High-velocity Krypton Z-pinch Implosions On Saturn

The authors have explored the high velocity implosion limit of krypton gas-puff z-pinch implosions in an effort to efficiently generate K-shell radiation from high-Z elements. Using Saturn, a fast electrical generator, they imploded krypton gas-puff z pinches attaining implosion velocities as high as 125 cm/{mu}s. They observed the magneto Raleigh-Taylor instability in the fastest implosions. Despite the high implosion velocities, the plasma was never observed to attain the He-like ionization state, most likely because of inadequate density giving too long an ionization time. The dominant ionization state at peak compression was Ne-like Kr. They measured radiation yields as high as 100 J from Kr K{sub {alpha}} transitions. They used two different nozzle configurations for these experiments: 2.5-cm mean diameter nozzles and 3.5-cm mean diameter nozzles. Both sets of nozzles had exits with a 1-cm width. These nozzles are designed to have a 5-degree inward tilt to reduce the effect of zippering. The gas valve timing was adjusted relative to the generator so that the implosion occurred during the time when the gas density was increased. This also acted to reduce the effect of zippering. VUV preionization of the Kr was used for all of these shots. The pinch length wasmore » 2 cm. Current in the z pinch was measured with both B-dot current monitors and piezoelectric pressure transducers.« less