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Title: Ablation dynamics in wire array Z-pinches under modifications on global magnetic field topology

The dynamics of ablation streams and precursor plasma in cylindrical wire array Z-pinches under temporal variations of the global magnetic field topology is investigated through experiments and numerical simulations. The wire arrays in these experiments are modified by replacing a pair of consecutive wires with wires of a larger diameter. This modification leads to two separate effects, both of which impact the dynamics of the precursor plasma; firstly, current is unevenly distributed between the wires and secondly, the thicker wires take longer to fully ablate. The uneven distribution of current is evidenced in the experiments by the drift of the precursor off axis due to a variation in the global magnetic field topology which modifies the direction of the ablation streams tracking the precursor position. The variation of the global magnetic field due to the presence of thick wires is studied with three-dimensional magnetohydrodynamic (MHD) simulations, showing that the global field changes from the expected toroidal field to a temporally variable topology after breakages appear in the thin wires. This leads to an observed acceleration of the precursor column towards the region closer to the thick wires and later, when thick wires also present breakages, it continues moving away frommore » the original array position as a complicated and disperse object subject to MHD instabilities.« less
Authors:
; ; ; ; ;  [1] ; ; ;  [2]
  1. Instituto de Física, Pontificia Universidad Católica de Chile, Av Vicuña Mackenna 4860, Macul, Santiago (Chile)
  2. Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)
Publication Date:
OSTI Identifier:
22490971
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 7; 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; ABLATION; COMPUTERIZED SIMULATION; CURRENTS; CYLINDRICAL CONFIGURATION; DISTRIBUTION; INSTABILITY; LINEAR Z PINCH DEVICES; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PLASMA; THREE-DIMENSIONAL CALCULATIONS; TOPOLOGY; WIRES