Journal of Fusion Energy

, Volume 28, Issue 2, pp 140–143 | Cite as

The Formation of a Tokamak-like Plasma in Initial Experiments Using an Outboard Plasma Gun Current Source

  • D. J. Battaglia
  • M. W. Bongard
  • R. J. Fonck
  • A. J. Redd
  • A. C. Sontag
Original Paper

Abstract

Solenoid-free tokamak startup via point-source DC helicity injection is demonstrated on the Pegasus Toroidal Experiment using a high current density, low impurity plasma gun mounted near the outboard midplane. A threshold in the vacuum vertical magnetic field strength that allows the injected current filament to relax into a tokamak-like topology is observed. A simple 2-D model of the vacuum magnetic field suggests this threshold is the maximum field strength that allows a toroidally connected field null to form. Discharges with Ip ≈ 17 kA are produced using less than 2 kA of injected current and no inductive drive. The tokamak-like discharges exhibit current decay times about five times longer than the injected current decay, expansion of the plasma into the vacuum region and a significant increase in the line-integrated density.

Keywords

DC helicity injection Solenoid-free startup Plasma guns 

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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • D. J. Battaglia
    • 1
  • M. W. Bongard
    • 1
  • R. J. Fonck
    • 1
  • A. J. Redd
    • 1
  • A. C. Sontag
    • 1
  1. 1.Department of Engineering PhysicsUniversity of Wisconsin – MadisonMadisonUSA

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