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  • 1990-1994  (6)
  • 1
    Electronic Resource
    Electronic Resource
    A novel multichord spectrometer for plasma velocity measurements : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5164-5166 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A diagnostic has been designed to study edge plasma velocities in (JET) with good space and time resolution. To eliminate ambiguities in the measurement arising from atomic physics effects opposing views are provided. Each viewing direction incorporates ten fibers imaged on the path of a neutral heating beam with a channel spacing of 1.5 cm. The chord views are imaged onto a spectrometer with 20 individual entrance slits arranged in a rectangular array. The dispersed spectra from adjacent slits form linear images 25 mm long that are recorded using four fast optical multichannel analyzers. To prevent crosstalk of signals from adjacent slits the instrument incorporates a low dispersion spectrometer to limit the bandpass of the system. The principal advantage of this design is the ability to match the f number of the fiber optic arrays. This results from the rectangular arrangement of the slits which allows for a 4× magnification of the fiber images without requiring an exceptionally long (70 mm) entrance slit. This matching optimises the light collection efficiency of the complete diagnostic which ultimately sets the shortest time resolution. The minimum readout time for all 20 channels is 0.5 ms, although longer integration times are generally needed in JET.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143468
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    General purpose high-resolution x-ray crystal spectrometer (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5022-5022 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This spectrometer was designed to give access to a wide range of Bragg angles and crystal focal lengths while using the Rowland circle radius as a free parameter. Stability is achieved using a rigid beam or "Rowland chord,'' which provides a reference axis for all the critical alignments, the chord length being variable between about 0.2 and 5 m. Crystals of size up to 100×30×0.5 mm can be accommodated in a novel four-pillar jig, (λ/δλ) is typically 104 in the wavelength range from 0.1 to 1.3 nm, depending on the crystal. Various detectors have been used, including photographic film, multiwire gas proportional counters and large area CCD detectors, the latter having a 2-D spatial resolution of 22.5 μm (1152×1242 pixels, 26×28 mm2), a quantum efficiency greater than 20% between 0.7 and 12 keV and an energy resolution of about 150 eV. By sacrificing energy resolution, a one-dimensional mode with on-chip binning allows ∼ms time resolution of spectra from high flux sources such as tokamaks and synchrotrons. Results presented include photographic spectra from tokamak, beam foil and laser produced sources, and CCD spectra from tokamak and standard electron-beam excitation laboratory sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143478
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Bragg spectroscopy of impurities during the JET preliminary tritium experiment : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5023-5025 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two Bragg spectrometers shared a shielded beamline, and monitored all significant plasma impurities throughout the Joint European Torus (JET) preliminary tritium experiment. The JET Active Phase Double Crystal Monochromator and a Bragg rotor spectrometer together monitored K-shell lines of Be, C, O, and Cl, and L-shell lines from metals such as Ni and Zn, in the wavelength range 0.2–11 nm. Background radiation was recorded during and after discharges, to assess the signal-to-noise ratio, and to monitor any activation or tritium ingress. Bragg spectroscopy was shown to be suitable for all impurities in magnetically confined D–T plasmas, using a thin foil to isolate tritium, and a low f-number shielded beamline. Future improvements to the signal-to-noise ratio are discussed in the context of a next-step machine such as ITER.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143480
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Bragg rotor spectrometer for the JET tokamak (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5022-5022 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A Bragg rotor spectrometer uses diffractors ranging from LiF (420) (2d=0.18 nm) to a multilayer mirror (Ni–C 2d=11.7 nm). The extension to longer wavelengths is particularly useful at JET, where radiated power and Zeff are usually dominated by light impurities such as Be and C, whose H- and He-like transitions lie between about 2.5 and 10 nm. A hexagonal rotor scans six diffractors sequentially and gives either full coverage of the soft x-ray spectrum (to monitor a range of ionization stages of any possible impurity), or high monochromatic sensitivity (to monitor trace impurities and give time resolution of ∼10 μs for the study of transient events such as impurity injection). A large area gas proportional counter covers a Bragg angle range from 20° to 70°, with each of its ten anodes being connected to an independent amplifier-discriminator chain, allowing count rates up to 20 MHz to be processed. Moderate resolving power is provided by a 1:600 Soller collimator. A smaller rotor is mounted with a side-by-side array of four small diffractors, and is reciprocated over a relatively small Bragg angle range to give a time resolution of 20 ms for about ten representative lines (for routine analysis of radiated power components).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143479
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The structure of never-dried cotton fibers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 445-449 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The X-ray photographs of fresh never-dried cotton fibers are compared with those of dried fibers. The crystallite size of never-dried cotton fibers shows no significant correlation with maturity and orientation and is about the same as those of dried cotton fibers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430305
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The rigidity modulus of modified cotton fibers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 967-970 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070510519
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    Paper (German National Licenses)
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