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

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
783382
Report Number(s):
LA-UR-01-3893
TRN: AH200134%%296
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Jul 2001
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HYDRODYNAMICS; TARGETS; LANL

Citation Formats

N. ELLIOTT, C. W. BARNES, and ET AL. BEST PRACTICE PROCEDURES FOR MAKING DIRECT DRIVE CYLINDRICAL TARGETS FOR STUDIES OF CONVERGENT HYDRODYNAMICS. United States: N. p., 2001. Web.
N. ELLIOTT, C. W. BARNES, & ET AL. BEST PRACTICE PROCEDURES FOR MAKING DIRECT DRIVE CYLINDRICAL TARGETS FOR STUDIES OF CONVERGENT HYDRODYNAMICS. United States.
N. ELLIOTT, C. W. BARNES, and ET AL. Sun . "BEST PRACTICE PROCEDURES FOR MAKING DIRECT DRIVE CYLINDRICAL TARGETS FOR STUDIES OF CONVERGENT HYDRODYNAMICS". United States. doi:. https://www.osti.gov/servlets/purl/783382.
@article{osti_783382,
title = {BEST PRACTICE PROCEDURES FOR MAKING DIRECT DRIVE CYLINDRICAL TARGETS FOR STUDIES OF CONVERGENT HYDRODYNAMICS},
author = {N. ELLIOTT and C. W. BARNES and ET AL},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jul 01 00:00:00 EDT 2001},
month = {Sun Jul 01 00:00:00 EDT 2001}
}

Conference:
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  • We have made targets with cylindrical geometry for Inertial Confinement Fusion (ICF) experiments. These targets are used in hydrodynamic experiments on the OMEGA laser at the University of Rochester. The cylindrical design allows the study of three dimensional hydrodynamic effects in a pseudo 2D mode, simplifying data gathering and analysis. Direct drive refers to the fact that the target is illuminated directly by approximately 50 laser beams and is imploded by the material pressure generated from ablation of the outside of the target. The production of cylindrical targets involves numerous steps. These steps are shared in common with many othermore » types of ICF targets but no other single target type encompasses such a wide range of fabrication techniques. These targets consist of a large number of individual parts, all fabricated from commercially purchased raw material, requiring many machining, assembly, electroplating and chemical process steps. Virtually every manufacturing and assembly process we currently possess is involved in the production of these targets. The generic target consists of a plastic cylinder (ablator) that is roughly lmm in diameter by 2.25mm long. The wall of the cylinder is roughly 0.07mm thick. There is an aluminum cylinder 0.5mm wide and O.Olmm thick centered on the inside of the plastic cylinder and coaxial with the outside plastic cylinder. The outside of this aluminum band has surface finishes of differing random average roughness. The required average surface roughness is determined in advance by experimental design based on the amount of turbulent mix to be observed. The interior of the cylinder is filled with low density polystyrene foam that is made in house. To produce a finished target additional features are added to each target. X-ray backlighters are cantilevered off the target that allow time resolved x-ray images of the imploding target to be recorded during the experiment. The x-ray backlighters are driven by additional laser beams that are delayed to record an image at the appropriate time after the main beams are fired. An aperture to limit the area imaged and reduce x-ray background is placed on the target opposite the backlighters. Finally, alignment fibers that allow the target to be located precisely in three dimensional space before being shot are placed in several locations on the outside of the target.« less
  • Experiments have been performed on the OMEGA Laser Facility to study the hydrodynamics of directly driven cone-in-shell, fast-ignitor targets. A 35 degree or 70 degree opening-angle gold cone was inserted into spherical plastic shells of ~24-um thickness and ~870-um diameter, which were imploded with up to 21 kJ of 351-nm laser light. A backlighter was used on some experiments to compare the fuel assembly of targets with or without a high-pressure fill gas. The shock breakthrough to the inside of the cone, where the ultrafast laser propagates in integrated fast-ignitor experiments, was studied using a streaked optical pyrometer. No plasmamore » was seen inside the cone before the assembled core reached peak compression.« less
  • The characterization of OMEGA cryogenic targets is based on shadowgraphs obtained from multiple angular views taken with the target in the layering sphere. The D2 ice has been observed to re-layer during slow rotations, leading to procedural changes that avoid re-layering thus ensuring high-quality, spherical-harmonic, 3-D ice layer reconstructions.
  • 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 {mu}m inner diameter by 2.2 mm length cylinders with 70 {mu}m thick polymer ablator. On the ablator inner surface and located halfway along the axis of the cylinder is a 500 {mu}m wide Al marker band. Band thicknesses in the range 8-16 microns are used. CH foam with densities in themore » 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.« less
  • Recent advances in hydrodynamics theory and experiments at the Laboratory for Laser Energetics are described. Particular emphasis is laid on improvements in the implosion stability achieved by shaping the ablator adiabat and on the newly developed designs for fast ignition fuel assembly. The results of two-dimensional simulations and a recent set of implosion experiments on OMEGA are presented to verify the role of adiabat shaping on the hydrodynamic stability of direct-drive implosions.