Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90 deg. off-axis parabolic mirrors
- National Security Technologies, P.O. Box 809, Los Alamos, New Mexico 87544 (United States)
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)
Gas Cherenkov detectors (GCDs) have been used to convert fusion gamma into photons to achieve gamma bang time and reaction history measurements. The GCDs designed for OMEGA used Cassegrain reflector optics in order to fit inside a 10 in. manipulator. A novel design for the National Ignition Facility using 90 deg. off-axis parabolic mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO{sub 2} gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100 mm diameter by 500 mm long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO{sub 2} gas volume. A cluster of four channels will allow for increased dynamic range as well as for different gamma energy threshold sensitivities.
- OSTI ID:
- 21266521
- Journal Information:
- Review of Scientific Instruments, Vol. 79, Issue 10; Other Information: DOI: 10.1063/1.2969281; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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