OBSERVATION OF A STABLE DENSE CORE WITHIN AN UNSTABLE CORONAL PLASMA IN WIRE-INITIATED DENSE Z-PINCH EXPERIMENTS

Dense Z-pinch plasmas initiated from a single 25-100 mum diam aluminum wire using a 100-350 kA, 100 ns current pulse have been studied with less-than-or-equal-to 1 ns time resolution. Rapid unstable expansion of a coronal plasma formed around the wire was observed with a subnanosecond pulsed nitrogen laser, while a dense core, which expanded more slowly and stably, was observed with 1-2 ns x-ray backlighting pulses. The core contained most of the initial wire mass, but there appeared to be little or no current flowing in it.