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Title: Particle-in-cell δf gyrokinetic simulations of the microtearing mode

The linear stability properties of the microtearing mode are investigated in the edge and core regimes of the National Spherical Torus Experiment (NSTX) using the particle-in-cell method based gyrokinetic code GEM. The dependence of the mode on various equilibrium quantities in both regions is compared. While the microtearing mode in the core depends upon the electron-ion collisions, in the edge region, it is found to be weakly dependent on the collisions and exists even when the collision frequency is zero. The electrostatic potential is non-negligible in each of the cases. It plays opposite roles in the core and edge of NSTX. While the microtearing mode is partially stabilized by the electrostatic potential in the core, it has substantial destabilizing effect in the edge. In addition to the spherical tokamak, we also study the microtearing mode for parameters relevant to the core of a standard tokamak. The fundamental characteristics of the mode remain the same; however, the electrostatic potential in this case is destabilizing as opposed to the core of NSTX. The velocity dependence of the collision frequency, which is crucial for the mode to grow in slab calculations, is not required to destabilize the mode in toroidal devices.
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)
  2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
  3. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
Publication Date:
OSTI Identifier:
22493822
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 1; Other Information: (c) 2016 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; COMPUTER CODES; ELECTRON-ION COLLISIONS; NSTX DEVICE; PLASMA SIMULATION; POTENTIALS; SLABS; SPHERICAL CONFIGURATION; STABILITY; TEARING INSTABILITY; TOROIDAL CONFIGURATION