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  • 1
    Electronic Resource
    Electronic Resource
    GERMANIUM. XXXV. GERMANIUM MONOXIDE. GERMANIUM MONOSULFIDE1 (1930)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 52 (1930), S. 3553-3556 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01372a010
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of soft x-ray average recombination coefficient and average charge for metallic impurities in beam-heated plasmas (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2148-2150 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The soft x-ray continuum radiation in tokamak fusion test reactor (TFTR) low-density neutral-beam discharges can be much lower than its theoretical value obtained by assuming a corona equilibrium. This reduced continuum radiation is caused by an ionization equilibrium shift toward lower states, which strongly changes the value of the average recombination coefficient of metallic impurities γ¯, even for only slight changes in the average charge Z¯. The primary agent for this shift is the charge exchange between the highly ionized impurity ions and the neutral hydrogen, rather than impurity transport, because the central density of the neutral hydrogen is strongly enhanced at lower plasma densities with intense beam injection. In the extreme case of low-density, high neutral-beam power TFTR operation (energetic ion mode) the reduction in γ¯ can be as much as one-half to two-thirds. We calculate the parametric dependence of γ¯ and Z¯ for Ti, Cr, Fe, and Ni impurities on neutral density (equivalent to beam power), electron temperature, and electron density. These values are obtained by using either a one-dimensional impurity transport code or a zero-dimensional code with a finite particle confinement time. As an example, we show the variation of γ¯ and Z¯ in different TFTR discharges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138712
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Measurements of radial profiles of the ion temperature and the plasma rotation velocity with the TFTR vertical x-ray crystal spectrometer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2131-2134 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The TFTR vertical x-ray crystal spectrometer has now been operating with three crystals and position-sensitive detectors according to the original design specifications. The observed spectra of heliumlike Ti xxi, Cr xxiii, Fe xxv, and Ni xxvii have permitted a detailed comparison with the predictions from atomic theories, and they have provided data on the radial profiles of the ion temperature and toroidal rotation velocity, as well as the radial ion charge-state distribution in TFTR discharges. Central ion temperatures of 20 keV and central plasma rotation velocities of 5×105 m/s have been recorded from plasmas with auxiliary neutral beam heating. These experimental results are presented. Also discussed are further instrumental improvements, such as the installation of two additional crystals and detectors and the installation of γ and neutron shielding, which will make it possible to measure under full DD and DT operation with 27 MW of neutral beam injection where neutron production rates of 1019 neutrons/s are expected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139975
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  • 4
    Electronic Resource
    Electronic Resource
    High-resolution bent-crystal spectrometer for the ultrasoft x-ray region (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 895-906 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A multichannel vacuum Bragg-crystal spectrometer has been developed for high-resolution measurements of the line emission from tokamak plasmas in the wavelength region between 4 and 25 A(ring). The spectrometer employs a bent crystal in Johann geometry and a microchannel-plate-intensified photodiode diode array. The instrument is capable of measuring high-resolution spectra (λ/Δλ≈3000) with fast time resolution (4 ms per spectrum) and good spatial resolution (3 cm). The spectral bandwidth is Δλ/λ0=15% at λ0=8 A(ring). A simple tilt mechanism allows access to different wavelength intervals. In order to illustrate the utility of the new spectrometer, time- and space-resolved measurements of the n=3–2 spectrum of selenium from the Princeton Large Torus tokamak plasmas are presented. The data are used to determine the plasma transport parameters and to infer the radial distribution of fluorinelike, neonlike, and sodiumlike ions of selenium in the plasma. The new ultrasoft x-ray spectrometer has thus enabled us to demonstrate the utility of high-resolution L-shell spectroscopy of neonlike ions as a fusion diagnostic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140341
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  • 5
    Electronic Resource
    Electronic Resource
    Utilization of charge exchange recombination spectroscopy for the study of metallic ion transport in TFTR (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1518-1520 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Charge exchange recombination spectroscopy has been used to observe transitions originating from hydrogen-, helium-, and lithiumlike charge states of medium-Z metallic impurities in TFTR. The temporal and spatial densities of these ions were measured in ohmic and neutral beam heated plasmas. These preliminary results agree with predictions of a transport code.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140182
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  • 6
    Electronic Resource
    Electronic Resource
    Excitation rates for plasma impurity measurements by x-ray diagnostics (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1825-1827 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurement of intrinsic and injected impurity concentrations and transport in tokamak plasmas by x-ray pulse-height analysis (PHA) and x-ray imaging (XI) diode arrays requires reliable excitation rates for a number of charge states of a range of elements (Al, Se, Ti, Cr, Fe, Ni, Ge, etc.). Previous PHA measurements at Princeton have relied on a coronal-equilibrium average of excitation rates for iron, and a prescription for scaling the average rate to nearby elements. For improved accuracy in PHA measurements (using the MIST impurity equilibrium and transport code) and for interpretation of XI data (using an x-ray simulation code), rates for excitation of dominant charge states by electron impact, dielectronic recombination, and radiative recombination have been calculated from available atomic data and parametrized as a function of atomic number (Z=10–42) and electron temperature (Te =0.1–10.0 keV).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140072
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Measurements of radial profiles of the ion temperature and the plasma rotation velocity with the TFTR vertical x-ray crystal spectrometer (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1852-1852 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The TFTR vertical x-ray crystal spectrometer has now been operating with three crystals and position-sensitive detectors according to the original design specifications. The observed spectra of heliumlike Ti xxi, Cr xxiii, Fe xxv, and Ni xxvii have permitted a detailed comparison with the predictions from atomic theories, and they have provided data on the radial profiles of the ion temperature and toroidal rotation velocity, as well as the radial ion charge-state distribution in TFTR discharges. Central ion temperatures of 20 keV and central plasma rotation velocities of 5×105 m/s have been recorded from plasmas with auxiliary neutral beam heating. These experimental results are presented. Also discussed are further instrumental improvements, such as the installation of two additional crystals and detectors and the installation of γ and neutron shielding, which will make it possible to measure under full DD and DT operation with 27 MW of neutral beam injection where neutron production rates of 1019 neutrons/s are expected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140086
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of steady-state and perturbative transport coefficients in TFTR (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2315-2323 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Steady-state and perturbative transport analysis are complementary techniques for the study of transport in tokamaks. These techniques are applied to the investigation of auxiliary-heated L-mode and supershot plasmas in the tokamak fusion test reactor (TFTR) [R. J. Hawryluk et al., Plasma Physics and Controlled Nuclear Fusion Research, Proceedings of the 11th International Conference, Kyoto, 1986 (IAEA, Vienna, 1987), Vol. 1, p. 51.]. In the L mode, both steady-state and perturbative transport measurements reveal a strong temperature dependence that is consistent with electrostatic microinstability theory and the degradation of confinement with neutral beam power. Steady-state analysis of the ion heat and momentum balance in supershots indicates a reduction and a significant weakening of the power-law dependence on the transport in the center of the discharge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859598
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  • 9
    Electronic Resource
    Electronic Resource
    On the Murakami density limit in tokamaks and reversed-field pinches (1985)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 28 (1985), S. 1837-1844 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical upper limit for the density in an Ohmically heated tokamak discharge follows from the requirement that the Ohmic heating power deposited in the current-carrying channel exceed the impurity radiative cooling in this critical region. A compact summary of our results gives this limit nM for the central density as nM =[Ze/(Ze−1)]1/2 ne0 (BT /1T) (1m/R), where ne0 depends strongly on the impurity species and is remarkably independent of the central electron temperature Te(0). For Te(0) ∼1 keV, ne0 =1.5×1014 cm−3 for beryllium, ne0 =5.5×1013 cm−3 for oxygen, ne0 =1.0×1013 cm−3 for iron and, ne0 =0.5×1013 cm−3 for tungsten. The results agree quantitatively with Murakami's original observations. A similar density limit, known as the I/N limit, exists for reversed-field pinch devices and this limit has also been evaluated for a variety of impurity species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.864927
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  • 10
    Electronic Resource
    Electronic Resource
    Helium, iron, and electron particle transport and energy transport studies on the Tokamak Fusion Test Reactor (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2215-2228 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results from helium, iron, and electron transport studies on the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. 26, 11 (1984)] in L-mode and supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the supershot. The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the supershot, differences are found in the L mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of 3 larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860755
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