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Title: Resistive magnetohydrodynamic simulations of helicity-injected startup plasmas in National Spherical Torus eXperiment

The generation of helicity-injected startup plasmas in National Spherical Torus eXperiment (NSTX), including flux surface closure, is studied using resistive-magnetohydrodynamic simulations with plasma flows, currents, ohmic heating and anisotropic thermal conduction. An injection-voltage pulse shape is used that separates the injection and closure phases allowing elucidation of the physics. The formation of an X-point near the helicity-injection gap is triggered as the injector voltage drops to zero. Near the forming X-point, magnetic pressure due to toroidal field entrained in the E × B plasma flow from the helicity-injection gap drops, allowing resistive magnetic reconnection even though the total injected current is almost constant. Where appropriate, the simulations are compared with Transient Coaxial Helicity Injection experiments in the NSTX spherical tokamak, which have demonstrated the formation of a promising candidate for non-inductive startup plasmas [Raman et al., Phys. Rev. Lett. 90, 075005 (2003)].
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  2. Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)
  3. Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)
  4. Department of Astrophysical Sciences, Princeton University, New Jersey 08544 (United States)
  5. (United States)
  6. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
Publication Date:
OSTI Identifier:
22220611
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 9; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; HELICAL CONFIGURATION; MAGNETIC RECONNECTION; MAGNETIC SURFACES; MAGNETOHYDRODYNAMICS; NSTX DEVICE; PLASMA; PLASMA CONFINEMENT; PLASMA SIMULATION; SPHERICAL CONFIGURATION; THERMAL CONDUCTION; THERMONUCLEAR IGNITION