Sample records for microwave anomalous emission

  1. Anomalous Microwave Emission in NGC 6946

    NASA Astrophysics Data System (ADS)

    Hensley, Brandon; Murphy, E. J.

    2013-01-01

    The dust-correlated Anomalous Microwave Emission (AME), attributed to electric dipole emission from spinning dust grains, has been observed in the Galaxy for over a decade. In 2010, Murphy et al. presented GBT observations of NGC 6946, which showed strong evidence of this emission in several extra-nuclear regions, making it the first extra-galactic detection of the AME. We present follow-up observations at 3mm and 1cm with CARMA and synthesize composite SEDs using maps from Spitzer, Herschel, GISMO, VLA, and WSRT. We confirm the detection of AME in extra-nuclear region 4 and present evidence of anomalous emission in other regions of the galaxy. We discuss the inferred properties of both the dust and the environment in these regions based upon the composite SEDs.

  2. Polarization of the Anomalous Microwave Emission

    NASA Astrophysics Data System (ADS)

    López-Caraballo, C. H.; Génova-Santos, R.

    2013-05-01

    The standard physical mechanisms of the continuum emission in the microwave range are the synchrotron, free-free, and/or thermal dust emissions. Nevertheless, and based on observations over the last two decades, we can find a new process of emission, called Anomalous Microwave Emission (AME), which consists of an excess of dust-correlated microwave emission (10-60 GHz). Observational studies of the AME, both in intensity and polarization, allowed us to extend our knowledge of the different physical processes in the Interstellar Medium (ISM), as well as its implications in the study of the inflationary epoch of the Universe, via the possible effects in the detectability of the polarization of the Cosmic Microwave Background (CMB), in particular the detection of B-modes. In this talk, we present a summary of the observational measurements of the polarization of the AME for: 1) the diffuse Galactic emission (only two works based on the WMAP data); and 2) individual Galactic regions, two H{II} regions LPH96 and Helix; and four dust clouds Perseus, ? Ophiuchi, LDN1622 and Pleiades). Around the peak of the emission (20-30 GHz), the constraints on the fractional polarization of AME are of the order of ˜1% (95% C.L.) for both individual compact and large-scale Galactic regions. Then, we use these constraints in order to test the theoretical AME models available to date. Finally, we discuss the effects of a polarized diffuse AME contribution on the current and future polarized CMB experiments.

  3. Anomalous Microwave Emission from the H II Region RCW175

    Microsoft Academic Search

    C. Dickinson; R. D. Davies; J. R. Allison; J. R. Bond; S. Casassus; K. Cleary; R. J. Davis; M. E. Jones; B. S. Mason; S. T. Myers; T. J. Pearson; A. C. S. Readhead; J. L. Sievers; A. C. Taylor; M. Todorovic; G. J. White; P. N. Wilkinson

    2009-01-01

    We present evidence for anomalous microwave emission in the RCW175 H II region. Motivated by 33 GHz 13' resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of 4'. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio.

  4. Anomalous Microwave Emission from the HII region RCW175

    Microsoft Academic Search

    C. Dickinson; R. D. Davies; J. R. Allison; J. R. Bond; S. Casassus; K. Cleary; R. J. Davis; M. E. Jones; B. S. Mason; S. T. Myers; T. J. Pearson; A. C. S. Readhead; J. L. Sievers; A. C. Taylor; M. Todorovic; G. J. White; P. N. Wilkinson

    2008-01-01

    We present evidence for anomalous microwave emission in the RCW175 \\\\hii\\u000aregion. Motivated by 33 GHz $13\\\\arcmin$ resolution data from the Very Small\\u000aArray (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager\\u000a(CBI) at a resolution of $4\\\\arcmin$. The region consists of two distinct\\u000acomponents, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise\\u000aratio. The

  5. Observations and Theory of the Anomalous Microwave Emission

    NASA Astrophysics Data System (ADS)

    Stevenson, Matthew; Readhead, A. C.; Pearson, T. J.; Cleary, K.; Tibbs, C.; Villadsen, J.; Hirata, C. M.; Paladini, R.; Muchovej, S.; Grainge, K.; Perrott, Y.; Rumsey, C.; Scaife, A.; C-BASS Collaboration

    2013-01-01

    The recently discovered Anomalous Microwave Emission (AME) presents a potential new probe of interstellar dust. Peaking at around 30GHz, having a width of several tens of GHz, and appearing to be highly dust-correlated, this continuum emission is commonly assumed to be due very small, rapidly spinning dust grains. Directed study of the AME may therefore provide a new handle on these grains and their environments. I will present three projects aimed at advancing our understanding of this emission. The first is a new, analytical derivation of radiation from spinning dust grains, bridging the gap between the precise models and realistic observations. The second is a joint CARMA/AMI survey of Planck Early Cold Clumps, searching for predicted spinning dust emission. The third is a correlation analysis of diffuse microwave emission from the North Celestial Pole, combining a new 5GHz map from the C-Band All-Sky Survey (C-BASS) with existing radio, WMAP, IRAS, and H? maps. This work was supported in part by the NSF (AST-1212217).

  6. Anomalous Microwave Emission from the HII region RCW175

    E-print Network

    C. Dickinson; R. D. Davies; J. R. Allison; J. R. Bond; S. Casassus; K. Cleary; R. J. Davis; M. E. Jones; B. S. Mason; S. T. Myers; T. J. Pearson; A. C. S. Readhead; J. L. Sievers; A. C. Taylor; M. Todorovic; G. J. White; P. N. Wilkinson

    2008-07-25

    We present evidence for anomalous microwave emission in the RCW175 \\hii region. Motivated by 33 GHz $13\\arcmin$ resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of $4\\arcmin$. The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio. The integrated flux density is $5.97\\pm0.30$ Jy at 31 GHz, in good agreement with the VSA. The 31 GHz flux density is $3.28\\pm0.38$ Jy ($8.6\\sigma$) above the expected value from optically thin free-free emission based on lower frequency radio data and thermal dust constrained by IRAS and WMAP data. Conventional emission mechanisms such as optically thick emission from ultracompact \\hii regions cannot easily account for this excess. We interpret the excess as evidence for electric dipole emission from small spinning dust grains, which does provide an adequate fit to the data.

  7. Detection of Anomalous Microwave Emission in the Perseus Molecular Cloud with the COSMOSOMAS Experiment

    Microsoft Academic Search

    R. A. Watson; R. Rebolo; J. A. Rubiño-Martín; S. Hildebrandt; C. M. Gutiérrez; S. Fernández-Cerezo; R. J. Hoyland; E. S. Battistelli

    2005-01-01

    We present direct evidence for anomalous microwave emission in the Perseus molecular cloud, which shows a clear rising spectrum from 11 to 17 GHz in the data from the COSMOSOMAS experiment. By extending the frequency coverage using W ilkinson Microwave Anisotropy Probe maps convolved with the COSMOSOMAS scanning pattern, we reveal a peak flux density of 42+\\/-4 Jy at 22

  8. Electric Dipole Emission by Fulleranes and Galactic Anomalous Microwave Emission

    Microsoft Academic Search

    Susana Iglesias-Groth

    2005-01-01

    We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes (single and multishell) in various phases of the interstellar medium. Using the formalism of Draine & Lazarian for the rotational dynamics of these molecules in various astrophysical environments, we find effective rotation rates in the range 1-65 GHz with a trend toward lower rotational frequency as the

  9. Constraints on free-free emission from Anomalous Microwave Emission Sources in the Perseus Molecular Cloud

    E-print Network

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

    2013-01-01

    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\\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.

  10. 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

  11. Detection of Anomalous Microwave Emission in the Pleiades Reflection Nebula with Wilkinson Microwave Anisotropy Probe and the COSMOSOMAS Experiment

    Microsoft Academic Search

    R. Génova-Santos; R. Rebolo; J. A. Rubiño-Martín; C. H. López-Caraballo; S. R. Hildebrandt

    2011-01-01

    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° radius around R.A. = 56fdg24, decl. = 23fdg78 (J2000) is 2.15 ± 0.12 Jy at 22.8 GHz, where

  12. Polarization Observations of the Anomalous Microwave Emission in the Perseus Molecular Complex with the COSMOSOMAS Experiment

    Microsoft Academic Search

    E. S. Battistelli; R. Rebolo; J. A. Rubiño-Martín; S. R. Hildebrandt; R. A. Watson; C. Gutiérrez; R. J. Hoyland

    2006-01-01

    The anomalous microwave emission detected in the Perseus molecular complex by Watson et al. has been observed at 11 GHz through dual orthogonal polarizations with the COSMOSOMAS experiment. Stokes U and Q maps were obtained at a resolution of ~0.9d for a 30°×30° region including the Perseus molecular complex. Faint polarized emission has been measured; we find Q=-0.2%+\\/-1.0% and U=-3.4+1.8-1.4%,

  13. A Case Against Spinning PAHs as the Source of the Anomalous Microwave Emission

    E-print Network

    Hensley, Brandon S

    2015-01-01

    We employ the all-sky map of the anomalous microwave emission (AME) produced by component separation of the microwave sky to study correlations between the AME and Galactic dust properties. We find that while the AME is highly correlated with all tracers of dust emission, fluctuations in the AME intensity per dust optical depth are uncorrelated with fluctuations in the emission from polycyclic aromatic hydrocarbons (PAHs), casting doubt on the association between AME and PAHs. Further, we find that the best predictor of the AME strength is the dust radiance and that the AME intensity increases with increasing radiation field strength, at variance with predictions from the spinning dust hypothesis. A reconsideration of other emission mechanisms, such as magnetic dipole emission, is warranted.

  14. Very Small Array observations of the anomalous microwave emission in the Perseus region

    Microsoft Academic Search

    Christopher T. Tibbs; Robert A. Watson; Clive Dickinson; Rodney D. Davies; Richard J. Davis; Simon Buckmaster; Carlos Del Burgo; Thomas M. O. Franzen; Ricardo Génova-Santos; Keith Grainge; Michael P. Hobson; Carmen P. Padilla-Torres; Rafael Rebolo; José Alberto Rubiño-Martín; Richard D. E. Saunders; Anna M. M. Scaife; Paul F. Scott

    2010-01-01

    The dust complex G159.6-18.5 in the Perseus region has previously been observed with the COSMOSOMAS experiment on angular scales of ~1°, and was found to exhibit anomalous microwave emission. We present the first high angular resolution observations of this dust complex, performed with the Very Small Array (VSA) at 33GHz, to help increase the understanding of the nature of this

  15. Evidence for the naphthalene cation in a region of the interstellar medium with anomalous microwave emission

    Microsoft Academic Search

    S. Iglesias-Groth; A. Manchado; D. A. Garc ´ ia-Hernandez; J. I. González Hernández; D. L. Lambert

    2008-01-01

    We report high resolution spectroscopy of the moderately reddened (A$_V$=3)\\u000aearly type star Cernis 52 located in a region of the Perseus molecular cloud\\u000acomplex with anomalous microwave emission. In addition to the presence of the\\u000amost common diffuse interstellar bands (DIBs) we detect two new interstellar or\\u000acircumstellar bands coincident to within 0.01% in wavelength with the two\\u000astrongest

  16. Evidence for the Naphthalene Cation in a Region of the Interstellar Medium with Anomalous Microwave Emission

    Microsoft Academic Search

    S. Iglesias-Groth; A. Manchado; D. A. García-Hernández; J. I. González Hernández; D. L. Lambert

    2008-01-01

    We report high-resolution spectroscopy of the moderately reddened (AV=3) early-type star Cernis 52 located in a region of the Perseus molecular cloud complex with anomalous microwave emission. In addition to the presence of the most common diffuse interstellar bands (DIBs) we detect two new interstellar or circumstellar bands coincident to within 0.01% in wavelength with the two strongest bands of

  17. Evidence for the naphthalene cation in a region of the interstellar medium with anomalous microwave emission

    E-print Network

    S. Iglesias-Groth; A. Manchado; D. A. Garc\\'\\ia-Hernández; J. I. González Hernández; D. L. Lambert

    2008-09-04

    We report high resolution spectroscopy of the moderately reddened (A$_V$=3) early type star Cernis 52 located in a region of the Perseus molecular cloud complex with anomalous microwave emission. In addition to the presence of the most common diffuse interstellar bands (DIBs) we detect two new interstellar or circumstellar bands coincident to within 0.01% in wavelength with the two strongest bands of the naphthalene cation (C$_{10}$H$_{8}^+$) as measured in gas-phase laboratory spectroscopy at low temperatures and find marginal evidence for the third strongest band. Assuming these features are caused by the naphthalene cation, from the measured intensity and available oscillator strengths we find that 0.008 % of the carbon in the cloud could be in the form of this molecule. We expect hydrogen additions to cause hydronaphthalene cations to be abundant in the cloud and to contribute via electric dipole radiation to the anomalous microwave emission. The identification of new interstellar features consistent with transitions of the simplest polycyclic aromatic hydrocarbon adds support to the hypothesis that this type of molecules are the carriers of both diffuse interstellar bands and anomalous microwave emission.

  18. Polarization Observations of the Anomalous Microwave Emission in the Perseus Molecular Complex with the Cosmosomas Experiment

    E-print Network

    E. S. Battistelli; R. Rebolo; J. A. Rubiño-Martín; S. R. Hildebrandt; R. A. Watson; C. Gutiérrez; R. J. Hoyland

    2006-07-07

    The anomalous microwave emission detected in the Perseus molecular complex by Watson \\ea has been observed at 11 GHz through dual orthogonal polarizations with the COSMOSOMAS experiment. Stokes U and Q maps were obtained at a resolution of \\sim 0.9deg. for a 30deg. X 30deg. region including the Perseus molecular complex. A faint polarized emission has been measured; we find Q=-0.2 % \\pm1.0%, while U=-3.4^{+1.8}_{-1.4}% both at the 95% confidence level with a systematic uncertainty estimated to be lower than 1% determined from tests of the instrumental performance using unpolarized sources in our map as null hypothesis. The resulting total polarization level is \\Pi = 3.4^{+1.5}_{-1.9}%. These are the first constraints on the polarization properties of an anomalous microwave emission source. The low level of polarization seems to indicate that the particles responsible for this emission in the Perseus molecular complex are not significantly aligned in a common direction over the whole region, as a consequence of either a high structural symmetry in the emitting particle or a low-intensity magnetic field. Our weak detection is fully consistent with predictions from electric dipole emission and resonance relaxation at this frequency.

  19. VSA Observations of the Anomalous Microwave Emission in the Perseus Region

    Microsoft Academic Search

    Christopher T. Tibbs; Robert A. Watson; Clive Dickinson; Rodney D. Davies; Richard J. Davis; Carlos del Burgo; Thomas M. O. Franzen; Ricardo Génova-Santos; Keith Grainge; Michael P. Hobson; Carmen P. Padilla-Torres; Rafael Rebolo; Jóse Alberto Rubiño-Martín; Richard D. E. Saunders; Anna M. M. Scaife; Paul F. Scott

    2009-01-01

    The dust feature G159.6--18.5 in the Perseus region has previously been\\u000aobserved with the COSMOSOMAS experiment \\\\citep{Watson:05} on angular scales of\\u000a$\\\\approx$ 1$^{\\\\circ}$, and was found to exhibit anomalous microwave emission.\\u000aWe present new observations of this dust feature, performed with the Very Small\\u000aArray (VSA) at 33 GHz, to help increase the understanding of the nature of this\\u000aanomalous

  20. 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.

  1. A search for interstellar anthracene towards the Perseus anomalous microwave emission region

    NASA Astrophysics Data System (ADS)

    Iglesias-Groth, S.; Manchado, A.; Rebolo, R.; González Hernández, J. I.; García-Hernández, D. A.; Lambert, D. L.

    2010-10-01

    We report the discovery of a new broad interstellar (or circumstellar) band at 7088.8 +/- 2.0 Å coincident to within the measurement uncertainties with the strongest band of the anthracene cation (C14H10+) as measured in gas-phase laboratory spectroscopy at low temperatures. The band is detected in the line of sight of star Cernis 52, a likely member of the very young star cluster IC 348, and is probably associated with cold absorbing material in an intervening molecular cloud of the Perseus star-forming region where various experiments have recently detected anomalous microwave emission. From the measured intensity and available oscillator strength we find a column density of implying that ~0.008 per cent of the carbon in the cloud could be in the form of C14H10+. A similar abundance has been recently claimed for the naphthalene cation in this cloud. This is the first location outside the Solar system where specific polycyclic aromatic hydrocarbons (PAHs) are identified. We report observations of interstellar lines of CH and CH+ that support a rather high column density for these species and for molecular hydrogen. The strength ratio of the two prominent diffuse interstellar bands at 5780 and 5797 Å suggests the presence of a `zeta'-type cloud in the line of sight (consistent with steep far-ultraviolet extinction and high molecular content). The presence of PAH cations and other related hydrogenated carbon molecules which are likely to occur in this type of clouds reinforces the suggestion that electric dipole radiation from fast-spinning PAHs is responsible of the anomalous microwave emission detected towards Perseus.

  2. Detection of anomalous microwave emission in the Perseus molecular cloud with the COSMOSOMAS experiment

    E-print Network

    R. A. Watson; R. Rebolo; J. A. Rubino-Martin; S. Hildebrandt; C. M. Gutierrez; S. Fernandez-Cerezo; R. J. Hoyland; E. S. Battistelli

    2005-03-31

    We present direct evidence for anomalous microwave emission in the Perseus molecular cloud, which shows a clear rising spectrum from 11 to 17 GHz in the data of the COSMOSOMAS experiment. By extending the frequency coverage using WMAP maps convolved with the COSMOSOMAS scanning pattern we reveal a peak flux density of 42 (+/-) 4 Jy at 22 GHz integrated over an extended area of 1.65 x 1.0 deg centered on RA = 55.4 (+/-) 0.1 deg and Dec = 31.8 (+/-) 0.1 deg (J2000). The flux density that we measure at this frequency is nearly an order of magnitude higher than can be explained in terms of normal galactic emission processes (synchrotron, free-free and thermal dust). An extended IRAS dust feature G159.6-18.5 is found near this position and no bright unresolved source which could be an ultracompact HII region or gigahertz peaked source could be found. An adequate fit for the spectral density distribution can be achieved from 10 to 50 GHz by including a very significant contribution from electric dipole emission from small spinning dust grains.

  3. 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.

  4. VizieR Online Data Catalog: Anomalous microwave emission in Galactic clouds (Planck+, 2014)

    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-Levy, 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.; Desert, F.-X.; Dickinson, C.; Diego, J. M.; Donzelli, S.; Dore, O.; Dupac, X.; Ensslin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Franceschi, E.; Galeotta, S.; Ganga, K.; Genova-Santos, R. T.; Ghosh, T.; Giard, M.; Gonzalez-Nuevo, J.; Gorski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernandez-Monteagudo, C.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihaenen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Laehteenmaeki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liguori, M.; Lilje, P. B.; Linden-Vornle, M.; Lopez-Caniego, M.; Macias-Perez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Marshall, D. J.; Martin, P. G.; Martinez-Gonzalez, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Miville-Deschenes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Norgaard-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.; Rubino-Martin, 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.

    2014-07-01

    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 0.408GHz up to 3000GHz. 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 60GHz. An analysis of the potential contribution of optically thick free-free emission from ultra-compact HII 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 20-35GHz except for the California nebula (NGC1499), 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 14-20K and an average emissivity index, ?d, of +1.8, while the non-AME regions are typically warmer, at 20-27K. 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 HII 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. (1 data file).

  5. Suggested Mechanism for the Anomalous Excitation of OH Microwave Emissions from H-II Regions

    Microsoft Academic Search

    A. H. Cook

    1966-01-01

    STRONG microwave emission lines at 18 cm have recently been reported from a number of sources1-3, the frequencies being close to those of the hyperfine components of the Lambda-doublet of the ground state (X 2Pi3\\/2, J = 3\\/2) as measured in the laboratory4. Lambda-doubling is due to coupling between the rotation of the nuclei and the orbital rotation of the

  6. Measurements of the Intensity and Polarization of the Anomalous Microwave Emission in the Perseus molecular complex with QUIJOTE

    E-print Network

    Génova-Santos, R; Rebolo, R; Peláez-Santos, A; López-Caraballo, C H; Harper, S; Watson, R A; Ashdown, M; Barreiro, R B; Casaponsa, B; Dickinson, C; Diego, J M; Fernández-Cobos, R; Grainge, K J B; Herranz, D; Hoyland, R; Lasenby, A; López-Caniego, M; Martínez-González, E; McCulloch, M; Melhuish, S; Piccirillo, L; Perrott, Y C; Poidevin, F; Razavi-Ghods, N; Scott, P F; Titterington, D; Tramonte, D; Vielva, P; Vignaga, R

    2015-01-01

    Anomalous microwave emission (AME) has been observed in numerous sky regions, in the frequency range ~10-60 GHz. One of the most scrutinized regions is G159.6-18.5, located within the Perseus molecular complex. In this paper we present further observations of this region (194 hours in total over ~250 deg^2), both in intensity and in polarization. They span four frequency channels between 10 and 20 GHz, and were gathered with QUIJOTE, a new CMB experiment with the goal of measuring the polarization of the CMB and Galactic foregrounds. When combined with other publicly-available intensity data, we achieve the most precise spectrum of the AME measured to date, with 13 independent data points being dominated by this emission. The four QUIJOTE data points provide the first independent confirmation of the downturn of the AME spectrum at low frequencies, initially unveiled by the COSMOSOMAS experiment in this region. We accomplish an accurate fit of these data using models based on electric dipole emission from spin...

  7. Hydrogenated fulleranes and the anomalous microwave emission of the dark cloud LDN 1622

    Microsoft Academic Search

    Susana Iglesias-Groth

    2006-01-01

    We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes under the physical conditions of the dark cloud (DC) LDN 1622. The abundance of fullerenes is estimated by fitting theoretical photoabsorption spectra to the characteristics of the ultraviolet (UV) bump extinction in DCs. The UV bump appears to be well reproduced by a mixture of fullerenes following

  8. Diffuse Microwave Emission Survey

    Microsoft Academic Search

    R. A. Shafer; J. C. Mather; A. Kogut; D. J. Fixsen; M. Seiffert; P. M. Lubin; S. M. Levin

    1996-01-01

    The Diffuse Microwave Emission Survey (DIMES) has been selected for a mission concept study for NASA's New Mission Concepts for Astrophysics program. DIMES will measure the frequency spectrum of the cosmic microwave background and diffuse Galactic foregrounds at centimeter wavelengths to 0.1% precision (0.1 mK), and will map the angular distribution to 20 muK per 6 degree field of view.

  9. Microwave Emission from Galactic Dust Grains

    E-print Network

    Draine, B T

    1999-01-01

    Observations of the cosmic microwave background have revealed a component of 10-60 GHz emission from the Galaxy which correlates with 100-140um emission from interstellar dust but has an intensity much greater than expected for the low-frequency tail of the "electric dipole vibrational" emission peaking at dust-correlated free-free emission. The anomalous emission could be due in part to magnetic dipole emission from thermal fluctuations of the magnetization within interstellar dust grains, but only if a substantial fraction of the Fe in interstellar dust resides in magnetic materials such as metallic iron or magnetite. The observed anomalous emission is probably due primarily to electric dipole radiation from spinning ultrasmall interstellar dust grains. This rotational emission is expected to be partially polarized. From the standpoint of minimizing confusion with non-CBR foregrounds, 60-120 GHz appears to be the optimal frequency window.

  10. Microwave Emission from Galactic Dust Grains

    E-print Network

    B. T. Draine; A. Lazarian

    1999-02-25

    Observations of the cosmic microwave background have revealed a component of 10-60 GHz emission from the Galaxy which correlates with 100-140um emission from interstellar dust but has an intensity much greater than expected for the low-frequency tail of the "electric dipole vibrational" emission peaking at \\~130um. This "anomalous emission" is more than can be accounted for by dust-correlated free-free emission. The anomalous emission could be due in part to magnetic dipole emission from thermal fluctuations of the magnetization within interstellar dust grains, but only if a substantial fraction of the Fe in interstellar dust resides in magnetic materials such as metallic iron or magnetite. The observed anomalous emission is probably due primarily to electric dipole radiation from spinning ultrasmall interstellar dust grains. This rotational emission is expected to be partially polarized. From the standpoint of minimizing confusion with non-CBR foregrounds, 60-120 GHz appears to be the optimal frequency window.

  11. Diffuse Microwave Emission Survey

    E-print Network

    Al Kogut

    1996-07-19

    The Diffuse Microwave Emission Survey (DIMES) has been selected for a mission concept study for NASA's New Mission Concepts for Astrophysics program. DIMES will measure the frequency spectrum of the cosmic microwave background and diffuse Galactic foregrounds at centimeter wavelengths to 0.1% precision (0.1 mK), and will map the angular distribution to 20 muK per 6 degree field of view. It consists of a set of narrow-band cryogenic radiometers, each of which compares the signal from the sky to a full-aperture blackbody calibration target. All frequency channels compare the sky to the same blackbody target, with common offset and calibration, so that deviations from a blackbody spectral shape may be determined with maximum precision. Measurements of the CMB spectrum complement CMB anisotropy experiments and provide information on the early universe unobtainable in any other way; even a null detection will place important constraints on the matter content, structure, and evolution of the universe. Centimeter-wavelength measurements of the diffuse Galactic emission fill in a crucial wavelength range and test models of the heat sources, energy balance, and composition of the interstellar medium.

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

    E-print Network

    Lazarian, A

    1998-01-01

    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 (amagnetic, 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 ...

  13. Microwave emission and crop residues

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    A series of controlled experiments were conducted to determine the significance of crop residues or stubble in estimating the emission of the underlying soil. Observations using truck-mounted L and C band passive microwave radiometers showed that for dry wheat and soybeans the dry residue caused negligible attenuation of the background emission. Green residues, with water contents typical of standing crops, did have a significant effect on the background emission. Results for these green residues also indicated that extremes in plant structure, as created using parallel and perpendicular stalk orientations, can cause very large differences in the degree of attenuation.

  14. Detection of Microwave Emission Associated with Earthquakes

    Microsoft Academic Search

    T. Maeda; T. Takano

    2006-01-01

    It was experimentally shown that rock crash by static pressure caused radio wave emissions at 300MHz, 2GHz and 22GHz. This result suggests that this microwave is emitted in the result of earthquakes. Encouraged by this circumstance, we aim to establish the computer system to detect microwave emissions associated with crustal alterations, which trigger earthquakes, by a microwave radiometer loaded on

  15. An Anomalous Component of Galactic Emission

    E-print Network

    E. M. Leitch; A. C. S. Readhead; T. J. Pearson; S. T. Myers

    1997-05-30

    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 7'. After point source removal, we detect significant emission with temperature spectral index beta ~ -2 towards the North Celestial Pole (NCP). Comparison of our data with the IRAS 100 micron map of the same fields reveals a strong correlation between this emission and the infrared dust emission. From the lack of detectable H-alpha emission, we conclude that the signals are consistent either with flat-spectrum synchrotron radiation, or with free-free emission from T_e ~ 10^6 K gas, probably associated with a large HI feature known as the NCP Loop. Assuming beta = -2.2, our data indicate a conversion T_f/I_(100 micron) = 0.075*nu(GHz)^-2.2 K/(MJy/sr). The detection of such a component suggests that we should be cautious in any assumptions made regarding foregrounds when designing experiments to map the microwave background radiation.

  16. Study of microwave emissivity characteristics of city

    Microsoft Academic Search

    Tao Zhang; Lixin Zhang; Lingmei Jiang; Yunqing Li

    2011-01-01

    The spectrums of different land types are very important in the application of remote sensing, which can be used in surface classification, change detection, and so on. The microwave emissivity of these land types are the foundation of land parameters retrieval using passive microwave remote sensing. As one of the most important land types, city’s contribution in a passive microwave

  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. Surveys of Microwave Emission from Air Showers

    Microsoft Academic Search

    Kazuyuki Kuramoto; Shoichi Ogio; Takashi Iijima; Tokonatsu Yamamoto

    2011-01-01

    A possibility of detection of microwave molecular bremsstrahlung radiation from Extensive Air Showers was reported by AMBER group [1] [2]. This method has a potential to provide a high duty cycle and a new technique for measuring longitudinal profile of EAS. To survey this microwave emission from EAS, we built prototype detectors using parabolic antenna dishes for broadcasting satellites, and

  19. 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...

  20. Magnetic Dipole Microwave Emission from Dust Grains

    E-print Network

    Draine, B T

    1999-01-01

    Thermal fluctuations in the magnetization of interstellar grains will produce magnetic dipole emission at frequencies below ~100 GHz. We show how to calculate absorption and emission from small particles composed of magnetic materials. The Kramers-Kronig relations for a dusty medium are generalized to include the possibility of magnetic grains. The frequency-dependent magnetic permeability is discussed for candidate grain materials, including iron and magnetite. We calculate emission spectra for various interstellar grain candidates. While paramagnetic grains or magnetite grains cannot account for the observed "anomalous" emission from dust in the 14-90 GHz range, stronger magnetic dipole emission will result if a fraction of the grain material is ferromagnetic, as could be the case given the high Fe content of interstellar dust. The observed emission from dust near 90 GHz implies that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in "GEMS"). However, we show ...

  1. Magnetic Dipole Microwave Emission from Dust Grains

    E-print Network

    B. T. Draine; A. Lazarian

    1998-07-01

    Thermal fluctuations in the magnetization of interstellar grains will produce magnetic dipole emission at frequencies below ~100 GHz. We show how to calculate absorption and emission from small particles composed of magnetic materials. The Kramers-Kronig relations for a dusty medium are generalized to include the possibility of magnetic grains. The frequency-dependent magnetic permeability is discussed for candidate grain materials, including iron and magnetite. We calculate emission spectra for various interstellar grain candidates. While paramagnetic grains or magnetite grains cannot account for the observed "anomalous" emission from dust in the 14-90 GHz range, stronger magnetic dipole emission will result if a fraction of the grain material is ferromagnetic, as could be the case given the high Fe content of interstellar dust. The observed emission from dust near 90 GHz implies that not more than 5% of interstellar Fe is in the form of metallic iron grains or inclusions (e.g., in "GEMS"). However, we show that if most interstellar Fe is in a moderately ferromagnetic material, it could contribute a substantial fraction of the observed 14-90 GHz emission, perhaps comparable to the contribution from spinning ultrasmall dust grains. The two emission mechanisms can be distinguished by measuring the emission from dark clouds. The expected polarization of magnetic dipole emission is discussed

  2. Microwave emissions from police radar

    E-print Network

    Fink, John Michael

    1994-01-01

    . . . . . . . . 43 TABLE V - Maximum Power Density Results by Model. . 44 TABLE VI - Ambient Condition Power Density Summary. . . . . . . . . TABLE VII - Anthropometric Data of the Human Population. . . . . TABLE VIII - Power Density Emission Summary... chosen as the focus of this study. Models that would reasonably simulate ocular and testicular positions inside the police car were designed based on an all male population. Two anthropometric documents were used to compile data on ocular...

  3. Quiescent microwave emission from late-type stars

    Microsoft Academic Search

    Manuel Gudel

    1994-01-01

    A diversity of stellar classes has been detected to be prolific sources of low-level, 'quiescent' microwave radiation. This emission is, in most cases, attributed to the persistent presence of mildly relativistic electrons in the coronae. Frequent or continuous particle acceleration is required to maintain a high level of gyrosynchrotron emission. Observations relevant to our understanding of quiescent microwave emission from

  4. Diffuse microwave emission of the interstellar medium : intensity and polarization

    Microsoft Academic Search

    Marc-Antoine Miville-Deschenes

    2009-01-01

    With the increasing number of experiments dedicated to the observation of the Cosmic Microwave Background, interest on the detailed properties of the foreground Galactic emission has risen. In particular the focus is shifting towards polarized microwave emission with the goal of detecting signature from primordial gravitational waves and inflation. This review describes the Galactic polarized and unpolarized emissions in the

  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. 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.

  7. TEMPERATURE DEPENDENCE OF MICROWAVE EMISSION FROM INDIUM ANTIMONIDE

    Microsoft Academic Search

    T. O. Poehler

    1967-01-01

    The microwave emission characteristics of n-type indium antimonide have been studied as a function of temperature and magnetic field intensity. Microwave emission at 10 GHz has been detected at temperatures as high as 250°K in a magnetic field of 6.5 kOe.

  8. Observation of Polarised Microwave Emission from Cosmic Ray Air Showers

    E-print Network

    Smida, R; Engel, R; Arteaga-Velazquez, J C; Bekk, K; Bertaina, M; Bluemer, 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; Hoerandel, J R; Huber, D; Huege, T; Kampert, K -H; Kang, D; Klages, H; Kleifges, M; Kroemer, O; Link, K; Luczak, P; Ludwig, M; Mathes, H J; Mayer, H J; Mathys, S; Melissas, M; Morello, C; Neunteufel, P; Oehlschlaeger, J; Palmieri, N; Pekala, J; Pierog, T; Rautenberg, J; Rebel, H; Riegel, M; Roth, M; Salamida, F; Schieler, H; Schoo, S; Schroeder, F G; Sima, O; Stasielak, J; Toma, G; Trinchero, G C; Unger, M; Weber, M; Weindl, A; Wilczynski, H; Will, M; Wochele, J; Zabierowski, J

    2013-01-01

    We report on the first direct measurement of the basic features 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 CROME (Cosmic-Ray Observation via Microwave Emission) experiment have been read out and searched for signatures of radio emission by high-energy air showers. Microwave signals have been detected for more than 30 showers with energies above $3\\times10^{16}$\\,eV. The observations presented in this Letter are consistent with a mainly forward-beamed, coherent and polarised emission process in the GHz frequency range. An isotropic, unpolarised radiation is disfavoured as the dominant emission model. The measurements show that microwave radiation offers a new means of studying air showers at very high energy.

  9. Galactic microwave emission at degree angular scales

    E-print Network

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

    1997-07-25

    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 sigma) with the Diffuse Infrared Background Experiment (DIRBE) 240, 140 and 100 microm 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 Kogut et al. (1996a; 1996b) 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.

  10. Anomalously low PAH emission from low-luminosity galaxies

    E-print Network

    David W. Hogg; Christy A. Tremonti; Michael R. Blanton; Douglas P. Finkbeiner; Nikhil Padmanabhan; Alejandro D. Quintero; David J. Schlegel; Nicholas Wherry

    2004-08-23

    The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC) near and mid-infrared imaging data partially overlaps the Sloan Digital Sky Survey (SDSS), with 313 visually selected (rPAH emission from the interstellar medium. As expected, we find a strong inverse correlation between [3.5]-[7.8] and visual color; galaxies red in visual colors (`red galaxies') tend to show very little dust and molecular emission (low `PAH-to-star' ratios), and galaxies blue in visual colors (`blue galaxies,' ie, star-forming galaxies) tend to show large PAH-to-star ratios. Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by dust lanes. Simple, visually inferred attenuation corrections bring the visual colors of these galaxies in line with those of face-on disks; ie, PAH emission is closely related to attenuation-corrected, optically inferred star-formation rates. Blue galaxies with anomalously low PAH-to-star ratios are all low-luminosity star-forming galaxies. There is some weak evidence in this sample that the deficiency in PAH emission for these low-luminosity galaxies may be related to emission-line metallicity.

  11. Extracting Microwave Emissivity Characteristics over City using AMSR-E

    Microsoft Academic Search

    T. Zhang; L. Zhang; L. Jiang; Y. Li

    2010-01-01

    The spectrums of different land types are very important in the application of remote sensing. Different spectrums of different land types can be used in surface classification, change detection, and so on. The microwave emissivity over land is the foundation of land parameters retrieval using passive microwave remote sensing. It depends on land type due to different objects' structure, moisture

  12. Radiometric Measurements of the Microwave Emissivity of Reproducible Breaking Waves

    E-print Network

    Reising, Steven C.

    Radiometric Measurements of the Microwave Emissivity of Reproducible Breaking Waves Sharmila measurements of breaking waves on the open ocean showed that the emission due to wave breaking varies measurements on the open ocean. Therefore, the authors conducted a wave basin experiment in which reproducible

  13. Detection of Microwave Emission from Coronal X-Ray Jets

    Microsoft Academic Search

    M. R. Kundu; K. Shibasaki; N. Nitta

    1997-01-01

    We present evidence of the detection of microwave emission at 17 GHz in association with coronal X-ray jets. We present two typical cases--one on the disk (1995 March 31) and the other at the limb (1992 August 25). For the disk event we see 17 GHz emission from the upper part of the jet base (active region loop or loops),

  14. Enhancement of LIBS emission using antenna-coupled microwave.

    PubMed

    Khumaeni, Ali; Motonobu, Tampo; Katsuaki, Akaoka; Masabumi, Miyabe; Ikuo, Wakaida

    2013-12-01

    Intensified microwave coupled by a loop antenna (diameter of 3 mm) has been employed to enhance the laser-induced breakdown spectroscopy (LIBS) emission. In this method, a laser plasma was induced on Gd?O? sample at a reduced pressure by focusing a pulsed Nd:YAG laser (532 nm, 10 ns, 5 mJ) at a local point, at which electromagnetic field was produced by introducing microwave radiation using loop antenna. The plasma emission was significantly enhanced by absorbing the microwave radiation, resulting in high-temperature plasma and long-lifetime plasma emission. By using this method, the enhancement of Gd lines was up to 32 times, depending upon the emission lines observed. A linear calibration curve of Ca contained in the Gd?O? sample was made. The detection limit of Ca was approximately 2 mg/kg. This present method is very useful for identification of trace elements in nuclear fuel and radioactive materials. PMID:24514526

  15. Microwave emission from flare star AT MIC

    Microsoft Academic Search

    O. B. Slee; G. J. Nelson; I. R. Tuohy; C. J. Rennie

    1981-01-01

    It is pointed out that the most convincing detection of a microwave flare was made during simultaneous optical and 5-GHz observations of the dMe 4.5 flare star AT Mic on 25 October 1980. This event was notable for its long duration and the good temporal correlation between the optical and microwave intensities. Unless the dimensions of the source are very

  16. Microwave Emission from Acoustoelectrically Oscillating n-InSb

    Microsoft Academic Search

    Tetsuya Arizumi; Takeshi Aoki; Kiyonori Hayakawa

    1967-01-01

    The microwave radiation of 4 GHz was emitted at 77°K from a bar of n-InSb with axis parallel to [110] direction, when it was subjected to an electric field of about 30 V\\/cm, with or without the magnetic field. The detected microwave emission consisted of a number of spikes and amplitude-modulated with the acoustoelectric oscillation. The length of the sample

  17. Effects of anomalous permittivity on the microwave heating of zinc oxide

    SciTech Connect

    Martin, L.P.; Dadon, D.; Rosen, M. [Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland (United States)] [Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland (United States); Gershon, D.; Rybakov, K.I.; Birman, A.; Calame, J.P.; Levush, B.; Carmel, Y. [Institute for Plasma Research, University of Maryland, College Park, Maryland (United States)] [Institute for Plasma Research, University of Maryland, College Park, Maryland (United States); Hutcheon, R. [Chalk River Laboratories, Chalk River, Ontario K0J1J0 (Canada)] [Chalk River Laboratories, Chalk River, Ontario K0J1J0 (Canada)

    1998-01-01

    Highly nonuniform heating has been observed in zinc oxide (ZnO) powder compacts exposed to 2.45 GHz microwaves in oxygen deficient atmospheres such as pure nitrogen or argon. This phenomenon manifests as a localized zone of rapid heating which propagates outward from the sample core, and is documented by real-time surface and core temperature measurements performed during the microwave exposure. Measurements of the complex permittivity, {epsilon}{double_prime}, during heating of identical ZnO samples in a conventional furnace and in a nitrogen atmosphere, demonstrated that {epsilon}{double_prime} experiences at least one significant maximum between 200 and 500{degree}C. Mass spectrometry results indicate that the peaks in {epsilon}{double_prime} correlate well with the rate of desorption of chemisorbed water from the surface of the ZnO powder. It was also noted that the nonuniform heating does not manifest when the microwave exposure is performed in air. Similarly, the anomalous peaks in {epsilon}{double_prime} are almost completely suppressed during heating in air. It is well known that oxygen adsorbs strongly to the surface of ZnO in the temperature range from room temperature to 300{degree}C, and that this adsorption results in a drastic decrease in the electrical conductivity and, thus, in {epsilon}{double_prime}. It is proposed, therefore, that the effect of water desorption upon the complex permittivity may be, in effect, counterbalanced by the adsorption oxygen from the atmosphere. The effect of this behavior may be significant during microwave processing, where nonuniform power absorption can result in extremely localized heating. {copyright} {ital 1998 American Institute of Physics.}

  18. 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.

  19. Title of dissertation: MICROWAVE EMISSION AND ELECTRON TEMPERATURE IN THE MARYLAND

    E-print Network

    Anlage, Steven

    ABSTRACT Title of dissertation: MICROWAVE EMISSION AND ELECTRON TEMPERATURE IN THE MARYLAND Richard Ellis Department of Physics The use of two magnetised plasma waves as electron temperature diagnos- tics for the Maryland centrifugal ecperiment (MCX) are explored. First, microwave emission

  20. 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

  1. Microwave noise emission from indium antimonide

    Microsoft Academic Search

    J. E. King

    1969-01-01

    It is shown that shot noise is the source of p-InSb emission and high field n-InSb emission. Low field n-InSb emission is caused by shot noise arising from charge bursts in a high field region along the contact.

  2. Microwave anomalous propagation (AP) measurement over Akure South-Western Nigeria

    NASA Astrophysics Data System (ADS)

    Adediji, A. T.; Ajewole, M. O.

    2010-04-01

    Anomalous propagation (Anaprop) of microwave radiation is known to be caused by several meteorological conditions. In this study, radio refractive index and modified refractivity gradient were computed using the results of measurements of atmospheric pressure, temperature and relative humidity made in Akure (7.15°N, 5.12°E), South Western Nigeria using Davis 6162 Wireless Vantage Pro2 weather stations (Integrated Sensor Suite, ISS) positioned at five different height levels beginning from the ground surface and at intervals of 50 m from the ground to a height of 200 m on a tower/mast owned by the Nigeria Television Authority (NTA) located at Iju in Akure north local government area of Ondo state but which is no longer being used. The study utilized one year of data measured between January and December 2008. From the results, the modified refractivity was calculated and found to increase with increasing altitude. The values were observed to be generally high during the rainy periods and generally low during the dry periods. The study also revealed that for microwave propagation in this geographic zone, the propagation condition is mostly super-refractive.

  3. Microwave Emission and Electron Temperature in the Maryland Centrifugal Experiment

    NASA Astrophysics Data System (ADS)

    Reid, Remington R.

    The use of two magnetised plasma waves as electron temperature diagnostics for the Maryland centrifugal ecperiment (MCX) are explored. First, microwave emission in the whistler mode is examined and ultimately found to be a poor candidate for diagnostic purposes owing to reflections from elsewhere in the plasma confusing the signal. Second, the electron Bernstein wave is found to offer promise as means to measure the radial electron temperature profile. Several numeric codes are developed to analyze the observed microwave emission and calculate the electron temperature profile. Measurements of electron Bernstein wave emission indicate that the electrons in the plasma attain temperatures close to 100 eV. Clear evidence is shown that the measurements are not influenced by reflections or emission from hot (Te > 1keV) superthermal electrons. The measured electron temperature is shown to be in reasonable agreement with recent measurements of the plasma ion temperature.

  4. 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.

  5. 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.

  6. Long-period oscillations of the solar microwave emission

    Microsoft Academic Search

    K. G. Kislyakova; V. V. Zaitsev; S. Urpo; A. Riehokainen

    2011-01-01

    Modulations of the microwave emission of the Sun at 11.7 GHz have been studied using more than 40 events observed in 2001\\u000a at the Metsähovi Radio Observatory. In nearly all the observed events, low-frequency modulations with periods of 3–90 min\\u000a were detected. As a rule, simultaneous modulation of the emission at several frequencies was observed. One possible origin\\u000a of such

  7. Suprathermal microwave emission from the plasma focus

    Microsoft Academic Search

    G. Herziger; H. Krompholz; L. Michel; K. Schoenbach

    1977-01-01

    Time-resolved microwave measurements were performed at a 1 kG plasma focus. Radiation within the frequency ranges (0.26-1.8) times 10 to the 10th power Hz and (2.65-4.0) times 10 to the 10th power Hz was detected along with a two-peak soft X-ray pulse at pinch. The maximum output of the lower frequency radiation corresponded in time to the first peak in

  8. Microwave acoustic noise emission from InSb

    Microsoft Academic Search

    W. Duncan; J. Livingstone

    1970-01-01

    Microwave noise emission observed from InSb when used as an acousto-electric amplifier has been found to be both electromagnetic and acoustic in nature. An acoustic delay rod differentiated between these phenomena due to the great difference in propagation velocities.

  9. Comparing coherent microwave emission from LPM and BH showers

    Microsoft Academic Search

    John P. Ralston; Douglas W. McKay

    1991-01-01

    Coherent microwave emission offers a promising probe of cosmic ray events in the UHE region upwards of 10 exp 14 eV. It is possible that this means may allow detection of events which could not be detected in any other way, such as those initiated by UHE neutrinos from cosmic points sources. The method has the advantages that the target

  10. Comparing coherent microwave emission from LPM and BH showers

    Microsoft Academic Search

    John P. Ralston; Douglas W. McKay

    1991-01-01

    Coherent microwave emission offers a promising probe of cosmic ray events in the UHE region upwards of 1014 eV. It is possible that this means may allow detection of events which could not be detected in any other way, such as those initiated by UHE neutrinos from cosmic point sources. The method has the advantages that the target can be

  11. 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.

  12. Aircraft measurements of microwave emission from Arctic Sea ice

    USGS Publications Warehouse

    Wilheit, T.; Nordberg, W.; Blinn, J.; Campbell, W.; Edgerton, A.

    1971-01-01

    Measurements of the microwave emission from Arctic Sea ice were made with aircraft at 8 wavelengths ranging from 0.510 to 2.81 cm. The expected contrast in emissivities between ice and water was observed at all wavelengths. Distributions of sea ice and open water were mapped from altitudes up to 11 km in the presence of dense cloud cover. Different forms of ice also exhibited strong contrasts in emissivity. Emissivity differences of up to 0.2 were observed between two types of ice at the 0.811-cm wavelength. The higher emissivity ice type is tentatively identified as having been formed more recently than the lower emissivity ice. ?? 1971.

  13. Discovery of Microwave Emission from Four Nearby SolarType G Stars

    E-print Network

    Guedel, Manuel

    microwave radiation, and its free­free emission would be very difficult to detect even at the distanceDiscovery of Microwave Emission from Four Nearby Solar­Type G Stars Manuel G¨udel 1 , J¨urgen H. M years ago, but the microwave detection of other single solar­type stars has remained a challenge. Here

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

    E-print Network

    Conti, E; Sartori, G

    2014-01-01

    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.

  15. High frequency microwave emission from BSCCO intrinsic junctions

    Microsoft Academic Search

    Wan Wang; Kiejin Lee; Ienari Iguchi; Kazuto Hirata; Takashi Mochiku

    1999-01-01

    We studied the microwave emission properties of very thin mesa structures of high quality Bi2Sr2CaCu2O 8 (BSCCO) single crystals grown by the traveling solvent floating zone technique. To increase the anisotropy of crystal, the samples were annealed at 400-600°C for 1-20 hrs. The mesa height was 15-45 nm, for which 10-30 resistive hysteresis branches in the I-V characteristics might be

  16. Dispersionless atomic emission spectrometry with excitation in microwave plasma

    SciTech Connect

    Rigin, V.I.

    1987-09-01

    High-resolution spectrometers with inductively coupled plasma burners as a source of excitation have been widely recommended for use in multielement atomic emission spectroscopy. Using these spectrometers, up to 60 elements can be determined simultaneously at the lower limit of detectable contents. In this paper, a combination of sample preparation and gas-chromatographic separation of volatile compounds of the elements to be determined is used for a dispersionless atomic emission determination of microamounts of metals forming covalent volatile hydrides, with the excitation of the gaseous sample in the microwave plasma. Their analysis in coal and plant matter is given as an example.

  17. Anomalous Neutron Burst Emissions in Deuterium-Loaded Metals: Nuclear Reaction at Normal Temperature

    NASA Astrophysics Data System (ADS)

    Jiang, Song-Sheng; Xu, Xiao-Ming; Zhu, Li-Qun; Gu, Shao-Gang; Ruan, Xi-Chao; He, Ming; Qi, Bu-Jia

    2012-11-01

    Conventional nuclear fusion occurs in plasma at temperatures greater than 107°C or when energy higher than 10 keV is applied. We report a new result of anomalous neutron emission, also called cascade neutron burst emission, from deuterium-loaded titanium and uranium deuteride samples at room temperature. The number of neutrons in the large bursts is measured as up to 2800 in less than a 64-?s interval. We suggest that the anomalous cascade neutron bursts are correlated with deuterium-loaded metals and probably the result of nuclear reactions occurring in the samples.

  18. Microwave emission above steady and moving sunspots

    NASA Technical Reports Server (NTRS)

    Drago, F. Chiuderi; Alissandrakis, C.; Hagyard, M.

    1987-01-01

    Two-dimensional maps of radio brightness temperature and polarization, computed assuming thermal emission with free-free and gyroresonance absorption, are compared with observations of active region 2502, performed at Westerbork at lambda = 6.16 cm during a period of 3 days in June 1980. The computation is done assuming a homogeneous model in the whole field of view and a force-free extrapolation of the photospheric magnetic field observed at MSFC with a resolution of 2.34 arcsec. The mean results are the following: (1) a very good agreement is found above the large leading sunspot of the group, assuming a potential extrapolation of the magnetic field and a constant conductive flux in the transition region ranging from .2 x 10 to the 6th to 10 to the 7th erg/sq cm 5; (2) a strong radio source, associated with a new-born moving sunspot, cannot be ascribed to thermal emission. It is suggested that this source may be due to synchrotron radiation by mildly relativistic electrons accelerated by resistive instabilities occurring in the evolving magnetic configuration. An order-of-magnitude computation of the expected number of accelerated particles seems to confirm this hypothesis.

  19. Microwave emission and scattering from vegetated terrain

    NASA Technical Reports Server (NTRS)

    Sibley, T. G.

    1973-01-01

    Models are developed for the apparent temperature and backscattering coefficient of vegetated terrain to illustrate the effects of vegetation on the sensitivity of these parameters to variations of soil moisture. Three types of terrain are simulated for both the passive and the active case: a uniform canopy over a smooth surface, plant rows on a smooth surface, and plant rows on a rough surface. In each case the canopy is defined by its overall dimensions and by its electric permittivity, which is determined from Weiner model for dielectric mixture. Emission and scattering from both the soil and the canopy are considered, but atmospheric effects are neglected. Calculated data indicate that the sensitivity of the apparent temperature and backscattering coefficient to variations of soil moisture, decreases as the amount of vegetation increases. It is shown that the same effect results from increasing signal frequency or angle of incidence.

  20. 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.

  1. Determination of Silicon, Iron, and Vanadium in Petroleum Coke by Microwave Digestion-Microwave Plasma Torch Atomic Emission Spectrometry

    Microsoft Academic Search

    J. Zhang; L. Li; Q. Zhang; Y. Yang; Q. Jin

    2007-01-01

    Using microwave plasma torch (MPT) as an excitation light source, argon as support gas, the sample solution was introduced into plasma by pneumatic nebulization system. The determination of silicon, iron, and vanadium in petroleum coke by microwave plasma torch atomic emission spectrometry (MPT-AES) was studied. The experimental conditions were optimized and chosen. The effects of coexistent ions on silicon, iron,

  2. Multielement determination of major elements in polymer additives by microwave induced plasma atomic emission spectrometry after microwave digestion

    Microsoft Academic Search

    Krzysztof Jankowski; Anna Jerzak; Anna Sernicka-Poluchowicz; Ludwik Synoradzki

    2001-01-01

    A method for multielement determination of major elements in polymer additives by microwave induced plasma atomic emission spectrometry (MIP-AES) has been elaborated. Microwave digestion with nitric acid was selected for sample preparation because of its speed and versatility. Sodium nitrate was added to the digestion mixture in order to reduce phosphorus losses. The precision obtained varied between 2 and 4.5%

  3. Generation-recombination noise and the microwave emission from InSb

    Microsoft Academic Search

    R. G. van Welzenis; J. J. Lodder

    1973-01-01

    A classification of the microwave emission phenomena from InSb is given. An explanation for the high-field microwave emission is proposed. Experimental evidence supporting this theory is discussed. New experimental results obtained by using pulsed high electric fields in a constant-voltage configuration are presented. One result is the observation of microwave emission in the absence of magnetic field. Another result is

  4. Microwave Absorption, Emission and Scattering: Trace Gases and Meteorological Parameters

    NASA Astrophysics Data System (ADS)

    Kunzi, Klaus; Bauer, Peter; Eresmaa, Reima; Eriksson, Patrick; Healy, Sean B.; Mugnai, Alberto; Livesey, Nathaniel; Prigent, Catherine; Smith, Eric A.; Stephens, Graeme

    Space-borne remote sensing techniques are widely used today to investigate the atmosphere, both by operational and experimental instruments on a large number of satellites. Sensors operating in the microwave range, defined as being wavelengths from 10 to 0.1 cm, frequency 3-300 GHz (microwaves also comprise sub-millimetre waves or frequencies up to 3,000 GHz) of the electromagnetic spectrum were among the first instruments used for this purpose from the ground and on board air- and space-borne platforms. Those instruments measured the thermal emission from a molecular resonance or used the absorption and scattering properties of water droplets or ice crystals to obtain information on atmospheric parameters and composition.

  5. Microwave emission from spinning dust in circumstellar disks

    E-print Network

    Roman R. Rafikov

    2006-02-01

    In the high density environments of circumstellar disks dust grains are expected to grow to large sizes by coagulation. Somewhat unexpectedly, recent near-IR observations of PAH features from disks around Herbig Ae/Be stars demonstrate that substantial amount of dust mass in these disks (up to several tens of per cent of the total carbon content) can be locked up in particles with sizes ranging from several to tens of nanometers. We investigate the possibility of detecting the electric dipole emission produced by these nanoparticles as they spin at thermal rates (tens of GHz) in cold gas. We show that such emission peaks in the microwave range and dominates over the thermal disk emission at \

  6. Microdetermination of phosphorus in organic materials from polymer industry by microwave-induced plasma atomic emission spectrometry after microwave digestion

    Microsoft Academic Search

    Krzysztof Jankowski

    2001-01-01

    Microwave digestion with nitric acid precedes the determination of phosphorus in different materials from the polymer industry by microwave-induced plasma atomic emission spectrometry (MIP-AES). Atomic emission is measured at the P I 213.618-nm line. The experimental detection limit (DL) is 150 ng ml?1. The accuracy of the method was evaluated with the analysis of certified reference material NIST SRM 1568A

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Galactic Microwave Emission from Spinning Dust: The Green Bank Galactic Plane Survey

    Microsoft Academic Search

    D. P. Finkbeiner; G. Langston; T. Minter

    2002-01-01

    Cosmic Microwave Background (CMB) experiments in recent years have attained a sufficient sensitivity to detect dust-correlated microwave emission at 15-30 GHz from dust in the Milky Way. At such frequencies, this dust-correlated emission dominates free-free, synchrotron, and other foregrounds. Draine & Lazarian (1998) proposed that this emission might be electric dipole emission from rapidly spinning dust grains. We have recently

  12. A Search for Microwave Emission From Ultra-High Energy Cosmic Rays

    E-print Network

    Alvarez-Muñiz, J; Bogdan, M; Bohá?ová, M; Bonifazi, C; Carvalho, W R; Neto, J R T de Mello; Luis, P Facal San; Genat, J F; Hollon, N; Mills, E; Monasor, M; Privitera, P; Reyes, L C; d'Orfeuil, B Rouille; Santos, E M; Wayne, S; Williams, C; Zas, E; Zhou, J

    2012-01-01

    We present a search for microwave emission from air showers induced by ultra-high energy cosmic rays with the MIcrowave Detection of Air Showers (MIDAS) experiment. No events were found, ruling out a wide range of power flux and coherence of the putative emission, including those suggested by recent laboratory measurements.

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

    Microsoft Academic Search

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

    2007-01-01

    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

  14. Impact of ice temperature on microwave emissivity of thin newly formed sea ice

    Microsoft Academic Search

    Byong Jun Hwang; Jens K. Ehn; David G. Barber

    2008-01-01

    This study examines the impact of ice temperature on microwave emissivity over thin, newly formed sea ice at 6, 19, and 37 GHz during October 2003 in the southern Beaufort Sea, where the physical properties of newly formed sea ice were coincidently measured with microwave emissions. Six ice stations with distinct properties were selected and divided according to ice surface

  15. Microwave emission due to hypervelocity impacts and its correlation with mechanical destruction

    Microsoft Academic Search

    T. Takano; Y. Murotani; K. Maki; T. Toda; A. Fujiwara; S. Hasegawa; A. Yamori; H. Yano

    2002-01-01

    Microwave emission due to hypervelocity impacts on metallic plates has been found. The targets used in the experiment are aluminum plates with various thicknesses. The projectile, a nylon cylinder with metal screw of 0.21 gm, was accelerated up to the velocity of 4 km\\/s; a heterodyne receiver detected the microwave at 22 GHz. The emission is a random sequence of

  16. Microwave emission experiment with hypervelocity impacts and applications of its results

    Microsoft Academic Search

    T. Takano; Y. Murotani; T. Toda; A. Fujiwara; S. Hasegawa; S. Yamori

    2001-01-01

    The experiments to detect microwave emission due to hypervelocity impacts have been carried out with significant improvements of time resolution. We can investigate waveforms up to 1 n sec so that the energy of the emitted microwave can be estimated. The emission is a random sequence of pulses which lasts more than 10 mu sec depending on the target destruction.

  17. High-pressure microwave dissolution of ceramics prior to trace metal determinations by microwave induced plasma atomic emission spectrometry

    Microsoft Academic Search

    Henryk Matusiewicz

    1993-01-01

    A commercial laboratory microwave acid digestion system was evaluated for the acid dissolution of ceramic powders (Al2O3, AlN, BN and Si3N4) prior to the determination of their trace element content by microwave induced plasma atomic emission spectrometry. Newly designed vessels, capable of withstanding internal pressures of over 110 bar, provide rapid and satisfactory results for sample dissolution. Sample preparation time

  18. Experimental study on the emission spectra of microwave plasma at atmospheric pressure

    SciTech Connect

    Zhang, Boya; Wang, Qiang; Zhang, Guixin, E-mail: guixin@mail.tsinghua.edu.cn [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Shanshan [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Shenzhen Power Supply Co. Ltd., Shenzhen 518000, Guangdong (China)

    2014-01-28

    An experimental study on microwave plasma at atmospheric pressure was conducted by employing optical emission spectroscopy. Based on a microwave plasma generation device developed for nanoparticle synthesis, we studied the influence of input microwave power and gas flow rate on the optical emission behaviors and electron temperature of plasma using Ar, He, and N{sub 2} as working gas, respectively. The physics behind these behaviors was discussed. The results are useful in characterizing microwave plasma at atmospheric pressure and can be used for improving nanoparticle synthesis system for commercial use in the future.

  19. Microwave Emission at High Galactic Latitudes in the Four-Year DMR Sky Maps

    Microsoft Academic Search

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

    1996-01-01

    We use the COBE 8 Differential Microwave Radiometers (DMR) 4 yr 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

  20. MICROWAVE POPCORN EMISSIONS RELEASED DURING COOKING AND BAG OPENING

    EPA Science Inventory

    Data are not currently available on the contaminants released when microwave popcorn, flavorings and bags are heated to microwave temperatures. Thus, the primary goal of this work is to identify and quantify contaminants emitted while popping and opening a bag of microwave popcor...

  1. A capacitively coupled microwave plasma atomic emission spectrometer for the determination of trace metals in microsamples

    Microsoft Academic Search

    Andrea M. Pless; Benjamin W. Smith; Mikhail A. Bolshov; James D. Winefordner

    1996-01-01

    A capacitively coupled microwave plasma operating at 450 to 850 W is used for atomic emission spectroscopy. The laboratory-constructed system contains a tungsten cup electrode capable of holding a volume of up to 30 ?l. Microwaves are used to dry the sample, while at higher powers the plasma is ignited for sample vaporization and excitation. The entire analysis can be

  2. Dependence of microwave emissions from hypervelocity impacts on the target material

    Microsoft Academic Search

    K. Maki; E. Soma; T. Takano; A. Fujiwara; A. Yamori

    2005-01-01

    Microwave emissions due to hypervelocity impacts and their dependence on the target material are described. Microwave signals were measured for four kinds of target materials: aluminum, alumina ceramic, red brick, and polyurethane rubber. The signals were composed of two kinds of wave form: intermittent sharp pulses and white noise. The pulse signals were emitted strongly, especially with the aluminum target.

  3. Observed effects of soil organic matter content on the microwave emissivity of soils

    NASA Technical Reports Server (NTRS)

    O'Neill, P. E.; Jackson, T. J.

    1990-01-01

    In order to determine the significance of organic matter content on the microwave emissivity of soils when estimating soil moisture, field experiments were conducted in which 1.4 GHz microwave emissivity data were collected over test plots of sandy loam soil with different organic matter levels (1.8, 4.0, and 6.1 percent) for a range of soil moisture values. Analyses of the observed data show only minor variation in microwave emissivity due to a change in organic matter content at a given moisture level for soils with similar texture and structure. Predictions of microwave emissivity made using a dielectric model for aggregated soils exhibit the same trends and type of response as the measured data when appropriate values for the input parameters were utilized.

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

    E-print Network

    Smith, Michael Robert

    1983-01-01

    THE PREDICTION OF ROOT ZONE SOIL MOISTURE WITH A WATER BALANCE - MICROWAVE EMISSION MODEL A Thesis by MICHAEL ROBERT SMITH Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirements for the degree... of Committee) A. J. Blanchard (Member) D. R. Smith (Member) H i man (Member) . Jones r. ead of Department) May 1983 ABSTRACT The Prediction of Root lone Soil Moisture with a Water Balance-Microwave Emission Model. (May 1983) Michael Robert Smith, B...

  5. Microwave emission from Xray bright solarlike stars: The FG main sequence and beyond

    E-print Network

    Guedel, Manuel

    Microwave emission from X­ray bright solar­like stars: The F­G main sequence and beyond M. G¨udel 1 of nonthermal particles. The microwave flux densities were observed with the VLA at 8.4 GHz. Radio emission has, selected as the apparently strongest X­ray sources in their class as detected in the ROSAT All­Sky Survey

  6. On the Possible Connection between Photospheric 5Min Oscillation and Solar Flare Microwave Emission

    Microsoft Academic Search

    A. G. Kislyakov; V. V. Zaitsev; A. V. Stepanov; S. Urpo

    2006-01-01

    Dynamic spectra of low-frequency modulation of microwave emission from solar flares are obtained. Data of 15 bursts observed\\u000a in 1989–2000 with Metshovi radio telescope at 37 GHz have been used. During 13 bursts a 5-min modulation of the microwave\\u000a emission intensity was detected with the frequency of ?I = 3.2 0.24 (1?) mHz. Five bursts revealed a 5-min wave superimposed

  7. 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

  8. Microwave backscattering and emission model for grass canopies

    SciTech Connect

    Saatchi, S.S. (Jet Propulsion Lab., Pasadena, CA (United States)); Le Vine, D.M. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center); Lang, R.H. (George Washington Univ., Washington, DC (United States). Dept. of Electrical and Computer Engineering)

    1994-01-01

    Microwave radar and radiometer measurements of grasslands indicate a substantial reduction in sensor sensitivity to soil moisture in the presence of a thatch layer. When this layer is wet it masks changes in the underlying soil, making the canopy appear warm in the case of passive sensors (radiometer) and decreasing backscatter in the active case (scatterometer). A model for a grass canopy with thatch will be presented in this paper to explain this behavior and to compare with observations. The canopy model consists of three layers: grass, thatch, and the underlying soil. The grass blades are modeled by elongated elliptical discs and the thatch is modeled as a collection of disk shaped water droplets (i.e., the dry matter is neglected). The ground is homogeneous and flat. The distorted Born approximation is used to compute the radar cross section of this three layer canopy and the emissivity is computed from the radar cross section using the Peake formulation for the passive problem. Results are computed at L-band (1.4 GHz) and C-band (4.75 GHz) using canopy parameters (i.e., plant geometry, soil moisture, plant moisture, etc.) representative of Konza Prairie grasslands. The results are compared to C-band scatterometer measurements and L-band radiometer measurements at these grasslands.

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

    Microsoft Academic Search

    Dan Hooper; Douglas P. Finkbeiner; Gregory Dobler

    2007-01-01

    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

  10. 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

  11. Can Charge Exchange Explain Anomalous Soft X-Ray Emission in the Cygnus Loop?

    NASA Astrophysics Data System (ADS)

    Cumbee, R. S.; Henley, D. B.; Stancil, P. C.; Shelton, R. L.; Nolte, J. L.; Wu, Y.; Schultz, D. R.

    2014-06-01

    Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this "anomalously" enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O8 +, O7 +, N7 +, N6 +, C6 +, and C5 + with H with an energy of 1 keV u-1 (438 km s-1). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O7 + + H, does provide for a statistically significant improvement over a pure shock model.

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

    PubMed

    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 performance is enabled by a new concept of sideband amplitude and phase controls using an electro-optic modulator and an optical filter. This concept enables energy efficient operation in active MWP notch filters, and opens up a pathway toward enabling low-power nanophotonic devices as high-performance RF filters. PMID:24177078

  13. A noncontact method for detecting acoustic emission using a microwave Doppler radar motion detector.

    PubMed

    Smith, Gregory C

    2005-09-01

    A noncontact method for detecting acoustic emission was developed, using a microwave Doppler radar detector and an active band-pass filter. A theoretical model was developed and a prototype sensor was built and tested. The prototype responds to acoustic emissions (AE), from pencil lead break tests, at ranges up to 1.5 feet. PMID:16285461

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

    Microsoft Academic Search

    Luis Gras; Juan Mora; José L Todol??; Antonio Canals; Vicente Hernandis

    1999-01-01

    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

  15. Model-estimated microwave emissions from rain systems for remote sensing applications

    Microsoft Academic Search

    Mikhail T. Smirnov; Peter F. Meischner

    1996-01-01

    A simple model for estimating the upward and downward microwave emission from rain layer types above ground is presented. The emission properties of the rain layers are estimated from physical quantities such as the optical depth, the single- scattering albedo, the physical temperature, and a given drop size distribution for Mie scattering calculations. The underlying surface is characterized by the

  16. Detection of microwave emission by means of SN point contacts

    Microsoft Academic Search

    Iu. G. Bevza; V. I. Karamushko; I. M. Dmitrenko

    1977-01-01

    The characteristics of microwave detection were studied for superconductor\\/normal metal (S-N) point contacts in the absence of a dc transport current. Nb-Sn, Nb-Cu, Cu-Nb, and Cu-Sn clamped contacts (the first element forming the point) were prepared in liquid helium and were tested in a rectangular microwave waveguide. The resistance of the contacts ranged from 1 to 100 ohms. The frequency

  17. A magnetically excited microwave plasma source for atomic emission spectroscopy with performance approaching that of the inductively coupled plasma

    Microsoft Academic Search

    Michael R. Hammer

    2008-01-01

    A novel magnetically excited microwave plasma emission source was developed and tested. Unlike previous microwave plasma sources which couple energy from the microwave electric field, this source couples energy from the magnetic field. The resultant plasma shape allows easy entrainment of wet sample aerosol, such as is produced by a conventional inductively coupled plasma (ICP) nebulizer and spray chamber, into

  18. Investigations on laser ablation–microwave induced plasma–atomic emission spectrometry using polymer samples

    Microsoft Academic Search

    F. Leis; H. E. Bauer; L. Prodan; K. Niemax

    2001-01-01

    The potential of laser ablation–microwave induced plasma–atomic emission spectrometry (LA–MIP–AES) for the analysis of plastic materials has been investigated. A Nd\\/YAG laser, operated in its fundamental mode at 1064 nm, was used to ablate small amounts of various plastics. The sample atoms were transported and excited in a closely neighbored continuously running microwave induced plasma (MIP) operated in argon or

  19. On-line preconcentration with activated carbon for microwave plasma torch atomic emission spectrometry

    Microsoft Academic Search

    Hanqi Zhang; Xianglin Yuan; Xiaojun Zhao; Qinhan Jin

    1997-01-01

    This paper presents a method whereby trace elements are adsorbed in NH4Cl?NH3 medium on activated carbon and then determined by microwave plasma torch atomic emission spectrometry (MPT-AES). The working conditions (including microwave forward power, gas flow rate, NH3?NH4Cl concentration in the sample solution, HCl concentration in the eluant, sample introduction rate and preconcentration time) were investigated in detail. The effects

  20. Features of ocean microwave emission changed by wind at 6 GHz

    Microsoft Academic Search

    Akira Shibata

    2006-01-01

    Ocean microwave emissions changed by the ocean wind at 6 GHz were investigated by combining data of the Advanced Microwave\\u000a Scanning Radiometer (AMSR) and SeaWinds, both aboard the Advanced Earth Observation Satellite-II (ADEOS-II). This study was\\u000a undertaken to improve the accuracy of the sea surface temperature (SST) retrieved from the AMSR 6 GHz data. Two quantities,\\u000a 6V*(H*), were defined by

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

    PubMed Central

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

    2015-01-01

    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. 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

  2. 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

  3. Sensitivities of an atmospheric profiling retrieval to the microwave land emissivity

    NASA Astrophysics Data System (ADS)

    Ruston, Benjamin; Baker, Nancy L.

    2004-12-01

    This study focuses on microwave land surface emissivity estimation over Northern Africa and the Middle East and the related impact on temperature and moisture retrievals. Land surface temperature retrievals are performed using a plane-parallel radiative transfer model, analyses from the Navy Operational Global Atmospheric Prediction System (NOGAPS) and data from the High Resolution Infrared Radiation Sounder Version 3 (HIRS/3). Infrared surface emissivity is indexed to each location using soil and vegetation databases provided by the Global Land Data Assimilation System (GLDAS), and spectral reflectance libraries of soil and vegetation. Initial microwave land emissivity estimates are made using a plane-parallel radiative transfer model, the infrared retrieved land surface temperatures, analyses from NOGAPS, and data from the Advanced Microwave Sounding Unit (AMSU). Perturbations of the atmospheric profiles and land surface temperatures provide estimates of the microwave emissivity error covariances necessary for retrievals and radiance assimilation. The error estimation is used in both the Naval Research Laboratory (NRL) 1DVAR retrieval, and for future use in 3DVAR radiance assimilation with the NRL Atmospheric Variational Data Assimilation System (NAVDAS). The window channels on AMSU/A have shown sensitivity to both temperature and moisture in the lowest five kilometers of the atmospheric profile, with these sensitivities strongly correlated to the estimate of the microwave land emissivity. Though the sensitivities are strongly correlated in the vertical dimension, an ability to extract meaningful profiling information from the microwave data is displayed. Further, the atmospheric sensitivity is linked to the precision to which the microwave radiances are estimated.

  4. Anomalous Dielectric Loss at Ferroelectric Domain Walls Revealed by Microwave Impedance Microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoyu; Ren, Yuan; Hu, Rongwei; Cheong, Sang-Wook; Lai, Keji

    2015-03-01

    Domain walls (DWs) in multiferroic materials, within which the ferroic order parameter changes its orientation, may possess emergent properties that are absent in the bulk domains. Combining the standard piezo-force microscopy (PFM), conductive atomic-force microscopy (C-AFM), and a novel microwave impedance microscopy (MIM) technique, we observed strong dielectric loss at the domain walls and vortex cores on the (001) charge neutral surface of hexagonal manganite YMnO3. The DW contrast was detected for a broad frequency range between 100MHz and 3GHz. The equivalent DW conductivity inferred from the MIM signals is estimated to be five orders of magnitude higher than that of the bulk YMnO3, which cannot be explained within the existing theoretical framework. By applying a DC bias on the MIM probe, we have also observed the transition from DW contrast to domain contrast in the impedance images. The MIM technique provides a unique opportunity to probe the nanoscale electronic anomalies in various topological defects, which will be crucial for future device applications of multiferroics.

  5. The Electron Injection Spectrum Determined by Anomalous Excesses in Cosmic Ray, Gamma Ray, and Microwave Signals

    E-print Network

    Tongyan Lin; Douglas P. Finkbeiner; Gregory Dobler

    2010-09-13

    Recent cosmic ray, gamma ray, and microwave signals observed by Fermi, PAMELA, and WMAP indicate an unexpected primary source of e+e- at 10-1000 GeV. We fit these data to "standard backgrounds" plus a new source, assumed to be a separable function of position and energy. For the spatial part, we consider three cases: annihilating dark matter, decaying dark matter, and pulsars. In each case, we use GALPROP to inject energy in log-spaced energy bins and compute the expected cosmic-ray and photon signals for each bin. We then fit a linear combination of energy bins, plus backgrounds, to the data. We use a non-parametric fit, with no prior constraints on the spectrum except smoothness and non-negativity. In addition, we consider arbitrary modifications to the energy spectrum of the "ordinary" primary source function, fixing its spatial part, finding this alone to be inadequate to explain the PAMELA or WMAP signals. We explore variations in the fits due to choice of magnetic field, primary electron injection index, spatial profiles, propagation parameters, and fit regularization method. Dark matter annihilation fits well, where our fit finds a mass of ~1 TeV and a boost factor times energy fraction of ~70. While it is possible for dark matter decay and pulsars to fit the data, unconventionally high magnetic fields and radiation densities are required near the Galactic Center to counter the relative shallowness of the assumed spatial profiles. We also fit to linear combinations of these three scenarios, though the fit is much less constrained.

  6. Microwave plasma continuous emissions monitor for trace-metals in furnace exhaust

    NASA Astrophysics Data System (ADS)

    Woskov, P. P.; Rhee, D. Y.; Thomas, P.; Cohn, D. R.; Surma, J. E.; Titus, C. H.

    1996-10-01

    A microwave plasma continuous emissions monitor has been successfully demonstrated for sensitive (<1 ppb), real time measurements of trace metals in furnace exhaust. The instrument uses a robust, up to 1.5 kW, 2.45 GHz microwave plasma sustained in a portion of the undiluted furnace exhaust flow for atomic emission spectroscopy. The waveguide device is constructed of refractory materials compatible with high-temperature environments (?500 °C) and is flange mountable into the inside of the furnace exhaust duct. Fused quartz fiber optics in close proximity to the plasma flame transmit the UV through visible emission (190-690 nm) to three spectrometers for simultaneous monitoring of several metals. This instrument has been used for continuous monitoring for a 49 h period with 0.5 s time resolution on a dc graphite electrode arc furnace during a soil vitrification test. Results are presented for chromium, manganese, and iron emissions during soil loading operations.

  7. Slurry sample introduction with microwave induced plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Matusiewicz, Henryk; Sturgeon, Ralph E.

    1993-04-01

    The successful direct introduction of aqueous slurry samples into a highly efficient TE 101 microwave plasma has been demonstrated. Slurry samples from a spray chamber are fed directly into the cavity with no desolvation apparatus. A V-groove, clog-free Babington-type nebulizer was evaluated for use with high solids content solutions. Slurry concentrations up to 10% m/v were used for the microwave induced plasma work with calibration by the standard additions method. Results are presented for the analysis of two NRCC Standard Reference Materials, i.e. TORT-1 (Lobster Hepatopancreas) and PACS-21 (Marine Sediment). Agreement between analytical results and certified values for the test elements Cd, Cu, Fe and Zn (in the range of 28-850 ?g/g) was good. No memory effects were evident and the nebulizer system had a rapid clean-out time.

  8. Establishing a Calibration for a Microwave Plasma Continuous Emissions Monitor For Stack Exhaust Metals

    Microsoft Academic Search

    G. J. Flores III; K. M. Green; P. P. Woskov; K. Hadidi; P. Thomas

    1998-01-01

    A real-time continuous emissions monitor for hazardous metals in stack exhaust is in development to replace the regulatory standard, EPA Method 29. A microwave plasma is sustained in ambient stack exhaust flow for real-time atomic emission spectroscopy. A metals injection calibration subsystem using a pneumatic nebulizer and standard metals solution is attached to the exhaust flow for real-time span calibration

  9. Observing System Simulation of Snow Microwave Emissions Over Data Sparse Regions— Part I: Single Layer Physics

    Microsoft Academic Search

    Do Hyuk Kang; Ana P. Barros

    2012-01-01

    The objective of this work is to develop a framework for monitoring snow water equivalent (SWE) and snowpack radiometric properties (e.g., surface emissivity and reflectivity) and microwave emissions in remote regions where ancillary data and ground-based observations for model calibration and\\/or data assimilation are lacking. For this purpose, an existing land surface hydrology model (LSHM) with single-layer (SL) snow physics

  10. Spectral Investigation of Acoustoelectric Domains in n-GaAs by Microwave Emission Studies

    Microsoft Academic Search

    Demir S. Zoroglu; I. C. Chang

    1970-01-01

    Microwave emission from n-GaAs crystals, under conditions of current instability with propagating acoustoelectric domains, was detected and analyzed for various stages of the total acoustic flux level in such domains. Frequency range covered extended from 0.2 to 4.5 GHz. Diagnostic experiments indicate that the emission is due to the electromechanical conversion of the acoustic flux as the propagating domain hits

  11. 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.

  12. 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.

  13. A simple parameterization of the L-band microwave emission from rough agricultural soils

    Microsoft Academic Search

    Jean-Pierre Wigneron; Laurent Laguerre; Yann H. Kerr

    2001-01-01

    A simple model for simulating the L-band microwave emission from bare soils is developed. The model is calibrated on a large set of measurements obtained during a three-month period over seven plots covering a wide range of surface roughness (representing the total range which can be expected on agricultural fields), soil moisture, and temperature conditions. The approach is based on

  14. Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing

    Microsoft Academic Search

    J. M. Melack; L. L. Hess; B. R. Forsberg; S. K. Hamilton; E. M. Novo

    2002-01-01

    Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning

  15. 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

  16. Field emission properties of phosphorus doped microwave plasma chemical vapor deposition diamond films by ion implantation

    E-print Network

    Lee, Jong Duk

    Field emission properties of phosphorus doped microwave plasma chemical vapor deposition diamond 2002; published 5 February 2003 Phosphorus doped polycrystalline diamond films were grown using ion to the conclusion that phosphorus ions and defects in the Si­diamond interface play an important role

  17. Diacetyl Emissions and Airborne Dust from Butter Flavorings Used in Microwave Popcorn Production

    Microsoft Academic Search

    Randy Boylstein; Chris Piacitelli; Ardith Grote; Richard Kanwal; Greg Kullman; Kathleen Kreiss

    2006-01-01

    In microwave popcorn workers, exposure to butter flavorings has been associated with fixed obstructive lung disease resembling bronchiolitis obliterans. Inhalation toxicology studies have shown severe respiratory effects in rats exposed to vapors from a paste butter flavoring, and to diacetyl, a diketone found in most butter flavorings. To gain a better understanding of worker exposures, we assessed diacetyl emissions and

  18. Effects of spatial inhomogeneities and microwave emission enhancement in random media: an experimental study

    Microsoft Academic Search

    Giovanni Macelloni; Paolo Pampaloni; Simonetta Paloscia; Roberto Ruisi

    1996-01-01

    The effects of spatial distribution of the scattering elements on microwave emission from random media have been investigated using an experimental model composed of long, thin vertical dielectric cylinders on a reflecting screen. The measurements have been carried out at 10 and 37 GHz, H, V polarizations and different nadir and azimuth angles. Random “uniform” and “cluster” distributions as well

  19. The MIDAS experiment: A prototype for the microwave emission of UltraHigh Energy Cosmic Rays

    Microsoft Academic Search

    M. Monasor; I. Alekotte; J. Alvarez-Muñiz; X. Bertou; M. Bodgan; M. Bohacova; C. Bonifazi; W. Carvalho; J. F. Genat; P. Facal San Luis; E. Mills; S. Wayne; L. C. Reyes; E. M. Santos; P. Privitera; C. Williams; E. Zas

    2011-01-01

    Recent measurements suggest that extensive air showers initiated by ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the electromagnetic spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100%

  20. Experimental study of the effects of spatial inhomogeneities on microwave emission from random media

    Microsoft Academic Search

    G. Macelloni; P. Pampaloni; S. Paloscia; R. Ruisi

    1995-01-01

    The effects of spatial distribution of the scattering elements on microwave emission from random media have been investigated using an experimental model composed of long, thin vertical dielectric cylinders on a reflecting screen. The measurements have been carried out at 10 GHz, H, V and 45° polarizations and different incidence angles between 10° and 50°. Uniform and cluster distributions with

  1. Detection of linear polarization in the microwave emission of Solar Active Regions

    Microsoft Academic Search

    C. E. Alissandrakis; F. Chiuderi-Drago

    1994-01-01

    We report the detection for the first time of linear polarization in the microwave emission above a Solar Active Region. The observations were made with the Westerbork Synthesis Radio Telescope, taking advantage of the very small bandwidth of a multichannel spectral line receiver. The intensity of the Stokes parameter U, measured at several points close to the line of zero

  2. Application of the microwave emission spectrometric system as a silicon-selective detector

    Microsoft Academic Search

    D. T. Bostick; Y. Talmi

    1977-01-01

    The microwave emission spectrometric (MES)-gas chromatographic (GC) detector has been applied to the quantitative determination of silicon-containing compounds. Three different types of discharges were tested: a helium or an argon discharge, both operated under reduced pressure, and an argon discharge operated at atmospheric pressure. The sensitivity and selectivity of the detector for silicon were determined for each discharge at eight

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

    Microsoft Academic Search

    Tadashi Takano; Seiji Sugita; Shingo Yoshida; Takashi Maeda

    2010-01-01

    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

  4. 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.

  5. 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.

  6. Direct solid atomic emission spectrometric analysis of metal samples by an argon microwave plasma torch coupled to spark ablation

    Microsoft Academic Search

    U. Engel; A. Kehden; E. Voges; J. A. C. Broekaert

    1999-01-01

    Spark ablation has been combined to microwave plasma torch atomic emission spectrometry for the direct analysis of compact metallic samples. The material is ablated by a medium voltage spark (450 V, 370 Hz) in a point-to-plane configuration and swept into a 100-W, 2.45-GHz argon microwave discharge. The microwave plasma is observed end-on and the radiation analysed with a polychromator. The

  7. A Program To Search For Transient Microwave Emission From GRBs And Other High-Energy Sources Using Archival WMAP Datasets

    Microsoft Academic Search

    J. Gregory Stacy; Gary L. Case; Daniel R. Hart; Peter D. Jackson; Christoph Winkler

    2007-01-01

    We report on a new program to search the public time-ordered datasets acquired with the Wilkinson Microwave Anisotropy Probe (WMAP) for transient signals associated with gamma-ray bursts (GRBs) and other high-energy sources. This program is an extension of earlier work in which we established the first limits on prompt microwave emission from GRBs using archival datasets from the Differential Microwave

  8. Emission of Microwave Photon Pairs by a Tunnel Junction

    NASA Astrophysics Data System (ADS)

    Forgues, Jean-Charles; Lupien, Christian; Reulet, Bertrand

    2014-07-01

    We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f1=4.4 and f2=7.2 GHz, while driving the junction with a microwave excitation of frequency f0=f1+f2. We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction.

  9. Emission of microwave photon pairs by a tunnel junction.

    PubMed

    Forgues, Jean-Charles; Lupien, Christian; Reulet, Bertrand

    2014-07-25

    We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f(1) = 4.4 and f(2) = 7.2 GHz, while driving the junction with a microwave excitation of frequency f(0) = f(1) + f(2). We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction. PMID:25105619

  10. Dependence of microwave emissions from hypervelocity impacts on the target material

    NASA Astrophysics Data System (ADS)

    Maki, K.; Soma, E.; Takano, T.; Fujiwara, A.; Yamori, A.

    2005-05-01

    Microwave emissions due to hypervelocity impacts and their dependence on the target material are described. Microwave signals were measured for four kinds of target materials: aluminum, alumina ceramic, red brick, and polyurethane rubber. The signals were composed of two kinds of wave form: intermittent sharp pulses and white noise. The pulse signals were emitted strongly, especially with the aluminum target. The energy emitted from each target was estimated from the signal detected after calibrating the measuring system. The energy of the pulses was greater for conductors than for insulators. We hypothesized that the microwaves were emitted from a discharge along a microcrack in the target. The signals detected in the experiment agreed well with theoretical results.

  11. A capacitively coupled microwave plasma atomic emission spectrometer for the determination of trace metals in microsamples

    NASA Astrophysics Data System (ADS)

    Pless, Andrea M.; Smith, Benjamin W.; Bolshov, Mikhail A.; Winefordner, James D.

    1996-01-01

    A capacitively coupled microwave plasma operating at 450 to 850 W is used for atomic emission spectroscopy. The laboratory-constructed system contains a tungsten cup electrode capable of holding a volume of up to 30 ?l. Microwaves are used to dry the sample, while at higher powers the plasma is ignited for sample vaporization and excitation. The entire analysis can be carried out in less than 5 min. A mixture of helium and hydrogen is used as the plasma gas. A spherical or cylindrical shaped plasma can be formed depending upon the gas flow rate and the microwave power selected. The effects of experimental parameters, such as gas flow rate, atomization power, electrode position and plasma shape are examined. Detection limits for Cd, Mg and Zn are in the low picogram range for a 10 ?l sample; the relative standard deviation is less than 10%.

  12. Behaviour of a desolvation system based on microwave radiation heating for use in inductively coupled plasma atomic emission spectrometry

    Microsoft Academic Search

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

    1997-01-01

    The present paper describes the preliminary results obtained with a desolvation system for inductively coupled plasma atomic emission spectrometry that incorporates a heating unit based on microwave (MW) radiation. This system has been called Microwave Desolvation System (MWDS). The results have proved that MW radiation can be considered as a good choice for aerosol heating in a sample introduction system.

  13. Microwave Emission Produced by the Interaction of an Intense Relativistic Electron Beam with a Spatially Modulated Magnetic Field

    Microsoft Academic Search

    M. Friedman; M. Herndon

    1972-01-01

    Intense microwave emission was detected when a pulsed relativistic electron beam traversed a spatially modulated magnetic field. The microwave intensity was >~70 dB above the noise level. The wavelength of the electromagnetic radiation was equal to the characteristic length of the rippled magnetic field. At a critical averaged magnetic field, the radiation appeared to be almost monochromatic (Deltalambdalambda~10%).

  14. Effects of different slow wave structures and finite magnetic field on microwave emission in a BWO

    SciTech Connect

    Young, D.; Ishihara, O. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Electrical Engineering; Grabowski, C.; Gahl, J.; Schamiloglu, E. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering

    1996-12-31

    In a Backward Wave Oscillator (BWO) an electron beam, guided by a strong applied magnetic field, flows into a waveguide with periodic ripple imposed on its wall. The periodic ripple in the waveguide causes oscillations in the electron beam to grow and allows high power microwave radiation to be extracted. Although a variety of slow wave structures have been used to produce high power microwaves in BWOs, no systematic study has been done to determine the effects of the shape of slow wave structure. The authors have carried out computer simulations, using the PIC mode MAGIC, to study these effects by using sinusoidal, square well, and saw tooth ripple structures along the waveguide. Electrons are emitted as a beam at the entrance of the waveguide at a fraction of the space charge limiting current with energy on the order of 1 MeV. Ripple amplitudes are set less than 5 mm with a period of between 5 mm to 15 mm. The waveguide has typical radius between 10 mm to 25 mm. Preliminary results suggest that in smoothly varying ripples, such as sinusoidal ripples, less output microwave power is produced than in angular structures, such as square well ripples. Since the UNM long-pulse BWO experiment has produced higher output microwave power by using nonuniform slow wave structures, particle simulations have also been carried out to examine effects of shape of nonuniform structures as well. Simulations are also in progress to study the effects of applied magnetic field strength on microwave emission in BWOs.

  15. Detecting microwave emissions from terrestrial sources: A feasibility study

    Microsoft Academic Search

    Thomas C. Ehlert; Thomas K. Ishii

    1992-01-01

    A Dicke receiver has been designed and constructed in our effort to detect the 22 GHz spontaneous emission from water vapor. The receiver compares the brightness temperatures of two waveguides, one containing gaseous H20 at low pressure, the other containing dry air. Each waveguide is terminated with polished brass, which provides a low background brightness temperature, at one end and

  16. Anomalous three-dimensional refraction in the microwave region by ultra-thin high efficiency metalens with phase discontinuities in orthogonal directions

    NASA Astrophysics Data System (ADS)

    Zhang, Kuang; Ding, Xumin; Zhang, Liang; Wu, Qun

    2014-10-01

    An ultrathin flat metalens that experimentally realizes three-dimensional microwave manipulation has been demonstrated as able to approach the theoretical limit of cross-polarization (cross-pol) conversion efficiency of the transmission, as predicted by Monticone et al (2013 Phys. Rev. Lett. 110 203903). The helicity-dependent phase change is introduced to the transmission and can be engineered by assembling the spatial orientation of each Pancharatnam–Berry phase element. By realizing the constant phase gradients in orthogonal directions, an anomalous non-coplanar refraction is unanimously demonstrated in the three-dimensional space under the circular-polarized incidence, and the refraction angle is well predicted with the generalized Snell’s law, derived with phase gradients in orthogonal directions. More importantly, the maximum conversion efficiency of the cross-pol transmission is as high as 24%, which approaches the upper-bound of the theoretical limit. The proposed metalens has only a single layer as thin as 0.001 ?, which massively reduces the thickness of the microwave lens along the wave propagation direction. With the great improvements in efficiency and the thickness reduction, as well as the excellent non-coplanar refraction, our design provides a promising approach to miniaturize, planarize and integrate multiple microwave components.

  17. Analysis of polarized microwave emission of Flare-Productive Active Region 9415

    E-print Network

    V. M. Bogod; G. B. Gelfreikh; F. Ch. Drago; V. P. Maximov; A. Nindos; T. I. Kaltman; B. I. Ryabov; S. Kh. Tokhchukova

    2003-09-16

    The results of the microwave observations of the Sun made with the RATAN-600 have shown the existence of many types of spectral peculiarities in polarized emission of active regions, which produce powerful flares. These phenomena happen at microwaves and reflect inhomogeneous structure of magnetic field in magnetospheres of flaring active regions in wide range of heights above the photosphere. In this presentation we demonstrate an analysis of the AR 9415 during all the period of its passage across the solar disk. Results of the study point out to existence of different scenarios of circular polarization variations in the radio wave band. Here, we separated the phenomenon of the cyclotron emission passage through the quasi-transverse magnetic field (QT-region) and several effects connected with flare activity of active region. New observational data are presented and compared with the data of several observatories: SSRT, NoRH, MDI SOHO, GOES and MEES. The preliminary interpretation of the phenomena are given.

  18. Reduction of Perfluorocompound Emissions by Microwave Plasma Torch

    NASA Astrophysics Data System (ADS)

    Hong, Yong C.; Kim, J. H.; Uhm, H. S.

    2002-11-01

    Surface cleanings are performed within a reduced pressure chamber by making use of perfluorocompounds (PFC) gases, which eventually contaminate the atmosphere. These contaminant gases are emitted with nitrogen gas, which is used for pump purges. In order to destruct all of the global warming gases including PFCs, we have developed a plasma abatement device, an electrodeless microwave plasma torch operated at the atmosphere pressure. The plasma abatement device is attached to the vacuum pump, which discharges the nitrogen gas with contaminants. The abatement was carried out using oxygen and air as an additive gases. The destruction and removal efficiency (DRE) of more than 98was achieved for tetrafluoromethane(CF4). The detailed characterization of CF4 abatement using Fourier Transform Infrared (FT-IR) and Quadrupole Mass Spectrometer (QMS) showed the major PFC by-products. Finally, experimental results indicate that the plasma abatement device for PFC destruction can be successfully used to abate all of the global warming gases in the semiconductor industry.

  19. A SSM\\/I Radiometer Simulator for Studies of Microwave Emission from Soil

    Microsoft Academic Search

    J. F. Galantowicz; A. W. England

    1992-01-01

    We describe a ground based simulator of the Defence Meteorological Satellite Program’s Special Sensor Microwaveflmager (DMSP SSW) and its integration with micrometeorological instrumentation for an investigation of microwave emission from moist and frozen soils. The simulator consists of three single polarization radiometers at frequencies of 19.35, 37.0 and 85.5 GHz which are capable of both Dicke Radiometer and Total Power

  20. A modified model for specular sea surface emissivity at microwave frequencies

    Microsoft Academic Search

    Sandra L. Cruz-Pol; Christopher S. Ruf

    2000-01-01

    Modifications to the L.A. Klein et al. model (1997) for specular ocean emissivity have recently been suggested by W.J. Ellison et al. (1996) in order to improve the performance at high microwave frequencies. The work presented in the present article tests both the original and modified models using a set of satellite and ground-based observations that is designed to eliminate

  1. Manifestations of Energetic Electrons with Anisotropic Distributions in Solar Flares. II. Gyrosynchrotron Microwave Emission

    Microsoft Academic Search

    Alexey A. Kuznetsov; Valentina V. Zharkova

    2010-01-01

    We investigate the spectra and polarization of the gyrosynchrotron microwave (MW) emission generated by anisotropic electron beams in the solar corona. The electron distributions are selected from the steady propagation\\/precipitation model of beam electrons obtained from the time-dependent solutions of the Fokker-Planck equation taking into account particle anisotropic precipitation into a converging magnetic tube while losing energy in collisions and

  2. 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.

  3. Highly sensitive beryllium detection with microwave plasma source atomic emission spectrometry

    Microsoft Academic Search

    Yongxuan Su; Zhe Jin; Yixiang Duan; Martin Koby; Vahid Majidi; Jose A Olivares; Stephen P Abeln

    2000-01-01

    A highly sensitive technique for beryllium determination using microwave induced plasma atomic emission spectrometry (MIP-AES) is explored in this work based on a self-assembled instrumental system. The analytical performance of this system for beryllium determination was examined using argon as working gas and an ultrasonic nebulization–desolvation system for solution sample introduction. Experimental operating parameters, such as working gas flow rate,

  4. Microwave induced plasma atomic emission spectrometry: a suitable detection system for the determination of volatile halocarbons

    Microsoft Academic Search

    Sofie Slaets; Frank Laturnus; Freddy C. Adams

    1999-01-01

    Microwave induced plasma atomic emission spectrometry (MIP-AES), a highly sensitive detection system for organometal compounds,\\u000a was coupled to an automated purge and trap gas chromatographic system for the determination of volatile halogenated hydrocarbons\\u000a in environmental water samples. Optimisation of the parameters affecting the injection and detection system led to relative\\u000a detection limits from 1 to 14 ng · L–1 for

  5. Characteristics of nebulizers for microwave induced plasma atomic emission spectrometry. II. Ultrasonic nebulizers

    NASA Astrophysics Data System (ADS)

    Jankowski, Krzysztof; Karmasz, Dorota; Ramsza, Andrzej; Reszke, Edward

    1997-10-01

    Ultrasonic nebulizers were designed and matched to low power microwave induced plasma operating conditions. The dependence of aerosol concentration on vibrational amplitude and operating temperature of the transducer as well as the carrier gas and sample flows has been studied. Optimal performance parameters of the nebulizer have been determined. Spectroscopic evaluation of analytical performance of nebulizers was carried out for several elements. The relationship between mechanical efficiency of the nebulizer and emission intensity was discussed.

  6. Use of microwave plasma torch atomic emission spectrometry for the determination of silicon

    Microsoft Academic Search

    Feng LiangHanqi; Hanqi Zhang; Qun Jin; Daxin Zhang; Yahu Lei; Qinhan Jin

    1997-01-01

    A method for the elimination of matrix effects was developed for the determination of trace amounts of silicon by microwave\\u000a plasma torch atomic emission spectrometry (MPT-AES). The sample solution was introduced into the MPT with a pneumatic nebulizer\\u000a (PN). When Ar was used as both carrier and support gas, a detection limit of 10.8 ng\\/ml was obtained. The precision was

  7. Recent Advances in Microwave Induced Plasma Atomic Emission Spectrometry with Okamoto-Cavity

    Microsoft Academic Search

    Kazuaki Wagatsuma

    2005-01-01

    Microwave induced plasmas with an Okamoto?cavity (Okamoto?cavity MIP) are noted as a new excitation source in atomic emission spectrometry. The Okamoto?cavity MIP can be sustained with various plasma gases, and can produce each stable plasma with a high robustness against loading of various types of samples. For example, the oxygen?containing MIP becomes an effective atomization and excitation source for direct

  8. Possible manifestation of large-scale transverse oscillations of coronal loops in solar microwave emission

    Microsoft Academic Search

    M. L. Khodachenko; K. G. Kislyakova; T. V. Zaqarashvili; A. G. Kislyakov; M. Panchenko; V. V. Zaitsev; O. V. Arkhypov; H. O. Rucker

    2011-01-01

    Aims: We interpret long-periodic (minutes) modulations detected in solar microwave emission during flaring events as signatures of large-scale transverse oscillations of coronal loops. Methods: Our data analysis method is based methodologically on a sliding-window Fourier transform combined with the Vigner-Wille technique. We analyze three different events where TRACE detected post-flare oscillating loops (on Mar. 23, 2000; Sep. 15, 2001; Sep.

  9. The MIDAS experiment: A prototype for the microwave emission of UltraHigh Energy Cosmic Rays

    Microsoft Academic Search

    M. Monasor; I. Alekotte; J. Alvarez-Muniz; X. Bertou; M. Bodgan; M. Bohacova; C. Bonifazi; W. Carvalho; J. F. Genat; P. Facal San Luis; E. Mills; B. Rouille d'Orfeuil; S. Wayne; L. C. Reyes; E. M. Santos; P. Privitera; C. Williams; E. Zas

    2010-01-01

    Recent measurements suggest that extensive air showers initiated by\\u000aultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the\\u000aelectromagnetic spectrum caused by the collisions of the free-electrons with\\u000athe atmospheric neutral molecules in the plasma produced by the passage of the\\u000ashower. Such emission is isotropic and could allow the detection of air showers\\u000awith 100%

  10. Microwave Emission and Plant Water Content: A Comparison between Field Measurements and Theory

    Microsoft Academic Search

    Paolo Pampaloni; Simonetta Paloscia

    1986-01-01

    Microwave radiation from a canopy cover depends primarily on the vegetation's thermal and dielectric properties; the latter are dependent on plant biometrical parameters and water content. Emission measurements carried out by means of ground-based X-and Ka-band radiometers have shown that crop coverage of soil can be detected through the spectral signatures of bare soil and vegetation. Moreover, measured brightness temperature

  11. Strong localization induced anomalous temperature dependence exciton emission above 300 K from SnO2 quantum dots

    NASA Astrophysics Data System (ADS)

    Pan, S. S.; Li, F. D.; Liu, Q. W.; Xu, S. C.; Luo, Y. Y.; Li, G. H.

    2015-05-01

    SnO2 quantum dots (QDs) are potential materials for deep ultraviolet (DUV) light emitting devices. In this study, we report the temperature and excitation power-dependent exciton luminescence from SnO2 QDs. The exciton emission exhibits anomalous blue shift, accompanied with band width reduction with increasing temperature and excitation power above 300 K. The anomalous temperature dependences of the peak energy and band width are well interpreted by the strongly localized carrier thermal hopping process and Gaussian shape of band tails states, respectively. The localized wells and band tails at conduction minimum are considered to be induced by the surface oxygen defects and local potential fluctuation in SnO2 QDs.

  12. 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...

  13. Erratum: A search for interstellar anthracene toward the Perseus anomalous microwave emission region

    Microsoft Academic Search

    S. Iglesias-Groth; A. Manchado; R. Rebolo; J. I. González Hernández; D. A. García-Hernández; D. L. Lambert

    2010-01-01

    We report the discovery of a new broad interstellar (or circumstellar) band\\u000aat 7088.8 +- 2.0 \\\\AA coincident to within the measurement uncertainties with\\u000athe strongest band of the anthracene cation (C$_{14}$H$_{10}$$^+$) as measured\\u000ain gas-phase laboratory spectroscopy at low temperatures (Sukhorukov et\\u000aal.2004). The band is detected in the line of sight of star Cernis 52, a likely\\u000amember

  14. A search for interstellar anthracene towards the Perseus anomalous microwave emission region

    Microsoft Academic Search

    S. Iglesias-Groth; A. Manchado; R. Rebolo; J. I. González Hernández; D. A. García-Hernández; D. L. Lambert

    2010-01-01

    We report the discovery of a new broad interstellar (or circumstellar) band at 7088.8 +\\/- 2.0 Å coincident to within the measurement uncertainties with the strongest band of the anthracene cation (C14H10+) as measured in gas-phase laboratory spectroscopy at low temperatures. The band is detected in the line of sight of star Cernis 52, a likely member of the very

  15. Fullerenes as carriers of extinction, diffuse interstellar bands and anomalous microwave emission

    Microsoft Academic Search

    Susana Iglesias-Groth

    2008-01-01

    According to semiempirical models, photoabsorption by fullerenes (single and multishell) could explain the shape, width and peak energy of the most prominent feature of the interstellar absorption, the UV bump at 2175 Å. Other weaker transitions are predicted in the optical and near-infrared providing a potential explanation for diffuse interstellar bands. In particular, we find that several fullerenes could contribute

  16. Observations of the microwave emission of Venus from 1. 3 to 3. 6 cm

    SciTech Connect

    Steffes, P.G.; Jenkins, J.M.; Klein, M.J. (Georgia Institute of Technology, Atlanta (USA) JPL, Pasadena, CA (USA))

    1990-03-01

    An account is given of the methodology as well as the results of coordinated Venus emission observations conducted at four wavelengths between 1.35 and 3.6 cm; the results are compared with other observations and with calculated mission spectra, with a view to suggestions that the microwave spectrum of Venus could be sensitive to the subcloud abundance of such constituents as SO2 and gaseous H2SO4. The observed emission spectrum is consistent with an average subcloud abundance of gaseous H2SO4 in equatorial and midlatitude regions of about 5 ppm. An upper limit is established for the subcloud SO2 abundance. 19 refs.

  17. Simulations of gyrosynchrotron microwave emission from an oscillating magnetic loop

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Alexey; Reznikova, Veronika; Van Doorsselaere, Tom; Antolin, Patrick

    Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by MHD oscillations of flaring loops which modulate the radio emission via variations of the magnetic field and electron concentration. We perform numerical simulations of gyrosynchrotron radiation from a toroidal-shaped magnetic loop containing sausage-mode MHD oscillations. Different parameters of the loop and MHD oscillations and different loop orientations are considered. The simulation results are compared with the observations of the Nobeyama Radioheliograph.

  18. 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.

  19. A parameterization of effective soil temperature for microwave emission

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A parameterization of effective soil temperature is discussed, which when multiplied by the emissivity gives the brightness temperature in terms of surface (T sub o) and deep (T sub infinity) soil temperatures as T = T sub infinity + C (T sub o - T sub infinity). A coherent radiative transfer model and a large data base of observed soil moisture and temperature profiles are used to calculate the best-fit value of the parameter C. For 2.8, 6.0, 11.0, 21.0 and 49.0 cm wavelengths. The C values are respectively 0.802 + or - 0.006, 0.667 + or - 0.008, 0.480 + or - 0.010, 0.246 + or - 0.009, and 0,084 + or - 0.005. The parameterized equation gives results which are generally within one or two percent of the exact values.

  20. 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.

  1. Anomalous non-magnetic high field loss peak for a high Q copper TE011 microwave cavity

    Microsoft Academic Search

    Liam Kilcommons; Falko Kuester; Carl Patton

    2009-01-01

    Recent off resonance magnetic loss measurements with high quality factor (Q) TE011 cavities have revealed the presence of a small anomalous loss peak at high field overlying the usual magnetic response. Precision measurements of the cavity Q vs. field by the ABA metrological substitution method for a special 99.99% pure OFHC (oxygen free high conductivity) copper cavity have now confirmed

  2. 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.

  3. Regionalization of Methane Emissions in the Amazon Basin with Multi-temporal Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Hess, L. L.; Forsberg, B. R.; Hamilton, S. K.; Novo, E. M.

    2002-12-01

    Remote sensing of the Amazon basin with passive and active microwave techniques were applied to determine the temporally varying extent of inundation and associated vegetation, and used in conjunction with field measurements to calculate regional rates of methane emission from wetlands to the atmosphere. Monthly inundation areas were derived from analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (1979 -87) for the mainstem Amazon floodplain in Brazil, the Llanos de Moxos (Beni and Mamore rivers) in Bolivia, the Bananal Island (Araguaia River) and Roraima savannas. Data from the Japanese Earth Resources Satellite-1, L-band synthetic aperture radar were used to determine inundation and wetland vegetation for Amazon basin less than 500 m above sea level at high water (May-June 1996) and low water (October 1995). Although all the measurements of methane emission from aquatic habitats have been performed in the deeply inundated, central basin in open water, flooded forests or floating macrophytes, our basin-wide remote sensing has revealed large areas of seasonally flooded savannas. Therefore, improvements in basin-wide estimates of methane emission will require field studies in wetlands such as those in Bolivia, Roraima and the Bananal.

  4. A model describing the microwave emission from a multi-layer snowpack at 37 GHz

    NASA Technical Reports Server (NTRS)

    Abdelrazik, M.; Ulaby, F.; Stiles, H.

    1981-01-01

    A multilayer emission model is described and applied to emission measurements obtained at 37 GHz and H polarization using a microwave radiometer attached to a truck-mounted boom in Steamboat Springs, Colorado in 1977. Estimated absorption and scattering coefficients and their dependence on wetness were obtained using calculated values of the dielectric constant at 37 GHz along with the model. It was found that the scattering coefficient is comparable in value to the absorption coefficient for dry snow however, the absorption coefficient increases linearly with increasing snow wetness while the scattering coefficient decreases linearly with increasing wetness. The emission from each layer of the snowpack was also calculated using the estimated coefficients. It is shown that for dry snow, the ground underneath the snowpack contributes about 45% of all measured emission while the rest is due to emission from all the layers within the snowpack. When the wetness of the top 5 cm layer of snowpack increases to about 2% by volume, this top 5 cm snowlayer contributes more than 90% of all the measured emission.

  5. Determination of small amounts of palladium in wastes from reworking of spent catalysts by microwave induced plasma atomic emission spectrometry

    Microsoft Academic Search

    K. Jankowski

    1995-01-01

    Microwave induced plasma atomic emission spectrometry (MIP-AES) was used for analytical control of reworking of catalysts. Palladium was determined in plant wastes after acid digestion in open systems or systems under pressure. The conditions for introduction of analyte solution using ultrasonic nebulisation and excitation of palladium in the low-power argon microwave plasma sustained in the TM010 Beenakker type resonator were

  6. 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.

  7. 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.

  8. 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.

  9. Synchrotron Emission from Hot Accretion Flows and the Cosmic Microwave Background Anisotropy

    E-print Network

    Rosalba Perna; Tiziana Di Matteo

    2000-05-11

    Current estimates of number counts of radio sources in the frequency range where the most sensitive Cosmic Microwave Background (CMB) experiments are carried out significantly under-represent sources with strongly inverted spectra. Hot accretion flows around supermassive black holes in the nuclei of nearby galaxies are expected to produce inverted radio spectra by thermal synchrotron emission. We calculate the temperature fluctuations and power spectra of these sources in the Planck Surveyor 30 GHz energy channel, where their emission is expected to peak. We find that their potential contribution is generally comparable to the instrumental noise, and approaches the CMB anisotropy level at small angular scales. Forthcoming CMB missions, which will provide a large statistical sample of inverted-spectra sources, will be crucial for determining the distribution of hot accretion flows in nearby quiescent galactic nuclei. Detection of these sources in different frequency channels will help constrain their spectral characteristics, hence their physical properties.

  10. 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

  11. [Peak-width quantitation for flow-injection microwave plasma torch-atomic emission spectrometry].

    PubMed

    Li, Yong-sheng; Zhao, Bo; Sun, Xu-hui

    2009-09-01

    A peak-width quantitation method for flow-injection microwave plasma torch atomic emission spectrometry was proposed. Sensitivity and linearity of the peak-width quantitation were investigated under different emission intensities. Recoveries of Zn2+, Cu2+ and Ag+ existing in various matrix were determined by using the peak-width quantitation, and were compared with the results obtained by the peak-height method. The results indicated that the peak-width quantitation can efficiently remove matrix interference in the FI-MPT-AES system, and expand its linear determination range. The peak-width quantitation (recovery: 92%-107%) surpasses conventional peak-height method (recovery: 61.3%-122%). Optimized determination conditions were as follows: the sampling volume was 350 mL, the flow rate of the carrier was 1.5 mL x min(-1), the power of microwave was 110 W, the flow rates of the carrier gas and working gas (argon) were 1.4 and 0.4 L x min(-1), respectively. PMID:19950675

  12. On detection of the thermophysical state of landfast first-year sea ice using in-situ microwave emission during spring melt

    Microsoft Academic Search

    Byong Jun Hwang; Alexandre Langlois; David G. Barber; Timothy N. Papakyriakou

    2007-01-01

    In this study we examine the critical linkages between thermophysical properties and microwave emissions of landfast snow-covered first-year sea ice during spring melt. For this we analyzed the temporal evolution of radiation fluxes, electro-thermophysical properties and microwave emissions, and perform model simulations to evaluate the observations. The results show five major microwave signature events: brine-rich, blowing snow, melt onset, the

  13. 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.

  14. 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.

  15. Mid-Infrared and Visible Photometry of Galaxies: Anomalously Low Polycyclic Aromatic Hydrocarbon Emission from Low-Luminosity Galaxies

    NASA Astrophysics Data System (ADS)

    Hogg, David W.; Tremonti, Christy A.; Blanton, Michael R.; Finkbeiner, Douglas P.; Padmanabhan, Nikhil; Quintero, Alejandro D.; Schlegel, David J.; Wherry, Nicholas

    2005-05-01

    The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC) near- and mid-infrared imaging data partially overlap the Sloan Digital Sky Survey (SDSS), with 313 visible-selected (r<17.6 mag) SDSS main sample galaxies in the overlap region. The 3.5 and 7.8 ?m properties of the galaxies are investigated in the context of their visible properties, where the IRAC [3.5] magnitude primarily measures starlight and the [7.8] magnitude primarily measures polycyclic aromatic hydrocarbon (PAH) emission from the interstellar medium. As expected, we find a strong inverse correlation between [3.5]-[7.8] and visible color; galaxies red in visible colors (``red galaxies'') tend to show very little dust and molecular emission (low PAH-to-star ratios), and galaxies blue in visible colors (``blue galaxies,'' i.e., star-forming galaxies) tend to show large PAH-to-star ratios. Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by dust lanes. Simple attenuation corrections inferred in the visible bring the visible colors of these galaxies in line with those of face-on disks; i.e., PAH emission is closely related to attenuation-corrected star formation rates inferred in the visible. Blue galaxies with anomalously low PAH-to-star ratios are all low-luminosity star-forming galaxies. There is some weak evidence in this sample that the deficiency in PAH emission for these low-luminosity galaxies may be related to emission-line metallicity.

  16. A Review of Microwave Plasma Sources in Atomic Emission Spectrometry: Literature from 1985 to the Present

    Microsoft Academic Search

    A. E. Croslyn; B. W. Smith; J. D. Winefordner

    1997-01-01

    Microwave plasmas have been used as sources for atomic spectroscopy since the 1970s. Several common forms of this plasma source exist, including the microwaveinduced plasma, the capacitively coupled microwave plasma, the surface-wave or surfatron plasma, the microwave plasma torch, and some other unique designs. Although not as popular as the inductively coupled plasma, microwave plasmas offer the advantage of lower

  17. The behavior of molecules in microwave-induced plasmas studied by optical emission spectroscopy. 1. Plasmas at atmospheric pressure

    Microsoft Academic Search

    E. A. H. Timmermans; J. Jonkers; I. A. J. Thomas; A. Rodero; M. C. Quintero; A. Sola; A. Gamero; Mullen van der JJAM

    1998-01-01

    The behavior of molecules in different atmospheric microwave-induced plasmas (MIPs) has been studied by means of optical emission spectroscopy. This is in order to obtain more insight into molecular processes in plasmas and to investigate the feasibility of emission spectroscopy for the analysis of molecular compounds in gases, e.g. flue gases. Various molecular species (i.e. N2, CO2, H2O, SF6 and

  18. Determination of arsenic and antimony by microwave plasma atomic emission spectrometry coupled with hydride generation and a PTFE membrane separator

    Microsoft Academic Search

    Zhenbin Gong; Wing Fat Chan; Xiaoru Wang; Frank S.-C Lee

    2001-01-01

    The performance of a microwave plasma torch (MPT) discharge atomic emission spectrometry (AES) system directly coupled with hydride generation (HG) for the determination of As and Sb has been studied. The argon MPT system can sustain a stable plasma over a wide range of carrier and support gas flow rates with optimum performance at 250 and 1450mlmin?1, respectively. The presence

  19. Investigations on the on-line determination of metals in air flows by capacitively coupled microwave plasma atomic emission spectrometry

    Microsoft Academic Search

    M. Seelig; J. A. C Broekaert

    2001-01-01

    Plasma optical emission spectrometry with a capacitively coupled microwave plasma (CMP) operated with air has been investigated with respect to its possibilities for real-time environmental monitoring of combustion processes. The unique feature is the possibility to operate the CMP with air as working gas, as is usually the case in exhaust gases of combustion processes. The CMP also is shown

  20. Subnanogram Determination of Inorganic and Organic Mercury by Helium-Microwave Induced Plasma-Atomic Emission Spectrometry

    Microsoft Academic Search

    K. Fukushi; S. N. Willie; R. E. Sturgeon

    1993-01-01

    Inorganic and organic mercury were determined by helium-microwave induced plasma-atomic emission spectrometry following cold vapor generation. Whereas only inorganic mercury was reduced by stannous ion in an acidic medium, both inorganic and organic mercury (total mercury) were reduced by stannous ion in the presence of cupric ion in a basic medium. Organic mercury was determined as the difference between total

  1. 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.

  2. Microwave emission from relativistic electron beams. Final report, 1 November 1983-31 October 1988

    SciTech Connect

    Bekefi, G.

    1989-03-01

    Profile modification by optical guiding in a Raman free-electron laser operating at microwave frequencies was studied experimentally. A cyclotron autoresonance maser (CARM) amplifier was designed, built, and tested. This CARM operates at 35 GHz with a power output of 10 MW and an efficiency of 3%. Observations of Field Profile Modifications in a Raman Free-Electron Laser Amplifier: The author reports measurements of the spatial distribution of the RF electric-field intensities and phases induced in a free-electron laser amplifier operating in the collective (Raman) regime. The studies are carried out at a microwave frequency of about 10 GHz in a FEL using a mildly relativistic electron beam of about 200 keV energy and 1 - 4A current. The probing of the ponderomotive (space charge) and the electromagnetic waves is accomplished by means of small movable electric dipole antennas inserted into the interaction region. A 35-GHz Cyclotron Autoresonance Maser Amplifier: studies of a cyclotron autoresonance maser are presented. The measurements are carried out at a frequency of 35 GHz using a mildly relativistic electron beam (1.5 MeV, 260 A) generated by a field-emission electron gun followed by an emittance selector that removes the outer, hot electrons. Perpendicular energy is imparted to the electrons by means of a bifilar helical wiggler. Measurements give a small signal gain of 90 dB/m and a saturated power output of 10 MW. The corresponding electronic efficiency is 3%. Computer simulations are also presented.

  3. Investigations on laser ablation microwave induced plasma atomic emission spectrometry using polymer samples

    NASA Astrophysics Data System (ADS)

    Leis, F.; Bauer, H. E.; Prodan, L.; Niemax, K.

    2001-01-01

    The potential of laser ablation-microwave induced plasma-atomic emission spectrometry (LA-MIP-AES) for the analysis of plastic materials has been investigated. A Nd/YAG laser, operated in its fundamental mode at 1064 nm, was used to ablate small amounts of various plastics. The sample atoms were transported and excited in a closely neighbored continuously running microwave induced plasma (MIP) operated in argon or helium at reduced pressure. A 0.5-m échelle spectrometer, equipped with an intensified charge coupled device (ICCD) as a detector was used for recording the spectra. The amount of ablated material was found to be strongly dependent on the matrix (10-190 ng/shot). Signals for some metals often used as additives in polymers (Al, Ca, Cu, Sb, Ti) and for the elements F, Cl, Br, J, and P in various polymers were recorded in the spectral range 250-840 nm. The estimated detection limits were found to be in the range 0.001-0.08% for metals and 0.05-0.7% for non-metals. Spectral lines of fluorine and iodine could only be measured in the helium MIP. For high concentrations of chlorine and carbon in the samples (polyvinylchloride), a memory effect was observed.

  4. A new low-power microwave plasma source using microstrip technology for atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Bilgic, A. M.; Engel, U.; Voges, E.; Kückelheim, M.; Broekaert, J. A. C.

    2000-02-01

    A new low-power, compact microwave-induced plasma source for applications in atomic emission spectrometry at atmospheric pressure using microstrip technology is described. The gas channel of about 1 mm2 is integrated in a fused silica dielectric wafer. The microstrip transmission lines are fabricated by sputtering and electro-plating. For example, a unit operates at an input power of 15 W with an argon gas flow of about 500 ml min-1 at atmospheric pressure. Rotational (OH) and excitation (Fe) temperatures of 650 K and 8000 K, respectively, were measured at these conditions. The emitted radiation can be taken up by an optical fibre positioned in the plasma-gas channel thus enabling an axial observation and coupling to a miniaturized spectrometer. The first devices showed an operation time of at least several hundred hours. Further investigations will lead to even smaller dimensions and lower power consumption and open the way for integrated microwave plasma sources with low detection limits as integrable parts of miniaturized total analytical systems applications.

  5. 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.

  6. Atomic emission spectrometry of solid samples with laser vaporization-microwave induced plasma system

    SciTech Connect

    Ishizuka, T.; Uwamino, Y.

    1980-01-01

    A laser vaporization-microwave induced plasma system was used for the determination of various elements in solid samples such as brass, steel, and aluminum alloy. The emission signals of Al, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Tl, and Zn were traced with an oscilloscope, and those elements were determined with high-speed peak-holder and integrator. Precision (relative standard deviation) was 1.2% to 13.8% for the peak-height method, and 2.3% to 12.1% for the peak-area method. The detection limits in the solid samples ranged from 0.9 ppM (0.7 pg) for Zn in aluminum alloy to 22 ppM (20 pg) for Mo in steel. 9 figures, 2 tables.

  7. Thermospray nebulizer as sample introduction technique for microwave plasma torch atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Yang, Chenglong; Zhuang, Zhixia; Tu, Yi; Yang, Pengyuan; Wang, Xiaoru

    1998-09-01

    A thermospray nebulizer was used as a sample introduction device for microwave plasma torch (MPT) atomic emission spectrometry (AES). Experimental parameters, including the power supplied to the MPT, the flow rates of support and carrier gases, the observation height, the sample uptake rate, the thermospray working temperature, the temperature of the aerosol spray chamber and cooling water were optimized. Under optimum conditions, the relative standard deviation (RSD) of 10 measurements for 21 elements is in the range 0.3-2.0%. The detection limits were improved in comparison with the ultrasonic nebulizer as sample introduction technique for MPT-AES. The inclusion of 20% methanol into the MPT showed there is no effect on the stability of MPT discharge. The technique can thus be held to have the potential for interface to reverse-phase HPLC systems.

  8. Snow-cover environmental monitoring and assessment in Northeast China using passive microwave emission models.

    PubMed

    Song, Kaishan; Zhang, Yuanzhi

    2008-05-01

    In this study, we present the application of the passive microwave emission models to snow-cover environment monitoring and assessment in Northeast China. The study employs the radiative transfer function and strong fluctuation theory to develop the models. We used the exponential form of a spherical symmetric correlation function to describe random permittivity fluctuations. From strong fluctuation, we then obtained the phase matrix and extinction coefficients of snow-packs for the spherical symmetric correlation function. We also used the vector radiative transfer formula for the layer of a random medium by solving Gaussian quadrature and eigen analysis. By comparing the brightness temperatures at 5, 10.7, 18, and 37 GHz, the modelling results agreed with experimental data of dry-snow physical parameters as measured in the fieldwork. PMID:17671847

  9. Development of a resonant-type microwave reactor and its application to the synthesis of positron emission tomography radiopharmaceuticals.

    PubMed

    Kimura, Hiroyuki; Yagi, Yusuke; Ohneda, Noriyuki; Odajima, Hiro; Ono, Masahiro; Saji, Hideo

    2014-10-01

    Microwave technology has been successfully applied to enhance the effectiveness of radiolabeling reactions. The use of a microwave as a source of heat energy can allow chemical reactions to proceed over much shorter reaction times and in higher yields than they would do under conventional thermal conditions. A microwave reactor developed by Resonance Instrument Inc. (Model 520/521) and CEM (PETWave) has been used exclusively for the synthesis of radiolabeled agents for positron emission tomography by numerous groups throughout the world. In this study, we have developed a novel resonant-type microwave reactor powered by a solid-state device and confirmed that this system can focus microwave power on a small amount of reaction solution. Furthermore, we have demonstrated the rapid and facile radiosynthesis of 16?-[(18)F]fluoroestradiol, 4-[(18)F]fluoro-N-[2-(1-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinylbenzamide, and N-succinimidyl 4-[(18)F]fluorobenzoate using our newly developed microwave reactor. PMID:25294422

  10. WMAP 3yr data with the CCA: anomalous emission and impact of component separation on the CMB power spectrum

    E-print Network

    A. Bonaldi; S. Ricciardi; S. Leach; F. Stivoli; C. Baccigalupi; G. De Zotti

    2007-07-24

    The Correlated Component Analysis (CCA) allows us to estimate how the different diffuse emissions mix in CMB experiments, exploiting also complementary information from other surveys. It is especially useful to deal with possible additional components. An application of CCA to WMAP maps assuming that only the canonical Galactic emissions are present, highlights the widespread presence of a spectrally flat "synchrotron" component, largely uncorrelated with the synchrotron template, suggesting that an additional foreground is indeed required. We have tested various spectral shapes for such component, namely a power law as expected if it is flat synchrotron, and two spectral shapes that may fit the spinning dust emission: a parabola in the logS - log(frequency) plane, and a grey body. Quality tests applied to the reconstructed CMB maps clearly disfavour two of the models. The CMB power spectra, estimated from CMB maps reconstructed exploiting the three surviving foreground models, are generally consistent with the WMAP ones, although at least one of them gives a significantly higher quadrupole moment than found by the WMAP team. Taking foreground modeling uncertainties into account, we find that the mean quadrupole amplitude for the three "good" models is less than 1 sigma below the expectation from the standard LambdaCDM model. Also the other reported deviations from model predictions are found not to be statistically significant, except for the excess power at l~40. We confirm the evidence for a marked North-South asymmetry in the large scale (l < 20) CMB anisotropies. We also present a first, albeit preliminary, all-sky map of the "anomalous" component.

  11. Microwave emissivity of fresh water ice--Lake ice and Antarctic ice pack--Radiative transfer simulations versus satellite radiances

    E-print Network

    Mills, Peter

    2012-01-01

    Microwave emissivity models of sea ice are poorly validated empirically. Typical validation studies involve using averaged or stereotyped profiles of ice parameters against averaged radiance measurements. Measurement sites are rarely matched and even less often point-by-point. Because of saline content, complex permittivity of sea ice is highly variable and difficult to predict. Therefore, to check the validity of a typical, plane-parallel, radiative-transfer-based ice emissivity model, we apply it to fresh water ice instead of salt-water ice. Radiance simulations for lake ice are compared with measurements over Lake Superior from the Advanced Microwave Scanning Radiometer on EOS (AMSR-E). AMSR-E measurements are also collected over Antarctic icepack. For each pixel, a thermodynamic model is driven by four years of European Center for Medium Range Weather Forecasts (ECMWF) reanalysis data and the resulting temperature profiles used to drive the emissivity model. The results suggest that the relatively simple ...

  12. Spatial Variability of Barrow-Area Shore-Fast Sea Ice and Its Relationships to Passive Microwave Emissivity

    NASA Technical Reports Server (NTRS)

    Maslanik, J. A.; Rivas, M. Belmonte; Holmgren, J.; Gasiewski, A. J.; Heinrichs, J. F.; Stroeve, J. C.; Klein, M.; Markus, T.; Perovich, D. K.; Sonntag, J. G.; Tape, K.

    2006-01-01

    Aircraft-acquired passive microwave data, laser radar height observations, RADARSAT synthetic aperture radar imagery, and in situ measurements obtained during the AMSR-Ice03 experiment are used to investigate relationships between microwave emission and ice characteristics over several space scales. The data fusion allows delineation of the shore-fast ice and pack ice in the Barrow area, AK, into several ice classes. Results show good agreement between observed and Polarimetric Scanning Radiometer (PSR)-derived snow depths over relatively smooth ice, with larger differences over ridged and rubbled ice. The PSR results are consistent with the effects on snow depth of the spatial distribution and nature of ice roughness, ridging, and other factors such as ice age. Apparent relationships exist between ice roughness and the degree of depolarization of emission at 10,19, and 37 GHz. This depolarization .would yield overestimates of total ice concentration using polarization-based algorithms, with indications of this seen when the NT-2 algorithm is applied to the PSR data. Other characteristics of the microwave data, such as effects of grounding of sea ice and large contrast between sea ice and adjacent land, are also apparent in the PSR data. Overall, the results further demonstrate the importance of macroscale ice roughness conditions such as ridging and rubbling on snow depth and microwave emissivity.

  13. Direct solid atomic emission spectrometric analysis of metal samples by an argon microwave plasma torch coupled to spark ablation

    NASA Astrophysics Data System (ADS)

    Engel, U.; Kehden, A.; Voges, E.; Broekaert, J. A. C.

    1999-09-01

    Spark ablation has been combined to microwave plasma torch atomic emission spectrometry for the direct analysis of compact metallic samples. The material is ablated by a medium voltage spark (450 V, 370 Hz) in a point-to-plane configuration and swept into a 100-W, 2.45-GHz argon microwave discharge. The microwave plasma is observed end-on and the radiation analysed with a polychromator. The detection limits for Fe, Ni, Pb and Sn in brass, Cr, Cu, Ni, Mn, Mo, Si and V in steel and Cu, Fe, Mg, Mn, Si and Zn in aluminium with the microwave plasma torch in the case of measurements with a polychromator are in the ?g/g range and by a factor of up to 20 higher than those obtained with spark ablation coupled to inductively coupled plasma atomic emission spectrometry using a high resolution sequential spectrometer. The stability of the emission signal depends on the element studied and relative standard deviations usually are between 0.5 and 3.5%. In the case of low-alloy steels, the linearity and the precision of the calibration could be improved by internal standardisation. Several elements (Cr, Cu, Ni, Si and V) could be determined in a steel sample (BAS SS 410/1) with high accuracy and precision.

  14. Anomalous X-Ray emission in GRB060904B: a Nickel line?

    E-print Network

    R. Margutti; A. Moretti; F. Pasotti; S. Campana; G. Chincarini; S. Covino; C. Guidorzi; P. Romano; G. Tagliaferri

    2007-12-10

    The detection of an extra component in GRB060904B X-ray spectra in addition to the standard single power-law behaviour has recently been reported in the literature. This component can be fit with different models; in particular the addition of a spectral line provides the best representation.In this paper we investigate the physical properties that the surrounding medium must have in order to produce a spectral feature that can explain the detected emission. We analyse and discuss how and if the detected spectral excess fits in different theoretical models developed to explain the nature of line emission during the afterglow phase of Gamma-Ray Bursts (GRBs). Trasmission and reflection models have been considered. Given the high value (>>1) of the Thomson optical depth, the emission is likely to arise in a reflection scenario. Within reflection models, the external reflection geometry fails to predict the observed luminosity. On the contrary, the detected feature can be explained in a funnel scenario with typical opening angle theta of 5 degrees, Nickel mass of the order of 0.1 M_o and T=10^6 K. For theta=20 degrees, assuming the reprocessing material to be the SN shell, the detected emission implies a Nickel mass of 0.4 M_o at T=10^7 K and a metallicity 10 times the solar value. If the giant X-ray flare that dominates the early XRT light curve is identified with the ionizing source, the SN expansion began 3000 s before the GRB event.

  15. Nonequilibrium microwave emission due to tunnel injection of quasiparticles into a high-Tc Bi2Sr2CaCu2Oy superconductor

    Microsoft Academic Search

    I. Iguchi; K. Lee; E. Kume; T. Ishibashi; K. Sato

    2000-01-01

    Nonequilibrium microwave emission due to tunnel injection of quasiparticles into a high-Tc Bi2Sr2CaCu2Oy (Bi2212) superconducting thin film using an Au\\/I\\/Bi2212 tunnel junction is reported. The microwaves were detected by a superheterodyne-mixer technique at a receiver frequency of 47 GHz. With increasing the injection current, the emitted microwave intensity increased almost linearly at relatively low temperatures, in qualitative agreement with the

  16. Emission Properties of Compact Antenna-Excited SuperHigh Pressure Mercury Microwave Discharge Lamps

    Microsoft Academic Search

    Takafumi Mizojiri; Yukihiro Morimoto; Masashi Kando

    2007-01-01

    A compact high-intensity microwave discharge lamp and ignition system have been investigated using a couple of antennas and a solid-state microwave generator. It is found that the antenna-excited microwave discharge lamps can sustain mercury discharges at pressures higher than 100 atm with 2.45 GHz microwave power lower than 80 W, and that a stable plasma column is generated isolated from

  17. ANOMALOUS SILICATE DUST EMISSION IN THE TYPE 1 LINER NUCLEUS OF M81

    SciTech Connect

    Smith, Howard A.; Ashby, M. L. N.; Fazio, G. G.; Huang, J.-S.; Marengo, M.; Wang, Z.; Willner, S.; Zezas, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Li, Aigen; Li, M. P.; Koehler, M. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Spinoglio, L. [Istituto di Fisica dello Spazio Interplanetario, CNR, via Fosso del Cavaliere, 100, I-00133 Rome (Italy); Wu, Y. L., E-mail: hsmith@cfa.harvard.ed, E-mail: lia@missouri.ed [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91101 (United States)

    2010-06-10

    We report the detection and successful modeling of the unusual 9.7 {mu}m Si-O stretching silicate emission feature in the type 1 (i.e., face-on) LINER nucleus of M81. Using the Infrared Spectrograph (IRS) instrument on Spitzer, we determine the feature in the central 230 pc of M81 to be in strong emission, with a peak at {approx}10.5 {mu}m. This feature is strikingly different in character from the absorption feature of the galactic interstellar medium, and from the silicate absorption or weak emission features typical of galaxies with active star formation. We successfully model the high signal-to-noise ratio IRS spectra with porous silicate dust using laboratory-acquired mineral spectra. We find that the most probable fit uses micron-sized, porous grains of amorphous silicate and amorphous carbon. In addition to silicate dust, there is weak polycyclic aromatic hydrocarbon (PAH) emission present (particularly at 11.3 {mu}m, arising from the C-H out-of-plane bending vibration of relatively large PAHs of {approx}500-1000 C atoms) whose character reflects the low-excitation active galactic nucleus environment, with some evidence that small PAHs of {approx}100-200 C atoms (responsible for the 7.7 {mu}m C-C stretching band) in the immediate vicinity of the nucleus have been preferentially destroyed. Analysis of the infrared fine structure lines confirms the LINER character of the M81 nucleus. Four of the infrared H{sub 2} rotational lines are detected and fit to an excitation temperature of T {approx} 800 K. Spectral maps of the central 230 pc in the [Ne II] 12.8 {mu}m line, the H{sub 2} 17 {mu}m line, and the 11.3 {mu}m PAH C-H bending feature reveal arc- or spiral-like structures extending from the core. We also report on epochal photometric and spectroscopic observations of M81, whose nuclear intensity varies in time across the spectrum due to what is thought to be inefficient, sub-Eddington accretion onto its central black hole. We find that, contrary to the implications of earlier photometry, the nucleus has not varied over a period of two years at these infrared wavelengths to a precision of about 1%.

  18. Direct determination of trace amounts of sodium in water-soluble organic pharmaceuticals by microwave induced plasma atomic emission spectrometry

    Microsoft Academic Search

    Krzysztof Jankowski

    2001-01-01

    The direct determination of trace sodium by microwave induced plasma atomic emission spectrometry (MIP-AES) in water-soluble organic substances utilized in pharmaceutical preparations was developed. No decomposition of the organic constituents was required. Samples were dissolved with water and introduced to the plasma after ultrasonic nebulization without desolvation. A limit of detection (3?) of 0.91–3.0 ng ml?1 was obtained under experimental

  19. Determination of lead in steel by high power nitrogen microwave induced plasma atomic emission spectrometry coupled with hydride generation technique

    Microsoft Academic Search

    Akihiro Matsumotoa; Taketoshi Nakahara

    2004-01-01

    As a new excitation source for atomic emission spectrometry (AES), an annular-shape d high power nitrogen microwave induced plasma (N2-MIP) produced at atmospheric pressure by an Okamoto cavity, which is a new cavity-torch arrangement able to produce a doughnut-shape d plasma, has been used for the determination of tin in steels with the hydride generation method. Under the optimized experimental

  20. Direct, Continuous Hydride Generation Coupled with Microwave Induced Plasma-Atomic Emission Spectrometry for the Determination of Selenium

    Microsoft Academic Search

    Kin C. Ng; Xia-Xiu Xu; Michael J. Brechmann

    1989-01-01

    Selenium is determined by atomic emission technique with microwave induced helium plasma as the excitation source. A continuous hydride generation system using a peristaltic pump, an effective serpentine hydride generator and a gas-liquid separator is developed and interfaced to the He-plasma. The selenium hydride and the reaction by-products are carried directly and continuously by the He carrier gas (0.6 L\\/min)

  1. Characterization of multicapillary gas chromatography–microwave-induced plasma atomic emission spectrometry for the expeditious analysis for organometallic compounds

    Microsoft Academic Search

    Isaac Rodriguez Pereiro; Andrzej Wasik; Ryszard ?obi?ski

    1998-01-01

    Multicapillary column gas chromatography (MC-GC)–microwave-induced plasma atomic emission spectrometry (MIP-AES) is evaluated for fast speciation analysis of organometallic compounds. In situ derivatized organomercury, organotin and organolead compounds are separated isothermally within several seconds instead of several minutes required by the conventional procedures. Neither the resolution nor the sample capacity are sacrificed compared with conventional capillary GC with oven temperature gradient

  2. Solidphase microextraction–capillary gas chromatography combined with microwave-induced plasma atomic-emission spectrometry for selenite determination

    Microsoft Academic Search

    Emmanouil Dimitrakakis; Christina Haberhauer-Troyer; Yo Abe; Maria Ochsenkühn-Petropoulou; Erwin Rosenberg

    2004-01-01

    The use of solid-phase microextraction (SPME) with gas chromatography coupled to microwave-induced plasma atomic-emission detection (GC–MIP-AED) is described for selenite [Se(IV)] speciation. Aqueous standards were derivatised with sodium tetraethyl- or tetrapropylborate and extracted by SPME. Headspace extraction of the ethyl and propyl derivatives was studied. Relevant experimental conditions were optimised, including conditions for derivatisation and extraction and those of gas

  3. Determination of polychlorinated biphenyls in biotic matrices using gas chromatography-microwave-induced plasma atomic emission spectrometry

    Microsoft Academic Search

    Jana Hajšlová; Petr Cuhra; Milan Kempný; Jan Poustka; Kate?ina Holadová; Vladimír Kocourek

    1995-01-01

    Basic parameters associated with practical application of gas chromatography coupled with microwave-induced plasma atomic emission spectrometric detection GC-MIP-AED in the determination of seven “indicator” polychlorinated biphenyls (PCBs) in biotic matrices were evaluated. The detection limit for chlorine (Cl-479) was found to be 0.54 pg\\/s. Under the conditions used for sample analysis (1 ?l of purified extract injected into the GC-MIP-AED

  4. Flow-injection on-line column preconcentration for low powered microwave plasma torch atomic emission spectrometry

    Microsoft Academic Search

    Dongmei Ye; Hanqi Zhang; Qinhan Jin

    1996-01-01

    This paper describes an improvement in detection capability of microwave plasma torch atomic emission spectrometry by using a flow-injection on-line column preconcentration system. The analytical performances of Cd, Cu, Mn and Zn were studied. The analytes were preconcentrated with a thiol resin. The preconcentration period, the pH of the sample solution and the HCl concentration in the eluant were examined

  5. A novel fast-scanning microwave heterodyne radiometer system for electron cyclotron emission measurements in the HT7 superconducting tokamak

    Microsoft Academic Search

    S. Y. Zhang; V. Poznyak; E. Ploskirev; D. Kalupin; Y. X. Wan; J. K. Xie; J. R. Luo; J. G. Li; G. L. Kuang; X. Gao; X. D. Zhang; B. N. Wan; K. J. Wang; J. S. Mao; X. Z. Gong; P. J. Qin

    2000-01-01

    Two sets of fast-scanning microwave heterodyne radiometer receiver systems employing backward-wave oscillators in the 78-118 GHz and 118-178 GHz ranges were developed for electron cyclotron emission measurements (ECE) on the HT-7 superconducting tokamak. The double-sideband radiometer in the 78-118 GHz range measures 16 ECE frequency points with a scanning period of 0.65 ms. The novel design of the 2 mm

  6. 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

  7. X-radiation (E > 10keV), H? and microwave emission during the impulsive phase of solar flares

    Microsoft Academic Search

    Joan A. Vorpahl

    1972-01-01

    A study has been made of the variation in hard (E? 10 keV) X-radiation, Ha 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, i.e., trise ~ exp (0.87 d). The impulsive phase is also marked by an abrupt, very intense increase in Ha

  8. Long period oscillations of microwave emission of solar active regions: observations with NoRH and SSRT

    Microsoft Academic Search

    I. A. Bakunina; V. E. Abramov-Maximov; S. V. Lesovoy; K. Shibasaki; A. A. Solov'ev; Yu. V. Tikhomirov

    2009-01-01

    In this work we present the first results of study and comparison of the parameters of quasi-periodic long-term oscillations of microwave emission of large (>0.7 arcmin) sunspots as a result of simultaneous observations with two radioheliographs - NoRH (17 GHz) and Siberian Solar Radio Telescope (SSRT) (5.7 GHz) with 1 minute cadence. Radioheliographs have been working with quite large time

  9. Microwave emission due to anisotropic quasiparticle injection into an ErBa2Cu3Oy superconductor

    Microsoft Academic Search

    Kiejin Lee; Eiji Kume; Hitoshi Yamaguchi; Hiroyuki Arie; Wan Wang; Ienari Iguchi

    1999-01-01

    We report the observation of microwave emission and the dc measurements on tunnel injection of quasiparticles into a ErBa2 Cu3Oy (EBCO) thin film using the samples with antenna geometry which are nearly free from the parallel overlapping effect of the injector current and the thin film current. The injector consists of two EBCO\\/insulator\\/Au (S\\/I\\/N) gate junctions. The samples were fabricated

  10. Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

    E-print Network

    Pierre Kaufmann; Gerard Trottet; C. Guillermo Gimenez de Castro; Jean-Pierre Raulin; Sam Krucker; Albert Y. Shih; Hugo Levato

    2008-12-17

    The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.

  11. 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.

  12. Contribution of Bremsstrahlung Emission from Lyman-alpha Clouds to the Microwave Background Fluctuations

    E-print Network

    Abraham Loeb

    1995-11-16

    I calculate the contribution of Bremsstrahlung emission from Lyman-alpha absorption clouds to the brightness of the microwave sky. The calculation is based only on the assumption that the clouds below the Lyman-limit are in photoionization equilibrium with a UV background radiation, and avoids any uncertainty about the clumpiness of the gas. I predict a minimum fluctuation amplitude in the Rayleigh-Jeans regime of DeltaT/T = 10^{-5.5+-0.4}*J_21*(L/5cm)^2, which varies over characteristic angular scales of 1-100'', where L is the observed wavelength and J_21 is a weighted redshift average of the UV background intensity at the Lyman-limit in units of 10^{-21} erg cm^{-2} s^{-1} Hz^{-1} sr^{-1}. Detection of this signal can be used to map the intergalactic hydrogen distribution and to calibrate the UV background at high redshifts. Existing VLA observations constrain J_21detected are Lyman-alpha absorption systems.

  13. Influence of the microwave plasma deposition regime on the field-electron emission characteristics of nanodiamond-graphite composite films

    NASA Astrophysics Data System (ADS)

    Bushuev, N. A.; Shalaev, P. D.; Yafarov, A. R.; Yafarov, R. K.

    2015-05-01

    It is established that the field-electron emission characteristics of nanodiamond-graphite composite films deposited in nonequilibrium microwave plasma of low-pressure ethanol vapor depend on the deposition regime. The effect is explained in terms of the cluster model of deposited hydrogenated amorphous carbon (a-C:H) structure. By selecting a deposition regime so as to reduce the content of bound hydrogen in deposited carbon structures, it is possible to provide for a four- to sixfold decrease in the threshold field of field-electron emission as compared to that in a-C:H films obtained by other methods.

  14. 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.

  15. Anomalous resistivity effect on multiple ion beam emission and hard x-ray generation in a Mather type plasma focus device

    SciTech Connect

    Behbahani, R. A.; Aghamir, F. M. [Department of Physics, University of Tehran, N. Kargar Ave, Tehran 14399 (Iran, Islamic Republic of)

    2011-10-15

    Multi ion beam and hard x-ray emissions were detected in a high inductance (more than 100 nH) Mather type plasma focus (PF) device at different filling gas pressures and charging voltages. The signal analysis was performed through the current trace, as it is the fundamental signal from which all of the phenomena in a PF device can be extracted. Two different fitting processes were carried out according to Lee's computational (snow-plow) model. In the first process, only plasma dynamics and classical (Spitzer) resistances were considered as energy consumer parameters for plasma. This led to an unsuccessful fitting and did not answer the energy transfer mechanism into plasma. A second fitting process was considered through the addition of anomalous resistance, which provided the best fit. Anomalous resistance was the source of long decrease in current trace, and multi dips and multi peaks of high voltage probe. Multi-peak features were interpreted considering the second fitting process along with the mechanisms for ion beam production and hard x-ray emission. To show the important role of the anomalous resistance, the duration of the current drop was discussed.

  16. 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

  17. Microwave emission of snow in Alpine regions and the detection of surface hoar

    Microsoft Academic Search

    Giovanni Macelloni; Simonetta Paloscia; Paolo Pampaloni; Roberto Ruisi; Marco Tedesco; A. Cagnati; M. Valt

    2000-01-01

    Microwave radiometric measurements of snow packs were carried out in various test sites, to study different snow cover conditions, from dry snow at high and low density, to wet snow, and lastly, to a typical surface layer composed of big hoar crystals. It has been shown that dual-frequency (10 and 37 GHz), dual polarized microwave data appear efficient in separating

  18. Comparison of 2.8- and 21-cm microwave radiometer observations over soils with emission model calculations

    NASA Technical Reports Server (NTRS)

    Burke, W. J.; Schmugge, T.; Paris, J. F.

    1979-01-01

    An airborne experiment was conducted under NASA auspices to test the feasibility of detecting soil moisture by microwave remote sensing techniques over agricultural fields near Phoenix, Arizona at midday of April 5, 1974 and at dawn of the following day. Extensive ground data were obtained from 96 bare, sixteen hectare fields. Observations made using a scanning (2.8 cm) and a nonscanning (21 cm) radiometer were compared with the predictions of a radiative transfer emission model. It is shown that (1) the emitted intensity at both wavelengths correlates best with the near surface moisture, (2) surface roughness is found to more strongly affect the degree of polarization than the emitted intensity, (3) the slope of the intensity-moisture curves decreases in going from day to dawn, and (4) increased near surface moisture at dawn is characterized by increased polarization of emissions. The results of the experiment indicate that microwave techniques can be used to observe the history of the near surface moisture. The subsurface history must be inferred from soil physics models which use microwave results as boundary conditions.

  19. Emission, absorption and group delay of microwaves in the atmosphere in relation to water vapour content over the Indian subcontinent

    NASA Technical Reports Server (NTRS)

    Sen, A. K.; Gupta, A. K. D.; Karmakar, P. K.; Barman, S. D.; Bhattacharya, A. B.; Purkait, N.; Gupta, M. K. D.; Sehra, J. S.

    1985-01-01

    The advent of satellite communication for global coverage has apparently indicated a renewed interest in the studies of radio wave propagation through the atmosphere, in the VHF, UHF and microwave bands. The extensive measurements of atmosphere constituents, dynamics and radio meterological parameters during the Middle Atmosphere Program (MAP) have opened up further the possibilities of studying tropospheric radio wave propagation parameters, relevant to Earth/space link design. The three basic parameters of significance to radio propagation are thermal emission, absorption and group delay of the atmosphere, all of which are controlled largely by the water vapor content in the atmosphere, particular at microwave bands. As good emitters are also good absorbers, the atmospheric emission as well as the absorption attains a maximum at the frequency of 22.235 GHz, which is the peak of the water vapor line. The group delay is practically independent of frequency in the VHF, UHF and microwave bands. However, all three parameters exhibit a similar seasonal dependence originating presumably from the seasonal dependence of the water vapor content. Some of the interesting results obtained from analyses of radiosonde data over the Indian subcontinent collected by the India Meteorological Department is presented.

  20. Direct introduction of aqueous samples into a low-powered microwave-induced plasma for atomic emission spectrometry

    SciTech Connect

    Long, G.L.; Perkins, L.D.

    1987-08-01

    The direct introduction of aqueous samples into a low-power microwave plasma is achieved with the use of a highly efficient TM/sub 010/ microwave plasma. A toroidal plasma is sustained in the cavity solely by the Ar gas output of the nebulizer. Samples from a concentric glass nebulizer/Scott type spray chamber are fed directly into the cavity with no desolvation apparatus. A toroidal plasma can be sustained from the output of the nebulizer while 1 mL/min water is being aspirated at power levels of 36 W. This plasma is characterized as an atom cell by the study of emission profiles, working curves, and limits of detection. Also, ionization and vaporization interferences that occur with the use of this plasma are discussed.

  1. Determination of trace Ag, Au, Ge, Pb, Sn and Te by microwave plasma torch atomic emission spectrometry coupled with an electrothermal vaporization sample introduction system

    Microsoft Academic Search

    Qinhan Jin; Hanqi Zhang; Wenjun Yang; Qun Jin; Yuhua Shi

    1997-01-01

    An electrothermal vaporization (ETV) sample introduction device tantalum filament was combined with microwave plasma torch atomic emission spectrometry (MPT-AES) for determination of several trace elements. Some operating parameters of the system were optimized. The effects of easily ionized elements (EIEs) on the emission intensities of the tested elements were studied in detail. It was revealed that there was no interference

  2. Galactic foreground contributions to the 5-year Wilkinson Microwave Anisotropy Probe maps

    Microsoft Academic Search

    N. Macellari; E. Pierpaoli; C. Dickinson; J. E. Vaillancourt

    2011-01-01

    We compute the cross-correlation between intensity and polarization from the 5-year Wilkinson Microwave Anisotropy Probe (WMAP5) data in different sky regions with respect to template maps for synchrotron, dust and free-free emission. We derive the frequency dependence and polarization fraction for all three components in 48 different sky regions of HEALPIX (Nside= 2) pixelization. The anomalous emission associated with dust

  3. Comparison between ECMWF L-band brightness temperatures and SMOS observations using the Community Microwave Emission Modelling Platform (CMEM)

    NASA Astrophysics Data System (ADS)

    de Rosnay, Patricia; Muñoz Sabater, Joaquín; Dutra, Emanuel; Albergel, Clément; Balsamo, Gianpaolo; Boussetta, Souhail; Isaksen, Lars

    2015-04-01

    Soil moisture initialisation is crucial for Numerical Weather Prediction (NWP). New generations of satellites, such as SMOS (Soil Moisture and Ocean Salinity) and SMAP (Soil Moisture Active and Passive) provide highly suitable data from passive and active microwave sensors for soil moisture remote sensing. In order to make it possible to combine use of satellite, in situ and proxy observations to analyse soil moisture, ECMWF implemented an Extended Kalman Filter (EKF) soil moisture analysis which is used for operational NWP in the ECMWF Integrated Forecasting System (IFS). The use of passive microwave sensors in the EKF soil moisture data assimilation requires an accurate radiative transfer model. In this poster we present ECMWF developments in radiative transfer modelling conducted to use SMOS and SMAP brightness temperature observations in the ECMWF data assimilation system. The ECMWF Community Microwave Emission Modelling Platform (CMEM) is described. CMEM input global fields, including soil moisture, soil temperature, snow depth and vegetation cover, were obtained from H-TESSEL land surface model simulations forced by ERA-Interim atmospheric conditions. CMEM multi-year simulations were performed using a land surface model configuration which is similar to the current operational IFS. In CMEM, combinations of three soil dielectric models, three vegetation opacity models and four soil roughness parametrizations were used, allowing comparing 36 different configurations of the microwave emission model. Global scale forward simulations of dual polarization L-band (1.4 GHz) brightness temperature were conducted at 40 degrees incidence angle for each radiative transfer model and evaluated using the SMOS near real time brightness temperature data for 2010. Best microwave emission model performances were obtained with the Wang and Schmugge dielectric model combined with the Wigneron vegetation opacity model and the simple Wigneron soil roughness parametrization. The best CMEM configuration was used to simulate multi-angular brightness temperature at 30, 40 and 50 degrees incidence angle for 2010-2013 and evaluated against the observed SMOS brightness temperature. Results are presented at global and regional scales using RMSE, correlation and bias metrics in order to evaluate CMEM both at the monthly and annual time scales.

  4. 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.

  5. A simple flow-injection on-line clean-up system for microwave plasma-torch atomic emission spectrometry

    Microsoft Academic Search

    Liwei Zhao; Minjing Li; Xiaohang Xie; Daqian Song; Yuan Tian; Lijuan Zhang; Danhong Jin; Hanqi Zhang; Qinhan Jin

    2001-01-01

    A simple flow injection (FI) on-line clean-up system has been developed for microwave plasma-torch atomic emission spectrometry\\u000a (MPT–AES). A non-selective strongly acidic cation-exchange resin was used to achieve the goal of “on-line clean-up”. Ag and\\u000a Zr, which form halogen-complex anions in halide acid media, and Cr, Mo, and P, which exist as acid group anions or acids (neutral)\\u000a in acidic

  6. [Determination of trace metals by direct solid sample introduction and high power microwave induced nitrogen plasma atomic emission spectrometry].

    PubMed

    Zhang, Zhan-en; Wagatsuma, Kazuaki

    2003-04-01

    The possibility of using direct solid sample introduction coupled with high power microwave induced nitrogen plasma atomic emission spectrometry to determine trace metals in solid samples was investigated. The experimental results show that the solid powder sample could be readily introduced into the plasma with good stability and reproducibility by using a self-assembled solid sample introduction system. The relative standard deviation of the measurements could be controlled to be less than 1% for major components and less than 10% for minor components in the solid samples. PMID:12961896

  7. Moderate volatility analyte transport behavior with membrane desolvation reversed-phase liquid chromatography-helium microwave-induced plasma atomic emission spectroscopy

    Microsoft Academic Search

    Debashis Das; Jon W. Carnahan

    2001-01-01

    The transport behavior of moderately volatile analyte in a membrane desolvation system is examined. With the goal of atomic emission determination of liquid chromatographic analytes, a tubular polytetrafluoroethylene membrane desolvator interface was used to enhance the performance of a 120W helium microwave-induced plasma atomic emission detector. To monitor organo-chlorine compounds, Cl emission was observed at 479.5nm. Membrane desolvator conditions such

  8. Electron pitch angle scattering and the impulsive phase microwave and hard X-ray emission from solar flares

    NASA Technical Reports Server (NTRS)

    Holman, G. D.; Kundu, M. R.; Papadopoulos, K.

    1982-01-01

    Observations and theoretical considerations have led to a model for impulsive phase flare emission involving the heating and acceleration of thermal electrons in the coronal part of a magnetic loop. The bulk of the heated gas is confined between conduction fronts, but particles with velocities a few times greater than the thermal velocity can escape into the lower part of the loop. It is shown that, when the electron gyrofrequency exceeds the plasma frequency, the escaping electrons are unstable to the generation of electrostatic plasma waves which scatter the particles in pitch angle to a nearly isotropic distribution. It is also shown that this scattering can (1) enhance the microwave emission from the upper part of the loop, and (2) due to the Landau damping of both low and high phase velocity waves, can lead to one or two breaks in the impulsive-phase hard X-ray spectrum.

  9. Determination of trace levels of water in solid samples by evolved gas analysis/helium microwave plasma emission spectrometry

    SciTech Connect

    Hanamura, S.; Kirsch, B.; Winefordner, J.D.

    1985-01-01

    A method for the determination of traces of adsorbed and/or bound water in solid samples is developed. This method is made up of the combination of thermal gas evolution and helium microwave plasma emission spectrometry. The solid sample is placed in a quartz crucible which is heated electrically in a He gas flow system by a programmed power supply. Vaporized H/sub 2/O is carried into the plasma, and the atomic emission line intensities of O and H are simultaneously measured by two spectrometers. Peak areas of oxygen and hydrogen are used to measure the concentration of H/sub 2/O in the sample. A known volume of H/sub 2/O is used for calibration. Several sample analyses are performed. 9 references, 8 figures, 7 tables.

  10. Constraints on spinning dust towards Galactic targets with the Very Small Array: a tentative detection of excess microwave emission towards 3C396

    Microsoft Academic Search

    Anna Scaife; David A. Green; Richard A. Battye; Rod D. Davies; Richard J. Davis; Clive Dickinson; Thomas Franzen; Ricardo Génova-Santos; Keith Grainge; Yaser A. Hafez; Michael P. Hobson; Anthony Lasenby; Guy G. Pooley; Nutan Rajguru; Rafael Rebolo; José Alberto Rubiño-Martin; Richard D. E. Saunders; Paul F. Scott; David Titterington; Elizabeth Waldram; Robert A. Watson

    2007-01-01

    We present results from observations made at 33 GHz with the Very Small Array (VSA) telescope towards potential candidates in the Galactic plane for spinning dust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we find no evidence for anomalous emission and, in combination with Effelsberg data at 1.4 and 2.7GHz, confirm that their spectra are

  11. Constraints on spinning dust towards Galactic targets with the VSA: a tentative detection of excess microwave emission towards 3C396

    Microsoft Academic Search

    Anna Scaife; David A. Green; Richard A. Battye; Rod D. Davies; Richard J. Davis; Clive Dickinson; Thomas Franzen; Keith Grainge; Yaser A. Hafez; Michael P. Hobson; Anthony Lasenby; Guy G. Pooley; Nutan Rajguru; Rafael Rebolo; Jos ´ e; Alberto Rubi; Richard D. E. Saunders; Paul F. Scott; David Titterington; Elizabeth Waldram; Robert A. Watson

    2007-01-01

    We present results from observations made at 33 GHz with the Very Small Array\\u000a(VSA) telescope towards potential candidates in the Galactic plane for spinning\\u000adust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we\\u000afind no evidence for anomalous emission and, in combination with Effelsberg\\u000adata at 1.4 and 2.7 GHz, confirm that their spectra

  12. Characterization of near-infrared nonmetal atomic emission from an atmospheric helium microwave-induced plasma using a Fourier transform spectrophotometer

    SciTech Connect

    Hubert, J.; Van Tra, H.; Chi Tran, K.; Baudais, F.L.

    1986-08-01

    A new approach for using Fourier transform spectroscopy (FTS) for the detection of atomic emission from an atmospheric helium plasma has been developed and the results obtained are described. Among the different types of plasma source available, the atmospheric pressure microwave helium plasma appears to be an efficient excitation source for the determination of nonmetal species. The more complete microwave plasma emission spectra of Cl, Br, I, S, O, P, C, N, and He in the near-infrared region were obtained and their corrected relative emission intensities are reported. This makes qualitative identification simple, and aids in the quantitative analysis of atomic species. The accuracy of the emission wavelengths obtained with the Fourier transform spectrophotometer was excellent and the resolution provided by the FTS allowed certain adjacent emission lines to be adequate for analytical applications.

  13. 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.

  14. An helium microwave-induced plasma Fourier transform atomic emission spectrometer as a novel two-dimensional detector for gas chromatography

    SciTech Connect

    Bailey, T.D.

    1989-01-01

    The helium microwave-induced plasma (MIP) emission excitation source is a sensitive, element selective detector for gas chromatography. Fourier transform (FT) spectrometry is a technique that allows rapid simultaneous monitoring of the full spectrum of a light source. The combination of the MIP excitation course with an FT spectrometer provides a versatile simultaneous multielement gas chromatography detector. The design and construction of a helium microwave-induced plasma/Fourier transform atomic emission detector for gas chromatography is described. Examples of the operation of this instrument are given.

  15. 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

  16. Characteristics of nebulizers for microwave induced plasma atomic emission spectrometry. II. Ultrasonic nebulizers

    Microsoft Academic Search

    Krzysztof Jankowski; Dorota Karmasz; Andrzej Ramsza; Edward Reszke

    1997-01-01

    Ultrasonic nebulizers were designed and matched to low power microwave induced plasma operating conditions. The dependence of aerosol concentration on vibrational amplitude and operating temperature of the transducer as well as the carrier gas and sample flows has been studied. Optimal performance parameters of the nebulizer have been determined. Spectroscopic evaluation of analytical performance of nebulizers was carried out for

  17. First detection of nonflare microwave emissions from the coronae of single late-type dwarf stars

    Microsoft Academic Search

    D. E. Gary; J. L. Linsky

    1981-01-01

    Results are presented of a search for nonflare microwave radiation from the coronae of nearby late-type dwarf stars comparable to the sun: single stars without evidence for either a large wind or circumstellar envelope. The observing program consisted of flux measurements of six stars over a 24-h period with the VLA in the C configuration at a wavelength of 6

  18. Radar sensors based on communication low Earth orbiting satellites microwave emission

    Microsoft Academic Search

    C. Mikhail; K. Kurt; N. David

    2000-01-01

    The test results confirmed the possibility of air target detection using microwave energy generated by LEOS (low Earth orbit satellites). The authors' results also could be supported by theoretical power budget evaluation. Taking into account, that the radar cross section corresponds in the authors' case to the bistatic RCS (for traditional air targets that RCS is 10-20 dB larger than

  19. First detection of nonflare microwave emission from the coronae of single late-type dwarf stars

    Microsoft Academic Search

    D. E. Gary; J. L. Linsky

    1981-01-01

    We report on an observing program with the VLA in its C configuration to detect microwave radiation from the coronae of nearby late-type dwarf stars which are not members of close binary systems and do not have large winds. Six stars, chosen on the basis of strong apparent X-ray flux, were observed during a 24 hour period, and two stars

  20. Measuring the temperature depth profile in biological subjects through characteristic thermal microwave emissions

    Microsoft Academic Search

    V. S. Troitskii; E. A. Aranzhereev; A. V. Gustov; A. I. Oladyshkina; L. K. Siz'mina; R. V. Troitskii; V. N. Tseitlina

    1986-01-01

    We present a method of deducing the depth dependence of the temperature profile in a body by measuring the brightness temperature at a number of different microwave wavelengths. We present a theoretical basis for the method and experimental verification based on a two-layer liquid model and living subjects. We develop and verify a method for determining the temperature profile of

  1. COSMOSOMAS observations of the cosmic microwave background and Galactic foregrounds at 11 GHz: evidence for anomalous microwave emission at high Galactic latitude

    Microsoft Academic Search

    S. R. Hildebrandt; R. Rebolo; J. A. Rubiño-Martín; R. A. Watson; C. M. Gutiérrez; R. J. Hoyland; E. S. Battistelli

    2007-01-01

    We present observations with the new 11-GHz radiometer of the COSMOSOMAS experiment at the Teide Observatory (Tenerife). The sky region between 0° <= RA <= 360° and 26° <= Dec. <= 49° (ca. 6500 deg2) was observed with an angular resolution of . Two orthogonal independent channels in the receiving system measured total power signals from linear polarizations with a

  2. Theory of microwave and X-ray emission. [application to behavior of nonthermal electrons created at impulsive phase of solar flares

    NASA Technical Reports Server (NTRS)

    Takakura, T.

    1973-01-01

    The behaviour of the nonthermal electrons created at the impulsive phase of flares has been deduced from the microwave impulsive bursts and hard X-ray burst by many researchers. There is almost no doubt of the emission mechanisms that radio emissions are due to gyrosynchrotron emission and hard X-rays are collisional bremsstrahlung. However, there remain three controversial problems. One is whether the emission sources of the microwave impulsive burst and hard X-ray burst are common or not. Another is whether the injection of the nonthermal electrons into the source is impulsive or continuous. The other is the relation among the nonthermal electrons, soft X-rays, EUV flash, H-alpha kernels, and white light flares. These three problems are not independent of each other.

  3. Novel version of the microwave-coupled hollow cathode lamp for atomic emission spectrometry

    SciTech Connect

    Caroli, S.; Senofonte, O.; Violante, N.; Di Simone, L.

    1987-05-01

    A new model of the microwave-boosted hollow cathode lamp has been devised, giving considerable improvement in the coupling efficiency of the two types of discharges. For this to be achieved, a resonant cavity is interposed between the cathodic and anodic blocks of the demountable tube, causing the microwave field to interact with the plasma inside the cathode. The performance of this potentiated lamp has been tested discharging a number of elements (Al, C, Cu, Fe, Mo, and Ni). In all instances there was a significant increase in intensity of the emitted spectra, together with a noticeable diminution of background; thus signal-to-background ratios of even two orders of magnitude higher than those obtainable by conventional hollow cathode discharge lamps were achieved. An additional advantage of this combined lamp is its high stability of operation.

  4. Characteristics of nebulizers for microwave-induced plasma atomic emission spectrometry

    Microsoft Academic Search

    Krzysztof Jankowski; Dorota Karmasz; Leszek Starski; Andrzej Ramsza; Andrzej Waszkiewicz

    1997-01-01

    Frit and microcapillary array nebulizers were designed and evaluated as low-flow introduction devices of liquid samples to the low-power microwave-induced plasma. Zirconia ceramics were examined as a new frit material. A critical evaluation has been carried out of the nebulization stages, such as the formation of the primary aerosol, separation of large droplets in the spray chamber and aerosol transport

  5. 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.

  6. Simultaneous determination of bismuth and tellurium in steels by high power nitrogen microwave induced plasma atomic emission spectrometry coupled with the hydride generation technique

    Microsoft Academic Search

    Akihiro Matsumoto; Tadashi Shiozaki; Taketoshi Nakahara

    2004-01-01

    An annular-shaped, high power nitrogen microwave induced plasma (N 2-MIP) produced at atmospheric pressure by an Okamoto cavity, as a new excitation source for atomic emission spectrometry (AES), has been used for the simultaneous determination of bismuth and tellurium in steels with the hydride generation method. Under the optimized experimental conditions, the best attainable detection limits at the Bi I

  7. Diagnostics of electron beam properties from the simultaneous hard X-ray and microwave emission in the 2001 March 10 flare

    Microsoft Academic Search

    V. V. Zharkova; N. S. Meshalkina; L. K. Kashapova; A. A. Kuznetsov; A. T. Altyntsev

    2011-01-01

    Context. Microwave (MW) and hard X-ray (HXR) data are thought to be powerful means of investigating the mechanisms of particle acceleration and precipitation in solar flares, reflecting different aspects of electron interaction with ambient particles in the presence of a magnetic field. Simultaneous simulation of HXR and MW emission with the same populations of electrons is still a big challenge

  8. Matrix effects of easily ionizable elements and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry

    Microsoft Academic Search

    Zhanen Zhang; Kazuaki Wagatsuma

    2002-01-01

    Matrix effects of Na, Ca and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry were investigated with a number of atomic and ionic lines covering a wide range of energies. The plasma was sustained in an Okamoto cavity at atmospheric pressure by using nitrogen as the plasma gas as well as the nebulizer gas. Most of the atomic

  9. Behaviour of a desolvation system based on microwave radiation heating for use in inductively coupled plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

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

    1997-07-01

    The present paper describes the preliminary results obtained with a desolvation system for inductively coupled plasma atomic emission spectrometry that incorporates a heating unit based on microwave (MW) radiation. This system has been called Microwave Desolvation System (MWDS). The results have proved that MW radiation can be considered as a good choice for aerosol heating in a sample introduction system. MW radiation seems to be a more uniform way of aerosol desolvation than conductive/convective heating (i.e. lower radial temperature gradients), the degree of vaporization of the droplets is less dependent on the liquid flow rate ( Ql), and also the background noise associated with the vaporization of droplets is reduced. As regards the results obtained with MWDS, in comparison with a conventional desolvation system (CDS), they are very dependent on Ql. When heating is applied, the amount of analyte that leaves the heating step increases by 30-60% with the MWDS, irrespective of Ql, whereas for the CDS this increase is very high (up to 300%) at low Ql values (0.4 ml min -1), but almost negligible at high Ql values (2.4 ml min -1). In agreement with this, the analytical figures of merit are favourable to the CDS at low flow rates, and to the MWDS at high liquid flows. Under all the conditions studied, the amount of solvent that leaves the condensation unit are lower for MWDS than for CDS.

  10. Continuous flow and flow injection halogen generation for chloride, bromide and iodide determinations by microwave induced plasma atomic emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Camun¯a, F.; Uria, J. E. Sanchez; Medel, A. Sanz

    1993-08-01

    Continuous flow generation of molecular, volatile halogens (I 2, Br 2, Cl 2), based on chemical oxidation, is a very useful sample introduction technique in microwave induced plasma atomic emission spectrometry (MIP-AES), which provides improved transport efficiency for sample to plasma, thus enhancing the sensitivity of the determinations. Optimum conditions for halogen generation/MIP detection (chemical oxidant system, type and size of gas-liquid separator, influence of halide concentration and MIP instrumental parameters) are discussed with an aim to improving both the intensity of the emission signal, and its stabilization time for I -1, Br -1 and Cl -1 determinations. For continuous halogen generation, the influence on the MIP emission signal (and its stabilization time) of (i) the size and form of the gas-liquid separator, and (ii) the atomic weight and concentration of the halogen itself has been investigated in detail. Even for optimum conditions, iodine generation/transport to the plasma is rather slow (i.e. 4 min for signal stabilization). The use of flow injection analysis (FIA) however, allows an increase of the attainable sample throughput by up to 60 samples/h, but at the expense of a slight loss of sensitivity (20-30%) compared with continuous flow generation. The influence on the MIP signal that was observed with FIA parameters (such as the injected sample volume and flow rates of the different reagents) is discussed.

  11. Element determinations in aqueous and acetonitrile containing solutions by atomic emission spectrometry using a microwave plasma torch

    NASA Astrophysics Data System (ADS)

    Prokisch, C.; Broekaert, J. A. C.

    1998-08-01

    The analytical performance of the microwave plasma torch (MPT) as a radiation source for atomic emission spectrometry in the case of sample introduction of liquids by pneumatic nebulization using a Légère nebulizer was investigated. Aerosol loading by either water or acetonitrile (AcN) did not disturb the plasma discharge stability. The addition of Cs or AcN to aqueous solutions leads to a signal suppression in the case of Cd, Cr and Pb and a signal enhancement in the case of Li for concomitant concentrations of about 50 ?g ml -1 onwards. For aqueous solutions, the limits of detection of Cr, Cd and Pb are on the order of 0.1-1 ?g ml -1 and 5-20 ng ml -1 for Li. For Cr, dissolved as ammonium pyrrolidinedithiocarbamate (APDC) complex in an AcN/H 2O mixture (2:1), the detection limit is 0.1 ?g ml -1. When AcN is present in the aerosol, spectral background records show that the wavelength range in which atomic emission lines are free from interferences is limited as a result of strong molecular band emission spectra, especially between 350 and 430 nm.

  12. Microwave ISM Emission in the Green Bank Galactic Plane Survey: Evidence for Spinning Dust

    E-print Network

    Douglas P. Finkbeiner; Glen I. Langston; Anthony H. Minter

    2004-08-16

    We observe significant dust-correlated emission outside of H II regions in the Green Bank Galactic Plane Survey (-4 emission as majority constituents at 14 GHz, and the amplitude is at least 500 times higher than expected thermal dust emission. When combined with the Rhodes (2.326 GHz), and WMAP (23-94 GHz) data it is possible to fit dust-correlated emission at 2.3-94 GHz with only soft synchrotron, free-free, thermal dust, and an additional dust-correlated component similar to Draine & Lazarian spinning dust. The rising component generally dominates free-free and synchrotron for \

  13. Subnanogram determination of inorganic and organic mercury by helium-microwave induced plasma-atomic emission spectrometry

    SciTech Connect

    Fukushi, K. (Kobe Univ. of Mercantile Marine (Japan)); Willie, S.N.; Sturgeon, R.E. (National Research Council of Canada, Ottawa, Ontario (Canada))

    1993-02-01

    Inorganic and organic mercury were determined by helium-microwave induced plasma-atomic emission spectrometry following cold vapor generation. Whereas only inorganic mercury was reduced by stannous ion in an acidic medium, both inorganic and organic mercury (total mercury) were reduced by stannous ion in the presence of cupric ion in a basic medium. Organic mercury was determined as the difference between total and inorganic mercury. Detection limits for inorganic and organic mercury were 11 and 10 pg, respectively. The accuracy of the proposed method was verified through the determination of inorganic, total and organic mercury in two marine biological standard reference materials, DORM-1 and TORT-1. 21 refs., 1 fig., 4 tabs.

  14. Element-selective detection of gas chromatographic eluates by near infrared Échelle optical emission spectrometry on microwave-induced plasmas

    NASA Astrophysics Data System (ADS)

    Koch, J.; Okruss, M.; Franzke, J.; Florek, S. V.; Niemax, K.; Becker-Ross, H.

    2004-02-01

    Specific analytical characteristics of near-infrared Échelle microwave-induced plasma atomic emission spectrometry (NIR-Échelle-MIP-OES) with respect to the quantification of organic compounds were examined. Matrices consisting of halogenated and sulfureous hydrocarbons were gas chromatographically separated and subsequently H-, C-, F-, Cl-, Br-, I- and S-selectively analyzed. For these purposes, a compact Échelle spectrometer, designed for the high-repetitive, high-resolved and simultaneous spectra acquisition between 640 and 990 nm was used. Depending on the plasma gas applied and element considered, detection limits typically varied from 200-2200 pg/s for Ar to 70-660 pg/s for He. Furthermore, strategies to improve the over-all sensitivity are discussed. In this context, a concept, which rests on simultaneous multi-line analysis is described and experimentally proofed.

  15. Manifestation of large-scale kink oscillations of coronal loops in the low frequency modulations of solar microwave emission

    NASA Astrophysics Data System (ADS)

    Khodachenko, Maxim; Kislyakova, Kristina; Zaqarashvili, Teimuraz; Kislyakov, Albert; Panchenko, Mykhaylo; Zaitsev, Valerii; Rucker, Helmut

    Very-low-frequency fluctuations (¡ 0.01 Hz) of solar microwave radiation were analysed by means of a "sliding window" Fourier transform combined with the Wigner-Ville technique. In view of the fact that slow variations of the magnetic field in the radiation source, as well as a large-scale motion of the source, can modulate the intensity of the received radio signal, we considered large-scale kink-type oscillatory motions of coronal loops which were accompanied also by periodic magnetic stress, created near the loops footpoints during each inclination of loop, i.e. two times per the oscillation cycle. In such cases a properly located observer, besides of the modulation caused by motion of the emission diagram pattern at the main oscillation frequency, may see also modulation at a double frequency of the loop oscillation as well as much weaker higher harmonics. Therefore, the presence in the very-low-frequency spectra of the lines at the main and double frequency of the loop oscillation ("modulation pairs") may indicate about a kink-type oscillatory dynamics of the loop. Special attention in the present study has been 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. The applied data analysis technique, besides of the modulations connected with loop kink oscillations seen by TRACE, enables to detect also the modulations associated with kink oscillations of smaller (invisible for TRACE) loops. Acknowledgements: MLK and TZ acknowledge Austrian Fond zur Fürderung der wissenschaftlichen Forschung (project P21197-N16); MP and HOR acknowledge Austrian Fond zur Fürderung der wissenschaftlichen Forschung (project P20680-N16).

  16. 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.

  17. Intervalence charge transfer luminescence: interplay between anomalous and 5d - 4f emissions in Yb-doped fluorite-type crystals.

    PubMed

    Barandiarán, Zoila; Seijo, Luis

    2014-12-21

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb(2+)-Yb(3+) mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb(2+)-doped CaF2 and SrF2, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb(2+)-Yb(3+) mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f(14)-1A1g? 4f(13)((2)F7/2)5deg-1T1u absorption in the Yb(2+) part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb(3+) moiety is in the higher 4f(13)((2)F5/2) multiplet. The Yb(2+)-Yb(3+) ? Yb(3+)-Yb(2+) IVCT emission consists of an Yb(2+) 5deg ? Yb(3+) 4f7/2 charge transfer accompanied by a 4f7/2 ? 4f5/2 deexcitation within the Yb(2+) 4f(13) subshell: [(2)F5/25deg,(2)F7/2] ? [(2)F7/2,4f(14)]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF2, SrF2, BaF2, and SrCl2: the presence of IVCT luminescence in Yb-doped CaF2 and SrF2; its coexistence with regular 5d-4f emission in SrF2; its absence in BaF2 and SrCl2; the quenching of all emissions in BaF2; and the presence of additional 5d-4f emissions in SrCl2 which are absent in SrF2. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb(2+)-doped CaF2 and SrF2, the appearance of Yb(2+) 4f-5d absorption bands in the excitation spectra of the IR Yb(3+) emission in partly reduced CaF2:Yb(3+) samples, and to identify the broadband observed in the excitation spectrum of the so far called anomalous emission of SrF2:Yb(2+) as an IVCT absorption, which corresponds to an Yb(2+) 4f5/2 ? Yb(3+) 4f7/2 electron transfer. PMID:25527954

  18. Intervalence charge transfer luminescence: Interplay between anomalous and 5d - 4f emissions in Yb-doped fluorite-type crystals

    NASA Astrophysics Data System (ADS)

    Barandiarán, Zoila; Seijo, Luis

    2014-12-01

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb2+-Yb3+ mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb2+-doped CaF2 and SrF2, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb2+-Yb3+ mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f14-1A1g? 4f13(2F7/2)5deg-1T1u absorption in the Yb2+ part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb3+ moiety is in the higher 4f13(2F5/2) multiplet. The Yb2+-Yb3+ ? Yb3+-Yb2+ IVCT emission consists of an Yb2+ 5deg ? Yb3+ 4f7/2 charge transfer accompanied by a 4f7/2 ? 4f5/2 deexcitation within the Yb2+ 4f13 subshell: [2F5/25deg,2F7/2] ? [2F7/2,4f14]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF2, SrF2, BaF2, and SrCl2: the presence of IVCT luminescence in Yb-doped CaF2 and SrF2; its coexistence with regular 5d-4f emission in SrF2; its absence in BaF2 and SrCl2; the quenching of all emissions in BaF2; and the presence of additional 5d-4f emissions in SrCl2 which are absent in SrF2. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb2+-doped CaF2 and SrF2, the appearance of Yb2+ 4f-5d absorption bands in the excitation spectra of the IR Yb3+ emission in partly reduced CaF2:Yb3+ samples, and to identify the broadband observed in the excitation spectrum of the so far called anomalous emission of SrF2:Yb2+ as an IVCT absorption, which corresponds to an Yb2+ 4f5/2 ? Yb3+ 4f7/2 electron transfer.

  19. 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.

  20. Abel inversion applied to a small set of emission data from a microwave plasma.

    PubMed

    Sáinz, A; Díaz, A; Casas, D; Pineda, M; Cubillo, F; Calzada, M D

    2006-03-01

    In this work we propose a criterion to apply the Abel inversion in the case of a small set of experimental data to be used in laboratory plasmas. The Nestor-Olsen method, spline interpolation, and Fourier transform Abel inversion have been compared in order to study the influence of statistical noise and the number of sampled data. The application of this criterion permits us to obtain a radial distribution of the plasma parameters (densities and temperatures) from the spectral line profiles emitted by the discharge. The proposed criterion has been tested using the lateral intensities of several lines emitted by a microwave helium plasma column generated at atmospheric pressure. PMID:16608564

  1. 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.

  2. Characteristics of nebulizers for microwave-induced plasma atomic emission spectrometry. I. Pneumatic nebulizers

    NASA Astrophysics Data System (ADS)

    Jankowski, Krzysztof; Karmasz, Dorota; Starski, Leszek; Ramsza, Andrzej; Waszkiewicz, Andrzej

    1997-10-01

    Frit and microcapillary array nebulizers were designed and evaluated as low-flow introduction devices of liquid samples to the low-power microwave-induced plasma. Zirconia ceramics were examined as a new frit material. A critical evaluation has been carried out of the nebulization stages, such as the formation of the primary aerosol, separation of large droplets in the spray chamber and aerosol transport to the plasma torch; changes in the design of the nebulizers studied were introduced on this basis. The characteristics of nebulizers were supplemented by spectroscopic measurements of the measured signal stability, detection limits for selected elements and wash-out times.

  3. Soft X-ray, microwave, and hard X-ray emission from a solar flare - Implications for electron heating and acceleration in current channels

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

    1989-01-01

    The soft X-ray, microwave, and hard X-ray emissions from the solar flare of May 14, 1980 are studied. The flare consists of a gradual component in soft X-rays and microwaves and a superposed impulsive burst accompanied by hard X-ray emission. The impulsive phase of the flare appears in the soft X-ray emission as a temperature spike and as an increased rate of energy dissipation into the plasma. A new, spatially and spectrally distinct, microwave component appears during the impulsive burst. The data are interpreted in terms of Joule heating and the electric field acceleration of electrons in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft X-ray emitting plasma can be heated by a single current sheet only if the resistivity in the sheet is well above the classical, collisional resistivity. Conditions are also given for the hard X-ray emission to be from nonthermal electrons with classical resistivity.

  4. 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.

  5. Frequency and Angular Variations of Land Surface Microwave Emissivities: Can we Estimate SSM/T and AMSU Emissivities from SSM/I Emissivities?

    NASA Technical Reports Server (NTRS)

    Prigent, Catherine; Wigneron, Jean-Pierre; Rossow, William B.; Pardo-Carrion, Juan R.

    1999-01-01

    To retrieve temperature and humidity profiles from SSM/T and AMSU, it is important to quantify the contribution of the Earth surface emission. So far, no global estimates of the land surface emissivities are available at SSM/T and AMSU frequencies and scanning conditions. The land surface emissivities have been previously calculated for the globe from the SSM/I conical scanner between 19 and 85 GHz. To analyze the feasibility of deriving SSM/T and AMSU land surface emissivities from SSM/I emissivities, the spectral and angular variations of the emissivities are studied, with the help of ground-based measurements, models and satellite estimates. Up to 100 GHz, for snow and ice free areas, the SSM/T and AMSU emissivities can be derived with useful accuracy from the SSM/I emissivities- The emissivities can be linearly interpolated in frequency. Based on ground-based emissivity measurements of various surface types, a simple model is proposed to estimate SSM/T and AMSU emissivities for all zenith angles knowing only the emissivities for the vertical and horizontal polarizations at 53 deg zenith angle. The method is tested on the SSM/T-2 91.655 GHz channels. The mean difference between the SSM/T-2 and SSM/I-derived emissivities is less than or equal to 0.01 for all zenith angles with an r.m.s. difference of approx. = 0.02. Above 100 GHz, preliminary results are presented at 150 GHz, based on SSM/T-2 observations and are compared with the very few estimations available in the literature.

  6. Effect of adding oxygen gas to a high power nitrogen microwave-induced plasma for atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Ohata, Masaki; Ota, Hironobu; Fushimi, Motohiro; Furuta, Naoki

    2000-10-01

    In order to investigate the effect of adding oxygen gas (O 2) to a high power nitrogen microwave-induced plasma (N 2-MIP: 2.45 GHz, surface wave mode) for atomic emission spectrometry, the signal intensities for atom and ion lines of Ca, V, Ti, Mg, and Cd were observed by adding O 2 gas into N 2 outer gas in a range from 0 to 20%. From the observation of the background spectrum in a wavelength range of 200-400 nm, it was found that NO band spectra were enhanced largely with an increase in the addition of O 2 gas. The excitation temperatures ( Tex) observed decreased from 5500 to 4800 K with an increase in the percentage of adding O 2 gas from 0 to 20%. The relatively large signal enhancement was observed for all atom lines of Ca, V, Ti, Mg, and Cd when O 2 gas was added to N 2 outer gas. The emission signals for some of ion lines of Ca, V, Ti, and Mg also showed a signal enhancement when a small amount of O 2 gas was added. It was considered that the reason for the enhancement phenomena of the ion lines of these elements was attributed to the mechanism of the charge transfer reaction.

  7. Anomalous magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2013-09-01

    Anomalous symmetries induce currents which can be parallel rather than orthogonal to the hypermagnetic field. Building on the analogy of charged liquids at high magnetic Reynolds numbers, the persistence of anomalous currents is scrutinized for parametrically large conductivities when the plasma approximation is accurate. Different examples in globally neutral systems suggest that the magnetic configurations minimizing the energy density with the constraint that the helicity be conserved coincide, in the perfectly conducting limit, with the ones obtainable in ideal magnetohydrodynamics where the anomalous currents are neglected. It is argued that this is the rationale for the ability to extend to anomalous magnetohydrodynamics the hydromagnetic solutions characterized by finite gyrotropy. The generally covariant aspects of the problem are addressed with particular attention to conformally flat geometries which are potentially relevant for the description of the electroweak plasma prior to the phase transition.

  8. 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.

  9. 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...

  10. Constraints on spinning dust towards Galactic targets with the VSA: a tentative detection of excess microwave emission towards 3C396

    E-print Network

    Anna Scaife; David A. Green; Richard A. Battye; Rod D. Davies; Richard J. Davis; Clive Dickinson; Thomas Franzen; Ricardo Genova-Santos; Keith Grainge; Yaser A. Hafez; Michael P. Hobson; Anthony Lasenby; Guy G. Pooley; Nutan Rajguru; Rafael Rebolo; Jose Alberto Rubino-Martin; Richard D. E. Saunders; Paul F. Scott; David Titterington; Elizabeth Waldram; Robert A. Watson

    2007-02-19

    We present results from observations made at 33 GHz with the Very Small Array (VSA) telescope towards potential candidates in the Galactic plane for spinning dust emission. In the cases of the diffuse HII regions LPH96 and NRAO591 we find no evidence for anomalous emission and, in combination with Effelsberg data at 1.4 and 2.7 GHz, confirm that their spectra are consistent with optically thin free--free emission. In the case of the infra-red bright SNR 3C396 we find emission inconsistent with a purely non-thermal spectrum and discuss the possibility of this excess arising from either a spinning dust component or a shallow spectrum PWN, although we conclude that the second case is unlikely given the strong constraints available from lower frequency radio images.

  11. Microwave plasma-atomic emission spectroscopy as a tool for the determination of copper, iron, manganese and zinc in animal feed and fertilizer.

    PubMed

    Li, Wei; Simmons, Patrick; Shrader, Doug; Herrman, Timothy J; Dai, Susie Y

    2013-08-15

    Quantitative analysis of elements in agricultural products like animal feed and fertilizers by a new instrument using microwave plasma-atomic emission spectroscopy (MP-AES) technology was demonstrated in this work. Hot plate and microwave digestion were used to digest the sample matrices and the consequent digests were subject to atomic absorption spectroscopy (AA), inductive coupled plasma optical emission spectroscopy (ICP-OES) and MP-AES analysis. The detection limit, accuracy and dynamic range for each instrument, were compared and matrix effects were evaluated with respect to the fertilizer and feed materials. The new MP-AES platform can offer comparable or better performance compared to AA and/or ICP-OES with respect to routine analysis for a regulatory program. PMID:23708535

  12. Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission

    NASA Astrophysics Data System (ADS)

    Dunn, David E.; Molnar, Lawrence A.; Niehof, Jon T.; de Pater, Imke; Lissauer, Jack J.

    2004-09-01

    We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of ?3.6 cm. The moderate ring opening angle ( B?15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.

  13. Evaluating the First-Order Tau-Omega Model of Terrestrial Microwave Emission

    Microsoft Academic Search

    Brian K. Hornbuckle; Tracy L. Rowlandson

    2008-01-01

    We have formulated a first-order tau-omega model. Compared to the commonly-used zero-order model, this model has four new terms that each represent a scattering mechanism. We found that the first mechanism, the scattering of emission from the vegetation into the upwelling beam, is the most significant. We also found that this term does not affect the overall soil moisture sensitivity

  14. Long-lived explosive-emission cathode for high-power microwave radiation generators

    Microsoft Academic Search

    A. V. Gunin; V. F. Landl’; S. D. Korovin; G. A. Mesyats; V. V. Rostov

    1999-01-01

    The operation of cold explosive-emission cathodes having a current density of ?104 A\\/cm2, fabricated using various materials, was investigated under a large number of switching cycles. The cathode voltage was ?500\\u000a kV, the maximum current ?5 kA, and the pulse duration ?20 ns. It is shown that when the number of switchings is small (?103 pulses), cathodes having similar geometry

  15. Compact sources of suprathermal microwave emission detected in quiescent active regions during lunar occulatations

    Microsoft Academic Search

    E. Correia; P. Kaufmann; F. Strauss

    1992-01-01

    Solar quiescent active regions are known to exhibit radio emission from discrete structures. The knowledge of their dimensions and brightness temperatures is essential for understanding the physics of quiescent confined plasma regions. Solar eclipses of 10 August 1980 and 28 January 1990, observed with high sensitivity (0.01 s.f.u.) and high time resolution (30 ms) at 22 GHz, allowed the unprecedented

  16. Detection of microwave emission from both components of the red dwarf binary EQ Pegasi

    Microsoft Academic Search

    K. Topka; K. A. Marsh

    1982-01-01

    The detection at 4.9 GHz of the late main sequence binary EQ Pegasi (dM3.5e + dM4.5e) with the VLA is reported. Both components were detected, as flux levels of 0.69 mJy and 0.4 mJy, respectively. Thermal gyroresonance emission from the quiescent coronae of these stars appears to explain observations of the authors, as it does those of Gary and Linsky

  17. Determination of major and trace elements in biological materials by microwave induced plasma optical emission spectrometry (MIP-OES) following tetramethylammonium hydroxide (TMAH) solubilization

    Microsoft Academic Search

    Henryk Matusiewicz; Bartosz Golik

    2004-01-01

    A simple, alternative method to acid digestion is presented for the preparation of biological materials for major and trace elements by microwave induced plasma optical emission spectrometry (MIP-OES). Standard reference materials were solubilized using a methanolic solution of tetramethylammonium hydroxide (TMAH) by the application of ultrasonic agitation. Following dilution with water suspensions were pumped to a V-groove Babington-type nebulizer then

  18. Optimization of electrochemical hydride generation in a miniaturized electrolytic flow cell coupled to microwave-induced plasma atomic emission spectrometry for the determination of selenium

    Microsoft Academic Search

    S. Schermer; L. Jurica; J. Paumard; E. Beinrohr; F.-M. Matysik; J. Broekaert

    2001-01-01

    The optimization of a continuous flow system for electrochemical hydride generation coupled to microwave-induced plasma atomic emission spectrometry (MIP-AES) for the determination of Se is presented. A small electrolytic cell with a porous glassy carbon working electrode was used for hydride generation. When using an Ar MIP operated in a TE101 cavity a detection limit of 0.6 ng mL-1 (3C)

  19. Characterization of a low-pressure chlorine plasma column sustained by propagating surface waves using phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy

    Microsoft Academic Search

    S. Mattei; O. Boudreault; R. Khare; L. Stafford; V. M. Donnelly

    2011-01-01

    Phase-sensitive microwave interferometry and trace-rare-gas optical emission spectroscopy were used to measure the line-integrated electron density, ne, and electron temperature, Te, in a high-density chlorine plasma sustained in a quartz discharge tube (inner diameter = 6 mm) by an electromagnetic surface wave at 2.45 GHz. For pressures in the 0.1-1 Torr range, ne decreased nearly linearly along the tube's z-axis

  20. Multielement determination of heavy metals in water samples by continuous powder introduction microwave-induced plasma atomic emission spectrometry after preconcentration on activated carbon

    Microsoft Academic Search

    Krzysztof Jankowski; Jun Yao; Krzysztof Kasiura; Adrianna Jackowska; Anna Sieradzka

    2005-01-01

    A novel continuous powder introduction microwave-induced plasma atomic emission spectrometry method (CPI-MIP-AES) has been developed for trace determination of metals in ground and tap water samples after preconcentration on activated carbon. The experimental setup consisted of integrated rectangular cavity TE101 and vertically positioned plasma torch. The technical arrangement of the sample introduction system has been designed based on the fluidized

  1. Volatile organo-selenium speciation in biological matter by solid phase microextraction–moderate temperature multicapillary gas chromatography with microwave induced plasma atomic emission spectrometry detection

    Microsoft Academic Search

    C. Dietz; J. Sanz Landaluze; P. Ximénez-Embún; C. Cámara

    2004-01-01

    Microwave induced plasma atomic emission spectrometry (MIP-AES) in combination with multicapillary (MC) gas chromatography could be proven to be useful for element specific detection of volatile species. Solid phase microextraction (SPME) was used for preconcentration and sample-matrix separation. The fiber desorption unit as well as the heating control for the MC column were in-house developed and multicapillary column was operated

  2. Coupling on-line preconcentration by ion-exchange with microwave plasma torch-atomic emission spectrometry for the determination of cobalt and nickel

    Microsoft Academic Search

    Xiangfei Kong; Qiong Jia; Weihong Zhou

    2007-01-01

    In the present work, a simple and sensitive preconcentration-microwave plasma torch-atomic emission spectrometric procedure was carried out for the determination of cobalt and nickel. The method was based upon a flow-injection system with on-line preconcentration of the metal ions on a minicolumn of a strong acid cation-exchange resin. The operation parameters including sample acidity, flow rate, loading time, and eluent

  3. Determination of precious metals in geological samples by continuous powder introduction microwave induced plasma atomic emission spectrometry after preconcentration on activated carbon

    Microsoft Academic Search

    K. Jankowski; A. Jackowska; P. ?ukasiak

    2005-01-01

    A novel method was developed for analysing geological materials for Au, Ag, Pd and Pt by continuous powder introduction microwave induced plasma atomic emission spectrometry (CPI–MIP–AES). The preconcentration of the trace metals on activated carbon (AC) was performed before conducting MIP–AES measurements in order to obtain accurate and precise analytical results. The method proposed is based on the selective sorption

  4. Continuous-flow determination of aqueous sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry with gas-phase sample introduction

    Microsoft Academic Search

    Taketoshi Nakahara; Toshio Mori; Satoru Morimoto; Hiroshi Ishikawa

    1995-01-01

    A simple continuous-flow generation of volatile hydrogen sulfide and sulfur dioxide by acidification of aqueous sulfide and sulfite ions, respectively, is described for the determination of low concentrations of sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (MIP-AES) in the normal ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum. For measuring spectral lines in the VUV region,

  5. Quantitative analysis in gas chromatography\\/low power atmospheric-pressure helium microwave-induced plasma atomic emission interferometry and ion cyclotron resonance mass spectroscopy

    Microsoft Academic Search

    Loo

    1990-01-01

    The development of experimental and data analysis techniques for quantitative analysis in gas chromatography\\/low power atmospheric pressure helium microwave-induced plasma atomic emission interferometry (GC\\/HeMIPAEI) and ion cyclotron resonance mass spectroscopy (ICR\\/MS) is presented. A discussion of interferometric data analysis by discrete and fast Fourier transform (DFT and FFT, respectively) is given. Additionally, the use of two techniques (the maximum entropy

  6. Solution nebulization into a low-power argon microwave-induced plasma for atomic emission spectrometry: study of synthetic ocean water

    Microsoft Academic Search

    Kin C. Ng; Wei Lung. Shen

    1986-01-01

    A MAK nebulizer is used to introduce liquid aerosols containing Cr, Mn, In, V, Pb, Sr, or Zr into a low-power (105-115 W), low argon flow (537 mL\\/min) microwave-induced plasma for atomic emission spectrometry. Detection limits (3sigma) in 3% nitric acid water samples are at the parts-per-billion level (62, 18, 18, 91, 139, 13, and 3945, respectively). These values compared

  7. Direct determination of trace elements in niobium, tantalum and their oxides by inductively coupled plasma atomic emission spectrometry after microwave dissolution

    Microsoft Academic Search

    O. N. Grebneva; I. V. Kubrakova; T. F. Kudinova; N. M. Kuz'min

    1997-01-01

    Analytical schemes for the determination of trace elements in high-purity niobium, tantalum and their oxides are proposed. The schemes are based on microwave dissolution of the metals and oxides followed by inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of impurities in the solutions. The possibilities of interelement and off-peak background corrections in ICP-AES analysis are discussed. The accuracy of

  8. 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.

  9. Enhancement of secondary electron emission by annealing and microwave hydrogen plasma treatment of ion-beam-damaged diamond films

    NASA Astrophysics Data System (ADS)

    Laikhtman, A.; Hoffman, A.

    2002-02-01

    In this work we investigate the influence of annealing and microwave (MW) hydrogen plasma exposure of ion-beam-irradiated diamond film surfaces. In particular, we are interested in the recovery of secondary electron emission (SEE) and negative electron affinity (NEA) by removal of the damaged layer. To this aim, we correlate the SEE of variously treated Xe+ ion-damaged diamond films with their bonding structure in the near-surface region, as identified by near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and x-ray photoelectron spectroscopy. The 30 keV Xe+ ion bombardment of hydrogenated polycrystalline diamond films to a dose of 2×1015 cm-2 results in the transformation of the near-surface region of a diamond film to sp2-bonded amorphous carbon, increased oxygen adsorption, shift of the electron affinity from negative to positive, and strong degradation of its electron emission properties, although it does not induce a pronounced depletion of hydrogen. Exposure of the ion-bombarded films to MW hydrogen plasma treatment for 30 min produces NEA diamond surfaces, but only partially regenerates SEE properties, retains some imperfection in the near-surface atomic layers, as determined by NEXAFS, and the concentration of oxygen remains relatively high. Subsequent annealing to 610 °C produces oxygen-free diamond films and somewhat increases their SEE. Annealing to 1000 °C results in desorption of the surface hydrogen, formation of positive electron affinity surfaces, and drastically degrades their electron emission properties. Prolonged (up to three hours) MW hydrogen plasma treatment of as-implanted diamond films gradually improves their crystal quality and results in a further increase of SEE intensity. The SEE intensity after three hours MW hydrogen plasma exposure of the ion-beam-irradiated films was found to be ˜50% above the value obtained for the as-deposited diamond films. This treatment does not, however, substantially reduce the concentration of oxygen in the previously damaged diamond, indicating its bulk diffusion during or after ion bombardment. Our results show that removal of damage from a highly disordered diamond surface and recovery of its electron emission properties are possible by MW hydrogen plasma. However, it is a slow process. This is most likely due to the very low etching rate of the low-level damage at the end of the ion beam range.

  10. 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

  11. Electric field-assisted metal insulator transition in vanadium dioxide (VO2) thin films: optical switching behavior and anomalous far-infrared emissivity variation

    NASA Astrophysics Data System (ADS)

    Crunteanu, Aurelian; Fabert, Marc; Cornette, Julie; Colas, Maggy; Orlianges, Jean-Christophe; Bessaudou, Annie; Cosset, Françoise

    2014-03-01

    We present the vanadium dioxide (VO2) thin films deposition using e-beam evaporation of a vanadium target under oxygen atmosphere on different substrates (sapphire, Si, SiO2/Si…) and we focus on their electrical and optical properties variations as the material undergoes a metal-insulator transition under thermal and electrical stimuli. The phase transition induces extremely abrupt changes in the electronic and optical properties of the material: the electrical resistivity increases up to 5 orders of magnitude while the optical properties (transmission, reflection, refractive index) are drastically modified. We present the integration of these films in simple planar optical devices and we demonstrate electrical-activated optical modulators for visible-infrared signals with high discrimination between the two states. We will highlight a peculiar behavior of the VO2 material in the infrared and far infrared regions (2- 20 ?m), namely its anomalous emissivity change under thermal- end electrical activation (negative differential emittance phenomenon) with potential applications in active coatings for thermal regulation, optical limiting or camouflage coatings.

  12. Lower hybrid resonance acceleration of electrons and ions in solar flares and the associated microwave emission

    NASA Technical Reports Server (NTRS)

    Mcclements, K. G.; Bingham, R.; Su, J. J.; Dawson, J. M.; Spicer, D. S.

    1993-01-01

    The particle acceleration processes here studied are driven by the relaxation of unstable ion ring distributions; these produce strong wave activity at the lower hybrid resonance frequency which collapses, and forms energetic electron and ion tails. The results obtained are applied to the problem posed by the production of energetic particles by solar flares. The numerical simulation results thus obtained by a 2 1/2-dimensional particle-in-cell code show a simultaneous acceleration of electrons to 10-500 keV energies, and of ions to as much as the 1 MeV range; the energy of the latter is still insufficient to account for gamma-ray emission in the 4-6 MeV range, but furnish a seed population for further acceleration.

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

    Microsoft Academic Search

    Alejandro N. Flores; Valeriy Y. Ivanov; Dara Entekhabi; Rafael L. Bras

    2009-01-01

    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 microwave brightness temperatures in a way that produces bias at coarser scales (kilometers). The physics underlying soil moisture remote sensing suggests that the effects of topography on

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

    NASA Astrophysics Data System (ADS)

    Papoular, R.

    2015-07-01

    Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from ˜20 to more than 104 ?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 ?m 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 allows the extinction cross-section per H atom, and its maximum wavelength, to be determined as a function of molecular size and dimensionality. Chemical modelling of more than 15 large molecules illustrates these results. It is found that the maximum phonon wavelength of a 2D structure increases roughly as the square of its larger dimension. Spectral energy distributions were computed as far as 4000 ?m, for molecules up to 50 Å in length.

  15. 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.

  16. 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

  17. [Determination of nine hazardous elements in textiles by inductively coupled plasma optical emission spectrometer after microwave-assisted dilute nitric acid extraction].

    PubMed

    Chen, Fei; Xu, Dian-dou; Tang, Xiao-ping; Cao, Jing; Liu, Ya-ting; Deng, Jian

    2012-01-01

    Textiles are easily contaminated by heavy metals in the course of processing. In order to monitor the quality of textiles, a new method was developed for simultaneous determination of arsenic, antimony, lead, cadmium, chromium, cobalt, copper, nickel and mercury in textiles by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted dilute nitric acid extraction. After optimizing extraction conditions, we ultimately selected 5% nitric acid as extractant and 5 min as extraction time with the extraction temperature of 120 degrees C and instrument power of 400W in the microwave-assisted extraction procedure. Nine hazardous elements were detected sequentially by ICP-OES. The results showed that the detection limits were 0.3-15 microg x L(-1) and the recoveries 73.6%-105% with the RSDs (n = 3) of 0.1%-3%. The proposed method was successfully used to determine nine elements in cotton, wool, terylene and acrylic. PMID:22497167

  18. Plasma relativistic microwave electronics

    Microsoft Academic Search

    M. V. Kuzelev; O. T. Loza; A. A. Rukhadze; P. S. Strelkov; A. G. Shkvarunets

    2001-01-01

    The principles of plasma relativistic microwave electronics based on the stimulated Cherenkov emission of electromagnetic\\u000a waves during the interaction of a relativistic electron beam with a plasma are formulated. A theory of relativistic Cherenkov\\u000a plasma microwave oscillators and amplifiers is developed, and model experimental devices are elaborated and investigated.\\u000a The emission mechanisms are studied theoretically. The efficiencies and frequency spectra

  19. 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 ...

  20. 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.

  1. Direct coupling of continuous hydride generation with microwave plasma torch atomic emission spectrometry for the determination of arsenic, antimony and tin

    NASA Astrophysics Data System (ADS)

    Pereiro, Rosaria; Wu, Min; Broekaert, Jose A. C.; Hieftje, Gary M.

    1994-01-01

    The effect of adding hydrogen to the carrier-gas flow of a helium microwave plasma torch (MPT) discharge is evaluated in terms of plasma stability, continuum background and helium emission intensities. Also, the noise characteristics of the emission signal from the helium MPT source has been studied with special emphasis on the effect of added hydrogen. Because the MPT source can tolerate ratios of H 2/He carrier of up to 30% hydrogen, a continuous hydride-generation apparatus was coupled directly to the He MPT. The effect of the carrier and support-gas flow rates, and microwave forward power were evaluated for the determination of arsenic. The system was applied to the determination of arsenic, antimony and tin by atomic emission spectrometry. Detection limits (3?) of 3.2, 5.9 and 2.5 ng ml -1 were obtained for As, Sb and Sn, respectively, when a plasma power of 200 W was used. Linear dynamic ranges were over 3 orders of magnitude for the three elements. The argon MPT source accepts the introduction of hydrogen up to carrier-gas ratios of 20%, but yields a detection limit for As of only 65 ng ml -1.

  2. Adirectly Coupled Microwave-Induced Plasma Atomic Emission Liquid Chromatograpy Detector for Nonmetals: Preliminary Characterization with Halides and Oxohalogen Salts

    Microsoft Academic Search

    Kevin G. Michlewicz; Jon W. Carnahan

    1987-01-01

    A liquid chromatography system is directly coupled to a moderate power helium microwave induced plasma for the selective determination of no metals in aqueous solutions. The detector is a large volume helium microwave-induced plasma operated at 500 watts with a helium support gas flow of 21L\\/min. A sample set of halides and oxohalgen salts are separated by ion exchange chromatography

  3. A Search for Prompt Microwave Emission from Gamma-Ray Bursts Using Archival COBE and WMAP Datasets

    Microsoft Academic Search

    M. Mbonye; J. G. Stacy; P. D. Jackson; C. Winkler

    2004-01-01

    We report on an extension of earlier work to search the archival database of the Differential Microwave Radiometers (DMR) aboard the COBE satellite, and the more recent public time-ordered datasets acquired with the Wilkinson Microwave Anisotropy Probe (WMAP), for transient signals associated with cosmic gamma-ray bursts (GRBs). Over the course of its 4-year mission the COBE\\/DMR serendipitously observed a number

  4. Wideband detection of amplitude- and frequency-modulated microwave emission by YBa2Cu3O(x) ceramic

    Microsoft Academic Search

    V. N. Bogomolov; Iu. A. Kumzerov; S. G. Romanov; A. V. Fokin

    1989-01-01

    The behavior of YBa2Cu3O(x) superconducting ceramic in the microwave detection mode is investigated experimentally for the cases of both amplitude and frequency modulation. The response of the ceramic to amplitude-modulated microwave radiation is found to be generally similar to that of single Josephson junctions in the wideband detection mode but the intensity of the response is approximately a factor of

  5. Analyte volatilization procedure for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry 1 This paper is published in honour of Professor C.L. Chakrabarti. 1

    Microsoft Academic Search

    Taketoshi Nakahara; Takahiro Nishida

    1998-01-01

    A simple method is described for the generation of a continuous flow of volatile chlorine by the oxidation of aqueous chloride for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (He MIP-AES). The chlorine atom emission line at 438.976nm and ion emission lines at 479.454 and 481.006nm were selected as the analytical lines

  6. Matrix effects of easily ionizable elements and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Zhanen; Wagatsuma, Kazuaki

    2002-08-01

    Matrix effects of Na, Ca and nitric acid in high-power microwave-induced nitrogen plasma atomic emission spectrometry were investigated with a number of atomic and ionic lines covering a wide range of energies. The plasma was sustained in an Okamoto cavity at atmospheric pressure by using nitrogen as the plasma gas as well as the nebulizer gas. Most of the atomic lines tested exhibited enhancement effects and all of the ionic lines gave suppression effects in the presence of Na and Ca. The effects decreased with increasing microwave power. There was good correlation between matrix effects, the excitation energy and energy sum of the spectral lines. The lower the excitation energy for atomic lines and the higher the energy sum for ionic lines, the stronger the matrix effects. Unlike Na and Ca, nitric acid showed suppression effect for all of the spectral lines and the effect was independent of the energy of the spectral lines and the microwave power. The effect of matrix on the excitation temperature and the electron number density was measured and the mechanism of matrix effect was discussed.

  7. 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.

  8. Investigations on the on-line determination of metals in air flows by capacitively coupled microwave plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Seelig, M.; Broekaert, J. A. C.

    2001-09-01

    Plasma optical emission spectrometry with a capacitively coupled microwave plasma (CMP) operated with air has been investigated with respect to its possibilities for real-time environmental monitoring of combustion processes. The unique feature is the possibility to operate the CMP with air as working gas, as is usually the case in exhaust gases of combustion processes. The CMP also is shown to be stable in the presence of large amounts of water and CO 2, which makes this source ideally suitable for this purpose. The detection limits obtained for the environmentally relevant elements Cd, Co, Cr, Fe, Mg, Ni and Pb show the possibility to monitor directly heavy metals in air in an on-line mode and down to the 2-160-?g m -3 level. These detection limits are generally lower than the threshold limit values of the 'Federal Law for Immission Protection' in Germany in the gaseous effluents of industrial plants. In order to investigate the influence of the water loading (32-222 g m -3) on the detection limits a comparison of results obtained with three different nebulizers (Légère nebulizer, hydraulic high-pressure nebulizer and ultrasonic nebulizer) was made, with which aerosols with different water loading are entered into the plasma. For the hydraulic high-pressure nebulizer and the ultrasonic nebulizer no desolvation unit was found to be necessary. It was shown that especially for elements with lines having high excitation energy (Cd) or for which ion lines are used (Mg II) the increase in water loading deteriorates the detection limits. The rotational temperatures ( Trot) and excitation temperatures ( Texe) in the case of different amounts of water are of the order of 3700-4900 K and 4700-7100 K, respectively. The temperatures show that changes in the geometry and temperature distribution in the case of Trot but also the values of Texe themselves are responsible for this increase in detection limits. Furthermore, different amounts of CO 2 mixed to the working gas (3-22%) while the total gas flow rate was kept constant at 1.2 l min -1 were also shown to increase the detection limits.

  9. Vacuum ultraviolet emission spectrum measurement of a microwave-discharge hydrogen-flow lamp in several configurations: Application to photodesorption of CO ice

    SciTech Connect

    Chen, Y.-J.; Wu, C.-Y. R. [Space Sciences Center and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-1341 (United States); Chuang, K.-J.; Chu, C.-C.; Yih, T.-S. [Department of Physics, National Central University, Jhongli City, Taoyuan County 32054, Taiwan (China); Muñoz Caro, G. M. [Centro de Astrobiología, INTA-CSIC, Torrejón de Ardoz, E-28850 Madrid (Spain); Nuevo, M. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Ip, W.-H., E-mail: yujung@usc.edu [Graduate Institute of Astronomy, National Central University, Jhongli City, Taoyuan County 32049, Taiwan (China)

    2014-01-20

    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 H{sub 2} 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 H{sub 2} inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H{sub 2} versus H{sub 2} seeded in He), and the optical properties of the window used (MgF{sub 2} versus CaF{sub 2}). 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 H{sub 2} molecular emission ranges.

  10. Determination of sub-nanogram-per-liter levels of mercury in lake water with atmospheric pressure helium microwave induced plasma emission spectrometry

    SciTech Connect

    Nojiri, Y.; Otsuki, A.; Fuwa, K.

    1986-03-01

    A highly sensitive method for the analysis of Hg was developed utilizing atmospheric pressure He microwave induced plasma (He-MIP) emission spectrometry. Mercury vapor was generated from water samples by reduction and purging and was collected with a gold amalgamation trap. The Hg vapor, removed by heating the trap, was introduced into the He-MIP. The atomic emission line of 253.7 nm was used for the determination of Hg. The detection limit, defined as 3 times the standard deviation of the blank operations, was 0.5 pg in 50 mL of water sample, corresponding to 0.01 ng/L. The method was applied to the determination of ultratrace levels of Hg in lake water samples. The inorganic Hg concentration in subsurface water from unpolluted Lake Mashu was found to be 0.3 ng/L. 29 references, 3 figures, 1 table.

  11. Effect of a self-induced electric field on the electron beam kinetics and resulting hard X-ray and microwave emissions in flares

    NASA Astrophysics Data System (ADS)

    Zharkova, V. V.; Meshalkina, N. S.; Kashapova, L. K.; Altyntsev, A. T.; Kuznetsov, A. A.

    2011-12-01

    The kinetics of beam electron precipitation from the top of a loop into the solar atmosphere with density gradients and an increasing magnetic field have been generally described. The Fokker-Planck equations are solved with regard to Coulomb collisions and the effect of the electric field induced by this beam. The photon spectra and polarization degree in hard X-ray (10-300 keV) and microwave (1-80 GHz) emissions are simulated under different assumptions regarding the beam electron distribution function. The simulation results are compared with the flare observations on March 10, 2001, and July 23, 2002, visible at different position angles. It has been indicated that the coincidence of the theoretical photon spectra with simultaneous observations of the hard X-ray and microwave emissions of these flares is the best for models that not only take into account collisions, but also the electric field induced by electron fluxes propagating in flare loops with very weakly or moderately converging magnetic fields.

  12. 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.

  13. 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.

  14. 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.

  15. Models of Polarized Emission from Interstellar Dust Grains

    NASA Astrophysics Data System (ADS)

    Draine, Bruce

    2015-04-01

    Nonspherical aligned dust grains produce strong linearly-polarized thermal emission at submm and microwave frequencies, with polarized fractions exceeding 20% in some parts of the high-latitude sky. Observations of emission, absorption, and scattering by dust, together with our knowledge of the abundances of elements out of which dust grains can be formed, impose many constraints on dust modelers. The dust is in large part composed of amorphous silicates, but with a substantial component of carbonaceous materials, including nanoparticles of polycyclic aromatic hydrocarbons. The smallest particles radiate thermally in the mid-IR following single-photon heating, and also produce rotational emission at microwave frequencies. This rotational emission may account for the so-called Anomalous Microwave Emission. Iron contributes about 25% of the total mass of interstellar dust, but what form the Fe is in is largely unknown; much of the Fe could be in ferromagnetic or ferrimagnetic materials that could emit magnetic dipole radiation at microwave frequencies. I will review the observational constraints on dust models, the current state of our physical models, and prospects for further progress.

  16. 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

  17. 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.

  18. Long wavelength (>1.55 {mu}m) room temperature emission and anomalous structural properties of InAs/GaAs quantum dots obtained by conversion of In nanocrystals

    SciTech Connect

    Urbanczyk, A.; Keizer, J. G.; Koenraad, P. M. [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)] [COBRA Research Institute on Communication Technology, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Noetzel, R. [Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)] [Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), ETSI Telecommunication, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2013-02-18

    We demonstrate that molecular beam epitaxy-grown InAs quantum dots (QDs) on (100) GaAs obtained by conversion of In nanocrystals enable long wavelength emission in the InAs/GaAs material system. At room temperature they exhibit a broad photoluminescence band that extends well beyond 1.55 {mu}m. We correlate this finding with cross-sectional scanning tunneling microscopy measurements. They reveal that the QDs are composed of pure InAs which is in agreement with their long-wavelength emission. Additionally, the measurements reveal that the QDs have an anomalously undulated top surface which is very different to that observed for Stranski-Krastanow grown QDs.

  19. Quantitative analysis in gas chromatography/low power atmospheric-pressure helium microwave-induced plasma atomic emission interferometry and ion cyclotron resonance mass spectroscopy

    SciTech Connect

    Loo, J.F.

    1990-01-01

    The development of experimental and data analysis techniques for quantitative analysis in gas chromatography/low power atmospheric pressure helium microwave-induced plasma atomic emission interferometry (GC/HeMIPAEI) and ion cyclotron resonance mass spectroscopy (ICR/MS) is presented. A discussion of interferometric data analysis by discrete and fast Fourier transform (DFT and FFT, respectively) is given. Additionally, the use of two techniques (the maximum entropy method, or MEM, and linear prediction, or LP) that have shown to produce results superior to those from the FFT is shown for synthetic and experimental NMR, optical, and mass spectral data. Visual spectral comparisons, performance results as compared to known spectral parameters, and a methodology for the implementation of the linear prediction technique is given. A low-power HeMIP was constructed and used as the excitation source for an AEI detector for gas chromatography. In general, HeMIPs have the advantage of being able to excite non-metal atoms, which comprise a large fraction of the molecules used in typical organic GC analysis. Sensitivity, detection limits, their dependence on microwave power values, and elemental emission ratios are tabulated for a series of test compounds. Results show that elemental emission ratios are independent of the structure of the compound used in this study. Suggestions for further development, from the use of a concentric-flow torch and optical filters to the removal of oxygen through the use of ultra-high purity helium, are presented. Through the use of coherent pulsed excitation, electronic quadrature detection, and data analysis by linear prediction, ICR/MS relative abundance error values for the principal isotopes of krypton have been calculated to be less than 1%.

  20. 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.

  1. Thermospray nebulizer as sample introduction technique for microwave plasma torch atomic emission spectrometry 1 This paper was published in the Special Issue from the BCEIA Conference in Shanghai, China, in October 1997. 1

    Microsoft Academic Search

    Chenglong Yang; Zhixia Zhuang; Yi Tu; Pengyuan Yang; Xiaoru Wang

    1998-01-01

    A thermospray nebulizer was used as a sample introduction device for microwave plasma torch (MPT) atomic emission spectrometry (AES). Experimental parameters, including the power supplied to the MPT, the flow rates of support and carrier gases, the observation height, the sample uptake rate, the thermospray working temperature, the temperature of the aerosol spray chamber and cooling water were optimized. Under

  2. 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.

  3. 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.

  4. Simultaneous determination of macro and trace elements in biological reference materials by microwave induced plasma optical emission spectrometry with slurry sample introduction

    NASA Astrophysics Data System (ADS)

    Matusiewicz, Henryk; Golik, Bartosz

    2004-05-01

    A slurry sampling technique (SST) has been utilized for simultaneous multi-element analysis by microwave-induced plasma optical emission spectrometry (MIP-OES). Slurry samples from a spray chamber are fed directly into the microwave cavity-torch assembly (power 300 W) with no desolvation apparatus. The performance of SST-MIP-OES was demonstrated by the determination of macro (Na, K, Ca, Mg, P) and trace (Cd, Cu, Mn, Sr, Zn) elements in three biological certified reference materials using a V-groove, clog-free Babington-type nebulizer. Slurry concentrations up to 1% m/v (particles <20 ?m), prepared in 10% HNO 3 (pH 1.2) containing 0.01% of Triton X-100, were used with calibration by the standard additions method. The method offers relatively good precision (R.S.D. ranged from 7 to 11%) with measured concentrations being in satisfactory agreement with certified values for NRCC TORT-1 (Lobster hepatopancreas), NRCC LUTS-1 (Lobster hepatopancreas) and IAEA-153 (Milk powder). The concentrations of Na, K, Ca, Mg, P and Cd, Cu, Mn, Sr, Zn were determined in the range 90-22 000 ?g/g and 1-420 ?g/g, respectively. The method could be useful as a routine procedure.

  5. A comparative study of three microwave-induced plasma sources for atomic emission spectrometry-II. Evaluation of their atomization/excitation capabilities for chlorinated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Camuña-Aguilar, J. F.; Pereiro-Garcia, R.; Sánchez-Uría, J. E.; Sanz-Medel, A.

    1994-06-01

    A comparative analytical survey of the performance of three different helium microwave-induced plasmas (MIP) for atomic emission spectrometry (AES) has been performed using chlorinated hydrocarbons of growing molecular complexity as models. The cavity structures investigated were a Beenakker cavity, a surfatron and a microwave plasma torch (MPT). Detection limits and linear dynamic ranges for Cl and C, capabilities to obtain element ratio determinations (Cl/C ratios), and tolerance to organic solvents were tested for the different MIP cavities. The effect of O 2 scavenger gas in the surfatron to eliminate carbon deposits was also investigated. Results demonstrated that differences in detection limits (DL) observed for the same element in the three cavities were no higher than 2-3 times. The most sensitive He-MIP source proved to be the Beenakker cavity (with DL of 0.05 ng ml -1 for C and 0.5 ng ml -1 for Cl). The MPT source showed its superiority to withstand high levels of organic compounds and was also the structure that provided better correlation between the theoretical and the experimental element ratios obtained for high hydrocarbon concentrations.

  6. Determination of silver in nano-plastic food packaging by microwave digestion coupled with inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry.

    PubMed

    Lin, Q-B; Li, B; Song, H; Wu, H-J

    2011-08-01

    The detection of silver in nano-plastic food packaging by microwave digestion coupled with either inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Microwave digestion was optimised by trialling different acid mixtures. Both ICP-AES and ICP-MS showed good reproducibility, repeatability and recovery. For ICP-AES the limit of detection of the method (LODm) was 25.0?µg?g(-1), the limit of detection of the instrument (LODi) was 30.0?ng?ml(-1), the linear range was 0.10-10.0?µg?ml(-1). The average recoveries for blank samples spiked with silver at 100, 250 and 500?µg?g(-1) ranged from 82.53% to 87.60%, and the relative standard deviations (RSDs) were from 1.79% to 8.30%. For ICP-MS analysis the LODm was 0.75?µg?g(-1), the LODi was 0.04?ng?ml(-1), the linear range was 0.20-500.0?ng?ml(-1), the RSDs were 2.26-4.79%, and the recoveries were 78.09-92.72% (spiked concentrations of 2.5, 5.0 and 10.0?µg?g(-1)). These results indicate that the proposed method could be employed to analyse silver in nano-plastic food packaging. PMID:21790489

  7. Analyte volatilization procedure for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Nakahara, Taketoshi; Nishida, Takahiro

    1998-08-01

    A simple method is described for the generation of a continuous flow of volatile chlorine by the oxidation of aqueous chloride for the determination of low concentrations of chlorine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (He MIP-AES). The chlorine atom emission line at 438.976 nm and ion emission lines at 479.454 and 481.006 nm were selected as the analytical lines of interest. Of the various oxidation reactions investigated, two analyte volatilization reactions with potassium permanganate and perbromate in combination with sulfuric acid were found to be the most appropriate for the generation of elemental chlorine. The gaseous chlorine is separated from the solution in a simple gas-liquid separator, dried with concentrated sulfuric acid and swept into the MIP with helium carrier gas for analysis. The best attainable detection limits (3 ? criterion) for chlorine at 438.976, 479.454 and 481.006 nm with the use of potassium permanganate as an oxidant were found to be 29.9, 6.8 and 12.3 ng ml -1, respectively. Typical calibration graphs obtained under the optimized experimental conditions are rectilinear over approximately three orders of magnitude of concentration. The present method has successfully been applied to the determination of chlorine as chloride in several water samples.

  8. Attenuation statistics at 20.6, 31.65 and 52.85 GHz derived from emission measurements by ground-based microwave radiometers

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Two seasons (December 1987 to February 1988 and July 1988 to September 1988) of thermal emission measurements, taken by a multichannel 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 at 52.85 GHz. In addition, data from two radiometers located 50 km apart are used to derive two-station attenuation diversity statistics at 20.6 and 31.65 GHz. The multichannel radiometer was operated at Denver, Colorado, U.S. and the dual-channel device was operated at Platteville, Colorado. The diversity statistics are presented by cumulative distributions and by bivariate frequency distributions. The frequency distributions are analyzed when either one or both stations have liquid clouds.

  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. Continuous-flow determination of aqueous sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry with gas-phase sample introduction

    NASA Astrophysics Data System (ADS)

    Nakahara, Taketoshi; Mori, Toshio; Morimoto, Satoru; Ishikawa, Hiroshi

    1995-06-01

    A simple continuous-flow generation of volatile hydrogen sulfide and sulfur dioxide by acidification of aqueous sulfide and sulfite ions, respectively, is described for the determination of low concentrations of sulfur by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (MIP-AES) in the normal ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum. For measuring spectral lines in the VUV region, the monochromator and the enclosed external optical path between the MIP source and the entrance slit of the monochromator have both been purged with nitrogen to minimize oxygen absorption below 190 nm. Sulfur atomic emission lines at 180.73, 182.04 and 217.05 nm have been selected as the analytical lines. Of the various acids examined, 1.0 M hydrochloric acid is the most favorable for both the generation of hydrogen sulfide from sulfide ions and sulfur dioxide from sulfite ions. Either generated hydrogen sulfide or sulfur dioxide is separated from the solution in a simple gas-liquid separator and swept into the helium stream of a microwave-induced plasma for analysis. The best attainable detection limits (3 ? criterion) for sulfur at 180.73 nm were 0.13 and 1.28 ng ml -1 for the generation of hydrogen sulfide and sulfur dioxide, respectively, with the corresponding background equivalent concentrations of 20.9 and 62.2 ng ml -1 in sulfur concentration. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear over approximately four orders of magnitude in sulfur concentration. The present method has been successfully applied to the recovery test of the sulfide spiked to waste water samples and to the determination of sulfite in some samples of commercially available wine.

  11. The DMRT-ML model: numerical simulations of the microwave emission of multilayered snowpacks based on the Dense Media Radiative Transfer theory

    NASA Astrophysics Data System (ADS)

    Picard, G.; Brucker, L.; Roy, A.; Dupont, F.; Fily, M.; Royer, A.; Champollion, N.; Morin, S.

    2012-12-01

    DMRT-ML is a physically-based model to compute the thermal microwave emission of a given snowpack for passive microwave remote sensing applications. The model is based on the Dense Media Radiative Transfer Theory (DMRT) for the computation of snow scattering and absorption properties. The radiative transfer equation is accurately solved using the DIscrete Ordinate Radiative Transfer Method (DISORT). The snowpack is described as a stack of horizontal snow layers and an optional underlying interface representing either the soil or the ice. The atmospheric downwelling contribution can be optionally taken into account. DMRT-ML is designed to work for most snow-covered surfaces, and can account for both dry and wet snowpack conditions over soil (e.g. Alpine or Arctic seasonal snow) and over ice (e.g. on ice sheet or lake). The model was initially validated against satellite observations at Dome C, East Antarctica, using in-situ snow grain size, density and temperature profile measurements. Recently, DMRT-ML was extended and applied to sub-Arctic seasonal snowpacks. Validation experiments were done using a set of 20 detailed snowpit measurements. Results were compared to ground-based radiometry. In addition, the model was applied to snowpacks overlying ice, as found on the Canadian Barnes ice cap and on the ablation areas of Antarctic ice sheets. Accounting for the ice properties (bubble size and density) appeared to be necessary to get the best agreement between the model simulations and the ground-based radiometer observations. This model provides accurate snow brightness temperature simulations over for a wide range of cryospheric environments, which are of particular interest for the assimilation of satellite passive microwave data in snow models and for improving simulations of snow properties. Indeed, the model can take input from a detailed snowpack model such as Crocus or SNOWPACK. It is entirely written in Fortran90 which makes its integration in numerical weather prediction land surface assimilation schemes as seamless as possible. DMRT-ML was publicly released under an open source license in spring 2012. Since then, a broader community of users working with passive microwave in the cryosphere is using the model. The objective of this poster is to describe the DMRT-ML model and present the validations in the sub-Arctic and Arctic.

  12. On-line microwave-based preconcentration device for inductively coupled plasma atomic emission spectrometry: application to the elemental analysis of spirit samples.

    PubMed

    Grindlay, Guillermo; Gras, Luis; Hernandis, Vicente; Mora, Juan

    2013-03-30

    A microwave-based thermal nebulizer (MWTN) has been employed for the first time as on-line preconcentration device in inductively coupled plasma atomic emission spectrometry (ICP-AES). By the appropriate selection of the experimental conditions, the MWTN could be either operated as a conventional thermal nebulizer or as on-line analyte preconcentration and nebulization device. Thus, when operating at microwave power values above 100 W and highly concentrated alcohol solutions, the amount of energy per solvent mass liquid unit (EMR) is high enough to completely evaporate the solvent inside the system and, as a consequence, the analyte is deposited (and then preconcentrated) on the inner walls of the MWTN capillary. When reducing the EMR to the appropriate value (e.g., by reducing the microwave power at a constant sample uptake rate) the retained analyte is swept along by the liquid-gas stream and an analyte-enriched aerosol is generated and next introduced into the plasma cell. Emission signals obtained with the MWTN operating in preconcentration-nebulization mode improved when increasing preconcentration time and sample uptake rate as well as when decreasing the nozzle inner diameter. When running with pure ethanol solution at its optimum experimental conditions, the MWTN in preconcentration-nebulization mode afforded limits of detection up to one order of magnitude lowers than those obtained operating the MWTN exclusively as a nebulizer. To validate the method, the multi-element analysis (i.e. Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb and Zn) of different commercial spirit samples in ICP-AES has been performed. Analyte recoveries for all the elements studied ranged between 93% and 107% and the dynamic linear range covered up to 4 orders of magnitude (i.e. from 0.1 to 1000?gL(-1)). In these analysis, both MWTN operating modes afforded similar results. Nevertheless, the preconcentration-nebulization mode permits to determine a higher number of analytes due to its higher detection capabilities. PMID:23598185

  13. Electric dipole emission by fullerenes and buckyonions

    E-print Network

    Susana Iglesias-Groth

    2005-09-15

    We study the rotation rates and electric dipole emission of hydrogenated icosahedral fullerenes (single and multishell) in various phases of the interstellar medium. Using the formalism of Draine and Lazarian for the rotational dynamics of these molecules in various astrophysical environments, we find effective rotation rates in the range 1-65 GHz with a trend toward lower rotational frequency as the radius of the molecule increases. Owing to the moderately polar nature of the C--H bond, hydrogenated fullerenes (fulleranes) are expected to have a net dipole moment and produce electric dipole radiation. Adopting the same size distribution proposed for fullerenes in the study of the UV extinction bump (2175 \\AA) we predict the dipole electric emission of mixtures of fulleranes for various levels of hydrogenation. We find that these molecules could be the carriers of the anomalous microwave emission recently detected by Watson et al. in the Perseus molecular complex.

  14. Performance of a microwave induced plasma (MIP) operated in a liquid-cooled discharge tube for atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Mierzwa, J.; Brandt, R.; Broekaert, J. A. C.; Tschöpel, P.; Tölg, G.

    1996-01-01

    Different types of microwave induced plasma (MIP) discharge operated in liquid-cooled tubes, namely a glass tube of Duran ®, a quartz tube of Herasil ®, and a very simple demountable discharge tube made of glass and quartz have been investigated. The last tube leads to the best analytical properties and the longest lifetime. The intensities of silicon lines and of the continuum spectral background, together with the signal-to-background ratios for B, Ca, Cd, Co and Zn in the case of the pneumatic nebulization of solutions have been measured and used as an indicator for the cooling efficiency. The MIP torch was cooled with a thermostated silicon oil. The decrease of the temperature of the cooling medium causes a measurable decrease of the spectral background intensity. Diagnostic measurements of the plasma include radial profiles of spectral line intensities and excitation temperatures with the lines of Fe I; values of 5000-6000 K are found. The influence of different plasma parameters, e.g. microwave power and helium flow rate, is investigated. The preliminary analytical characterization of a helium MIP maintained with the liquid-cooled demountable discharge tube is presented. Limits of detection for Al, B, Ca, Co, Fe, P, Sb and Zn (between 0.002 and 1.2 ?g ml -1) are comparable with or better than those reported for low power helium MIPs with sample introduction in the form of a wet aerosol.

  15. The influence of ions and the induced secondary emission on the nanosecond high-gradient microwave breakdown at metal surface

    NASA Astrophysics Data System (ADS)

    Chang, C.; Liu, C. L.; Chen, C. H.; Sun, J.; Liu, Y. S.; Guo, L. T.; Cao, Y. B.; Wang, Y.; Song, Z. M.

    2015-06-01

    The mechanism of ultrafast breakdown at metal/vacuum interface in the high-power microwave waveguides is studied. In order to realize the nanosecond discharge, the required ambient gas pressure above the metal surface is approximately calculated as high as several Torr due to the low ionization-rate for high-energy electrons and short pulse. The local high pressure may come from the evaporated microscopic protrusions due to Joule heating and gas desorption. Besides, ions accelerated by the ambient space charge field could obtain sufficient high energy to collide and sputter the metal atoms to increase the ambient pressure. The positive feedbacks during the rapid discharge are studied by particle-in-cell simulation. The relatively high-energy ions could generate secondary electrons. It is shown that, as the positive feedback, the secondary electrons induce the gas desorption and stronger ionization, resulting in ion and electron density increasing as well as sheath field further increasing. As a result, more higher-energy ions bombard metal surface, leading to higher secondary electron yield and higher density plasma generated to cut off the microwave transmission finally. These nonlinear courses realize the ultrafast discharge in waveguides.

  16. Hanbit microwave plasma diagnostic system

    Microsoft Academic Search

    B. C. Kim; K. D. Lee; S. M. Hwang; G. S. Lee; K. H. Chung

    1999-01-01

    As a part of the plasma diagnostic system for the Hanbit device, various microwave plasma diagnostic systems have been designed and developed from the initial stage of the Hanbit project. These include the interferometer, reflectometer, and electron cyclotron emission radiometer. In this work, we present the current activities related to the development of the microwave diagnostic systems. The brief descriptions

  17. 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.

  18. A multi-frequency measurement of thermal microwave emission from soils: The effects of soil texture and surface roughness

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Oneill, P. E.; Jackson, T. J.; Engman, E. T. (principal investigators)

    1981-01-01

    An experiment on remote sensing of soil moisture content was conducted over bare fields with microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz during July - September of 1981. Three bare fields with different surface roughnesses and soil textures were prepared for the experiment. Ground truth acquisition of soil temperatures and moisture contents for 5 layers down to the depths of 15 cm was made concurrently with radiometric measurements. The experimental results show that the effect of surface roughness is to increase the soils' brightness temperature and to reduce the slope of regression between brightness temperature and moisture content. The slopes of regression for soils with different textures are found to be comparable, and the effect of soil texture is reflected in the difference of regression line intercepts at brightness temperature axis. The result is consistent with laboratory measurement of soils' dielectric permittivity. Measurements on wet smooth bare fields give lower brightness temperatures at 5 GHz than at 1.4 GHz.

  19. Microwave Ovens

    MedlinePLUS

    ... pdf format ] This page describes the type of electromagnetic radiation emitted by microwave ovens. On this page: Overview ... it very quickly. Microwaves are a form of electromagnetic radiation; that is, they are waves of electrical and ...

  20. The Detection of a Striking Increase in the Microwave Emission from Jupiter's Radiation Belts in June and July 2003

    Microsoft Academic Search

    M. J. Klein; S. J. Bolton; S. M. Levin; D. Mac Laren

    2004-01-01

    Synchrotron emission from energetic electrons in Jupiter's radiation belts has been routinely measured by ground-based radio telescopes for three decades. The NASA-JPL Jupiter Patrol, using NASA's Deep Space Network (DSN) antennas at Goldstone, CA., has reported significant (5 %-to-30 %) variations in Jupiter's flux density near 13-cm wavelength with timescales from a few days to several months. In this paper

  1. Evaluation of different derivatization methods for the multi-element detection of Hg, Pb and Sn compounds by gas chromatography-microwave induced plasma-atomic emission spectrometry in environmental samples

    Microsoft Academic Search

    V. Minganti; R. Capelli; R. De Pellegrini

    1995-01-01

    A multi-element, element-specific detector for gas chromatography (GC) based on atomic emission spectroscopy (AES) with a microwave induced plasma (MIP) source was tested on some environmental samples. As derivatization procedure, direct aqueous phase ethylation and chelation\\/extraction followed by Grignard reaction were tested on the following ions: methylmercury, ethylmercury, phenylmercury, mercury(II), trimethyllead, dimethyllead, lead(II), trimethyltin, dimethyltin, triethyltin, tripropyltin, tributyltin, dibutyltin, butyltin,

  2. Evaluation of a purge-and-trap injection system for capillary gas chromatography-microwave induced plasma-atomic emission spectrometry for the determination of volatile selenium compounds in water

    Microsoft Academic Search

    María Beatriz de la Calle Guntiñas; Michiel Ceulemans; Claudia Witte; Ryszard ?obi?ski; Freddy C. Adams

    1995-01-01

    A method is presented for the selective determination of the volatile selenium species dimethylselenide and dimethyldiselenide, using a commercially available purge-and-trap injection system coupled to capillary gas chromatography-microwave induced plasma-atomic emission spectrometry. The efficiency of the purging step was evaluated and the parameters affecting the purge and trap processes were optimized. The method was applied to the determination of volatile

  3. Flow injection on-line preconcentration with an ion-exchange resin coupled with microwave plasma torch-atomic emission spectrometry for the determination of trace rare earth elements

    Microsoft Academic Search

    Qiong Jia; Xiangfei Kong; Weihong Zhou; Lihua Bi

    2008-01-01

    A sensitive and rapid on-line method has been developed for the determination of trace amounts rare earth elements (REEs), lanthanum, cerium, neodymium and yttrium, by microwave plasma torch-atomic emission spectrometry (MPT-AES) combined with micro-column separation\\/preconcentration. A strong basic cinnamene anion exchange resin is used for matrix elimination and enrichment of the analytes. The adsorbed metal ions are subsequently eluted from

  4. Microwave plasma torch-atomic emission spectrometry for the on-line determination of rare earth elements based on flow injection preconcentration by TiO 2–graphene composite

    Microsoft Academic Search

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

    2011-01-01

    In this work, we synthesized TiO2–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,

  5. 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.

  6. Multielement determination of heavy metals in water samples by continuous powder introduction microwave-induced plasma atomic emission spectrometry after preconcentration on activated carbon

    NASA Astrophysics Data System (ADS)

    Jankowski, Krzysztof; Yao, Jun; Kasiura, Krzysztof; Jackowska, Adrianna; Sieradzka, Anna

    2005-03-01

    A novel continuous powder introduction microwave-induced plasma atomic emission spectrometry method (CPI-MIP-AES) has been developed for trace determination of metals in ground and tap water samples after preconcentration on activated carbon. The experimental setup consisted of integrated rectangular cavity TE 101 and vertically positioned plasma torch. The technical arrangement of the sample introduction system has been designed based on the fluidized bed concept. The satisfactory signal stability required for sequential analysis was attained owing to the vertical plasma configuration, as well as the plasma gas flow rate compatibility with sample introduction flow rate. The elements of interest (Cd, Cu, Cr, Fe, Mn, Pb, Zn) were preconcentrated in a batch procedure at pH 8-8.5 after addition of activated carbon and then, after filtering and drying of the activated carbon suspension, introduced to the MIP by the CPI system. An enrichment factor of about 1000-fold for a sample volume of 1 l was obtained. The detection limit values for the proposed method were 17-250 ng l -1. The proposed method was validated by analyzing the certified reference materials: SRW "Warta" Synthetic River Water and BCR CRM 399 major elements in freshwater. The method was successfully applied to the determination of the heavy metals in tap water samples.

  7. Optimization of an open-focused microwave oven digestion procedure for determination of metals in diesel oil by inductively coupled plasma optical emission spectrometry.

    PubMed

    Sant'Ana, Flavio W; Santelli, Ricardo E; Cassella, Alessandra R; Cassella, Ricardo J

    2007-10-01

    This work reports the optimization of a focused microwave assisted procedure for the wet acid dissolution of diesel oil in order to allow the determination of metals in the samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The dissolution process was monitored by measuring residual carbon content (RCC), also by ICP-OES, in the final solutions obtained after application of digestion program. All experimental work was performed using a commercial sample of diesel oil containing 85.74+/-0.13% of carbon. The initial dissolution program comprised three steps: (i) carbonization with H(2)SO(4); (ii) oxidation with HNO(3) and (iii) final oxidation with H(2)O(2). During work it was verified that the first step played an important role on the dissolution process of this kind of sample. It is therefore, necessary to give a detailed optimization of such step. Employing the optimized conditions it was possible to digest 2.5 g of diesel oil with a 40 min-heating program. At these conditions, residual carbon content was always lower than 5%. Optimized methodology was applied in the determination of metals in three diesel oil samples by ICP-OES. Recovery tests were also performed by adding 10 microg of metals, as organic standards, to the samples before digestion. Recovery percentages always higher than 90% were obtained for the metals of interest (Al, Cu, Fe and Ni), except for Zn, which presented recoveries between 70 and 78%. PMID:17509759

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

    NASA Astrophysics Data System (ADS)

    Tiwari, Rajanish N.; Chang, Li

    2010-05-01

    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 {100} 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 ˜530 °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/?m) and high current-density (1.6 mA/cm2) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

  9. Solution nebulization into a low-power argon microwave-induced plasma for atomic emission spectrometry: study of synthetic ocean water

    SciTech Connect

    Ng, K.C.; Shen, W.

    1986-08-01

    A MAK nebulizer is used to introduce liquid aerosols containing Cr, Mn, In, V, Pb, Sr, or Zr into a low-power (105-115 W), low argon flow (537 mL/min) microwave-induced plasma for atomic emission spectrometry. Detection limits (3sigma) in 3% nitric acid water samples are at the parts-per-billion level (62, 18, 18, 91, 139, 13, and 3945, respectively). These values compared favorably to those reported for a 150-W Ar-MIP and the conventional inductively coupled plasma for most of the elements. In a 10% synthetic ocean water matrix, signal enhancement is obtained for Cr, Mn, In, Pb, and Sr, and signal depression is found for V and Zr. Detection limits (parts per billion) in the 10% ocean water are 9, 3, 6, 1780, 54, 2, and not measurable, for Cr, Mn, In, V, Pb, Sr, and Zr, respectively. The signal precision is typically 2% RSD for 1 ppm solutions. Linear responses (>3 orders of magnitude) are associated with all of the tested analyte concentrations of water or synthetic ocean matrices.

  10. 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.

  11. 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.

  12. Magnetic Nanoparticles in the Interstellar Medium: Emission Spectrum and Polarization

    NASA Astrophysics Data System (ADS)

    Draine, B. T.; Hensley, Brandon

    2013-03-01

    The presence of ferromagnetic or ferrimagnetic nanoparticles in the interstellar medium would give rise to magnetic dipole radiation at microwave and submillimeter frequencies. Such grains may account for the strong millimeter-wavelength emission observed from a number of low-metallicity galaxies, including the Small Magellanic Cloud. We calculate the absorption and scattering cross sections for such grains, with particular attention to metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, all potentially present in the interstellar medium. The rate of Davis-Greenstein alignment by magnetic dissipation is also estimated. We determine the temperature of free-flying magnetic grains heated by starlight and calculate the polarization of the magnetic dipole emission from both free-fliers and inclusions. For inclusions, the magnetic dipole emission is expected to be polarized orthogonally relative to the normal electric dipole radiation. Magnetic dipole radiation will contribute significantly to the 20-40 GHz anomalous microwave emission only if a large fraction of the Fe is in metallic Fe iron nanoparticles with extreme elongations. Finally, we present self-consistent dielectric functions for metallic Fe, magnetite Fe3O4, and maghemite ?-Fe2O3, enabling calculation of absorption and scattering cross sections from microwave to X-ray wavelengths.

  13. MAGNETIC NANOPARTICLES IN THE INTERSTELLAR MEDIUM: EMISSION SPECTRUM AND POLARIZATION

    SciTech Connect

    Draine, B. T.; Hensley, Brandon, E-mail: draine@astro.princeton.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States)

    2013-03-10

    The presence of ferromagnetic or ferrimagnetic nanoparticles in the interstellar medium would give rise to magnetic dipole radiation at microwave and submillimeter frequencies. Such grains may account for the strong millimeter-wavelength emission observed from a number of low-metallicity galaxies, including the Small Magellanic Cloud. We calculate the absorption and scattering cross sections for such grains, with particular attention to metallic Fe, magnetite Fe{sub 3}O{sub 4}, and maghemite {gamma}-Fe{sub 2}O{sub 3}, all potentially present in the interstellar medium. The rate of Davis-Greenstein alignment by magnetic dissipation is also estimated. We determine the temperature of free-flying magnetic grains heated by starlight and calculate the polarization of the magnetic dipole emission from both free-fliers and inclusions. For inclusions, the magnetic dipole emission is expected to be polarized orthogonally relative to the normal electric dipole radiation. Magnetic dipole radiation will contribute significantly to the 20-40 GHz anomalous microwave emission only if a large fraction of the Fe is in metallic Fe iron nanoparticles with extreme elongations. Finally, we present self-consistent dielectric functions for metallic Fe, magnetite Fe{sub 3}O{sub 4}, and maghemite {gamma}-Fe{sub 2}O{sub 3}, enabling calculation of absorption and scattering cross sections from microwave to X-ray wavelengths.

  14. A search for pulsed radio emission from anomalous X-ray pulsar 4U 0142+61 at the frequency of 111 MHz

    E-print Network

    Alexander A. Ershov; Yurii P. Shitov

    2007-10-11

    We have searched for pulsed radio emission from magnetar 4U 0142+61 at the frequency of 111 MHz. No pulsed signal was detected from this source. Upper limits for mean flux density are 0.9 - 9 mJy depending on assumed duty cycle (.05 - .5) of the pulsar.

  15. 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.

  16. Implications of the IBEX observation of ribbon in energetic neutral atom emissions to the transport of Galactic and anomalous cosmic rays near the heliopause

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Gamayunov, K. V.; Rassoul, H.; Pogorelov, N. V.; Heerikhuisen, J.

    2013-12-01

    The first IBEX all-sky image of energetic neutral atoms discovered a ribbon structure located around the arc where the line of slight is perpendicular to the draped interstellar magnetic field in the outer heliosheath. The most plausible explanation to the ribbon is the Heerikhuisen et al. (2010) model in which the neutral solar wind, produced in the inner heliosphere by charge exchange between the solar wind and interstellar neutral atoms, propagates freely to the outer heliosheath, where they are ionized to become pickup ions through charge exchange, turned around by the magnetic field, and then become neutral atoms again, which can freely propagate back to the Earth. In order for this mechanism to work, the turbulence in the outer heliosheath must be very low to inhibit scattering of the intermediate pickup ions there (Gamayunov et al. 2010). On the other hand, the magnetic field turbulence in the inner heliosheath is quite large under the influence of the solar wind termination shock. The contrast of turbulence properties across the heliopause must imply a large disparity in the behavior of energetic particle transport: Small perpendicular diffusion and large parallel diffusion is expected outside the heliospause, while the opposite is expected inside the heliopause. This will affect the transport of cosmic rays greatly. Anomalous cosmic rays will quickly be shut off beyond the heliopause and the intensity or gradient of Galactic cosmic rays will see a sudden change. The result also will give us a hope that we may see a pristine interstellar cosmic ray spectrum soon after the heliospause crossing. In this paper we will present a detailed simulation of cosmic ray propagation in a MHD model heliosphere with the new configuration of magnetic turbulence.

  17. 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.

  18. 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.

  19. A Possible Explanation of Anomalous Earth Flybys

    E-print Network

    Petry, Walter

    2008-01-01

    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.

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

    SciTech Connect

    Leutenegger, M. A.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Beiersdorfer, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Space Sciences Laboratory, University of California, Berkeley, California 96720 (United States); Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2010-08-06

    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 2 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.

  1. 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.

  2. Evaluation of continuous hydride generation combined with helium and argon microwave induced plasmas using a surfatron for atomic emission spectrometric determination of arsenic, antimony and selenium

    NASA Astrophysics Data System (ADS)

    Yang, Jinfu; Schickling, C.; Broekaert, J. A. C.; Tschöpel, P.; Tölg, G.

    1995-09-01

    The direct coupling of continuous hydride generation with both Ar and He microwave induced plasmas (MIP) sustained in a surfatron has been optimized for the simultaneous determination of arsenic, antimony and selenium with atomic emission spectrometry. While a discharge tube of quartz was found suitable for the Ar plasma, the use of an Al 2O 3 tube led to improved performance of the He plasma. The He MIP was found to be less tolerant to the introduction of hydrogen than the Ar MIP, and correspondingly the hydride generation should be operated at a lower flow rate of 0.5% NaBH 4 solution. The introduction of the H 2O vapour produced during hydride generation into both discharges was found to greatly decrease the sensitivities and to degrade the measurement precision. It could be effectively removed with trapping by concentrated H 2SO 4. The detection limits (3?) for As, Sb and Se are 1, 0.4 and 1 ng ml -1 with the Ar MIP, and 2, 0.3 and 6 ng ml -1 with the He MIP, respectively. The calibration curves are linear over three decades of concentration. The mutual interferences from As(III), Sb(III), Se(IV), Bi(III) and Sn(IV) were found to be negligible at interferent concentrations below 1 ?g ml -1 and in most cases the tolerable interferent concentrations are up to 20 ?g ml -1. The proposed method has been applied to the determination of As, Sb and Se in tea samples at ?g g -1 levels.

  3. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-Ray Pulsar 1E 1841-045

    NASA Technical Reports Server (NTRS)

    Lin, Lin; Kouveliotou, Chryssa; Gogus, Ersin; van der Horst, Alexander J.; Watts, Anna L.; Baring, Matthew G.; Kaneko, Yuki; Wijers, Ralph A. M. J.; Woods, Peter M.; Barthelmy, Scott; Burgess, J. Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D.; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    SWift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18 - 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 1038 erg, which is in the low side of SGR 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 IE 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  4. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-ray Pulsar 1E 1841-045

    E-print Network

    Lin, Lin; Gogus, Ersin; van der Horst, Alexander J; Watts, Anna L; Baring, Matthew G; Kaneko, Yuki; Wijers, Ralph A M J; Woods, Peter M; Barthelmy, Scott; Burgess, J Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    Swift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18-140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8 - 25)E38 erg, which is in the low side of SGR 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.

  5. Observational and theoretical advances in cosmological foreground emission

    NASA Astrophysics Data System (ADS)

    Stevenson, Matthew A.

    Observational and theoretical work towards the separation of foreground emission from the cosmic microwave background is described. The bulk of this work is in the design, construction, and commissioning of the C-Band All-Sky Survey (C-BASS), an experiment to produce a template of the Milky Way Galaxy's polarized synchrotron emission. Theoretical work is the derivation of an analytical approximation to the emission spectrum of spinning dust grains. The performance of the C-BASS experiment is demonstrated through a preliminary, deep survey of the North Celestial Pole region. A comparison to multiwavelength data is performed, and the thermal and systematic noise properties of the experiment are explored. The systematic noise has been minimized through careful data processing algorithms, implemented both in the experiment's Field Programmable Gate Array (FPGA) based digital backend and in the data analysis pipeline. Detailed descriptions of these algorithms are presented. The analytical function of spinning dust emission is derived through the application of careful approximations, with each step tested against numerical calculations. This work is intended for use in the parameterized separation of cosmological foreground components and as a framework for interpreting and comparing the variety of anomalous microwave emission observations.

  6. Methylmercury determination in biological samples by derivatization, solid-phase microextraction and gas chromatography with microwave-induced plasma atomic emission spectrometry

    Microsoft Academic Search

    R Rodil; A. M Carro; R. A Lorenzo; M Abu??n; R Cela

    2002-01-01

    A method for the extraction and gas chromatographic determination of methylmercury in biological matrices is presented. By combining the advantages of two extraction techniques—microwave-assisted extraction (MAE) and solid-phase microextraction (SPME)—the separation of methylmercury from biological samples is possible. Specifically, the procedure involves microwave extraction with 3 M hydrochloric acid, followed by aqueous-phase derivatization with sodium tetraphenylborate and headspace SPME with

  7. Anomalous optical Bloch oscillations

    NASA Astrophysics Data System (ADS)

    Gozman, M. I.; Polishchuk, Yu. I.; Polishchuk, I. Ya.; Tsivkunova, E. A.

    2015-07-01

    Anomalous optical Bloch oscillation in waveguide arrays are investigated within the generalized Coupling Mode Model (CMM). This model takes into account the next neighbor interaction between the waveguides along with the nearest neighbor interaction. The exact analytical solution for the optical beam path is found. A criterion of the appearance of the anomalous Bloch oscillations against the standard Bloch oscillations background is discovered. A comparison between the analytical result and the numerical simulation reveals a good agreement.

  8. 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.

  9. 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...

  10. Emissions and photocatalytic selectivity of SrWO4:Ln3+ (Eu3+, Tb3+, Sm3+ and Dy3+) prepared by a supersonic microwave co-assistance method.

    PubMed

    Zheng, Yuhui; Lin, Jintai; Wang, Qianming

    2012-10-01

    The chemical effects of high intensity ultrasound and microwave irradiation on lanthanide (Eu(3+), Tb(3+), Sm(3+) and Dy(3+)) activated SrWO(4) phosphors were extensively studied. Four classes of characteristic optically active materials (red, green, orange-red and blue-yellow) with striking luminescence were facilely prepared under very low temperature (70 °C) in 45 min. Particularly, Sm(3+), Dy(3+) and Eu(3+) doped strontium tungstates were visible-light driven emissive. The photocatalytic properties of these luminescent lanthanide doped tungstates were systematically examined by investigating the degradation behavior of different dyes. PMID:22854656

  11. Explosive Emission Cathode Based on a Carbon Fiber for Long-Term Pulsed-Periodic Mode of Operation and its Application in a High-Power Microwave Pulse Generator Without External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kutenkov, O. P.; Pegel, I. V.; Totmeninov, E. M.

    2014-09-01

    Current characteristics and operating lifetime of the explosive emission cathode based on a carbon microfiber are investigated in the pulsed-periodic mode of operation with pulse duration of about 5 ns. Long-term (for up to 3.6 million pulses) tests of the cathode operating lifetime are carried out. Specific ablation of the fiber material equal to 2.4·10-4 g/C is obtained. Change in the morphology of the fiber surface during long-time operation caused by deposition of carbon from the cathode plasma is revealed. The microscopic electric field strength on the fiber surface is estimated taking into account the surface microrelief. The efficiency of microwave generation comparable with that of a velvet cathode in low (200 kV/cm) average electric field in the gap is obtained for the Cherenkov microwave generator with vacuum diode without external magnetic field of decimeter wavelength range based on the SINUS-7 pulsed-periodic high-current electron accelerator with current pulse duration of 50 ns. The operating lifetime no less than 105 pulses is demonstrated for the carbon fiber-based cathode of the microwave generator operating in the mode of pulse batch with duration of several seconds and pulse repetition frequency of 20-50 Hz.

  12. Determination of bis-carboxyethyl germanium sesquioxide by gas chromatography with microwave-induced plasma-atomic emission detection after derivatization with alkyl chloroformates.

    PubMed

    Trikas, E; Zachariadis, G A; Rosenberg, E

    2014-05-01

    Organic germanium compounds, especially Ge-132, more corrctly denoted as bis-beta-carboxyethyl germanium sesquioxide ([Ge(=O)CH2CH2CO2H]2O), are of continued interest as they are said to promote health and display anticancer activity. Although these beneficial effects have never been substantiated by comprehensive clinical studies, this drug can still be obtained through various sources and is usually marketed as a nutritional supplementation rather than an anticancer medication. As the quality standards under which this drug is produced are unknown, the need for an effective quality control of these products arises. To date, Ge-132 is considered generally as a safe compound for application in contrast to inorganic germanium which demonstrates severe renal toxicity. In this paper, a new approach to the determination of Ge-132, based on derivatization by ethyl chloroformate reagent (ECF), in the presence of ethanol and pyridine in the mixture, and subsequent analysis by gas chromatography coupled with microwave-induced plasma-atomic emission detection (GC-MIP-AED), is reported. Reaction conditions of the derivatization procedure were optimized with particular respect to the reagent (ECF) and catalyst (pyridine) concentrations. The proposed method is capable of distinguishing Ge-132 from inorganic germanium. The derivatization procedure was also tested with the use of methyl chloroformate (MCF) as alternative reagent, providing interesting additional information about the nature of the final product and the proposed reaction scheme. Among the two types of chloroformates, i.e., MCF and ECF, the latter proved to be more suitable for the proposed method, providing a calibration curve of superior sensitivity and linearity compared with the one obtained with MCF. The method was applied successfully in three real samples, two food supplements, and one commercially available fertilizer. The analysis of the Ge-132 derivative showed good linearity in the concentration of 1-250 mg L(-1) (r (2)?=?0.9986) and a satisfactory precision (RSD?=?6.8%), which qualifies the proposed method for the speciation analysis of Ge in various matrices. PMID:24748447

  13. Validation of UARS Microwave Limb Sounder ozone

    Microsoft Academic Search

    L. Froidevaux; W. G. Read; T. A. Lungu; R. E. Coileld; E. F. Fishbein; D. A. Flower; R. F. Jarnot; B. P. Ridenoure; Z. Shippony; J. W. Waters; J. J. Margitan; I. S. McDermid; R. A. Stachnik; G. E. Peckham

    1996-01-01

    This paper describes the validation of ozone data from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS). The MLS ozone retrievals are obtained from the calibrated microwave radiances (emission spectra) in two separate bands, at frequencies near 205 and 183 GHz. Analyses described here focus on the MLS Version 3 data (the first set of files made publicly

  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. Observations and interpretation of solar flares at microwave frequencies

    Microsoft Academic Search

    C. J. Crannell; G. A. Dulk; T. Kosugi; A. Magun

    1988-01-01

    The physical processes responsible for microwave emission in solar flares are outlined, and examples of how microwave observations have been interpreted in terms of physical parameters are described. Selected results obtained during Solar Cycle 21 with the microwave observatories dedicated to synoptic observations of the Sun are summarized. The status and future plans for these facilities at Bern and in

  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. Anomalous pulmonary venous connections.

    PubMed

    Katre, Rashmi; Burns, Stephanie K; Murillo, Horacio; Lane, Michael J; Restrepo, Carlos S

    2012-12-01

    Developmental lung anomalies are classified into 3 main categories: bronchopulmonary (lung bud) anomalies, vascular anomalies, and combined lung and vascular anomalies. These anomalies are uncommon, and patients are at times asymptomatic; hence, identifying a developmental lung anomaly in the adult can be a challenge. Pulmonary vascular anomalies include interruption or absence of the main pulmonary artery, anomalous origin of the left pulmonary artery from the right pulmonary artery, anomalous pulmonary venous drainage (partial or complete), and pulmonary arteriovenous malformations. Systemic vascular anomalies comprise persistent left superior vena cava, anomalies of azygos and hemiazygos systems, and anomalies of the thoracic aorta and its major branches. In this article, we present embryology, classification, epidemiology, clinical presentation, and imaging features of anomalous pulmonary venous connections, with special emphasis on multidetector computed tomography and magnetic resonance imaging. These state-of-art imaging techniques have facilitated accurate and prompt diagnosis of these anomalies. PMID:23168060

  18. Applicability of microwave acid digestion to sample preparation of biological materials for analysis by particle-induced X-ray emission (PIXE).

    PubMed

    Pinheiro, T; Duflou, H; Maenhaut, W

    1990-01-01

    A microwave acid digestion method for the preparation of biological samples for PIXE analysis is presented. The precision and accuracy of the entire PIXE analytical procedure, including the microwave digestion step, were evaluated by analyzing eight certified reference materials. For elements heavier than K, and for concentration levels from 2 micrograms/g upward, the total random error of a single analysis is in the range of 2-5%. The accuracy is better than 5%. The detection limits are down to 0.3 micrograms/g. PMID:1704766

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

    E-print Network

    Guedel, Manuel

    as thermal radiations of coronal plasmas. On the other hand, the microwave emission of stars and solar flares. Some coronae of active stars of late spectral type are detected microwave sources. The microwaveThe Soft X­Ray/Microwave Ratio of Solar and Stellar Flares and Coronae A. O. Benz Institute

  20. Galactic foreground contributions to the 5-year Wilkinson Microwave Anisotropy Probe maps

    NASA Astrophysics Data System (ADS)

    Macellari, N.; Pierpaoli, E.; Dickinson, C.; Vaillancourt, J. E.

    2011-12-01

    We compute the cross-correlation between intensity and polarization from the 5-year Wilkinson Microwave Anisotropy Probe (WMAP5) data in different sky regions with respect to template maps for synchrotron, dust and free-free emission. We derive the frequency dependence and polarization fraction for all three components in 48 different sky regions of HEALPIX (Nside= 2) pixelization. The anomalous emission associated with dust is clearly detected in intensity over the entire sky at the K (23-GHz) and Ka (33-GHz) WMAP bands, and is found to be the dominant foreground at low Galactic latitudes, between b =-40° and +10°. The synchrotron spectral index obtained from the K and Ka WMAP bands from an all-sky analysis is ?s=-3.32 ± 0.12 for intensity and ?s=-3.01 ± 0.03 for polarized intensity. The polarization fraction of the synchrotron emission is constant in frequency and increases with latitude from ?5 per cent near the Galactic plane up to ?40 per cent in some regions at high latitudes; the average value for |b| < 20° is 8.6 ± 1.7 (stat) ± 0.5 (sys) per cent, while for |b| > 20°, it is 19.3 ± 0.8 (stat) ± 0.5 (sys) per cent. Anomalous dust and free-free emissions appear to be relatively unpolarized. Monte Carlo simulations showed that there were biases of the method due to cross-talk between the components, at up to ?5 per cent in any given pixel, and ?1.5 per cent on average, when the true polarization fraction is low (a few per cent or less). Nevertheless, the average polarization fraction of dust-correlated emission at the K band is 3.2 ± 0.9 (stat) ± 1.5 (sys) per cent or less than 5 per cent at 95 per cent confidence. When comparing real data with simulations, eight regions show a detected polarization above the 99th percentile of the distribution from simulations with no input foreground polarization, six of which are detected at above 2? and display polarization fractions between 2.6 and 7.2 per cent, except for one anomalous region, which has 32 ± 12 per cent. The dust polarization values are consistent with the expectation from spinning dust emission, but polarized dust emission from magnetic-dipole radiation cannot be ruled out. Free-free emission was found to be unpolarized with an upper limit of 3.4 per cent at 95 per cent confidence.

  1. 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.

  2. 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

  3. A review of microwave oven safety.

    PubMed

    Osepchuk, J M

    1978-03-01

    The microwave leakage from current microwave ovens, which are manufactured to meet government emission standards, is reviewed. Typical leakage values imply exposure values well below the most conservative exposure standards in the world. A review of recent developments discloses increasingly stringent government regulation along with advances in techniques for suppression of microwave leakage. The nature of the leakage field is described and studies relating emission to exposure are reviewed. Field survey data are reviewed and it is found that the overwhelming majority of certified ovens in the field show leakage well below permissible limits with an increasing degree of certainty as time goes on. The conclusion is that microwave ovens are not only just as safe as they were in 1973 but they are being accepted as safe under essentially equivalent emission regulations in various countries including those in Eastern Europe. PMID:251202

  4. Active microwaves

    NASA Technical Reports Server (NTRS)

    Evans, D.; Vidal-Madjar, D.

    1994-01-01

    Research on the use of active microwaves in remote sensing, presented during plenary and poster sessions, is summarized. The main highlights are: calibration techniques are well understood; innovative modeling approaches have been developed which increase active microwave applications (segmentation prior to model inversion, use of ERS-1 scatterometer, simulations); polarization angle and frequency diversity improves characterization of ice sheets, vegetation, and determination of soil moisture (X band sensor study); SAR (Synthetic Aperture Radar) interferometry potential is emerging; use of multiple sensors/extended spectral signatures is important (increase emphasis).

  5. 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

  6. Determination of halides by microwave induced plasma and stabilized capacitive plasma atomic emission spectrometry after on-line continuous halogen generation

    Microsoft Academic Search

    J. F. Camuña; M. Montes; R. Pereiro; A. Sanz-Medel; C. Katschthaler; R. Gross; G. Knapp

    1997-01-01

    This paper describes a comparative study of the microwave induced plasma (MIP) and the stabilized capacitive plasma (SCP) for halide determinations. The MIP is generated in a Beenakker cavity TM010 using a tangential flow torch and the SCP consists of a 27.12 MHz discharge sustained in a liquid-cooled, fused silica tube surrounded by two annular electrodes. Both discharges are operated

  7. Microcolumn preconcentration and gas chromatography-microwave induced plasma-atomic emission spectrometry (GC-MIP-AES) for mercury speciation in waters

    Microsoft Academic Search

    M. L. Mena; C. W. McLeod; P. Jones; A. Withers; V. Minganti; R. Capelli; P. Quevauviller

    1995-01-01

    A novel method for the direct determination of mercury species at the ng l-1 level in natural waters is described. Methyl-, ethyl- and inorganic mercury are preconcentrated on a sulphhydryl cotton microcolumn incorporated in a flow injection system. Retained mercury species are then eluted with hydrochloric acid solution (3 mol\\/l) and subjected to phenylation before determination by gas chromatography-microwave induced

  8. Observation of plasma waves with anomalously weak damping in a two-dimensional electron system

    NASA Astrophysics Data System (ADS)

    Gusikhin, P. A.; Murav'ev, V. M.; Kukushkin, I. V.

    2015-01-01

    The microwave absorption spectra of a stripe of two-dimensional electrons in a GaAs/AlGaAs heterostructure are investigated using the optical detection of microwave absorption. A previously unknown low-frequency microwave-absorption resonance corresponding to the excitation of a weakly damped plasma wave in the two-dimensional electron system is observed. The new plasma mode is anomalously narrow, its width being considerably smaller than the inverse relaxation time of two-dimensional electrons. The measured dependences of the frequency of this mode on the density of two-dimensional electrons and the magnetic field give evidence of its plasmon-polariton nature.

  9. Microwave superconductivity

    Microsoft Academic Search

    Raafat R. Mansour

    2002-01-01

    This paper provides an overview of the microwave applications of high-temperature superconductor (HTS) technology. The main characteristics of HTS materials are outlined, highlighting the differences between superconductors and normal conductors. This paper presents recent progress in the development of HTS filters, multiplexers, cryogenic receivers, delay lines, and antennas. A brief summary of cryocooler technology and cryopackaging requirements is presented. The

  10. Improvement of AOAC Official Method 984.27 for the determination of nine nutritional elements in food products by Inductively coupled plasma-atomic emission spectroscopy after microwave digestion: single-laboratory validation and ring trial.

    PubMed

    Poitevin, Eric; Nicolas, Marine; Graveleau, Laetitia; Richoz, Janique; Andrey, Daniel; Monard, Florence

    2009-01-01

    A single-laboratory validation (SLV) and a ring trial (RT) were undertaken to determine nine nutritional elements in food products by inductively coupled plasma-atomic emission spectroscopy in order to improve and update AOAC Official Method 984.27. The improvements involved optimized microwave digestion, selected analytical lines, internal standardization, and ion buffering. Simultaneous determination of nine elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, and zinc) was made in food products. Sample digestion was performed through wet digestion of food samples by microwave technology with either closed or open vessel systems. Validation was performed to characterize the method for selectivity, sensitivity, linearity, accuracy, precision, recovery, ruggedness, and uncertainty. The robustness and efficiency of this method was proved through a successful internal RT using experienced food industry laboratories. Performance characteristics are reported for 13 certified and in-house reference materials, populating the AOAC triangle food sectors, which fulfilled AOAC criteria and recommendations for accuracy (trueness, recovery, and z-scores) and precision (repeatability and reproducibility RSD and HorRat values) regarding SLV and RT. This multielemental method is cost-efficient, time-saving, accurate, and fit-for-purpose according to ISO 17025 Norm and AOAC acceptability criteria, and is proposed as an improved version of AOAC Official Method 984.27 for fortified food products, including infant formula. PMID:19916387

  11. A comparative study of three microwave induced plasma sources for atomic emission spectrometry—I. Excitation of mercury and its determination after on-line continuous cold vapour generation

    NASA Astrophysics Data System (ADS)

    Camuña-Aguilar, J. F.; Pereiro-Garcia, R.; Sánchez-Uría, J. E.; Sanz-Medel, A.

    1994-05-01

    Argon and helium microwave induced plasmas (MIPs), sustained in a Beenakker cavity (with "capillary tube" and "tangential flow" torches), a surfatron and a microwave plasma torch (MPT) have been compared in terms of their discharge properties (plasma configuration, stability and gas consumption) and ability to excite Hg atoms. An on-line continuous mercury cold vapour generation system, using SnCl 2/ HC1 as the chemical reducing agent, was employed as the sample introduction system. Analytical figures of merit for the determination of mercury by atomic emission spectrometry (AES) showed the superiority of He discharges over the argon plasmas as excitation sources of atomic mercury. The He surfatron, with a 1 mm i.d. fused silica tube as the plasma torch, turned out to be the cavity that offered the best Hg(II) detection limit (10 pg ml -1), a linear dynamic range of more than three orders of magnitude, and a precision of ±4%. However, the plasma generated in the surfatron device used was shown to be susceptible to the entrance of molecular gases, e.g. produced during the sample reduction step, and to water vapour. Application of these systems to the sensitive determination of mercury in sea-water has been explored.

  12. 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)} \

  13. 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.

  14. Microwave Enginering Microwave Integrated Circuits

    E-print Network

    Iqbal, Sheikh Sharif

    's but are larger than MMIC's; therefore miniature hybrid circuit technology can be also called quasi;· Monolithic Microwave Integrated Circuits (MMICs): is a type of circuit in which all active and passive deposition scheme as epitaxy, ion implantation, sputtering, evaporation, diffusion. · RF/MW MMIC circuits

  15. Microwave medical devices

    Microsoft Academic Search

    F. Sterzer

    2002-01-01

    This article describes several new microwave medical devices that either were or are being developed at MMTC, Inc. in cooperation with the following institutions: Celsion Corporation, Columbia, Maryland (microwave balloon catheters); Montefiore Medical Center (MMC), Bronx, New York (microwave balloon catheters, dual microwave antennas, and microwave poration); and the University of California at San Francisco (conformal array antennas). The individuals

  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. Venus Express bistatic radar: High-elevation anomalous reflectivity

    Microsoft Academic Search

    Richard A. Simpson; G. Leonard Tyler; Bernd Häusler; Riccardo Mattei; Martin Pätzold

    2009-01-01

    Magellan (MGN) bistatic radar observations in 1994 confirmed earlier Pioneer Venus reports of unusual Venus surface reflectivity and emissivity at elevations above 6054 km radius. They also revealed that the anomalous values of surface dielectric constant $\\\\varepsilon$ near Cleopatra Patera included a large imaginary component ($\\\\varepsilon$ ? ?i 100) at 13 cm wavelength, consistent with a semiconducting surface material. The

  18. Beta function and anomalous dimensions

    SciTech Connect

    Pica, Claudio; Sannino, Francesco [CP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)

    2011-06-01

    We demonstrate that it is possible to determine the coefficients of an all-orders beta-function linear in the anomalous dimensions using as data the 2-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows us to determine the anomalous dimension of the fermion masses at the infrared fixed point, and the resulting values compare well with the lattice determinations.

  19. Microwave Ablation

    Microsoft Academic Search

    Andreas Boss; Damian Dupuy; Philippe L. Pereira

    Microwave (MW) interstitial thermoablation offers several advantages over the more commonly applied thermal ablative technique\\u000a of radiofrequency (RF) ablation for targeted tumor destruction, such as higher ablation temperature, faster treatment time,\\u000a reduced heat-sink effect, effective ablation of cystic lesions, a technologically easier multi-applicator approach, no necessity\\u000a for grounding pads, and no risk of skin burns. The technique may be used

  20. Tandem microwave waste remediation and decontamination system

    SciTech Connect

    Wicks, G.G.; Clark, D.E.; Schulz, R.L.

    1999-10-19

    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.

  1. Microwave generated plasma light source apparatus

    SciTech Connect

    Yoshizawa, K.; Ito, H.; Kodama, H.; Komura, H.; Minowa, Y.

    1985-02-05

    A microwave generated plasma light source including a microwave generator, a microwave cavity having a light reflecting member forming at least a portion of the cavity, and a member transparent to light and opaque to microwaves disposed across an opening of the cavity opposite the feeding opening through which the microwave generator is coupled. An electrodeless discharge bulb is disposed at a position in the cavity such that the cavity operates as a resonant cavity at least when the bulb is emitting light. In the bulb is encapsulated at least one discharge light emissive substance. The bulb has a shape and is sufficiently small that the bulb acts substantially as a point light source.

  2. 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.

  3. 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

  4. Signatures Of Coronal Currents In Microwave Images

    Microsoft Academic Search

    Jeongwoo Lee; Stephen M. White; N. Gopalswamy; M. R. Kundu

    1996-01-01

    . Microwave emission from solar active regions at frequencies above 4 GHz is dominated bygyroresonance opacity in strong coronal magnetic fields, which allows us to use radio observations tomeasure coronal magnetic field strengths. In this paper we demonstrate one powerful consequenceof this fact: the ability to identify coronal currents from their signatures in microwave images.Specifically, we compare potential-field (i.e., current--free)

  5. 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

  6. Estimating Microwave Delay by Atmospheric Water

    NASA Technical Reports Server (NTRS)

    Robinson, S. E.

    1986-01-01

    Tropospheric path delays for microwave very-long-baseline interferometry (VLBI) estimated with algorithm that determines and explicitly integrates simple water-vapor distribution based on temperature data from water-vapor radiometer (WVR) and emission model. Although computationally complex, method readily accommodates even dramatic changes in observation conditions, emission model, and WVR equipment. Algorithm accommodates changes in observation conditions, emission model, and radiometer hardware.

  7. Consequences of anomalous ward identities

    Microsoft Academic Search

    J. Wess; B. Zumino

    1971-01-01

    The anomalies of Ward identities are shown to satisfy consistency or integrability relations, which restrict their possible form. For the case of SU(3) × SU(3) we verify that the anomalies given by Bardeen satisfy the consistency relations. A solution of the anomalous Ward identities is also given which describes concisely all anomalous contributions to low energy theorems. The contributions to

  8. Interaction of Microwave Radiation Undergoing Stochastic Phase Jumps with Plasmas or Gases

    SciTech Connect

    Karas', V.I.; Fainberg, Ya. B.; Alisov, A.F.; Artamoshkin, A.M.; Gavrilenko, I.V.; Mirny, V.I. [National Science Center Kharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov, 61108 (Ukraine); Bingham, R. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 OQX (United Kingdom); Levchenko, V.D.; Potapenko, I.F. [Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Miusskaya pl. 4, Moscow, 125047 (Russian Federation); Lontano, M. ['Piero Caldirola' Istituto di Fisica del Plasma, Associazione Euratom-ENEA per la Fusione-CNR, Milan (Italy); Starostin, A.N. [Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow oblast, 142092 (Russian Federation)

    2005-09-15

    New types of beam-plasma devices generating intense stochastic microwave radiation in the interaction of electron beams with hybrid plasma waveguides were developed and put into operation at the National Science Center Kharkov Institute of Physics and Technology (Ukraine). The objective of the paper is to discuss the results of theoretical and experimental studies and numerical simulations of the normal and oblique incidence of linearly polarized electromagnetic waves on an interface between a vacuum and an overcritical plasma. The main results of the reported investigations are as follows: (i) for the parameter values under analysis, the transmission coefficient for microwaves with a stochastically jumping phase is one order of magnitude greater than that for a broadband regular electromagnetic wave with the same spectral density; (ii) the electrons are heated most efficiently by obliquely incident waves with a stochastically jumping phase and, in addition, the electron distribution function has a high-energy tail; and (iii) necessary conditions for gas breakdown and for the initiation of a microwave discharge in stochastic fields in a light source are determined. The anomalously large transmission coefficient for microwaves, the anomalous character of the breakdown conditions, the anomalous behavior of microwave gas discharges, and the anomalous nature of collisionless electron heating, are attributed to stochastic jumps in the phase of microwave radiation.

  9. 2622 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 46, NO. 9, SEPTEMBER 2008 WindSat Passive Microwave Polarimetric

    E-print Network

    Long, David G.

    to the physical properties of snow. For example, microwave emission is very sensitive to snow wetness; hence, Abdalati and Steffen [1] and Mote and Anderson [27] used microwave data to detect snowmelt over Greenland can change microwave emission and its frequency dependence. Abdalati and Steffen [2] and Flach et al

  10. Electron kinetics inferred from observations of microwave bursts during edge localised modes in the Mega-Amp Spherical Tokamak

    E-print Network

    Freethy, S J; Chapman, S C; Dendy, R O; Lai, W N; Pamela, S J P; Shevchenko, V F; Vann, R G L

    2014-01-01

    Recent measurements of microwave and X-ray emission during edge localised mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should be included in future models for ELMs and the ELM cycle. The observed radiative effects paradoxically imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. It is shown that this paradox can be resolved by the action of the anomalous Doppler instability which enables fast collective radiative relaxation, in the perpendicular direction, of electrons accelerated in the parallel direction by inductive electric fields generated by the initial ELM instability.

  11. Electron kinetics inferred from observations of microwave bursts during edge localized modes in the mega-amp spherical tokamak.

    PubMed

    Freethy, S J; McClements, K G; Chapman, S C; Dendy, R O; Lai, W N; Pamela, S J P; Shevchenko, V F; Vann, R G L

    2015-03-27

    Recent measurements of microwave and x-ray emission during edge localized mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should be included in future models for ELMs and the ELM cycle. The observed radiative effects paradoxically imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. It is shown that this paradox can be resolved by the action of the anomalous Doppler instability which enables fast collective radiative relaxation, in the perpendicular direction, of electrons accelerated in the parallel direction by inductive electric fields generated by the initial ELM instability. PMID:25860751

  12. Microwave Engineering Problems in the Microwave Oven

    Microsoft Academic Search

    John M. Osepchuk

    1976-01-01

    A general review of microwave engineering problems of the microwave oven is presented. Of central importance is the continuing improvement of the microwave magnetron in efficiency and stability. The goal of uniform heating is discussed with reference to measurement techniques and efforts at standardization. Advances in door-seal techniques are presented with reference to leakage and RFI requirements. Lastly the relevance

  13. 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.

  14. 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...

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

    Microsoft Academic Search

    Luis Gras; Juan Mora; José L. Todol??; Antonio Canals; Vicente Hernandis

    1999-01-01

    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

  16. The microwave technology

    Microsoft Academic Search

    Joseph Z Bih

    2003-01-01

    The nature of microwave technology is defined in the discovery of microwave, which was initially used for military purposes. The invention of radar and microwave ovens are both attributed to this significant discovery. This paper explores significant applications of microwave technology and analyzed the impact on various aspects of this high technology. The new paradigm shift has resulted in tremendous

  17. Validation of UARS Microwave Limb Sounder ozone measurements

    Microsoft Academic Search

    L. Froidevaux; W. G. Read; T. A. Lungu; R. E. Cofield; E. F. Fishbein; D. A. Flower; R. F. Jarnot; B. P. Ridenoure; Z. Shippony; J. W. Waters; J. J. Margitan; I. S. McDermid; R. A. Stachnik; G. E. Peckham; G. Braathen; T. Deshler; J. Fishman; D. J. Hofmann; S. J. Oltmans

    1996-01-01

    This paper describes the validation of ozone data from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS). The MLS ozone retrievals are obtained from the calibrated microwave radiances (emission spectra) in two separate bands, at frequencies near 205 and 183 GHz. Analyses described here focus on the MLS Version 3 data (the first set of files made publicly

  18. Software for Early Cancer Detection Using Microwave Breast Images

    Microsoft Academic Search

    M. Costin; O. Baltag; S. Bejinariu

    2008-01-01

    Microwave detection of the abnormally developing tissue structure is a new noninvasive technique, using human body emission radiometry. The research is discussing practical aspects of implementing this type of early breast cancer detection. A special software have been implemented in order to map the measured values and to constitute a microwave image data base. The patient anamnesis is stored together

  19. Resistively detected microwave absorption by planar spin oscillators

    Microsoft Academic Search

    A. Nogaret; N. J. Lambert; Y. Krupko; J. C. Portal; H. E. Beere; D. A. Ritchie

    2006-01-01

    We report on a novel class of RF spintronics devices directed towards making nanoscale microwave sources. Microwave emission is produced by a process of spin resonance that occurs in hybrid semiconductor-ferromagnetic nanostructures when a two-dimensional electron gas is subjected to both a magnetic field gradient and a constant magnetic field applied at right angles of each other. Current injection activates

  20. New microwave concepts based on carbon nano tubes

    Microsoft Academic Search

    H. L. Hartangel

    2008-01-01

    The paper discusses microwave-device concepts based on carbon nanotubes. First, the physical properties of the carbon nanotubes are briefly described. Then, field emission devices, quantum electronic devices, microwave passive and active devices all based on carbon nanotubes are in detail described and their performance evaluated.

  1. 3350 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 49, NO. 9, SEPTEMBER 2011 Lunar Microwave Brightness Temperature: Model

    E-print Network

    Marzano, Frank Silvio

    , Moon exploration, Moon microwave emission, neural network (NN), radiative transfer (RT) model. I Microwave Brightness Temperature: Model Interpretation and Inversion of Spaceborne Multifrequency, ice, and regolith, the probability of detection of the presence of discontinuities beneath the lunar

  2. Application of microwave imaging system for density fluctuation measurements on Large Helical Device

    E-print Network

    Paris-Sud XI, Université de

    and vertically (poloidally) extended emissions in ECEI system and since both systems operate in a close microwave of the detection system to form an image. The presented work emphasizes the developing of the microwave imagingApplication of microwave imaging system for density fluctuation measurements on Large Helical

  3. HARD X-RAY AND MICROWAVE OBSERVATIONS OF MICROFLARES Jiong Qiu,1, 2

    E-print Network

    Qiu, Jiong

    into the OVSA observing window, about 40% are detected in microwaves. Using these hundreds of events as samplesV and microwave emission at around 10 GHz. Spectral analysis in these two wavelengths corroborates the nonthermalHARD X-RAY AND MICROWAVE OBSERVATIONS OF MICROFLARES Jiong Qiu,1, 2 Chang Liu,2 Dale E. Gary,2 Gelu

  4. 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.

  5. 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.

  6. 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

  7. Determination of butyl- and phenyltin compounds in human urine by HS-SPME after derivatization with tetraethylborate and subsequent determination by capillary GC with microwave-induced plasma atomic emission and mass spectrometric detection.

    PubMed

    Zachariadis, G A; Rosenberg, E

    2009-04-30

    A headspace solid-phase micro-extraction (HS-SPME) method was developed and optimized for gas chromatographic separation and determination of commonly found organotin compounds in human urine after potential exposure. Butyl- and phenyltin compounds were in situ derivatized to ethylated derivatives by sodium tetraethylborate (NaBEt(4)) directly in the urine matrix. The relevant parameters affecting the yield of the SPME procedure were examined using tetrabutyltin as internal standard. The method was optimized for direct use in the analysis of undiluted human urine samples and mono-, di- and tri-substituted butyl- and phenyltin compounds could be determined after a 15-min headspace extraction time at room temperature. The selectivity of the microwave-induced plasma atomic emission detector (MIP-AED) as an element specific detector in combination with the relatively selective sample preparation technique of HS-SPME allowed the interference-free detection of the organotin compounds in all cases. A quadrupole mass spectrometer was used in parallel experiments as a detector for the confirmation of the identity molecular structure of the eluted compounds. The performance characteristics of the developed method are given for the determination of mixtures of these compounds. Finally the proposed method was applied to the analysis of several human urine samples. PMID:19203626

  8. 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.

  9. Is Bacteriophage Adsorption Anomalous?

    NASA Astrophysics Data System (ADS)

    Moldovan, Radu; Wu, X. L.

    2004-03-01

    The study of infection process of bacteria by phages has a long history. One of the paradoxes is that the rate of binding of phage particles to their host is higher than the theoretical limit, k=4paD, assuming that the bacterium is an ideal sink. Here a is the size of the bacterium and D is the diffusion coefficient of the phage. Various explanations were provided in the past to account for the anomalous adsorption, such as bacterial swimming and special roles of appendages on a phage for enhanced binding. Using a common strain E. coli. (YMEL), we investigated phage adsorption and DNA translocation kinetics using a standard tittering technique. We found that phage adsorption depends strongly on the divalent salt (MgSO4) concentration and the adsorption rate can change by orders of magnitude. Even in the strongest adsorption regime, with Mg++=10-2 M, the adsorption coefficient is about 10 times smaller than the theoretical limit, suggesting that the average number of phage receptors on a bacterium is about 50 or so. We also derived a set of rate equations taking into account phage desorption and DNA translocation rates. Surprisingly this set of simple equations explains our experimental data extremely well. Under certain conditions the DNA translocation appears to be "frozen", with a nearly zero translocation rate. Such a condition makes it possible to control and initiate the DNA translocation process.

  10. 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.

  11. Investigation of anomalous penetration

    NASA Astrophysics Data System (ADS)

    Young, Robert D.; Littlefield, David L.; Horie, Y.

    1994-07-01

    Numerical experiments were performed as part of an ongoing effort to understand the Russian claims of anomalous or super-deep penetration. The claim is that unusually large penetration to particle diameter ratios are obtained for a few particles when a large number of particles bombard a solid target. As a first step in this process, cumulation effects were examined to determine their potential mechanistic role in the interaction. Two-dimensional hydrocode analyses were used to simulate simultaneous particle impact into a semi-infinite target. As a consequence of the chosen axisymmetric model, impacting particle were rings, collapsing to a single sphere when the modeled particles were centered on the axis of symmetry. Results of the analysis indicate that when the distance between particle centers is nonzero, cylindrical shock waves form which have propagation components both coverging to an diverging from the axis of symmetry. Energy density cumulation results due to the decreasing volume of converging shock waves approaching the symmetry axis. Numerical results show a four fold increase in shock wave amplitude at the time of convergence with respect to the shock amplitude produced at impact. Surprisingly, the amplitude at the time of the converged shock is only a weak function of the particle distance from the symmetry axis. As a result of the convergence, a tunnel forms along the axis of symmetry which, upon release, changes phase to liquid and vapor which possesses high velocity components. This phenomenon was observed at impact velocities as low as 3 km/s.

  12. 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.

  13. Wave-particle interaction and peculiarities of propagation and emission of accelerated particles in solar flares

    NASA Astrophysics Data System (ADS)

    Stepanov, A. V.; Tsap, Yu. T.

    2006-08-01

    Consequences of wave-particle interaction in the propagation and emission of accelerated particles in solar flares are considered. i. Strong diffusion energetic particles on small-scale waves (Trakhtengerts 1984) gives time delays of gamma ray line emission vs hard X-ray emission when electron and protons are accelerated simultaneously. ii. Anomalous propagation of relativistic electrons along the flare loop with velocity of 30 times less compared with light velocity (Yokoyama et al 2002) is explained in terms of the collective effects of interaction of electrons with plasma turbulence. A cloud of high-energetic electrons responsible for microwave emission generates whistler waves and a turbulent "wall" in the loop is formed. The electrons undergo strong resonant scattering and the emission front propagates with the wave phase velocity, which is much lower than particle velocity. iii. Absence of linear polarization (? 0.07%) in H? emission of some flares (Bianda et al 2005) is interpreted in terms of pitch-angle scattering of proton beams on small-scale Alfven waves. References Bianda M., Benz F.O., Stenflo J.O. et al 2005, A&A, 434, 1183 Trakhtengerts V.Yu. 1984, Relaxation of Plasma with Anisotropic Velocity Distribution, in A.A.Galeev and R.N.Sudan (eds.) Basic Plasma Physics II, North-Holland Physics Publishing Yokoyama T., Nakajima H., Shibasaki K, et al. 2002, ApJ, 576, L87

  14. Ultra-violet and resonant laser ablation coupled with microwave induced plasma atomic emission spectrometry and determination of tin in nickel based alloys by electrothermal atomizer atomic absorption and laser excited atomic fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Yang, Xiaodong

    Chapter 1 reviews laser ablation in analytical atomic spectrometry. Laser ablation is categorized into two functions: one is used as a sample introduction method, the other function is used as a microprobe analysis method. Both fundamental and applicational aspects are reviewed with the citations of related papers. This chapter also serves as an introduction to the work which is described in chapter 2 and chapter 3 as laser ablation is a relatively new research area for the research group. In chapter 2, instrumentation for excimer (308nm) laser ablation of samples was coupled with a microwave induced plasma (MLP), and evaluated for its potential as an approach to solid sampling for atomic emission spectrometry. Operating parameters were optimized, and the effects of laser repetition rate and number of laser shots on the emission signal were investigated. The UV excimer laser removed more material than would be expected of an infrared laser of similar energy. The chromium detection limit in the solid steel sample was estimated to be about 500 mug/g. In chapter 3, a wavelength tunable optical parametric oscillator (OPO) laser was used to ablate a steel sample into the same apparatus described in chapter 2. The emission signal for the elements was selectively enhanced when the ablation wavelength was tuned to be in resonance with any atomic transition of that element. This was the first report of the observation of resonant ablation by use of optical detection, as prior reports of resonant ablation have used mass spectrometric detectors. Chapter 4 reviews the publications in laser excited atomic fluorescence spectrometry in recent eight years. The focus of the review is on recent development on new instruments and applications of this technique. Chapter 5 studies the determination of tin in nickel-based alloys with laser excited atomic fluorescence in a graphite furnace. Zeeman electrothermal atomizer atomic absorption spectrometry and inductively coupled plasma mass spectrometry methods were also used. The laser excited atomic fluorescence method turned out to be as accurate as the other techniques. The atomic fluorescence method was simple to develop and did not need a sophisticated background correction technique to do the analyses.

  15. Radio and XRay Emission from MainSequence K Stars

    E-print Network

    Guedel, Manuel

    on strong X­rays, rapid rotation, or strong Ca II emission lines. Seven targets were detected steady sources of strong microwave emission at times when no flaring activity is evident (Gary & Linsky). Several surveys suggested that at spectral types earlier than M0 microwave emission is considerably weaker

  16. 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.

  17. Microwaves for immunohistochemistry.

    PubMed

    Boon, M E; Kok, L P

    1994-01-01

    Microwaves are now widely used in immunohistochemistry for fixing and stabilizing tissue prior to embedding and cutting, for antigen retrieval and for immunoincubations. These techniques can be used for frozen sections and for material embedded in paraffin and plastic. Material prepared in this way shows high contrast in light microscopy. In principle, these microwave methods can also be used for electron microscopy. To be successful in the application of these techniques, insight into the physics of exposure to microwaves and the effects of microwaves on the material is a must. Microwave immunohistochemistry depends on optimal temperature control. To guarantee this, special measures should be taken and dedicated laboratory ovens should be used. The recently developed Coverplate units facilitate immunoincubations in the microwave oven. We show that the total microwave approach, combining microwave fixation, embedding and immunoincubations, is very useful for confocal microscopy. PMID:8055246

  18. Microwave heating of foodstuffs

    Microsoft Academic Search

    M. E. C. Oliveira; A. S. Franca

    2002-01-01

    The temperature distribution in a product submitted to microwave radiation is governed by the interaction and absorption of radiation by the medium and the accompanying transport processes due to the dissipation of electromagnetic energy into heat. Thus, modeling of microwave heating involves coupling the models for microwave power absorption and temperature distribution inside the product. In this study, a model

  19. Dual microwave andoptical oscillator

    Microsoft Academic Search

    X. Steve Yao; Lute Maleki

    1997-01-01

    We describe and demonstrate a novel device in which a microwave oscillation and an optical oscillation are generated and directly coupled with each other. With the mutual inf luence between the microwave and the optical oscillations, we project that this device is capable of simultaneously generating stable optical pulses down to the subpicosecond level and spectrally pure microwave signals at

  20. Microwave holographic interferometry

    Microsoft Academic Search

    G. Papi; V. Russo; S. Sottini

    1971-01-01

    Microwave holography is an extension of the optical holography to the microwave field. In fact, by using a well-known characteristic of the holographic process, it is possible to record the hologram at frequencies very far from the optical region (microwave) and to reconstruct a visible image by laser light. This paper describes the experimental apparatus and the technique used for

  1. Is anomalous transport diffusive

    SciTech Connect

    Rewoldt, G.

    1989-09-01

    It has often been assumed that the anomalous transport from saturated plasma instabilities is diffusive'' in the sense that the particle flux, {Gamma}, the electron energy flux, q{sub e}, and the ion energy flux, q{sub i}, can be written in forms that are linear in the density gradient, dn/dr, the electron temperature gradient, dT{sub e}/dr, and the ion temperature gradient dT{sub i}/dr. In the simplest form, {Gamma} = {minus} D{sub n}{sup n}(dn/dr), q{sub e} = {minus} D{sub e}{sup e}n(dT{sub e}/dr), and q{sub i} = {minus}D{sub i}{sup i}n(dT{sub i}/dr). A possible generalization of this is to include so-called off-diagonal'' terms, with {Gamma} = nV{sub n} {minus} D{sub n}{sup n}(dn/dr) {minus} D{sub n}{sup e}(n/T{sub e})(dT{sub e}/dr) {minus} D{sub n}{sup i}(n/T{sub i})(dT{sub i}/dr), with corresponding forms for the energy fluxes. Here, general results for the quasilinear particle and energy fluxes, resulting from tokamak linear microinstabilities, are evaluated to assess the relative importance of the diagonal and the off-diagonal terms. A further possible generatlization is to include also contributions to the fluxes from higher powers of the gradients, specifically quadratic'' contributions proportional to (dn/dr){sup 2}, (dn/dr)(dT{sub e}/dr), and so on. A procedure is described for evaluating the corresponding coefficients, and results are presented for illustrative realistic tokamak cases. Qualitatively, it is found that the off-diagonal diffusion coefficients can be as big as the diagonal ones, and that the quadratic terms can be larger than the linear ones. The results thus strongly suggest that the commonly used diffusive'' approximation with only diagonal terms, {Gamma} = {minus}D{sub n}{sup n}(dn/dr), and correspondingly for the energy fluxes, is not adequate in practice. 9 refs., 1 tabs.

  2. JOURNAL DE PHYSIQUE CoIIoque C6, suppliment au no 12, Tome 37, Dkcembre 1976, page C6-473 ANOMALOUS SPIN STATES OF IRON (11) IN MOSSBAUER EMISSION

    E-print Network

    Boyer, Edmond

    etudie les spectres d'emission Mossbauer de complexes [57Co(phen)~(NCS)~]et [57Co(bpy)~(NCS)2],observe spectra of the complexes [57Co(phen)~(NCS)z](phen = 1.10-phenanthroline)and [57Co(bpy)2(NCS)~](bpy= a, a

  3. 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.

  4. arXiv:0807.3985v1[astro-ph]25Jul2008 Draft version January 21, 2010

    E-print Network

    White, Glenn J.

    - 60 GHz. The anomalous microwave emission was first detected at 14 and 32 GHz by Leitch et al. (1997 style emulateapj v. 11/12/01 ANOMALOUS MICROWAVE EMISSION FROM THE Hii REGION RCW175 C. Dickinson,1 R. D for anomalous microwave emission in the RCW175 Hii region. Motivated by 33 GHz 13 resolution data from the Very

  5. Anomalous relaxation in fractal structures

    SciTech Connect

    Fujiwara, S.; Yonezawa, F. (Department of Physics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223 (Japan))

    1995-03-01

    For the purpose of studying some interesting properties of anomalous relaxation in fractal structures, we carry out Monte Carlo simulations of random walks on two-dimensional fractal structures (Sierpinski carpets with different cutouts and site-percolation clusters in a square lattice at the critical concentration). We find that the relaxation is of the Cole-Cole type [J. Chem. Phys. 9, 341 (1941)], which is one of the empirical laws of anomalous relaxation. Scaling properties are found in the relaxation function as well as in the particle density. We also find that, in strucures with almost the same fractal dimension, relaxation in structures with dead ends is slower than that in structures without them. This paper ascertains that the essential aspects of the anomalous relaxation due to many-body effects can be explained in the framework of the one-body model.

  6. Anomalous Earth flybys of spacecraft

    NASA Astrophysics Data System (ADS)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2015-07-01

    A small deviation from the potential is expected for the gravitational interaction of extended bodies. It is explained as a consequence of a recently proposed gravitational impact model (Wilhelm et al. in Astrophys. Space Sci. 343:135-144, 2013) and has been applied to anomalous perihelion advances by Wilhelm and Dwivedi (New Astron. 31:51-55, 2014). The effect—an offset of the effective gravitational centre from the geometric centre of a spherical symmetric body—might also be responsible for the observed anomalous orbital energy gains and speed increases during Earth flybys of several spacecraft. However, close flybys would require detailed considerations of the orbit geometry. In this study, an attempt is made to explain the anomalous Earth flybys of the Galileo, NEAR Shoemaker and Rosetta spacecraft.

  7. Effect of different glycation agents on Cu(II) binding to human serum albumin, studied by liquid chromatography, nitrogen microwave-plasma atomic-emission spectrometry, inductively-coupled-plasma mass spectrometry, and high-resolution molecular-mass spectrometry.

    PubMed

    Corrales Escobosa, Alma Rosa; Wrobel, Katarzyna; Yanez Barrientos, Eunice; Jaramillo Ortiz, Sarahi; Ramirez Segovia, Alejandra Sarahi; Wrobel, Kazimierz

    2015-02-01

    The ability of human serum albumin to capture unbound copper under different clinical conditions is an important variable potentially affecting homeostasis of this element. Here, we propose a simple procedure based on size-exclusion chromatography with on-line UV and nitrogen microwave-plasma atomic-emission spectrometry (MP-AES) for quantitative evaluation of Cu(II) binding to HSA upon its glycation in vitro. The Cu-to-protein molar ratio for non-glycated albumin was 0.98?±?0.09; for HSA modified with glyoxal (GO), methylglyoxal (MGO), oxoacetic acid (GA), and glucose (Glc), the ratios were 1.30?±?0.22, 0.72?±?0.14, 0.50?±?0.06, and 0.95?±?0.12, respectively. The results were confirmed by using ICP-MS as an alternative detection system. A reduced ability of glycated protein to coordinate Cu(II) was associated with alteration of the N-terminal metal-binding site during incubation with MGO and GA. In contrast, glycation with GO seemed to generate new binding sites as a result of tertiary structural changes in HSA. Capillary reversed-phase liquid chromatography with electrospray-ionization quadrupole-time-of-flight tandem mass spectrometry enabled detection and identification of Cu(II) coordinated to the N-terminal metal-binding site (Cu(II)-DAHK) in all tryptic digests analyzed. This is the first report confirming Cu(II)-DAHK species in HSA by means of high-resolution tandem mass spectrometry, and the first report on the use of MP-AES in combination with chromatographic separation. PMID:25428457

  8. AnomalousAnomalous AharonovBohmAharonovBohm gapgap

    E-print Network

    Marini, Andrea

    currents #12;The AB effect in carbon nano-tubes (CNTs) A. Bachtold et al., Nature 397, 673 (1999) S. Zaric is increased... ...consistently with a gap flux dependence #12;The AB effect in carbon nano-tubes (CNTs) AAnomalousAnomalous Aharonov­BohmAharonov­Bohm gapgap oscillations inoscillations in carbon

  9. Microwave sintering of nanopowder ZnNb2O6: Densification, microstructure and microwave dielectric properties

    NASA Astrophysics Data System (ADS)

    Bafrooei, H. Barzegar; Nassaj, E. Taheri; Hu, C. F.; Huang, Q.; Ebadzadeh, T.

    2014-12-01

    High density ZnNb2O6 ceramics were successfully fabricated by microwave sintering of ZnO-Nb2O5 and ZnNb2O6 nanopowders. Phase formation, microstructure and microwave electrical properties of the microwave sintered (MS) and microwave reaction sintered (MRS) specimens were examined using X-ray diffraction, field emission scanning electron microscopy and microwave dielectric properties measurement. Specimens were sintered in a temperature range from 950 to 1075 °C for 30 min at an interval of 25 °C using a microwave furnace operated at 2.45 GHz frequency, 3 kW power. XRD pattern revealed the formation of pure columbite phase of ZnNb2O6. The SEM micrographs show grain growth and reduction in porosity of specimens with the increase in sintering temperature. Good combination of microwave dielectric properties (?r~23.6, Qf~64,300 GHz and ?f~-66 ppm/°C and ?r~24, Qf~75,800 GHz and ?f~-64 ppm/°C) was obtained for MS- and MRS-prepared samples at 1000 °C and 1050 °C for 30 min, respectively.

  10. Microwave heating apparatus and method

    SciTech Connect

    Johnson, A.J.; Peterson, R.D.; Swanson, S.D.

    1990-07-10

    This patent describes a microwave apparatus for heating materials. It comprises: a microwave energy input for delivering microwave energy, a resonant cavity for receiving microwave energy through the input, a microwave energy choke encompassing the floor opening of the resonant cavity, a microwave energy reflective container for holding the materials to be heated, turning the container during exposure of the materials in the container to microwave energy, located outside of the cavity, and means for lifting the container, located outside of the cavity.

  11. Anomalous Video Event Detection Using Spatiotemporal Context

    E-print Network

    Tsaftaris, Sotirios

    . Keywords: Video surveillance, anomaly detection, data mining, clustering, context 1. Introduction DiscoveryAnomalous Video Event Detection Using Spatiotemporal Context Fan Jianga, , Junsong Yuanc , Sotirios anomalous video event detection approaches that ana- lyze object trajectories only, we propose a context

  12. 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.

  13. Continuous Microwave Excitation of Excimer Lamps.

    NASA Astrophysics Data System (ADS)

    Hassal, Scott Bradley

    1991-01-01

    For decades, microwaves have been used to create gas discharges for many applications. This thesis deals with the use of microwaves to excite gas discharges for incoherent optical sources, with particular emphasis on excimer systems. In addition, microwave excitation of a gas laser is considered. A novel apparatus was designed and built to couple 2.45-GHz microwave radiation into a gas discharge. The microwave resonator is the essential part of this equipment, and a detailed discussion of its design and performance is given. The resonator is characterized both theoretically and experimentally in order to determine the coupling efficiency and peak electric-field strength. Specialized theory is developed in order to evaluate many parameters of a microwave-excited discharge. The phenomenon of skin effect is investigated quantitatively and expressions for the plasma frequency and electron density are developed in terms of collision frequency and observable parameters (e.g., skin depth). Expressions for peak electric-field strength, ionization coefficient and collisionless electron energy are also developed. The results of an extensive investigation of continuous-wave microwave-excited excimer fluorescence are reported. Rare-gas halide, homonuclear halogen and heteronuclear halogen systems are examined and the corresponding ultraviolet spectra are presented. Truly continuous excimer emission has been achieved (for the first time) on several transitions. For systems of particular interest (e.g. XeCl and KrCl), the effects of total pressures and gas composition on fluorescence output are investigated, and the appropriate spectra are presented. Finally, the potential operation of microwave-excited carbon dioxide and argon-ion gas lasers is investigated, and upper limits are deduced for the small-signal gain under various conditions.

  14. 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.

  15. 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 background. Fluctuations in the Cosmic Microwave Background MWMW 370 km/s #12;Microwave Background Features

  16. 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.

  17. Microwave properties and systems overview

    NASA Astrophysics Data System (ADS)

    Lawrence, Ronald

    1993-06-01

    Of particular significance to the operational success of a missile using microwave communications is the interference introduced by the rocket exhaust plume. As a hot and turbulent gas stream the exhaust has electrical properties that can seriously degrade guidance and tracking. Also present is the potential for missile detection offered by energy scattered from microwave signals impinging upon the plume to present a radar cross section, and an exhaust signature from inherent emission sources within the plume. This paper presented in AGARD Lecture Series 188, follows from AGARD Advisory Report 287 submitted by Propulsion and Energetics Panel Working Group 21 entitled 'Terminology and Assessment Methods of Solid Propellant Rocket Exhaust Signatures.' It provides a description of microwave propagation through a rocket exhaust, the cause of signal attenuation, and the generation of phase and amplitude sideband noise. Consideration is given to the effects of missile flight velocity and altitude. Diffraction and refraction processes are discussed, particularly in relation to plumes containing high density concentrations of free electrons. Radiation sources, mainly at millimetric wavelengths, are included together with signature implications. The effects of exhaust interference with communications is examined from a system point of view and some methods of relief from the interference are considered.

  18. Infrared-correlated 31-GHz radio emission from Orion East

    NASA Astrophysics Data System (ADS)

    Dickinson, C.; Casassus, S.; Davies, R. D.; Allison, J. R.; Bustos, R.; Cleary, K.; Davis, R. J.; Jones, M. E.; Pearson, T. J.; Readhead, A. C. S.; Reeves, R.; Taylor, A. C.; Tibbs, C. T.; Watson, R. A.

    2010-10-01

    Lynds dark cloud LDN1622 represents one of the best examples of anomalous dust emission, possibly originating from small spinning dust grains. We present Cosmic Background Imager (CBI) 31-GHz data of LDN1621, a diffuse dark cloud to the north of LDN1622 in a region known as Orion East. A broken ring-like structure with diameter ~20 arcmin of diffuse emission is detected at 31 GHz, at ~20-30 mJy beam-1 with an angular resolution of ~5 arcmin. The ring-like structure is highly correlated with far-infrared (FIR) emission at 12-100?m with correlation coefficients of r ~ 0.7-0.8, significant at ~10?. The FIR-correlated emission at 31 GHz therefore appears to be mostly due to radiation associated with dust. Multifrequency data are used to place constraints on other components of emission that could be contributing to the 31-GHz flux. An analysis of the GB6 survey maps at 4.85 GHz yields a 3? upper limit on free-free emission of 7.2 mJy beam-1 (<~30 per cent of the observed flux) at the CBI resolution. The bulk of the 31-GHz flux therefore appears to be mostly due to dust radiation. Aperture photometry, at an angular resolution of 13 arcmin and with an aperture of diameter 30 arcmin, allowed the use of IRAS maps and the Wilkinson Microwave Anisotropy Probe 5-yr W-band map at 93.5 GHz. A single modified blackbody model was fitted to the data to estimate the contribution from thermal dust, which amounts to ~10 per cent at 31 GHz. In this model, an excess of 1.52 +/- 0.66 Jy (2.3?) is seen at 31 GHz. Correlations with the IRAS 100?m gave a coupling coefficient of 18.1 +/- 4.4?K (MJy sr-1)-1, consistent with the values found for LDN1622.

  19. Does The Pioneer Anomalous Acceleration Really Exist?

    E-print Network

    Walter Petry

    2005-09-21

    The analysis of the Pioneer 10 and 11 data demonstrated the presence of an anomalous Doppler frequency blue-shift drift which is interpreted as an anomalous acceleration. The Doppler frequency dirft follows by considering the motions of the Pioneers in the universe, i.e. it is of cosmological origin. There is no anomalous acceleration.

  20. Anomalous diffusion: A dynamic perspective

    Microsoft Academic Search

    R. Muralidhar; D. Ramkrishna; H. Nakanishi; D. Jacobs

    1990-01-01

    This paper investigates whether spontaneous, stationary velocity fluctuations can lead to deviations from the regular Fickian diffusion. A kinematic analysis reveals that anomalous diffusion, both fast and slow, arises from long-tailed velocity auto-correlation functions (VACF). This infinite span of interdependence of the random velocity leads to the breakdown of the central limit theorem for particle displacements. A generalized Langevin equation,

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  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. Ignition characteristics of methane/air premixed mixture by microwave-enhanced laser-induced breakdown plasma.

    PubMed

    Nishiyama, Atsushi; Moon, Ahsa; Ikeda, Yuji; Hayashi, Jun; Akamatsu, Fumiteru

    2013-11-01

    A microwave-enhanced plasma generation technique was combined with laser-induced ignition to improve ignition characteristics. A locally intensified microwave field was formed near the laser-induced breakdown plasma. As the plasma absorbed the microwaves, the plasma emission intensity increased. The plasma lifetime could be controlled by changing the microwave oscillation duration. Furthermore, the microwave-enhanced laser-induced breakdown plasma improved the minimum ignition energy of the methane/air pre-mixture with just a small amount of absorbed microwave energy. PMID:24514928

  9. 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.

  10. Anomalous transport induced by sheath instability in Hall effect thrusters

    SciTech Connect

    Taccogna, Francesco [Istituto di Metodologie Inorganiche e dei Plasmi-CNR, via Amendola 122/D, 70126 Bari (Italy); Longo, Savino; Capitelli, Mario [Istituto di Metodologie Inorganiche e dei Plasmi-CNR, via Amendola 122/D, 70126 Bari (Italy); Dipartimento di Chimica, Universita degli Studi di Bari, via Orabona 4, 70120 Bari (Italy); Schneider, Ralf [Max Planck Institute fuer Plasmaphysik, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)

    2009-06-22

    It is well recognized to ascribe the anomalous cross-field conductivity inside Hall-effect thrusters to fluctuation-induced transport due to gradient-driven instabilities (Rayleigh or electron drift) and to electron-wall interaction (near-wall conductivity). In this letter, we have performed numerical experiments showing the possibility of another mechanism inducing azimuthal fluctuations: the lateral sheath instability. It is created by a negative differential resistance of the current-voltage I-V characteristic of the floating wall as a consequence of high secondary electron emission. The contribution from this effect to the anomalous axial current is calculated and it accounts of more than 80% of the experimental value.

  11. Optical emission spectrometric determination of arsenic and antimony by continuous flow chemical hydride generation and a miniaturized microwave microstrip argon plasma operated inside a capillary channel in a sapphire wafer

    NASA Astrophysics Data System (ADS)

    Pohl, Pawel; Zapata, Israel Jimenéz; Bings, Nicolas H.; Voges, Edgar; Broekaert, José A. C.

    2007-05-01

    Continuous flow chemical hydride generation coupled directly to a 40 W, atmospheric pressure, 2.45 GHz microwave microstrip Ar plasma operated inside a capillary channel in a sapphire wafer has been optimized for the emission spectrometric determination of As and Sb. The effect of the NaBH 4 concentration, the concentration of HCl, HNO 3 and H 2SO 4 used for sample acidification, the Ar flow rate, the reagent flow rates, the liquid volume in the separator as well as the presence of interfering metals such as Fe, Cu, Ni, Co, Zn, Cd, Mn, Pb and Cr, was investigated in detail. A considerable influence of Fe(III) (enhancement of up to 50 %) for As(V) and of Fe(III), Cu(II) and Cr(III) (suppression of up to 75%) as well as of Cd(II) and Mn(II) (suppression by up to 25%) for Sb(III) was found to occur, which did not change by more than a factor of 2 in the concentration range of 2-20 ?g ml - 1 . The microstrip plasma tolerated the introduction of 4.2 ml min - 1 of H 2 in the Ar working gas, which corresponded to an H 2/Ar ratio of 28%. Under these conditions, the excitation temperature as measured with Ar atom lines and the electron number density as determined from the Stark broadening of the H ? line was of the order of 5500 K and 1.50 · 10 14 cm - 3 , respectively. Detection limits (3?) of 18 ng ml - 1 for As and 31 ng ml - 1 for Sb were found and the calibration curves were linear over 2 orders of magnitude. With the procedure developed As and Sb could be determined at the 45 and 6.4 ?g ml - 1 level in a galvanic bath solution containing 2.5% of NiSO 4. Additionally, As was determined in a coal fly ash reference material (NIST SRM 1633a) with a certified concentration of As of 145 ± 15 ?g g - 1 and a value of 144 ± 4 ?g g - 1 was found.

  12. Compact 2.45 GHz microwave ion/atom source

    SciTech Connect

    Sakamoto, Y.; Kasuya, T.; Wada, M.; Maeno, S. [Graduate School of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan); Novelion Systems, Co., Ltd, Kyotanabe, Kyoto 610-0332 (Japan)

    2008-02-15

    Characteristics of a microwave driven 3.4 cm diameter compact ion/atom source equipped with permanent magnets were tested. The source can be mounted to a standard copper gasket flange, and microwave power is supplied through an N-type microwave connector. The ion source plasma was observed through an ion extraction hole with an optical emission spectrometer. Peak height of an optical line spectrum emission corresponding to atomic nitrogen increased in proportion to the microwave input power. Quadrupole mass spectrometer showed that N{sup +} and N{sub 2}{sup +} were the dominant species in the extracted ion beam. Nitrogen ion current density of 0.23 mA/cm{sup 2} was obtained with only 10 W discharge power and 6x10{sup -3} Pa source surrounding pressure.

  13. Compact 2.45GHz microwave ion/atom sourcea)

    NASA Astrophysics Data System (ADS)

    Sakamoto, Y.; Kasuya, T.; Wada, M.; Maeno, S.

    2008-02-01

    Characteristics of a microwave driven 3.4cm diameter compact ion/atom source equipped with permanent magnets were tested. The source can be mounted to a standard copper gasket flange, and microwave power is supplied through an N-type microwave connector. The ion source plasma was observed through an ion extraction hole with an optical emission spectrometer. Peak height of an optical line spectrum emission corresponding to atomic nitrogen increased in proportion to the microwave input power. Quadrupole mass spectrometer showed that N+ and N2+ were the dominant species in the extracted ion beam. Nitrogen ion current density of 0.23mA/cm2 was obtained with only 10W discharge power and 6×10-3Pa source surrounding pressure.

  14. Microwaves dry fine coal

    SciTech Connect

    Chironis, N.P.

    1986-12-01

    Tests by the Bureau of Mines' Twin Research Center at Minneapolis, Minn., has shown that drying fine coal in the minus 1/4-in. range with microwave energy is not only feasible but also very efficient. The microwave technique, uses a custom-designed conveyorized microwave oven to dry three coal types: bituminous, subbituminous and lignite. Remarkable drying efficiencies of 97% for Colowyo coal of minus 1/4-in. plus 28 mesh, as well as for Illinois No. 6 coal of minus 28 mesh plus 100 mesh were obtained by the bureau using the pilot-scale continuous drying microwave system.

  15. Artificial color perception using microwaves

    E-print Network

    Choudhury, Debesh

    2013-01-01

    We report the feasibility of artificial color perception under microwave illumination using a standard microwave source and an antenna. We have sensed transmitted microwave power through color objects and have distinguished the colors by analyzing the sensed transmitted power. Experiments are carried out using a Gunn diode as the microwave source, some colored liquids as the objects and a microwave diode as the detector. Results are presented which open up an unusual but new way of perceiving colors using microwaves.

  16. Partial anomalous pulmonary venous return.

    PubMed

    Broy, Charles; Bennett, Steven

    2008-06-01

    Partial anomalous pulmonary venous return (PAPVR) is an uncommon congenital abnormality that occurs in 0.4 to 0.7% of postmortem examinations. Ninety percent of these anomalies are associated with an atrial septal defect. Partial anomalous pulmonary venous return occurs more commonly on the right than the left and is manifested by abnormal return of the pulmonary veins to the central venous circulation. Most patients are asymptomatic, but when symptoms are present they are due to shunting of oxygenated blood to the venous circulation. We submit the case of a recently activated solider who presented with dyspnea on exertion refractory to inhaled corticosteroids and an 8.5-mm solitary pulmonary nodule. Further diagnostic imaging revealed PAPVR. Our case appears to be the first report of a solitary pulmonary nodule as the initial presentation of a right upper lobe PAPVR with return to the superior vena cava in the absence of associated atrial septal defect. PMID:18595412

  17. On the mechanism of electromagnetic microwave absorption in superfluid helium

    SciTech Connect

    Pashitskii, E. A., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

    2012-08-15

    In experiments on electromagnetic (EM) wave absorption in the microwave range in superfluid (SF) helium [1-3], a narrow EM field absorption line with a width on the order of (20-200) kHz was observed against the background of a wide absorption band with a width of 30-40 GHz at frequencies f{sub 0} Almost-Equal-To 110-180 GHz corresponding to the roton gap energy {Delta}{sub r}(T) in the temperature range 1.4-2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms ({sup 4}He) in the presence of density gradients in SF helium (HeII), we show that nonresonance microwave absorption in the frequency range 170-200 GHz can be due to the existence of time-varying local density gradients produced by roton excitations in the bulk HeII. The absorption bandwidth is determined by the roton-roton scattering time in an equilibrium Boltzmann gas of rotons, which is t{sub r-r} Almost-Equal-To 3.4 Multiplication-Sign 10{sup -11} s at T = 1.4 K and decreases upon heating. We propose that the anomalously narrow microwave resonance absorption line in HeII at the roton frequency f{sub 0}(T) = {Delta}r(T)/2{pi}h appears due to the following two factors: (i) the discrete structure of the spectrum of the surface EM resonator modes in the form of a periodic sequence of narrow peaks and (ii) the presence of a stationary dipole layer in HeII near the resonator surface, which forms due to polarization of {sup 4}He atoms under the action of the density gradient associated with the vanishing of the density of the SF component at the solid wall. For this reason, the relaxation of nonequilibrium rotons generated in such a surface dipole layer is strongly suppressed, and the shape and width of the microwave resonance absorption line are determined by the roton density of states, which has a sharp peak at the edge of the roton gap in the case of weak dissipation. The effective dipole moments of rotons in the dipole layer can be directed either along or across the normal to the resonator surface, which explains the experimentally observed symmetric doublet splitting of the resonance absorption line in an external dc electric field perpendicular to the resonator surface. We show that negative absorption (induced emission) of EM field quanta observed after triggering a Kapitza 'heat gun' occurs when the occupation numbers for roton states due to 'pumping' of rotons exceed the occupation numbers of EM field photons in the resonator.

  18. Energy spectrum of anomalous positrons

    Microsoft Academic Search

    J. D. Fox; K. W. Kemper; P. D. Cottle

    1995-01-01

    It is suggested that nuclear reactions induced by medium mass projectiles, with A\\/q close to that of the primary beam, could explain the anomalous positron-electron peaks observed in sub-barrier collisions of very heavy nuclei. The reactions result in prominent gamma-rays which convert to e+e- pairs in material near the target. Possible experiments to examine this hypothesis are suggested.

  19. Energy spectrum of anomalous positrons

    Microsoft Academic Search

    J. D. Fox; K. W. Kemper; P. D. Cottle

    1995-01-01

    It is suggested that nuclear reactions induced by medium mass projectiles, with A\\/q close to that of the primary beam, could explain the anomalous positron-electron peaks observed in sub-barrier collisions of very heavy nuclei. The reactions result in prominent ?-rays which convert to e+e- pairs in material near the target. Possible experiments to examine this hypothesis are suggested.

  20. Faraday anomalous dispersion optical filters

    NASA Technical Reports Server (NTRS)

    Shay, T. M.; Yin, B.; Alvarez, L. S.

    1993-01-01

    The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.