Plasma formation and implosion structure in wire array Z pinches

The transformation of a cylindrical array of metallic wires into an implodi ng Z-pinch plasma is described using a 2D resistive magnetohydrodynamics co de. The persistence of unionized wire cores dominates the collapse structur e. Low-density coronal plasma is swept around the wire cores generating rad ial plasma streams which reach the axis forming a precursor plasma at rough ly half the implosion time. The final stagnation comprises high-density pla sma streams impacting onto this precursor. Azimuthal modulation of the plas ma is retained throughout. The code accurately reproduces a number of featu res of experiments with 1 MA currents and predicts qualitatively similar re sults for higher currents.