Veloso, FFVelosoMunoz-Cordovez, GGMunoz-CordovezDonoso-Tapia, LLDonoso-TapiaValenzuela-Villaseca, VVValenzuela-VillasecaSuzuki-Vidal, FFSuzuki-VidalSwadling, GGSwadlingChittenden, JJChittendenFavre, MMFavreWyndham, EEWyndham2016-05-272016-07-142015-07-14Physics of Plasmas, 2015, 22 (7)1089-7674http://hdl.handle.net/10044/1/33082The 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 from the original array position as a complicated and disperse object subject to MHD instabilities.© 2015 American Institute of Physics / AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Physics of Plasmas and may be found at http://dx.doi.org/10.1063/1.4926581Science & TechnologyPhysical SciencesPhysics, Fluids & PlasmasPhysicsX-RAY POWERENERGY DEPOSITIONENHANCEMENTLLAMPUDKENRADIATIONEXPANSIONDRIVENFluids & Plasmas0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics0201 Astronomical And Space Sciences0203 Classical PhysicsJournal Articlehttps://www.dx.doi.org/10.1063/1.4926581675350-9958