Implosion Dynamics and Spectroscopy of Nested and Small Radius Single Cylindrical Arrays on the 1 MA Cobra Generator at Cornell

Abstract

Summary form only given. Experiments with low-wire-number nested arrays from Al, stainless steel and brass wires have been performed on the 1 MA COBRA generator at Cornell University. Diagnostics included fast X-ray and EUV detectors, time-integrated X-ray pinhole cameras, a time-gated EUV/X-ray imaging pinhole camera, time-gated and time-integrated X-ray spectrometers, an optical streak camera and laser imaging. Nested arrays consisted of 16 wires with eight wires in outer (13 mm diam.) and inner (6 mm diam.) arrays. Uniform arrays used the same material, while combined arrays used different materials in inner and outer arrays. In addition, single uniform small diameter (6 mm) cylindrical arrays from the same materials and with the same number of wires were studied. The shapes of X-ray and EUV signals as well as the structures of X-ray and EUV pinhole images were analyzed as a function of the specific type of wire-array load. Time-gated pinhole cameras and a gated X-ray spectrometer were set up to record the beginning of the X-ray bursts. This allows the study of the beginning of the stagnation phase and a comparison to the time-gated spectra and images recorded after the main X-ray burst. Non-LTE kinetic modeling of K-shell (Al and Mg) and L-shell (Cu and Zn) of X-ray spectra provided the spatial (time integrated) and time-resolved (spatially integrated) plasma parameters. The importance of using time-gated spectroscopy for the study of nested wire arrays is discussed.