Development of a Flying Coil Valve and Precision Nozzle Throats to Achieve Uniform and Repeatable Cylindrical Gas Puffs for Z-Pinches

Summary form only given. Z pinches are a well established method to produce pulsed X-rays (plasma radiating sources, PRS). Depending on the application, different spectral contents are desired which means that a range of atomic numbers should be available for use in the Z-pinch load. Gas puff loads complement the capabilities provided by wire array loads, offering the use of gases such as neon, argon and krypton. For consistent X-ray output, it is important that the gas puff provide a consistent amount and spatial distribution of the gas. We report here on the development of a new method for producing a repeatable, uniform, cylindrical flow in a double-shell supersonic gas nozzle. By careful shaping of the nozzle profile, as well as precise control of the total mass output, we have been able to achieve good shot-to-shot repeatability in PRS performance. Typically, most gas nozzles have used a poppet-type valve configuration and precision, high cost nozzle components. We will describe a significantly different approach using 1) a fast "flying coil" valve and 2) precise but inexpensive valve throats using disposable, stainless steel laser-cut sheets. These changes enable high puff to puff repeatability of both total mass output as well as the mass spatial distribution with inexpensive, easily machined, disposable aluminum nozzle components. We discuss the design of the flying coil valves and the throat plate concept, review the quality-control techniques, and give examples of the observed gas flows plus data on implosion time and K yield reproducibility