Studies of maltiwire X pinches from 0.4 to 1 MA

Summary form only given. The plasma formation and implosion characteristics, as well as the energy in X-ray radiation, from two and multiwire X pinches have been investigated and compared using the XP and COBRA pulsed power generators at Cornell University. The XP generator (40-50 ns rise time, 450 kA peak current) has been used for the X pinch studies and applications for several years. The rebuilt COBRA generator, which has a variable current pulse waveform and amplitude (95-150 ns rise time, 0.9-1 MA peak current), has extended the range of current pulse parameters available at Cornell for X pinch studies. X pinches with 2 to 12 wires, with diameters from 10 to 75 mum, and made of several different wire materials (from Al to W) have been tested. The influence of the rate of rise of current and the X pinch wire mass on X pinch plasma formation, radiated energy and pinch implosion dynamics has been investigated using a broad range of diagnostics with spatial and/or temporal resolution. Two or multiwire X pinches were placed in the diode center and/or one or two X pinches were placed in one or two of the four parallel return current posts of the diode. Radiographic images of different test objects, wires in wire-array Z-pinches and the X pinches, themselves, were obtained with mum scale spatial resolution. Differences between 2 and multiwire X pinch implosion dynamics and X-ray energy yield were studied in the experiments. The substantially higher energy yield and harder radiation spectrum from multiwire X pinches than from two wire X pinches enables imaging of thicker (more absorbing) objects without increasing the load current. The multiwire X pinches also have more predictable behavior that is almost independent of the wire material