Uniform-fill nozzles for long-implosion-time PRS experiments

Summary form only given, as follows. We have continued our development and testing of uniform-fill nozzles for long-implosion time PRS sources on the 4 MA Double-EAGLE generator at Maxwell Physics International. By adjustment of switch gaps in the waterline, the nominal 100 ns electrical pulse of Double-EAGLE can be extended to 200 or 250 ns with little decrease in peak current. We have used these modes to test 7 and 10 cm diameter uniform fill gas puffs in well diagnosed experiments. The 7 cm nozzle generated a K-shell yield in excess of 15 kJ in a 16 ns FWHM pulse at 188 ns implosion time and demonstrated I/sup 4/ scaling to the testing limit of 4 MA. The final implosion diameter was about 2 mm. The compression ratio was therefore better than that achieved in short pulse operation (2.5 cm initial shell diameter to 1 mm final pinch diameter). We will discuss these Z-pinch results, the 10 cm nozzle results, and features of the gas valve and nozzles employed to produce them.