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Recent Developments in Fabrication of Direct Drive Cylinder Targets for Hydrodynamics Experiments at the OMEGA Laser

Abstract Experimental campaigns are being conducted at the 60 beam OMEGA laser at the University of Rochester’s Laboratory for Laser Energetics to acquire data to validate hydrodynamic models in the high energy-density regime. This paper describes targets that have been developed and constructed for these experimental campaigns. Targets are 860 μm inner diameter by 2.2 mm length cylinders with 70 μm thick polymer ablator. On the ablator inner surface and located halfway along the axis of the cylinder is a 500 μm wide Al marker band. Band thicknesses in the range 8-16 microns are used. CH foam with densities in the range 30-90 mg/cc fills the inside of the cylinder. While these targets have been fabricated for years, several new improvements and features have recently been developed. Improvements include the use of epoxy instead of polystyrene for the ablator, and the use of electrodeposited Al for the marker band. A critical feature of the target is the surface feature that is placed on the marker band. Experiments are aimed at understanding the hydrodynamic behavior of imploding cylinders as a function of this surface feature. Recent development work has focused on production of engineered surface features on the target marker band. Using a fast tool servo on a diamond turning lathe, a wide range of specified surface features have been produced. This paper will address improvements to the cylinder targets as well as current development efforts.