Implosion dynamics of z-pinch loads in two-stage wire arrays z-pinches

We will present experiments on the MAGPIE facility (1.5MA, 250ns) in which an inverse wire array¹ (with the wires acting as a return current cage placed around a central current conductor) operated as a fast current switch. This allowed to significantly reduce the rise-time of the current pulse (<;100ns) delivered to a separate, standard imploding wire array z-pinch load. The set-up also generates a current pre-pulse in the load array, which significantly changes the implosion dynamics of the load². We will discuss how pre-conditioning of the load array wires by the current pre-pulse depends on wire materials (Al, Cu, W) used in the load and the exploding wire arrays. We will also present experimental results towards formation of shell-like loads by merging of plasmas of expanded pre-conditioned wires. Investigations of the implosion dynamics of single wires, uniformly pre-expanded to ~3mm diameter before application of the fast rising MA level current, will be also presented.