The National Ignition Facility Neutron Imaging System

Journal Article · Wed Oct 15 04:00:00 EDT 2008 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.2987984· OSTI ID:21266518

Wilke, Mark D; Batha, Steven H; Bradley, Paul A; Day, Robert D; Clark, David D; Fatherley, Valerie E; Finch, Joshua P; Gallegos, Robert A; Garcia, Felix P; Grim, Gary P; Jaramillo, Steven A; Montoya, Andrew J; Morgan, George L; Oertel, John A; Ortiz, Thomas A; Payton, Jeremy R; Pazuchanics, Peter; Schmidt, Derek W; Valdez, Adelaida C; Wilde, Carl H ^[1]

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1. Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)

The National Ignition Facility (NIF) is scheduled to begin deuterium-tritium (DT) shots possibly in the next several years. One of the important diagnostics in understanding capsule behavior and to guide changes in Hohlraum illumination, capsule design, and geometry will be neutron imaging of both the primary 14 MeV neutrons and the lower-energy downscattered neutrons in the 6-13 MeV range. The neutron imaging system (NIS) described here, which we are currently building for use on NIF, uses a precisely aligned set of apertures near the target to form the neutron images on a segmented scintillator. The images are recorded on a gated, intensified charge coupled device. Although the aperture set may be as close as 20 cm to the target, the imaging camera system will be located at a distance of 28 m from the target. At 28 m the camera system is outside the NIF building. Because of the distance and shielding, the imager will be able to obtain images with little background noise. The imager will be capable of imaging downscattered neutrons from failed capsules with yields Y{sub n}>10{sup 14} neutrons. The shielding will also permit the NIS to function at neutron yields >10{sup 18}, which is in contrast to most other diagnostics that may not work at high neutron yields. The following describes the current NIF NIS design and compares the predicted performance with the NIF specifications that must be satisfied to generate images that can be interpreted to understand results of a particular shot. The current design, including the aperture, scintillator, camera system, and reconstruction methods, is briefly described. System modeling of the existing Omega NIS and comparison with the Omega data that guided the NIF design based on our Omega results is described. We will show NIS model calculations of the expected NIF images based on component evaluations at Omega. We will also compare the calculated NIF input images with those unfolded from the NIS images generated from our NIS numerical modeling code.

• OSTI ID: 21266518
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 79; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
APERTURES
BACKGROUND NOISE
CAPSULES
CHARGE-COUPLED DEVICES
COMPARATIVE EVALUATIONS
DESIGN
IMAGES
MEV RANGE
NEUTRONS
NICKEL SULFIDES
PLASMA DIAGNOSTICS
TRITIUM
US NATIONAL IGNITION FACILITY