Study of Triple Ar Gas Puff Z-Pinches on 0.9-MA, 200-ns COBRA
Ar gas puff z-pinch experiments were conducted on the 0.9 MA, 200 ns COBRA generator at Cornell University. In the experiments, a triple-nozzle gas valve was used to produce the zpinch load with concentric outer and inner gas puffs and a central gas jet. We used Planer Laser Induced Fluorescence (PLIF) to measure the initial gas profile of the load, two 4-frame 4-ns gated XUV cameras to image the imploding plasma, and filtered Photo- Conducting Diamond Detectors (PCDs) to measure the x-ray output. We have observed shock heating and/or photoionization of the dense center jet by the imploding plasma. With an outer to inner plenum pressure ratio of 1:3, de-acceleration of the imploding plasma occurred when the outer plasma shell imploded on the inner shell resulting in a stable implosion. By varying the plenum pressure for the center jet, the x-ray emission was optimized. In conclusion, an Ar K-shell x-ray (3-4 keV) yield of 77±17 J was produced at a current level of 0.87±0.2 MA and an implosion time of 200-ns.