Journal of Fusion Energy

, Volume 26, Issue 1–2, pp 221–225 | Cite as

Initial Experiments at High Normalized Current in the Pegasus Toroidal Experiment

  • E. A. Unterberg
  • D. J. Battaglia
  • M. W. Bongard
  • N. W. Eidietis
  • R. J. Fonck
  • M. J. Frost
  • G. D. Garstka
  • B. A. Kujak-Ford
  • B. T. Lewicki
  • B. J. Squires
  • G. R. Winz
Article

 

Initial experiments in the Pegasus ST exhibited an operational limit of IpItf at A ∼ 1.15. With new power supplies, discharge control has greatly increased. Equilibria and stability modeling of the high Ip/Itf regime has produced stable equilibria with Ip/Itf up to 2 while values of Ip/Itf approaching 3 show a potential upper bound on stability. A new operating regime has been accessed in recent experiments with the addition of electrostatic plasma sources. Using the sources as a pre-ionization technique, Ip/Itf values of 1.5 have been accessed at very low toroidal fields. Using the sources as a means for non-inductive startup, values of Ip/Itf up to 2.3 are attained. The MHD activity in these discharges is characteristically different than ohmic discharges, suggesting the new current sources are modifying the current profile to allow stable discharge evolution at minimal toroidal field.

Keywords

Spherical torus toroidal field utilization high normalized current magnetohydrodynamic stability 

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Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • E. A. Unterberg
    • 1
  • D. J. Battaglia
    • 1
  • M. W. Bongard
    • 1
  • N. W. Eidietis
    • 1
  • R. J. Fonck
    • 1
  • M. J. Frost
    • 1
  • G. D. Garstka
    • 1
  • B. A. Kujak-Ford
    • 1
  • B. T. Lewicki
    • 1
  • B. J. Squires
    • 1
  • G. R. Winz
    • 1
  1. 1.University of WisconsinMadisonUSA

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