The Detection of Fast Oxygen Ions in Neutral Beam-Heated Plasmas of the TJ-II Stellarator using Spectroscopy Methods Articles uri icon

publication date

  • July 2010

start page

  • 144020


  • 14


  • 43

International Standard Serial Number (ISSN)

  • 0953-4075

Electronic International Standard Serial Number (EISSN)

  • 1361-6455


  • During heating, by neutral beam injection, of magnetically confined plasmas in the TJ-II stellarator broad spectral structures, that straddle intense emission lines from multiply ionized oxygen ions, are
    observed by a normal-incidence spectrometer viewing a plasma region well
    separated from the neutral beam/plasma interaction volume. These
    features are seen to appear and to disappear shortly after neutral beam
    switch-on and switch-off, respectively. After excluding other possible
    origins it is demonstrated that their source is fast oxygen ions that
    originate as accelerated H2O and H3O ions in the
    ion sources of the neutral beam injectors. Next, discussions on how fast
    multiply ionized ions can perform multiple toroidal transits about this
    device, thereby giving rise to the spectral structures observed, are
    presented. Finally, implications of these emissions for spectral
    analysis and interpretation of spectra in hot magnetically confined
    plasmas are addressed.