1 solution) as ignition aid. Samples were wrapped with polyethylene film and placed on a quartz holder positioned inside the quartz vessels. The need for an additional reflux step after combustion and the type and concentration of absorbing solution (water, 0.02 to 0.9 mmol l - 1 H 2O 2, 10 to 100 mmol l - 1 (NH 4) 2CO 3 or 0.1 to 14 mol l - 1 HNO 3) were studied. The influence of sample mass, O 2 pressure and maximum pressure attained during the combustion process were investigated. Recoveries from 92 to 102% were obtained for Cl and S for all absorbing solutions. For comparison, Cl and S determination was also performed by ion chromatography (IC) using 25 mmol l - 1 (NH 4) 2CO 3 as absorbing solution. Using MIC with a reflux step the agreement was better than 95% for certified reference materials of similar composition (crude oil, petroleum coke, coal and residual fuel oil). Microwave-assisted digestion and water extraction in high pressure closed vessels were also evaluated. Using these procedures the maximum recoveries were 30 and 98% for Cl and S, respectively, using microwave-assisted digestion and 70% for Cl and less than 1% for S by water extraction procedure. Limits of detection by ICP OES were 12 and 5 µg g - 1 for Cl and S, respectively, and the corresponding values by IC were 1.2 and 8 µg g - 1 . Using MIC it was possible to digest simultaneously up to eight samples resulting in a solution suitable for the determination of both analytes with a single combustion step.

  8. Electrodynamics of Magnetars: Implications for the Persistent X-Ray Emission and Spin-down of the Soft Gamma Repeaters and Anomalous X-Ray Pulsars

    Microsoft Academic Search

    C. Thompson; M. Lyutikov; S. R. Kulkarni

    2002-01-01

    We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra and pulse profiles. In the magnetar model for the soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs), these currents are maintained by magnetic stresses acting deep

  9. The theory of an auto-resonant field emission cathode relativistic electron accelerator for high efficiency microwave to direct current power conversion

    NASA Technical Reports Server (NTRS)

    Manning, Robert M.

    1990-01-01

    A novel method of microwave power conversion to direct current is discussed that relies on a modification of well known resonant linear relativistic electron accelerator techniques. An analysis is presented that shows how, by establishing a 'slow' electromagnetic field in a waveguide, electrons liberated from an array of field emission cathodes, are resonantly accelerated to several times their rest energy, thus establishing an electric current over a large potential difference. Such an approach is not limited to the relatively low frequencies that characterize the operation of rectennas, and can, with appropriate waveguide and slow wave structure design, be employed in the 300 to 600 GHz range where much smaller transmitting and receiving antennas are needed.

  10. Analysis of regolith electromagnetic scattering as constrained by high resolution Earth-based measurements of the lunar microwave emission

    NASA Technical Reports Server (NTRS)

    Keihm, S. J.

    1983-01-01

    When high resolution measurements of the phase variation of the lunar disk center brightness temperature revealed that in situ regolith electrical losses were larger than those measured on returned samples by a factor of 1.5 to 2.0 at centimeter wavelengths, the need for a refinement of the regolith model to include realistic treatment of scattering effects was identified. Two distinct scattering regimes are considered: vertial variations in dielectric constant and volume scattering due to subsurface rock fragments. Models of lunar regolith energy transport processes are now at the state for which a maximum scientific return could be realized from a lunar orbiter microwave mapping experiment. A detailed analysis, including the effects of scattering produced a set of nominal brightness temperature spectra for lunar equatorial regions, which can be used for mapping as a calibration reference for mapping variations in mineralogy and heat flow.

  11. Thermal microwave emissions from vegetated fields: A comparison between theory and experiment. [Agricultural Research Center, Beltsville, MD.

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Shiue, J.; Chuang, S. L.; Dombrowski, M.

    1980-01-01

    The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4 GHz and 5 GHz microwave radiometers during August - October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature T(B) than that expected from a bare soil. The amount of this T(B) excess increases in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations generally match well with the experimental data, however, a detailed analysis also strongly suggests the need of incorporating soil surface roughness effect into the radiative transfer theory in order to better interpret the experimental data.

  12. Translational anisotropy in the cosmic microwave background radiation and far-infrared emission by galactic dust clouds

    NASA Technical Reports Server (NTRS)

    Forman, M. A.

    1977-01-01

    The predicted emission spectrum of galactic dust at about 10 K is compared with the spectrum of 2.8-K universal blackbody radiation and with the spectrum of the anisotropy expected in the 2.8-K radiation due to motion of earth with respect to the coordinate system in which the radiation was last scattered. The extremely anisotropic galactic-dust emission spectrum may contribute a significant background to anisotropy measurements which scan through the galactic plane. The contamination would appear in an 8-mm scan around the celestial equator, for example, as a spurious 200 km/s velocity toward declination 0 deg, right ascension 19 hr, if predictions are correct. The predicted spectrum of dust emission in the galactic plane at longitudes not exceeding about 30 deg falls below the total 2.8-K cosmic background intensity at wavelengths of at least 1 mm.

  13. Resonances in the Microwave Emission from a Bounded Magnetoplasma with omegap\\/omega>1 and omegac\\/omega>1

    Microsoft Academic Search

    S. J. Tetenbaum

    1972-01-01

    The X-band far-field emission from RF-excited helium, neon and argon rectangular and cylindrical magnetoplasmas has been experimentally investigated in the parameter range in which both omegap\\/omega and omegac\\/omega exceed one. A series of sharp resonances was found which generally broaden and increase in amplitude and separation as the magnetic field increases. Some peaks have Q's greater than 300. The peaks

  14. Growth, microstructure, and field-emission properties of synthesized diamond film on adamantane-coated silicon substrate by microwave plasma chemical vapor deposition

    SciTech Connect

    Tiwari, Rajanish N.; Chang Li [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan 300 (China)

    2010-05-15

    Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {l_brace}100{r_brace} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was {approx}530 deg. C during diamond deposition. The deposited films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/{mu}m) and high current-density (1.6 mA/cm{sup 2}) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

  15. Microwave-promoted pure host phase for red emission CaS:Eu2+ phosphor from single CaSO4 precursor and the photoluminescence property

    NASA Astrophysics Data System (ADS)

    Ma, Jian; Lu, Qi-Fei; Wang, Yan-Ze; Lu, Zhi-Juan; Sun, Liang; Dong, Xiao-Fei; Wang, Da-Jian

    2014-08-01

    We report a novel approach to obtaining a classical blue-green excitable CaS:Eu2+ phosphor with desired red emission by microwave (MW) firing procedure in the absence of adding elemental sulphur. The disturbing effect of MW electromagnetic field on decomposition of CaSO4 into CaS activated by europium is distinctly observed to give pure host phase without adding any elemental sulphur and carbon. The host phase evolution is observed to be highly dependent on the variation of applied MW power from X-ray diffraction (XRD) patterns and the corresponding photoluminescence (PL), and a maximum PL intensity at 1100 W of MW power is acquired for the obtained purer host phase. The non-thermal and non-equilibrium effects by MW are revealed to correlate with the interaction between polar structure of the host and applied electromagnetic field. The results demonstrate an optional procedure to prepare this red-emitting phosphor in an effective, environment-friendly and scalable approach for phosphor production in the application of bio-illumination for plant cultivation and artificial photosynthesis.

  16. Determination of carbon in aqueous solutions by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry with gas-phase sample introduction technique.

    PubMed

    Matsumoto, Akihiro; Nakahara, Taketoshi

    2003-03-01

    A trace amount of carbon was determined by atmospheric-pressure helium microwave induced plasma atomic emission spectrometry (He-MIP-AES) with gas-phase sample introduction technique. This method was applied for the generation of a continuous flow of carbon dioxide by the acidification of carbonate ion and hydrogen carbonate ion for the determination of carbon. The generated carbon dioxide was separated from the solution by a simple gas-liquid separator, dried with a desiccant and swept into the MIP with helium carrier gas for analysis. Of the acids and drying agents investigated, hydrochloric acid for acidification and anhydrous calcium chloride as a desiccant were found to be the most appropriate for the generation of carbon dioxide. Under the optimized experimental conditions, the best attainable detection limits at C (I) 193.09 and C (I) 247.86 nm lines were 7.89 and 8.10 microg/l with linear dynamic ranges of 100 to 10,000 and 100 to 20,000 microg/l for carbon, respectively. The presence of many diverse elements and ions was found to cause a more or less depressing interference by the proposed technique. However, no interference was observed from the following elements and ions: Ca, K, Rb, Br-, Cl-, F- and I-. Finally, the present method has been applied to the determination of carbon in several water samples. PMID:12675347

  17. Hard X-ray emission cutoff in the anomalous X-ray pulsar 4U 0142+61 detected by INTEGRAL

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Tong, Hao; Guo, Yan-Jun

    2014-06-01

    The anomalous X-ray pulsar 4U 0142+61 has been studied with observations from INTEGRAL. The hard X-ray spectrum in the range 18-500 keV for 4U 0142+61 was derived using nearly nine years of INTEGRAL/IBIS data. We obtained the average hard X-ray spectrum of 4U 0142+61 with all available data. The spectrum of 4U 0142+61 can be fitted with a power law that includes an exponential high energy cutoff. This average spectrum is well fitted by a power law with ? ~ 0.51 ± 0.11 plus a cutoff energy at 128.6 ± 17.2 keV. The hard X-ray flux of the source from 20-150 keV showed no significant variations (within 20%) from 2003-2011. The spectral profiles have some variability over the nine years such that the photon index varies from 0.3-1.5 and the cutoff energies from 110-250 keV. The detection of the high energy cutoff around 130 keV shows some constraints on the radiation mechanisms of magnetars and possibly probes the differences between magnetar and accretion models for this special class of neutron stars. Future HXMT observations could provide stronger constraints on the hard X-ray spectral properties of this source and other magnetar candidates.

  18. Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from Comet 103P/Hartley 2 during the EPOXI encounter

    NASA Astrophysics Data System (ADS)

    Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Dennerl, K.; Bodewits, D.; Combi, M. R.; Lepri, S. T.; Zurbuchen, T. H.; Li, J. Y.; Dello-Russo, N.; Belton, M. J. S.; Knight, M. M.

    2013-02-01

    We present results from the Chandra X-ray Observatory's characterization of the X-ray emission from Comet 103P/Hartley 2, in support of NASA's Deep Impact Extended close flyby of the comet on 04 November 2010. The comet was observed 4 times for a total on target time of ˜60 ks between the 17th of October and 16th of November 2010, with two of the visits occurring during the EPOXI close approach on 04 November and 05 November 2010. X-ray emission from 103P was qualitatively similar to that observed for collisionally thin Comets 2P/Encke (Lisse, C.M. et al. [2005]. Astrophys. J. 635, 1329-1347) and 9P/Tempel 1 (Lisse, C.M. et al. [2007]. Icarus 190, 391-405). Emission morphology offset sunward but asymmetrical from the nucleus and emission lines produced by charge exchange between highly stripped C, N, and O solar wind minor ions and coma neutral gas species were found. The comet was very under-luminous in the X-ray at all times, representing the 3rd faintest comet ever detected (LX = 1.1 ± 0.3 × 1014 erg s-1). The coma was collisionally thin to the solar wind at all times, allowing solar wind ions to flow into the inner coma and interact with the densest neutral coma gas. Localization of the X-ray emission in the regions of the major rotating gas jets was observed, consistent with the major source of cometary neutral gas species being icy coma dust particles. Variable spectral features due to changing solar wind flux densities and charge states were also seen. Modeling of the Chandra observations from the first three visits using observed gas production rates and ACE solar wind ion fluxes with a charge exchange mechanism for the emission is consistent with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma. The X-ray emission during the 4th visit on 16 November 2010 is similar to the unusual behavior seen for Comet 17P/Holmes in 2007 (Christian, D.J. et al. [2010]. Astrophys. J. Suppl. 187, 447-459) as the solar wind became dominated by a less ionized and faster plasma, more typical of outflow from polar coronal hole regions. We postulate that the overall faintness of the comet seen during all visits is due to the unusually well mixed dust and gas content of this hyperactive comet's coma producing Auger electrons rather than X-rays via charge exchange with the solar wind. An alternative possible explanation for the faintness of the comet's X-ray emission, and its unusual high CV and unusually low CVI emission, is that the impinging solar wind was drastically slowed in the inner coma, below 150 km s-1, before charge exchanging with cometary neutrals.

  19. Microwave off-gas treatment apparatus and process

    DOEpatents

    Schulz, Rebecca L. (Aiken, SC); Clark, David E. (Gainesville, FL); Wicks, George G. (North Aiken, SC)

    2003-01-01

    The invention discloses a microwave off-gas system in which microwave energy is used to treat gaseous waste. A treatment chamber is used to remediate off-gases from an emission source by passing the off-gases through a susceptor matrix, the matrix being exposed to microwave radiation. The microwave radiation and elevated temperatures within the combustion chamber provide for significant reductions in the qualitative and quantitative emissions of the gas waste stream.

  20. Recent Advancements in Microwave Imaging Plasma Diagnostics

    SciTech Connect

    H. Park; C.C. Chang; B.H. Deng; C.W. Domier; A.J.H. Donni; K. Kawahata; C. Liang; X.P. Liang; H.J. Lu; N.C. Luhmann, Jr.; A. Mase; H. Matsuura; E. Mazzucato; A. Miura; K. Mizuno; T. Munsat; K. and Y. Nagayama; M.J. van de Pol; J. Wang; Z.G. Xia; W-K. Zhang

    2002-03-26

    Significant advances in microwave and millimeter wave technology over the past decade have enabled the development of a new generation of imaging diagnostics for current and envisioned magnetic fusion devices. Prominent among these are revolutionary microwave electron cyclotron emission imaging (ECEI), microwave phase imaging interferometers, imaging microwave scattering and microwave imaging reflectometer (MIR) systems for imaging electron temperature and electron density fluctuations (both turbulent and coherent) and profiles (including transport barriers) on toroidal devices such as tokamaks, spherical tori, and stellarators. The diagnostic technology is reviewed, and typical diagnostic systems are analyzed. Representative experimental results obtained with these novel diagnostic systems are also presented.

  1. Microwave detector

    DOEpatents

    Meldner, Heiner W. (Moss Beach, CA); Cusson, Ronald Y. (Chapel Hill, NC); Johnson, Ray M. (San Ramon, CA)

    1986-01-01

    A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  2. Microwave detector

    DOEpatents

    Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

    1985-02-08

    A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  3. A Possible Explanation of Anomalous Earth Flybys

    E-print Network

    Walter Petry

    2008-06-02

    Doppler shift observations of several spacecrafts during near Earth flybys show an unexplained frequency shift. This shift is interpreted as an unexpected velocity change called Earth flyby anomaly. A theory of non-privileged reference frames is used to study the Doppler shift in such frames which are experimentally justified by the measured dipole anisotropy of the cosmic microwave background (CMB) in the solar system. The system in which the CMB is isotropic defines the privileged reference frame. The calculated frequency shift in non-privileged reference frames may give an explanation of the anomalous Earth flybys.

  4. Anomalous diffusion of pions at RHIC

    E-print Network

    M. Csanad; T. Csorgo; M. Nagy

    2007-04-12

    After pointing out the difference between normal and anomalous diffusion, we consider a hadron resonance cascade (HRC) model simulation for particle emission at RHIC and point out, that rescattering in an expanding hadron resonance gas leads to a heavy tail in the source distribution. The results are compared to recent PHENIX measurements of the tail of the particle emitting source in Au+Au collisions at RHIC. In this context, we show, how can one distinguish experimentally the anomalous diffusion of hadrons from a second order QCD phase transition.

  5. Analysis of hard X- and gamma-rays and microwave emissions during the flare of July 18, 2002

    NASA Astrophysics Data System (ADS)

    Charikov, Yu. E.; Aptekar, R. L.; Golenetsky, S. V.; Kudryavtsev, I. V.; Kuznetsov, S. A.; Melnikov, V. F.; Pal'shin, V. D.; Svinkin, D. S.; Sokolova, Z. Ya.; Ulanov, M. V.; Frederiks, D. D.; Tsvetkova, A. E.; Shabalin, A. N.

    2014-12-01

    The Nobeyama Radioheliograph observation results and data from the KONUS-Wind spectrometer mounted at the Wind and RHESSI satellites on several solar flares are jointly analyzed. The analysis results for data on the flare of July 18, 2002 are described. The hard X-rays were measured in the 18 keV-15 MeV range (KONUS-Wind), and spectroheliograph measurements were carried out in the radio range at frequencies of 17 and 34 GHz. Spatial distributions of the radio brightness were calculated for the flare of July 18, 2002; they show the presence of two sources at the footpoints and one source at the top of the supposed flaring loop. The energy spectra of hard X-rays, energy flux, and the total number of accelerated electrons were found from the KONUS spectrometer data. The number of accelerated X-ray emitted electrons was estimated as N ? 1036, and the maximum X-ray energy flux was estimated as ˜5 × 10-6 erg cm-2 s-1. The spectrum index varies in time from -4.6 to -3.6, i.e., the soft-hard-harder trend is implemented. The spectral index of the radio waves is ? ? -0.3 at the flare start, attains the value ? ? -0.5 at the flux maximum, and even change the sign further. The accelerated electron transport model in the flare loop plasma is suggested for interpretation of relationships between parameters of the radio emission and hard X-rays.

  6. Microwave Ovens

    MedlinePLUS

    ... be used in cooking: they are reflected by metal; they pass through glass, paper, plastic, and similar materials; and they are absorbed by foods. A device called a magnetron inside the oven produces microwaves. The microwaves reflect off the metal interior of the oven and cause the water ...

  7. Microwave Playdough

    NSDL National Science Digital Library

    2012-06-26

    This is a recipe for playdough made by mixing household ingredients and cooking it in a microwave. This recipe includes suggestions for artistic embellishments to enhance the sensory experience, like adding glitter or color to the dough. The dough can be used to create simple sculptures, or cast molds of objects. Important: DO NOT add glitter to the mixture before microwaving.

  8. Measurement of Anomalously Strong Emission from the 1s-9p Transition in the Spectrum of H-like Phosphorus Following Charge Exchange with Molecular Hydrogen

    NASA Technical Reports Server (NTRS)

    Leutenegger, M. A.; Beiersdorfer, P.; Brown, G. V.; Kelley, R. L.; Porter, F. S.

    2010-01-01

    We have measured K-shell x-ray spectra of highly ionized argon and phosphorus following charge exchange with molecular hydrogen at low collision energy in an electron beam ion trap using an x-ray calorimeter array with approx.6 eV resolution. We find that the emission at the high-end of the Lyman series is greater by a factor of two for phosphorus than for argon, even though the measurement was performed concurrently and the atomic numbers are similar. This does not agree with current theoretical models and deviates from the trend observed in previous measurements.

  9. BURST AND PERSISTENT EMISSION PROPERTIES DURING THE RECENT ACTIVE EPISODE OF THE ANOMALOUS X-RAY PULSAR 1E 1841-045

    SciTech Connect

    Lin Lin [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, Istanbul 34956 (Turkey); Van der Horst, Alexander J. [Universities Space Research Association, NSSTC, Huntsville, AL 35805 (United States); Watts, Anna L.; Wijers, Ralph A. M. J.; Van der Klis, Michiel [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, 1090 GE Amsterdam (Netherlands); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, Houston, TX 77251 (United States); Woods, Peter M. [Corvid Technologies, Huntsville, AL 35806 (United States); Barthelmy, Scott; Gehrels, Neil; Mcenery, Julie [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Michael Burgess, James; Chaplin, Vandiver; Goldstein, Adam; Guiriec, Sylvain; Preece, Robert D. [CSPAR, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Granot, Jonathan [Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Tierney, David, E-mail: lin198361@gmail.com [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

    2011-10-10

    The Swift/Burst Alert Telescope detected the first burst from 1E 1841-045 in 2010 May with intermittent burst activity recorded through at least 2011 July. Here we present Swift and Fermi/Gamma-ray Burst Monitor observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T {sub 90} durations of the bursts range between 18 and 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 10{sup 38} erg, which is on the low side of soft gamma repeater bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in 1E 1841-045 might not involve large-scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  10. Airborne microwave remote sensing of soil moisture

    E-print Network

    Black, Quentin Robert

    1980-01-01

    Subject: Electrical Engineering AIRBORNE MICROWAVE REMOTE SENSING OF SOIL MOISTURE A Thesis by QUENTIN ROBERT BLACK ' Approved as to style and content by: Chairman of Committee ember P~~~ Member Mm er ad of De par tmen t December 1980 ABSTRACT... Airborne Microwave Remote Sensing of Soil Moisture (August 1980) (}uentin Robert Black, B. S. , Texas AEM University Chairman of Advisory Committee: Dr. Richard W. Newton Studies of the theory of microwave emissions from moist soil and experimental...

  11. Anomalous is ubiquitous

    SciTech Connect

    Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il [Department of Technology Management, Holon Institute of Technology, P.O. Box 305, Holon 58102 (Israel); Klafter, Joseph, E-mail: klafter@post.tau.ac.il [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2011-09-15

    Brownian motion is widely considered the quintessential model of diffusion processes-the most elemental random transport processes in Science and Engineering. Yet so, examples of diffusion processes displaying highly non-Brownian statistics-commonly termed 'Anomalous Diffusion' processes-are omnipresent both in the natural sciences and in engineered systems. The scientific interest in Anomalous Diffusion and its applications is growing exponentially in the recent years. In this Paper we review the key statistics of Anomalous Diffusion processes: sub-diffusion and super-diffusion, long-range dependence and the Joseph effect, Levy statistics and the Noah effect, and 1/f noise. We further present a theoretical model-generalizing the Einstein-Smoluchowski diffusion model-which provides a unified explanation for the prevalence of Anomalous Diffusion statistics. Our model shows that what is commonly perceived as 'anomalous' is in effect ubiquitous. - Highlights: > The article provides an overview of Anomalous Diffusion (AD) statistics. > The Einstein-Smoluchowski diffusion model is extended and generalized. > The generalized model universally generates AD statistics. > A unified 'universal macroscopic explanation' for AD statistics is established. > AD statistics are shown to be fundamentally connected to robustness.

  12. An automated analysis of DEMETER ionospheric plasma waves observations and its application to the search for anomalous emissions over the Great Sichuan EQ region

    NASA Astrophysics Data System (ADS)

    Onishi, Tatsuo; Berthelier, Jean-Jacques

    2010-05-01

    Electric field observations in the VLF range from the ICE experiment onboard the CNES DEMETER micro-satellite have been analyzed to search for anomalies possibly related to the Great Sichuan Earthquake of May 12, 2008. This work was undertaken using results from a dedicated data processing that has been recently developed at LATMOS to perform an automated recognition and characterization of the various wave emissions that are regularly detected along the orbit of DEMETER. The data processing method and the associated algorithms will be first presented and a few typical results will be shown in order to provide a detailed understanding of the algorithm capabilities. As a first full-scale application of this method, a statistical study was conducted to analyze the plasma waves observed in day-time half orbits over a region of ~1000 kilometres extent centred on the Sichuan EQ epicentre and during a period of 20 days encompassing the day of the EQ. 5 years of observations have been used to derive the statistical distribution of various types of ionospheric plasma waves that can be compared to the signals detected during the seismic active period. The first outcome of our study was the detection of a localized variation in the characteristics of the electrostatic turbulence 6 days before the EQ that appears to be unique in the whole 5 year reference observations data base. We will discuss this result and its possible interpretations.

  13. Observations of Microwave Fine Structures by the Badary Broadband Microwave Spectropolarimeter and the Siberian Solar Radio Telescope

    NASA Astrophysics Data System (ADS)

    Zhdanov, D. A.; Zandanov, V. G.

    2015-01-01

    Observations of solar radio bursts with fine temporal and spectral structures may provide important information about the physical processes occurring in the solar corona. The Badary Broadband Microwave Spectropolarimeter instrument has been regularly observing solar radio emission in the 3.8 - 8.2 GHz range since August 2010. We present the statistical analysis of spectral and temporal fine structures of microwave emission during solar flares that occurred in 2011 - 2012. Fine structures were detected both during solar flares accompanied by microwave broadband emission and during weak solar flares when the microwave broadband emission was absent. A total of 235 events of solar origin were found and analyzed.

  14. Interpretation of observed cosmic microwave background radiation

    Microsoft Academic Search

    STEPHEN POLLAINE

    1978-01-01

    The Alfven and Mendis (1977) conclusion that dust grains in galaxies render the universe opaque to cosmic microwave background at a red shift ratio equal to 40 is challenged by a calculation of the opacity of galactic dust grains to the microwave background radiation from the time of decoupling at emission red shift ratio equal to 1500 to the present

  15. Microwave Ovens

    MedlinePLUS

    Microwave Ovens RadTown USA Topics Personal Exposure : Airport Security Scanning Cosmic Radiation During Flights X-Rays in CT Scans Dental X-ray Diagnostic Nuclear Medicine Electromagnetic Fields from Power Lines Internal Radiotherapy ...

  16. A New Neural Network Approach Including First-Guess for Retrieval of Atmospheric Water Vapor, Cloud Liquid Water Path, Surface Temperature and Emissivities Over Land From Satellite Microwave Observations

    NASA Technical Reports Server (NTRS)

    Aires, F.; Prigent, C.; Rossow, W. B.; Rothstein, M.; Hansen, James E. (Technical Monitor)

    2000-01-01

    The analysis of microwave observations over land to determine atmospheric and surface parameters is still limited due to the complexity of the inverse problem. Neural network techniques have already proved successful as the basis of efficient retrieval methods for non-linear cases, however, first-guess estimates, which are used in variational methods to avoid problems of solution non-uniqueness or other forms of solution irregularity, have up to now not been used with neural network methods. In this study, a neural network approach is developed that uses a first-guess. Conceptual bridges are established between the neural network and variational methods. The new neural method retrieves the surface skin temperature, the integrated water vapor content, the cloud liquid water path and the microwave surface emissivities between 19 and 85 GHz over land from SSM/I observations. The retrieval, in parallel, of all these quantities improves the results for consistency reasons. A data base to train the neural network is calculated with a radiative transfer model and a a global collection of coincident surface and atmospheric parameters extracted from the National Center for Environmental Prediction reanalysis, from the International Satellite Cloud Climatology Project data and from microwave emissivity atlases previously calculated. The results of the neural network inversion are very encouraging. The r.m.s. error of the surface temperature retrieval over the globe is 1.3 K in clear sky conditions and 1.6 K in cloudy scenes. Water vapor is retrieved with a r.m.s. error of 3.8 kg/sq m in clear conditions and 4.9 kg/sq m in cloudy situations. The r.m.s. error in cloud liquid water path is 0.08 kg/sq m . The surface emissivities are retrieved with an accuracy of better than 0.008 in clear conditions and 0.010 in cloudy conditions. Microwave land surface temperature retrieval presents a very attractive complement to the infrared estimates in cloudy areas: time record of land surface temperature will be produced.

  17. Improvement of the emission properties from InGaN/GaN dot-in-a-wire nanostructures after treatment in the flowing afterglow of a microwave N2 plasma

    NASA Astrophysics Data System (ADS)

    Afonso Ferreira, J.; Nguyen, H. P. T.; Mi, Z.; Leonelli, R.; Stafford, L.

    2014-10-01

    Nominally pure GaN nanowires (NWs) and InGaN/GaN dot-in-a-wire heterostructures were exposed to the flowing afterglow of a N2 microwave plasma and characterized by photoluminescence (PL) spectroscopy. While the band-edge emission from GaN NWs and the GaN matrix of the InGaN/GaN NWs strongly decreased due to the creation of non-radiative recombination centers in the near-surface region, the emission from the InGaN dots strongly increased. PL excitation measurements indicate that such an increase cannot be explained by a plasma-induced shift of the GaN absorption edge. It is rather ascribed to the passivation of grown-in defects and dynamic annealing due to the presence of plasma-generated N atoms and N2 metastables without excessive introduction of ion-induced damage.

  18. Improvement of the emission properties from InGaN/GaN dot-in-a-wire nanostructures after treatment in the flowing afterglow of a microwave N? plasma.

    PubMed

    Ferreira, J Afonso; Nguyen, H P T; Mi, Z; Leonelli, R; Stafford, L

    2014-10-31

    Nominally pure GaN nanowires (NWs) and InGaN/GaN dot-in-a-wire heterostructures were exposed to the flowing afterglow of a N2 microwave plasma and characterized by photoluminescence (PL) spectroscopy. While the band-edge emission from GaN NWs and the GaN matrix of the InGaN/GaN NWs strongly decreased due to the creation of non-radiative recombination centers in the near-surface region, the emission from the InGaN dots strongly increased. PL excitation measurements indicate that such an increase cannot be explained by a plasma-induced shift of the GaN absorption edge. It is rather ascribed to the passivation of grown-in defects and dynamic annealing due to the presence of plasma-generated N atoms and N2 metastables without excessive introduction of ion-induced damage. PMID:25299752

  19. A new microwave spectroscope

    E-print Network

    Salis, Andrew E.

    1951-01-01

    A NEW MICROWAVE SPECTROSCOPE A Dissertation By Andrew E. Sail* June 1951 Approved as to style and content by Chairman of Com ttee A NEW MICROWAVE SPECTROSCOPE A Dissertation Submitted to the Faculty of the Agricultural and Mechanical.... THEORETICAL APPROACH TO THE DESIGNING OP A MICROWAVE SPECTROSCOPE .................... 7 III. DESIGN OF THE EXPERIMENTAL MICROWAVE SPECTROSCOPE .......................... 14 Microwave Source .............................. 17 Microwave Circuit...

  20. Anomalous law of cooling.

    PubMed

    Lapas, Luciano C; Ferreira, Rogelma M S; Rubí, J Miguel; Oliveira, Fernando A

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics. PMID:25770525

  1. Anomalous gauge boson interactions

    SciTech Connect

    Aihara, H. [Lawrence Berkeley Lab., CA (United States); Barklow, T. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Baur, U. [State Univ. of New York, Buffalo, NY (United States). Dept. of Physics]|[Florida State Univ., Tallahassee, FL (United States). Dept. of Physics] [and others

    1995-03-01

    We discuss the direct measurement of the trilinear vector boson couplings in present and future collider experiments. The major goals of such experiments will be the confirmation of the Standard Model (SM) predictions and the search for signals of new physics. We review our current theoretical understanding of anomalous trilinear gauge-boson self interactions. If the energy scale of the new physics is {approximately} 1 TeV, these low energy anomalous couplings are expected to be no larger than {Omicron}(10{sup {minus}2}). Constraints from high precision measurements at LEP and low energy charged and neutral current processes are critically reviewed.

  2. Microwave furnace having microwave compatible dilatometer

    DOEpatents

    Kimrey, H.D. Jr.; Janney, M.A.; Ferber, M.K.

    1992-03-24

    An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy. 2 figs.

  3. Microwave furnace having microwave compatible dilatometer

    DOEpatents

    Kimrey, Jr., Harold D. (Knoxville, TN); Janney, Mark A. (Knoxville, TN); Ferber, Mattison K. (Oak Ridge, TN)

    1992-01-01

    An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a sample by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension of the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy.

  4. Constraint on the Polarization of Electric Dipole Emission from Spinning Dust

    NASA Astrophysics Data System (ADS)

    Hoang, Thiem; Lazarian, A.; Martin, P. G.

    2013-12-01

    Planck results have revealed that the electric dipole emission from polycyclic aromatic hydrocarbons (PAHs) is the most reliable explanation for the anomalous microwave emission that interferes with cosmic microwave background (CMB) radiation experiments. The emerging question is to what extent this emission component contaminates the polarized CMB radiation. We present constraints on polarized dust emission for the model of grain-size distribution and grain alignment that best fits the observed extinction and polarization curves. Two stars with a prominent polarization feature at ? = 2175 Å—HD 197770 and HD 147933-4—are chosen for our study. For HD 197770, we find that the model with aligned silicate grains plus weakly aligned PAHs can successfully reproduce the 2175 Å polarization feature; in contrast, for HD 147933-4, we find that the alignment of only silicate grains can account for that feature. The alignment function of PAHs for the best-fit model to the HD 197770 data is used to constrain polarized spinning dust emission. We find that the degree of polarization of spinning dust emission is about 1.6% at frequency ? ? 3 GHz and declines to below 0.9% for ? > 20 GHz. We also predict the degree of polarization of thermal dust emission at 353 GHz to be P em ? 11% and 14% for the lines of sight to the HD 197770 and HD 147933-4 stars, respectively.

  5. Anomalous Skin Effect Igor Kaganovich

    E-print Network

    Kaganovich, Igor

    Anomalous Skin Effect Revisited Igor Kaganovich Princeton Plasma Physics Laboratory #12 to explain "simply" anomalous skin effect without abusing physics. #12;3 Outline Skin effect (Inductively Coupled Plasmas/ Lasers) ­ Normal skin effect ­ Concept of phase-mixing and scale ­ Anomalous skin effect

  6. Anomalous Reading of Hygrometer

    Microsoft Academic Search

    1910-01-01

    MR. RICHARDSON'S explanation in NATURE of April 28 of the anomalous readings referred to does not seem very satisfactory, because, owing to the presence of dust in the atmosphere, the air is never supersaturated; indeed, it is seldom even saturated, owing to the presence of some particles having an affinity for water vapour. But even supposing there had been supersaturated

  7. Anomalous Reading of Hygrometer

    Microsoft Academic Search

    J. Rowland

    1910-01-01

    ON June II I observed a case of the wet-bulb thermometer reading higher than the dry bulb, which cannot be attributed to a falling temperature, as this anomalous condition continued for more than two hours, during the greater part of which the temperature was slowly rising. A gradually dispersing fog prevailed at the time, and the dry bulb was at

  8. The generation of rapid solar flare hard X-ray and microwave fluctuations in current sheets

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    1986-01-01

    The generation of rapid fluctuations, or spikes, in hard X-ray and microwave bursts via the disruption of electron heating and acceleration in current sheets is studied. It is found that 20 msec hard X-ray fluctuations can be thermally generated in a current sheet if the resistivity in the sheet is highly anomalous, the plasma density in the emitting region is relatively high, and the volume of the emitting region is greater than that of the current sheet. A specific mechanism for producing the fluctuations, involving heating in the presence of ion acoustic turbulence and a constant driving electric field, and interruption of the heating by a strong two-stream instability, is discussed. Variations upon this mechanism are also discussed. This mechanism also modulates electron acceleration, as required for the microwave spike emission. If the hard X-ray emission at energies less than approx. 1000 keV is nonthermal bremsstrahlung, the coherent modulation of electron acceleration in a large number of current sheets is required.

  9. Improving the model of emission from spinning dust: effects of grain wobbling and transient spin-up

    E-print Network

    Hoang, Thiem; Lazarian, A

    2010-01-01

    Observations continue to support the interpretation of the anomalous microwave foreground as electric dipole radiation from spinning dust grains as proposed by Draine and Lazarian (1998ab). In this paper we present a refinement of the original model by improving the treatment of a number of physical effects. First, we consider a disk-like grain rotating with angular velocity at an arbitrary angle with respect to the grain symmetry axis and derive the rotational damping and excitation coefficients arising from infrared emission, plasma-grain interactions and electric dipole emission. The angular velocity distribution and the electric dipole emission spectrum for grains is calculated using the Langevin equation, for cases both with and without fast internal relaxation. Our results show that, the peak emissivity of spinning dust, compared to earlier studies, increases by a factor of ~2 for the Warm Neutral Medium (WNM), the Warm Ionized Medium (WIM), the Cold Neutral Medium (CNM) and the Photodissociation Region...

  10. L-band Microwave Emission of the Biosphere (L-MEB) Model: Description and calibration against experimental data sets over crop fields

    Microsoft Academic Search

    J.-P. Wigneron; Y. H. Kerr; P. Waldteufel; K. Saleh; M.-J. Escorihuela; P. Richaume; P. Ferrazzoli; P. de Rosnay; R. Gurney; J.-C. Calvet; J. P. Grant; M. Guglielmetti; B. Hornbuckle; C. Mätzler; T. Pellarin; M. Schwank

    2007-01-01

    In the near future, the SMOS (Soil Moisture and Ocean Salinity) mission will provide global maps of surface soil moisture (SM). The SMOS baseline payload is an L-band (1.4 GHz) two dimensional interferometric microwave radiometer which will provide multi-angular and dual-polarization observations. In the framework of the ground segment activities for the SMOS mission an operational SMOS Level 2 Soil Moisture

  11. Anomalous radiative transitions

    E-print Network

    Kenzo Ishikawa; Toshiki Tajima; Yutaka Tobita

    2014-09-30

    Anomalous transitions involving photons derived by many-body interaction of the form, $\\partial_{\\mu} G^{\\mu}$, in the standard model are studied. This does not affect the equation of motion in the bulk, but makes wave functions modified, and causes the unusual transition characterized by the time-independent probability. In the transition probability at a time-interval $T$ expressed generally in the form $P=T \\Gamma_0 +P^{(d)}$, now with $ P^{(d)} \

  12. AMSR-E Global Anomalous Sea Surface Temperature Data Used to Forecast 2003 Hurricane Season

    NSDL National Science Digital Library

    Lori Perkins

    2003-06-23

    This animation show a year in the life of anomalous global ocean temperatures, June 2, 2002 to May 11, 2003. Green indicates the coolest water, yellow the warmest. The Advanced Microwave Scanning Radiometer (AMSR-E) on the Aqua satellite saw through the clouds to provide this sea surface temperature data.

  13. FROM THE CURRENT LITERATURE: Negative-energy waves and the anomalous Doppler effect

    Microsoft Academic Search

    M. V. Nezlin

    1976-01-01

    A 'profound' physical analogy between two sets of phenomena hitherto studied independently - negative-energy waves (NEW) in dispersive media and the anomalous Doppler effect (ADE) - is probed. The NEW phenomenon is defined (frequency derivative of product of frequency-dependent permittivity times frequency negative) and relations between NEW and dispersion, electron beam (EB), plasma instability, and microwave slow-wave structure phenomena are

  14. Compact Microwave Fourier Spectrum Analyzer

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  15. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1989-01-01

    This paper discusses the following topics on microwave processing of ceramics: Microwave-material interactions; anticipated advantage of microwave sintering; ceramic sintering; and ceramic joining. 24 refs., 4 figs. (LSP)

  16. An Anomalous Force on the Map Spacecraft

    NASA Technical Reports Server (NTRS)

    Starin, Scott R.; ODonnell, James R., Jr.; Ward, David K.; Wollack, Edward J.; Bay, P. Michael; Fink, Dale R.; Bauer, Frank (Technical Monitor)

    2002-01-01

    The Microwave Anisotropy Probe (MAP) orbits the second Earth-Sun libration point (L2)-about 1.5 million kilometers outside Earth's orbit-mapping cosmic microwave background radiation. To achieve orbit near L2 on a small fuel budget, the MAP spacecraft needed to swing past the Moon for a gravity assist. Timing the lunar swing-by required MAP to travel in three high-eccentricity phasing loops with critical maneuvers at a minimum of two, but nominally all three, of the perigee passes. On the approach to the first perigee maneuver, MAP telemetry showed a considerable change in system angular momentum that threatened to cause on-board Failure Detection and Correction (FDC) to abort the critical maneuver. Fortunately, the system momentum did not reach the FDC limit; however, the MAP team did develop a contingency strategy should a stronger anomaly occur before or during subsequent perigee maneuvers, Simultaneously, members of the MAP team developed and tested various hypotheses for the cause of the anomalous force. The final hypothesis was that water was outgassing from the thermal blanketing and freezing to the cold side of the solar shield. As radiation from Earth warmed the cold side of the spacecraft, the uneven sublimation of frozen water created a torque on the spacecraft.

  17. Tandem microwave waste remediation and decontamination system

    DOEpatents

    Wicks, George G. (North Aiken, SC); Clark, David E. (Gainesville, FL); Schulz, Rebecca L. (Gainesville, FL)

    1999-01-01

    The invention discloses a tandem microwave system consisting of a primary chamber in which microwave energy is used for the controlled combustion of materials. A second chamber is used to further treat the off-gases from the primary chamber by passage through a susceptor matrix subjected to additional microwave energy. The direct microwave radiation and elevated temperatures provide for significant reductions in the qualitative and quantitative emissions of the treated off gases. The tandem microwave system can be utilized for disinfecting wastes, sterilizing materials, and/or modifying the form of wastes to solidify organic or inorganic materials. The simple design allows on-site treatment of waste by small volume waste generators.

  18. Experimental study of matrix carbon field-emission cathodes and computer aided design of electron guns for microwave power devices, exploring these cathodes

    SciTech Connect

    Grigoriev, Y.A.; Petrosyan, A.I.; Penzyakov, V.V.; Pimenov, V.G.; Rogovin, V.I.; Shesterkin, V.I.; Kudryashov, V.P.; Semyonov, V.C. [Research Production Co. ALMAZ, Panfilova 1, Saratov 410033 (Russia)] [Research Production Co. ALMAZ, Panfilova 1, Saratov 410033 (Russia)

    1997-03-01

    The experimental study of matrix carbon field-emission cathodes (MCFECs), which has led to the stable operation of the cathodes with current emission values up to 100 mA, is described. A method of computer aided design of TWT electron guns (EGs) with MCFEC, based on the results of the MCFEC emission experimental study, is presented. The experimental MCFEC emission characteristics are used to define the field gain coefficient K and the cathode effective emission area S{sub eff}. The EG program computes the electric field upon the MCFEC surface, multiplies it by the K value and uses the Fowler{endash}Nordheim law and the S{sub eff} value to calculate the MCFEC current; the electron trajectories are computed as well. {copyright} {ital 1997 American Vacuum Society.}

  19. Anomalous Radiation Produced by Glow Discharge in Deuterium Containing Oxygen

    Microsoft Academic Search

    Edmund Storms; Brian Scanlan

    2008-01-01

    ElectroMagnetic Radiation (EMR) and anomalous radiation (potentially produced by nuclear reactions, involving high energy particles), in a low-voltage discharge in a gas containing deuterium was measured using a Geiger counter located within the apparatus. This radiation is found to consist of energetic particles that are produced only when the voltage is above a critical value. In addition, the emission is

  20. ORNL TNS program: microwave start-up of tokamak plasmas near electron cyclotron and upper hybrid resonances

    Microsoft Academic Search

    Y. K. M. Peng; S. K. Borowski

    1977-01-01

    The scenario of toroidal plasma start-up with microwave initiation and heating near the electron cyclotron frequency is suggested and examined here. We assume microwave irradiation from the high field side and an anomalously large absorption of the extraordinary waves near the upper hybrid resonance. The dominant electron energy losses are assumed to be due to magnetic field curvature and parallel

  1. Wideband Agile Digital Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Gaier, Todd C.; Brown, Shannon T.; Ruf, Christopher; Gross, Steven

    2012-01-01

    The objectives of this work were to take the initial steps needed to develop a field programmable gate array (FPGA)- based wideband digital radiometer backend (>500 MHz bandwidth) that will enable passive microwave observations with minimal performance degradation in a radiofrequency-interference (RFI)-rich environment. As manmade RF emissions increase over time and fill more of the microwave spectrum, microwave radiometer science applications will be increasingly impacted in a negative way, and the current generation of spaceborne microwave radiometers that use broadband analog back ends will become severely compromised or unusable over an increasing fraction of time on orbit. There is a need to develop a digital radiometer back end that, for each observation period, uses digital signal processing (DSP) algorithms to identify the maximum amount of RFI-free spectrum across the radiometer band to preserve bandwidth to minimize radiometer noise (which is inversely related to the bandwidth). Ultimately, the objective is to incorporate all processing necessary in the back end to take contaminated input spectra and produce a single output value free of manmade signals to minimize data rates for spaceborne radiometer missions. But, to meet these objectives, several intermediate processing algorithms had to be developed, and their performance characterized relative to typical brightness temperature accuracy re quirements for current and future microwave radiometer missions, including those for measuring salinity, soil moisture, and snow pack.

  2. Flashing anomalous color contrast

    PubMed Central

    Pinna, Baingio; Spillmann, Lothar; Werner, John S.

    2008-01-01

    A new visual phenomenon that we call flashing anomalous color contrast is described. This phenomenon arises from the interaction between a gray central disk and a chromatic annulus surrounded by black radial lines. In an array of such figures, the central gray disk no longer appears gray, but assumes a color complementary to that of the surrounding annulus. The induced color appears: (1) vivid and saturated; (2) self-luminous, not a surface property; (3) flashing with eye or stimulus movement; (4) floating out of its confines; and (5) stronger in extrafoveal than in foveal vision. The strength of the effect depends on the number, length, width, and luminance contrast of the radial lines. The results suggest that the chromatic ring bounding the inner tips of the black radial lines induces simultaneous color contrast, whereas the radial lines elicit, in conjunction with the gray disk and the ring, the flashing, vividness, and high saturation of the effect. The stimulus properties inducing the illusion suggest that flashing anomalous color contrast may be based on asynchronous interactions among multiple visual pathways. PMID:15518215

  3. Speciation analysis of triethyl-lead and tributyl-tin compounds in human urine by liquid-liquid extraction and gas chromatography microwave-induced plasma atomic emission detection.

    PubMed

    Zachariadis, George A; Rosenberg, Erwin

    2012-05-01

    This work describes the development of a fast method for speciation analysis of triethyl-lead and tributyl-tin species in urine samples after in situ derivatization by tetraethyl- or tetrapropyl-borate reagents. The alkylation reaction is done in the aqueous and urine medium and the less-polar derivatives are extracted in hexane by liquid-liquid extraction. The species were extracted and the extract was efficiently collected from the aqueous phase after centrifugation. Finally, the organometallic species are separated by gas chromatography and determined from the emission signals of elemental lead and tin. Atomic lead and tin are formed from the organolead and organotin compounds during atomization of the column eluate in a microwave-induced helium plasma source. The simultaneous measurement of lead (Pb) at 405.780 nm and tin (Sn) at 303.419 nm was achieved by an atomic emission detector. Finally, the analytes were determined with satisfactory precision (<5%) and detection limits of 0.05 ?g Pb/L and 0.48 ?g Sn/L, respectively, when 10 mL of urine is extracted with 1 mL of hexane and 1 ?L of extract is injected. PMID:22689489

  4. Localised Microwave Bursts During ELMs on MAST

    NASA Astrophysics Data System (ADS)

    Freethy, Simon; Shevchenko, Vladimir; Huang, Billy; Vann, Roddy

    2015-03-01

    Bursts of microwave emission are observed during ELM events on the Mega Ampère Spherical Tokamak. In agreement with observations on other machines, these bursts are up to 3 orders of magnitude more intense than the thermal background, but are electron cyclotron in nature. The peak in microwave emission is ~20? before the peak in midplane D? emission. Using the Synthetic Aperture Microwave Imaging radiometer, we are able to demonstrate that these bursts are often highly spatially localised and preferentially occur at the tokamak midplane. It is hypothesised that the localisation is a result of Doppler resonance broadening for electron Bernstein waves and the high perpendicular electron energies could be the result of pitch angle scattering in high collisionality regions of the plasma.

  5. The Upper Atmosphere Research Satellite Microwave Limb Sounder Instrument

    Microsoft Academic Search

    F. T. Barath; M. C. Chavez; R. E. Cofield; D. A. Flower; M. A. Frerking; M. B. Gram; W. M. Harris; J. R. Holden; R. F. Jarnot; W. G. Kloezeman; G. J. Klose; G. K. Lau; M. S. Loo; B. J. Maddison; R. J. Mattauch; R. P. McKlnney; G. E. Peckham; H. M. Pickett; G. Siebes; F. S. Soltis; R. A. Suttie; J. A. Tarsala; J. W. Waters; W. J. Wilson

    1993-01-01

    The microwave limb sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) is the first satellite experiment using limb sounding techniques at microwave frequencies. Primary measure- ment objectives are stratospheric C10, 03, H20, temperature, and pressure. Measurements are of thermal emission: all are performed simultaneously and continuously and are not degraded by ice clouds or volcanic aerosols. The instrument has

  6. Antenna Pattern Synthesis and Deconvolution of Microwave Radiometer Imaging Data

    E-print Network

    Reising, Steven C.

    Antenna Pattern Synthesis and Deconvolution of Microwave Radiometer Imaging Data C. T. Swift, M. A. Introduction A microwave radiometer measures the actual thermal emission smoothed by the radiation power radiometers. The first conically scanned space borne radiometer system for earth remote sensing was the SMMR

  7. THE EFFECTS OF MICROWAVE RADIATION FROM TELECOMMUNICATION BASE STATIONS

    Microsoft Academic Search

    Douglas J. G. Ford

    This is not an exhaustive study. It is a review of some of the published literature on the effects of microwaves, radio waves (RF) and electro-magnetic fields (EMF). Evidence is presented that emissions from microwave base stations do have effects on those living nearby. Studies on animals that demonstrate possible mechanisms for those effects are also discussed. Evidence is also

  8. Refinement of a semi-empirical model for the microwave emissivity of the sea surface as a function of wind speed

    E-print Network

    Kohn, David Jacob

    1995-01-01

    the computed emissivity of the sea surface-, which is more representative of observations without sea foam. The second change is made to the sea surface roughness parameter. An increase in roughness is needed at frequencies above 16.6 GHz and a decrease below...

  9. GIANT RINGS IN THE COSMIC MICROWAVE BACKGROUND SKY

    SciTech Connect

    Kovetz, Ely D.; Ben-David, Assaf; Itzhaki, Nissan, E-mail: elykovetz@gmail.co, E-mail: bd.assaf@gmail.co, E-mail: nitzhaki@post.tau.ac.i [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Ramat-Aviv, 69978 (Israel)

    2010-11-20

    We find a unique direction in the cosmic microwave background sky around which giant rings have an anomalous mean temperature profile. This direction is in very close alignment with the afore measured anomalously large bulk flow direction. Using Monte Carlo simulations, we estimate the significance of the giant rings at the 3{sigma} level and the alignment with the bulk flow at 2.5{sigma}. We argue that a cosmic defect seeded by a pre-inflationary particle could explain the giant rings, the large bulk flow, and their alignment.

  10. X-ray Anomalous Scattering

    NSDL National Science Digital Library

    This University of Washington Web site "is intended to serve both as an introductory tutorial to anomalous scattering and as a general tool for designing experiments based on anomalous scattering." Visitors can find a periodic table and a chart supplying X-ray absorption edge data. Students needing assistance with the concept of anomalous scattering will find the tutorial explaining the interactions of incident photons having relatively high and low energy with scattering electrons very instructive. The site also supplies users with information about Friedel's Law and MAD experiments.

  11. The Soft XRay/Microwave Ratio of Solar and Stellar Flares and Coronae

    E-print Network

    Guedel, Manuel

    We have carried out plasma diagnostics of solar flares using soft X­ray (SXR) and simultaneous microwave observations and have compared the ratio of X­ray to microwave luminosities of solar flares as thermal radiations of coronal plasmas. On the other hand, the microwave emission of stars and solar flares

  12. Anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Nagaosa, Naoto; Sinova, Jairo; Onoda, Shigeki; MacDonald, A. H.; Ong, N. P.

    2010-04-01

    The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a tentative global view of the AHE is proposed which summarizes the roles played by intrinsic and extrinsic contributions in the disorder strength versus temperature plane. Finally outstanding issues and avenues for future investigation are discussed.

  13. Laboratory measurement of the millimeter wave properties of liquid sulfuric acid (H2SO4). [study of microwave emission from Venus

    NASA Technical Reports Server (NTRS)

    Fahd, Antoine K.; Steffes, Paul G.

    1991-01-01

    The methodology and the results of laboratory measurements of the millimeter wave properties of liquid sulfuric acid are presented. Measurements conducted at 30-40 and 90-100 GHz are reported, using different concentrations of liquid H2SO4. The measured data are used to compute the expected opacity of H2SO4 condensates and their effects on the millimeter wave emission from Venus. The cloud condensate is found to have an effect on the emission from Venus. The calculated decrease in brightness temperature is well below the observed decrease in brightness temperature found by de Pater et al. (1991). It is suggested that other constituents such as gaseous H2SO4 also affect the observed variation in the brightness temperature.

  14. Interpretation of observed cosmic microwave background radiation

    NASA Technical Reports Server (NTRS)

    Pollaine, S.

    1978-01-01

    The Alfven and Mendis (1977) conclusion that dust grains in galaxies render the universe opaque to cosmic microwave background at a red shift ratio equal to 40 is challenged by a calculation of the opacity of galactic dust grains to the microwave background radiation from the time of decoupling at emission red shift ratio equal to 1500 to the present in the standard big bang model. In the present calculation, evolutionary effects on grain opacity and abundance are estimated. At wavelengths used in studying the microwave background, the optical depth of the grains is found to be 0.18 when the deceleration parameter equals 0.03, and 0.05 when the deceleration parameter equals 0.5. The results indicate that microwave background can provide information on an early dense phase of the universe.

  15. The Muon Anomalous Magnetic Moment

    E-print Network

    Marc Knecht

    2014-12-03

    The calculations entering the prediction of the standard model value for the anomalous magnetic moment of the muon $a_\\mu$ are reviewed, and compared to the very accurate experimental measurement. The situation for the electron is discussed in parallel.

  16. Microwave Imaging Reflectometry for the Visualization of Turbulence in Tokamaks

    SciTech Connect

    E. Mazzucato

    1999-12-16

    Understanding the mechanism of anomalous transport in magnetically confined plasmas requires the use of sophisticated diagnostic tools for the measurement of short-scale turbulent fluctuations. This paper describes the conceptual design of an experimental technique for the global visualization of density fluctuations in tokamaks. The proposed method is based on microwave reflectometry and consists in using a large diameter probing beam, collecting the reflected waves with a large aperture antenna, and forming an image of the reflecting plasma layer onto a 2D array of microwave receivers. Based on results from a series of numerical simulations, the theoretical feasibility conditions of the proposed method are discussed.

  17. Anomalous cosmic rays

    NASA Astrophysics Data System (ADS)

    Cummings, Alan C.; Stone, Edward C.

    2013-02-01

    Anomalous cosmic rays (ACRs) first started showing up in observations 40 years ago. Within a few years a paradigm was developed to explain their origin: they begin their life as interstellar neutral atoms that drift into the heliosphere, become singly ionized by chargeexchange with a solar wind ion or by photoionization, are picked up by the expanding solar wind, and accelerated to the observed energies by diffusive shock acceleration at the solar wind termination shock. This paradigm became widely accepted and withstood the tests of further observations until 16 December 2004, when Voyager 1 crossed the termination shock and didn't find their source. In August 2007, Voyager 2 crossed the termination shock and also did not find the source location of ACRs. Clearly, the source location was not at the termination shock where the two Voyagers crossed. Alternative models have been proposed with acceleration elsewhere on the shock or by other acceleration processes in the heliosheath. We discuss the latest observations of ACRs from the Voyager spacecraft and hopefully shed more light on this ongoing puzzle.

  18. Anomalous - viscosity current drive

    DOEpatents

    Stix, Thomas H. (Princeton, NJ); Ono, Masayuki (Princeton Junction, NJ)

    1988-01-01

    An apparatus and method for maintaining a steady-state current in a toroidal magnetically confined plasma. An electric current is generated in an edge region at or near the outermost good magnetic surface of the toroidal plasma. The edge current is generated in a direction parallel to the flow of current in the main plasma and such that its current density is greater than the average density of the main plasma current. The current flow in the edge region is maintained in a direction parallel to the main current for a period of one or two of its characteristic decay times. Current from the edge region will penetrate radially into the plasma and augment the main plasma current through the mechanism of anomalous viscosity. In another aspect of the invention, current flow driven between a cathode and an anode is used to establish a start-up plasma current. The plasma-current channel is magnetically detached from the electrodes, leaving a plasma magnetically insulated from contact with any material obstructions including the cathode and anode.

  19. Microwave plasma torch-atomic emission spectrometry for the on-line determination of rare earth elements based on flow injection preconcentration by TiO2-graphene composite.

    PubMed

    Zhang, Junling; Cheng, Rongmin; Tong, Shanshan; Gu, Xiaowen; Quan, Xinjun; Liu, Yunling; Jia, Qiong; Jia, Jianbo

    2011-10-30

    In this work, we synthesized TiO(2)-graphene composite as a novel preconcentration material. It was enclosed in a microcolumn in the on-line flow injection system to adsorb trace light (La), medium (Tb), and heavy (Ho) rare earth elements (REEs) prior to their determinations by microwave plasma torch-atomic emission spectrometry (MPT-AES). Various experimental parameters, such as sample loading time, sample flow rate, sample pH, eluent flow rate, eluent concentration, and interfering ions, were investigated systematically. Under the optimum conditions, the detection limits (three times of standard deviations of blank by 7 reiterations) of La, Tb, and Ho were found to be 2.2, 1.6, and 2.8 ?g L(-1), with enrichment factors of 17.1, 11.1, and 10.2, respectively. Relative standard deviations for the determination of the target REEs were 3.6%, 1.3%, and 1.4%, respectively (n=7). The developed method was validated by the analysis of La, Tb, and Ho in certified reference material (GBW07313, marine sediment) and high purity REE oxide samples. PMID:22063519

  20. Petrology of Anomalous Eucrites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Peng, Z. X.; Ross, D. K.

    2015-01-01

    Most mafic achondrites can be broadly categorized as being "eucritic", that is, they are composed of a ferroan low-Ca clinopyroxene, high-Ca plagioclase and a silica phase. They are petrologically distinct from angritic basalts, which are composed of high-Ca, Al-Ti-rich clinopyroxene, Carich olivine, nearly pure anorthite and kirschsteinite, or from what might be called brachinitic basalts, which are composed of ferroan orthopyroxene and high-Ca clinopyroxene, intermediate-Ca plagioclase and ferroan olivine. Because of their similar mineralogy and composition, eucrite-like mafic achondrites formed on compositionally similar asteroids under similar conditions of temperature, pressure and oxygen fugacity. Some of them have distinctive isotopic compositions and petrologic characteristics that demonstrate formation on asteroids different from the parent of the HED clan (e.g., Ibitira, Northwest Africa (NWA) 011). Others show smaller oxygen isotopic distinctions but are otherwise petrologically and compositionally indistinguishable from basaltic eucrites (e.g., Pasamonte, Pecora Escarpment (PCA) 91007). The degree of uniformity in delta O-17 of eucrites and diogenites is one piece of evidence considered to favor of a magma-ocean scenario for their petrogenesis. Given that the O isotopic differences separating Pasamonte and PCA 91007 from other eucrites are small, and that there is an absence of other distinguishing characteristics, a legitimate question is: Did the HED parent asteroid fail to homogenize via a magma-ocean stage, thus explaining outliers like Pasamonte? We are initiating a program of study of anomalous eucrite-like achondrites as one part of our effort to seek a resolution of this issue. Here we present preliminary petrologic information on Asuka (A-) 881394, Elephant Moraine (EET) 87520 and EET 87542. We will have studied several more by conference time.

  1. Intersunspot Microwave Sources

    NASA Astrophysics Data System (ADS)

    Bakunina, I. A.; Melnikov, V. F.; Solov'ev, A. A.; Abramov-Maximov, V. E.

    2015-01-01

    We studied a number of solar active regions using two-dimensional spatially resolved microwave observations. Data from the Nobeyama Radioheliograph and the Siberian Solar Radio Telescope together with observations by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) have allowed us to identify long-lived intersunspot sources (ISSs) in most of the investigated active regions. Their centers are often located above the line-of-sight magnetic field inversion line that separates the leading and following polarities of a full active region (first type of ISS) or above the inversion line that separates magnetic polarities inside of a complex of sunspots (second type of ISS). ISSs of the first type are extended and, in general, they are sources of bremsstrahlung emission. ISSs of the second type are compact and are, most likely, sources of gyroresonance or gyrosynchrotron emission. We propose a qualitative model involving three types of magnetic connectivity to explain how long-lasting ISSs may be generated.

  2. Measurements of human body microwave radiation

    Microsoft Academic Search

    G. V. Ponezha; S. G. Ponezha; A. I. Nizhelskaya

    2003-01-01

    Major problems of registering microwave radiation of human body have been considered. It is pointed out that they are caused by at least three factors which may considerably influence the experimental results and their interpretation, namely: (1) properties of the radiation (their low intensity primarily); (2) features of measurements that implement waveguide techniques; (3) peculiar features of the emission medium

  3. Polarized Emission from Interstellar Dust

    E-print Network

    John E. Vaillancourt

    2006-09-01

    Observations of far-infrared (FIR) and submillimeter (SMM) polarized emission are used to study magnetic fields and dust grains in dense regions of the interstellar medium (ISM). These observations place constraints on models of molecular clouds, star-formation, grain alignment mechanisms, and grain size, shape, and composition. The FIR/SMM polarization is strongly dependent on wavelength. We have attributed this wavelength dependence to sampling different grain populations at different temperatures. To date, most observations of polarized emission have been in the densest regions of the ISM. Extending these observations to regions of the diffuse ISM, and to microwave frequencies, will provide additional tests of grain and alignment models. An understanding of polarized microwave emission from dust is key to an accurate measurement of the polarization of the cosmic microwave background. The microwave polarization spectrum will put limits on the contributions to polarized emission from spinning dust and vibrating magnetic dust.

  4. Microwave radiometry and applications

    NASA Astrophysics Data System (ADS)

    Polívka, Ji?í

    1995-09-01

    The radiometry in general is a method of detecting the radiation of matter. All material bodies and substances radiate energy in the form of electromagnetic waves according to Planck s Law. The frequency spectrum of such thermal radiation is determined, beyond the properties of a blackbody, by the emissivity of surfaces and by the temperature of a particular body. Also, its reflectivity and dispersion take part. Investigating the intensity of radiation and its spectral distribution, one may determine the temperature and characterize the radiating body as well as the ambient medium, all independently of distance. With the above possibilities, the radiometry represents a base of scientific method called remote sensing. Utilizing various models, temperature of distant bodies and images of observed scenes can be determined from the spatial distribution of radiation. In this method, two parameters are of paramount importance: the temperature resolution, which flows out from the detected energy, and the spatial resolution (or, angular resolution), which depends upon antenna size with respect to wavelength. An instrument usable to conduct radiometric observations thus consists of two basic elements: a detector or radiometer, which determines the temperature resolution, and an antenna which determines the angular or spatial resolution. For example, a photographic camera consists of an objective lens (antenna) and of a sensitive element (a film or a CCD). In remote sensing, different lenses and reflectors and different sensors are employed, both adjusted to a particular spectrum region in which certain important features of observed bodies and scenes are present: frequently, UV and IR bands are used. The microwave radiometry utilizes various types of antennas and detectors and provides some advantages in observing various scenes: the temperature resolution is recently being given in milikelvins, while the range extends from zero to millions of Kelvins. Microwaves also offer a chance to penetrate surfaces of non-metallic objects down to some wavelengths, by which it is advantageous in certain applications over e.g. IR waves. An extreme example of capabilities of the microwave radiometry is found in radio astronomy, where it determines temperatures and spectral features of bodies so remote that their distance from us is measured in millions of light years. Other apparatus serve in remote observation of Earth s resources: soils, water regions and atmosphere. Similar systems also have found applications in medical studies of human body, e.g. in cancer and inflammation diagnostics. The paper presents a background of the radiometric method, comments to equipment design and outlines some of the applications.

  5. Anomalous transport with overlap fermions

    NASA Astrophysics Data System (ADS)

    Buividovich, P. V.

    2014-05-01

    Anomalous correlators of vector and axial currents which enter the Kubo formulae for the chiral magnetic and the chiral separation conductivities are explicitly calculated for free overlap fermions on the lattice. The results are confronted with continuum calculations in the finite-temperature regularization, and a subtle point of such regularization for chiral magnetic conductivity related to the correct counting of the chiral states is highlighted. In agreement with some previous claims in the literature, we find that in a lattice regularization which respects gauge invariance, the chiral magnetic conductivity vanishes. We point out that the relation of anomalous transport coefficients to axial anomaly is nontrivial due to the non-commutativity of their infrared limit and the Taylor expansion in baryon or chiral chemical potential. In particular, we argue that the vector and axial Ward identities fix the asymptotic behavior of anomalous current-current correlators in the limit of large momenta. Basing on the work of Knecht et al. on the perturbative non-renormalization of the transverse part of the correlator of two vector and one axial currents, we demonstrate that the relation of the anomalous vector-vector correlator to axial anomaly holds perturbatively in massless QCD but might be subject to non-perturbative corrections. Finally, we identify kinematical regimes in which the anomalous transport coefficients can be extracted from lattice measurements.

  6. Color sensing under microwaves

    NASA Astrophysics Data System (ADS)

    Choudhury, Debesh

    2013-09-01

    Inspired by recent results of artificial color due to Caulfield, we carry out intuitive experimental investigations on color sensing under microwave illumination. Experiemnts have been carried out using a Gunn diode as the microwave source and a microwave diode as a detector. More precise experimental studies have also been carried out utilizing a vector network analyzer. Preliminary results of the experiments validate the feasibility of sensing and discriminating otherwise visual colors under microwave illumination. Caulfield's presumption possibly paves the way for artificial color perception using microwaves.

  7. Microwave Remote Sensing Resources

    NSDL National Science Digital Library

    COMET

    2007-04-20

    This module provides background information on microwave remote sensing with polar-orbiting satellites. It reviews coverage, orbits, and data latency issues of current operational and selected research satellites and notes improvements expected in the NPP and NPOESS era. The module contrasts active vs. passive remote sensing, discusses advantages and limitations of different microwave instrument scanning strategies, and addresses viewing geometry with implications for spatial resolution and swath coverage. Finally, it offers a review of the microwave spectrum and special characteristics of microwave energy important for understanding microwave imagery and derived products. This module takes about 1 hour to complete.

  8. High brightness microwave lamp

    DOEpatents

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  9. Microwave hemorrhagic stroke detector

    DOEpatents

    Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

    2002-01-01

    The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stroke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

  10. Microwave hemorrhagic stroke detector

    DOEpatents

    Haddad, Waleed S. (Dublin, CA); Trebes, James E. (Livermore, CA)

    2007-06-05

    The microwave hemorrhagic stroke detector includes a low power pulsed microwave transmitter with a broad-band antenna for producing a directional beam of microwaves, an index of refraction matching cap placed over the patients head, and an array of broad-band microwave receivers with collection antennae. The system of microwave transmitter and receivers are scanned around, and can also be positioned up and down the axis of the patients head. The microwave hemorrhagic stroke detector is a completely non-invasive device designed to detect and localize blood pooling and clots or to measure blood flow within the head or body. The device is based on low power pulsed microwave technology combined with specialized antennas and tomographic methods. The system can be used for rapid, non-invasive detection of blood pooling such as occurs with hemorrhagic stoke in human or animal patients as well as for the detection of hemorrhage within a patient's body.

  11. Catastrophic extraction of anomalous events

    NASA Astrophysics Data System (ADS)

    Jannson, Tomasz; Forrester, Thomas; Ro, Sookwang; Kostrzewski, Andrew

    2012-06-01

    In this paper we discuss extraction of anomalous events based on the theory of catastrophes, a mathematical theory of continuous geometrical manifolds with discrete singularities called catastrophes. Intelligence exploitation systems and technologies include such novel data mining techniques as automatic extraction of discrete anomalous events by software algorithms based on the theory of catastrophes, that can reduce complex problems to a few essential so-called state variables. This paper discusses mostly corank-1 catastrophes with only one state variable, for simplicity. As an example we discuss mostly avionics platforms and catastrophic failures that can be recorded by flight instruments.

  12. Discovery of the Microwave Background Cosmic microwave background radiation

    E-print Network

    Barnes, Joshua Edward

    Discovery of the Microwave Background Cosmic microwave background radiation Signals from the early universe, or pigeon droppings? #12;Microwave Background Radiation The spectrum is a near- perfect match energy reaching us from all directions. #12;Origin of the Microwave Background Back at z > 0, microwave

  13. Cosmic microwave background images

    NASA Astrophysics Data System (ADS)

    Herranz, D.; Vielva, P.

    2010-01-01

    Cosmology concerns itself with the fundamental questions about the formation, structure, and evolution of the Universe as a whole. Cosmic microwave background (CMB) radiation is one of the foremost pillars of physical cosmology. Joint analyses of CMB and other astronomical observations are able to determine with ever increasing precision the value of the fundamental cosmological parameters and to provide us with valuable insight about the dynamics of the Universe in evolution. The CMB radiation is a relic of the hot and dense first moments of the Universe: a extraordinarily homogeneous and isotropic blackbody radiation, which shows small temperature anisotropies that are the key for understanding the conditions of the primitive Universe, testing cosmological models and probing fundamental physics at the very dawn of time. CMB observations are obtained by imaging of the sky at microwave wavelengths. However, the CMB signal is mixed with other astrophysical signals of both Galactic and extragalactic origin. To properly exploit the cosmological information contained in CMB images, they must be cleansed of these other astrophysical emissions first. Blind source separation (BSS) has been a very active field in the last few years. Conversely, the term "compact sources" is often used in the CMB literature referring to spatially bounded, small features in the images, such as galaxies and galaxy clusters. Compact sources and diffuse sources are usually treated separately in CMB image processing. We devote this tutorial to the case of compact sources. Many of the compact source-detection techniques that are widespread inmost fields of astronomy are not easily applicable to CMB images. In this tutorial, we present an overview of the fundamentals of compact object detection theory keeping in mind at every moment these particularities. Throughout the article, we briefly consider Bayesian object detection, model selection, optimal linear filtering, nonlinear filtering, and multif- requency detection of compact sources in CMB images. This article's goal is to present a tutorial on the detection, parameter estimation and statistical analysis of compact sources (far galaxies, galaxy clusters, and Galactic dense emission regions) in CMB observations.

  14. Big Bang Leftovers in the Microwave Cosmology with the Cosmic Microwave Background Radiation

    E-print Network

    Gawiser, E

    2000-01-01

    We combine detections of anisotropy in the Cosmic Microwave Background radiation with observations of inhomogeneity in the large-scale distribution of galaxies to test the predictions of models of cosmological structure formation. This combination probes spatial scales varying by three orders of magnitude, including a significant region where the two types of data overlap. We examine Cold Dark Matter models with adiabatic density perturbations, isocurvature models, and a topological defects model. We set upper limits on the neutrino mass and find the primordial power spectrum needed to reconcile an apparent disagreement between structure formation observations and direct observations of cosmological parameters. Present and future observations of Cosmic Microwave Background anisotropy suffer from foreground contamination. We develop detailed predictions for microwave emission from radio and infrared-bright galaxies and the Sunyaev-Zeldovich effect from clusters. We present realistic simulations of the microwav...

  15. Raman lidar calibration for the DMSP SSM\\/T-2 microwave water vapor sensor

    Microsoft Academic Search

    John Wessel; Steven M. Beck; Yat C. Chan; Robert W. Farley; Jerry A. Gelbwachs

    2000-01-01

    Campaigns were conducted at the Pacific Missile Range Facility, Barking Sands, Kauai, investigating Raman lidar as a method to improve calibration of the DMSP SSM\\/T-2 microwave water vapor profiling instrument. Lidar mixing ratios were calibrated against AIR and Vaisala radiosondes and the calibration was tested in the vicinity of clouds. Above 6 km, radiosondes reported anomalously low relative humidity in

  16. Determination of electron temperature of shock-heated plasma from microwave measurements

    Microsoft Academic Search

    A. Singer; J. M. Minkowski

    1973-01-01

    It is shown that the anomalous results reported for microwave measurements of electron temperature of shock-heated plasma in the range of Mach 9.7 to 10.4 were due to an incorrect model for relating the measured plasma parameters to the electron plasma temperature. A corrected model removes the anomaly.

  17. Microwave remote sensing of snowpacks

    NASA Technical Reports Server (NTRS)

    Stiles, W. H.; Ulaby, F. T.

    1980-01-01

    The interaction mechanisms responsible for the microwave backscattering and emission behavior of snow were investigated, and models were developed relating the backscattering coefficient (sigma) and apparent temperature (T) to the physical parameters of the snowpack. The microwave responses to snow wetness, snow water equivalent, snow surface roughness, and to diurnal variations were investigated. Snow wetness was shown to have an increasing effect with increasing frequency and angle of incidence for both active and passive cases. Increasing snow wetness was observed to decrease the magnitude sigma and increase T. Snow water equivalent was also observed to exhibit a significant influence sigma and T. Snow surface configuration (roughness) was observed to be significant only for wet snow surface conditions. Diurnal variations were as large as 15 dB for sigma at 35 GHz and 120 K for T at 37 GHz. Simple models for sigma and T of a snowpack scene were developed in terms of the most significant ground-truth parameters. The coefficients for these models were then evaluated; the fits to the sigma and T measurements were generally good. Finally, areas of needed additional observations were outlined and experiments were specified to further the understanding of the microwave-snowpack interaction mechanisms.

  18. Microwave amplification with nanomechanical resonators

    E-print Network

    F. Massel; T. T. Heikkilä; J. -M. Pirkkalainen; S. U. Cho; H. Saloniemi; P. Hakonen; M. A. Sillanpää

    2011-07-25

    Sensitive measurement of electrical signals is at the heart of modern science and technology. According to quantum mechanics, any detector or amplifier is required to add a certain amount of noise to the signal, equaling at best the energy of quantum fluctuations. The quantum limit of added noise has nearly been reached with superconducting devices which take advantage of nonlinearities in Josephson junctions. Here, we introduce a new paradigm of amplification of microwave signals with the help of a mechanical oscillator. By relying on the radiation pressure force on a nanomechanical resonator, we provide an experimental demonstration and an analytical description of how the injection of microwaves induces coherent stimulated emission and signal amplification. This scheme, based on two linear oscillators, has the advantage of being conceptually and practically simpler than the Josephson junction devices, and, at the same time, has a high potential to reach quantum limited operation. With a measured signal amplification of 25 decibels and the addition of 20 quanta of noise, we anticipate near quantum-limited mechanical microwave amplification is feasible in various applications involving integrated electrical circuits.

  19. Microwave Measurements of Coronal Magnetic Field

    NASA Astrophysics Data System (ADS)

    Shibasaki, K.

    2006-08-01

    Magnetic field measurements of the solar corona using microwave observation are reviewed. The solar corona is filled with highly ionised plasma and magnetic field. Moving charged particles interact with magnetic field due to Lorentz force. This results in gyration motion perpendicular to the magnetic field and free motion along the magnetic field. Circularly polarized electro-magnetic waves interact with gyrating electrons efficiently and the interaction depends on the sense of circular polarization (right-handed or left-handed). This is the reason why we can measure magnetic field strength through microwave observations. This process does not require complicated quantum physics but the classical treatment is enough. Hence the inversion of measured values to magnetic field strength is simpler than in the case of optical and infrared measurements. There are several methods to measure magnetic field strength through microwave observations. We can divide them into two categories: one is based on emission mechanisms and the other is based on wave propagation. In the case of emission mechanisms, thermal f-f emission, thermal gyro-resonance emission and non-thermal gyro-synchrotron emission can be used to measure magnetic field strength. In the case of wave propagation, polarization reversal due to propagation through quasi-transverse magnetic field region can be used. Examples of distribution of magnetic field strength in the solar corona measured by Nobeyama Radioheliograph will be presented.

  20. Microwave power generation by magnetic superlattices

    NASA Astrophysics Data System (ADS)

    Littlejohn, S.; Nogaret, A.; Davies, S. R.; Henini, M.; Beere, H. E.; Ritchie, D. A.

    2011-12-01

    We report on microwave power emission by ballistic electrons as they cross a region of spatially inhomogeneous magnetic field. Magnetic finger gates were fabricated at the surface of high mobility GaAs/AlGaAs Hall bars embedded in a coplanar waveguide. By modulating the current injected through the Hall bar and measuring the second harmonic of the signal rectified by a Schottky detector, we obtain the microwave power emitted by the superlattice. This power (˜6 W m-2) is compared to the fluorescence of electron spins that undergo spin resonance as they cross domains of opposite magnetic field.

  1. Receivers for the Microwave Radiometer on Juno

    NASA Technical Reports Server (NTRS)

    Maiwald, F.; Russell, D.; Dawson, D.; Hatch, W.; Brown, S.; Oswald, J.; Janssen, M.

    2009-01-01

    Six receivers for the MicroWave Radiometer (MWR) are currently under development at JPL. These receivers cover a frequency range of 0.6 to 22 GHz in approximately octave steps, with 4 % bandwidth. For calibration and diagnosis three noise diodes and a Dicke switch are integrated into each receiver. Each receiver is connected to its own antenna which is mounted with its bore sights perpendicular to the spin axis of the spacecraft. As the spacecraft spins at 2 RPM, the antenna field of view scans Jupiter's atmosphere from limb to nadir to limb, measuring microwave emission down to 1000-bar.

  2. Anomalous GPDs in the photon

    E-print Network

    S. Friot; B. Pire; L. Szymanowski

    2007-10-23

    We consider deeply virtual Compton scattering (DVCS) on a photon target, in the generalized Bjorken limit, at the Born order and in the leading logarithmic approximation. This leads us to the extraction of the photon anomalous generalized parton distributions (GPDs) \\cite{url, DVCSphoton}.

  3. Anomalous-viscosity current drive

    DOEpatents

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  4. Cosmological origin of anomalous radio background

    SciTech Connect

    Cline, James M. [Department of Physics, McGill University, 3600 Rue University, Montréal, Québec, H3A 2T8 Canada (Canada); Vincent, Aaron C., E-mail: jcline@physics.mcgill.ca, E-mail: vincent@ific.uv.es [Instituto de Física Corpuscular, Universitat de València - CSIC, 46071, Valencia (Spain)

    2013-02-01

    The ARCADE 2 collaboration has reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum through synchrotron emission. However, constraints from the cosmic microwave background (CMB) anisotropy, on injection of charged particles and on the primordial magnetic field, present a challenge. The simplest scenario is with a ?>9 GeV particle decaying into e{sup +}e{sup ?} at a redshift of z ? 5, in a magnetic field of ? 5?G, which exceeds the CMB B-field constraints, unless the field was generated after decoupling. Decays into exotic millicharged particles can alleviate this tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field.

  5. Quasars with Anomalous H? Profiles. I. Demographics

    NASA Astrophysics Data System (ADS)

    Steinhardt, Charles L.; Silverman, John D.

    2013-08-01

    The H? emission line in a typical Type I quasar is composed of a broad base and a narrow core, with the core velocity characteristic of narrow-line region emission, and line-fitting routines typically assume this picture. We test the effects of removing this constraint, and find a substantial group of Type I quasars in the Sloan Digital Sky Survey catalog with H? emission line cores broader than 1200 km s-1 , above the velocity believed possible for gas in the quasar narrow-line region. We identify this group of ``anomalous H? quasars'' (AHQs) as a distinct population because of a variety of spectral and photometric signatures common to these AHQs but atypical of other quasars. These features are similar to some aspects of narrow-line Seyfert 1s and correlations identified by Eigenvector 1, but also contain distinct features that make it difficult to classify AHQs. We demonstrate that AHQs comprise at least 11% and most likely approximately one quarter of the SDSS Type I quasar population at 0.2 < z < 0.8. For AHQs, the [O III]? 4959, 5007 profile is often better fit by de-linking it from the H? core, while a more standard linked fit produces a tight correlation between narrow- and broad-line velocities. We find that [O III] in AHQs sometimes has a standard narrow-line profile and other times matches the H? core, but is rarely in between the two, implying that the broadened core emission arises from a distinct physical region. Another feature of AHQs is a diminished [O II] line, which might indicate a connection between AHQs and the interstellar mediums of their host galaxies, through reduced photoionization or star formation. We find that it is difficult to produce AHQs using the current quasar standard model.

  6. Considerations for Microwave Remote Sensing of Ocean-Surface Salinity

    Microsoft Academic Search

    Calvin T. Swift; Robert E. Mcintosh

    1983-01-01

    Parametric calculations of the microwave emission from the ocean surface are presented to determine the optimum electromagnetic wavelength for measuring salinity. At 800 MHz, a target accuracy of 240 parts per million is within the state of the art provided that emission due to surface roughness is negligible, or correctable, and that the error resulting from galactic radiation can be

  7. A review of applications of microwave radiometry to oceanography

    Microsoft Academic Search

    Thomas T. Wilheit

    1978-01-01

    The thermal microwave radiation from the ocean surface as seen from space is a function of the surface temperature and wind speed and is modified by liquid water and water vapor in the intervening atmosphere. Further, if the ocean surface is frozen, the emissivity is drastically increased and the effect of the intervening atmosphere is generally negligible. The emissivity of

  8. COBE DMR results and implications. [Differential Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Smoot, George F.

    1992-01-01

    This lecture presents early results obtained from the first six months of measurements of the Cosmic Microwave Background (CMB) by Differential Microwave Radiometers (DMR) aboard COBE and discusses significant cosmological implications. The DMR maps show the dipole anisotropy and some galactic emission but otherwise a spatially smooth early universe. The measurements are sufficiently precise that we must pay careful attention to potential systematic errors. Maps of galactic and local emission such as those produced by the FIRAS and DIRBE instruments will be needed to identify foregrounds from extragalactic emission and thus to interpret the results in terms of events in the early universe. The current DMR results are significant for Cosmology.

  9. Areas of Weakly Anomalous to Anomalous Surface Temperature in Archuleta County, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Archuleta Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Edition: First Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Archuleta County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies). Spatial Domain: Extent: Top: 4144825.235807 m Left: 285446.256851 m Right: 350577.338852 m Bottom: 4096962.250137 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  10. Areas of Weakly Anomalous to Anomalous Surface Temperature in Dolores County, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Dolores Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Dolores County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4186234.213315 m Left: 212558.673056 m Right: 232922.811862 m Bottom: 4176781.467043 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  11. Areas of Weakly Anomalous to Anomalous Surface Temperature in Routt County, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Routt Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Routt County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4501071.574000 m Left: 311351.975000 m Right: 359411.975000 m Bottom: 4447521.574000 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  12. Areas of Weakly Anomalous to Anomalous Surface Temperature in Chaffee County, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Chaffee Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Chaffee County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4333432.368072 m Left: 366907.700763 m Right: 452457.816015 m Bottom: 4208271.566715 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  13. Areas of Weakly Anomalous to Anomalous Surface Temperature in Alamosa and Saguache Counties, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Very Warm Modeled Temperature Alamosa Saguache Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Alamosa and Saguache Counties identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature greater than 2? were considered ASTER modeled very warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4217727.601630 m Left: 394390.400264 m Right: 460179.841813 m Bottom: 4156258.036086 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  14. Areas of Weakly Anomalous to Anomalous Surface Temperature in Garfield County, Colorado, as Identified from ASTER Thermal Data

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Publication Date: 2012 Title: Warm Modeled Temperature Garfield Edition: First Note: This “Weakly Anomalous to Anomalous Surface Temperature” dataset differs from the “Anomalous Surface Temperature” dataset for this county (another remotely sensed CIRES product) by showing areas of modeled temperatures between 1? and 2? above the mean, as opposed to the greater than 2? temperatures contained in the “Anomalous Surface Temperature” dataset. Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science (CIRES), University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains areas of anomalous surface temperature in Garfield County identified from ASTER thermal data and spatial based insolation model. The temperature is calculated using the Emissivity Normalization Algorithm that separate temperature from emissivity. The incoming solar radiation was calculated using spatial based insolation model developed by Fu and Rich (1999). Then the temperature due to solar radiation was calculated using emissivity derived from ASTER data. The residual temperature, i.e. temperature due to solar radiation subtracted from ASTER temperature was used to identify thermally anomalous areas. Areas that had temperature between 1? and 2? were considered ASTER modeled warm surface exposures (thermal anomalies) Spatial Domain: Extent: Top: 4442180.552290 m Left: 268655.053363 m Right: 359915.053363 m Bottom: 4312490.552290 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System ’1984 (WGS ’1984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  15. Microwave Lightcraft concept

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Looking like an alien space ship or a flying saucer the Microwave Lightcraft is an unconventional launch vehicle approach for delivering payload to orbit using power transmitted via microwaves. Microwaves re beamed from either a ground station or an orbiting solar power satellite to the lightcraft. The energy received breaks air molecules into a plasma and a magnetohydrodynamic fanjet provides the lifting force. Only a small amount of propellant is required for circulation, attitude control and deorbit.

  16. Anomalous absorption in a-type asymmetric top molecules in cosmic objects

    NASA Astrophysics Data System (ADS)

    Chandra, Suresh

    Since the detection of the first molecule OH in cosmic objects in 1963, scientists got interested in identification of molecules in the cosmic objects. By now more than 170 molecules have been identified. In order to know about the physical conditions prevailing in the cool cosmic objects and about the chemical reactions going on there, scientists are interested in identification of as many molecules as possible. In some molecular clouds, the kinetic temperature is very low, 10 - 20 K. For such objects, anomalous absorption, i.e., the absorption against the cosmic microwave background, may play an important role for identification of molecules. The transition 111 - 110 at 4.829 GHz of H_2CO was the first one showing the anomalous absorption in the cosmic objects. The molecule H_2CS also has been identified in the cosmic objects. We have discussed about the anomalous absorption of 111 - 110 transition in a-type asymmetric top molecules. For the investigation, the required parameters are the radiative and collisional transition probabilities. We can calculate radiative transition probabilities between the rotational levels. Calculation of collisional rates is a tedious job. In absence of accurate collisional rates, we can investigated the anomalous absorption in a qualitative manner by using the scaled values for collisional rates. We find that anomalous absorption of 111 - 110 transition is possible, provided collisional rates satisfy the required condition.

  17. POLARIMETRIC MICROWAVE RADIOMETER CALIBRATION

    E-print Network

    Ruf, Christopher

    POLARIMETRIC MICROWAVE RADIOMETER CALIBRATION by Jinzheng Peng A dissertation submitted in partial.4 Real Aperture Radiometer ................................................................................... 22 1.6 Radiometer Calibration

  18. Remote sensing of snowpack with microwave radiometers for hydrologic applications

    NASA Technical Reports Server (NTRS)

    Shiue, J. C.; Chang, A. T. C.; Boyne, H.; Ellerbruch, D.

    1978-01-01

    A microwave remote sensing of snowpack experiment is described and some preliminary data presented. A mobile field laboratory consisting of a four-frequency (5, 10.7, 18 and 37 GHz), all with dual linear (vertical and horizontal) polarizations, microwave radiometer system attached to a truck-mounted aerial lift was used to study the microwave emission characteristics of snowpacks in the Colorado Rocky Mountains during the winter of 1977-78. The influence of snowpack physical parameters such as water equivalent, grain size, and melt-freeze cycle on its microwave brightness temperature and its implications to the application of microwave radiometric technique to remote sensing of snowpack for runoff prediction are discussed.

  19. Scientists Detect Radio Emission from Rapidly Rotating Cosmic Dust Grains

    NASA Astrophysics Data System (ADS)

    2001-11-01

    Astronomers have made the first tentative observations of a long-speculated, but never before detected, source of natural radio waves in interstellar space. Data from the National Science Foundation's 140 Foot Radio Telescope at the National Radio Astronomy Observatory in Green Bank, W.Va., show the faint, tell-tale signals of what appear to be dust grains spinning billions of times each second. This discovery eventually could yield a powerful new tool for understanding the interstellar medium - the immense clouds of gas and dust that populate interstellar space. The NRAO 140 Foot Radio Telescope The NRAO 140-Foot Radio Telescope "What we believe we have found," said Douglas P. Finkbeiner of Princeton University's Department of Astrophysics, "is the first hard evidence for electric dipole emission from rapidly rotating dust grains. If our studies are confirmed, it will be the first new source of continuum emission to be conclusively identified in the interstellar medium in nearly the past 20 years." Finkbeiner believes that these emissions have the potential in the future of revealing new and exciting information about the interstellar medium; they also may help to refine future studies of the Cosmic Microwave Background Radiation. The results from this study, which took place in spring 1999, were accepted for publication in Astrophysical Journal. Other contributors to this paper include David J. Schlegel, department of astrophysics, Princeton University; Curtis Frank, department of astronomy, University of Maryland; and Carl Heiles, department of astronomy, University of California at Berkeley. "The idea of dust grains emitting radiation by rotating is not new," comments Finkbeiner, "but to date it has been somewhat speculative." Scientists first proposed in 1957 that dust grains could emit radio signals, if they were caused to rotate rapidly enough. It was believed, however, that these radio emissions would be negligibly small - too weak to be of any impact to current radio astronomy research, and the idea was largely forgotten. In the 1990s this perception began to change when scientists and engineers designed sensitive instruments to detect the faint afterglow of the Big Bang, which is seen in the Universe as the Cosmic Microwave Background Radiation. While making detailed maps of this faint and cold radiation, scientists also detected signals at approximately the same wavelength and intensity as the background radiation, but clearly emanating from within the Milky Way's galactic plane. The researchers expected to detect some emission from the Milky Way, but what they encountered was much brighter than anticipated. This discovery caused some concern among researchers because of the need to have a very clear "window" on the Universe to study the background radiation in great detail. If there were a source of radio emission in our own galactic "back yard," then studies of the microwave background radiation would need to recognize these emissions and correct for them. "We want to be clear, however, that nothing we have found invalidates the current interpretation of the Cosmic Microwave Background Radiation," assured Finkbeiner. "Nobody has done anything wrong in neglecting these signals - so far." Scientists considered several plausible mechanisms for this anomalous emission, but these theories failed to explain the observed spatial distribution of this emission across the sky. This predicament prompted theorists to rethink the spinning dust idea, leading to a 1998 model by Bruce Draine (Princeton University) and Alex Lazarian (University of Wisconsin), which proposed rotational dust-grain emission as an important mechanism. Draine and Lazarian assumed that small dust grains, perhaps having no more than 100 atoms each, would populate many interstellar dust clouds in the Galaxy. Each grain would have a small electric dipole and would therefore react to the charged ions that race through the clouds at tremendous speeds. As an ion either strik

  20. No evidence for anomalously low variance circles on the sky

    SciTech Connect

    Moss, Adam; Scott, Douglas; Zibin, James P., E-mail: adammoss@phas.ubc.ca, E-mail: dscott@phas.ubc.ca, E-mail: zibin@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver (Canada)

    2011-04-01

    In a recent paper, Gurzadyan and Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the very early Universe. We attempted to repeat the analysis of these authors, and we can indeed confirm that such variations do exist in the temperature variance for annuli around points in the data. However, we find that this variation is entirely expected in a sky which contains the usual CMB anisotropies. In other words, properly simulated Gaussian CMB data contain just the sorts of variations claimed. Gurzadyan and Penrose have not found evidence for pre-Big Bang phenomena, but have simply re-discovered that the CMB contains structure.

  1. Anomalous sounds from the entry of meteor fireballs.

    PubMed

    Keay, C S

    1980-10-01

    A very bright fireball observed over New South Wales in 1978 produced anomalous sounds clearly audible to some of the observers. An investigation of the phenomenon indicates that bright fireballs radiate considerable electromagnetic energy in the very-low-frequency (VLF) region of the spectrum. A mechanism for the production of VLF emissions from the highly energetic wake turbulence of the fireball is proposed. Trials with human subjects revealed a very extended range of thresholds for the perception of electrically excited sounds among a sample population, particularly when the VLF electric field excites surface acoustic waves in surrounding objects. This fact, together with variable propagation effects and local conditions, can account for the sporadic distribution of reports of anomalous sounds from fireballs and auroras. PMID:17751127

  2. Causes of anomalous line-splitting in RV Tauri stars

    NASA Astrophysics Data System (ADS)

    Baird, S. R.

    1984-01-01

    Data on the anomalous absorption-line splitting and emission in the RV Tauri stars AC Her, U Mon, and R Sct are examined. It is shown that the Karp line-splitting mechanism for cepheids cannot explain the highly redshifted lines that appear without antecedents in some RV Tauri stars and that the veiling that occurs during rising light appears to affect the bluer absorption components more than the high redshift ones. Evidence is reviewed showing strong shock waves must be present in RV Tauri star atmospheres, and a two-shock picture to explain the anomalous line splitting is presented based on a model for long-period variables by Hill and Willson. Advantages and difficulties of the model are discussed.

  3. Effects of Microwave Radiation on Oil Recovery

    NASA Astrophysics Data System (ADS)

    Esmaeili, Abdollah

    2011-12-01

    A variety of oil recovery methods have been developed and applied to mature and depleted reservoirs in order to improve the efficiency. Microwave radiation oil recovery method is a relatively new method and has been of great interest in the recent years. Crude oil is typically co-mingled with suspended solids and water. To increase oil recovery, it is necessary to remove these components. The separation of oil from water and solids using gravitational settling methods is typically incomplete. Oil-in-water and oil-water-solid emulsions can be demulsified and separated into their individual layers by microwave radiation. The data also show that microwave separation is faster than gravity separation and can be faster than conventional heating at many conditions. After separation of emulsion into water and oil layers, water can be discharged and oil is collected. High-frequency microwave recycling process can recover oil and gases from oil shale, residual oil, drill cuttings, tar sands oil, contaminated dredge/sediments, tires and plastics with significantly greater yields and lower costs than are available utilizing existing known technologies. This process is environmentally friendly, fuel-generating recycler to reduce waste, cut emissions, and save energy. This paper presents a critical review of Microwave radiation method for oil recovery.

  4. Magnetic effects in anomalous dispersion

    SciTech Connect

    Blume, M.

    1992-12-31

    Spectacular enhancements of magnetic x-ray scattering have been predicted and observed experimentally. These effects are the result of resonant phenomena closely related to anomalous dispersion, and they are strongest at near-edge resonances. The theory of these resonances will be developed with particular attention to the symmetry properties of the scatterer. While the phenomena to be discussed concern magnetic properties the transitions are electric dipole or electric quadrupole in character and represent a subset of the usual anomalous dispersion phenomena. The polarization dependence of the scattering is also considered, and the polarization dependence for magnetic effects is related to that for charge scattering and to Templeton type anisotropic polarization phenomena. It has been found that the strongest effects occur in rare-earths and in actinides for M shell edges. In addition to the scattering properties the theory is applicable to ``forward scattering`` properties such as the Faraday effect and circular dichroism.

  5. Minimal muon anomalous magnetic moment

    NASA Astrophysics Data System (ADS)

    Biggio, Carla; Bordone, Marzia

    2015-02-01

    We classify all possible one-particle (scalar and fermion) extensions of the Standard Model that can contribute to the anomalous magnetic moment of leptons. We review the cases already discussed in the literature and complete the picture by performing the calculation for a fermionic doublet with hypercharge -3/2. We conclude that, out of the listed possibilities, only two scalar leptoquarks and the pseudoscalar of a peculiar two-Higgs-doublet model could be the responsibles for the muon anomalous magnetic moment discrepancy. Were this the case, this particles could be seen in the next LHC run. To this aim, especially to test the leptoquark hypothesis, we suggest to look for final states with tops and muons.

  6. Satellite microwave observations of the Utah Great Salt Lake Desert

    Microsoft Academic Search

    Fawwaz T. Ulaby; Louis F. Dellwig; Thomas Schmugge

    1975-01-01

    Microwave data acquired over the Great Salt Lake Desert area by sensors aboard Skylab and Nimbus 5 indicate that the microwave emission and backscatter were strongly influenced by contributions from subsurface layers of sediment saturated with brine. This phenomenon was observed by Skylab's S-194 radiometer operating at 1.4 GHz, S-193 RADSCAT (Radiometer-Scatterometer) operating at 13.9 GHz, and the Nimbus 5

  7. Horizon universality and anomalous conductivities

    E-print Network

    Umut Gursoy; Javier Tarrio

    2014-10-06

    We show that the value of chiral conductivities associated with anomalous transport is universal in a general class of strongly coupled quantum field theories. Our result applies to theories with no dynamical gluon fields and admitting a gravitational holographic dual in the large N limit. On the gravity side the result follows from near horizon universality of the fluctuation equations, similar to the holographic calculation of the shear viscosity.

  8. Anomalous thermodynamic behavior in actinides

    NASA Astrophysics Data System (ADS)

    Shekhter, Arkady

    2013-03-01

    The thermal expansion of some of the actinides metals are strongly dependent upon doping. Extreme examples involve a change of sign of the thermal expansion coefficient upon few percent Ga doping. In contrast, resonant ultrasound spectroscopy of these doping series reveals very weak dependence of the elastic moduli on Ga content. We suggest that the anomalous thermodynamic behavior in these systems has dynamic rather than static origin.

  9. Anomalous Transport Effects in Auroras

    NASA Astrophysics Data System (ADS)

    Jasperse, J. R.; Basu, B.; Lund, E. J.; Grossbard, N.

    2011-12-01

    The physical processes that determine the fluid quantities and the self-consistent, electric field (Epar) parallel to the magnetic field have been an unresolved problem in magnetospheric physics for over forty years. Recently, we have published a new kinetic and multimoment fluid theory for inhomogeneous, nonuniformly magnetized plasma with temperature anisotropy and applied the theory to solve for the quasi steady state in the long-range potential region of a downward Birkeland current sheet when electrostatic ion cyclotron turbulence was dominant. See Jasperse et al. [2006a, 2006b, 2010a, 2010b, and 2011]. We find that the turbulence produces an enhancement in the magnitude of Epar by nearly a factor of forty compared to the case when it is absent. Anomalous momentum transfer (anomalous resistivity) by itself has a very small effect on Epar; however, the presence of the turbulence and the anomalous energy transfers (anomalous heating and cooling) that result have a very large effect on the entire solution. In the electron and ion momentum-balance equations for Epar, the turbulence enhances the magnitude of Epar by reducing the effect of the generalized parallel pressure gradients and thereby enhancing the effect of the mirror forces. A new, nonlinear formula for the current-voltage relation in downward current regions is also given which is different from the Knight relation for upward currents. Jasperse et al., Phys. Plasmas 13, 072903 [2006a], Phys. Plasmas 13, 112902 [2006b], Phys. Plasmas 17, 062903 [2010a], Phys. Plasmas 17, 062904 [2010b], and J. Geophys. Res., in press [2011].

  10. Satellite microwave observations of the Utah Great Salt Lake Desert

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dellwig, L. F.; Schmugge, T.

    1975-01-01

    Microwave data acquired over the Great Salt Lake Desert area by sensors aboard Skylab and Nimbus 5 indicate that the microwave emission and backscatter were strongly influenced by contributions from subsurface layers of sediment saturated with brine. This phenomenon was observed by Skylab's S-194 radiometer operating at 1.4 GHz, S-193 RADSCAT (Radiometer-Scatterometer) operating at 13.9 GHz, and the Nimbus 5 ESMR (Electrically Scanning Microwave Radiometer) operating at 19.35 GHz. The availability of ESMR data over an 18-month period allowed an investigation of temporal variations.

  11. Correlation between galactic HI and the cosmic microwave background

    SciTech Connect

    Land, Kate [Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, OX3RH1, Oxford (United Kingdom); Slosar, Anze [Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, OX3RH1, Oxford (United Kingdom); Faculty of Mathematics and Physics, University of Ljubljana (Slovenia)

    2007-10-15

    We revisit the issue of a correlation between the atomic hydrogen gas in our local galaxy and the cosmic microwave background, a detection of which has been claimed in some literature. We cross correlate the 21-cm emission of galactic atomic hydrogen as traced by the Leiden/Argentine/Bonn Galactic Hi survey with the 3-year cosmic microwave background data from the Wilkinson microwave anisotropy probe. We consider a number of angular scales, masks, and Hi velocity slices and find no statistically significant correlation.

  12. Variable frequency microwave heating apparatus

    DOEpatents

    Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN); Johnson, Arvid C. (Lake in the Hills, IL); Thigpen, Larry T. (Angier, NC)

    1999-01-01

    A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

  13. MICROWAVES IN ORGANIC SYNTHESIS

    EPA Science Inventory

    The effect of microwaves, a non-ionizing radiation, on organic reactions is described both in polar solvents and under solvent-free conditions. The special applications are highlighted in the context of solventless organic synthesis which involve microwave (MW) exposure of neat r...

  14. The Cosmic Microwave Background

    E-print Network

    Arthur Kosowsky

    2001-02-23

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  15. Microwave hydrology: A trilogy

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.; Johnston, E. J.; Girard, M. A.; Regusters, H. A.

    1985-01-01

    Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest.

  16. Microwave ion source

    DOEpatents

    Leung, Ka-Ngo; Reijonen, Jani; Thomae, Rainer W.

    2005-07-26

    A compact microwave ion source has a permanent magnet dipole field, a microwave launcher, and an extractor parallel to the source axis. The dipole field is in the form of a ring. The microwaves are launched from the middle of the dipole ring using a coaxial waveguide. Electrons are heated using ECR in the magnetic field. The ions are extracted from the side of the source from the middle of the dipole perpendicular to the source axis. The plasma density can be increased by boosting the microwave ion source by the addition of an RF antenna. Higher charge states can be achieved by increasing the microwave frequency. A xenon source with a magnetic pinch can be used to produce intense EUV radiation.

  17. Detection of solar coronal magnetic loop oscillations in microwaves

    NASA Astrophysics Data System (ADS)

    Khodachenko, M. L.; Kislyakov, A. G.; Rucker, H. O.; Zaitsev, V. V.; Urpo, S.

    Analysis of the Low-Frequency fluctuations of solar microwave radiation 37 GHz and 11 7 GHz appears as a relatively new direction of investigations in the traditional branch of the microwave radio astronomy For this purpose a sliding window Fourier transform combined with the Wigner-Ville technique is applied It has been shown that slow variations of the electric current and associated magnetic field in a source of solar microwave emission as well as a large-scale motion of the source can modulate the intensity of the received signal Special attention in the present study is paid to the analysis of modulations of microwave emission recorded at the same time when TRACE EUV telescope observed large scale oscillations of coronal loops For some events the spatial resolution of the radio telescope at 37 GHz allows also to localize an active region containing the oscillating loops The applied data analysis technique besides of the modulations probably connected with loop oscillations detected by TRACE makes possible to detect additional modulations which may be associated with oscillations of smaller invisible for TRACE loops These modulations can be connected as well with specific wave modes sausage mode excited in solar coronal structures Comparative analysis of phases of oscillations of TRACE loops and the microwave emission modulation allows deeper insight into the global dynamics and structure of solar active regions This makes the analysis of LF modulations of microwave radiation intensity to be an important and useful tool for

  18. 23. Cosmic microwave background 1 23. COSMIC MICROWAVE BACKGROUND

    E-print Network

    23. Cosmic microwave background 1 23. COSMIC MICROWAVE BACKGROUND Revised August 2009 by D. Scott from beyond our Galaxy is dominated by the Cosmic Microwave Background (CMB), discovered in 1965 [1;2 23. Cosmic microwave background 23.2.1. The Monopole : The CMB has a mean temperature of T = 2

  19. 25. Cosmic microwave background 1 25. COSMIC MICROWAVE BACKGROUND

    E-print Network

    25. Cosmic microwave background 1 25. COSMIC MICROWAVE BACKGROUND Revised August 2011 by D. Scott from beyond our Galaxy is dominated by the cosmic microwave background (CMB), discovered in 1965 [1://pdg.lbl.gov) June 18, 2012 16:19 #12;2 25. Cosmic microwave background 25.2.1. The Monopole : The CMB has a mean

  20. 23. Cosmic microwave background 1 23. COSMIC MICROWAVE BACKGROUND

    E-print Network

    23. Cosmic microwave background 1 23. COSMIC MICROWAVE BACKGROUND Revised August 2011 by D. Scott from beyond our Galaxy is dominated by the cosmic microwave background (CMB), discovered in 1965 [1 update for the 2012 edition (pdg.lbl.gov) February 16, 2012 14:07 #12;2 23. Cosmic microwave background

  1. Harmonic In-painting of Cosmic Microwave Background Sky by Constrained Gaussian Realization

    NASA Astrophysics Data System (ADS)

    Kim, Jaiseung; Naselsky, Pavel; Mandolesi, Nazzareno

    2012-05-01

    The presence of astrophysical emissions between the last scattering surface and our vantage point requires us to apply a foreground mask on cosmic microwave background (CMB) sky maps, leading to large cuts around the Galactic equator and numerous holes. Since many CMB analysis, in particular on the largest angular scales, may be performed on a whole-sky map in a more straightforward and reliable manner, it is of utmost importance to develop an efficient method to fill in the masked pixels in a way compliant with the expected statistical properties and the unmasked pixels. In this Letter, we consider the Monte Carlo simulation of a constrained Gaussian field and derive it CMB anisotropy in harmonic space, where a feasible implementation is possible with good approximation. We applied our method to simulated data, which shows that our method produces a plausible whole-sky map, given the unmasked pixels, and a theoretical expectation. Subsequently, we applied our method to the Wilkinson Microwave Anisotropy Probe foreground-reduced maps and investigated the anomalous alignment between quadrupole and octupole components. From our investigation, we find that the alignment in the foreground-reduced maps is even higher than the Internal Linear Combination map. We also find that the V-band map has higher alignment than other bands, despite the expectation that the V-band map has less foreground contamination than other bands. Therefore, we find it hard to attribute the alignment to residual foregrounds. Our method will be complementary to other efforts on in-painting or reconstructing the masked CMB data, and of great use to Planck surveyor and future missions.

  2. HARMONIC IN-PAINTING OF COSMIC MICROWAVE BACKGROUND SKY BY CONSTRAINED GAUSSIAN REALIZATION

    SciTech Connect

    Kim, Jaiseung; Naselsky, Pavel [Niels Bohr Institute and Discovery Center, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Mandolesi, Nazzareno, E-mail: jkim@nbi.dk [INAF/IASF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, Istituto Nazionale di Astrofisica, via Gobetti 101, I-40129 Bologna (Italy)

    2012-05-01

    The presence of astrophysical emissions between the last scattering surface and our vantage point requires us to apply a foreground mask on cosmic microwave background (CMB) sky maps, leading to large cuts around the Galactic equator and numerous holes. Since many CMB analysis, in particular on the largest angular scales, may be performed on a whole-sky map in a more straightforward and reliable manner, it is of utmost importance to develop an efficient method to fill in the masked pixels in a way compliant with the expected statistical properties and the unmasked pixels. In this Letter, we consider the Monte Carlo simulation of a constrained Gaussian field and derive it CMB anisotropy in harmonic space, where a feasible implementation is possible with good approximation. We applied our method to simulated data, which shows that our method produces a plausible whole-sky map, given the unmasked pixels, and a theoretical expectation. Subsequently, we applied our method to the Wilkinson Microwave Anisotropy Probe foreground-reduced maps and investigated the anomalous alignment between quadrupole and octupole components. From our investigation, we find that the alignment in the foreground-reduced maps is even higher than the Internal Linear Combination map. We also find that the V-band map has higher alignment than other bands, despite the expectation that the V-band map has less foreground contamination than other bands. Therefore, we find it hard to attribute the alignment to residual foregrounds. Our method will be complementary to other efforts on in-painting or reconstructing the masked CMB data, and of great use to Planck surveyor and future missions.

  3. Photonic technology for microwave engineering

    Microsoft Academic Search

    BOGDAN A. GALWAS

    1998-01-01

    The paper presents a review of photonic devices and technology applications in microwave systems. Four fundamental applications are discussed: transmission of microwave signals by optical links, use of photonic devices for generation and controlling of microwave signals, principles of operation of phase-arrayed antennas with photonic transmission, and finally, microwave measurements methods with photonic techniques

  4. Has the Photon an Anomalous Magnetic Moment?

    E-print Network

    S. Villalba-Chávez; H. Pérez-Rojas

    2006-09-01

    Due to its interaction with the virtual electron-positron field in vacuum, the photon exhibits a nonzero anomalous magnetic moment whenever it has a nonzero transverse momentum component to an external constant magnetic field. At low and high frequencies this anomalous magnetic moment behaves as paramagnetic, and at energies near the first threshold of pair creation it has a maximum value greater than twice the electron anomalous magnetic moment. These results might be interesting in an astrophysical and cosmological context.

  5. Microwave vision for robots

    NASA Technical Reports Server (NTRS)

    Lewandowski, Leon; Struckman, Keith

    1994-01-01

    Microwave Vision (MV), a concept originally developed in 1985, could play a significant role in the solution to robotic vision problems. Originally our Microwave Vision concept was based on a pattern matching approach employing computer based stored replica correlation processing. Artificial Neural Network (ANN) processor technology offers an attractive alternative to the correlation processing approach, namely the ability to learn and to adapt to changing environments. This paper describes the Microwave Vision concept, some initial ANN-MV experiments, and the design of an ANN-MV system that has led to a second patent disclosure in the robotic vision field.

  6. Microwave coupler and method

    DOEpatents

    Holcombe, C.E.

    1984-11-29

    The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

  7. Microwave coupler and method

    DOEpatents

    Holcombe, Cressie E. (Farragut, TN)

    1985-01-01

    The present invention is directed to a microwave coupler for enhancing the heating or metallurgical treatment of materials within a cold-wall, rapidly heated cavity as provided by a microwave furnace. The coupling material of the present invention is an alpha-rhombohedral-boron-derivative-structure material such as boron carbide or boron silicide which can be appropriately positioned as a susceptor within the furnace to heat other material or be in powder particulate form so that composites and structures of boron carbide such as cutting tools, grinding wheels and the like can be rapidly and efficiently formed within microwave furnaces.

  8. Microwave thawing apparatus and method

    DOEpatents

    Fathi, Zakaryae; Lauf, Robert J.; McMillan, April D.

    2004-06-01

    An apparatus for thawing a frozen material includes: a microwave energy source; a microwave applicator which defines a cavity for applying microwave energy from the microwave source to a material to be thawed; and a shielded region which is shielded from the microwave source, the shielded region in fluid communication with the cavity so that thawed material may flow from the cavity into the shielded region.

  9. Lagrangian turbulence and anomalous transport

    NASA Astrophysics Data System (ADS)

    Zaslavskii, G. M.

    1991-10-01

    The motion of a passive particle in a given velocity field can be considered from the viewpoint of dynamic systems theory. A two-dimensional time-dependent field and a three-dimensional field generate chaotic behavior of liquid particles. The diffusion process of liquid particles is considered as a random walk process in the fractal space and time. This leads to anomalous transport properties of the particles. The notion of stochastic jets is introduced. A complete analysis is given for a special form of Beltrami flows - so-called Q-flows with symmetry of the order of Q.

  10. Galilean satellites - Anomalous temperatures disputed

    NASA Technical Reports Server (NTRS)

    Morrison, D.; Lebofsky, L. A.; Veeder, G. J.; Cutts, J. A.

    1977-01-01

    Anomalous averaged infrared brightness temperatures of the Galilean satellites of Jupiter reported by Gross (1975) are rejected as falsely conceived and lacking physical reality. It is argued that the calculations of equilibrium temperatures should be corrected, whereupon predictions would be in satisfactory agreement with observations, in conformity with the radiometric method of determining the diameters of asteroids and satellites. The IR irradiance and the related disk-averaged brightness temperature for the spectral band are recommended as more relevant. Attention is drawn to some interesting discrepancies between calculated and observed temperatures of the Jovian satellites which merit further investigation.

  11. Anomalous Transport from Kubo Formulae

    NASA Astrophysics Data System (ADS)

    Landsteiner, Karl; Megías, Eugenio; Peña-Benitez, Francisco

    Chiral anomalies have profound impact on the transport properties of relativistic fluids. In four dimensions there are different types of anomalies, pure gauge and mixed gauge-gravitational anomalies. They give rise to two new non-dissipative transport coefficients, the chiral magnetic conductivity and the chiral vortical conductivity. They can be calculated from the microscopic degrees of freedom with the help of Kubo formulae. We review the calculation of the anomalous transport coefficients via Kubo formulae with a particular emphasis on the contribution of the mixed gauge-gravitational anomaly.

  12. Anomalous Transport from Kubo Formulae

    E-print Network

    Karl Landsteiner; Eugenio Megias; Francisco Pena-Benitez

    2012-08-08

    Chiral anomalies have profound impact on the transport properties of relativistic fluids. In four dimensions there are different types of anomalies, pure gauge and mixed gauge-gravitational anomalies. They give rise to two new non-dissipative transport coefficients, the chiral magnetic conductivity and the chiral vortical conductivity. They can be calculated from the microscopic degrees of freedom with the help of Kubo formulae. We review the calculation of the anomalous transport coefficients via Kubo formulae with a particular emphasis on the contribution of the mixed gauge-gravitational anomaly.

  13. Anomalous Transport from Kubo Formulae

    E-print Network

    Landsteiner, Karl; Pena-Benitez, Francisco

    2012-01-01

    Chiral anomalies have profound impact on the transport properties of relativistic fluids. In four dimensions there are different types of anomalies, pure gauge and mixed gauge-gravitational anomalies. They give rise to two new non-dissipative transport coefficients, the chiral magnetic conductivity and the chiral vortical conductivity. They can be calculated from the microscopic degrees of freedom with the help of Kubo formulae. We review the calculation of the anomalous transport coefficients via Kubo formulae with a particular emphasis on the contribution of the mixed gauge-gravitational anomaly.

  14. The small scale power asymmetry in the cosmic microwave background

    SciTech Connect

    Flender, Samuel; Hotchkiss, Shaun, E-mail: samuel.flender@helsinki.fi, E-mail: shaun.hotchkiss@helsinki.fi [Department of Physics, University of Helsinki and Helsinki Institute of Physics, P.O. Box 64, FIN-00014, University of Helsinki (Finland)

    2013-09-01

    We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l = 601?2048, with a naive statistical significance of 6.5?. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations. After correcting for all of these effects, the significance level drops to ? 1?, i.e., there is no anomalous intrinsic asymmetry in the small angular scales. Using this null result, we derive a constraint on a potential dipolar modulation amplitude, A(k) < 0.0045 on the ? 10 Mpc-scale, at 95% C.L. This new constraint must be satisfied by any theoretical model attempting to explain the hemispherical asymmetry at large angular scales.

  15. The small scale power asymmetry in the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Flender, Samuel; Hotchkiss, Shaun

    2013-09-01

    We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l = 601-2048, with a naive statistical significance of 6.5?. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations. After correcting for all of these effects, the significance level drops to ~ 1?, i.e., there is no anomalous intrinsic asymmetry in the small angular scales. Using this null result, we derive a constraint on a potential dipolar modulation amplitude, A(k) < 0.0045 on the ~ 10 Mpc-scale, at 95% C.L. This new constraint must be satisfied by any theoretical model attempting to explain the hemispherical asymmetry at large angular scales.

  16. New microwave spectrometer/imager has possible applications for pollution monitoring

    NASA Technical Reports Server (NTRS)

    Tooley, R. D.

    1970-01-01

    Microwave imager forms thermal-emissivity image of solid portion of planet Venus and provides data on the planet's atmosphere, surface, terminator, and temperature changes. These thermally produced multifrequency microwaves for image production of temperature profiles can be applied to water pollution monitoring, agriculture, and forestry survey.

  17. Attempted Microwave Measurement of Temperature of a Shock-Heated Plasma

    Microsoft Academic Search

    T. O. Aro; D. Walsh

    1967-01-01

    Microwave noise radiation offers a simple probeless way of measuring the electron temperature of a hot plasma. The main difficulty usually lies in giving a true value to the emissivity. The temperature of the equilibrium region behind shocks in argon has been determined from the measurement of the microwave noise emitted by the shock-ionized argon in a shock tube and

  18. Elemental analysis by microwave-assisted laser-induced breakdown spectroscopy: Evaluation on ceramics

    E-print Network

    Richardson, Martin C.

    -frequency plasma, microwave plasma, glow discharges, laser-induced plasma.1,3 Laser-induced plasma emission spec the laser intensity onto the sample and create a plasma, collection optics (free space or fiberElemental analysis by microwave-assisted laser-induced breakdown spectroscopy: Evaluation

  19. Remote Microwave Plasma Enhanced Chemical Vapour Deposition of SiO 2 Films : Oxygen Plasma Diagnostic

    Microsoft Academic Search

    C. Regnier; J. Desmaison; P. Tristant; D. Merle

    1995-01-01

    Silicon oxide is deposited by remote microwave plasma enhanced chemical vapour deposition (RMPECVD). The silica films are produced by exciting oxygen in a microwave discharge while a mixture of 5% of silane diluted in argon is introduced downstream. In the afterglow, double Langmuir probe measurements and rotational temperatures deduced from optical emission spectroscopy (OES), show that the electron energy is

  20. Microwave Radiation Detector

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1984-01-01

    Direct photon detector responds to microwave frequencies. Method based on trapped-ion frequency-generation standards proposed to detect radio-frequency (RF) radiation at 40.5 GHz. Technique used for directdetection (RF) communication, radar, and radio astronomy.

  1. Emitron: microwave diode

    DOEpatents

    Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

    1982-05-06

    The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

  2. The Cosmic Microwave Background

    E-print Network

    Joseph Silk

    2002-12-12

    I review the discovery of the temperature fluctuations in the cosmic microwave background radiation. The underlying theory and the implications for cosmology are reviewed, and I describe the prospects for future progress.

  3. Microwave beam power

    NASA Technical Reports Server (NTRS)

    Faymon, Karl A.

    1989-01-01

    Information on microwave beam power is given in viewgraph form. Information is given on orbit transfer proulsion applications, costs of delivering 100 kWe of usable power, and costs of delivering a 1 kg payload into orbit.

  4. Microwave sensing from orbit

    NASA Technical Reports Server (NTRS)

    Kritikos, H. N.; Shiue, J.

    1979-01-01

    Microwave sensors, used in conjunction with the traditional sensors of visible and infrared light to extend present capabilities of global weather forecasts and local storm watches, are discussed. The great advantage of these sensors is that they can penetrate or 'see' through cloud formations to monitor temperature, humidity and wind fields below the clouds. Other uses are that they can penetrate the earth deeper than optical and IR systems; they can control their own angle of incidence; they can detect oil spills; and they can enhance the studies of the upper atmosphere through measurement of temperature, water vapor and other gaseous species. Two types of microwave sensors, active and passive, are examined. Special attention is given to the study of the microwave radiometer and the corresponding temperature resolution as detected by the antenna. It is determined that not only will the microwave remote sensors save lives by allowing close monitoring of developing storms, but also save approximately $172 million/year.

  5. New microwave coupler material

    Microsoft Academic Search

    Holcombe

    1983-01-01

    The unexpected coupling of urania (UO\\/sub x\\/, with 2 less than or equal to x less than or equal to 3) to microwave energy has previously been reported. The present study screened several different materials for coupling with microwave energy using a 1.6 kW, 2450 MHz system. Materials were nominally -100 mesh powder, >99% pure. Those which showed minimal or

  6. Kinetic studies of anomalous transport

    SciTech Connect

    Tang, W.M.

    1990-11-01

    Progress in achieving a physics-based understanding of anomalous transport in toroidal systems has come in large part from investigations based on the proposition that low frequency electrostatic microinstabilities are dominant in the bulk ( confinement'') region of these plasmas. Although the presence here of drift-type modes dependent on trapped particle and ion temperature gradient driven effects appears to be consistent with a number of important observed confinement trends, conventional estimates for these instabilities cannot account for the strong current (I{sub p}) and /or q-scaling frequently found in empirically deduced global energy confinement times for auxiliary-heated discharges. The present paper deals with both linear and nonlinear physics features, ignored in simpler estimates, which could introduce an appreciable local dependence on current. It is also pointed out that while the thermal flux characteristics of drift modes have justifiably been the focus of experimental studies assessing their relevance, other transport properties associated with these microinstabilities should additionally be examined. Accordingly, the present paper provides estimates and discusses the significance of anomalous energy exchange between ions and electrons when fluctuations are present. 19 refs., 3 figs.

  7. Gain-assisted superluminal microwave pulse propagation via four-wave mixing in superconducting phase quantum circuits

    E-print Network

    Sabegh, Z Amini; Maleki, M A; Mahmoudi, M

    2015-01-01

    We study the propagation and amplification of a microwave field in a four-level cascade quantum system which is realized in a superconducting phase quantum circuit. It is shown that by increasing the microwave pump tones feeding the system, the normal dispersion switches to the anomalous and the gain-assisted superluminal microwave propagation is obtained in this system. Moreover, it is demonstrated that the stimulated microwave field is generated via four-wave mixing without any inversion population in the energy levels of the system (amplification without inversion) and the group velocity of the generated pulse can be controlled by the external oscillating magnetic fluxes. We also show that in some special set of parameters, the absorption-free superluminal generated microwave propagation is obtained in superconducting phase quantum circuit system.

  8. Optical diagnostics of a low power---low gas flow rates atmospheric-pressure argon plasma created by a microwave plasma torch

    Microsoft Academic Search

    Chuji Wang; Nimisha Srivastava; Susan Scherrer; Ping-Rey Jang; Theodore S. Dibble; Yixiang Duan

    2009-01-01

    We employ a suite of optical techniques, namely, visual imaging, optical emission spectroscopy and cavity ringdown spectroscopy (CRDS), to characterize a low power, low gas flow rates, atmospheric-pressure argon microwave induced plasma. The plasma is created by a microwave plasma torch, which is excited by a 2.45 GHz microwave with powers ranging from 60 to 120 W. A series of

  9. Microwave Quantum Illumination

    NASA Astrophysics Data System (ADS)

    Barzanjeh, Shabir; Guha, Saikat; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H.; Pirandola, Stefano

    2015-02-01

    Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here, we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy.

  10. Microwave quantum illumination.

    PubMed

    Barzanjeh, Shabir; Guha, Saikat; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

    2015-02-27

    Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here, we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy. PMID:25768743

  11. Anomalous magnetoconductance beyond the diffusion limit

    Microsoft Academic Search

    Hans-Peter Wittmann; Albert Schmid

    1987-01-01

    The weak localization contribution to the conductance depends sensitively on the applied magnetic field. This anomalous magnetoconductance provides a unique tool for the identification of weak localization and other phenomena associated with it. The standard theory of the anomalous magnetoconductance is based on the diffusion approximation, which applies to the case where the number of elastic scattering events is very

  12. Dressed-quark anomalous magnetic moments

    E-print Network

    Lei Chang; Yu-Xin Liu; Craig D. Roberts

    2010-09-17

    Perturbation theory predicts that a massless fermion cannot possess a measurable magnetic moment. We explain, however, that the nonperturbative phenomenon of dynamical chiral symmetry breaking generates a momentum-dependent anomalous chromomagnetic moment for dressed light-quarks, which is large at infrared momenta; and demonstrate that consequently these same quarks also possess an anomalous electromagnetic moment with similar magnitude and opposite sign.

  13. Wanted: A Positive Control for Anomalous Subdiffusion

    PubMed Central

    Saxton, Michael J.

    2012-01-01

    Anomalous subdiffusion in cells and model systems is an active area of research. The main questions are whether diffusion is anomalous or normal, and if it is anomalous, its mechanism. The subject is controversial, especially the hypothesis that crowding causes anomalous subdiffusion. Anomalous subdiffusion measurements would be strengthened by an experimental standard, particularly one able to cross-calibrate the different types of measurements. Criteria for a calibration standard are proposed. First, diffusion must be anomalous over the length and timescales of the different measurements. The length-scale is fundamental; the time scale can be adjusted through the viscosity of the medium. Second, the standard must be theoretically well understood, with a known anomalous subdiffusion exponent, ideally readily tunable. Third, the standard must be simple, reproducible, and independently characterizable (by, for example, electron microscopy for nanostructures). Candidate experimental standards are evaluated, including obstructed lipid bilayers; aqueous systems obstructed by nanopillars; a continuum percolation system in which a prescribed fraction of randomly chosen obstacles in a regular array is ablated; single-file diffusion in pores; transient anomalous subdiffusion due to binding of particles in arrays such as transcription factors in randomized DNA arrays; and computer-generated physical trajectories. PMID:23260043

  14. ANOMALOUS BEHAVIOUR OF MOLYBDENUM IN STEEL WELDS

    E-print Network

    Cambridge, University of

    ANOMALOUS BEHAVIOUR OF MOLYBDENUM IN STEEL WELDS Habib Ullah Choudhary Churchill College Cambridge of molybdenum to steel welds in quite small concentrations leads to a variety of anomalous microstructural. A quantitative analysis of molybdenum-containing steel welds indi- cates that there is a degree of strengthening

  15. JOURiVAL DE PHYSIQUE CoZZoque C7, suppZ6ment atr n07, Tome 40, JuiZZet 1979, page C7-577 SPIKY DENSITY FLUCTUATION AND RELAXATIONOSCILLATIONINAN ANOMALOUSLY RESISTIVE PHASE

    E-print Network

    Boyer, Edmond

    a in Fig. 1. A 400 mW microwave of frequen ularly to the plasma column with the wave of the magnetic field) means of microwave s c a t t e r i n g technique co e t a1.3) which predicted t h e existence of l o c t e n t i a l jumps (double Layers) and gmuir turbulence generated i n an anomalous- l y r e s i s t i

  16. Properties of microwave plasma torch operating at a low pressure

    SciTech Connect

    Cho, Soon C.; Uhm, Han S.; Hong, Yong C.; Kim, Jae H. [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

    2008-10-15

    A microwave plasma torch system is attached to a low-pressure chamber in this study. The electric field induced in a quartz discharge tube by microwave radiation breaks down the gas at a sufficiently low pressure, igniting the plasma, which is continuously sustained by the microwave radiation. The plasma profile at a very low pressure is shown to be asymmetric with higher density on the incoming side of the microwaves. The gas temperature at the bright spot of the torch plasma measured via the optical emission from hydroxide radicals is shown to increase drastically upon high-pressure operation as the microwave power increases. The electron density at the torch flame is measured by recording the Stark broadening of the hydrogen Balmer beta line. The plasma density increases as the microwave power increases. The typical argon plasma density of a plasma torch powered at 500 W under a pressure of 150 Torr is on the order of 10{sup 14}/cm{sup 3}. The electron temperature in the argon torch plasma was estimated to be 1.5 eV, thereby effectively exciting the molecules in the torch gas. Disintegration of nitrogen fluoride (NF{sub 3}) indicates that a microwave plasma torch operating at a low pressure can efficiently generate an abundant amount of chemical radicals.

  17. IDENTIFYING THE RADIO BUBBLE NATURE OF THE MICROWAVE HAZE

    SciTech Connect

    Dobler, Gregory, E-mail: dobler@kitp.ucsb.edu [Kavli Institute for Theoretical Physics, University of California, Santa Barbara Kohn Hall, Santa Barbara, CA 93106 (United States)

    2012-11-20

    Using seven-year data from the Wilkinson Microwave Anisotropy Probe, I identify a sharp 'edge' in the microwave haze at high southern Galactic latitude (-55 Degree-Sign < b < -35 Degree-Sign ) that is spatially coincident with the southern edge of the 'Fermi haze/bubbles'. This finding proves conclusively that the edge in the gamma rays is real (and not a processing artifact), demonstrates explicitly that the microwave haze and the gamma-ray bubbles are indeed the same structure observed at multiple wavelengths, and strongly supports the interpretation of the microwave haze as a separate component of Galactic synchrotron (likely generated by a transient event) as opposed to a simple variation of the spectral index of disk synchrotron. In addition, combining these data sets allows for the first determination of the magnetic field within a radio bubble using microwaves and gamma rays by taking advantage of the fact that the inverse Compton gamma rays are primarily generated by scattering of cosmic microwave background photons at these latitudes, thus minimizing uncertainty in the target radiation field. Assuming uniform volume emissivity, I find that the magnetic field within the southern Galactic microwave/gamma-ray bubble is {approx}5 {mu}G above 6 kpc off of the Galactic plane.

  18. Development and performance evaluation of CE-1 satellite microwave sounder

    NASA Astrophysics Data System (ADS)

    Wei, Guo; Jiang, Jingshan; Zhang, Xiaohui; Zhang, Dehai; Chuandong, Xu

    The CE-1 is the first Lunar orbit satellite for the Moon exploring task of the Chinese ChangE Project. The CE-1 Microwave Sounder is a microwave radiometer used to measure the thermal emission of the Moon at four frequencies(3,7.8,19.35 and 37GHz), the measurement results is assumed to obtain the brightness temperature map of the whole Moon and analyze the thickness of the Moon soil. In this paper, the development of the CE-1 microwave radiometer is presented, including the antennas and the receiver design, as well as the system integration. Before the satellite launch, the microwave sounder has implemented rigorous ground test and calibration experiment, including thermal/vacuum test. Based upon two point calibration approach, the hardware radiative transfer model has been constructed, and the experiment results and the performance evaluation of the microwave sounder are also presented in this paper. By analyzing the results and the inflight measurement, the CE-1 microwave sounder has obtain the whole Moon brightness temperature map with the analysis of the Moon soil thickness. It shows that the precision and the accuracy of microwave sounder are approximately 1K, and assure the Moon exploring task is successfully proceeding

  19. Infrared emission spectroscopy of CO2 at high temperature. Part II: Experimental results and

    E-print Network

    Paris-Sud XI, Université de

    ) 14-25" DOI : 10.1016/j.jqsrt.2011.09.013 #12;Key words: FTIR emission spectroscopy, microwave plasma spectroscopic databases is carried out in terms of vibrational and rotational energy cutoff and total band emission measurements using a microwave post-discharge in CO2 flow as emission source. The measurements

  20. ECE 585: MICROWAVE ENGINEERING II Spring 2011

    E-print Network

    Massachusetts at Amherst, University of

    . Teaching Assistant: Anthony Swochak Textbook: Microwave Engineering, 3rd ed., 2005, David Pozar, JohnECE 585: MICROWAVE ENGINEERING II Spring 2011 Major Course Topics Multiport Microwave Devices] Prerequisites: Microwave Engineering I (ECE 584) or equivalent Instructor: Stephen Frasier frasier

  1. Observation of Anomalous Ion Heating by Broadband Drift-Wave Turbulence

    SciTech Connect

    Enge, S.; Birkenmeier, G.; Manz, P.; Ramisch, M.; Stroth, U. [Institut fuer Plasmaforschung, Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2010-10-22

    Using laser induced fluorescence and passive spectroscopy on a magnetically confined low-temperature plasma, anomalous ion heating is observed which exceeds collisional heating from the electrons by a factor of up to five. Direct wave heating due to the 2.45 GHz microwave as well as stochastic heating by large-amplitude fluctuations could be ruled out as explanations. Good quantitative agreement is found when comparing the missing power in the ion species with heating power due to the dissipation of drift-wave turbulence. This turbulent energy transfer into the ion channel could have important consequences for the interpretation of transport in fusion plasmas.

  2. Broadband anomalous reflection based on gradient low-Q meta-surface

    NASA Astrophysics Data System (ADS)

    Pu, Mingbo; Chen, Po; Wang, Changtao; Wang, Yanqin; Zhao, Zeyu; Hu, Chenggang; Huang, Cheng; Luo, Xiangang

    2013-05-01

    Gradient-index metamaterial is crucial in the spatial manipulation of electromagnetic wave. Here we present an efficient approach to extend the bandwidth of phase modulation by utilizing the broadband characteristic of low-quality (Q) meta-surface in the reflection mode. The dispersion of the meta-surface is engineered to compensate the phase difference induced by frequency change. Meanwhile, a thin gradient index cover layer is added on the top of meta-surface to extend the phase modulation range to cover the entire [0, 360°]. As a proof of concept, anomalous nearly perfect reflection with relative bandwidth near 40% is demonstrated in the microwave regime.

  3. Probability Density of the Multipole Vectors for a Gaussian Cosmic Microwave Background

    E-print Network

    Mark R. Dennis; Kate Land

    2007-08-09

    We review Maxwell's multipole vectors, and elucidate some of their mathematical properties, with emphasis on the application of this tool to the cosmic microwave background (CMB). In particular, for a completely random function on the sphere (corresponding to the statistically isotropic Gaussian model of the CMB), we derive the full probability density function of the multipole vectors. This function is used to analyze the internal configurations of the third-year Wilkinson Microwave Anisotropy Probe quadrupole and octopole, and we show the observations are consistent with the Gaussian prediction. A particular aspect is the planarity of the octopole, which we find not to be anomalous.

  4. Determination of soluble toxic arsenic species in alga samples by microwave-assisted extraction and high performance liquid chromatography–hydride generation–inductively coupled plasma-atomic emission spectrometry

    Microsoft Academic Search

    S. García Salgado; M. A. Quijano Nieto; M. M. Bonilla Simón

    2006-01-01

    A microwave-based procedure for arsenic species extraction in alga samples (Sargassum fulvellum, Chlorella vulgaris, Hizikia fusiformis and Laminaria digitata) is described. Extraction time and temperature were tested in order to evaluate the extraction efficiency of the process. Arsenic compounds were extracted in 8ml of deionised water at 90°C for 5min. The process was repeated three times. Soluble arsenic compounds extracted

  5. Anomalous fluctuations and partial coherency

    NASA Astrophysics Data System (ADS)

    Blažek, Mikuláš

    2001-02-01

    Partially coherent statistical distributions allow to describe the processes appearing in between the pure coherent (Poisson) and pure stochastic (Pascal or negative binomial) multiparticle production. In the past, their successful rôle in describing the data which came from different types of high energy collisions, was appreciated many times. However, the corresponding distributions usually involve average numbers of particles and thereby the information on the intermittency (considered as anomalous fluctuations in the particle density) is smeared out already at the input step. It is the purpose of the present contribution to suggest such a procedure, in frame of the quantum statistics, which takes properly into account the different number of particles produced in different bins. Taking those numbers from experimental data, the value and the trend of the parameters specifying the partial coherence can be deduced. Some first results obtained from the analysis of the data on high energy nucleus-nucleus collisions, are included, too.

  6. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 40, NO. 2, FEBRUARY 2002 515 The Dependence of Nadir Ocean Surface Emissivity on

    E-print Network

    Ruf, Christopher

    The Dependence of Nadir Ocean Surface Emissivity on Wind Vector as Measured With Microwave Radiometer Ngan Tran observations of TOPEX/Po- seidon microwave radiometer (TMR) at 18, 21, and 37 GHz have been col- located/Poseidon microwave radiometer (TMR). I. INTRODUCTION The TOPEX/Poseidon microwave radiometer (TMR) is a three

  7. Design of a microwave calorimeter for the microwave tokamak experiment

    SciTech Connect

    Marinak, M. (California Univ., Berkeley, CA (USA))

    1988-10-07

    The initial design of a microwave calorimeter for the Microwave Tokamak Experiment is presented. The design is optimized to measure the refraction and absorption of millimeter rf microwaves as they traverse the toroidal plasma of the Alcator C tokamak. Techniques utilized can be adapted for use in measuring high intensity pulsed output from a microwave device in an environment of ultra high vacuum, intense fields of ionizing and non-ionizing radiation and intense magnetic fields. 16 refs.

  8. Anomalous Sediment Mixing by Bioturbation

    NASA Astrophysics Data System (ADS)

    Roche, K. R.; Aubeneau, A. F.; Xie, M.; Packman, A. I.

    2013-12-01

    Bioturbation, the reworking of sediments by animals and plants, is the dominant mode of sediment mixing in low-energy environments, and plays an important role in sedimentary biogeochemical processes. Mixing resulting from bioturbation has historically been modeled as a diffusive process. However, diffusion models often do not provide a sufficient description of sediment mixing due to bioturbation. Stochastic models, such as the continuous time random walk (CTRW) model, provide more general descriptions of mixing behavior that are applicable even when regular diffusion assumptions are not met. Here we present results from an experimental investigation of anomalous sediment mixing by bioturbation in freshwater sediments. Clean and heavy-metal-contaminated sediments were collected from Lake DePue, a backwater lake of the Illinois River. The burrowing worm species Lumbriculus variegatus was introduced to homogenized Lake DePue sediments in aerated aquaria. We then introduced inert fine fluorescent particles to the sediment-water interface. Using time-lapse photography, we observed the mixing of the fluorescent particles into the sediment bed over a two-week period. We developed image analysis software to characterize the concentration distribution of the fluorescent particles as a function of sediment depth, and applied this to the time-series of images to evaluate sediment mixing. We fit a one-dimensional CTRW model to the depth profiles to evaluate the underlying statistical properties of the mixing behavior. This analysis suggests that the sediment mixing caused by L. variegatus burrowing is subdiffusive in time and superdiffusive in space. We also found that heavy metal contamination significantly reduces L. variegatus burrowing, causing increasingly anomalous sediment mixing. This result implies that there can be important feedbacks between sediment chemistry, organism behavior, and sediment mixing that are not considered in current environmental models.

  9. A blended land emissivity product from the Inter-Comparison of different Land Surface Emissivity Estimates

    NASA Astrophysics Data System (ADS)

    Norouzi, H.; Temimi, M.; Khanbilvardi, R.

    2012-12-01

    Passive microwave observations are routinely used to estimate rain rate, cloud liquid water, and total precipitable water. In order to have accurate estimations from microwave, the contribution of the surface should be accounted for. Over land, due to the complex interaction between the microwave signal and the soil surface, retrieval of land surface emissivity and other surface and subsurface parameters is not straightforward. Several microwave emissivity products from various microwave sensors have been proposed. However, lack of ground truth measurements makes the validation of these products difficult. This study aims to inter-compare several available emissivity products over land and ultimately proposes a unique blended product that overcomes the flaws of each individual product. The selected products are based on observations from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), the Special Sensor Microwave Imager (SSM/I), the Advanced Microwave Sounding unit (AMSU), and the Special Sensor Microwave Imager/Sounder (SSMIS). In retrieval of emissivities from these sensors different methods and ancillary data have been used. Some inherent discrepancies between the selected products can be introduced by as the difference in geometry in terms of incident angle, spectral response, and the foot print size which can affect the estimations. Moreover, ancillary data especially skin temperature and cloud mask cover can cause significant discrepancies between various estimations. The time series and correlation between emissivity maps are explored to assess the consistency of emissivity variations with geophysical variable such as snow, precipitation and drought. Preliminary results reveal that inconsistency between products varies based on land cover type due to penetration depth effect and ancillary data. Six years of estimations are employed in this research study, and a global blended emissivity estimations based on all product with minimal discrepancies is proposed.

  10. Recent Developments in Astrophysical and Cosmological Exploitation of Microwave Surveys

    NASA Astrophysics Data System (ADS)

    Burigana, Carlo; Davies, Rodney D.; de Bernardis, Paolo; Delabrouille, Jacques; de Paolis, Francesco; Douspis, Marian; Khatri, Rishi; Liu, Guo Chin; Maris, Michele; Masi, Silvia; Mennella, Aniello; Natoli, Paolo; Norgaard-Nielsen, Hans Ulrik; Pointecouteau, Etienne; Rephaeli, Yoel; Toffolatti, Luigi

    2015-01-01

    In this article we focus on the astrophysical results and the related cosmological implications derived from recent microwave surveys, with emphasis to those coming from the Planck mission. We critically discuss the impact of systematics effects and the role of methods to separate the cosmic microwave background signal from the astrophysical emissions and each different astrophysical component from the others. We then review of the state of the art in diffuse emissions, extragalactic sources, cosmic infrared background, and galaxy clusters, addressing the information they provide to our global view of the cosmic structure evolution and for some crucial physical parameters, as the neutrino mass. Finally, we present three different kinds of scientific perspectives for fundamental physics and cosmology offered by the analysis of on-going and future cosmic microwave background projects at different angular scales dedicated to anisotropies in total intensity and polarization and to absolute temperature.

  11. Microwave and gamma radiation observations of soil moisture

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Njoku, E. G.; Peck, E.; Ulaby, F. T.

    1979-01-01

    The unique dielectric properties of water at microwave wavelengths afford the possibility for remotely sensing the moisture content in the surface layer of the soil. The surface emissivity and reflectivity for the soils at these wavelengths are strong functions of its moisture content. The changes in emissivity can be observed by passive microwave techniques (radiometry) and the change in reflectivity can be observed by active microwave techniques (radar). The difference in the natural terrestrial gamma ray flux measured for wet and dry soil may be used to determine soil moisture. The presence of water moisture in the soil causes an effective increase in soil density, resulting in an increased attenuation of the gamma flux for wet soil and a corresponding lower flux above the ground surface.

  12. Satellite Remote Sensing: Passive-Microwave Measurements of Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

    2001-01-01

    Satellite passive-microwave measurements of sea ice have provided global or near-global sea ice data for most of the period since the launch of the Nimbus 5 satellite in December 1972, and have done so with horizontal resolutions on the order of 25-50 km and a frequency of every few days. These data have been used to calculate sea ice concentrations (percent areal coverages), sea ice extents, the length of the sea ice season, sea ice temperatures, and sea ice velocities, and to determine the timing of the seasonal onset of melt as well as aspects of the ice-type composition of the sea ice cover. In each case, the calculations are based on the microwave emission characteristics of sea ice and the important contrasts between the microwave emissions of sea ice and those of the surrounding liquid-water medium.

  13. Analysis of Electron and Microwave Behavior in Microwave Discharge Neutralizer

    Microsoft Academic Search

    Hirokazu Masui; Yousuke Tashiro; Naoji Yamamoto; Hideki Nakashima; Ikkoh Funaki

    2006-01-01

    In the MUCES-C mission conducted by JAXA (Japan Aero Exploration Agency), a microwave neutralizer is mounted with a microwave ion engine on the HAYABUSA space probe. The neutralizer consists of an L-shaped antenna to inject microwaves and samarium cobalt magnets to provide ECR (electron cyclotron resonance). Plasma production of a higher density than the cutoff density is expected in the

  14. Detecting WIMPs in the Microwave Sky

    E-print Network

    P. Blasi; A. V. Olinto; C. Tyler

    2002-02-05

    The hierarchical clustering observed in cold dark matter simulations results in highly clumped galactic halos. If the dark matter in our halo is made of weakly interacting massive particles (WIMPs), their annihilation products should be detectable in the higher density and nearby clumps. We consider WIMPs to be neutralinos and calculate the synchrotron flux from their annihilation products in the presence of the Galactic magnetic field. We derive a self-consistent emission spectrum including pair annihilation, synchrotron self-absorption, and synchrotron self-Compton reactions. The resulting radiation spans microwave frequencies that can be observed over the anisotropies in the cosmic microwave background. These synchrotron sources should be identifiable as WIMP clumps, either by their spatial structure or by their distinctive radio spectrum.

  15. Passive microwave studies of frozen lakes

    NASA Technical Reports Server (NTRS)

    Hall, D. K.; Foster, J. L.; Rango, A.; Chang, A. T. C.

    1978-01-01

    Lakes of various sizes, depths and ice thicknesses in Alaska, Utah and Colorado were overflown with passive microwave sensors providing observations at several wavelengths. A layer model is used to calculate the microwave brightness temperature, T sub B (a function of the emissivity and physical temperatures of the object), of snowcovered ice underlain with water. Calculated T sub B's are comparable to measured T sub B's. At short wavelengths, e.g., 0.8 cm, T sub B data provide information on the near surface properties of ice covered lakes where the long wavelength, 21.0 cm, observations sense the entire thickness of ice including underlying water. Additionally, T sub B is found to increase with ice thickness. 1.55 cm observations on Chandalar Lake in Alaska show a T sub B increase of 38 K with an approximate 124 cm increase in ice thickness.

  16. Enhanced window breakdown dynamics in a nanosecond microwave tail pulse

    SciTech Connect

    Chang, Chao, E-mail: changc02@mails.tsinghua.edu.cn [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China); Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Zhu, Meng; Li, Shuang; Xie, Jialing; Yan, Kai; Luo, Tongding; Zhu, Xiaoxin [Laboratory on Science and Technology of High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China); Verboncoeur, John, E-mail: johnv@msu.edu [Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States)

    2014-06-23

    The mechanisms of nanosecond microwave-driven discharges near a dielectric/vacuum interface were studied by measuring the time- and space-dependent optical emissions and pulse waveforms. The experimental observations indicate multipactor and plasma developing in a thin layer of several millimeters above interface. The emission brightness increases significantly after main pulse, but emission region widens little. The mechanisms are studied by analysis and simulation, revealing intense ionization concentrated in a desorbed high-pressure layer, leading to a bright light layer above surface; the lower-voltage tail after main pulse contributes to heat electron energy tails closer to excitation cross section peaks, resulting in brighter emission.

  17. Refinement of microwave vegetation indices

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous investigations have established the basis for a new type of vegetation index based on passive microwave satellite observations. These microwave vegetation indices (MVIs) have been qualitatively evaluated by examining global spatial and seasonal temporal features. Limited quantitative studie...

  18. MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS

    EPA Science Inventory

    Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

  19. MICROWAVE INSPECTION OF CIVIL STRUCTURES

    Microsoft Academic Search

    F. Volgyi

    This paper is devoted to microwave moisture-measurement (aquametry) and composition estimation of civil structures. In recent years considerable efforts have been made in applying microwave technique to test dielectric materials and metals. The first part of this \\

  20. Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

    NASA Technical Reports Server (NTRS)

    Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

  1. Microwave Thermoelastic Tomography and Imaging

    Microsoft Academic Search

    James C. Lin

    Microwave thermoelastic imaging uses microwave-pulse-induced thermoelastic pressure waves to form planar or tomographic images.\\u000a Since the generation and detection of thermoelastic pressure waves depends on dielectric permittivity, specific heat, thermal\\u000a expansion, and acoustic properties of tissue, microwave thermoelastic imaging possesses the characteristic features of a duel-modality\\u000a imaging system. The unique attributes of the high contrast offered by microwave absorption and

  2. Microwave Ablation of Hepatic Malignancy

    PubMed Central

    Lubner, Meghan G.; Brace, Christopher L.; Ziemlewicz, Tim J.; Hinshaw, J. Louis; Lee, Fred T.

    2013-01-01

    Microwave ablation is an extremely promising heat-based thermal ablation modality that has particular applicability in treating hepatic malignancies. Microwaves can generate very high temperatures in very short time periods, potentially leading to improved treatment efficiency and larger ablation zones. As the available technology continues to improve, microwave ablation is emerging as a valuable alternative to radiofrequency ablation in the treatment of hepatic malignancies. This article reviews the current state of microwave ablation including technical and clinical considerations. PMID:24436518

  3. Measurements of plasma potential in high-pressure microwave plasmas

    Microsoft Academic Search

    A. V. Tarasova; N. K. Podder; E. J. Clothiaux

    2009-01-01

    Plasma potential of a high-pressure (~1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of

  4. Measurements of plasma potential in high-pressure microwave plasmas

    Microsoft Academic Search

    A. V. Tarasova; N. K. Podder; E. J. Clothiaux

    2009-01-01

    Plasma potential of a high-pressure (?1 Torr) microwave-generated argon plasma is measured using a Langmuir probe and a cold emissive probe. The operation of a hot emissive probe in a high-pressure plasma has been very difficult due to frequent burn-outs and significantly reduced lifetime of the probe filament, which, in turn, limits the possibility of collecting a wide range of

  5. A simple solar microwave burst observed with high spectral resolution

    NASA Technical Reports Server (NTRS)

    Gary, Dale E.; Hurford, G. J.

    1989-01-01

    A small flare that occurred on February 3, 1986 which was dominated by a single homogeneous source is analyzed. The theory of microwave emission from homogeneous sources was used to trace the evolution of the burst. The spectral profile indicates a thermal origin. It was found that the source expanded with time during the burst.

  6. Geostationary microwave sounder requirements

    NASA Astrophysics Data System (ADS)

    Chu, Donald; Grody, Norman C.; Madden, Michael; Susskind, Joel; Blackwell, William J.

    2004-12-01

    The National Oceanic and Atmospheric Administration (NOAA) is considering a microwave radiometer for the next series of Geostationary Operational Environmental Satellites (GOES-R) to be launched starting in 2012. This paper examines the products proposed for the geostationary microwave radiometer in the light of current microwave retrieval algorithms and estimates the performance achievable from geostationary altitude with a three-meter antenna. The results suggest that hemispheric soundings and rain rates can be generated on an hourly basis with the desired accuracy and horizontal resolution, that capping inversions can be detected in conjunction with infrared soundings, that hurricane warm core temperatures can be resolved using high frequencies plus deconvolution and that ocean wind and total precipitable water products can be provided with close to the desired resolution.

  7. RFTF ECH microwave system

    SciTech Connect

    Bigelow, T.S.; White, T.L.; Kimrey, H.D.

    1986-01-01

    A Radio-Frequency Test Facility (RFTF) has recently been constructed at Oak Ridge National Laboratory (ORNL) for development and testing of Ion Cyclotron Heating (ICH) antennas under realistic fusion reactor plasma edge conditions. High-power ICH antennas must be immersed in the plasma for proper coupling of rf power and therefore are subject to particle bombardment and heat flux. In RFTF, plasma is generated and heated by electron cyclotron resonance heating (ECRH) with 28-GHz microwave power from a gyrotron tube. The plasma is confined in a simple magnetic mirror formed by two superconducting coils surrounding a box-shaped vacuum vessel. Using 50 kW of microwave power, a plasma with density of 5 x 10/sup 11/ cm/sup 3/ and temperature of 8 eV is obtained, a fairly good fusion research edge plasma. This presentation covers the microwave generation and transmission system plus some of the electron cyclotron heated (ECH) results on RFTF.

  8. Cosmic Microwave Background Polarization

    E-print Network

    Arthur Kosowsky

    1995-02-03

    Polarization of the cosmic microwave background, though not yet detected, provides a source of information about cosmological parameters complementary to temperature fluctuations. This paper provides a complete theoretical treatment of polarization fluctuations. After a discussion of the physics of polarization, the Boltzmann equation governing the evolution of the photon density matrix is derived from quantum theory and applied to microwave background fluctuations, resulting in a complete set of transport equations for the Stokes parameters from both scalar and tensor metric perturbations. This approach is equivalent at lowest order in scattering kinematics to classical radiative transfer, and provides a general framework for treating the cosmological evolution of density matrices. The metric perturbations are treated in the physically appealing longitudinal gauge. Expressions for various temperature and polarization correlation functions are derived. Detection prospects and theoretical utility of microwave background polarization are briefly discussed.

  9. Non-standard morphological relic patterns in the cosmic microwave background

    E-print Network

    Joe Zuntz; James P. Zibin; Caroline Zunckel; Jonathan Zwart

    2011-03-31

    Statistically anomalous signals in the microwave background have been extensively studied in general in multipole space, and in real space mainly for circular and other simple patterns. In this paper we search for a range of non-trivial patterns in the temperature data from WMAP 7-year observations. We find a very significant detection of a number of such features and discuss their consequences for the essential character of the cosmos.

  10. Uniformity Issue in Microwave Drying

    Microsoft Academic Search

    Z. Y. Li; R. F. Wang; T. Kudra

    2011-01-01

    Microwave drying is an advanced drying technique in which heat is generated inside the material due to transformation of high-frequency electromagnetic energy so the liquid moisture is intensively evaporated and transported toward the material surface. However, an inherent problem in microwave drying is nonuniform heat generation, which leads to uneven drying. In this article, the factors causing nonuniform microwave heating

  11. Physics of the Microwave Oven

    ERIC Educational Resources Information Center

    Vollmer, Michael

    2004-01-01

    This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

  12. Microwave-assisted Chemical Transformations

    EPA Science Inventory

    In recent years, there has been a considerable interest in developing sustainable chemistries utilizing green chemistry principles. Since the first published report in 1986 by Gedye and Giguere on microwave assisted synthesis in household microwave ovens, the use of microwaves as...

  13. Microwave Schottky Ralph J. Pasquinelli

    E-print Network

    Large Hadron Collider Program

    Microwave Schottky Pickups at Fermilab Ralph J. Pasquinelli May 9, 2003 #12;5/9/03 LARP #12;5/9/03 LARP Collaboration R. J. Pasquinelli Microwave Schottky Pickups Slotted Waveguide Pickup 1.7 GHz 109 x 75 mm aperture #12;5/9/03 LARP Collaboration R. J. Pasquinelli Microwave Schottky Pickups

  14. Microwave superheaters for fusion

    NASA Astrophysics Data System (ADS)

    Campbell, R. B.; Hoffman, M. A.; Logan, B. G.

    1987-10-01

    The microwave superheater uses the synchrotron radiation from a thermonuclear plasma to heat gas seeded with an alkali metal to temperatures far above the temperature of material walls. It can improve the efficiency of the Compact Fusion Advanced Rankine (CFAR) cycle described elsewhere in these proceedings. For a proof-of-principle experiment using helium, calculations show that a gas superheat delta T of 2000 K is possible when the wall temperature is maintained at 1000 K. The concept can be scaled to reactor grade systems. Because of the need for synchrotron radiation, the microwave superheater is best suited for use with plasmas burning an advanced fuel such as D He-3.

  15. EDITORIAL: Microwave Moisture Measurements

    NASA Astrophysics Data System (ADS)

    Kaatze, Udo; Kupfer, Klaus; Hübner, Christof

    2007-04-01

    Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precise measurements of the water content are thus extremely useful in pure sciences, particularly in biochemistry and biophysics. They are likewise important in many agricultural, technical and industrial fields. Applications are broad and diverse, and include the quality assessment of foodstuffs, the determination of water content in paper, cardboard and textile production, the monitoring of moisture in sands, gravels, soils and constructions, as well as the measurement of water admixtures to coal and crude oil in reservoirs and in pipelines. Microwave moisture measurements and evaluations require insights in various disciplines, such as materials science, dielectrics, the physical chemistry of water, electrodynamics and microwave techniques. The cooperation of experts from the different fields of science is thus necessary for the efficient development of this complex discipline. In order to advance cooperation the Workshop on Electromagnetic Wave Interaction with Water and Moist Substances was held in 1993 in Atlanta. It initiated a series of international conferences, of which the last one was held in 2005 in Weimar. The meeting brought together 130 scientists and engineers from all over the world. This special issue presents a collection of some selected papers that were given at the event. The papers cover most topics of the conference, featuring dielectric properties of aqueous materials, electromagnetic wave interactions, measurement methods and sensors, and various applications. The special issue is dedicated to Dr Andrzej W Kraszewski, who died in July 2006 after a distinguished career of 48 years in the research of microwave applications. Dr Kraszewski was a pioneer in moisture content sensing and the founder of microwave aquametry. He organized the first conferences on electromagnetic wave interactions with water and moist substances and helped to maintain the progress of microwave aquametry research internationally. Andrzej Kraszewski is missed by the microwave moisture measurement community who appreciated both his unusual technical ability and his pleasant and endearing character. Andrzej W Kraszewski, 1933-2006 We hope you will enjoy reading these papers and will extend your scientific curiosity to this field. Finally, we would like to thank all the authors, referees and the staff of Measurement Science and Technology for their contributions and support which have made the publication of this special issue possible.

  16. Microwave Frequency Polarizers

    NASA Technical Reports Server (NTRS)

    Ha, Vien The; Mirel, Paul; Kogut, Alan J.

    2013-01-01

    This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

  17. Microwave luneburg lens.

    PubMed

    Gunderson, L C; Holmes, G T

    1968-05-01

    This article describes a two-dimensional Luneburg lens, fabricated from steps of foam glass of different refractive index as an approximation to a continuous index gradient. This is an improvement over lenses fabricated by assembly of machined parts, which unavoidably contain some air gaps, resulting in different path lengths through the lens. The foam glass lens is superior to a plastic lens since it is able to withstand higher temperatures and hence higher powers, in addition to having superior aging characteristics. Measurements have been made throughout the microwave band, and the results clearly establish the feasibility of this fabrication technique for the construction of a microwave Luneburg lens. PMID:20068688

  18. Cosmic Microwave Background

    NSDL National Science Digital Library

    In this lesson, students explore the cosmic microwave background to understand why it permeates the universe and why it peaks as microwave radiation. Students should be able to explain that the origin of the background radiation is the uniform thermal radiation of the big bang and that the radiation produced was evenly distributed around the small early universe, causing it to permeate today's universe. This activity is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1965 Cosmic Times Poster.

  19. Emissivity corrected infrared method for imaging anomalous structural heat flows

    DOEpatents

    Del Grande, N.K.; Durbin, P.F.; Dolan, K.W.; Perkins, D.E.

    1995-08-22

    A method for detecting flaws in structures using dual band infrared radiation is disclosed. Heat is applied to the structure being evaluated. The structure is scanned for two different wavelengths and data obtained in the form of images. Images are used to remove clutter to form a corrected image. The existence and nature of a flaw is determined by investigating a variety of features. 1 fig.

  20. Emissivity corrected infrared method for imaging anomalous structural heat flows

    DOEpatents

    Del Grande, Nancy K. (San Leandro, CA); Durbin, Philip F. (Livermore, CA); Dolan, Kenneth W. (Livermore, CA); Perkins, Dwight E. (Livermore, CA)

    1995-01-01

    A method for detecting flaws in structures using dual band infrared radiation. Heat is applied to the structure being evaluated. The structure is scanned for two different wavelengths and data obtained in the form of images. Images are used to remove clutter to form a corrected image. The existence and nature of a flaw is determined by investigating a variety of features.

  1. Anomalous currents in dense matter under a magnetic field

    E-print Network

    Deog Ki Hong

    2010-12-31

    We consider fermionic dense matter under a magnetic field, where fermions couple minimally to gauge fields, and calculate anomalous currents at one loop. We find anomalous currents are spontaneously generated along the magnetic field but fermions only in the lowest Landau level contribute to anomalous currents. We then show that there are no more corrections to the anomalous currents from two or higher loops.

  2. ACS SBC Recovery from Anomalous Shutdown

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2012-10-01

    This proposal is designed to permit recovery of the SBC {FUV MAMA} detector after an anomalous shutdown. Anomalous shutdowns can occur as a result of bright object violations which trigger the Bright Scene Detection or Software Global Monitor. Anomalous shutdowns can also occur as a result of SBC hardware problems. The recovery from anomalous shutdown procedure consists of four tests: 1} a signal processing electronics check, 2} a slow high voltage ramp-up to an intermediate voltage, 3} a slow high-voltage ramp-up to the full operating voltage, and 4} a Fold Test. During the two high-voltage ramp-ups, dark ACCUM exposures are taken. At high voltage, dark ACCUM exposures and diagnostics are taken. This proposal is based on Proposal 12738 from Cycle 19.

  3. ACS SBC Recovery from Anomalous Shutdown

    NASA Astrophysics Data System (ADS)

    Wheeler, Thomas

    2010-09-01

    This proposal is designed to permit recovery of the SBC {FUV MAMA} detector after an anomalous shutdown. Anomalous shutdowns can occur as a result of bright object violations which trigger the Bright Scene Detection or Software Global Monitor. Anomalous shutdowns can also occur as a result of SBC hardware problems. The recovery from anomalous shutdown procedure consists of four tests: a signal processing electronics check, a slow high voltage ramp-up to an intermediate voltage, a slow high-voltage ramp-up to the full operating voltage, and lastly, a Fold Test. During the two high-voltage ramp-ups, dark ACCUM exposures are taken. At high voltage, dark ACCUM exposures and diagnostics are taken. This proposal is based on proposal 11884, visits 1 to 4.

  4. ORIGINAL ARTICLE Torsional Anomalous Retinal Correspondence

    E-print Network

    Peli, Eli

    anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional documented torsional strabismus and torsional HARC. Methods. Monocular visual fields under binocular fixation strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared

  5. Anomalous Diffraction in Crystallographic Phase Evaluation

    PubMed Central

    Hendrickson, Wayne A.

    2014-01-01

    X-ray diffraction patterns from crystals of biological macromolecules contain sufficient information to define atomic structures, but atomic positions are inextricable without having electron-density images. Diffraction measurements provide amplitudes, but the computation of electron density also requires phases for the diffracted waves. The resonance phenomenon known as anomalous scattering offers a powerful solution to this phase problem. Exploiting scattering resonances from diverse elements, the methods of multiwavelength anomalous diffraction (MAD) and single-wavelength anomalous diffraction (SAD) now predominate for de novo determinations of atomic-level biological structures. This review describes the physical underpinnings of anomalous diffraction methods, the evolution of these methods to their current maturity, the elements, procedures and instrumentation used for effective implementation, and the realm of applications. PMID:24726017

  6. Tensor charge and anomalous magnetic moment correlation

    E-print Network

    M. Mekhfi

    2005-10-05

    We propose a generalization of the upgraded Karl- Sehgal formula which relates baryon magnetic moments to the spin structure of constituent quarks, by adding anomalous magnetic moments of quarks. We first argue that relativistic nature of quarks inside baryons requires introduction of two kinds of magnetisms, one axial and the other tensoriel. The first one is associated with integrated quark helicity distributions (standard) and the second with integrated transversity distributions . The weight of each contribution is controlled by the combination of two parameters, xi the ratio of the quark mass to the average kinetic energy Ei and ai the quark anomalous magnetic moment. The quark anomalous magnetic moment is correlated to transversity and both are necessary ingredients in describing relativistic quarks. The proposed formula, then when confronted with baryon magnetic moments data with reasonable inputs, yields beside quark magnetic densities, anomalous magnetic moments enough large to not be ignored.

  7. Anomalous behaviour of molybdenum in steel welds

    E-print Network

    Choudhary, Habib Ullah

    The addition of molybdenum to steel welds in quite small concentrations leads to a variety of anomalous microstructural and mechanical property effects. In some cases, the effects manifest even when there are no obvious changes in microstructure...

  8. Anomalous transport through porous and fractured media

    E-print Network

    Kang, Peter Kyungchul

    2014-01-01

    Anomalous transport, understood as the nonlinear scaling with time of the mean square displacement of transported particles, is observed in many physical processes, including contaminant transport through porous and fractured ...

  9. BRST quantization of anomalous gauge theories

    E-print Network

    Nelson R. F. Braga

    1995-02-07

    It is shown how the BRST quantization can be applied to a gauge invariant sector of theories with anomalously broken symmetries. This result is used to show that shifting the anomalies to a classically trivial sector of fields (Wess-Zumino mechanism) makes it possible to quantize the physical sector using a standard BRST procedure, as for a non anomalous theory. The trivial sector plays the role of a topological sector if the system is quantized without shifting the anomalies.

  10. Variable frequency microwave furnace system

    DOEpatents

    Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

    1994-01-01

    A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

  11. Local microwave background radiation

    E-print Network

    Domingos Soares

    2014-11-13

    An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

  12. Microwave magnetoelectric fields

    E-print Network

    Kamenetskii, E O

    2011-01-01

    We show that in a source-free subwavelength region of microwave fields there can exist the field structures with local coupling between the time-varying electric and magnetic fields differing from the electric-magnetic coupling in regular-propagating free-space electromagnetic waves. To distinguish such field structures from regular electromagnetic (EM) field structures, we term them as magnetoelectric (ME) fields. We study a structure and conservation laws of microwave ME near fields. We show that there exist sources of microwave ME near fields - the ME particles. These particles are represented by small quasi-2D ferrite disks with the magnetic-dipolar-oscillation spectra. The near fields originated from such particles are characterized by topologically distinctive power-flow vortices, non-zero helicity, and a torsion degree of freedom. Our studies of the microwave ME near fields are combined in two successive papers. In this paper we give a theoretical background of properties of the electric and magnetic f...

  13. Commercial microwave space power

    Microsoft Academic Search

    J. Siambis; W. Gregorwich; S. Walmsley; K. Shockey; K. Chang

    1991-01-01

    The authors present and investigate a current technology design point for beamed microwave commercial space power. The design point requires that 25 kW be delivered to the user load with 30 percent overall system efficiency. The key elements of the design are: an efficient rectenna at the user end; a high gain, low beam width, efficient antenna at the central

  14. MICROWAVE RESONANCES IN DNA

    EPA Science Inventory

    This report describes spectroscopic studies of DNA which were undertaken to better understand a physical basis for microwave absorption by this molecule. hree types of studies are described. ) The low frequency scattered light spectrum of DNA was studied by two methods. irst, Ram...

  15. Satellite microwave remote sensing

    SciTech Connect

    Allen, T.D.

    1983-01-01

    This work discusses satellite remote sensing with global applications. Presents and assesses the research findings of the SEASAT Users Group of Europe which carried out experiments over European sites. Studies the sea surface, carrying high resolution microwave sensors, providing day and night coverage of weather.

  16. POLARIMETRIC MICROWAVE RADIOMETER CALIBRATION

    E-print Network

    Sarabandi, Kamal

    POLARIMETRIC MICROWAVE RADIOMETER CALIBRATION by Jinzheng Peng A dissertation submitted in partial Radiometer 16 1.5 Error in the Measurement 22 1.6 Radiometer Calibration 31 1.7 Research Objectives and Dissertation Organization 37 IV #12;Chapter 2 Statistics of Radiometer Measurements 40 2.1 Noise Variance

  17. Cosmic Microwave Background Anisotropies

    Microsoft Academic Search

    Wayne Hu; Scott Dodelson

    2002-01-01

    Cosmic microwave background (CMB) temperature anisotropies have and will continue to revolutionize our understanding of cosmology. The recent discovery of the previously predicted acoustic peaks in the power spectrum has established a working cosmological model: a critical density universe consisting of mainly dark matter and dark energy, which formed its structure through gravitational instability from quantum fluctuations during an inflationary

  18. UNIVERSAL MICROWAVE MOISTURE SENSOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sensing moisture content in granular materials accurately and in real time is of prime importance in many industries, including food and agricultural, pharmaceutical, and mining. Microwave dielectric-based sensors have been used for on-line monitoring and control of moisture content. They have the...

  19. Leakage of Microwave Ovens

    ERIC Educational Resources Information Center

    Abdul-Razzaq, W.; Bushey, R.; Winn, G.

    2011-01-01

    Physics is essential for students who want to succeed in science and engineering. Excitement and interest in the content matter contribute to enhancing this success. We have developed a laboratory experiment that takes advantage of microwave ovens to demonstrate important physical concepts and increase interest in physics. This experiment…

  20. Cosmic microwave background radiation

    Microsoft Academic Search

    Lyman Page; David Wilkinson

    1999-01-01

    The cosmic microwave background radiation (CMBR) is widely interpreted as the thermal afterglow of a hot big bang. Measurements of the CMBR intensity as a function of frequency constrain the history of cosmic energetics. Measurements of the anisotropy in the CMBR temperature provide a snapshot of the distribution of fluctuations in the gravitational potential at the earliest stages of cosmic

  1. Big Bang Leftovers in the Microwave: Cosmology with the Cosmic Microwave Background Radiation

    E-print Network

    Eric Gawiser

    2000-05-17

    We combine detections of anisotropy in the Cosmic Microwave Background radiation with observations of inhomogeneity in the large-scale distribution of galaxies to test the predictions of models of cosmological structure formation. This combination probes spatial scales varying by three orders of magnitude, including a significant region where the two types of data overlap. We examine Cold Dark Matter models with adiabatic density perturbations, isocurvature models, and a topological defects model. We set upper limits on the neutrino mass and find the primordial power spectrum needed to reconcile an apparent disagreement between structure formation observations and direct observations of cosmological parameters. Present and future observations of Cosmic Microwave Background anisotropy suffer from foreground contamination. We develop detailed predictions for microwave emission from radio and infrared-bright galaxies and the Sunyaev-Zeldovich effect from clusters. We present realistic simulations of the microwave sky, produced as part of the `WOMBAT Challenge' exercise, and introduce a pixel-space method for subtracting foreground contamination which can be tested on these simulations.

  2. Estimation of global snow cover using passive microwave data

    NASA Astrophysics Data System (ADS)

    Chang, Alfred T. C.; Kelly, Richard E.; Foster, James L.; Hall, Dorothy K.

    2003-04-01

    This paper describes an approach to estimate global snow cover using satellite passive microwave data. Snow cover is detected using the high frequency scattering signal from natural microwave radiation, which is observed by passive microwave instruments. Developed for the retrieval of global snow depth and snow water equivalent using Advanced Microwave Scanning Radiometer EOS (AMSR-E), the algorithm uses passive microwave radiation along with a microwave emission model and a snow grain growth model to estimate snow depth. The microwave emission model is based on the Dense Media Radiative Transfer (DMRT) model that uses the quasi-crystalline approach and sticky particle theory to predict the brightness temperature from a single layered snowpack. The grain growth model is a generic single layer model based on an empirical approach to predict snow grain size evolution with time. Gridding to the 25 km EASE-grid projection, a daily record of Special Sensor Microwave Imager (SSM/I) snow depth estimates was generated for December 2000 to March 2001. The estimates are tested using ground measurements from two continental-scale river catchments (Nelson River and the Ob River in Russia). This regional-scale testing of the algorithm shows that for passive microwave estimates, the average daily snow depth retrieval standard error between estimated and measured snow depths ranges from 0 cm to 40 cm of point observations. Bias characteristics are different for each basin. A fraction of the error is related to uncertainties about the grain growth initialization states and uncertainties about grain size changes through the winter season that directly affect the parameterization of the snow depth estimation in the DMRT model. Also, the algorithm does not include a correction for forest cover and this effect is clearly observed in the retrieval. Finally, error is also related to scale differences between in situ ground measurements and area-integrated satellite estimates. With AMSR-E data, improvements to snow depth and water equivalent estimates are expected since AMSR-E will have twice the spatial resolution of the SSM/I and will be able to characterize better the subnivean snow environment from an expanded range of microwave frequencies.

  3. Bayesian Analysis of the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Jewell, Jeffrey

    2007-01-01

    There is a wealth of cosmological information encoded in the spatial power spectrum of temperature anisotropies of the cosmic microwave background! Experiments designed to map the microwave sky are returning a flood of data (time streams of instrument response as a beam is swept over the sky) at several different frequencies (from 30 to 900 GHz), all with different resolutions and noise properties. The resulting analysis challenge is to estimate, and quantify our uncertainty in, the spatial power spectrum of the cosmic microwave background given the complexities of "missing data", foreground emission, and complicated instrumental noise. Bayesian formulation of this problem allows consistent treatment of many complexities including complicated instrumental noise and foregrounds, and can be numerically implemented with Gibbs sampling. Gibbs sampling has now been validated as an efficient, statistically exact, and practically useful method for low-resolution (as demonstrated on WMAP 1 and 3 year temperature and polarization data). Continuing development for Planck - the goal is to exploit the unique capabilities of Gibbs sampling to directly propagate uncertainties in both foreground and instrument models to total uncertainty in cosmological parameters.

  4. Great microwave bursts and hard X-rays from solar flares

    NASA Technical Reports Server (NTRS)

    Wiehl, H. J.; Batchelor, D. A.; Crannell, C. J.; Dennis, B. R.; Price, P. N.

    1983-01-01

    The microwave and hard X-ray charateristics of 13 solar flares that produced microwave fluxes greater than 500 Solar Flux Units were analyzed. These Great Microwave Bursts were observed in the frequency range from 3 to 35 GHz at Berne, and simultaneous hard X-ray observations were made in the energy range from 30 to 500 keV with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission spacecraft. The principal aim of this analysis is to determine whether or not the same distribution of energetic electrons can explain both emissions. Correlations were found between respective temporal characteristics and, for the first time, between microwave and hard X-ray spectral characteristics. A single-temperature and a multi-temperature model from the literature were tested for consistency with the coincident X-ray and microwave spectra at microwave burst maximum. Four events are inconsistent with both of the models tested, and neither of the models attempts to explain the high-frequency part of the microwave spectrum. A model in which the emissions above and below the peak frequency originate in two different parts of a diverging magnetic loop is proposed. With this model the entire microwave spectrum of all but one of the events is explained.

  5. Correlation between galactic HI and the Cosmic Microwave Background

    E-print Network

    Kate Land; Anze Slosar

    2007-08-31

    We revisit the issue of a correlation between the atomic hydrogen gas in our local Galaxy and the Cosmic Microwave Background (CMB), a detection of which has been claimed in some literature. We cross-correlate the 21-cm emission of Galactic atomic hydrogen as traced by the Leiden/Argentine/Bonn Galactic HI survey with the 3-year CMB data from the Wilkinson Microwave Anisotropy Probe. We consider a number of angular scales, masks, and HI velocity slices and find no statistically significant correlation.

  6. Non-Prefered Reference Frames and Anomalous Earth Flybys

    E-print Network

    Walter Petry

    2010-05-03

    Let us consider a reference frame Sigma prime in which the pseudo-Euclidean geometry holds. Einstein assumed that the principle of special relativity is valid, i.e. the reference frame of any uniformly moving observer is also described by the pseudo-Euclidean geometry. The transformation formulae from one reference frame to the other one are therefore given by the well-known Lorentz-transformations. But Einsteins assumption contradicts the observed dipole anisotropy of the cosmic microwave background (CMB) in the universe. The transformation formulae of the prefered reference frame Sigma prime in which the pseudo-Euclidean geometry is valid to a uniformly moving observer in a non-prefered reference frame Sigma are stated. The geomerty in Sigma is anisotropic. The Doppler shift of objects moving in a non-prefered reference frame is calculated. This result is applied to spacecrafts which fly near the Earth. The observed anomalous frequency shift of several spacecrafts during near Earth flybys does not arise in the non-prefered reference frame Sigma

  7. ON THE ANOMALOUS STRUCTURES OF THE VECTOR LEPTONIC CURRENTS

    E-print Network

    Rasulkhozha S. Sharafiddinov

    2003-01-01

    Each of existing types of the electric charges come forwards in the system as the source of a kind of the dipole moment. Therefore, to investigate these regularities we have established the compound structures of Dirac and Pauli form factors. They state that the electron possesses as well as the anomalous electric charge. 1 Owing to the vector nature of virtual photon, the elastic scattering of electrons by spinless nuclei depends on the Dirac F1e(q 2) and Pauli F2e(q 2) form factors of light leptons [1]. They are of course the functions of the square of four- dimentional momentum transfer. However, in spite of large number of works dedicated to the interaction between the electron and field of emission, thus far remains many uncertainties both in the structures and in the behavior of these currents. Usually it is accepted that F2e(0) is equal to the electron anomalous magnetic moment [2], and its full magnetic moment is defined by the combination [3] of form factors [4] µ full

  8. Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Alves, M. I. R.; Aniano, G.; Armitage-Caplan, C.; Arnaud, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Ganga, K.; Ghosh, T.; Giard, M.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Magalhães, A. M.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Noviello, F.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Rachen, J. P.; Reach, W. T.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Salerno, E.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wandelt, B. D.; Zacchei, A.; Zonca, A.

    2015-04-01

    Planck has mapped the intensity and polarization of the sky at microwave frequencies with unprecedented sensitivity. We use these data to characterize the frequency dependence of dust emission. We make use of the Planck 353 GHz I, Q, and U Stokes maps as dust templates, and cross-correlate them with the Planck and WMAP data at 12 frequencies from 23 to 353 GHz, over circular patches with 10° radius. The cross-correlation analysis is performed for both intensity and polarization data in a consistent manner. The results are corrected for the chance correlation between the templates and the anisotropies of the cosmic microwave background. We use a mask that focuses our analysis on the diffuse interstellar medium at intermediate Galactic latitudes. We determine the spectral indices of dust emission in intensity and polarization between 100 and 353 GHz, for each sky patch. Both indices are found to be remarkably constant over the sky. The mean values, 1.59 ± 0.02 for polarization and 1.51 ± 0.01 for intensity, for a mean dust temperature of 19.6 K, are close, but significantly different (3.6?). We determine the mean spectral energy distribution (SED) of the microwave emission, correlated with the 353 GHz dust templates, by averaging the results of the correlation over all sky patches. We find that the mean SED increases for decreasing frequencies at ?< 60 GHz for both intensity and polarization. The rise of the polarization SED towards low frequencies may be accounted for by a synchrotron component correlated with dust, with no need for any polarization of the anomalous microwave emission. We use a spectral model to separate the synchrotron and dust polarization and to characterize the spectral dependence of the dust polarization fraction. The polarization fraction (p) of the dust emission decreases by (21 ± 6)% from 353 to 70 GHz. We discuss this result within the context of existing dust models. The decrease in p could indicate differences in polarization efficiency among components of interstellar dust (e.g., carbon versus silicate grains). Our observational results provide inputs to quantify and optimize the separation between Galactic and cosmological polarization. Appendices are available in electronic form at http://www.aanda.org

  9. Demonstration of ocean surface salinity microwave measurements from space using AMSR-E data over the Amazon plume

    Microsoft Academic Search

    N. Reul; S. Saux-Picart; B. Chapron; D. Vandemark; J. Tournadre; J. Salisbury

    2009-01-01

    Microwave Sea Surface Salinity (SSS) measurements can be performed by isolating the emissivity response to salinity changes from numerous geophysical effects, including surface temperature and wind waves. At L-band frequencies (1 to 2 GHz), the sensitivity to SSS is sufficient but it falls off quickly as frequency is increased. Nevertheless, methods using higher microwave frequencies with much lower SSS sensitivity

  10. Microwave Anisotrophy Probe Launch and Early Operations

    NASA Technical Reports Server (NTRS)

    ODonnell, James R., Jr.; Andrews, Stephen F.; Starin, Scott R.; Ward, David K.; Bauer, Frank H. (Technical Monitor)

    2002-01-01

    The Microwave Anisotropy Probe (MAP), a follow-on to the Differential Microwave Radiometer (DMR) instrument on the Cosmic Background Explorer (COBE), was launched from the Kennedy Space Center at 19:46:46 UTC on June 30, 2001. The powered flight and separation from the Delta II appeared to go as designed, with the launch placing MAP well within sigma launch dispersion and with less than 7 Nms of tip-off momentum. Because of this relatively low momentum, MAP was able to acquire the sun within only 15 minutes with a battery state of charge of 94%. After MAP's successful launch, a six week period of in-orbit checkout and orbit maneuvers followed. The dual purpose of the in-orbit checkout period was to validate the correct performance of all of MAP's systems and, from the attitude control system (ACS) point of view, to calibrate the performance of the spacecraft ACS sensors and actuators to maximize system performance. In addition to the checkout activities performed by the MAP team, the other critical activity taking place during the first six weeks after launch were a series of orbit maneuvers necessary to get the spacecraft from its launch orbit out to its desired orbit about L2, the second Earth-Sun Lagrange point. As MAP continues its standard operations, its ACS design is meeting all of its requirements to successfully complete the mission. This paper will describe the launch and early operations summarized above in greater detail, and show the performance of the attitude control and attitude determination system versus its requirements. Additionally, some of the unexpected events that occurred during this period will be discussed, including two events which dropped the spacecraft into its Safehold Mode and the presence of an "anomalous force" observed during each of the perigee orbit maneuvers that had the potential to cause these critical maneuvers to be prematurely aborted.

  11. Foundations for statistical-physical precipitation retrieval from passive microwave satellite measurements. II - Emission-source and generalized weighting-function properties of a time-dependent cloud-radiation model

    NASA Technical Reports Server (NTRS)

    Mugnai, Alberto; Smith, Eric A.; Tripoli, Gregory J.

    1993-01-01

    The foremost physical aspects of microphysical-radiative interactions that control the formation and modulation of frequency-dependent passive microwave TB over a continental cold-rain precipitation system are explained within the framework of the essential ingredients of a physically based precipitation-retrieval algorithm. The analysis is based on a modeling study in which a 3D cloud model has provided the objective basis for generating an extensive set of microphysical profiles that describe numerous precipitation features in the course of the evolution of a continental hail storm. A summary of the various components of the algorithm, as well as the surface rain rates, is given. The algorithm employs the cloud model to provide a consistent and objectively generated source of detailed microphysical information as the underpinnings to an inversion-based perturbative retrieval scheme.

  12. Microwave Brightness Temperatures of Tilted Convective Systems

    NASA Technical Reports Server (NTRS)

    Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

    1998-01-01

    Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

  13. Wilkinson Microwave Anisotropy Probe

    NSDL National Science Digital Library

    1969-12-31

    NASA's Wilkinson Microwave Anisotropy Probe mission attempts to reveal conditions as they existed in the early universe by measuring the properties of the cosmic microwave background radiation over the full sky. Visitors can learn more about the particulars of the mission, explore the subjects of cosmology and the "Big Bang Theory" on the Universe link, view images of the probe and its launch in June 2001, and study the first detailed full-sky map of the oldest light in the universe. Although it may not seem it at first, this site contains a lot of material to browse, including an attempt in the FAQ section to answer whether or not there is there a conflict between science and religion.

  14. Transscleral microwave cyclodestruction

    SciTech Connect

    Finger, P.T.; Smith, P.D.; Paglione, R.W.; Perry, H.D. (North Shore Univ. Hospital-Cornell Univ. Medical College, Manhasset, NY (USA))

    1990-10-01

    A 4.6-gigahertz (GHz) microwave applicator was used to ablate the ciliary body in rabbit eyes. High-frequency electromagnetic radiation provides a favorable dose distribution to induce local heating of the ciliary body. For treatment, a 3-mm diameter disc-shaped applicator was placed on the conjunctiva and over the ciliary body. Conjunctival temperatures were monitored during treatment with a built-in thermocouple thermometer located at the center of the disc-shaped antenna. This allowed direct measurement (dosimetry) of the conjunctival temperature during treatment. Using this microwave-based heat-delivery system, doses in a range of 60 degrees for 30 or 60 seconds appeared to cause ciliary body damage with relative sparing of the conjunctiva and sclera.

  15. P-type electrical, photoconductive, and anomalous ferromagnetic properties of Cu2O nanowires

    Microsoft Academic Search

    L. Liao; B. Yan; Y. F. Hao; G. Z. Xing; J. P. Liu; B. C. Zhao; Z. X. Shen; T. Wu; L. Wang; J. T. L. Thong; C. M. Li; W. Huang; T. Yu

    2009-01-01

    Cu2O nanowires are synthesized by reduction of CuO nanowires with hydrogen gas. Strong green photoluminescence dominated by band-edge emission is observed. Field effect transistors fabricated from individual Cu2O nanowires present high on-off ratio (>106) and high mobility (>95 cm2\\/V s). Furthermore, the device demonstrates a fast photoelectric response to blue illumination in air at room temperature. In addition, anomalous ferromagnetism

  16. ON THE SOURCE OF ASTROMETRIC ANOMALOUS REFRACTION

    SciTech Connect

    Taylor, M. Suzanne [Department of Natural and Environmental Sciences, Western State Colorado University, 128 Hurst Hall, Gunnison, CO 81230 (United States); McGraw, John T.; Zimmer, Peter C. [Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131 (United States); Pier, Jeffrey R., E-mail: mstaylor@western.edu [Division of Astronomical Sciences, NSF 4201 Wilson Blvd, Arlington, VA 22230 (United States)

    2013-03-15

    More than a century ago, astronomers using transit telescopes to determine precise stellar positions were hampered by an unexplained periodic shifting of the stars they were observing. With the advent of CCD transit telescopes in the past three decades, this unexplained motion, termed 'anomalous refraction' by these early astronomers, is again being observed. Anomalous refraction is described as a low-frequency, large angular scale ({approx}2 Degree-Sign ) motion of the entire image plane with respect to the celestial coordinate system as observed and defined by astrometric catalogs. These motions, of typically several tenths of an arcsecond amplitude with timescales on the order of 10 minutes, are ubiquitous to ground-based drift-scan astrometric measurements regardless of location or telescopes used and have been attributed to the effect of tilting of equal-density layers of the atmosphere. The cause of this tilting has often been attributed to atmospheric gravity waves, but this cause has never been confirmed. Although theoretical models of atmospheric refraction show that atmospheric gravity waves are a plausible cause of anomalous refraction, an observational campaign specifically directed at defining this relationship provides clear evidence that anomalous refraction is not consistent with the passage of atmospheric gravity waves. The source of anomalous refraction is found to be meter-scale, slowly evolving quasi-coherent dynamical structures in the boundary layer below 60 m above ground level.

  17. Parametric probability distributions for anomalous change detection

    SciTech Connect

    Theiler, James P [Los Alamos National Laboratory; Foy, Bernard R [Los Alamos National Laboratory; Wohlberg, Brendt E [Los Alamos National Laboratory; Scovel, James C [Los Alamos National Laboratory

    2010-01-01

    The problem of anomalous change detection arises when two (or possibly more) images are taken of the same scene, but at different times. The aim is to discount the 'pervasive differences' that occur thoughout the imagery, due to the inevitably different conditions under which the images were taken (caused, for instance, by differences in illumination, atmospheric conditions, sensor calibration, or misregistration), and to focus instead on the 'anomalous changes' that actually take place in the scene. In general, anomalous change detection algorithms attempt to model these normal or pervasive differences, based on data taken directly from the imagery, and then identify as anomalous those pixels for which the model does not hold. For many algorithms, these models are expressed in terms of probability distributions, and there is a class of such algorithms that assume the distributions are Gaussian. By considering a broader class of distributions, however, a new class of anomalous change detection algorithms can be developed. We consider several parametric families of such distributions, derive the associated change detection algorithms, and compare the performance with standard algorithms that are based on Gaussian distributions. We find that it is often possible to significantly outperform these standard algorithms, even using relatively simple non-Gaussian models.

  18. Analytical solutions for anomalous dispersion transport

    NASA Astrophysics Data System (ADS)

    O'Malley, D.; Vesselinov, V. V.

    2014-06-01

    Groundwater flow and transport often occur in a highly heterogeneous environment (potentially heterogeneous at multiple spatial scales) and is impacted by geochemical reactions, advection, diffusion, and other pore scale processes. All these factors can give rise to large-scale anomalous dispersive behavior that can make complex model representation and prediction of plume concentrations challenging due to difficulties unraveling all the complexities associated with the governing processes, flow medium, and their parameters. An alternative is to use upscaled stochastic models of anomalous dispersion, and this is the approach used here. Within a probabilistic framework, we derive a number of analytical solutions for several anomalous dispersion models. The anomalous dispersion models are allowed to be either non-Gaussian (?-stable Lévy), correlated, or nonstationary from the Lagrangian perspective. A global sensitivity analysis is performed to gain a greater understanding of the extent to which uncertainty in the parameters associated with the anomalous behavior can be narrowed by examining concentration measurements from a network of monitoring wells and to demonstrate the computational speed of the solutions. The developed analytical solutions are encoded and available for use in the open source computational framework MADS (http://mads.lanl.gov).

  19. Anomalous scalings in differential models of turbulence

    E-print Network

    Simon Thalabard; Sergey Nazarenko; Sebastien Galtier; Medvedev Sergey

    2015-02-24

    Differential models for hydrodynamic, passive-scalar and wave turbulence given by nonlinear first- and second-order evolution equations for the energy spectrum in the $k$-space were analysed. Both types of models predict formation an anomalous transient power-law spectra. The second-order models were analysed in terms of self-similar solutions of the second kind, and a phenomenological formula for the anomalous spectrum exponent was constructed using numerics for a broad range of parameters covering all known physical examples. The first-order models were examined analytically, including finding an analytical prediction for the anomalous exponent of the transient spectrum and description of formation of the Kolmogorov-type spectrum as a reflection wave from the dissipative scale back into the inertial range. The latter behaviour was linked to pre-shock/shock singularities similar to the ones arising in the Burgers equation. Existence of the transient anomalous scaling and the reflection-wave scenario are argued to be a robust feature common to the finite-capacity turbulence systems. The anomalous exponent is independent of the initial conditions but varies for for different models of the same physical system.

  20. The cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1989-01-01

    Recent observational and theoretical investigations of the cosmic microwave background radiation (CMBR) are reviewed. Particular attention is given to spectral distortions and CMBR temperature anisotropies at large, intermediate, and small angular scales. The implications of the observations for inflationary cosmological models with curvature fluctuation are explored, and it is shown that the limits determined for intermediate-scale CMBR anisotropy almost rule out a baryon-dominated cosmology.

  1. Microwave blackbodies for spaceborne receivers

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.

    1985-01-01

    The properties of microwave blackbody targets are explained as they apply to the calibration of spaceborne receivers. Also described are several practicable, blackbody targets used to test and calibrate receivers in the laboratory and in the thermal vacuum chamber. Problems with the precision and the accuracy of blackbody targets, and blackbody target design concepts that overcome some of the accuracy limitations present in existing target designs, are presented. The principle of the Brewster angle blackbody target is described where the blackbody is applied as a fixed-temperature test target in the laboratory and as a variable-temperature target in the thermal vacuum chamber. The reflectivity of a Brewster angle target is measured in the laboratory. From this measurement, the emissivity of the target is calculated. Radiatively cooled thermal suspensions are discussed as the coolants of blackbody targets and waveguide terminations that function as calibration devices in spaceborne receivers. Examples are given for the design of radiatively cooled thermal suspensions. Corrugated-horn antennas used to observe the cosmic background and to provide a cold-calibration source for spaceborne receivers are described.

  2. INFRARED EMISSION SPECTROSCOPY OF HOT CARBON FARNOOD KHALILZADEH REZAIE

    E-print Network

    Peale, Robert E.

    temperature emission spectra of CO obtained from a microwave discharge plasma, where the source of CO was carbon dioxide that dissociates under microwave heating. The spectrum was measured in the range 1800 within the rotational fine structure, we obtain a temperature estimate of ~700 K, which is comparable

  3. New microwave coupler material

    SciTech Connect

    Holcombe, C.E.

    1983-12-01

    The unexpected coupling of urania (UO/sub x/, with 2 less than or equal to x less than or equal to 3) to microwave energy has previously been reported. The present study screened several different materials for coupling with microwave energy using a 1.6 kW, 2450 MHz system. Materials were nominally -100 mesh powder, >99% pure. Those which showed minimal or no heating with the microwave energy included Y/sub 2/O/sub 3/, Al/sub 2/O/sub 3/, SiO/sub 2/, BN, graphite, and unstabilized ZrO/sub 2/. Pronounced heating occurred with B/sub 4/C. This discovery led to the following evaluation/comparison of the coupling ability of B/sub 4/C with water, structurally similar materials (boron suboxide, B/sub 6/O - prepared from zinc oxide and boron, microcrystalline or amorphous boron, ..cap alpha..-type), and UO/sub 2/. In order to compare relative heating rates, the materials were placed into 50 mL beakers, covered with alumina-silica felt insulation, and subjected to 30 s at full power (both top and bottom sources on). The temperature was measured at the end of the test, after the door automatically opened, by inserting a type K thermocouple into the material. For the powders, the thermocouple was moved about to obtain the highest reading, although only a 10% or so variation occurred before the temperature dropped from heat losses. 4 references, 1 table.

  4. Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior

    NASA Astrophysics Data System (ADS)

    Klem, B.; Swann, D.

    2011-09-01

    Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection from both the sun and the underlying earth surface. The objects are modeled to be either tumbling or spin stabilized at key orientations in order to capture the complexity of the solar/earth incident illumination and the sensor viewing aspect conditions. Although these geometries and processes appear to be specialized and limited, they are sufficient to capture the principal observable features that are necessary for gaining insight into the complex issues of interpreting non-imaging sensor signals for monitoring the actual on-orbit spacecraft behavior changes. This talk has been prepared as a poster paper, to allow for engagement with conference participants on the presentation contents, and discussions for expansion of the material to include additional topical areas for future work, as appropriate. All discussions have been limited only to topics that could be discussed in the open format of the conference.

  5. Theory for passive microwave remote sensing of near-surface soil moisture

    Microsoft Academic Search

    Eni G. Njoku; Jin-Au Kong

    1977-01-01

    The theory of microwave thermal emission from a nonscattering half-space medium is developed for application to regions with nonuniform subsurface soil moisture and temperature variations. A coherent stratified model is presented which is valid for nonuniform temperature profiles and rapidly varying moisture profiles, under which conditions the commonly used emissivity and radiative transfer approaches become inaccurate. For naturally occurring profiles

  6. Self-assembly of carbon nanohelices: Characteristics and field electron emission properties

    E-print Network

    Zhang, Guangyu

    Self-assembly of carbon nanohelices: Characteristics and field electron emission properties Guangyu. Their field-emission properties were investigated. Carbon nanohelices were fabricated using microwave- plasma of self-assembled carbon nanohelices on iron needles using microwave plasma assisted chemical vapor

  7. Microwave Preparation of Oxide Bronzes

    NASA Astrophysics Data System (ADS)

    Rao, K. J.; Ramakrishnan, P. A.; Gadagkar, Rohit

    1999-11-01

    Several vanadium, tungsten, and molybdenum oxide bronzes have been prepared using microwave irradiation. Metal oxides and alkali metal iodides were used as starting materials. Intermittent grinding and inert atmosphere were found to be necessary for the synthesis of most of the bronzes. The reaction temperatures are remarkably lower than those employed for conventional synthetic techniques and the microwave assisted reactions proceed at extremely fast rates. The microwave synthesized bronzes consist of particles having long, rectangular rod-like morphology.

  8. Satellite microwave observations of the Utah Great Salt Lake Desert

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dellwig, L. F.; Schmugge, T. J.

    1975-01-01

    Microwave data acquired over the Great Salt Lake Desert by sensors aboard Skylab and Nimbus 5 indicate that microwave emission and backscatter were strongly influenced by contributions from subsurface layers of sediment saturated with brine. This phenomenon was observed by Skylab's S-194 radiometer operating at 1.4 GHz, S-193 RADSCAT (Radiometer-Scatterometer) operating at 13.9 GHz and the Nimbus 5 ESMR (Electrically Scanning Microwave Radiometer) operating at 19.35 GHz. The availability of ESMR data over an 18 month period allowed an investigation of temporal variations. Aircraft 1.4 GHz radiometer data acquired two days after one of the Skylab passes confirm the satellites observations. Data from the ESMR revealed similar responses over the Bolivian deserts, which have geologic features similar to those of the Utah desert.

  9. Airborne microwave radiometer remote sensing of lake ice

    NASA Technical Reports Server (NTRS)

    Swift, C. T.; Harrington, R. F.; Thornton, H. F.

    1980-01-01

    The NASA Langley C-Band Stepped Frequency Microwave Radiometer was used to conduct airborne remote sensing measurements of the Great Lakes ice cover during the winters of 1978 and 1979. In order to evaluate the use of microwave radiometry for remote sensing of fresh water ice, an initial experiment was conducted in February 1978. After the results were analyzed an algorithm was developed, and a more comprehensive mission was completed in March 1979, which related the thermal emission from lake ice to meaningful geophysical quantities. A clear discrimination of pressure ridges and rubble from base ice was observed, and evidence was found which showed gradual changes in the thickness of the base itself. Results indicate that passive microwave sensors can provide a measure of lake ice within uncertainties presented by the attenuation coefficient, and the changes in surface reflectivity imposed by surface roughness.

  10. Anomalous biceps origin from the rotator cuff

    PubMed Central

    Banerjee, Samik; Patel, Vipul R

    2015-01-01

    Variations in the origin of the long head of biceps tendon (LHBT) have been described in literature; however, its clinical significance remains uncertain. We describe in this report, the history, physical examination and the arthroscopic findings in a patient who had an anomalous origin of the LHBT from the rotator cuff, resulting in restriction of range of motion. This anomalous origin of the long head of biceps tendon causing capsular contracture and restriction of movements leading to secondary internal impingement, has not been extensively reported in the literature. Shoulder arthroscopists should be aware that, although, an uncommon clinical condition, the aberrant congenital origin of the LHBT from the rotator cuff can rarely become pathologic in middle age and lead to shoulder dysfunction. In such cases, release of the anomalous band may be required, along with the treatment of other concomitant intraarticular pathologies in the glenohumeral joint. PMID:25593361

  11. Investigation of anomalous grains in polynanocrystalline nickel

    NASA Astrophysics Data System (ADS)

    Darnbrough, J. E.; Mahalingam, S.; Flewitt, P. E. J.

    2012-07-01

    Polynanocrystalline nickel, with an as received grain size distribution in the range 30 to 80 nm, when heat treated at a temperature of 500°C causes overall coarsening of the grains and anomalous growth of some grains. This leads to a bimodal grain size distribution. The anomalous large grains, typically 75-100 ? m, have an angular morphology that is not typical of the polyhedral grains within the overall distribution. Using a combination of focus ion beam milling and imaging, and electron backscatter diffraction it has been established that the interfacial planes forming the overall grain boundaries for these anomalous large grains include 110, 210, 112 and 310 planes. In addition a substructure is produced within the large grains interrelated in size with the subsumed nano-scale grains. The results are discussed briefly with respect to the more energetically favourable 111 boundary planes and the overall mobility.

  12. Time-space fabric underlying anomalous diffusion

    E-print Network

    W Chen

    2005-05-08

    This study unveils the time-space transforms underlying anomalous diffusion process. Based on this finding, we present the two hypotheses concerning the effect of fractal time-space fabric on physical behaviors and accordingly derive fractional quantum relationships between energy and frequency, momentum and wavenumber which further give rise to fractional Schrodinger equation. As an alternative modeling approach to the standard fractional derivatives, we introduce the concept of the Hausdorff derivative underlying the Hausdorff dimensions of metric spacetime. And in terms of the proposed hypotheses, the Hausdorff derivative is used to derive a linear anomalous transport-diffusion equation underlying anomalous diffusion process. Its Green's function solution turns out to be a new type of stretched Gaussian distribution and is compared with that from the Richardson's diffusion equation.

  13. Anomalous biceps origin from the rotator cuff.

    PubMed

    Banerjee, Samik; Patel, Vipul R

    2015-01-01

    Variations in the origin of the long head of biceps tendon (LHBT) have been described in literature; however, its clinical significance remains uncertain. We describe in this report, the history, physical examination and the arthroscopic findings in a patient who had an anomalous origin of the LHBT from the rotator cuff, resulting in restriction of range of motion. This anomalous origin of the long head of biceps tendon causing capsular contracture and restriction of movements leading to secondary internal impingement, has not been extensively reported in the literature. Shoulder arthroscopists should be aware that, although, an uncommon clinical condition, the aberrant congenital origin of the LHBT from the rotator cuff can rarely become pathologic in middle age and lead to shoulder dysfunction. In such cases, release of the anomalous band may be required, along with the treatment of other concomitant intraarticular pathologies in the glenohumeral joint. PMID:25593361

  14. Si3N4 ring resonator-based microwave photonic notch filter with an ultrahigh peak rejection

    E-print Network

    Marpaung, David; Pant, Ravi; Roeloffzen, Chris; Leinse, Arne; Hoekman, Marcel; Heideman, Rene; Eggleton, Benjamin J

    2013-01-01

    We report a simple technique in microwave photonic (MWP) signal processing that allows the use of an optical filter with a shallow notch to exhibit a microwave notch filter with anomalously high rejection level. We implement this technique using a low-loss, tunable Si3N4 optical ring resonator as the optical filter, and achieved an MWP notch filter with an ultra-high peak rejection > 60 dB, a tunable high resolution bandwidth of 247-840 MHz, and notch frequency tuning of 2-8 GHz. To our knowledge, this is a record combined peak rejection and resolution for an integrated MWP filter.

  15. The Microwave SQUID Multiplexer

    NASA Astrophysics Data System (ADS)

    Mates, John Arthur Benson

    2011-12-01

    This thesis describes a multiplexer of Superconducting Quantum Interference Devices (SQUIDs) with low-noise, ultra-low power dissipation, and great scalability. The multiplexer circuit measures the magnetic flux in a large number of unshunted rf SQUIDs by coupling each SQUID to a superconducting microwave resonator tuned to a unique resonance frequency and driving the resonators from a common feedline. A superposition of microwave tones measures each SQUID simultaneously using only two coaxial cables between the cryogenic device and room temperature. This multiplexer will enable the instrumentation of arrays with hundreds of thousands of low-temperature detectors for new applications in cosmology, materials analysis, and nuclear non-proliferation. The driving application of the Microwave SQUID Multiplexer is the readout of large arrays of superconducting transition-edge sensors, by some figures of merit the most sensitive detectors of electromagnetic signals over a span of more than nine orders of magnitude in energy, from 40 GHz microwaves to 200 keV gamma rays. Modern transition-edge sensors have noise-equivalent power as low as 10-20 W / Hz1/2 and energy resolution as good as 2 eV at 6 keV. These per-pixel sensitivities approach theoretical limits set by the underlying signals, motivating a rapid increase in pixel count to access new science. Compelling applications, like the non-destructive assay of nuclear material for treaty verification or the search for primordial gravity waves from inflation use arrays of these detectors to increase collection area or tile a focal plane. We developed three generations of SQUID multiplexers, optimizing the first for flux noise 0.17 muPhi0 / Hz1/2, the second for input current noise 19 pA / Hz1/2, and the last for practical multiplexing of large arrays of cosmic microwave background polarimeters based on transition-edge sensors. Using the last design we demonstrated multiplexed readout of prototype polarimeters with the performance required for the future development of a large-scale astronomical instrument.

  16. Microwave-Assisted Ignition for Improved Internal Combustion Engine Efficiency

    NASA Astrophysics Data System (ADS)

    DeFilippo, Anthony Cesar

    The ever-present need for reducing greenhouse gas emissions associated with transportation motivates this investigation of a novel ignition technology for internal combustion engine applications. Advanced engines can achieve higher efficiencies and reduced emissions by operating in regimes with diluted fuel-air mixtures and higher compression ratios, but the range of stable engine operation is constrained by combustion initiation and flame propagation when dilution levels are high. An advanced ignition technology that reliably extends the operating range of internal combustion engines will aid practical implementation of the next generation of high-efficiency engines. This dissertation contributes to next-generation ignition technology advancement by experimentally analyzing a prototype technology as well as developing a numerical model for the chemical processes governing microwave-assisted ignition. The microwave-assisted spark plug under development by Imagineering, Inc. of Japan has previously been shown to expand the stable operating range of gasoline-fueled engines through plasma-assisted combustion, but the factors limiting its operation were not well characterized. The present experimental study has two main goals. The first goal is to investigate the capability of the microwave-assisted spark plug towards expanding the stable operating range of wet-ethanol-fueled engines. The stability range is investigated by examining the coefficient of variation of indicated mean effective pressure as a metric for instability, and indicated specific ethanol consumption as a metric for efficiency. The second goal is to examine the factors affecting the extent to which microwaves enhance ignition processes. The factors impacting microwave enhancement of ignition processes are individually examined, using flame development behavior as a key metric in determining microwave effectiveness. Further development of practical combustion applications implementing microwave-assisted spark technology will benefit from predictive models which include the plasma processes governing the observed combustion enhancement. This dissertation documents the development of a chemical kinetic mechanism for the plasma-assisted combustion processes relevant to microwave-assisted spark ignition. The mechanism includes an existing mechanism for gas-phase methane oxidation, supplemented with electron impact reactions, cation and anion chemical reactions, and reactions involving vibrationally-excited and electronically-excited species. Calculations using the presently-developed numerical model explain experimentally-observed trends, highlighting the relative importance of pressure, temperature, and mixture composition in determining the effectiveness of microwave-assisted ignition enhancement.

  17. Multiphoton processes at cyclotron resonance subharmonics in a two-dimensional electron system under dc and microwave excitation

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Hatke, A. T.; Engel, L. W.; Watson, J. D.; Manfra, M. J.

    2014-11-01

    We investigate a two-dimensional electron system (2DES) under microwave illumination at cyclotron resonance subharmonics. The 2DES carries sufficient direct current, I , that the differential resistivity oscillates as I is swept. At magnetic fields sufficient to resolve individual Landau levels, we find the number of oscillations within an I range systematically changes with increasing microwave power. Microwave absorption and emission of N photons, where N is controlled by the microwave power, describes our observations in the framework of the displacement mechanism of impurity scattering between Hall-field tilted Landau levels.

  18. A Flat Universe from High-Resolution Maps of the Cosmic MicrowaveBackground Radiation

    SciTech Connect

    de Bernardis, P.; Ade, P.A.R.; Bock, J.J.; Bond, J.R.; Borrill,J.; Boscaleri, A.; Coble, K.; Crill, B.P.; De Gasperis, G.; Farese, P.C.; Ferreira, P.G.; Ganga, K.; Giacometti, M.; Hivon, E.; Hristov, V.V.; Iacoangeli, A.; Jaffe, A.H.; Lange, A.E.; Martinis, L.; Masi, S.; Mason,P.; Mauskopf, P.D.; Melchiorri, A.; Miglio, L.; Montroy, T.; Netterfield,C.B.; Pascale, E.; Piacentini, F.; Pogosyan, D.; Prunet, S.; Rao, S.; Romeo, G.; Ruhl, J.E.; Scaramuzzi, F.; Sforna, D.; Vittorio, N.

    2000-04-28

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole {ell}{sub peak} = (197 {+-} 6), with an amplitude DT{sub 200} = (69 {+-} 8){mu}K. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favored by standard inflationary scenarios.

  19. A Flat Universe from High-Resolution Maps of the Cosmic Microwave Background Radiation

    E-print Network

    P. de Bernardis; P. A. R. Ade; J. J. Bock; J. R. Bond; J. Borrill; A. Boscaleri; K. Coble; B. P. Crill; G. De Gasperis; P. C. Farese; P. G. Ferreira; K. Ganga; M. Giacometti; E. Hivon; V. V. Hristov; A. Iacoangeli; A. H. Jaffe; A. E. Lange; L. Martinis; S. Masi; P. Mason; P. D. Mauskopf; A. Melchiorri; L. Miglio; T. Montroy; C. B. Netterfield; E. Pascale; F. Piacentini; D. Pogosyan; S. Prunet; S. Rao; G. Romeo; J. E. Ruhl; F. Scaramuzzi; D. Sforna; N. Vittorio

    2000-04-28

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73K Cosmic Microwave Background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole $\\ell_{peak}=(197 \\pm 6)$, with an amplitude $DT_{200}=(69 \\pm 8)\\mu K$. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary scenarios.

  20. A flat Universe from high-resolution maps of the cosmic microwave background radiation

    PubMed

    de Bernardis P; Ade; Bock; Bond; Borrill; Boscaleri; Coble; Crill; De Gasperis G; Farese; Ferreira; Ganga; Giacometti; Hivon; Hristov; Iacoangeli; Jaffe; Lange; Martinis; Masi; Mason; Mauskopf; Melchiorri; Miglio; Montroy; Netterfield

    2000-04-27

    The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole Ipeak = (197 +/- 6), with an amplitude delta T200 = (69 +/- 8) microK. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models. PMID:10801117