Gas puff implosion measurements and modeling

Two-dimensional interferometric images obtained in gas-puff z-pinch experiments on the Hawk generator are compared with snowplow calculations using the measured gas distribution for various times during the 250-ns implosion. To match the calculated implosion time with the observed implosion time, 88% to 101% of the measured cathode current, adjusted for each shot, is required to implode the snowplow. The snowplow model reproduces the (r,z) shape of the measured 2-D plasma shell at different times during the implosion. The inferred current loss between the measurement location (17-cm upstream of the nozzle) and the z-pinch may be due to vacuum flow resulting from the plasma-opening switch.