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  • 1
    Electronic Resource
    Electronic Resource
    On comparison of spectroscopically deduced central ion temperatures and plasma rotation at JET (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2241-2247 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is shown that a significant increase in the consistency of charge exchange spectroscopy and x-ray spectroscopy data for central ion temperature and plasma rotation is obtained when allowance is made for the following: (i) The charge exchange cross-section dependence on the impact energy of the neutral beam atoms in the frame-of-reference of the C+6 nuclei. In this paper we have experimentally verified the predicted cross-section effects on plasma rotation measurements using charge exchange spectroscopy by comparing to passive x-ray spectroscopy. The effect increases with lighter species. It should be emphasized that this effect is important for the rotation measurements only, while for the ion temperature measurements the effect is small compared to other error sources. (ii) The precise position of the radiating ion shell in line-of-sight averaged measurements using x-ray spectroscopy. For high-temperature plasmas with broad emission profiles the uncertainty in central ion temperature is reduced from up to 60% to the order of 20%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143145
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Neutron profile measurements for trace tritium experiments : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1123-1125 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The JET neutron profile monitor was used to study the transport of tritium into a magnetically confined deuterium plasma. Trace amounts of tritium were introduced through a gas valve beyond the plasma edge into a variety of plasma confinement regimes. The d(t,n)α fusion cross section is two orders of magnitude greater than the d(d,n)3He cross section and so a puff of tritium which has a negligible effect on the plasma nevertheless produces a large d–t neutron signal. The profile monitor consists of two cameras each made up of a fan-shaped array of collimated lines of sight. It was used to measure the d–d and d–t neutron profiles simultaneously. This article describes the detection system, its operation and assesses the difficulties due to scattered neutrons. The profiles can be used to determine tritium density and transport coefficients. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149330
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  • 3
    Electronic Resource
    Electronic Resource
    Deduction of central plasma parameters from line-of-sight averaged spectroscopic observations (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6732-6742 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method is presented to deduce central ion temperature and toroidal rotation velocity from line-of-sight averaged x-ray spectra from hot plasmas. The analysis is based on atomic data for the processes that give rise to x-ray spectral lines. Combined with measured electron temperature and density profiles a synthetic spectrum is calculated. The fit of this synthetic spectrum to the observed one gives a new level of accuracy to line-of-sight integrated observations in a considerably extended range of ion temperatures and toroidal rotation velocities. The choice of model for radial profiles for ion temperature and toroidal rotation velocity is shown not to be critical. The concentration of the emitting impurity is deduced from the total line intensity, making use of the absolute calibration of the detector sensitivity. The effective plasma charge Zeff is derived from the absolute level of the continuum radiation. These measurements are based on atomic data for x-ray line and continuum radiation and measured electron temperature and density profiles. The results for ion temperature and toroidal rotation velocity obtained by this analysis are compared with those from visible charge exchange spectroscopy. The observed visible lines are shifted in wavelength, and their width is reduced, due to the velocity dependence of the cross section for the charge transfer from the neutral beam particles to the observed impurities. The theoretically predicted magnitude of these effects is verified. When the results from visible charge exchange spectroscopy are corrected for the cross-section effects, excellent agreement of central ion temperature and rotation velocity with the results of this new analysis is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350369
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    Paper (German National Licenses)
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