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Title: The linear tearing instability in three dimensional, toroidal gyro-kinetic simulations

Linear gyro-kinetic simulations of the classical tearing mode in three-dimensional toroidal geometry were performed using the global gyro-kinetic turbulence code, GKW. The results were benchmarked against a cylindrical ideal MHD and analytical theory calculations. The stability, growth rate, and frequency of the mode were investigated by varying the current profile, collisionality, and the pressure gradients. Both collisionless and semi-collisional tearing modes were found with a smooth transition between the two. A residual, finite, rotation frequency of the mode even in the absence of a pressure gradient is observed, which is attributed to toroidal finite Larmor-radius effects. When a pressure gradient is present at low collisionality, the mode rotates at the expected electron diamagnetic frequency. However, the island rotation reverses direction at high collisionality. The growth rate is found to follow a η{sup 1∕7} scaling with collisional resistivity in the semi-collisional regime, closely following the semi-collisional scaling found by Fitzpatrick. The stability of the mode closely follows the stability analysis as performed by Hastie et al. using the same current and safety factor profiles but for cylindrical geometry, however, here a modification due to toroidal coupling and pressure effects is seen.
Authors:
; ; ; ; ;  [1] ; ;  [2] ;  [3]
  1. Theoretical Physics V, Department of Physics, Universitaet Bayreuth, Bayreuth D-95447 (Germany)
  2. Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching bei München (Germany)
  3. CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)
Publication Date:
OSTI Identifier:
22408071
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 2; Other Information: (c) 2015 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; BENCHMARKS; CYLINDRICAL CONFIGURATION; ELECTRONS; KINETICS; LARMOR RADIUS; MAGNETOHYDRODYNAMICS; PRESSURE DEPENDENCE; PRESSURE GRADIENTS; SIMULATION; TEARING INSTABILITY; THREE-DIMENSIONAL CALCULATIONS; TOROIDAL CONFIGURATION; TURBULENCE