Effect of the prepulse current with an adjustable time-delay on the implosion dynamics of two-wire Z-pinch

Experiments are performed on the 'Qin-1' double pulse current generator at Xi'an Jiaotong University to study the effect of the prepulse current on the implosion dynamics of two-wire Z-pinches. An independent prepulse current with an adjustable time-delay (Tdelay) is introduced to preheat the wires before the start of the main pulse current. An estimation of the deposited energy and the areal density reconstructed from the interferogram suggest that the wires are partly vaporized with a gasification fraction of ∼67%. The prepulse preconditioning has a redistribution effect on the load mass, which determines the subsequent implosion process. The planar implosion of the two-wire load with a preset Tdelay ⩽ 450 ns can be divided into the two-layer phase and the merged implosion phase. The snowplow-like implosion is the main characteristic of the shot with a 1050 ns Tdelay. The ablation streams gradually disappear with the increasing Tdelay. The proportion of the mass that participates in implosion is increased as the preset Tdelay increases from 120 ns to 1050 ns.