Meso-Scale Metrology Tools: A Survey of Relevant Tools and a Discussion of Their Strengths and Weaknesses
Lawrence Livermore National Laboratory, LLNL, manufactures laser experiment targets made of cylindrical and spherical components and assemblies that are generally 2 mm in size or smaller, which are machined with micron level accuracy. The targets illustrated in Figure 1 exhibit many features that are common to typical inertial confinement fusion, ICF, and high energy density laser targets. The left side of Figure 1 illustrates a cylindrical target composed of multiple materials of various shapes, including a disk that has a multi-mode sinusoid with a 4 {micro}m amplitude cut into it. The spherical target on the right consists of an inner capsule surrounded by four concentric hemispheres made of foams and polystyrene that are bonded together at a butt joint. Targets such as these are currently being manufactured for laser experiments conducted on the Omega Laser at the University of Rochester, and they are beginning to be fabricated for the National Ignition Facility (NIF). The targets need to be fully characterized with an uncertainty of {+-} 1 {micro}m, but in approximately five years, the required accuracy is expected to become {+-} 0.25 {micro}m. It is difficult to find metrology tools than can adequately measure these laser targets. The requirements for a laser experiment revolve around matching experimental laser shot results with results from predictive physics codes. The ability to provide a complete set of accurate dimensional metrology on a target is the input to the physics model. Therefore any inaccuracy or lack of data, affects the accuracy of the predictive model. In fact, it is more critical to have accurate metrology data rather than accurate manufacturing in this case. Diagnostics of the experimental results and the ability to resolve the physical behavior of the effect being modeled is the other element of the experiment cycle that is critical. Any of these errors reduces the ability to match the experimental and theoretical findings. One of the tasks of LLNL's target fabrication group is to address metrology capabilities at the meso-scale, several of which are described in the current paper.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15003278
- Report Number(s):
- UCRL-JC-151048; TRN: US0402530
- Resource Relation:
- Conference: ASPE Topical Meeting, Gainesville, FL (US), 01/21/2003--01/23/2003; Other Information: PBD: 1 Dec 2002
- Country of Publication:
- United States
- Language:
- English
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