Target Area Design Basis and System Performance for the National Ignition Facility
Target Area Design Basis and System Performance for the National Ignition Facility

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Published: 1994

Total Pages: 10

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A description of Target Area systems performance shows that the target area conceptual design can meet its performance criteria. Before the shot, the target area provides a vacuum of 5 × 10−5 Torr within 2 hours. A target, cryogenic or non-cryogenic, is placed to within 1 cm of chamber center with a positioner that minimizes vibration of the target. The target is then aligned to d"7 [mu]m by using the Target Alignment Sensor (TAS) system. The viewers in this system will also determine if the target is ready for illumination. Diagnostics are aligned to the necessary specifications by the alignment viewers. The target is shot and data is collected. Nearly all tritium (if present) is passed through the vacuum system and into the collection system. The analysis that supports the target area design basis is a combination of careful assumptions, data, and calculations. Some uncertainty exists concerning certain aspects of the source terms for x-rays and debris, material responses to this energy flux, and the full consequences of the material responses that do occur. For this reason, we have selected what we believe are conservative values in these areas. Advanced conceptual design activities will improve our understanding of these phenomena and allow a more quantitative assessment of the degree of conservatism inherent to the system. However, the results of this preliminary survey of target area operations indicate an annual shot rate of 600 (for the mix of shots shown in Table 1) is feasible for this set of target area systems.

Target Area Structural Support Systems Design to Achieve the Micron-level Stability Requirement of the National Ignition Facility (NIF).
Target Area Structural Support Systems Design to Achieve the Micron-level Stability Requirement of the National Ignition Facility (NIF).

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Published: 1994

Total Pages: 5

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The Target Area Structural Support (TASS) systems are designed to provide an optically stable support for the target area systems and personnel access platforms for the 192 laser beam configuration. The conceptual design of the TASS systems was an optimum configuration selected from three designs on which performance studies were conducted. The supporting bases for the design selection were the analytical results, operation, and cost effective.

Target Area Chamber System Design for the National Ignition Facility
Target Area Chamber System Design for the National Ignition Facility

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Published: 1994

Total Pages: 6

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The National Ignition Facility (NIF) is a proposed Department of Energy facility which will contribute to the resolution of important Defense Program and inertial fusion energy issues for energy production in the future. The NIF will consist of a laser system with 192 independent beamlets transported to a target chamber. The target chamber is a multi-purpose structure that provides the interface between the target and the laser optics. The chamber must be capable of achieving moderate vacuum levels in reasonable times; it must remain dimensionally stable within micron tolerances, provide support for the optics, diagnostics, and target positioner; it must minimize the debris from the x-ray and laser light environments; and it must be capable of supporting external neutron shielding. The chamber must also be fabricated from a low activation material. The fusion reaction in the target gives off neutrons, x-ray and gamma rays. The x-rays and gamma rays interact with the interior of the target chamber wall while neutrons penetrate the wall. In order to minimize the neutron activation of components outside the target chamber and to absorb gammas emitted from the activated chamber, shielding will be placed immediately outside the chamber. The target chamber contains the target positioner. The target positioner moves the target from outside the chamber to the center of the chamber and positions the target at the focal spot of the laser beams. The target positioner must be survivable in a harsh radioactive environment. The materials used must be low activation and have a high stiffness to weight ratio to maintain target stability. This paper describes the conceptual design of the target chamber, target postioner, and shielding for the NIF.