Fast ion charge exchange spectroscopy measurement using a radially injected neutral beam on the large helical device

M. Osakabe, S. Murakami, M. Yoshinuma, K. Ida, A.D. Whiteford, M. Goto, D. Kato, T. Kato

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Abstract

An experimental technique to investigate fast ion confinement based on charge exchange spectroscopy of Hα-light was applied to evaluate the confinement property of perpendicular fast ions in large helical device (LHD). Sensitivities of the Hα spectra to the pitch angles of injected neutral beams (NBs) and these to the angle between the sight line of the measurement and NB injection path are examined. The energy dependence of the charge exchange cross section significantly affects the observed spectra since the driving NB is injected perpendicular to the magnetic field lines in the geometry of LHD. The measured spectra are compared to the spectra of GNET simulation results and the simulated spectra agreed well with the experimental measurement when we take into account the contribution of halo neutrals. Although it is difficult to obtain the fast ion distribution functions directly, this technique provides useful experimental data in benchmarking simulation codes.
Original languageEnglish
Pages (from-to)10E519-10E519
JournalReview of Scientific Instruments
Volume79
Issue number10
DOIs
Publication statusPublished - 28 Oct 2008

Keywords

  • charge exchange
  • plasma beam injection heating
  • plasma confinement
  • plasma diagnostics

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    Osakabe, M., Murakami, S., Yoshinuma, M., Ida, K., Whiteford, A. D., Goto, M., ... Kato, T. (2008). Fast ion charge exchange spectroscopy measurement using a radially injected neutral beam on the large helical device. Review of Scientific Instruments, 79(10), 10E519-10E519. https://doi.org/10.1063/1.2968695