Veronica M. Gomez

Coating techniques used in target fabrication

Abstract A review of coating techniques used to fabricate targets and experimental components is presented. Coating techniques include physical vapor deposition, chemical vapor deposition, electroplating and dip coating. In all cases the substrate or mandrel material is removed from the coating to result in the final part.

BEST PRACTICE PROCEDURES FOR MAKING DIRECT DRIVE CYLINDRICAL TARGETS FOR STUDIES OF CONVERGENT HYDRODYNAMICS

Abstract The production of cylindrical targets involves numerous steps. These steps are shared in common with many other types of Inertial Confinement Fusion (ICF) targets but no other single target encompasses such a wide range of fabrication techniques. These targets consist of a large number of individual parts, virtually all fabricated from commercially purchased raw material. As an example, the polystyrene used is synthesized in house from purchased monomer material. This material must be polymerized, purified, characterized and put into solution before it is even first used in the making of a target. Because virtually every manufacturing and assembly process we currently use is involved in the production of these targets, this paper is written as a way documenting the methods used.

Targets for laser-driven opacity measurements

Abstract Special laser targets have been designed and fabricated which allow the opacity of materials to be experimentally determined at elevated temperatures ( kT ≤ 200 eV). A general description of the technique is presented, as well as the fabrication steps necessary to produce the targets. A uniform high temperature environment is provided by the use of small millimeter-sized hohlraums driven by the Nova laser at Lawrence Livermore National Laboratory. The material sample is placed within the hohlraum and is further illuminated by the X-rays produced by one or two of the Nova beams incident on a second material known as a back lighter. Thus far, silver and niobium opacity samples have been used, and each has required a different fabrication technique.

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.

Fabrication of the 3.2 gram Pegasus-II aluminum liner and load components of the Liner Ejecta Experiment

Fabrication of the 3.2 gram Pegasus-II 1100 series aluminum liner is described. This liner is driven by nominally 5 MA from the Pegasus-II two-stage Marx bank charged to approximately 35 kV. The liner will accelerate symmetrically to a final velocity of 3 mm//spl mu/s while it remains in contact with an annular glide plane surface at each electrode for a radial distance of 7.5 mm. At this drive level, up to 300 kbar shocks are expected when the solid density liner wall collides with the surface of a cylindrical liner experiment assembly mounted on axis within the liner bore. Components of the Los Alamos Liner Ejecta Experiment are described as one example of a Pegasus-II liner experiment.

Loads for pulsed power cylindrical implosion experiments

Pulse power can be used to generate high energy density conditions in convergent hollow cylindrical geometry through the use of appropriate electrode configuration and cylindrical loads. Cylindrically symmetric experiments are conducted with the Pegasus-II inductive store, capacitor energized pulse power facility at Los Alamos using both precision machined cylindrical liner loads and low mass vapor deposited cylindrical foil loads. The liner experiments investigate solid density hydrodynamic topics. Foil loads vaporize from Joule heating to generate an imploding cylindrical plasma which can be used to simulate some fluxes associated with fusion energy processes. Similar experiments are conducted with {open_quotes}Procyon{close_quotes} inductive store pulse power assemblies energized by explosively driven magnetic flux compression.