Mass Density Profile Evolution from Wires in X-Pinch and Wire Array Configurations

Summary form only given. Understanding the ablation phase of wire arrays is a crucial part of their continued development in the drive towards inertial confinement fusion (ICF). In particular, accurate recovery of the ablated mass density profile evolution from experiments will provide invaluable data for comparison and validation of MHD codes, which in turn provides greater confidence in the scaling to higher current drivers. Two drivers (80 kA, 40ns risetime and 250 kA, 150ns risetime) have been used at UCSD to drive fine wires in several different configurations. These include x-pinches, wire-´pusher´ experiments and various wire array designs. The ablation rate of the wire cores can be inferred from measurements of the density profile at several times, and give information regarding the scaling of the ablation rate with current as well as the ratio of local and global magnetic fields in comparable set-ups. In addition, the results obtained from the above study can be compared to those from cylindrical wire arrays at IMA on the MAGPIF generator at Imperial College. Quantitative measurement of precursor plasma structures can again infer the ablation rate history of the array for comparison to modeling and lower current scalings. Diagnostics used in these experiments include XUV framing cameras, XUV spectroscopy, 2-frame interferometry, and 2 frame, quantitative x-pinch radiography. Results comparing the experimentally observed density profiles will be presented along with comparisons to MHD simulations and analytical models.