Persistence of a neutral core in a wire load Z-pinch

Summary form only given. Various diagnostics have been fielded on a single wire Z-pinch that strongly indicate that much of the aluminum wire persists as a central core consisting of neutral vapors and liquid particles. Using the optical techniques of interferometry and shadowgraphy the evolution of the wire core was studied for a long pulse mode (250 kA, 1.5 /spl mu/s rise) and a short pulse mode (100 kA, 100 ns rise). Streaked shadowgrams give evidence of a highly absorbing central core which grows to a diameter of /spl sim/1 mm in the first 300 ns of the long pulse. For both the long and short pulses, aluminum particles can account for up to thirty percent of the original load mass. The results indicate that significant portions of the load are not vaporized and ionized and do not participate in the plasma dynamics of the pinch.