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Title: Supercriticality to subcriticality in dynamo transitions

Evidence from numerical simulations suggests that the nature of dynamo transition changes from supercritical to subcritical as the magnetic Prandtl number is decreased. To explore this interesting crossover, we first use direct numerical simulations to investigate the hysteresis zone of a subcritical Taylor-Green dynamo. We establish that a well defined boundary exists in this hysteresis region which separates dynamo states from the purely hydrodynamic solution. We then propose simple dynamo models which show similar crossover from supercritical to subcritical dynamo transition as a function of the magnetic Prandtl number. Our models show that the change in the nature of dynamo transition is connected to the stabilizing or de-stabilizing influence of governing non-linearities.
Authors:
 [1] ;  [2]
  1. Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)
  2. Max-Planck-Institut für Sonnensystemforschung, Max Planck Strasse 2, 37191 Katlenburg-Lindau (Germany)
Publication Date:
OSTI Identifier:
22227944
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 7; 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; ASTROPHYSICS; COMPUTERIZED SIMULATION; HYSTERESIS; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; PLASMA; PLASMA SIMULATION; PRANDTL NUMBER