Effect of discrete wires on the implosion dynamics of wire array z-pinches

A review of recent experiments at the MAGPIE facility (1MA, 250ns) at Imperial College is presented. The experiments show that the core-corona structure of the plasma, combined with the 3-D topology of the magnetic field in wire array z-pinches, results in the implosion dynamics being significantly different from that of a thin plasma shell. During the first ∼80% of the implosion time the interior of the array is gradually filled by the plasma ablated from the stationary wire cores. This phase ends with the formation of gaps in the wire cores, which occurs due to non-uniformity of the ablation rate along the wires. The final phase of the implosion, starting at this time, occurs as a rapid snowplough-like implosion of the radially distributed plasma, previously injected into the interior of the array. The density distribution of the precursor plasma being peaked on the array axis could be a key factor providing stability of wire array implosions.