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  • 1
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    Dynamic properties of helium ions in the solar wind (1995)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: We characterize the dynamic properties of He ions of the solar wind. Because of the non-negligible abundance and the significant fraction of momentum flux inherent in helium ions, this species has an influence on the state of turbulence. Especially, we analyze the helium dynamic properties of different solar wind types. After a discussion of the influence of measurement errors on the statistical analysis of He bulk velocities, we investigate the structure function dependency on the solar wind state. We find a self-similar sealing in the range of minutes to days with characteristic structure function slopes deviating from the canonical Kolmogorov values. For comparison with previous studies, we also analyze H structure functions of the same time periods and discuss differences of coinciding He and H structure functions in the framework of the concept of intermittency.
    Keywords: Solar Physics
    Type: International Solar Wind 8 Conference; 73; NASA-CR-199940
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    NASA TECHNICAL REPORTS
  • 2
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    Test particle study of minor ions in solar wind turbulence (1995)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: We perform a parameter study of the temporal evolution of a test particle distribution function in MHD turbulence. The turbulent fields are calculated using a pseudo-spectral method and periodic boundary conditions on a regular grid of 180(exp 3) points, appropriate for incompressible, homogeneous and isotropic turbulence. Initially, the kinetic and the magnetic energy are equal on the average. Both, deterministic and random initial conditions are used, in the former case with zeros of the magnetic field located at grid points, in the latter case located by interpolation between grid points. The evolution of the minor ion distribution function is studied in detail as these turbulent fields evolve, developing strong current and vorticity sheets. Using the full collisionless equation of motion for the test particles, the efficiency of nonlinear interactions can be studied. The results are compared to theoretical predictions and are then discussed in connection with the observations of the dynamical properties of solar wind minor ions derived from in situ observations.
    Keywords: Solar Physics
    Type: ; 82
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  • 3
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    Some features of the small-scale solar wind fluctuations (1995)
    In:  Other Sources
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    Publication Date: 2019-07-17
    Description: We have investigated small-scale variations of the solar wind ion flux measured with Faraday cups onboard the Prognoz-8 satellite. These measurements have a high time resolution of 1.24 seconds for intervals with a duration of several hours and as high as 0.02 seconds for some periods of about 1 hour duration. The main goal of this work is the determination of the quantitative features of fast ion flux fluctuations using mainly spectral analysis but also other methods. We also identify their association with interplanetary plasma parameters. Particularly, it is shown that the slope of the power spectra in the frequency range from 1E-4 to 6E-2 Hz is close to the classical Kolmogorov (-5/3) law. We also discuss some intervals with a very high level of the relative amplitude of flux fluctuations (10-20 percent) which were observed near the Earth's bow shock in the foreshock region. The use of the wavelet method for the long time series allows us to study the temporal evolution of power spectra.
    Keywords: Solar Physics
    Type: ; 82
    Format: text
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  • 4
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    Elemental composition in the slow solar wind measured with the MASS instrument on WIND (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The MASS instrument on WIND contains the first isochronous time-offlight spectrometer to be flown in the solar wind. The first spectra obtained with this instrument has demonstrated its capability to measure the abundances of several high-and low-FIP elements in the solar wind. The derivation of these abundances requires a careful calibration of the charge exchange efficiencies of the relevant ions in carbon foils. These efficiencies and the corresponding instrument functions have been determined in extensive calibration campaigns at different institutions. We present first and preliminary results obtained in slow solar wind streams and we compare these results with those obtained from previous investigations of solar wind abundances and of coronal abundances as derived from Solar Energetic Particles. Recent models of the FIP related fractionation effect predict a depletion of a factor of typically 4 to 5 for high-FIP elements (He, N, O, Ne, Ar, etc.) relative to low-FIP elements (Mg, Fe, Si, etc.). We also compare our results with the detailed predictions of the different models and we discuss the resulting evidence to validate or to invalidate different physical scenarios explaining the feeding and the acceleration of slow stream solar wind.
    Keywords: Solar Physics
    Type: ; 35
    Format: text
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  • 5
    Electronic Resource
    Electronic Resource
    Packing and stationary phase design for capillary electroendosmotic chromatography (CEC) (1999)
    Springer
    Chromatographia 49 (1999), S. S49 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrochromatography ; Electroosmotic flow ; Submicron silica beads ; Mixed mode phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase stationary phases based on porous silica beads in the range 0.2–3 μm have been prepared to study the dependency of electroosmotic flow (EOF) on particle diameter. Additionally, the influence of the mobile phase composition, i.e. organic modifier content, pH of buffer solution and concentration of buffer salt, on the magnitude of the electroosmotic flow velocity has been investigated. To perform separations in an aqueous acidic mobile-phase, mixed mode stationary phases containing both alkyl chains and strong cationexchange groups have been applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02468976
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of active ingredients and preservatives in creams by capillary electrochromatography (CEC) (1999)
    Springer
    Chromatographia 49 (1999), S. S35 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrochromatography ; Packing materials ; Mixed-mode phase ; Active ingredients and preservatives in creams ; Cortisone derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capillary electrochromatography (CEC) is an analytical method of growing interest to the pharmaceutical industry. Because CEC is a combination of high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) it has the advantages of the high selectivity of HPLC and the high efficiency of CE. The capillaries can be packed with different packing materials. The mixed-mode phase consisting of a strong cation exchanger and alkyl chains on the silica surface has some advantages over conventional reversed-phase (RP) packing materials. In this article the authors describe the use of CEC to separate the active ingredients and preservatives in creams from different manufactures. On the basis of the high efficiency of CEC it was possible to develop one isocratic method for all the compounds in the different samples. The method was validated with regard to identification, reproducibility, linearity, limit of detection, and quantitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02468974
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  • 7
    Electronic Resource
    Electronic Resource
    Analyte identification in capillary electrophoretic separation techniques (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2753-2776 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Capillary electrochromatography ; Analyte identification ; Spectrometric detection ; Review ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A review on applications of on-line hyphenation in capillary electrophoresis and capillary electrochromatography for the identification of migrating analytes is presented. There is an urgent need for unambiguous analyte identification by combining spectral information and observed migration times, because the parameters influencing the migration times and separation efficiencies in these separation techniques are not easily controlled, especially when real samples containing unknown interferences have to be analyzed. The spectrometric techniques covered here are ultraviolet and visible radiation (UV/Vis) absorption, fluorescence including fluorescence line-narrowing spectroscopy, Raman spectroscopy, nuclear magnetic resonance and mass spectrometry. Attention is essentially confined to literature reports in which the extra information provided by the detector is really used for identification purposes, especially in real-life samples, while the interfacing as such and analyte detectabilities in standard solutions are only briefly discussed. This article covers an extensive fraction of the literature published on this topic until the beginning of 1998.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191604
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