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Title: Laboratory observation of magnetic field growth driven by shear flow

Two magnetic flux ropes that collide and bounce have been characterized in the laboratory. We find screw pinch profiles that include ion flow v{sub i}, magnetic field B, current density J, and plasma pressure. The electron flow v{sub e} can be inferred, allowing the evaluation of the Hall J×B term in a two fluid magnetohydrodynamic Ohm's Law. Flux ropes that are initially cylindrical are mutually attracted and compress each other, which distorts the cylindrical symmetry. Magnetic field is created via the ∇×v{sub e}×B induction term in Ohm's Law where in-plane (perpendicular) shear of parallel flow (along the flux rope) is the dominant feature, along with some dissipation and magnetic reconnection. We predict and measure the growth of a quadrupole out-of-plane magnetic field δB{sub z}. This is a simple and coherent example of a shear flow driven dynamo. There is some similarity with two dimensional reconnection scenarios, which induce a current sheet and thus out-of-plane flow in the third dimension, despite the customary picture that considers flows only in the reconnection plane. These data illustrate a general and deterministic mechanism for large scale sheared flows to acquire smaller scale magnetic features, disordered structure, and possibly turbulence.
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Los Alamos National Laboratory, M.S. E526, Los Alamos, New Mexico 87545 (United States)
  2. Applied Materials, Inc., Santa Clara, CA 95054 (United States)
  3. University of Science and Technology, Hefei (China)
Publication Date:
OSTI Identifier:
22253134
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 4; Other Information: (c) 2014 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; CURRENT DENSITY; CYLINDRICAL CONFIGURATION; IONS; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIC RECONNECTION; OHM LAW; PLASMA PRESSURE; SCREW PINCH; SHEAR