Experimental and Numerical Studies of Plasma Production in the Initial Stage of Implosion of a Cylindrical Wire Array

The features are studied of plasma production in the initial stage of implosion of hollow cylindrical wire arrays at electric-field growth rates of 1012 V/(cm s). The results are presented from the analysis of both UV emission from the wire plasma and the discharge parameters in the initial stage of the formation of a Z-pinch discharge. It is found that, a few nanoseconds after applying voltage to a tungsten wire array, a plasma shell arises on the wire surface and the array becomes a heterogeneous system consisting of metal wire cores and a plasma surrounding each wire (a plasma corona). As a result, the current switches from the wires to the plasma. A further heating and ionization of the wire material are due primarily to heat transfer from the plasma corona. A model describing the primary breakdown along the wires is created with allowance for the presence of low-Z impurities on the wire surface.