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  • 1
    Electronic Resource
    Electronic Resource
    Density sensitive line ratios for highly ionized atoms of the Cu i and Na i isoelectronic sequences (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3947-3952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We discuss extreme ultraviolet and x-ray spectral lines emitted by ions of the Cu i and Na i isoelectronic sequences and show that certain intensity ratios of these lines are sensitive to electron density in the range from about 1018 to 1022 cm−3. These lines therefore provide density diagnostics for high-temperature plasmas. We illustrate the density dependence for four ions of the Cu i sequence (Z=60, 71, 82, 92) and seven ions of the Na i sequence (Z=32, 42, 52, 62, 72, 82, 92). We also show that the dependence of the ratios on electron temperature is not strong, and demonstrate that opacity can be kept small by employing the spot spectroscopy technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346280
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  • 2
    Electronic Resource
    Electronic Resource
    Inner-shell x-ray line spectra of highly ionized titanium, chromium, iron, and nickel and their application to laboratory plasmas (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1960-1973 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The intensities of x-ray lines due to inner-shell 1s-2p transitions in O i-, N i-, and C i-like ions of Ti xv–xvii, Cr xvii-xix, Fe xix-xxi, and Ni xxi-xxiii seen in tokamak plasmas are calculated. The lines are assumed to be formed by dielectronic recombination and inner-shell excitation. The present calculations are an extension of previous work for iron alone. The dielectronic contribution for iron was found to be more important, and this is true for the ions of titanium, chromium, and nickel considered here. The dielectronic rates were calculated using a suite of computer programs developed by one of us. The inner-shell contribution was estimated by van Regemorter's formula. The considered ion stages have two or more fine-structure levels in the ground configuration, which gives rise to a density dependence of both dielectronic and collision excitation mechanisms at densities between 1011 and 1016 cm−3, a range suitable for tokamak plasmas. A means for determining the density of high-temperature plasmas is presented for when no other density diagnostics are available. Finally, the present calculations were applied to the problem of radial ion diffusion in tokamaks. Spectra were calculated by integrating along various lines of sight to simulate what might be observed by an actual spectrometer viewing a tokamak plasma. The assumed temperature and density profiles and two diffusion models were taken from a recent calculation. A method for determining the diffusion coefficient from tokamak observations is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337197
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  • 3
    Electronic Resource
    Electronic Resource
    3s–3p laser gain and x-ray line ratios for the carbon isoelectronic sequence (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 3953-3957 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The populations of the 46 levels belonging to the configurations 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p, and 2s22p3d have been calculated for ions in the C I isoelectronic sequence with atomic numbers Z=18, 22, 26, 30, 34, and 36 and for electron densities from 1015 to 1022 cm−3. The populations of the 2s22p3p levels are relatively large owing to the large electron collisional monopole excitation rates from the ground configuration and to the small radiative decay rates to the ground configuration. This results in population inversions for transitions of the type 3s–3p. The gain coefficients for these transitions are determined and are compared to previous calculations. At high electron densities where collisional mixing of the excited levels becomes important, the intensities of the x-ray transitions from the 2s22p3p levels to the 2s2p3 levels decrease relative to the x-ray transitions from the 2s22p3s and 2s22p3d levels. The density dependence of these x-ray line ratios is also presented. These line ratios represent a promising diagnostic for electron density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336695
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  • 4
    Electronic Resource
    Electronic Resource
    Short wavelength laser calculations for electron pumping in Be I and B I isoelectronic sequences (18≤Z≤36) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 2909-2915 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Level populations of the 2s3p and 2s23p configurations in ions of the Be I and B I isoelectronic sequences can be inverted, with respect to populations of the 2s3s and 2s23s configurations, by electron collisional pumping. In the case of B I ions, the process is analogous to the process for Ne-like ions, which has lately received considerable attention. In the case of Be I ions, the inversion is a consequence of the slow radiative decay of the 2s3p 3P2 and 2s3p 3P0 levels. Level populations are calculated for Be- and B-like ions with atomic number Z between 18 and 36. For each sequence, 20 levels are involved with principal quantum number n equal either to two or three. Using the level populations, gain coefficients are calculated for transitions of the type 2s3s−2s3p and 2s23s−2s23p. Finally, the opacity of the 2s2p−2s3s and 2s22p−2s23s transitions are discussed, for plasma parameters for which a reasonable gain can be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335838
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of resonance excitation due to dielectronic capture on the gain coefficients of selected transitions in Fe XVII (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 3984-3986 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In previous papers, U. Feldman, J. F. Seely, and A. K. Bhatia [J. Appl. Phys. 56, 2475 (1984)] and A. K. Bhatia, U. Feldman, and J. F. Seely [At. Data Nucl. Data Tables (in press)] have calculated atomic data and gain coefficients for ions of the Ne I isoelectronic sequence. Their calculations of electron impact excitation rates were carried out in the distorted wave approximation. They did not include the effect of resonance excitation, i.e., dielectronic capture by a Ne-like ion followed by autoionization leaving the Ne-like ion in an excited state. In this paper, we use the recent calculations of this process by B. W. Smith, J. C. Raymond, J. B. Mann, and R. D. Cowan [Astrophys. J. (in press)] to explore the effect of resonance excitation on gain coefficient calculations for the ion Fe XVII. We find substantial differences (factors of about 1.3–3) between gain coefficient calculations with and without the inclusion of resonances at low temperatures. However, these effects are not important at the temperatures considered by Feldman, Seely, and Bhatia for Fe XVII.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335573
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  • 6
    Electronic Resource
    Electronic Resource
    The NASA high energy solar physics (HESP) mission for the next solar maximum
    Amsterdam : Elsevier
    Advances in Space Research 13 (1993), S. 401-410 
    Details
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0273-1177(93)90512-A
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  • 7
    Electronic Resource
    Electronic Resource
    Solar instruments on the P78-1 spacecraft (1983)
    Springer
    Solar physics 86 (1983), S. 9-17 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The solar experiment package on the P78-1 spacecraft is described. The satellite was launched on 24 February 1979 by the U.S. Air Force and contains high resolution Bragg crystal spectrometers, hard X-ray proportional counters, and a white light coronagraph. The high resolution spectrometers were built by the Aerospace Corporation and the Naval Research Laboratory. The hard X-ray spectrometers were built by the Aerospace Corporation and the white light coronagraph was supplied by the Naval Research Laboratory. Most of these instruments are still returning data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157170
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  • 8
    Electronic Resource
    Electronic Resource
    Discussion of paper ‘on the polarization and anisotropy of solar X-radiation during flares’, by G. Elwert and E. Haug (1971)
    Springer
    Solar physics 20 (1971), S. 422-424 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159774
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  • 9
    Electronic Resource
    Electronic Resource
    Note on heliumlike silicon and sulfur lines observed in the X-ray spectra of solar flares (1973)
    Springer
    Solar physics 28 (1973), S. 517-518 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152321
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  • 10
    Electronic Resource
    Electronic Resource
    The Bragg Crystal Spectrometer for SOLAR-A (1991)
    Springer
    Solar physics 136 (1991), S. 89-104 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Bragg Crystal Spectrometer (BCS) is one of the instruments which makes up the scientific payload of the SOLAR-A mission. The spectrometer employs four bent germanium crystals, views the whole Sun and observes the resonance line complexes of H-like Fexxvi and He-like Fexxv, Caxix, and Sxv in four narrow wavelength ranges with a resolving power (λ/Δλ) of between 3000 and 6000. The spectrometer has approaching ten times better sensitivity than that of previous instruments thus permitting a time resolution of better than 1 s to be achieved. The principal aim is the measurement of the properties of the 10 to 50 million K plasma created in solar flares with special emphasis on the heating and dynamics of the plasma during the impulsive phase. This paper summarizes the scientific objectives of the BCS and describes the design, characteristics, and performance of the spectrometers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151696
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